Abstract Submitted to Thin Films 2010

Abstract

[This data base has been modified on 19 November 2014 There are 128 submissions ].

NNF 2036, Poster, Effect of grain size on magnetic properties and microstructure of Ni80Fe20 thin films

Chen Yuan-Tsung;Lin Y.C.
Department of Materials Science and Engineering, I-Shou University, Kaohsiung Taiwan 840, R.O.C.; Taiwan

An experiment is performed in which an Ni80Fe20 target is used to deposit a monolayer Ni80Fe20 thin film on a glass substrate by dc magnetron sputtering. The layer has a thickness (tf) from 300 Å to 1000 Å and is formed under the following conditions; (a) the substrate temperature (Ts) is maintained at room temperature (RT) and (b) annealing is carried out at TA = 250℃ for 1 h. To determine the distribution of the grain sizes, the plane-view microstructure of each NiFe thin film was observed under a high-resolution transmission electron microscope (HRTEM). The electron diffraction pattern (SAD) reveals that the NiFe thin film had a face-centered cubic (FCC) NiFe structure at RT and the aforementioned annealing conditions. It also indicates that the crystallization of the post-annealed NiFe film is stronger than that of the film deposited at RT without annealing. The coercivity (Hc) and magnetic squareness (SQR, Mr/Ms) ratio of the in-plane magnetic hysteresis loop were measured using a superconducting quantum interference device (SQUID), where Mr denotes the remanence magnetization and Ms represents the saturation magnetization. The distribution of grain sizes is related to the coercivity. The magnetic remanence properties and squareness ratio of the NiFe thin films also depend on grain size. The SQR value of the NiFe thin film increases upon annealing because the ordered spins in the NiFe thin film are randomized by the thermal vibration. Accordingly, Mr is increased and Ms is reduced. Hence, the SQR value decreases as the thickness of thin film increases because the refinement of the grains reduces the effective anisotropy, strengthening the ferromagnetic exchange coupling interaction. Keywords: Grain size effect; NiFe thin films; Post-annealing effect PACS No: 64.70.Pf; 75.70.Kj; 81.05.Kf a)Corresponding author: Yuan-Tsung Chen TEL: +886-765-777-11Ext. 3119, FAX: +886-765-784-44 E-mail: ytchen@isu.edu.tw

NNF 2052, Invited Lecture, Modelling and predicting the properties of diamond-liek carbon nanocomposites [Invited]

Chua Daniel;
Dept of Materials Science & Engineering, NUS; Singapore

Diamond-like carbon (DLC) has been the subject of many research efforts over the last three decades. Due to the presence of high sp3 content, DLC exhibits properties that closely resemble those of diamond, such as high mechanical hardness, wear resistance, highly resistive, chemically inert and low coefficient of friction. The material properties of DLC can be further modified by simply incorporating single system (or element) dopants. However, the method used for choosing the type of dopant incorporated is trial-and-error. First, despite extensive studies on various growth and kinetic modeling, limited study has been devoted to the energy dependency in surface evolution and changes of microstructure of DLC nanocomposite. As such, using TRIM and analytical modeling, we showed that the change in the energy absorbed by the composite targets has an effect on the resultant surface, microstructural and mechanical properties. We further expand this model to predict the properties of DLC nanocomposites with metals dopants such as Ni, Mn and Ti. To validate our modeling results, corresponding films have been deposited using PLD technique and characterized. We concluded that the material properties of the DLC nanocomposites can be accurately predicted simply based on the first ionization potential and coefficient of extinction of the metal. Second, we further expanded the DLC nanocomposites by incorporating compounds into DLC to engineer its material properties. For example, when ZnO is incorporated into DLC, for the first time, monochromatic ultraviolet photoluminescence at 377 nm was observed from a DLC nanocomposite. We further show that these effects can be observed in DLC nanocomposites deposited using FCVA and PLD. Other compounds include Ti-Ni and AlN will also be presented.

NNF 2053, Oral, Multilayer DLC Coatings via Cycling the Substrate Bias Voltage during FCVA Deposition

Li Feng Ji1;Zhang Sam1; Sun Deen2; Li Bo3
1School of Mechanical and Aerospace Engineering, Nanyang Technological University; Singapore
2PVD Department Plating Division, Singapore Epson Industrial Pte Ltd;Singapore
3Central Iron and Steel Research institute;China

To combat the residual stress and the brittleness in single-layer diamond-like carbon (DLC) coatings, multilayer DLC coatings constructed with alternating sp3-rich and sp2-rich carbon layers of identical sublayer deposition duration have been fabricated on magnetron sputtered titanium “bonding” interlayer via cycling the substrate bias voltage during filtered cathodic vacuum arc deposition. The role of the substrate bias voltage and the carbon sublayer deposition duration on the surface roughness, cross-sectional morphology, residual stress, hardness and adhesion of the monolayer and multilayer coatings has been examined. The stress neutralization effect of the Ti interlayer, the back-sputtering resultant dynamic annealing, and the interfacial carbon ion diffusion effect between the carbon sublayers are explored. It shows that bias-multilayered deposition gives rise to DLC coatings of high toughness, reduced residual stress, improved adhesion while maintaining moderate hardness.

NNF 2055, Oral, Microstructure and mechanical properties of W-Ni-N coatings prepared by magnetron sputtering

Yang Junfeng;Jiang Yan; Wang Xianping; Yuan Zhigang; Fang Qianfeng
Institute of Solid State Physics, Chinese Academy of Sciences; China

W-Ni-N coatings were fabricated by dc magnetron sputtering technique. The influence of Ni concentration on microstructure, surface morphology and mechanical properties of coatings was investigated schematically by using X-ray diffraction,Transmission electron microscope scanning electroic microscopy,nanoindenter, and Scratcher. Results exhibited that the addition of Ni into W-N films induced the change of grain morphology from plate to granular shape leading to the reduction in contact area between film and substrate. Therefore, the adhesion strength of W-Ni-N decreased from 60 to 38 N as Ni content increase from 0 to 21 at.%. In contrast, the hardness increased slightly at first and then decreased with Ni concentrations. The maximum hardness of 38 GPa was obtained at the nickel content of 10 at.%, corresponds to an composite structure of nc-W2N+nc-Ni-W alloy+Ni.

NNF 2057, Invited Lecture, Limits to the Preparation of Super- and Ultrahard Nanocomposites (invited)

Veprek Stan;
Department of Chemistry, Technical University Munich, Lichtenbergstr. 4 D-85747 Garching; Germany

There is a continuing discussion about the reliability of the very high hardness reported by us for the nc-TiN/a-Si3N4 and nc-TiN/a-Si3N4/TiSi2 nanocomposites. In my presentation I shall first show that the recent claims of Fischer-Cripps et al. [1], that our measurements of the very high hardness were incorrect, is based on their fitting of incorrect indentations curves. Original SEM micrographs confirm our reported highest hardness of 80–100 GPa. May talk will concentrate on the discussion the deposition conditions needed for achieving such high hardness, which is combined with high resistance of these materials against brittle fracture and with high oxidation resistance at elevated temperatures, to show the critical role of minor oxygen impurities which strongly degrade the mechanical properties [2]. The recent results have shown that the impurities also hinder the segregation of the TiN and Si3N4 phases and the formation of stable nanostructure, thus apparently stabilizing the Ti-Si-N solid solution. At a level of about 0.8 at.% of oxygen, the temperature needed for the "recrystallization" of the solid solution approaches 1000°C. Because the Si-O bond is the strongest one in the system and SiO is volatile at this temperature, silicon is lost from the films and the formation of the nanocomposites becomes impossible. Therefore, for any further progress in the basic materials science we need to reduce the oxygen impurities in the coatings below 100 ppm. FinallyI shall demonstrate examples of coatings with impurities (O, H, C) of 700-1000 ppm which have been deposited in large industrial coating unit, and discuss the possibilities of further improvement. [1] A.C. Fischer-Cripps et al., Philos. Mag. 2012 in press [2] S. Veprek, Invited Review, J. Nanosci. Nanotechnol.

NNF 2063, Poster, Magnetic reversal and decoupling mechanisms of Cu/FePt(001) films

Wei D. H.1;Tang H. H.1; Chung C. J.1; Ho Y. K.1; Chi P. W.1; Chao C. H.1; Yao Y. D.2
1Institute of Manufacturing Technology & Graduate Institute of Mechanical and Electrical Engineering, National Taipei University of Technology; Taiwan
2Institute of Applied Science and Engineering, Fu Jen University;Taiwan

Ordered Fe-based intermetallic phases are of the most potential candidates for application in magnetic recording media and permanent magnets. We aimed to control the magnetic interaction of the FePt(001) films by introducing the Cu capping nanolayers to increase interfacial energy. [Fe(1 nm)/Pt(1 nm)]10 multilayers were prepared by e-beam evaporation on MgO(100) substrates at different deposition temperatures ranged from 300 to 500 oC, and Cu nanolayers were capped atop FePt films and its thickness was varied from 0, 1, 2, 4, to 6 nm. Out-of-plane coercivity increases with increasing the growth temperature for all films. The reduction of grain/domain size and intergrain interaction of FePt can be achieved by such capping nanolayer and maintain (001) texture. For the relative low temperature of 300 oC, Cu could penetrate into the FePt nanostructures along the grain boundaries and create a strain-energy modulation at the interface due to its lower surface energy than that of pure Fe or Pt. The enhancement (50%) of the coercivity from 3000 Oe (without Cu) to 4500 Oe (4 nm Cu) is due to the reduced exchange coupling of FePt magnetic grains originated from inhomogeneous Cu atoms diffusion along grain boundaries confirmed from the secondary electron image (SEI) and backscattering electron image (BEI) images. Studies of angular dependent coercivity show a tendency of a domain-wall motion shift toward rotation of reverse-domain type with Cu capping nanolayer onto the FePt(001) films. The intergrain interaction was confirmed from the Kelly-Henkel plot that indicated the strong exchange coupling between neighboring grains in the FePt films without Cu addition. On the other hand, the negative δM value was obtained while the FePt films capped with Cu nanolayer, indicating the Cu (002) capping nanolayer can lead to the reduction of intergrain exchange coupling thus presence of dipole interaction in the Cu/FePt(001) films.

NNF 2066, Poster, Impact of Plasma treatment on Structure and Electrical Properties of Porous Low Dielectric Constant SiCOH Material

Cheng Yi-Lung1;Huang Jun-Fu1; Chang Yu-Min2; Leu Jiherng2; Chang Wei-Yuan1
1Department of Electrical Engineering, National Chi-Nan University,; Taiwan
2Department of Materials Science and Engineering, National Chiao-Tung University;Taiwan

Porous dielectric materials are needed for advanced technologies to improve signal propagation. The integration of porous low-k films faces more severe challenges due to the presence of porosity. Plasma treatments and ashing processes have been considered to be critical steps to impact the low-k films’ properties. In this study, the impact of various plasma treatments on the porous low-k dielectrics deposited by plasma enhanced chemical vapor deposition (PECVD) was investigated. All the plasma treatments resulted in the formation of a thin and dense layer on the surface of the porous low-k films. Additionally, the properties of the porous low-k dielectric were severely damaged by oxygen plasma treatment. However, H2/He plasma treated low-k dielectric by remote plasma method can help to protect the low-k film against oxygen plasma induced damage.

NNF 2068, Poster, Dynamic Annealing Effect during Filtered Cathodic Vacuum Arc Deposition of DLC Coatings

Li Feng Ji1;Zhang Sam1; Sun Deen2
1School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798; Singapore
2PVD Department Plating Division, Singapore Epson Industrial Pte Ltd, 86 & 88, Second Lok Yang Rd Jurong, 628162;Singapore

Demonstrated is the fast deposition of thick DLC coatings of high hardness and yet low residual stress via introducing a titanium (Ti) interlayer. The process makes use of both the unbalanced magnetron sputtering and filtered cathodic vacuum arc (FCVA) deposition. Unbalanced magnetron sputtering is used to deposit a thin Ti layer for bonding and FCVA deposition is used for its high deposition rate of thick and hard diamond-like carbon. The surface morphology, chemistry, bonding structure and mechanical properties of the coatings are examined for such coatings deposited at different substrate bias voltage during FCVA deposition. The results showed that the neutralization effect of the Ti interlayer, back-sputtering and dynamic annealing take place at too high substrate bias voltages.

NNF 2074, Poster, Life Prediction of Supercapacitor of Hydrous Ruthenium Oxide Mixed With Carbon Nanotube Additive during 100000 Times Charge-discharge Processes

Lin Yuli1;Huang Hou-Sheng12
1College of Engineering Science, Chung Hua University; Taiwan

In this study, the applicability of supercapacitor of the hydrous ruthenium oxide with or without carbon nanotube additive was examined. The cathodic deposition was used, which was fast and easy to prepare the electrode of supercapacitor. The electrical capacity characteristics were investigated by cyclic voltammetry. The specimen was measured at 1 V/s in the 0.5M H2SO4 through 105 times charge-discharge cycles. It was found that the specimen of hydrous ruthenium oxide without carbon nanotube oxide additive was acceptable during the 105 times charge-discharge processes. While the specimen of hydrous ruthenium oxide without carbon nanotube oxide additive was found not acceptable. The coating layer of hydrous ruthenium oxide on the carbon nanotube surface was found extremely thin, although carbon nanotube supplied huge coating area. The capacitance of the specimen without carbon nano tube additive was lower than the specimen with carbon nanotube additive, however the capacitance of specimen without carbon nanotube additive did not decay after 100000 times charge/discharge cycles.

NNF 2076, Oral, Role of Si and Layered Structure in Hard yet Tough Ceramic Coating

WANG YU XI1;ZHANG SAM1; LEE JYH-WEI2; LEW WEN SIANG3; SUN DEEN4; LI BO5
1School of Mechanical and Aerospace Engineering, Nanyang Technological University; Singapore
2Center for Thin Film Technologies and Applications, Mingchi University of Technology;Taiwan
3School of Physical and Mathematical Sciences, Nanyang Technological University;Singapore
5Central Central Iron and Steel Research institute;China

The effect of Si content on hardness and toughness in CrAlN ceramic coatings is studied in three increasing concentrations: 0.49 at%, 4.9 at% and 8.5 at%. As monolayer coatings, hardness of these coatings increases but toughness drops tremendously. Assembling of these three coating into one coating with increasing Si from the interface towards the top surface, the resultant coating of the same total thickness achieved five times increase of toughness (in terms of scratch adhesion toughness) without sacrifice of hardness as compared to the hardest monolayer nc-CrAlN/a-SiNx coating. Microstructures of each monolayer and the structured coating are examined in detail.

NNF 2097, Oral, Optically Isotropic, Colorless, and Flexible Polyimidothioethers/TiO2 Hybrids by Hydrothermal Treatment

Tsai Chia-Liang1;Yen Hung-Ju2; Liou Guey-Sheng3
1Institute of Polymer Science and Engineering, National Taiwan University; Taiwan
2Institute of Polymer Science and Engineering, National Taiwan University;Taiwan
3Institute of Polymer Science and Engineering, National Taiwan University;Taiwan

In this study, a new synthetic route was developed to prepare polyimidothioethers (PITEs)-nanocrystalline-titania hybrid optical films with a high titania content (up to 50 wt%) and thickness (15 ± 3µm) from soluble PITEs containing hydroxyl groups. A series of organosoluble PITEs were synthesized from the hydroxy-substituted dithiols with various commercial bismaleimides via Michael polyaddition. The hydroxyl groups on the backbone of the PITEs could provide the organic-inorganic bonding and resulted in homogeneous hybrid solutions by controlling the mole ratio of titanium butoxide/hydroxyl group. AFM, TEM, and XRD results indicated the formation of well-dispersed nanocrystalline-titania. The flexible hybrid films were successfully obtained and revealed good surface planarity, thermal dimensional stability, tunable refractive index, and high optical transparency. A three-layer anti-reflection coating based on the hybrid films was prepared and showed a reflectance less than 0.5% in the visible range indicated its potential optical applications.

NNF 2107, Oral, The microstructural and functional evolution of post-heated SnO2:F thin films

Gao Qian;Li Ming; Li Xiang; Han Gaorong
State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University; China

The influence of post-heat treatment on fluorine-doped tin oxide (SnO2:F) thin films deposited on glass substrate by atmospheric pressure chemical vapor deposition (APCVD) method on float production line was investigated. XRD, SEM and TEM measurements were employed to obtain the structure evolution during the process. It was found that the post-heated films showed polycrystalline nature and the morphology transformed from homogeneous micro-size grain structure to nano-size grain structure. The sheet resistance was found increasing sharply and suddenly under a relative long post-heating time~10min at 650°C (close to the temperature chosen for glass tempering in industry), with the decrease of low-emission properties. The relationship between microstructural evolution and low-e property was successfully uncovered, which provide the guidance for mass industry.

NNF 2112, Oral, Silica-coated silver nanoneedles array for SERS application

YANG Yong;LI Dan; HUANG Zhengren; LIU Guiling
Shanghai Institute of Ceramics, Chinese Academy of Sciences; China

Novel surface-enhanced Raman scattering (SERS) substrates with high SERS-activity are ideal for novel SERS sensors, detectors to detect illicitly sold narcotics and explosives. The key to the wider application of SERS technique is to develop plasmon resonant structure with novel geometries to enhance Raman signals and to control the periodic ordering of these structures over a large area to obtain reproducible Raman enhancement. Recently, we have developed a simple Ar+-ion sputtering route to fabricate silver nanoneedles arrays on silicon substrates for SERS-active substrates to detect trace-level illicitly sold narcotics. In this work, silica film are coatted on silver nanoneedles array in order to protect silver from oxidation and applied as SERS-active substrates.

NNF 2123, Oral, Formation and Characterization of Nanostructured Carbon from Silicon Carbide by Electrochemical Etching

Yoshimura M;Jaganathan Senthilnathan
Promotion Centre for Global Materials Research (PCGMR), Department of Material Science and Engineering, National Cheng Kung University, Taiwan; Taiwan

Carbide derived carbons (CDC) have received significant attention due to their unique properties. CDCs have been synthesized by using different precursors, including SiC, Al4C3, Fe3C, TiC, NbC and VC. Among these compounds, SiC is the most widely studied substrate for CDC growth because of its relatively low cost and high electrical, thermal, chemical stability and other properties. In CDC process, silicon atoms are selectively etched and the carbon structures can potentially be retained without changing the size and shape of the sample. CDCs can be formed from carbide precursors by many different methods, including acid or gaseous etching. However, chemical extraction of the metal atoms via halogenation, hydrothermal treatment and vacuum decomposition are the most common chemical reactions leading to carbon formation. Among these methods, halogenations and particularly chlorination has become one of the key synthetic methods for large-scale production of CDC. Major drawback in the synthesis of CDC by halogenation method is that high temperature is involved in this process, halogen gas is toxic making the process potentially hazardous. Preparation of CDC by soft solution process is an attractive alternative for the above mentioned problem. In the present study, preparation of CDC is endeavored by electrochemical etching of sintered SiC in hydrofluoric acid (HF) solutions in water, C2H5OH, CH3-CH2-CH2-OH, CH3CN and CH3-CO-CH3. Process parameters like the effect of reaction time and applied voltage can be easily controlled. Porous layer formed by etching in CH3CN+HF and C2H5OH+HF solutions is more uniform and homogeneous when compared to other solutions. The formation of carbon layers on the SiC surface was confirmed by Raman spectroscopy after the electrochemical etching with C2H5OH+HF solution. Raman spectra collected from different locations on the electrochemically etched sample showed G band at 1597cm-1 and weak D band at 1336cm-1. The structure and morphology of carbon on the surface of silicon carbide was characterized by TEM, SEM, Raman and EDX analysis.

NNF 2124, Oral, Rapid Micro-scale Patterning of alkanethiolate self-assembled monolayers by Micro-plasma Stamp

Weng Chih-Chiang1;Hsueh Jen-Chih2; Liao Jiunn-Der2; Yoshimura Masahiro1
1Promotion Center for Global Materials Research, Department of Materials Science and Engineering, National Cheng Kung University, No. 1,University Road, Tainan 70101, Taiwan; Taiwan
2Department of Materials Science and Engineering, National Cheng Kung University, No. 1,University Road, Tainan 70101, Taiwan;Taiwan

In recent years, materials with multiple surface properties in micro/nano scale are created by modern material engineering. Precise control of localized physical and chemical properties in designed patterns thus becomes a significant issue. In this study, Synchrotron-based scanning photoelectron microscopy was applied to study the quick micro-scale pattern transfer feasibility of self-assembled monolayers (SAMs) of Octadecanethiol (ODT) on Au (111) substrate by an active micro-plasma stamp. This active micro-plasma stamp using polydimethyl siloxane (PDMS) as a dielectric layer can generate the spatially defined plasma at atmospheric pressure using 100 KHz high voltage source based upon the principle of dielectric barrier discharge (DBD). The exact behavior depends on the SAM identity as well as on the character and composition of the plasma can be specifically adjusted to achieving the desirable effect on the exposed SAM layer. Therefore, the relationship between surface properties, e.g., chemical structure at surface, patterned dimension after physico-chemical reactions, and the operation parameters, e.g., applying voltage, the depth/width ratio of cavity on stamp, plasma igniting time, and the imprinted force between stamp and substrate will be discussed in this study. The expected result is that ODT SAMs can serve as either negative or positive monomolecular resists with adjusted plasma operation parameters and washing procedure after plasma treatment, as soon as the fabricated pattern is transferred to the underlying substrate.

NNF 2125, Oral, Thermal Conductivity of CrAlSiN Nanocomposite Coatings using Pulsed Photothermal Reflectance Technique

Kabiri Samani Majid1;Ding Xing-Zhao2; Khosravian Narjes3; Chen George4; Baillargeat Dominique3; Tay Beng Kang1
1School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue; Singapore
2Surface Technology Group, Singapore Institute of Manufacturing Technology, 71 Nanyang Drive;Singapore
3CINTRA-CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6,;Singapore
4BC Photonics Technological Company 5255 Woodwards Rd., Richmond, BC V7E 1G9;Canada

A series of CrAlSiN nanocomposite coatings with different (Al+Si)/Cr atomic ratio, with a thickness of around 3.0 µm were deposited on Fe-304 stainless steel substrates by a lateral rotating cathode arc process in a flowing nitrogen atmosphere. The composition and microstructure of the as-deposited coatings were analyzed by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). With the incorporation of Al and Si, both the CrAlN (111) and (200) peaks gradually shifted to higher diffraction angle, indicating a decrease of lattice parameters. Thermal conductivity of the as-deposited coating samples at room temperature was measured by using pulsed photothermal reflectance (PPR) technique [1-3]. With increasing the (Al+Si)/Cr atomic ratio, the coatings’ thermal conductivity decreased monotonously. This reduction of thermal conductivity could be ascribed to the variation of coatings’ microstructure, including the decrease of grain size and the resultant increase of grain boundaries, the disruption of columnar structure, and the reduced preferential orientation. [1] G. Chen, P. Hui, Thin Solid Films, 339 (1999) 58-67. [2] X.Z. Ding, M.K. Samani, G. Chen, Appl. Phys. A: Mater. Sci. Process., 101 (2010) 573-577. [3] J. Chen, T. Sun, D. Sim, H. Peng, H. Wang, S. Fan, H.H. Hng, J. Ma, F.Y.C. Boey, S. Li, M.K. Samani, G.C.K. Chen, X. Chen, T. Wu, Q. Yan, Chemistry of Materials, 22 (2010) 3086-3092.

NNF 2133, Oral, Sequentially dual-coated magnetic particles by silica and MWNT: Fabrication and physical characteristics

LIU Ying Dan;CHOI Hyoung Jin
Department of Polymer Science and Engineering, Inha University; Korea (south)

Soft magnetic carbonyl iron (CI) particles are the mostly favored and applied active particles as the dispersed phase in magnetorheological (MR) fluid which is a smart and intelligent suspension with the controllable phase transition from fluid-like to solid-like by an applied magnetic field. Rheological properties including shear stress, shear viscosity, and elastic/viscous modulus are the usually observed factors for a MR fluid to investigate its response to magnetic field. In the meantime, application studies of the MR fluid as mechanical interfaces such as damper systems are intensively carried out due to the large and controllable dynamic yield stress of the MR fluid. However, comparing to the continuous phase (e.g. silicone oil, mineral oil, or aqueous systems), the dispersed CI particles in which possess much higher density and are easy to settle when the MR fluid is left to stand without shacking. One useful and effective way to solve this problem is to encapsulate or coat the bare CI particles with materials in low densities. From this point of view, CI/polymer and CI/inorganics core-shell composite particles were prepared in previous study. In this work, we synthesized silica and multi-walled carbon nanotube (MWNT) dual-coated CI particles, the density of which was significantly reduced but without much loss in magnetic property. MR responses of the suspension basing on the synthesized particles in silicone oil were investigated by a rotational Physica rheometer using a parallel-plate cell and a MR device. In addition, the MR behaviors of this MR fluid were compared with that showed by the pure CI particles. Higher shear stress and elastic modulus were observed in the dual-coated particles due to the MWNT-arranged rough surface of the magnetic particles.

NNF 2135, Poster, Effect of the electrodeposition conditions on microstructure and magnetic properties of nanocrystalline CoFeNi thin films

Mehrizi Saeed;Heydarzadeh Sohi Mahmoud; Seyyed Ebrahimi Seyyed Ali
School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.B. Box: 14395-553, Tehran, Iran; Iran

In this investigation, nanocrystalline CoFeNi alloys thin films were electrodeposited from baths which were different from conventional CoFeNi baths. The utilized baths had natural pH (about 5) and contained sodium citrate as a complexing agent. The deposits were characterized by using SEM, EDS, XRD, TEM and VSM (vibrating sample magnometer) techniques. The relations between microstructure and magnetic properties of the deposited films were also studied. X-ray diffraction patterns indicated that average grain size, estimated by Scherrer formula, in all the deposited films were below 50 nm and films with mixes FCC+BCC phases and average grain size around 20 nm exhibited the smallest coercivity values. The results also showed that the coercivity of the deposited films followed D6 law but average grain size had no effect on the saturation magnetization of the deposited films. Films with very low coercivity (< 5 Oe) and high saturation magnetization (>1.8 T) were producible from the baths under specific conditions of current density and metal ion concentrations.

NNF 2137, Invited Lecture, Colloidal Monolayer at the Air/Water Interface: Large-Area Self-Assembly and In-Situ Annealing

YU Jie1;ZHENG Lu1; GENG Chong1; WANG Xiuyu1; YAN Qingfeng1; WANG Xiaoqing1; SHEN Guangqiu1
1Department of Chemistry,State Key Laboratory of New Ceramics and Fine Processing,Tsinghua University, Beijing 100084; China

Nanoparticle arrays have attracted enormous interest due to their size, shape, and period-dependent optical, magnetic, and ferroelectric properties. Nanosphere lithography (NSL) has been proved an inexpensive, inherently parallel, high-throughput, and materials-general technique for the fabrication of ordered nanoparticle arrays. The period of the nanoparticle array can be controlled by changing the diameter of colloidal spheres. The height of the individual nanoparticles is determined by the amount of material that is deposited through the colloidal monolayer mask. What makes NSL technique appealing is that the lateral feature size of the resulting nanoparticles is approximately one fifth of the diameter of the colloidal spheres. So far, there have been two main restrictions that have hindered wide applications of NSL on the fabrication of high-quality nanoparticle arrays. Firstly, the order of the resulting nanoparticle array is essentially dependent on the quality of the deposition mask, i.e. the colloidal monolayer. In most cases, a colloidal monolayer is formed on a solid substrate via the convection-driven evaporative self-assembly techniques in a liquid medium. Although the colloidal monolayer may hold a high-quality crystalline structure when it is in a wet state on the solid substrate, irregular cracks appear after the liquid is eventually evaporated. Secondly, the lateral feature size of the nanoparticles created using NSL is coupled with the diameter of the colloidal spheres. This kind of coupling, however, results in a constraint to study the size-dependent properties of nanoparticles in case colloidal spheres with various diameters are not available. In this work, we present an improved air/water interface self-assembly method to fabricate large-area and exclusively single layer latex colloidal crystal. The interstice size in the colloidal monolayer can be precisely manipulated by a subsequent in-situ annealing of the floating colloidal monolayer with a water-soluble organic solvent. Meanwhile, the mechanical strength of the colloidal monolayer is enhanced because colloidal spheres fuse together. As a result, large-area, transferrable, and high crystalline integrity colloidal masks with controllable interstice sizes for NSL application are achieved.

NNF 2138, Oral, Coating surfaces with metal nanoparticles, carbon nanotubes and inorganic nanowires: from catalysis to growth

Geng Junfeng1;Johnson Brian2
1Institute for Renewable Energy and Environmental Technologies, University of Bolton; United Kingdom
2Department of Chemistry, University of Cambridge;United Kingdom

As is known today, proper surface depositions of metal nanoparticles are currently of considerable appeals because of their importance as catalytic seeds for growth of nanotubes and nanowires, as quantum dots for fundamental exploration of physical problems, and as electron tunneling materials for application in the semi-conducting industry. This presentation will highlight the following two aspects: (1) Deposition of transition metal nanoparticles to make thin films. Several novel methods for the synthesis and characterization of chemically active metal nanoparticles have been developed. For example, we have found that nickel formate can serve as an ideal precursor for producing Ni nanoparticles of controlled sizes. Such nanoparticles can efficiently catalyze the growth of carbon nanotubes on different substrates. This merit has enabled us to produce high-quality single-walled and multiwalled carbon nanotube thin films for applications in renewable energy field. Growth of patterned carbon nanotubes has also been carried out on metal and semiconducting surfaces. In these cases, we have successfully developed a wet chemistry method for surface-bound growth of carbon nanotubes over a large area utilizing a micro-contact printing technique associated with PECVD deposition. (2) Metal nanoparticles and growth of inorganic nanowires on surfaces. Silicon nanowires could be used as a critical component for nanoelectronic devices because of their unique semiconducting properties. Recently silicon nanowires have been demonstrated to function as simple field-effect transistors, doped p-n junctions and bi-polar transistors. Here we demonstrate a catalytic growth of surface-bound Si nanowires and report their characterized nanostructure. Furthermore, we demonstrate an orientation-controlled surface growth of tin oxide (SnO) nanowires, together with the synthesis of fullerene (C60) nanowires. These activities arise from our fundamental interests in these materials and their important potentials for industrial applications.

NNF 2139, Poster, Microstructures and mechanical properties evaluation of ZrCN thin films

Tung Cheng-Yi1;Lee Jyh-Wei2; Kuo Chil-Chyuan3; Huang Sung-Hsiu4; Chan Yu-Chen5; Chen Hsien-Wei6; Duh Jenq-Gong7
1Department of Mechanical Engineering, Mingchi University of Technology, Taipei, Taiwan; Taiwan
2Department of Materials Engineering, Mingchi University of Technology, Taipei, Taiwan;Taiwan
3Department of Mechanical Engineering, Mingchi University of Technology, Taipei, Taiwan;Taiwan
4Gigastorage Corp.;Taiwan

Zirconium nitride thin film is characterized for its high hardness, good tribological property and low electrical resistivity , which makes it a popular material applied widely in industries. In this study, a series of ZrCN thin films with different carbon contents were prepared by the cathodic arc-evaporation (CAE) deposition method using different amount of N2 and C2H2 gases. The crystalline structure of coating was determined by a glancing angle X-ray diffractometer. The surface and cross-sectional morphologies of thin films were examined by a field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), respectively. A nanoindenter, scratch tester, HRC-DB and pin-on-disk wear tests were used to evaluate the hardness, adhesion and tribological properties of ZrCN thin films, respectively. It was concluded that the microstructure, gain size, hardness and tribological properties were strongly influenced by the carbon contents of ZrCN thin films in this work.

NNF 2140, Poster, Heat treating effects on the crystallization behavior and mechanical properties of Zr-based thin film metallic glasses

Chuang Ching-Yen1;Lee Jyh-Wei2; Li Chia-Lin3; Chu Jinn P.4
1Department of Materials Engineering, Ming Chi University of Technology, New Taipei City, 24301, Taiwan; Taiwan
2Center for Thin Film Technologies and Applications, Ming Chi University of Technology, New Taipei City, 24301, Taiwan;Taiwan
3Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, 10607, Taiwan;Taiwan
4Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, 10607, Taiwan;Taiwan

The crystallization behavior and mechanical properties of thin film metallic glasses (TFMGs) have attracted lots of attentions in recent years. In this work, two Zr-Ni-Al-Si thin film metallic glasses with and without nitrogen content were fabricated by co-sputtering process. The nitrogen was introduced during deposition using a plasma emission monitoring (PEM) control system.Three rapid thermal annealing treatment were held at T1、T2 and T3 temperature ,respectively ,in which 0.6TgTx were adopted. The microstructures of TFMGs before and after rapid thermal annealing were characterized by a grazing angle X-ray diffraction (XRD). The cross-sectional morphologies of annealed TFMGs were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface roughness of TFMGs was explored by atomic force microscopy (AFM). Nanoindenter and microscratch testers were adopted to evaluate the mechanical and adhesion properties of TFMGs before and after annealing . It was observed that the crystallization behavior and mechanical properties of TFMGs were affected by nitrogen content and suitable rapid thermal annealing process at appropriate temperature.

NNF 2144, Poster, Protruding design effect of poly gate on nanoscale NMOSFETs with advanced strain engineering

Chang-Chun Lee1;Chuan-Hsi Liu2; Hsiao-Hsuan Teng2
1Department of Mechanical Engineering, Chung Yuan Christian University; Taiwan
2Department of Mechatronic Technology, National Taiwan Normal University;Taiwan

With the mainstream of highly scaling the characteristic size of nano-transisters, the use of strain engineering has been demonstrated to have the benefits to meet the requirement of enhancing the device performance significantly. Actually, the effect of layout dependence on strained MOSFETs is greatly obvious. However, the discussion regarding the stress variation influenced by layout designs of MOSFETs with silicon based strain engineering is little. For the reason, this investigation focuses on the performance impact of the protruding design of poly gate on NMOSFETs with the combinations of Silicon-Carbon (SiC) stressor and tensile CESL. Strained effect resulted from lattice mismatched SiC with different carbon mole fraction and CESL are simulated using three-dimensional (3D) finite element analysis (FEA). A 100 nm width of narrow gate is utilized to enlarge the effect of foregoing concerned geometrical factor with an examined range from10nm to 3 μm. Under the considered situation of applying SiC stressor (the carbon mole fraction is 1.65 %) and tensile CESL (+1.1 GPa), the analytical results point out that the stress impact induced from SiC embedded source/drain stressor combined with tensile CESL could be regarded as a superposed production of individual magnitude. For SiC stressor, a significant reduction of stress in the direction of channel length from 411 MPa to 198 MPa is estimated as the protruding length of poly gate along the direction of channel width extends from 10 nm to 3 μm. It could be attributed to that a bending behavior increases with a more extension in the protruding length. Consequently, both vertical and transverse stresses become more compressive, respectively. On the other hand, the induced stress from tensile CESL has a competitive relation by the length proportion of poly gate in STI and active regions, separately. The analytic results indicate that about 40 % of maximum mobility enhancement occurs on this condition with a 50 nm protruding length in poly gate. Therefore, the predicted results reveal the present layout of NMOSFET devices would affect mobility gain through such strain engineering.

NNF 2151, Poster, Fabrication of Carbon Nano-Partition for Heat Dissipation on the Light Emitting Diode (LED) Modules

TSAI Jeff;
Institute of Optoelectronic Sciences, National Taiwan Ocean University; Taiwan

We demonstrated the fabrication of vertical standing carbon nano-partitions (CNPs) on various substrates by radio frequency sputter system. For such nano-carbon-material, the ultra large surface area which profit on the heat dissipation are also demonstrated within the LED modules. The experiment of measuring thermal resistance, the enhancement of conductive heat transfer has been confirmed. The heat transfer depends on the density of the CNP array. We also found that the heat transfer relate to the ambient pressure. The mean-free-path of air decreased with the pressure, and then enhances the heat exchange from CNPs to air. In addition, we coated silver thin film on the CNPs for improving the thermal conductivity. Silver coated CNPs shows the best performance in LED thermo management with the decrement of 18% in thermal resistance.

NNF 2155, Poster, Core-shell structured snowman-like microspheres coated with functionalized MWNT and their electrorheology: effect of solvent

ZHANG Ke;LIU Ying Dan; CHOI Hyoung Jin
Department of Polymer Science and Engineering, Inha University; Korea (south)

An effort was devoted to fabricate core-shell structured multi-walled carbon nanotube (MWNT)/ poly (methyl methacrylate) (PMMA) snowman-like nanocomposite particles via a simple physical adsorption process under ultrasonication. Initially, the non-spherical particles i. e. snowman-like PMMA particles as “core materials” were polymerized by a seed emulsion polymerization and MWNT as “shell materials” was modified with carboxylic acid functional groups on their side wall based on oxidation process. The functionalized MWNT was spontaneously adsorbed onto the surface of particles when dispersed in either distilled water or methanol without any surfactants. Under this way, the MWNT was confirmed to be well adsorbed onto particles surface by using scanning electron microscopy (SEM) and its adsorption state is considered to be determined by the solubility of solvent. Their electrical conductivity and thermal stability were found to be increased due to incorporation of the MWNT. In addition, electrorheological (ER) performance of the functionalized MWNT/snowman-like particles was also characterized, in which the particles dispersed in silicon oil exhibit fibrillated chains spanned within electrodes under an applied electric field. The yield stress as function of shear rate under various electric field strengths were studied via a rotational rheometer equipped with a high voltage supplier, finding that shear stress curves are fitted well with the Cho-Choi-Jhon model.

NNF 2164, Oral, Enhancing refractive index of sol-gel thin films by incorporating TiO2 and ZnO nanoparticles synthesized by chemical and solvo-thermal methods

Wu Yong Ling, Linda;
Singapore Institute of Manufacturing Technology; Singapore

Thinner and lighter spectacle lens is made of polymer with high refractive index up to 1.71, which considerably reduces the fatigue incurred by the user. However, a matching index coating is needed for the protection of the lens surface for prolonged life span of the lens. In this article, we report a transparent thin and hard coating made of silica based sol-gel coating with incorporated TiO2 or ZnO nanoparticles with matching refractive index to the lens. The TiO2 and ZnO colloids were synthesized by several chemical and solvo-thermal processes for selection of the smallest size and highest transparency to suit the critical lens application. It was found that TiCl4/Benzyl alcohol and ZnAC2/MeOH processes gave the smallest particle sizes of 44.97nm and 29.3nm for TiO2 and ZnO colloids respectively, while low temperature dissolution–re-precipitation (LTDRP) technique produced phase pure Rutile Titania. The crystal structures were confirmed by X-ray diffractometer (XRD). Particle size, Zetapotential, and Iso-electric point of colloids were measured by Malvern Zetasizer. The effect of nanoparticle size and concentration on the optical properties were studied and characterized by Ellipsometry and UV-VIS spectrophotometer. The effect of particle concentration and sol-gel coating parameters (dipping speed, coating thickness) on the scratch resistance of the coated lens was evaluated by pencil hardness and nano-indentation. The refractive index was increased from 1.45 to 1.70, optical transparency remained at 90%, pencil hardness 2H, and nano-indentation hardness of 0.9 GPa have been achieved. It was found that smaller particle size below 50nm and low particle concentration (below 10%wt in solid cured layer) are recommended.

NNF 2176, Oral, Tailoring the electrical and magnetic properties of nanogranular films for high frequency applications

Bai Feiming;Lu Guangduo; Zhang Huaiwu
University of Electronic Science and Technology; China

With the development of the electronic devices towards GHz operational frequency and ultrahigh degree of integration, soft magnetic films with excellent high frequency characteristics are desired as core materials for applications in magnetic components. The fundamental requirements for these films include high saturation magnetization, high natural ferromagnetic resonant (FMR) frequency and high permeability[1-2] In addition, high electrical resistivity also plays a critical role to reducing eddy current and improving quality factor of magnetic core at high frequency.[3] Nanogranular films consisting of magnetic metallic particles embedded in non-magnetic insulating matrix are one of the best candidates to meet all the requirements, which can be well explained by Hertz’s random anisotropy model.[4,5] However, it is challenge to reduce the size and spacing of magnetic nanoparticles while ensuring good insulating quality at high frequency. In current work, FeCo-Hf-O and FeCo-Si-O thin films were deposited on Si substrates using RF magnetron sputtering. Three techniques have been explored to tailor the electrical resistivity of nanogranular films while preserving excellent soft magnetic properties: (i) selecting insulating matrix with different dielectric constant; (ii) varying target composition and (ii) varying sputtering power during film growth. It was found that the electrical resistivity of the FeCo-Hf-O film decreases sharply from 9125 to 1890 micro-ohm.cm with increasing sputtering power from 50W to 200W, meanwhile, the saturation magnetization and the FMR frequency increase with increasing sputtering power, but then decrease when sputtering power exceeded 200W. The maximum value of saturation magnetization and FMR frequency were 20.5 kG and 3.2GHz, respectively. For FeCo-Si-O, the best thin films with saturation magnetization, FMR frequency and resistivityof 13.5 kG, 3.9GHz and 1200 micro-ohm.cm, respectively. The origin of different magnetic and electrical properties is explained based on microstructure analysis of X-ray diffraction and transmission electron microscopy. Reference: [1]. Y. Hayakawa, A. Makino, H. Fujimori, and A. Inoue, J. Appl. Phys. 81, 3747 (1997). [2]. L. Li, D. W. Lee, M. Mao, T. Schneider, R. Bubber, K. P. Hwang, Y. Min, and S. X. Wang, J. Appl. Phys. 101, 123912 (2007). [3]. D. S. Gardner, G. Schrom, F. Paillet, B. Jamieson, T. Karnik, and S. Borkar, IEEE Trans. Magn. 45, 4760 (2009). [4]. G. Herze, IEEE Trans. Magn. 25, 3327 (1989). [5]. G. Herze, IEEE Trans. Magn. 26, 1397 (1990).

NNF 2185, Poster, Preparation of optical microstructures with subwavelength periodicity based on solvent annealed colloidal monolayers at the air/water interface

Zheng Lu1;Geng Chong1; Yan Qingfeng1; Yan Qingfeng2
1Department of Chemistry, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University; China
2State Key Lab of Silicon Materials, Zhejiang University;China

Reduction of optical reflection is one of the main challenges for silicon-based optical and optoelectronic devices such as solar cells, displays and light sensors. Antireflective structures, which can act as high-efficiency absorbers, have attracted growing attention due to their wide applicability in optoelectronic devices. Among the main approaches to obtaining efficient antireflective structures, fabricating a subwavelength nanostructure with a period comparable to the wavelength of incident light is presently in a favourable situation depending on its suppression of reflectance in the wider ranges of both spectrum and incident angles of light caused by ‘moth-eye effect’. However, the construction of most antireflective subwavelength nanostructures at present is based on the conventional colloidal nanosphere lithography which is very expensive and requires the exploration of complex processing parameters. In this work, we demonstrate a novel method for fabricating optical microstructures with subwavelength periodicity based on solvent annealed colloidal monolayers at the air/water interface. Compared with the lithography technique extensively used in antireflection nanostructures, the new approach described here provides a cost-effective, simple and high-efficient processing for fabricating subwavelength microstructures. The subwavelength-sized features may have great potential as high-performance antireflection nanostructures which might be utilized in many fields such as photovoltaic devices, light-emitting diodes (LEDs), viewing glasses and other light-sensitive detectors.

NNF 2192, Poster, Free-standing Monolayer Colloidal Mask with Tunable Interstice Size for Nanosphere lithography

GENG Chong;ZHENG Lu; YU Jie; YAN Qingfeng; WANG Xiaoqing; SHEN Guangqiu1; SHEN Dezhong1
Department of Chemistry, Tsinghua University; China

Nanosphere lithography (NSL), which utilizes self-assembled colloidal crystal monolayers as masks to fabricate nanostructures with high uniformity over large areas, is a high through-put and low-cost method. Nanospheres can self-assemble into a hexagonally close-packed monolayer array. Afterwards, the hexagonal periodicity of the monolayers, which serve as a barrier for depositing, is transferred to the underlying substrate. The size and period of interstices between adjacent PS spheres determines the properties of the resultant nanostructure, such as optical and magnetic properties. Therefore, the quality of the colloidal mask is dominant in the fabrication of ordered nanostructures by using NSL. The deformation of colloidal spheres by heat, solvent swelling, or ion bombardment may result in a colloidal mask with tunable interstice size. However, colloidal monolayers need to be transferred to a desirable substrate prior to the mentioned treatment, and extra cracks will be inevitably induced during the deformation of colloidal spheres. In this paper, free-standing monolayer colloidal template with tunable pore size is prepared by the combination of self-assembly of polystyrene nanosphere (PS) at the air-water interface and chemical vapor deposition of silica. Water vapor around the colloidal crystal monolayer reacts with the SiCl4 steam introduced by nitrogen carrier gas to form silica. Consequently, it induces the formation of a continuous silica layer coating the surface of each PS sphere, which results in the shrinkage of the interstice between neighboring PS spheres. The fine modulation of interstice size can be achieved by controlling the flow rate of nitrogen carrier gas and the deposition time. Thus, the method provides a facile approach to the fabrication of transferrable, interstice-size-tunable, high-quality colloidal masks for NSL application.

NNF 2195, Poster, Columnar Co-rich Co-Pt grains with high perpendicular magnetic properties prepared at low temperature

Chen S.C.;
Department of Materials Engineering and Center for Thin Film Technologies and Applications, Ming Chi University of Technology; Taiwan

Granular Co80Pt20 nano-grains having perpendicular coercivity of 4.5 kOe and perpendicular squareness of 0.82 can be achieved by dc co-sputtering Co80Pt20 (25nm) film onto Ru(30nm)/Ag(100nm)/Glass substrate at ambient temperature. It is found that the Co80Pt20 film deposited directly onto Ru layer without Ag underlayer shows an in-plane magnetic anisotropy. This is because a fcc Ag (111) underlayer can promote hcp Ru (002) seed layer to well induce (002) texture in hcp Co80Pt20 magnetic layer, leading to a good perpendicular magnetic anisotropy of Co80Pt20 films. TEM cross-sectional images show that the columnar nano-grains with average width of 8 nm are observed in Co80Pt20 magnetic layer, which is in good agreement on observation of TEM plane-view images. When Post-annealed the Co80Pt20/Ru/Ag/Glass substrate multi-layer films in a vacuum of 1mTorr at a lower temperature of 300 °C for 30 min, both the perpendicular coercivity and perpendicular squareness of the film can be further increased to 5 kOe and 0.87 respectively, which has significant potential as perpendicular magnetic recording (PMR) media for ultra high-density recording.

NNF 2196, Poster, Microstructures and magnetic properties of L10 FePt films deposited onto NaCl-type films

Chen S.C.;
Department of Materials Engineering and Center for Thin Film Technologies and Applications, Ming Chi University of Technology; Taiwan

Single-layered FePt films of 30 nm thick with a perpendicular magnetic anisotropy are achieved by depositing the film onto heated Si(100) substrate at 620 °C. Its perpendicular coercivity, saturation magnetization and perpendicular squareness are as high as 14 kOe, 473 emu/cm3 and 0.96, respectively. The perpendicular magnetic anisotropy of the single-layered FePt film degrades when a 5-nm NiO film is introduced under the FePt films. Upon further increasing the thickness of NiO film to 10 nm, the perpendicular coercivity of the film decreases greatly to around 4 kOe. Compared with NiO underlayer, when a 10-nm MgO underlayer is introduced, the perpendicular coercivity of the FePt film is still as high as above 12 kOe. Furthermore, when the thickness of the MgO underlayer decreases to 5 nm, the perpendicular magnetic anisotropy of the single-layered FePt film can be further enhanced. Its perpendicular coercivity remains at 13.6 kOe, However perpendicular squareness increases significantly to 1. Auger electron spectroscopy (AES) analysis shows that Ni atoms diffusing into the FePt magnetic layer from the NiO underlayer is much greater than that of Mg atoms in FePt/MgO bilayer films. Ni atoms mainly react with Fe atoms to form NiFe compounds with soft magnetic properties, which results in a large decrease in perpendicular magnetic anisotropy and perpendicular coercivity of FePt/NiO bilayer films with thicker NiO underlayers.

NNF 2206, Poster, Characteristics of CrAlSiN+DLC coating deposited by lateral rotating cathode arc PVD and PACVD process

LUKASZKOWICZ Krzysztof;
Institute of Engineering Materials and Biomaterials, Silesian University of Technology; Poland

The coating system, nanocomposite CrAlSiN film and diamond-like (DLC)-based lubricant top layer is commonly used in a variety of applications, from tools for forming and stamping to high-performance cutting tools. The strong increase of the lifetime of the tools coated with CrAlSiN+DLC is mainly due to the higher hardness and resistance against brittle fracture of the nanocomposites. The paper presents the research results on the microstructure, mechanical and tribological properties of CrAlSiN+DLC coating deposited by lateral rotating ARC-cathodes (LARC) and PACVD technology on the X40CrMoV5-1 hot work tool steel substrates. The microstructure, morphology, phase identification, chemical state and tribological properties of the CrAlSiN+DLC coatings were analyzed by high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and ball-on-disk respectively. It was found that tested coatings have nanostructural character with fine crystallites, while their average size is less than 10 nm. The coatings demonstrated a dense and compact morphology. Basing on the XRD pattern of the CrAlSiN, the texture direction 〈311〉 is perpendicular to the sample surface. In sliding dry friction conditions the friction coefficient for the investigated elements is set in the range between 0.05-0.07. The investigated coatings reveals high wear resistance.

NNF 2213, Poster, Direct synthesis of CNT in aqueous solution at very low temperature.

Yang Chia-Hao;Lin Yan-Ru
Department of Materials Engineering/Center for Thin Film Technologies and Applications, Ming-Chi University of Technology; Taiwan

This study present a simple method to produce carbon nanotbue (CNT) in aqueous solution at very low temperature (85 °C). The aqueous solutions that contain urea and sodium hydroxide can first synthesize a basic unit: thin carbon nanoribbons. The evolution of the microstructures has been observed by high-resolution transmission electron microscopy (HRTEM, JEOL JEM 2100 LaB6). HRTEM images show the carbon nanoribbons can self-assembly to form ribbon type of graphite nanofibers , carbon nanorings, and CNTs, finally. The CNT can become thicker by sticking nanoribbons on the wall. No catalysis is used during the process. Possible growth mechanism of the CNT is proposed.

NNF 2216, Poster, Decoration of PbS nanoparticles on Al-doped ZnO nanorod array thin film with hydrogen treatment as a photoelectrode for solar water splitting without an extra transparent conducting oxide thin film

Hsu Chih-Hsiung;
Department of Chemical Engineering & Research Center for Energy Technology and Strategy; Taiwan

For most of photoelectrodes in the photoelectrochemical cells, the photoactive semiconductor layers are coated or grown on the transparent conducting oxide (TCO) thin films for collecting electron efficiently such as indium tin oxide (ITO) and fluorine-doped tin oxide (FTO). In this work, Al-doped ZnO (AZO) nanorod arrays thin film with hydrogen treatment is directly used as an ITO/FTO-free photoelectrode for solar water splitting because it possessed the functions of TCO thin film and photoactive 1-dimensional nanostructured semiconductor simultaneously. To enhance the absorption in the visible region, PbS nanoparticles are decorated on the AZO nanorods via successive ionic layer adsorption and reaction (SILAR) route. The PbS nanoparticles have a face-center cubic structure and their decoration does not destroy the 1-dimentional morphology of AZO nanorods. With increasing the cycle number of PbS nanoparticles decoration, the grain sizes of PbS nanoparticles become larger gradually which leads to a lower energy bandgap. When the cycle number is 20, a maximum photocurrent density of 1.65 mW/cm2 is obtained. This is about 55 times higher as compared to that before the decoration of PbS nanoparticles. The corresponding hydrogen generation efficiency is 0.91 %. This result is comparable to the other works concerning the PbS nanoparticles-decorated TiO2 nanostructured thin film with ITO or FTO as the substrate. This demonstrates that the AZO nanorod array thin film with hydrogen treatment is quite suitable as an ITO/FTO-free photoelectrode, which also makes the fabrication of photoelectrode simple and low-cost because the use of expensive rare metals can be avoided and the pre-fabrication of TCO thin film substrate is necessary no more. So, it has great potentials in solar water splitting after sensitization by quantum dots capable of visible light absorption.

NNF 2234, Poster, Catalyst properties of nickel and copper nano additives in porous polymer matrix after selective laser sintering

Shishkovsky Igor1;Morozov Yuri2; Bulanova Angela3
1Samara branch, Lebedev Physics Institute of Russian Academy of Sciences; Russian Federation
2Institute of Structural Macrokinetics and Materials Science (ISMMS);Russian Federation
3Department of Chemistry, Samara State University;Russian Federation

Optimal regimes of laser synthesis for three-dimensional porous membranes by selective laser sintering method were determined depending on laser influence parameters, metal-polymer powder compositions and fraction size of metal nano inclusions. As a metallic filler agent the copper ~ 50 micron, 70-120 nm and the nickel 15-200 nm were used. SEM equipped energy dispersive x-ray microanalysis are indicated about of relative stability of nano inclusions after liquid-phase laser sintering of polycarbonate. In the comparison the catalytic characteristics of micro- and nano- copper were studied by the gas chromatography dates of benzene hydrogenation reaction. It was shown that reaction velocity increases up to 2.5 times. We have studied low temperature oxidation of carbon monoxide and propane on nickel nano powders differing in particle size and extent of oxidation. The nano nickel with optimized characteristics has been shown to have a marked catalytic effect on these processes. The benefit for the understanding of catalytic properties of thin membraness in the form of Cu/Cu and Ni/NiO oxides, prepared by laser-assisted nanofabrication, was discussed in frameworks of perspectives for NEMS applications.

NNF 2238, Oral, Influence of Frequency and Duty Cycle in the Pulse Electroplating of Gold in Mesoporous Titanium Dioxide

Ong Duen Yang12;Zhao Wenbo1; Liu Qing3; Gan Chee Lip1; Leong Kam Chew2; Wong Chee Cheong1
1School of Materials Science and Engineering, Nanyang Technological University, Singapore.; Singapore
3Temasek Laboratories, Nanyang Technological University, Singapore.;Singapore

The surface of an insulator has to be coated for electroplating to occur, and hence, it is effectively plating on a conductive surface. This work presents the electroplating of gold (Au) into mesoporous titanium dioxide (TiO2) without any surface treatment on the mesoporous TiO2. Au nanoparticles with controllable sizes range from 50 nm to 500 nm were obtained. For pulse electrodeposition, effects of pulse amplitude, frequency, and duty cycle on the density of nucleation sites, particle size and its distribution has been investigated. We observed that the pulse electrodeposition has high density of nucleation sites because pulse electrodeposition enables nucleation occurrence on every pulse cycle. On the other hand, the metal salt arrival at the surface for reduction reaction is essential. Although the electroplating solution is able to penetrate into the mesoporous network, this penetration requires time. Hence, the delay in metal salt arrival causes the electroplating of gold into mesoporous TiO2 to obey a progressive nucleation mechanism. In short, nucleation and growth of Au in mesoporous TiO2 is diffusion controlled reaction with the metal ion (Au+) as the limiting steps for gold nucleation.

NNF 2239, Oral, Fabrication and modification of magnetizatic exchange bias system

FA Tao;NIAN Qinggong; CHENG Fengfeng; PAN Huiping; LI Lin; YAO Shude1
State Key Laboratory of Nuclear Physics and Technology,Peking University; China

Exchange bias(EB)is an important and unique magnetic phenomenon in modern magnetism. It links magnetic interactions between ferromagnetic(FM) and anti-ferromagnetic(AFM) materials, which results in an enhancement of coercivity and a shift of hysteresis loops along the applied magnetic field axis after field cooling. Exchange bias effect has already shown great potential applications in some spintronic devices such as spin valve and magnetic tunnel junction. We applied and developed various methods to build the Ni/NiO or Co/CoO EB system: • Molecular beam epitaxy (MBE) grown Ni film on MgO substrate followed by O+ ion implantation. • Sputtering deposited Ni or Co film on Si substrate followed by O+ ion implantation. • Ni+ and O+ dual ion beams sputtering on Si substrate to build Ni/NiO. To find the most optimized growth condition, we alter different experimental parameters, i.e. the implantation energy, dose, shelter film, post-annealing to systematically study the influence on the final exchange bias effect. Multi-implantation and swift heavy ion irradiation are also employed. The micro-structure properties are characterized by RBS/C, SR-XRD, TEM and XPS, while magnetic properties are studied by VSM, SQUID and MOKE. Combining the structure and magnetic properties, we conclude that the size of the AFM particles formed by oxygen implantation in our system is not homogeneous and shows a Gaussian distribution. As the range distribution of the implanted oxygen ion, their Neel temperature drops below room temperature under the influence of size effect. As a result, the exchange bias field of implanted Ni/NiO system exhibits the dependence on field cooling temperature. We also get the prodigious result: in the new EB system fabricated by multiple energy and dose oxygen implanted in Ag/Ni films, the exchange field is 10 times higher than that by single energy implantation.

NNF 2240, Poster, Effect of Content on Microstructure and Dielectric Properties of Polyimide/BaTiO3 Nanocomposite Films

Chen Minghua1;Yin Jinghua2; Liu Xiaoxu1; Feng Yu1; Lei Qingquan
1School of Applied Science , Harbin University of Science and Technology; China
2Key Laboratory of Engineering Dielectric and Applications (Ministry of Education) , Harbin University of Science and Technology;China

With the development of the electronic industry, the search for the excellent dielectric materials has stimulated important research activities. In this paper, PI/BaTiO3 films were prepared by in-situ method and their microstructures were studied for the first time by synchrotron radiation small angle X-ray scattering (SAXS) technique. SAXS results indicate the average radius of the nanoparticles in hybrid films distribute from 55 nm to 90 nm, which are consistent with the observation from SEM. The results of SAXS showing the positive deviation that do not conform to the Porod theorem. There is fluctuation of electron density in the materials and the distribution of inorganic is uneven, which suggest that there is no obvious interface layers. Meanwhile, nanoparticles also have mass fractal and surface fractal structure, respectively, the surface fractal dimension rises while mass fractal dimension decreases, showing that doped nanoparticles become looser with the increase of hybrid PI components and the surface of nanoparticles becomes rougher. Corresponding, the electrical properties of the films which are some key parameters were tested. The dielectric constant and loss tangent increase with the content increase, and the breakdown strength decrease, but still with high dielectric permittivity (18), high breakdown strength (60kv/mm), which is anticipated for future dielectric materials with the excellent properties.

NNF 2241, Poster, The Structural Characteristics and Dielectric Properties of Multilayer PI/MMT Nanocomposite Films

Yin Jinghua2;Bu Wenbin1; Tian Fuqiang1; Chen Minghua1; Liu Xiaoxu1; Kong Yunan1; Feng Yu1
1School of Applied Science , Harbin University of Science and Technology; China
2Key Laboratory of Engineering Dielectric and Applications (Ministry of Education), Harbin University of Science and Technology;China

Polymer based inorganic nanocomposite dielectrics have drawn much interest in the field of electric and microelectronics due to its excellent electrical, thermal and mechanical properties. MMT(Montmorillonite)is a kind of typical silicate with layered structure, whose component and structure are similar to mica with excellent corona performance. The three layers structure films (PI+MMT/PI/PI+MMT) were designed which maybe play the complementation roles in some dielectric properties because of two distinct structures existing in the three layer films. The films with different component of MMT were prepared by in-situ polymerization process in this paper. The dependence of MMT concentration on the dielectric properties was investigated in this paper. Dielectric properties were measured by broadband dielectric spectrometer and the system of corona resistance. The microstructures of the films are observed by SEM. The experimental results show that the films are made up of three layers, pure PI in middle and PI+MMT in two sides, and MMT change the structure of PI and form schistose texture resisting discharge. The cross section of PI layer is flat and that of PI/MMT is coarse with smaller size schistose texture (500nm-5m). With the MMT component increasing, the permittivity become bigger and dielectric loss increase obviously in the range of low frequency (10-3~100Hz), corona aging lives are longer than that PI, especially, when the MMT component is above 5%. The breakdown strength decreased with the MMT component increasing. Compared with the single layer film, three layer films include two interfaces, which are on the sides of pure PI, containing a lot of defects and traps. The distribution of MMT particles, the states of interface (phase and layer) affected electron migration, which affected the dielectric properties of films, and then. The researches show that the corona aging life and dielectric properties can be enhanced by designing the multilayer PI/MMT nanocomposite films.

NNF 2249, Oral, Atomic scale investigation of temperature effects on Graphene growth on Cu foil and Fe foil

arab zeinab;abdolahi zahra; ghoranneviss mahmood
Plasma physics research center, Science and research branch, Islamic Azad University, Hesarak-Pounak, Tehran, Iran; Iran

We have investigated the effects of temperature on chemically vapor deposited graphene layers on Cu and Fe foils at the atomic scale using SEM,TEM ,AFM and Raman spectroscopy. Low temperature deposited graphene layer on Cu foil (~400°C)exhibited striped Moirre pattern which in turn indicate a relatively weak interaction between graphene layers and Cu foil. However, for the case of deposited graphene layer on Fe foils electronic coupling between layers didn’t occur even at 800°C. detail of results will be discussed in full paper.

NNF 2252, Oral, Electrical properties and Microstructure in three-component polyimide/ TiO2-MMTnanocomposite films

Liu Xiaoxu123;Yin Jinghua2; Chen Minghua2; Liu Erjia1
1School of Mechanical & Aerospace Engineering,Nanyang Technological University; Singapore
2School of Applied Science, Harbin University of Science and Technology;China

Novel polyimide (PI)-matrix composite films containing inorganic nanoparticles nano-TiO2 and layered montmorillonite(MMT) have been fabricated by employing in situ polymerization and their information on microstructure were investigated by synchrotron radiation small angle X-ray scattering (SAXS), wide-angle X-ray diffraction (XRD) and Scanning electron microscopy (SEM) technique. Meanwhile, the effects of content on the volume conductivity, loss tangent, permittivity and breakdown field strength are analyzed. A proposed model is used to explain different structures of the polyimide/TiO2-MMT films and dependences of electrical properties of the nanocomposite films on microstructure. The results shown that the introduction of a small amount of TiO2 and MMT also led to improvement breakdown field strength of nanocomposite showed a maximum value at the inorganic content of 5 wt%, which was 10% higher than that of two-component PI/TiO2 nanocomposite films. The information of microstructure indicates that not only there are obvious interface layers between the organic and the inorganic phases, but also TiO2 and MMT both were homogeneously dispersed in the nanocomposite films and played a coordination role. This study may provide a useful method to prepare polyimide-based nanocomposites with improved properties.

NNF 2254, Poster, The Properties and microstructure of Polyimide/Nano-TiO2 Hybrid Films with novel sandwich structures

Liu Xiaoxu123;Yin Jinghua2; Chen Minghua2; Liu Erjia1
1School of Mechanical & Aerospace Engineering,Nanyang Technological University; Singapore
2School of Applied Science, Harbin University of Science and Technology;China

Polyimide( PI)/Nano-TiO2 hybrid films with novel sandwich structures were prepared by in situ polymerization method. Before addition, Nano-TiO2 particles were firstly modified with coupling agents. The microstucture, electrical and mechanical properties of hybrid films were characterized and investigated. Results indicated that Nano-TiO2 particles were homogeneously dispersed in the PI matrix. The electrical isolation and mechanical properties of PI/nano-TiO2 composite films with 5% content were the best. The breakdown field strength and volume resistivity of PI composite film with novel sandwich structures were 216.5 (KV/mm) and 1.091×1017 (Ω.cm) which were 26.3% and 11.5% higher than monolayer PI composite film, respectively.

NNF 2257, Oral, Mesoporous films modified with polyvinylpyrrolidone blended sol-gel TiO2 for dye-sensitized solar cell

Huang Po-Chun;Chen Tsan-Yao; Lin Tsang-Lang
Department of Engineering and System Science, National Tsing Hua University; Taiwan

Polyvinylpyrrolidone (PVP) blended TiO2 synthesized via sol-gel process was successfully incorporated with a commercial TiO2 powder, Degussa P25. Different amounts of PVP blended TiO2 sol (10 %, 20 % and 30 % to P25 in molar ratio) were mixed with P25 to form the uniform pastes. After calcination, the spin-coated mesoporous films were used as the anodes of dye-sensitized solar cells (DSSCs). Among these anodes, the 20% sol-added 10 μm film offered the highest energy conversion efficiency (η) of 5.02 % with a short circuit photocurrent density (JSC) of 12.34 mA/cm2 as compared with that of the traditionally prepared P25 film under the same thickness (4.35 % and 9.53 mA/cm2). The photocurrent density is enhanced by the higher surface area obtained from the additional PVP blended TiO2 with the smaller particle size, and the overall efficiency is improved.

NNF 2265, Oral, An electroless deposition method for the synthesis of magnetic cobalt-reduced graphene oxide nanocomposites

WANG Yan1;ZHAO Yan1; SU Yuqin1; ZHANG Li2
1School of Materials Science and Engineering, Beihang University; China
2School of Mechanical Engineering and Automation, Beihang University;China

Since first successfully separated from graphite by micromechanical cleavage, graphene has emerged profuse interests of researchers all over the world, owing to its extraordinary electrical, thermal, and mechanical properties. This single-layer carbon material is regarded as a significant substitute in fabrication of transistors, integrated circuits, solar cells, chemical sensors and others. Therefore, modified graphene and graphene based nanocomposites were synthesized for different applications. Among them, inorganic nanoparticles (NPs) such as metal, metal oxide and sulfide have been decorated on the surface of graphene sheets for applications as catalysts, biomaterials, semiconductors, magnets and etc. However, most of those metal/graphene nanocomposites were synthesized from graphene oxide (GO) via in-situ method, in which reduced graphene oxide (RGO) was obtained during the generation of metal nanopaticles. In our recent work, we synthesized nanocomposites of cobalt nanoparticles decorated on RGO sheets (Co-RGO) by a multi-step electroless deposition process. X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to demonstrate physical, structural and chemical characterization of Co-RGO. It is shown that a uniform deposition of CoNPs can be obtained more facilely, with the help of catalytic Pd nanopaticles (PdNPs) and the reductant sodium hypophosphite. At the same time, graphene oxide sheets, the substrates, were also reduced. The magnetic hysteresis loop of as-synthesized sample indicates Co-RGO nanocomposites were endowed with soft magnetism and high saturation magnetization, which can be used as nanomaterials in magnetic separation, microwave absorbing, magnetic catalysts and many other applications.

NNF 2272, Invited Lecture, Oxidization resistance composite coating for supper high temperature Nb-based alloy sheet

Li Yibin;
Harbin Institute of Technology; China

Nb-W-Mo supperalloy has attracted more and more attention due to its excellent mechanical properties at supper high temperature. However, its weak oxidization resistance restricts the wide application. In this paper, the oxidization resistance silicides coating on the Nb-W-Mo sheet surface was prepared by the slurry method. The main phase of the coating is NbSi2 together with minority of Nb5Si3 and Ti5Si3. The surface microstructure of the coating is loose and inner is dense, between which there was stable transition layer. The elevated temperature tensile strength of the Nb-W-Mo sheet with silicides coating shows that the silicides coating could reduce the strength of the sheet. The oxidation kinetics of the silicides were also examined at 1100℃, 1300℃, 1500℃, and we found that the oxidation kinetics follows the parabolic rate law. The oxidation products were Nb2O5, SiO2 with minority of TiO2 that restraining the growth of Nb2O5, which effectively improves the oxidation resistance property.

NNF 2276, Oral, Effect of Anionic Nanoclay for Dye-Sensitized Solar Cell Application

Wang Xiu1;Deng Ran1; Wong C.C.1; Kulkarni Sneha A.12
1School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798; Singapore

Quasi-state electrolytes applied in Dye-sensitized solar cells (DSSC) are heavily researched and reported nowadays due to their ability to address the volatility issue. Here we report the use of anionic nanoclay as gelator to assist the formation of gel electrolyte which then was applied in DSSC. Three different clays with NO3-, CO32-, SO42- respectively are synthesized. Gel formation when nano-clay is added into liquid electrolyte is confirmed. Clay powders with different anions are studied by FESEM, BET, XRD and XPS to understand the factors that influence the interaction with I-/I3-. The change in interlayer distance is investigated by dissolving clay powders in acetonitrile to simulate the real situation in gel electrolyte.The experiments shows the presence of I-/I3- in the clay. On-device test of DSSC supports the anions effect; 7.4% efficiency of DSSC with nanoclay gel electrolyte is achieved compared with 6.88% of DSSC with liquid electrolyte.

NNF 2282, Poster, Influence of the modification of porous α-Al2O3 substrate on the hydrogen permselectivity of Pd/α-Al2O3 composite membrane

Tsai Ting-Kan;
Department of Materials Science and Engineering, National Formosa University; Taiwan

Three Pd/α-Al2O3 composite membranes with modified and unmodified porous α-Al2O3 substrates were prepared by electroless plating. The γ-Al2O3 modified coatings with and without Pd complex were obtained by using sol-gel method and coated on α-Al2O3 substrates by dip-coating. These composite membranes were characterized by SEM, XRD and EDS. Additionally, their hydrogen permeance and H2/N2 selectivity were determined in a home made gas permeation set-up at 623-773 K and pressure differences of 30-70 psi. The hydrogen permeance and H2/N2 selectivity of the γ-Al2O3 coated α-Al2O3 substrates were nearly the same as those of unmodified α-Al2O3 substrate at varied temperatures and pressure differences. However, the hydrogen permeance and H2/N2 selectivity of the Pd composite membrane with Pd-embedded γ-Al2O3/α-Al2O3 substrate were better than those of Pd composite membranes with γ-Al2O3/α-Al2O3 and unmodified α-Al2O3 substrates. A permeance of 1.05 ×10-8(mol/m2•s•Pa) and H2/N2 selectivity of 2200 were obtained at 723 K for the Pd composite membrane with Pd-embedded γ-Al2O3/α-Al2O3 substrate.

NNF 2289, Poster, The modulated structure and mechanic properties of VAlN coatings prepared by reactive magnetron sputtering

Zhu Ping;Ge Fangfang; Huang Feng
Ningbo Institute ofMaterial Technology and Engineering, Chinese Academy of Sciences; China

Vanadium nitride (VN) coating have been attracted a lot of attention for its lower coefficient of friction than titanium nitride (TiN) in a wide temperature range[1]. VN has not been studied as popular as the TiN, due to its low hardness[2]. The weakness can be improved by the incorporation of transition element into the coating, because it will form new phase and change the microstructure. However, hardly have studies been carried on the microstructure and mechanical properties of VAlN coating. This paper gives an attempt to prepare VAlN coatings and study the relation between the microstructure and the mechanic properties. Vanadium aluminum nitride coatings with composition of V1-xAlxN (x=0.43, 0.56) were prepared by reactive magnetron co-sputtering at 573K. The microstructure of both coatings was characterized by field emission scanning electron microscope (FE-SEM) and transmission electron microscopy (TEM). Mechanical properties of the coatings were investigated using nanoindentation performed on a MTS nanoindenter XP system. Table 1 shows the results of the mechanical properties of the coatings. Hardness and Young’s modulus of V0.44Al0.56N are 37GPa and 396GPa which are much higher than that of V0.57Al0.43N. Evidence from the plan-view TEM showed that the both coatings are modulated dual-phase structure, but there are obvious differences between them. There are also significant differences in FE-SEM investigation between the two coatings. The V0.57Al0.43N coating is columnar structure of cross-section and uniform granular domains on the surface, whereas the V0.44Al0.56N coating shows rather dense structure on both the cross-section and the surface. This suggests that densification coating can be obtained by addition of Al. Certainly, the compact and uniform structure has positive effect on the mechanic properties. A discussion of the relation between microstructure and mechanical properties is resolved. Table.1. Hardness and Young’s modulus of V1-xAlxN coatings V1-xAlxN Hardness (GPa) Young’s modulus (GPa) x=0.43 22 257 x=0.56 37 396 Reference: [1] G.Gassner, et al., A new low friction concept for high temperatures: lubricious oxide formation on sputtered VN coatings[J]. Tribology Letters, 2004, 17: 751 [2] H. Holleck, Materials selection for hard coatings[J]. Journal of Vacuum Science and Technology A, 1986, 4: 2661-2669

NNF 2294, Oral, Effects of Ordered Macroporous Structure on Their Eletrochromic Properties of 3DOM Tungsten Oxide Films

Li Yao1;Zhao Jiupeng2; Yang Lili3
1Center for Composite Materials, Harbin Institute of Technology; China
2School of Chemical Engeering and Technology, Harbin Institute of Technology;China
3School of Transportation Science and Engineering, Harbin Institute of Technology, Harbin, 150090, P.R. China;China

Electrochromic performance of tungsten oxide (WO3) has received extensive attention due to their applications in smart windows, spacecraft thermal control and military field et al. Here three-dimensional macroporous (3DOM) tunsten oxide films were fabricated through template-assisted sol-gel method and the effect of porous structure, pore size and thickness of 3DOM tungsten oxide films on their electrochromic performance were studied. Both improvement in IR region and suppression in visible region were clearly shown in optical modulation due to the introduction of ordered macroporous structure. The 3DOM structure is also very helpful for the diffusion of ions into the materials, which decreases the electrochromic response time. With the pore size decreases, the electrochromic performance was improved because of the abundant pore structure which leads to the more absorption of lights. However, the small pore size is also adverse for the formation of macroporous structure, which decreases the electrochromic performance. While with the increase of film thickness, the opportunities of ion diffusion decrease because of the weaking of electric field. It is also found that the optical density and coloration efficiency were significantly reduced because of the limited absorption of tungsten oxide. These experimental results reported here highlights the potential applications of macroporous electrochromic materials as a highly efficient basic material for fast IR electrochromic devices.

NNF 2295, Oral, Aluminum Nanoisland Films Formation under the Electron Irradiation of the Sapphire Surface

Zykova Ekaterina;Khaidarov Abdusame; Ivanenko Il'ya; Gainullin Ivan
Moscow State University; Russian Federation

The controlled fabrication of nanostructures with arbitrary shapes and defined chemical composition is of great interest because of the special properties exhibited by these materials and their potential applications in electronics, optoelectronics, electrocatalysis, and thin film coatings. In the present work we consider the possibility of use electron stimulated desorption (ESD) for the fabrication of structures on the nanometer scale on the surface of solids. It is known that low-energy electron bombarding of the binary compound surface may lead to emission of its components [1]. This phenomenon is observed for different types of materials such as oxides, alkali and alkali-earth metal halides. The more intensive ESD of anions can cause surface metallization and formation of nanoisland metallic film [2]. The aim of this study was experimental investigation of the ESD rate and formation of metallic islands on the surface of Al2O3 single crystal under low energy electron bombardment (E= 1—3keV) at the different sample temperature (20-320C). For estimation of ESD rate we used the method based on the dependence of the surface composition on the dosage of the electron irradiation. The surface composition was determined by Auger electron spectroscopy method. The metallic islands formed on the surface due to the electron irradiation were observed using atomic-force microscope (AFM). To reveal the optimal parameters for the nanoisland fabrication we investigated the dependence of the average size and density of metallic islands on the dosage and the energy of electron bombardment and sample temperature. It was found that Al islands of spherical form and diameter varied from 50 nm to 100 nm distributed irregularly on the Al2O3 surface. 1. Desorption Induced by Electronic Transitions DIET V (Springer Series in Surface Sciences 31, Springer-Verlag, Berlin, 1993. 2. M. Reichling, R. M. Wilson, R. Bennewitz, R. T. Williams, S. Gogoll, E. Stenzel, E. Matthias. Surface Science, 366 (1996) 531-544.

NNF 2301, Poster, Preparation and Characterization of La0.5Sr0.5CoO3 Thin Films via Sputtering Technology

Lee Shin;Hu Yi
Department of Materials Engineering, Tatung University; Taiwan

La0.5Sr0.5CoO3 (LSCO) thin films were grown on Si (111) substrates using radio frequency (r. f.) magnetron sputtering technology under controlled Ar/O2 gas flow. The LSCO films were annealed at 700 °C for 1 hour in air and their structural and electrical properties were investigated. X-ray diffraction analysis showed that the LSCO film was preferred (110)/(104) orientations. The work function of the thin films was about 5.87 eV determined from ultraviolet photoelectron spectroscopy (UPS) and no apparent change was observed with different Ar/O2 sputtering gas flow. The LSCO thin film is a p-type semiconductor and its energy gap (Eg) is about 0.603 eV. The conductivity of the thin films is affected by the Ar/O2 sputtering gas flow and show lowest resistivity with Ar/O2 ratio of 2.

NNF 2307, Poster, Methyltrimethoxysilane/tetraethoxysilane/methacyloxypropyltrimethoxysilane hybrid abrasion resistant coatings on polycarbonate

CHEN Yuhong;ZHAN Maosheng
School of Materials Science and Engineering, Beihang University; China

Hybrid coatings based on methyltrimethoxysilane (MTMS) were synthesized and applied on the polycarbonate (PC) for improvement of abrasion resistance. The coatings were prepared through the sol–gel process with MTMS as organic source, tetraethoxysilane (TEOS) as the inorganic network percursor, and methacyloxypropyltrimethoxysilane(MEMO)as a silane coupling reagent between the organic and inorganic phase. Fourier transform infrared (FTIR) spectra show that the cross linked network structure of Si-O-Si formed due to the hydrolysis–condensation reactions of alkoxy groups in the sol. The effect of components on the optical properties, pencil hardness, adhesion properties and the abrasion resistance of the coatings were investigated. The optical tests show that most coated PC samples had a little higher transmittance than pure PC. The adhesion tests reveal that the hybrid coatings MTMS/TEOS/MEMO possessed better adhesion than the MTMS/TEOS or pure resin from MTMS and demonstrate that the incorporation of MEMO with MTMS and TEOS can significantly improve the adhesion between the coatings and PC because the MEMO acts as a coupling agent between the organic and inorganic moieties in the final coating network. The abrasion tests indicate the MEMO/TEOS/MEMO coatings had higher hardness and much better abrasion resistance than pure organic resin from MTMS or MTMS/TEOS coatings. TEM and SEM tests also demonstrate that MTMS/TEOS/MEMO coatings can improve the abrasion resistance of PC effectively.

NNF 2309, Poster, Investigations of anomalous luminescence properties of porous anodic alumina on Si substrate with metal interlayer

Fang Chia-Hui;Wang Jen-Cheng; Chen Hung-Ing; Nee Tzer-En
Graduate institute of electro-optical engineering, Department of Electronic Engineering, Chang Gung University,; Taiwan

Porous anodic alumina (PAA) films produced by the anodization technique have a nanoscale porous structure in mass production and the pore height and diameter are controllable. In this study, we investigated the effect of current density on luminescence properties of PAA films. Metal interlayer was observed to have significant influences on the properties of PAA films. We used highly pure Al film (about 2.0 μm) was deposited on the p-type silicon substrate coated with a Ti and W metal interlayer (about 300 nm) by radio frequency sputtering. A layer of thin Ti and W film was sandwiched between a silicon substrate and an Al film to form the Al/Ti/Si and Al/W/Si structure. The anodization was carried out in 0.3 M oxalic acid solution at a temperature of 5 C, a voltage of 40 V for about 50 nm pores in diameter. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) was used to analyze the carrier recombination and investigate the effect of current density distribution PAA films on Si substrate with metal interlayer. The current densities of PAA/Ti/Si and PAA/W/Si structures both were higher than one of PAA/Si structure. Further, the pore-widening experiments in phosphoric acid have shown that the rate of growth of the oxide layer increases with increasing current density. We also have observed the different metal interlayer to the influence of the material properties of PAA films. From the x-ray diffraction experiment, it was been found that PAA films with higher current density have more aluminum oxide in the inside different substance structure. Based PL and TRPL experimental results, the PL intensity and carrier lifetime of F+ center gradually decease when a current density rising. It was attributed to that oxygen will make up the oxygen vacancy of aluminum oxides inside and reduce F+ defect during re-crystallize process.

NNF 2313, Poster, A Study of the nano graphite sheets/polypyrrole/EVA Nanocomposites for Electromagnetic interference Shielding

Chi-Yuan Huang;
Department of Materials Engineering, Tatung University; Taiwan

In this study, the expanded graphite (EG) which exfoliated to form the nano graphite sheets (NGS) via ultrasonic treatment was produced by H2SO4-GIC. The polypyrrole (PPy) which was absorbed on the NGS was synthesized by chemical oxidative polymerization with cetyltrimethylammonium bromide (CTAB) as a surfactant to prepare the PPy-NGS composite. As the cationic surfactant CTAB (0.01 mole) was added into the PPy-NGS chemical oxidative polymerization process, the PPy was dispersed and attenuated by surfactant in the process. It was found that a uniform composite was formed with PPy absorbing homogeneously on the NGS by SEM. The conductive fillers of PPy-NGS with the ethylene–vinyl acetate (EVA) were blended to form polymeric composite (PPy-NGS/EVA) for electromagnetic interference shielding. SEM shows that the thickness of PPy-NGS was obviously increased with increasing PPy content. The PPy-NGS can enhance the conductive network in the PPy-NGS/EVA composite. For this reason, the EMI SE of the PPy-NGS/EVA composite was improved obviously from 7 dB to 35 dB.

NNF 2322, Poster, Characterization of CrZrN nanocomposite films on Cu-alloyed ductile iron with an electroless nickel interlayer

HSU Cheng-Hsun1;HUANG Kuan-Hao1; KUNG Shu-Chi1; LIN Chung-Kwei2; HO Wei-Yu3
1Department of Materials Engineering, Tatung University; Taiwan
2College of Oral Medicine, Taipei Medical University;Taiwan

This study utilized electroless nickel (EN) as an interlayer, then coated CrZrN nanocomposite films on Cu-alloyed ductile iron by cathodic arc evaporation method. The coating morphology and structure were analyzed using SEM, XRD, and TEM. Moreover, Rockell indentation, nano-indention and ball-on-disc tests were performed to explore the properties of the coated specimens consisting of adhesion, hardness, elastic modulus, and friction coefficient, respectively. The results showed that EN was an amorphous structure while CrZrN film was CrN/ZrN nano-multilayered crystallize. As compared with single EN or CrZrN film, the CrZrN nanocomposite film with an EN interlayer exhibited a better adhesion strength (HF1), higher hardness (31.1 GPa), and higher elastic modulus (256.4 GPa). In particular, the iron after the EN/CrZrN duplex coatings remarkably reduced the friction coefficient from 0.78 to 0.38.

NNF 2323, Oral, Optical properties of InGaN/GaN MQWs LED patterned with 1D Plasmonic nanoparticle grating.

Ruan Da-Ge;Kung Wen-Ting; Wang Chih-Ming; Tzeng Shien-Der; Ni I-Chi
Institute of Opto-electronic Engineering, National Dong Hwa University, Hualien, 97401 Taiwan, R.O.C; Taiwan

In this paper, the polarization dependent optical properties of GaN one dimensional (1D) grating coated with Au nanoparticle are investigated using dark field angle-resolved photoluminescence (ARPL) spectrometer. The light emitting diode (LED) wafer was grown using metal organic chemical vapor deposition (MOCVD) technology. The GaN film is grown on the c-face (0001) 2-inch diameter sapphire substrate. The total thickness of the GaN epitaxy layer, including the nucleation layer, buffer layer, n-GaN, MQWs, electron blocking layer and p-GaN and so on, is about 5m. The peak wavelength of the GaN wafer is designed to be 460nm. An 1D grating was fabricated on the GaN film by using e-beam lithography and inductively coupled plasma (ICP) dry etching techniques. The 1D grating operate outside the photonic bandgap (PBG) spectral range acting as a diffraction grating placed close to the multi-quantum-wells (MQWs) for increasing the light extraction efficiency of LEDs and modulating the out-coupled far-field distribution. The light extraction efficiency of the GaN grating without coated with Au nanoparticle is TE-polarized dominated. Our previous results show that the GaN plasmonic grating with fine roughness suffers from surface plasmon (SP) heat dissipation. As a result, the extraction efficiency is limited. Nevertheless, as the GaN grating was coated with Au nanoparticle monolayer, the light extraction efficiency becomes TM-polarized dominated. It is because the Au nanoparticle plays a role of a SP scatter for scattering the coupled SP into free-space. The PL signal of TM-polarized light is about 1.3 fold higher than that of TE-polarized light for the GaN coated with Au nanoparticle monolayer.

NNF 2351, Oral, Improved method of electroless plating of Fe on the surface of hollow glass microspheres and its electromagnetic properties

Shen Xionggang;Zhao Yan; Zhu Lei; Su Yuqin
School of Material Science and Engineering, Beihang University; China

Electroless plating was used to plate Fe on the surface of the hollow glass microspheres with NaH2PO2•H2O and KBH4 as reducing agent respectively, and the CoreShell structure Fe/microspheres composite with conductivity and magnetic properties was prepared. FESEM and EDS was used to investigate the surface morphology and composition of the CoreShell structure Fe/microspheres. The result showed that the plating result with conventional NaH2PO2•H2O as reducing agent was poor with hardly any Fe on the surface, meanwhile, the coated Fe on the surface of the microspheres could reach 60% when KBH4 was used as reducing agent, and moreover, the process of electroless plating could be simplified because the the activating process could be left out. The electromagnetic properties and the magnetic properties of the CoreShell structure Fe/microspheres prepared with KBH4 as reducing agent was studied by vector network analyzer (VNA) and vibrating specimen magnetometer (VSM) and its wave absorption curve was calculated. The result showed that the electromagnetic loss (10-18GHz) was significant, and the reflectivity could reach -5.4dB when the frequency was 14.4GHz, besides, relatively high coercive force and good magnetic properties revealed its potential application as wave absorbing material.

NNF 2353, Poster, Zinc Oxide/Carbon Nanotubes Hybrid Films

Abdul Razak Faridah;
Physics Department, University of Malaya; Malaysia

Films of ZnO/CNT were fabricated on metallic (Ag, Cu, Al) substrates using the electrophoresis technique. Two different techniques were employed. Firstly, synthesis of ZnO/CNT mixtures films were fabricated by ac electrophoresis of mechanically mixed ZnO nanoparticles and dispersed CNT. Secondly, ZnO was synthesized mechanochemically in the presence of CNT and dc electrophoresis was used to fabricate the films. The ZnO/CNT mixtures and the films fabricated were characterized using field emission scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy and x-ray diffraction analysis. Field electron emission behaviour of the films was also investigated. Results of these measurements will be presented and discussed.

NNF 2355, Oral, Influence of Thermal Heating on Diamond-like Carbon (DLC) Film Properties Prepared by Filter Cathodic Arc

Khamnualthong Nattaporn1;Siangchaew Krisda2; Limsuwan Pichet3
1Department of Physics, King Mongkut’s University of Technology Thonburi, Bangkok, 10140; Thailand
2Western Digital (Thailand) Co.Ltd, Ayutthaya, 13160;Thailand
3Thailand Center of Excellence in Physics, CHE, Ministry of Education, Bangkok 10400;Select your country!

Diamond-like carbon (DLC) films were deposited on magnetic recording heads using filter cathodic arc (FCA). The deposited thickness was on the order of few nanometers. The effects of heating temperature on microstructure, chemical bonding, optical property, and films wear resistance of the resulting films were studied in this study. Gross changes were observed in the Raman D and G peak position, D peak intensity, FWHM of G peak, and intensity ratio of D peak to G peak. Detailed interpretation of Raman results concluded that there was sp2 clustering occurring with temperature. There was no sp3-to-sp2 conversion after heating up to 300C -- also as confirmed by multiwavelength Raman. XPS suggested oxidation on both DLC film and seed layer at 300C. In terms of DLC film performance impact, these changes seemed to make the DLC film more opaque after heating as shown by the n and k optical values. Also more film wear was observed with heating as measured by nanoindentator.

NNF 2357, Oral, Aqueous Chemical Growth of uniform and smooth ZnO nanorod films on flexible polymers

Luo Jack;Dheeraj Singh
Inst. of REET, University of Bolton; United Kingdom

Zinc Oxide (ZnO) has excellent electronic, optoelectronic and piezoelectric properties, and has been used for fabrication various devices, and has recently been explored for flexible electronics such as solar cells, displays and other flexible devices. However, so far ZnO films for flexible electronics are all obtained by physical deposition methods such as sputtering and laser assisted deposition. These methods require expensive equipment, have deposition temperature often higher than the tolerance temperature of the flexible polymer substrates, and could only be used to deposit polycrystalline film. On the other hand, various nanostructured ZnO has demonstrated excellent properties for optoelectronic, piezoelectric applications, but unable to be deposited by most of physical deposition methods. In this paper we have reported the synthesis of homogeneous, wafer scale and densely packed ZnO nanorod films by chemical solution method on different substrates under various growth conditions. Well-aligned single crystalline (ZnO) nanorods and uniform thin films were successfully grown at low temperature on seeded flexible Kapton® polyimide films, using zinc nitrate hexahydrate and hexamethylenetetramine as precursor solution. The average diameter and length of the ZnO nanorods increase to different degree with increasing precursor concentration where as the temperature effect on the growth stabilize at 95oC and the diameter of the nanorods starts decreasing for further higher temperatures. The growth rate of ZnO thinfilms grown on the flexible polymer substrates is higher than that grown on solid substrates. The average surface roughness of these thin films is approximately 20nm. Scanning electron microscopy (SEM), atomic force microscopy, Photoluminescence (PL), X-ray diffraction (XRD) measurements were used to analyze the structural and optical properties of ZnO nanorods. The results demonstrated that this method has a great advantage of low temperature growth of high quality ZnO nanorod films, suitable for planar structure devices fabrication.

NNF 2362, Poster, Structural, optical and electrical properties of Li-doped ZnO thin films Influenced by Annealing temperature

Wang Bing;Tang Li-dan; Wang Jian-zhong
Department of Materials science and engineering, Liaoning University of technology; China

Li-doped ZnO thin films were deposited by using radio frequency magnetron sputtering and then annealed under temperature of 400~650℃ in O2 ambient. The morphology, structural and optical properties of Li-doped ZnO films were examined by FESEM, XRD and U-3400 Spectrometry. The results showed that ZnO films annealed under temperature of 500~600℃ possess a good crystalline with c-axis orientation, uniform thickness and dense surface and show a high transmittance (~85%) in the visible region. The Hall measurement demonstrated that resistivity of Li doped ZnO films decreased with annealing temperature increasing and conduction type had faint p-type conduction when annealing temperature is 550℃. A p type doping mechanism was established by calculating electronic structure and formation energies.

NNF 2364, Oral, Silicon Solar Cell with Anti-reflective Structures Fabricated Using Anodic Aluminum Oxide Method

Chen Sheng-Hui;Chen Chun-Ko; Tseng Shao-Ze; Hsu Chieh-Hsiang
Department of Optics and Photonics, National Central University; Taiwan

In recent years, the reduction of frontal reflection plays an important role in solar cells. The textured structure achieves the function of increased light-trapping by extending the length of the optical path of the incident rays in the solar cells which can increase the absorption. Researches have fabricated nano-structures on the silicon substrate to be anti-reflective structure for solar cells. However, the bonding on the silicon surface will be broken by the destructive etching to increase the surface defect. How to achieve a low reflective structure without increasing defects for the anti-reflective structure on the surface of the solar cell becomes more and more important. In our study, nano-channel arrays on the aluminum film were fabricated to achieve anti-reflective structure using anodic aluminum oxide method. The nano-channel arrays were formed as a mask for silicon substrate, and the nano-cone structure was made after the high density plasma (HDP) dry etching. The period and the depth of the nano-cone structure are both about 200 nm. The average reflectance of the nano-cone structure is 1.1% and 3.74% within 400-1000 nm at normal and 60 degree incident angles, respectively. The antireflection effect of the nano-cone structure is including the properties of broadband and wide-angle.

NNF 2368, Poster, Nanocomposites of Nickel Alloys on Alumina for the Catalytic Hydrogenation of α-Pinene

Yang Tsong-Jen;
Dept. of Materials Science and Engineering, Feng Chia University; Taiwan

Firstly Al2O3 nanoparticles (about 58 nm) were surface modified by alkaline rinsing. After adsorption of nickel ions at room temperature, and reduced by hydrogen gas at 500oC for 2 hours, nickel clusters on alumina were obtained. The coating of Ni, Ni-P(7wt.%), Ni-P(13wt.%) or Ni-B was successfully deposited on the surface of Al2O3 nanoparticles by electroless plating with Pd-free surface activation method. Particle size distribution of nanocomposites was ranged from 85 to 150 nm. The catalytic hydrogenation of α-pinene was investigated by nanocomposite catalyst of Al2O3 coated with Ni alloys at temperatures from 110 to 150℃ and hydrogen pressures from 200 to 400 psi. The hydrogenation reaction products were separated by gas chromatograph (GC) with Varian CP-Sil 5CB capillary column of diameter 0.53 mm and 50 m in length. The flame ionization detector (FID) was used for analysis. The α-pinene was reduced to trans-pinane and cis-pinane after hydrogenation and with cis-pinane as the major product. This catalytic reaction can be regarded as stereospecific for cis-addition of hydrogen. The conversions of α-pinene were nearly 100% with nanocomposite catalysts at 400 psi hydrogen pressure and 150℃ for 30 min. Characterizations of the nanocomposites microstructure were performed by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive X-ray spectrum (EDS) and electron spectroscopy for chemical analysis (ESCA). Images of Al2O3 nanoparticles, nickel clusters on alumina, and nickel coatings can be observed by TEM. Morphology and composition of nanocomposites were examined by FE-SEM with EDS. Surface elemental atomic percentages of nanocomposites were investigated by ESCA.

NNF 2383, Poster, The growth of Al doped ZnO Nanosheet arrays influenced by pulsed electromagnetic field

Wang Jian-zhong1;Tang Li-dan1; Wang Bing1; Du Hui-ling2
1Department of Materials science and engineering, Liaoning University of technology; China
2Department of Chemical and Environmental engineering, Liaoning University of technology;China

Highly-ordered ZnO nanosheet arrays had been successfully prepared by hydrothermal methods assisted with pulsed electromagnetic field (PEMF). The effects of pulsed electromagnetic field on morphology and structural properties of ZnO nanosheet arrays were studied in detail. FESEM results showed ZnO nanosheet arrays with PEMF had better orientation and higher order than that without PEMF and the thickness of ZnO nanosheet arrays with PEMF is ~5nm. The XRD analysis showed All ZnO nanosheet arrays are crystallized in the wurzite phase. The ultraviolet emission peak increased and showed a slightly red shift, while the photoelectrochemical performance was improved with PEMP. At last, a possible mechanism of pulsed electromagnetic field acted on nanosheet arrays was proposed.

NNF 2384, Poster, STRUCTERAL AND PROPERTIES OF ALUMINIUM OXIDE FILM ON Si AND Al2O3-TiC SUBSTRATES PREPARED BY RF DIODE SPUTTERING

PANITCHAKAN HATHAI;
Physics Dept.,Mongkut’s University of Technology Thonburi; Thailand

The development of eletrically insulating deposited film on magnetic head recording wafer is one of the key magnetic head recording technologies for hard disk drive data storage, such as undercoating, gap between reader and writer elements and overcoating for encapsulation of magnetic head recording. The aluminum oxide (Al2O3) material is attracting and increasing attention since it is widely used as an insulator of magnetic head recording. Therefore, the propose of this study is to deposit Al2O3 films on Si substrate and Al2O3-TiC ceramic composite substrate by RF diode sputtering with a sputtering power of 7 KW and a substrate bias voltage of 150V. The structure of Al2O3 film and surface morphology were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy and atomic force microscopy (AFM). KEYWORDS: magnetic head recording wafer, aluminum oxide (Al2O3), RF diode sputtering, Si substrate, Al2O3-TiC ceramic composited substrate

NNF 2385, Oral, Dispersion of Nanoparticles on Porous Alumina and Titania Support: Structured Nanocatalysts System Formation

Taib Mustaffa Ali Azhar1;Lockman Zainovia2; Abdul Razak Khairunisak3; Cheong Kuan Yew4
1Advanced Technology Training Centre (ADTEC) Taiping, PT 15643, Kamunting Raya, Mukim Asam Kumbang, 34600 Kamunting, Perak.; Malaysia
2School of Materials & Mineral Resources Engineering, Universiti Sains Malaysia (Engineering Campus), 14300 Nibong Tebal, Seberang Perai Selatan, Penang.;Malaysia

Alumina and titania films were made to have nanoporous structure on aluminium and titanium foil respectively by a simple anodic process. Onto these nanoporous structure, nanoparticles like iron oxides with diameter of ~ 50 nm were dispersed by spin coating in an effort to produce a so-called structured nanocatalyst system. The particles will follow the pattern of the underlying porous support forming well-structured catalysts. Such catalysts system is hypothesised to have much better catalytic properties for the formation of various chemicals. To form the porous titania, anodic process was conducted in fluoride sodium sulphate bath. At 20 V the oxide was found to have diameter of ~ 80 nm and the thickness of the oxide can reach 1000 nm depending on the pH of the electrolyte. Similarly, anodic oxidation of Al foil in a standard two electrode bath also resulted in porous nanostructure but the electrolyte content and the voltage applied was found to be different than anodic process done on titanium. X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) were used to characterize the structure and morphology of the porous oxides formed. The structured nanocatalyst system was also characterised by these standard methods as well.

NNF 2399, Oral, Influence of yttrium addition on mechanical properties and oxidation behavior of ZrN coatings

Wang Zhoucheng1;Wu Zhengtao2; Qi Zhengbing1; Liu Bin1; Zhu Fangping1
1College of Chemistry and Chemical Engineering, Xiamen University; China
2College of Materials, Xiamen University;China

ZrN hard coatings have been proven to be excellent candidates to improve wear protection, oxidation and corrosion resistance for machining tools and engineering components. Their mechanical properties and oxidation resistance can be further improved by adding reactive element yttrium. Zr-Y-N coatings with various yttrium contents (0 to 21 at. %) are fabricated by DC magnetron sputtering co-deposition. The effect of varying amounts of yttrium addition on the microstructure, mechanical properties and oxidation behavior of ZrN coatings has been studied. The results reveal that yttrium atoms substitute zirconium atoms in Zr-N lattice forming the solid solution Zr-Y-N coatings. The preferred orientation changes form (200) to (111) with yttrium addition, while the grain sizes keep approximately. The indentation hardness of ZrYN coatings first increases from 13.57 GPa to 25.99 GPa with increasing yttrium and followed by a decrease to 16.94 GPa with further increase in yttrium content. The oxidation products vary from m-ZrO2 to t- ZrO2, to c- ZrO2 with the increase contents of yttrium element.

NNF 2405, Poster, Periodic Si nanostructures fabricated by nanosphere lithography and anisotropic wet etching

LIN Y. H.1;LEE S. W.2; CHENG S. L.1
1Dept. of Chem. & Mater. Eng., National Central University; Taiwan
2Inst. of Mater. Sci. & Eng., National Central University;Taiwan

Surface-patterned Si nanostructures have attracted a lot of attention due to their unique physical and optical properties and potential applications in various fields, especially in advanced nanoelectronic and photovoltaic devices. To produce periodic nanostructure arrays on Si substrates, a variety of lithography techniques have been developed. In this study, we propose a new, facile and efficient method to fabricate size-tunable periodic Si nanostructure arrays, which is based on the plasma modified nanosphere lithography with an anisotropic wet chemical etching technique. No additional thin-film deposition equipments and metal film hard masks are needed in this process. From SEM and AFM observations, it is clearly demonstrated that large-area, well-ordered nanohole structures were successfully fabricated on the surfaces of single-crystal Si substrates after appropriated O2 plasma treatments and subsequent site-selective chemical etching. The Si nanohole arrays exhibit the same hexagonal arrangement as the initial colloidal nanospheres template. The size, shape, and spacing of Si nanoholes could be controlled by adjusting the O2 plasma treatment conditions and the wet etching duration. The experimental results present the exciting prospect that with appropriate controls, the plasma modified nanosphere lithography technique promises to offer an effective patterning method for fabrication of regular nanohole arrays on various Si-based substrates without complex lithography.

NNF 2407, Oral, Increased Light Output Intensity of GaN-Based Light-Emitting Diodes Using Accurate Dimensions of Two-Dimensional Photonic Crystal Structures with Electron-Beam Lithography

You Yao-Hong1;Su Vin-Cent1; Chen Yi-Ji1; Li Ming-Lun1; Kuan Chieh-Hsiung1; Lin Ray-Ming2; Yu Sheng-Fu2
1Graduate Institute of Electronics Engineering, National Taiwan University; Taiwan
2Graduate Institute of Electronics Engineering, Chang Gung University;Taiwan

In order to achieve two-dimensional photonic crystal (PC) structures with exact dimensions on nitride-based light emitting diodes (LED), electron-beam lithography and inductively plasma dry etching were used in the experiment. During the research, we fabricated PC air hole arrays with the periodicity of 180nm, depth of 108nm, and diameters, which were varied from 60 to 120nm. The surface morphology, periodicity, depth and diameters of accomplished PC structures were re-examined by the instrument of FEI Dual-Beam NOVA 600i Focused Ion Beam. From the analysis of our micro photoluminescence equipped with the C-Focus system which corrects for microscope focus drift, we demonstrated that the light output intensity would be enhanced due to the increase of the air hole diameter. Compared with the conventional sample without PC structures, the maximum of the enhanced relative intensity is up to 96% through the sample with 120nm-diameter PC air hole arrays.

NNF 2409, Oral, Thermal stability of nanocomposite ZrO2-Al2O3 coatings deposited by reactive pulsed-DC magnetron sputtering

Zukerman Ido;
Division of Chemistry, NRC-Negev; Israel

Ternary zirconia-alumina coatings with different compositional ratios, ranging from pure zirconia to pure alumina, were deposited by co-sputtering from Zr and Al targets in argon-oxygen mixtures. The composition was controlled by the Zr/Al target power ratio provided by two synchronized pulsed-DC power supplies. The coatings were ~1µm thick and they were deposited on floating substrates at a temperature of 650±3K. XRD indicated that the pure zirconia coatings had a monoclinic structure with a grain size of 15 nm, while the pure alumina coating was amorphous. Adding up to 19 at.% of alumina to a zirconia coating stabilized the cubic zirconia phase with a grain size of 10-12 nm, while the alumina remained amorphous. The hardness of the nanocomposite structure increased from 12±1 GPa to 16±1 GPa for 17-19 at.% alumina content. At higher alumina content, the zirconia phase became amorphous and the hardness decreased to 10-11 GPa. The internal stress of pure zirconia was compressive (-60 MPa), while the internal stress was tensile (+260 MPa) for an alumina content of 29 at.%. At higher alumina concentration, the tensile stress decreased, and it reached a maximum compressive value of -150 MPa for the pure alumina phase. The thermal stability of the zirconia-alumina coatings was studied by measuring the phase composition, hardness and high temperature stress at temperatures up to 1173K. The stress analysis revealed that the structure changed at temperatures of 700-750K. Annealing of the pure alumina or zirconia coatings at a temperature of 973K increased the hardness to maximum values of 20±1 GPa, however, at a higher annealing temperature of 1173K, annealing reduced the hardness to 12±1 GPa. The hardness of the nanocomposite zirconia-alumina coatings increased from 16±1 to 18±1 GPa with annealing at 1173K, and the high hardness remained after annealing. From the analyses of stress at high temperatures, phase stability and hardness before and after annealing, we concluded that adding alumina to the zirconia phase promotes the formation of nanocomposite zirconia-alumina coatings with higher thermal stability compared to single-phase alumina or zirconia.

NNF 2414, Oral, Structural and Optical properties of nano-TiO2 thin films fabricated from low grade mineral precursors

Mahmoud Mahdi1;Sahdan Mohd. Zainizan2; Abd. Shukor Mohd. Hamdi3; Nayan Nafarizal2
1Advance Manufacturing and Material Processing Center, Universiti Malaya; Malaysia
2Microelectronics and Nanotechnology-Shamsuddin Research Center, Faculty of Electrical and Electronics Engineering, Universiti Tun Hussein Onn Malaysia;Malaysia
3Department of Engineering Design and Manufacture, Faculty of Engineering, Universiti Malaya;Malaysia

Nano-TiO2 particles processed from ilmenite-derived synthetic rutile were used as a precursor to produce nano-TiO2 thin films. The films were produced by the solgel method, and deposited onto a glass/ITO substrate via the spin coating technique. The structural and optical properties of the films are then studied using the XRD, AFM, FESEM/EDX and the UV-Vis-NIR techniques. The XRD revealed that the thin films were in the anatase phase, and are for the most part, crystalline. The thickness of the deposited films is in the range of 100 nm, and its surfaces were rough, although it was uniform. FESEM/EDAX inspection revealed that thin films were made up of aligned particles, with the sizes of each particle being quite similar. Similarly, EDX proved that the thin films were 100% TiO2. UV-Vis-NIR analyses reveal the optical bandgap to be in the range of 3.2-3.7 eV, with the optical transmission in the range of 80-100%, depending on the sample. It is concluded that synthetic rutile derived ilmenite is capable of producing high quality nano-TiO2 thin films that may be viable for a multitude of novel applications.

NNF 2415, Oral, Fabrication of micro/nano thin film membrane

HUANG Zhaohong1;WARKIANI Majid Ebrahimi2; NGUYEN Thanh Truc1
1Surface Technology Group, Singapore Institute of Manufacturing Technology; Singapore
2School of Mechanical & Aerospace Engineering, Nanyang Technological University;Singapore

Micro-fabricated sieves/membranes that contain pores with the same size and shape can overcome the micro-structural defects of the traditional membranes. The fabrication process allows enough flexibility to control the porosity and the pore size and shape according to desire application for separation of e.g. bacteria from water in order to have higher flow rate, lower clogging ratio, better recovery and enough reliability. Among them, ceramic and metallic thin film membranes are superior to others due to its better mechanical, thermal and chemical stabilities. However, if the desired pore size of the thin film membranes is reduced down to submicron levels, the existing microfabrication processes face troubles in consideration of either technical readiness or cost effectiveness. The presentation will focus on the current status, our recent achievements, and perspectives.

NNF 2419, Poster, Formation mechanism of sputter deposited self-assembled alternating layered metal containing hydrogenated amorphous carbon film

Ting Jyh-Ming1;Wu Wan-Yu2; Chang Chi-Lung2
1Department of Materials Science and Engineering, National Cheng Kung University; Taiwan
2Department of Materials Science and Engineering, MingDao University;Taiwan

Self-assembled multilayer structures have been recently observed. Such self-assembled structures occur not in only metal-carbon systems but also ceramic-carbon, alloys, and metal-ceramic systems. In the carbon-metal systems, different groups have investigated a-C:Cu, a-C:Au, a-C:Ag, a-C:Fe a-C:H/Ti, a-C:H/W, a-C:H/Mo, and a-C:Cr thin films using different deposition techniques. Regardless of the differences in the metal type and the deposition technique used in these groups, it appears that not all the deposition conditions, including the metal type, lead to the formation of such interesting microstructures. It is also noted that although the self-assembled layered structures were found in different processes with different materials, and explained by different models, effects of the growth parameters and the growth mechanism have not been fully understood. In this research, we have used a reactive magnetron sputter deposition technique for the preparation of a-C:H/Me thin films under various deposition conditions. As for the types of metals investigated, the research has covered a wider range of metals, including Al, Si, Fe, Ni, Cu, and Pt, than that of the other groups. Various types of metal containing amorphous hydrogenated carbon thin films (a-C:H/Me) have been grown on different substrates using one single target, a rotating but not revolving substrate, and constant feed gas compositions in a conventional reactive sputter deposition chamber. Meanwhile, the growth and characteristics of metal containing amorphous hydrogenated carbon thin films (a-C:H/Me) were studied. In order to explain the formation of the distinct structures, correlations were first made among the deposition rate, the composition, the crystallinity, the surface chemistry, and the microstructure of a-C:H/Me thin films. A growth mechanism based on the considerations of clustering of carbon and metal, segregation of carbon, catalytic effects of metal, formation of carbide, energy of adatoms, and surface diffusion of metal and carbon, has been developed.

NNF 2422, Poster, Surface modification and percolation study of vapor growth carbon nanofiber for use in polymeric composites

Hsu Cheng-Hao;Wu Wan-Yu
Department of Materials Science and Engineering, MingDao University; Taiwan

Vapor growth carbon nanofibers (VGCNFs) exhibit unique physical and chemical properties as compared to other traditional carbon fibers, especially in electrical and thermal performance. VGCNF not only represents an excellent reinforcing material but also provides low cost benefit. Both structural and functional composites reinforced by VGCNFs have therefore received tremendous attentions. For use in composite materials, the surface of VGCNF is required to have proper functional groups and the percolation limit must be identified. In this study, VGCNFs synthesized using a continuous process was surface modified using post-synthesized chemical and physical treatments. The surface chemistry of modified VGCNFs was using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Surface modified VGCNFs were then mixed with a two-part epoxy resin for the fabrication of composites. The electrical conductivity of the resulting composites was measured using a 4-point probe method. Based on the electrical conductivity measurements, the percolation limit was determined. The fiber distribution and fiber/matrix interface in the composites were also examined using high-resolution scanning electron microscopy.

NNF 2431, Oral, Oxygen segregation at the grain boundaries in nanocrystalline Al thin films

Samudrala Saritha1;Malone Patrick2; He Mo-Rigen2; Moody Michael1; Gianola Dan2; Cariney Julie1
1Australian Centre for Microscopy and Microanalysis, University of Sydney; Australia
2Materials Science and Engineering, University of Pennsylvania;USA

Nanocrystalline (nc) metallic thin films have potential as high-performance structural and functional materials, but due to their very small grain sizes, grain size stability is a major issue in these materials leading to the degradation of properties over time. In these films, grain boundaries (GBs) can be responsible for plastic deformation by their multi directional response to applied stress. In our previous study on nc-Al it was reported that the presence of impurities / solutes in the vicinity of the GBs has dramatic effect on strength and ductility of these films, by modifying the deformation behaviour. [1, 2] Here we investigate three types of nc-Al thin films deposited by DC magnetron sputtering. High purity Al2O3 was used to introduce differing amounts of pure oxygen into the Al films, with different sputtering conditions used for varying oxygen content. The results revealed a relationship between oxygen content and the grain size. To overcome the inherent challenges that arise in the microstructural analysis of the grain boundaries using transmission electron microscopy (TEM) (overlapping of grains for GB observation and limited resolution for chemical analysis of impurities/solutes) atom probe tomography (APT) was employed. APT reveals information about interfacial segregation in three dimensions and, by using computational methods, the excess of solute/impurity atoms can be quantified per unit area of GB. The APT measurements to be presented reveal whether segregation of oxygen atoms occurs at the GBs. A direct relationship between oxygen content and grain size stability in the as deposited films has been established, e.g. films with higher oxygen content were shown to have smaller average grain size. We will also present the relationship between the grain size, the oxygen segregation and the mechanical properties of these thin films. Finally the initial results of in-situ TEM tensile testing of nc-Al films (carried out using a Hysitron Push-to-Pull testing device) will be included in order to correlate the deformation mechanisms to the measured mechanical properties. References: [1] D.S. Gianola, B.G. Mendis, X.M. Cheng, K.J. Hemker, Materials Science and Engineering A 483–484 2008: 637–640 [2] F. Tang, D.S. Gianola, M.P. Moody, K.J. Hemker, J.M. Cairney, Acta Materialia 60 (3) 2012: 1038-1047

NNF 2436, Oral, Micropatterning of Metal Oxide Thin Films using Self-assembled Monolayers

Masuda Yoshitake;
National Institute of Advanced Industrial Science and Technology (AIST); Japan

Site-selective deposition of metal oxide was realized on self-assembled monolayers(SAMs) in aqueous solutions. Molecular recognition of SAMs was effectively used to accelerate or suppress growth of metal oxide. These processes can be used for the fabrication of various ceramic devices under environment-friendly conditions.

NNF 2438, Poster, Magnetic exchange coupling studies on Ni/NiO core-shell nanoparticles

Jhong-Yi Ji;Sheng Yun Wu
Department of Physics, National Dong Hwa University; Taiwan

In this work, we succeeded in preparing Ni/NiO core-shell nanoparticles using the thermal evaporation method. The magnetic properties of Ni/NiO core-shell nanoparticles can be treated as a ferromagnetic-Ni-core and antiferromagnetic-NiO-shell compound coupled by an exchange interface coupling between them. Controlling the size of Ni-core within a constant NiO shell (~ 2 nm) can tune the competition between the surface magnetic anisotropy and exchange interface coupling. The evolution of core-shell magnetization triggered by cooling applied magnetic field at 1.8 K was observed and well described by a core-shell anisotropic energy model that can be applied to accurately simulate the hysteretic loops in the Ni/NiO core-shell nanoparticles.

NNF 2447, Poster, The characteristics of corrosion production films formed on A350LF2 steel in wet hydrogen sulfur environments

ZHENG Shuqi1;WANG Danni1; QI Yameng2; CHEN Changfeng1; CHEN Liqiang1
1Department of Materials Science and Engineering, China University of Petroleum, Beijing; China
2School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics;China

The morphologies and compositions of corrosion production films formed on A350LF2 steel after exposure to H2S environments were investigated by the scanning electron microscope and X-ray diffraction analysis. The results showed that the morphologies, compositions and compact density of corrosion production films changed with the increasing of H2S pressure and the prolonging of immersion time. The corrosion production was composed of mackinawite and cubic FeS in the low H2S pressure environment, which were not beneficial to the corrosion resistance of A350LF2. However, when the H2S partial pressure increased to 1.6MPa, the crystal structure of corrosion production film transformed to troilite FeS. In addition, the crystal size and the compact density of corrosion scales increased with the prolonging of immersion time.

NNF 2449, Oral, Formation of the nano-structure in the surface layer of LY12 Al-alloy during burnishing process

Han Zhi-yuan;Luo Hong-yun; Zou Jian
Materials Science and Engineering Dept., BeihangUniversity; China

The nano-structure development in the surface layer of LY12 Aluminum alloy during burnishing process was investigated in this study. The results indicate that the burnishing processing can both refine the grains to an average size of 40nm, and introduce an intense texture in surface layer of 50μm thick. The transmission electron microscope (TEM) and electron back-scattering diffraction (EBSD) studies of the different depth layers from top surface show that the burnishing processing can induce severe plastic deformation of materials in near surface layer, and produce sub-structures, e.g. dislocation walls, dislocation tangles. The interaction between dislocations and second phase particles can also provide the sub-boundaries for the formation of nano-grains. With the increasing strain, the orientations of the neighboring macro-grains become less misoriented, thus an enhanced brass texture is observed in near surface layer. Meanwhile, the subdivision and rotation of the sub-structures and sub-boundaries realize the nano-crystallization in surface layer. The nano-grains in surface layer mainly concentrate at the prior grain boundaries between neighboring grains with the same orientations. The formation mechanism of the coexisting of nano-crystalline and texture characters in the burnishing surface layer are also discussed in the present study.

NNF 2450, Poster, Study on the biocompatibility of BMP-2 plasmid DNA loaded chitosan film in vitro and in vivo for bone substitutes

Li Juan;Lin Jun; Lu Yan; Tu Chengwei
Department of Stomatology,First Affiliated Hospital,Faculty of Dentistry,ZhejiangUniversity; China

Bone morphogenetic proteins (BMPs), especially BMP-2, play crucial role in bone regeneration. However, to sustain releasing of BMP-2, Chitosan film is possible approach to be delivery carrier of BMP-2 plasmid DNA, due to the cationic charge, biodegradability and biocompatibility. To investigate the effect of chitosan film as a carrier of BMP-2 plasmid DNA for bone regeneration, complex was prepared. SEM and MTT were examined for osteogenic adhesion and proliferation of MG63 cell at different time points in vitro. The bone formation ability of BMP-2 plasmid DNA loaded chitosan film in vivo was observed by X-ray observation and histological analysis at 4, 8 and 12 weeks after operating the defects of rat calvarium (5 mm diameter). The results revealed that the cells were attached on the 10ug BMP-2 plasmid DNA chitosan film and exhibited excellent morphology. Number of cells on the complex film grew less than that of other groups in 24 hours (p<0.05), however, there was showed no difference compared with other groups in 96 hours (p>0.05). Besides, 10ug BMP-2 plasmid DNA chitosan film possess the better ability of bone formation in vivo, due to the new bone formed more than other groups in 8 weeks. These results demonstrated that chitosan film appeared to be a safe and effective carrier of BMP-2 plasmid DNA. The combination of BMP-2 plasmid DNA loaded chitosan film was suggested a good cellular compatibility in vitro and promoted bone formation in vivo.

NNF 2470, Oral, Characterizations of nanostructured thin film composed of phosphorus-doped Si nanocrystals embedded in silicon nitride matrix

Wu Ping-Jung;Chen I-Chen
Institute of Materials Science and Engineering, National Central University; Taiwan

For development of next generation crystalline Si solar cells, one of the new concepts for heterojunction solar cells is using wide bandgap materials as emitter layers due to the higher light transmittance. Silicon nanocrystals (Si-NCs) embedded in a wideband gap dielectric matrix, such as a-SiCx, a-SiOx, a-SiNx could be used for this purpose. Moreover, for increasing the conductivity of Si-NCs, incorporating the dopants into Si-NCs has also been demonstrated. So far, the doped Si-NCs in a-SiCx or a-SiOx matrix have been used for device fabrication. Theoretically, a-SiNx has a higher bandgap than a-SiCx and better conductivity than a-SiOx. However, there are few studies for discovering the properties of the doped Si-NCs embedded in SiNx. In this study, we first utilized electron cyclotron resonance chemical vapor deposition (ECRCVD) rather than sputtering or inhomogeneous implantation process to grow homogeneous Si-rich SiNx films doped with phosphorus atoms on quartz substrates. The initial doping concentration was controlled by changing the introduced PH3/SiH4 gas flow ratio. The as-grown phosphorus doped Si-rich SiNx thin films were then annealed under nitrogen ambient at 950 °C for the formation of phosphorus doped Si-NCs. The micro-Raman spectroscopy and transmission electron microscopy (TEM) were used to investigate the phase separation behavior after high temperature annealing. The optical and electrical characterizations were carried out using the UV-Vis spectroscope and the transmission line method, respectively.

NNF 2475, Poster, The Fabrication for the Silicon nanowire/pyramid arrays based solar cells

Huang Bohr-Ran;Hsu Chun-Hao; Yang Ying-Kan
Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology; Taiwan

A simple process for the silicon based solar cells is developed by using the silicon nanowire/pyramid arrays. Pyramid arrays are first textured with alkaline solution and then the silicon nanowire/pyramid arrays are formed by the metal-assisted wet electroless etching technique (with 1, 2, 3, 4 and 5 min). A PSG doping process is adapted using a sol-gel method with phosphorus pentoxide (P2O5) powder combined with a screen-printing technique for the fabrication of electrodes. No antireflection layer coating is used in this process. SEM and UV-VIS spectroscopy are used for the analyses of surface morphology and optical properties. The silicon nanowire/pyramid arrays solar cells are evaluated by the current–voltage measurements under the standard test condition (STC). It is found that the average reflectivity decreases for all the nanowire/pyramid arrays based solar cells (11.3, 6.26, 4.32, 4.18, and 3.4%) compared to the pyramid arrays based solar cell (14.91%). It is noted that certain length (~272 nm) of silicon naowires possesses better solar cell performance (9.57%). It is indicated that better antireflection properties and better metal contacts are for the nanowire/pyramid arrays based solar cells. The nanowire/pyramid arrays show potential for low cost and mass-production in commercial solar cells applications.

NNF 2478, Oral, Thermodynamic Study of Ethanol Effects on Gold Nanoparticle Assembly at Water/Oil Interface

WANG Puqun1;ZHAO Qin2; WONG Chee Cheong3
1School of Materials Science and Engineering, Nanyang Technological University; Singapore
2School of Materials Science and Engineering, Nanyang Technological University;Singapore
3School of Materials Science and Engineering, Nanyang Technological University;Singapore

This project has investigated the effects of ethanol in promoting the formation of Gold nanoparticle (Au NP) monolayer at water/oil interface. The assembly behaviour of Au NPs at the interface was studied by a contact angle model and a thermodynamic analysis. An optimized ethanol dose was found when the interface contact angle approached 90o. At this optimized ethanol dose, it would be favourable to form close packed monolayers due to the destabilization effect of ethanol which enhanced Au NPs adsorption. Further discussion on the Gibbs free energy of the system proposed a theoretical explanation on the adsorption mechanism from a thermodynamic point of view.

NNF 2483, Oral, Study of Ionic Strength Effects on Gold Nanoparticle Assembly at Air/Liquid Interface

ZHAO Qin1;WANG Puqun2; WONG Chee Cheong3
1School of Materials Science and Engineering, Nanyang Technological University; Singapore
2School of Materials Science and Engineering, Nanyang Technological University;Singapore
3School of Materials Science and Engineering, Nanyang Technological University;Singapore

This project has investigated the effects of ionic strength within the subphase region on electrostatic templated self assembly of negatively charged gold (Au) nanoparticles at air/liquid interface. Langmuir-Blodgett technique was applied to assemble Au nanoparticles at the interface templated by a monolayer of cationic surfactant octadecylamine (ODA) molecules. The ionic strength of the subphase was manipulated by adjusting the ionic contents through addition of cationic surfactant, addition of anionic surfactant, or removal of residual ions in the Au hydrosol. It was found that addition of cationic or anionic surfactant would reduce the attractive interaction between Au nanoparticles and the templating ODA monolayer, which reduces the Au nanoparticle adsorption at the interface. Removal of remaining ions would enhance the attractive interaction, which resulted in extensive adsorption and aggregation of nanoparticles at the interface. By adjusting the ionic content after removal of the residual ions, a close packed monolayer of Au nanoparticles was formed at the interface.

NNF 2486, Poster, The Effect of ZrN Antidiffusion Layer on the Electrical and Physical Properties of Metal-Gate/ZrN/Zr-Doped Dy2O3/Si MIS Nanolaminated Structures

Chang Hsu-Sheng1;Juan Pi-Chun1; Ou Tao-Ke1; Huang Jen-Hung1; Mong Fan-Chen1; Wang Jyh-Liang2; Hsieh Tsang-Yen2
1Department of Materials Engineering and Center for Thin Film Technologies and Applications, Ming Chi University of Technology, New Taipei 243; Taiwan
2Department of Electronics Engineering, Ming Chi University of Technology, New Taipei 243;Taiwan

High-k dielectric is a poor barrier to oxygen diffusion, which causes the uncontrolled growth of a low-interfacial layer between high-k and Si during high-temperature annealing. Several approaches including surface nitridation, HfOxNy and HfN/HfO2 gate stacks with a HfN capping layer have been suggested to improve the thermal stability, EOT, work function, and leakage current. In contrast, there are no reports using ZrN as the capping layer for ZrO2 and Zr-based dielectrics. Based on the simulation results, the hardness and stress release of ZrN with adjacent high-k materials are lower and better than TiN, respectively. Additionally, the resistivity and formation energy of ZrN are the lowest as compared to TiN and HfN. Therefore, it is worth to study the ZrN as the capping layer for Zr-based dielectrics. In this work, two structures with ZrN capping layer of Ti/ZrN(1.5 nm)/Dy2O3:Zr(3.5 nm)/Dy2O3(3.5 nm)/Si, Ti/ZrN(1.5 nm)/Dy2O3(3.5 nm)/Dy2O3:Zr(3.5 nm)/Si, and two structures without ZrN capping layer Ti/Dy2O3:Zr(3.5 nm)/Dy2O3(3.5 nm)/Si, Ti/Dy2O3(3.5 nm)/Dy2O3:Zr(3.5 nm)/Si were fabricated. The electrical properties such as the leakage current, capacitance, and flatband voltage shift were compared in the postannealing temperature range of 550 to 850℃. The flatband voltage shift decreases with increasing the postannealing temperature, which indicates the reduction in oxide trap charges especially for the MIS structures with ZrN cap. The dielectric constant is also enhanced due to lesser outdiffusion of Ti, O and Dy atoms from ZrN layer. The chemical bonding and atomic percentage were studied by the depth profile of x-ray photoelectron spectra (XPS). The x-ray reflection (XRR) measurements were also studied for the ultra-thickness change in nanolaminated structures.

NNF 2489, Oral, Study of the Formation of Hybrid Particle Film under Electric Field and the Subsequent Porous Film Formation by Chemical Treatment

LIU YAYUAN1;NG ERIC CHIN HONG2
1School of Materials Science and Engineering, Nanyang Technological University; Singapore
2Singapore-MIT Alliance, Nanyang Technological University;Singapore

Study of the Formation of Hybrid Particle Film under Electric Field and the Subsequent Porous Film Formation by Chemical Treatment Yayuan LIU1#+, Eric Chin Hong NG2, Chee Cheong WONG1 1School of Materials Science & Engineering, Nanyang Technological University, Singapore 2Singapore-MIT Alliance, Nanyang Technological University #Corresponding author: yliu11@e.ntu.edu.sg +Presenter Colloidal particles can be drawn to stagnation points on electrodes by means of AC electrohydrodynamic and electrostatic interactions. At sufficiently high particle concentrations, resulting interactions between particles lead to assembly of particle monolayer. We aim to discuss the interactions between particles of different dielectric constants under AC electric field and how these particles interact to form hybrid particle film, offering a potential to obtain a controlled porous structure by subsequent post-etching of one type of particles. We will also briefly discuss the influence of various electric field parameters (magnitude, frequency, wave shape) on film structures.

NNF 2491, Poster, Structure and Properties of Cr-Zr-N Thin Films Prepared by Unheated and Unbiased Co-sputtering Deposition

Chantharangsi Chirawat1;Denchitcharoen Somyod1; Chaiyakun Surasing; Limsuwan Pichet
1Department of Physics, Faculty of Science, King Mongkut’s University of Technology Thonburi; Thailand

Chromium zirconium nitride (Cr-Zr-N) is an attracting and promising ternary nitride coating for many applications because of the excellent mechanical and tribological properties. The preparation of Cr-Zr-N thin film for using as a protective layer on materials that can withstand relatively low deposition temperature was studied in this work. The films were prepared on unheated and unbiased substrates by reactive co-sputtering of Cr and Zr metals. Influence of Zr discharge current and N2 flow rate on structure and properties of these films were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and nanoindentation. The results suggested that microstructure and morphology of films could develop from porous and open grain boundaries to densely packed fibrous grain by increasing of energy of Zr sputtered atoms and Zr content despite no heating and voltage biasing treatment. Energy of Zr sputtered atoms increasing with discharge current (0.2 – 0.8 A) enhanced adatom mobility whereas Zr atoms added into the films could lead to grain refinement. These films formed a nanocomposite structure that consisted of nanocrystal of (Cr, Zr)N solid solution embedded in an amorphous matrix. Substitution by Zr atoms of Cr atoms in CrN lattice structure resulted in lattice distortion and led to film hardening (14 – 20 GPa). Variation of N2 flow rate (5.0 – 8.0 sccm) affected the film adhesion. The low N2 flow rate (5.0 sccm) could give a film with larger area of Cr-Zr amorphous region that could expand more during deposition resulting in a film with highly compressive stress.

NNF 2493, Poster, Properties of Magnetron-Sputtered Silicon Nitride as Moisture Barrier Film on Transparent Polyimide/Graphene Nanocomposite

Tseng I-Hsiang1;
1Department of Chemical and Materials Engineering, National Chin-Yi University of Technology; Taiwan CHANG

Colorless polyimides (PIs) have been considered as potential substrates for flexible displays due to their excellent transparency, thermal stability, mechanical strength and flexibility. However, high water vapor or oxygen transmission rate (WVTR or OTR) of PI films limits the lifetime of electronic devices with PI films as substrates. In this study, a nearly colorless PI solution was synthesized from an alicyclic dianhydride (BCDA) and aromatic diamine (ODA) in cosolvent via one-step process. Graphene oxide (GO) synthesized by modified Hummer’s method and thermally reduced graphene oxide (RG) were mixed with the above PI solution to fabricate PI/GO or PI/RG nanocomposite films. In order to maintain high optical transparency, the nanofiller content was only 0.001 wt%. In addition to excellent optical clarity, enhanced dimensional stability (i.e. lower coefficient of thermal expansion, CTE) and mechanical strength were observed in the prepared flexible PI/GO-0.001 and PI/RG-0.001 nanocomposite films. Compared with the WVTR of 181 g-mil/m2-day for pure PI, a dramatic decrease in WVTR was observed in PI nanocomposite containing only tiny amount (0.001 wt%) of RG or GO. The WVTR of PI nanocomposites reduced to 32 and 13 g-mil/m2-day for PI/GO-0.001 and PI/RG-0.001, respectively. RG showed superior moisture barrier property than GO did. The contact angle results also indicated a more hydrophobic surface of PI/RG-0.001 than PI/GO-0.001. In order to further reduce the moisture permeation in PI films, the surface of pure PI, PI/GO-0.001 and PI/RG-0.001 was deposited with silicon nitride by a magnetron sputtering system. A significant reduction in WVTR was observed for PI nanocomposite films with a deposition thickness of 50 nm. The thickness, morphology and composition of deposited inorganic film are under investigation and are correlated to the optical and water barrier properties of PI nanocomposite films.

NNF 2499, Poster, Influence of chromium sputtering current and deposition time on structure and morphology of Ti1-xCrxN thin films deposited by magnetron co-sputtering

Paksunchai Chutima1;Denchitcharoen Somyod1; Chaiyakun Surasing; Limsuwan Pichet
1Department of Physics, Faculty of Science, King Mongkut’s University of Technology Thonburi; Thailand

Nanostructured Ti1-xCrxN thin films were grown on Si (100) wafers in a mixture of Ar and N2 plasma by reactive unbalanced magnetron co-sputtering technique without external heating and biasing substrates. The pure titanium and chromium were used as targets. The effects of Cr sputtering current (ICr) and deposition time (t) on the structure and morphology of the Ti1-xCrxN thin films have been studied. The chemical composition of the films was analyzed by energy dispersive x-ray spectroscopy (EDS). The structure of the films was investigated by x-ray diffraction (XRD) and transmission electron microscopy (TEM). Furthermore, surface and cross-sectional morphologies of the films were examined by atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM), respectively. The results showed that all of the Ti1-xCrxN films formed solid solutions with the fcc phase and were also exhibited a nanostructure with an average grain size of less than 14 nm. The Cr content in the films was calculated in the range from 23.29 to 45.37 at. %. The root mean square roughness and thickness of the films tended to increase as the Cr sputtering current and deposition time increased. The cross-sectional morphology of the films showed columnar structure. As the deposition time increases, the columnar structure of the films changes from Z1 to Z2 in accordance with Thornton’s structure zone model (SZM).

NNF 2505, Poster, Low temperature nanocomposite alignment films for optically compensated bend liquid crystal displays

Wu G. M.;
Institute of Electro-Optical Engineering, Chang Gung University; Taiwan

Low temperature processes have been highly desired for the successful development of flexible displays. However, traditional polyimide (PI) alignment films require high-temperature hard baking for at least 1 hour to complete the cyclization polymerization. It is thus difficult to design liquid crystal displays with flexible substrates. In this study, we proposed to use UV-curable liquid crystal polyimide (LCPI) in conjunction with POSS nano-particles (2-5 nm) to develop the low temperature alignment technology with wide range of liquid crystal pre-tilt angles. The photo-polymerization process was fast, and the polymer rubbing particle issues could be avoided. The results showed that, if 0.05 wt% POSS nano-particle was added in the 28-nm LCPI nanocomposite, the pre-tilt angle would be 42° for the optically compensated bend (OCB) liquid crystal displays. The cell gap was 4 μm. The POSS nano-particles provided a homeotropic alignment force, while the LCPI would give homogeneous alignment force in the horizontal direction. The force balance would have resulted different pre-tilt angles, according to the nano-particle compositions. On the other hand, the OCB cells would exhibit reduced warm-up time for fast-response liquid crystal displays.

NNF 2506, Oral, Morphological evolution of graphene and its application in transparent conducting film

Huang Po-Wei;Mishra Dillip; Ting Jyh-Ming
Department of Materials Science and Engineering, National Cheng Kung University; Taiwan

An atmospheric pressure chemical vapor deposition (APCVD) method has been used to growth graphene on 2x2 cm copper substrates. Various APCVD parameters, including gas composition, growth time, and post-growth hydrogen treatment time were examined. In particular, the growth time was carefully controlled in order to examine the morphological evolution of the obtained graphene using transmission electron microscopy. The graphene deposited on Cu substrate was then transferred onto other substrates, including (Poly(ethylene 2,6-naphthalate)(PEN), poly(ethylene terephthalate)(PET), glass, and Indium Tin Oxide(ITO) glass, using a wet transfer technique. The transferred graphere were then examined for the sheet resistance , optical transmittance, microstructure using four-point probe and UV/VIS/NIR spectrometry, and transmission electron microscopy (TEM), respectively. The morphological evolution was also investigated using TEM. Effects of the synthesis parameters on the characteristics and morphological evolution are discussed.

NNF 2507, Poster, XPS and TEM studies on internally oxidized Nb–Ru coatings

CHEN Yung-I1;CHEN Sin-Min1; Chang Li-Chun2
1Institute of Materials Engineering, National Taiwan Ocean University; Taiwan
2Department of Materials Engineering, Ming Chi University of Technology;Taiwan

The internal oxidation phenomenon of Nb–Ru coatings with a cyclically gradient chemical concentration distribution along the growth direction has been investigated after annealing under a 1% O2-Ar atmosphere at 600 oC. X-ray photoelectron spectroscopy and transmission electron microscopy were used to analyze the oxidation behavior of Nb–Ru coatings. The results revealed that Nb oxidized preferentially in the Nb–Ru coating, and partial Nb atoms oxidized to Nb5+ and Nb2+, but Ru remianed in the metallic state. The microstructure after annealing evolved to a laminated structure consisted of alternative crystalline Nb2O5 and Ru layers.

NNF 2510, Oral, Oxidation of Cr2N and CrN films: Phase transformation and oxidation mechanism

Qi Zhengbing1;Wu Zhengtao2; Liu Bin1; Zhu Fangping1; Wang Zhoucheng1
1College of Chemistry and Chemical Engineering, Xiamen University, Xiamen; China
2College of Materials, Xiamen University;China

In this study, CrNx films were deposited using reactive magnetron sputtering in argon and nitrogen atmosphere. From X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman studies, it was found that the films evolved from Cr-Cr2N → Cr2N+CrN → CrN with increasing nitrogen to total pressure ratio from 0 to 80%. A comparative study of the oxidation behavior of CrN and Cr2N films were performed. During oxidation process, phase transformation between CrN, Cr2N and α-Cr2O3 were characterized by high temperature X-ray diffraction (HT-XRD) up to 900℃ in air. The results showed that the onset oxidation temperature of CrN was 800℃ higher than that of Cr2N films 700 ℃. As the oxidation temperature is over 800℃, the Cr2N films transformed to CrN films. During the oxidation of Cr2N films, nitrogen released and α-Cr2O3 formed on the surface of the films which acted as a diffusion barrier for nitrogen. Furthermore based on the Gibbs energy calculation, the CrN films were more stable compared with Cr2N films. Hence, the transformation from Cr2N films to CrN films was favored. From the kinetic study, the oxide layer thickness against oxidation times of both CrN and Cr2N films followed a parabolic relation, which implied that diffusion of species was the rate-limited step. Marker experiment with a 5 nm thickness Au films confirmed that both inward-diffusion of O2- and out-diffusion of Cr3+ were transported modes in the oxidation.

NNF 2512, Poster, Effects of the ZnS shell layer on electrical stabilities of nonvolatile memory devices fabricated utilizing CuInS2-ZnS core-shell nanoparticles embedded in a poly(methylmethacrylate) layer

Yun Dong Yeol1;Kim Tae Whan1; Kim Sang Wook2
1Division of Nanoscale Semiconductor Engineering, Hanyang University; Korea (south)
2Department of Molecular Science & Technology, Ajou University;Korea (south)

Nonvolaitle memory devices fabricated utilizing organic/inorganic hybrid nanocomposites containing nanoparticles have emerged as excellent candidates due to interest in their potential applications with superior advantages of low-power consumption, high-mechanical flexibility, and low cost [1]. Even though some studies on nonvolatile memory devices with core-shell nanoparticles embedded in a polymer layer have been performed, very few studies concering the effect of the ZnS shell layer on electrical stability of organic bistable memory devices (OBDs) fabricated utilizing eco-friendly core-shell CuInS2-ZnS (CIS-ZnS) nanoparticles embedded in a poly(methylmethacrylate) (PMMA) layer have been carried out. This paper presents data for the variation in the electrical stabilities due to a ZnS shell in OBDs fabricated utilizing core-shell CIS-ZnS or CIS nanoparticles embedded in a PMMA polymer layer on the indium-tin-oxide (ITO) coated on glass substrates by using a simple method. The current-voltage (I-V) curves for the Al/CIS-ZnS or CIS nanoparticles embedded in PMMA layer/ITO/glass device clearly showed current hysteresis behaviors with high conductivity (ON state) and low conductivity (OFF state), indicative of an essential feature for a bistable device. The ON/OFF current ratio for the device with CIS-ZnS nanoparticles was larger than that of the device with CIS NPs. The retention characteristics of the devices with CIS-ZnS nanoparticles were more stable than that without a ZnS shell. Acknowledgment This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2010-0018877). Reference [1] D. I. Son, D. H. Park, J. B. Kim, J. W. Choi, T. W. Kim, B. Angadi, Y. J. Yi, and W. K. Choi. J. Phys. Chem. C, 115 (2011) 2341

NNF 2521, Poster, Nanocomposites of polymer and inorganic nanoparticles for optical thin films applications

Yu Yang-Yen1;Chien Wen-Chen2; Chen Po-Kan2; Chen Yung- Chih1
1Department of Materials Engineering, Ming Chi University of Technology; Taiwan
2Department of Chemical Engineering, Ming Chi University of Technology;Taiwan

In this study, the poly(acrylic)/TiO2 nanoparticle hybrid thin films were successfully synthesized by microwave-assisted polymerization method. The coupling agent MSMA was first hydrolyzed with colloidal TiO2 nanoparticles, and then polymerized with acrylic monomer and initiator to form a precursor solution. The results show that the spin-coated hybrid films have the relatively good surface planarity, high thermal stability, tunable refractive index (1.525 < n < 1.893), and excellent optical transparency in the visible range. A three-layer anti-reflection coating based on the prepared hybrid films is designed and possesses a reflectance of less than 0.5% in the visible range. Our study demonstrates a new route for preparing high refractive index poly(acrylic)/ TiO2 nanoparticle hybrid thin films for potential optical applications.

NNF 2524, Poster, Structure of L10 ordered FeNi thin film with a Cu buffer layer

Wang Dongling;Du Zhaofu; Li Bo
Department of Functional Materials, Central of Iron and Steel Institute; China

The L10 ordered alloy without a noble metal, FeNi thin film, was fabricated by using an alternate monatomic layer deposition on a Cu buffer layer. The thickness of Cu buffer layer varied from the 10 nm to 60 nm at different deposition temperature from the room temperature to 400oC. The degree of long-rang order S of FeNi film was estimated by X-ray diffraction. With the increase of the thickness of Cu Layer, S of L10 FeNi film increase at deposition temperature of 300oC while the c/a ration for the lattice distortion has no clear relation with the thickness of Cu layer.

NNF 2538, Poster, Surface multi-treatments of nanoporous SiO2-derived dielectric layers for electrochemically-plated copper metallization

Chen Sung-Te1;Hsu Yen-Che2; Lai Wei-Tsang3; Chen Giin-Shan4
1Department of Electronic Engineering, Hsiuping University of Science and Technology; Taiwan
2Department of Materials Science and Engineering, Feng Chia University;Taiwan

Chemically vapor deposited (CVD) SiO2-derived films with nano-sized (2−5 nm) porosity and dielectric constants of 2.6 or less are currently a key type of inter-metal dielectric layers (IMDs) for copper interconnects of high-performance integrated circuits. These nanoporous dielectric layers have internal voids and surface open-pores, along with weak, low-polarization bonds (e.g., CH3). Therefore, upon treatments by the back-end processing steps, including thermal annealing, plasma ashing, UV-light curing, aqueous (electrochemical) solution copper-plating, etc., degradation of the nanoporous IMD itself and IMD/copper wiring systems is readily to occur due to IMD damage, copper peeling, aqueous solution penetration, or materials intermixing. In this study, Black Diamond II (DB II with chemical formula of SiOC:H), a leading nanoporous CVD dielectric layer, is examined as a representative case for the SiO2-derived nanoporous IMDs, demonstrating the feasibility of using a sequence of surface multi-treatments to resolve the above-mentioned issues. Fourier transform infrared and synchrotron x-ray absorption spectroscopies indicate that pretreatments of DB II by vacuum plasma using adequate conditions induce a nitrogen-contained surface layer while still keeping its dielectric and insulation characteristics normal. The plasma pretreatments have an additional effect of converting the originally hydrophobic DB II surface to highly hydrophilic surface, the contact angle of water droplet being reduced substantially from 90o to 5o. In contrast to the pristine hydrophobic BD II, the plasma-pretreated hydrophilic counterpart allows the SAMs to be uniformly anchored onto the water-wetted surfaces. The roles of SAMs, in terms of acting as a passivated layer, facilitating the plating of Cu films, and improving the process/material integration of nanoporous SiOC:H and Cu, are currently under investigation.

NNF 2541, Poster, Multiple High-k Tunneling Layers for High Performance Gd2O3 Nanocrystal Memory Application

Wang Jer-Chyi;Chen Chia-Hsin ; Lin Chih-Ting; Huang Po-Wei; Chen Yu-Yen; Lai Chao-Sung
Elctronic Engineering Dept., Chang Gung University; Taiwan

Recently, the Gd2O3 nanocrystal (Gd2O3-NC) memory performed by the bandgap offset between the crystallized Gd2O3 dot and the amorphous Gd2O3 dielectrics has been demonstrated. The Gd2O3-NC memory exhibited good performance with an optimized annealing process. It has also been reported that BE-SONOS by using SiO2/SiN/SiO2 (ONO) as the tunneling layer can be the future advanced memory application. In this paper, the Gd2O3-NC memory with high-k Al2O3/HfO2/Al2O3 (AHA) multiple tunneling layers was investigated owing to higher dielectric constant of AHA than ONO dual-tunneling layer. In this research, various thicknesses of multiple tunneling layers were conducted. In order to compare the memory performance, the thickness of middle HfO2 layer was fixed, and the thicknesses of 1st Al2O3 and 2nd Al2O3 were adjusted. We observed that higher program speed can be obtained for thinner 1st Al2O3 layer (~1V VFB shift at 9V gate voltage), while the higher erase speed can be obtained for thinner 2nd Al2O3 layer (~-1V VFB shift at -13V gate voltage). The higher memory window in the programming stage was resulted from the higher tunneling current through thinner 1st Al2O3 layer, while the one in the erasing stage was resulted from the higher tunneling current through thinner 2nd Al2O3 layer. The better data retention can be obtained for the AHA multiple tunneling layers because of the thicker physical thickness. There were two charge trapping levels, which were observed from the retention results. The estimated deep trapping level is about 0.06~0.08eV below the silicon conduction band, while the shallow trapping level is about 0.1~0.13eV below the Gd2O3-NC conduction band. The endurance test showed that the ~1V memory window has no significant degradation after 104 programming/erasing operation time. The improvement of the memory performance can be explained by the proposed band diagram model.

NNF 2543, Poster, METALLIZED POROUS SILICON FILMS FOR ETHANOL VAPOUR SENSING

KAYAHAN ERSIN;
Kocaeli University, Gebze MYO, , 41800, Hereke, Kocaeli; Turkey

Porous silicon films (PSF) have drawn considerable attention for both chemical and bio sensing applications. Its luminescent properties, large surface area and compatibility with silicon-based technologies have been the driving force for this technology development. In this study, electrical and optical properties of PSF under different ethanol vapor levels and mechanisms of the sensing were investigated. PSF are fabricated by anodic dissolution in hydrofluoric acid solution. The PSF surfaces were metalized by immersing into solutions containing metal salts (i.e. LiNO3, AgNO3 and NaNO3) using immersing plating method. The surface bond configurations of PS were monitored by Fourier Transmission Infrared Spectroscopy (FTIR). The experimental results suggested that the metallization of PSF surface enhances the sensibility of ethanol vapor.

NNF 2544, Oral, Simulation of Thin Film Nucleation Kinetics on Liquid Substrates

Cheng Ting;P Anantha; Wong Chee Cheong
School of Materiasl Science and Engineering, Nanyang Technological University; Singapore

The morphology difference of metallic films formed on solid and liquid substrates have not been thoroughly investigated before. To obtain direct analyzable results, real-time considered computing simulation was introduced in investigation. As representatives of physical and chemical properties of substrates, molecular frequency and adsorption probability are utilized as the key parameters. Conventional equations and an adapted time algorithm are employed to guarantee a correct, comparable and efficient simulation technique. The results show the non-uniform morphology and low coverage were observed under ‘liquid-substrate conditions’ which are in agreement with the experimental conclusion. The method can be further applied for predicting the film morphology for various condensate/substrate systems with known conditions.

NNF 2547, Poster, Periodic Si nanostructures fabricated by nanosphere lithography and anisotropic wet etching

LIN Y. H.1;LEE S. W.2; CHENG S. L.1
1Dept. of Chem. & Mater. Eng., National Central University; Taiwan
2Inst. of Mater. Sci. & Eng., National Central University;Select your country!

Surface-patterned Si nanostructures have attracted a lot of attention due to their unique physical and optical properties and potential applications in various fields, especially in advanced nanoelectronic and photovoltaic devices. To produce periodic nanostructure arrays on Si substrates, a variety of lithography techniques have been developed. In this study, we propose a new, facile and efficient method to fabricate size-tunable periodic Si nanostructure arrays, which is based on the plasma modified nanosphere lithography with an anisotropic wet chemical etching technique. No additional thin-film deposition equipments and metal film hard masks are needed in this process. From SEM and AFM observations, it is clearly demonstrated that large-area, well-ordered nanohole structures were successfully fabricated on the surfaces of single-crystal Si substrates after appropriated O2 plasma treatments and subsequent site-selective chemical etching. The Si nanohole arrays exhibit the same hexagonal arrangement as the initial colloidal nanospheres template. The size, shape, and spacing of Si nanoholes could be controlled by adjusting the O2 plasma treatment conditions and the wet etching duration. The experimental results present the exciting prospect that with appropriate controls, the plasma modified nanosphere lithography technique promises to offer an effective patterning method for fabrication of regular nanohole arrays on various Si-based substrates without complex lithography.

NNF 2552, Poster, Growth of self-assembled InGaN quantum dots on Si (111) at reduced temperature by molecular beam epitaxy

Chin Che Woei;Hassan Zainuriah; Yam Fong Kwong; Ahmad Mohd. Anas
School of Physics, Universiti Sains Malaysia; Malaysia

Recently, the investigations of semiconductor quantum dots (QDs) have been very extensive. These are fuelled by the unique physical phenomena and potential application. The study of QDs, particularly InGaN QD structures show very promising. There have been reported that the performance of InGaN laser would be improved enormously by introducing InGaN QDs into the device active layer, this led to higher brightness, lower threshold currents and better temperature stability. From the literature, the growths of self-assembled InGaN QDs by RF plasma assisted MBE on Si (111) at reduced temperature are relatively less investigated as compared to sapphire. In this paper, we report the growth of InGaN-based QDs by RF plasma-assisted molecular beam epitaxy (RF-MBE) on Si (111) substrate at low temperature, i.e 500oC without growth interruption. Growing surfaces of thin film were monitored in situ by reflection high-energy electron diffraction (RHEED). During growth, we observed the change of RHEED patterns from streaky to spotty, indicative of the change of transition from 2-dimensional to 3-dimensional growth and x-ray diffraction (XRD) measurements confirmed the presence of InGaN. The morphology of the surface was observed by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The optical properties of the InGaN QDs will investigated by photoluminescence.

NNF 2558, Oral, Characterization of Electroplated Multilayered Nanoporous Platinum Films on Silicon

Lee Yi Jae;Park Jae
Department of Electronic Engineering, Kwangwoon University; Korea (south)

Multilayered nanoporous Pt (NPt) thin film on silicon substrate was newly developed and characterized for highly sensitive and CMOS integrable bio/chemical sensor and fuel cell applications. The fabricated multilayered NPt film exhibited extremely high roughness factor and H2O2 sensitivity of 1140.4 and 585.7 μA/mM•cm2, respectively. In this research, a simple and effective methodology is presented for fabricating the multilayered NPt thin films on silicon substrate. They were fabricated by using C16EO8 surfactants and hexachloroplatinic acid based electroplating technique. For forming the multilayered NPt film, this sequence was repeatedly performed. The multilayered NPt thin films with various thicknesses ranged from 0.4 to 4 um were characterized and compared (Figure 3) by using cyclic voltammetric method in 1M sulfuric acid (scan rate; 50 mVs-1). Their roughness factors were calculated as 107.9, 777.7, and 1140.4 by using the measured cyclic voltammograms (geometric surface area; 0.03 cm2). The multilayered NPt thin films showed large response current as an increment of layer number due to extremely enlarged surface activation area. The amperometric current of the multilayered NPt thin films was also measured to the consecutive addition of 1 mM H2O2 in continuous stirred PBS solution (pH 7.4, applied potential; 0.4 V). Their sensitivities were 325.5, 391.4, and 585.7 μA/mM•cm2 at the H2O2 concentration ranged from 1 to 7 mM, respectively, which were much larger than the previously reported ones.

NNF 2559, Poster, Characterization of High sp3 Diamond-Like Carbon Films Synthesized by Cathodic Arc Activated Deposition Process

Wang Da-Yung;Chen Wei-Chih; Lin Wei-Cheng
Dept. Materials Science and Engineering, MingDao University; Taiwan

The diamond-like carbon (DLC) film has been widely used in the cutting and forming industries for its superb properties of high hardness, low friction coefficient, high wear resistance, and chemical inertness. In this study, an amorphous hydrogenated carbon film (a-C:H) was synthesized by using a cathodic-arc activated deposition (CAAD) process. The CAAD process consisted of a PVD stage, where a metallic and nitride transition layers were deposited, and a follow-up PECVD stage, where the super-hard CrxC/DLC gradient coating was deposited. During the later PECVD CVD stage, the energetic metal plasma catalyzed the decomposition of the hydrocarbon gas (C2H2) and induced the formation of the final gradient carbon film. In order to maintain the sp3/sp2 ratio of the DLC film with specific tribological properties, the deposition parameters have to be regulated through a control mechanism. Results of this study demonstrated that the carbon bond ratio of DLC is closely related to the flow ratio of the reactive gas (C2H2/( C2H2+ N2)). According to the results of Optical Emission Spectrometer (OES) analysis, we found that there existed a transition point of 63% C2H2 flow ratio (C2H2/( C2H2+ N2)) within the current experimental settings. The formation of CrN proceeds in the mixed reactive N2/C2H2 gases before the C2H2 partial pressure reached the transition point. The reaction mechanism switched from CrN to CrCx at the transition point and finally led to the formation of superhard DLC(a-C:H). The formation mechanism of metal carbides and DLC during the CAAD process was analyzed by using optical emission spectroscopy and XRD. The tribological tests, electron microscopy, and Raman spectroscopy were employed to characterize the microstructure and carbon bond properties of DLC coatings.

NNF 2561, Poster, Characterization of Superlattice CrN/AlN and CrN/ZrN Coating for Semiconductor Packaging Applications

Wang Da-Yung1;Chen Wei-Chih2; Tzeng Weh-Hshing3
1Dept. Materials Science and Engineering, MingDao University; Taiwan
2Dept. Materials Science and Engineering, MingDao University;Taiwan
3Dept. Materials Science and Engineering, MingDao University;Taiwan

Owing to its excellent tribological properties and high temperature resistance, the PVD CrN coating has been adopted as the replacement for the conventional hard chrome plating for IC packaging dies. To further extend the service life of the packaging dies against the hard corrosive of the packaging resin, the protection mechanism by using the superlattice CrN/MeN(Me:Al or Zr) coating is evaluated. The X-ray diffraction analysis revealed that the AlN layer in CrN/AlN coatings possesses a metastable cubic structure instead of its equilibrium hexagonal structure when deposited at a periodic thickness < 8 nm. The CrN/AlN thin film demonstrated the B1-NaCl lattice structure. The CrN/ZrN coatings synthesized at Λ = 4 nm revealed obvious satellite peaks. The microhardness increased with the decreasing of the periodic thickness and reached the maximum value of 28.1 GPa and 32.3 GPa for CrN/AlN and CrN/ZrN at the periodic thickness Λ = 4 nm, respectively. After exposing to oxidation environment between 100 oC and 1000oC, the CrN/AlN superlattice thin film showed superior oxidation resistance below 870 oC with a low relative weight gain of 0.2%. For IC packaging application, both CrN/AlN and CrN/ZrN superlattice thin films are durable enough to withstand the abrasive and corrosive attack. The CrN/ZrN shows higher hardness for a better mechanical strength, and the CrN/AlN is favorable when higher thermal stability is required. Keyword: IC packaging die, superlattice, CrN/AlN, CrN/ZrN

NNF 2568, Poster, Thermal Resistive Properties by Plasma Polymerization Tin-organic Thin Film and Surface Grafting on PNIPAAm Nanocomposite Hydrogel with Nanogold Particles

Chen Ko-Shao1;Chou Chin-Yen1; Liao Shu-Chuan2; Tsai Hsin-ting1
1Department of Materials Engineering, Tatung University, Taipei, 104, Taiwan; Taiwan
2Center for Thin Film Technologies and Applications, Ming chi University of Technology, New Taipei city, Taiwan;Taiwan

To develop a new type temperature sensor device by simple fabrication, a thermosensitive gold nanoparticles (Nano-Au) layer was immobilized on the electrode by plasma treatment and graft polymerization. Gold nanoparticles were reduced by trisodium citrate combined with hydrogen tetrachloroaurate(III) tetrahydrate (chloroauric acid) and modified with 11- mercaptoundecanoic acid (MUA) by the self-assembly monolayers (SAM). In this study, UV-induce grafting polymerization of N-isopropylacrylamide (NIPAAm) was carried out by two steps, using O2 plasma pretreatment of the surface on MUA SAM modified Nano-Au to form the peroxide groups on Nano-Au (MUA), and then subsequently using UV light to induce grafting with thermo-sensitive polymer to immobilize on electrode which modified with tetramethyltin (TMT) and O2 gas mixtures plasma. Using simple environment test to measure resistance, the LCST of Nano-Au (MUA) mixed with NIPAAm hydrogel was found to be 31°C. At ambient temperatures higher than LCST, the electrode resistance decreases. Moreover, the nanocomposite hydrogel can prevent the sensor device from contacting aqueous solution directly which causes the device damage by working current. The surface morphology of composite hydrogel was observed by SEM.

NNF 2577, Poster, Synthesis of silver nanowire by polyol method for transparent conductive film application

Huang Jung-Jie1;Wu Menq-Jion2; Chao Ching-Hsun3; Chen Chao-Nan4; Hsueh Yu-Lee2
1Department of Materials Science and Engineering, MingDao University; Taiwan
2Department of Mechatronics Engineering, National Changhua University of Education;Taiwan
3Dow Advance Materials EM, Dow Chemical;Taiwan
4Department of Computer Science and Information Engineering, Asia University;Taiwan

In the study, we used the polyol method to synthesize silver nanowire, and the use of silver nitrate (AgNO3) as the precursor for seeds. Unlike other studies, we not use the metal salts (PtCl2, NaCl) as the seed precursors before the synthesis of silver nanowires. The experimental results show that the different synthesis temperature, Poly(N-vinylpyrrolidone) (PVP) molecular weight, the concentration of reactants and the addition rate of silver nitrate will affect the growth characteristics of silver nanowires. SEM, UV-vis spectra and XRD have been employed to characterize the silver nanowires. When the synthesis temperature is higher than 180oC, the nucleation rate is too fast. Therefore, the particles are homogeneous nucleation and the formation of silver particles. When increasing the concentration of PVP, the diameter of the silver nanowires will be widened to cause a smaller aspect ratio. This study successfully prepared silver nanowires with a diameter of 170 nm and a length of 20 μm. Finally, the transmittance and sheet resistance were measured by UV-VIS-NIR spectrophotometer and four-point probe I-V test, respectively. The solution-type silver nanowire thin film shows high transmittance, low sheet resistance and can be used for transparent conductive film application.

NNF 2578, Poster, Strong Quantum Confinement Effects in PbS Nanostructures Prepared by Chemical Bath Deposition

Abbas Muna1;Shehab Alia2; Hassan Noor3
1Baghdad University College of Science Physics Department; Iraq
2Baghdad University College of Science Physics Department;Iraq
3Baghdad University College of Science Physics Department;Iraq

PbS thin films are good materials for antireflection coatings and for solar thermal applications in flat-plat collectors, house heating for solar chick brooding, etc. Nanocrystalline PbS thin films were deposited on glass substrates using chemical bath technique at different solution temperatures and various deposition times. The thickness of the films was in the range (500-1000nm). The structure and the crystallite size of these films were studied by X-ray diffraction and atomic force microscope AFM. The influence of thermal treatment under various annealing temperatures on the crystal sizes has been studied. Optical energy gaps were calculated depending on the effective mass models and compared with the experimental data. Increased the optical energy gap with decreasing crystals size is attributed to quantum confinement.

NNF 2589, Poster, Study of High Quality and Output Power of InGaN-based LED Grown on Si (111) by Inserting Porous SiNx Thin Films

FANG Yen-Hsiang;XUAN Rong
Electronics and Opto-electronics Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan, R.O.C.; Taiwan

From the cross section transmission electron microscopy (TEM) measurement of GaN on Si (111), it was taken under the (11-20) two beam diffraction condition. Thus, both edge and mixed type dislocations are visible. Dislocation termination occurs at the AlGaN/GaN interfaces. Moreover, many dislocations in the GaN immediately above the last AlGaN intermediate layer incline, leading to dislocation annihilation and compressive stress relaxation. Clearly, a large number of dislocations are effectively stopped from propagating due to the presence of the SiNx interlayer and finally horizontal dislocations are formed by bending through the enhanced lateral growth of islands. This all contributes to an efficient reduction of the total dislocation density in the top GaN layer to smaller than 109 /cm2. Moreover, the output power and the operation voltage as functions of the dc injection current are measured. The forward voltage and output power of LED on Si (111) is 3.37 Vf at 20 mA, and 4 mW at 20 mA, respectively. After thin GaN process, the output power is the triple more than that without removing the Si substrate.

NNF 2594, Oral, Research of ultrahigh Ti-Al-C-N nanocomposite coatings

zhang xuhai;guo junjie; chen mingwei; jiang jianqing; zeng yuqiao
southeast university; China

The effects of Carbon addition and heat treatment on mechanical and tribological properties of TiAlCN coatings were investigated. A proper amount of carbon addition resulted in a fine nanocrystallite + amorphous composite structure, which exhibited ultrahigh hardness and low coefficient factor. The heat treatment manipulated the distribution of carbon in TiAlCN coatings similar to the effect of aging and thus further improved the coating mechanical and tribological properties.

NNF 2611, Oral, Field emission studies from various nanocomposite Films

Patra Rajkumar1;Ghosh Santanu2; Jha Menaka3; Ganguli A. K.4; Vankar V. D.5
1Department of Physics, Indian Institute of Technology Delhi, New Delhi-110 016,; India
2Department of Chemistry, Indian Institute of Technology Delhi, New Delhi-110 016;India

We report here detailed field emission studies from various nanocomposite films like (i) metal-insulator nanocomposite (ii) ZnO-CNT nanocomposite and (iii) CeB6 CNT nanocomposite Films in an indigenously developed high vacuum compatible field emission (FE) set up. The set up is made in diode configuration, with a precision control of electrodes separation (down to 5 mm) and tested upto a pressure of 5 ´ 10-7 torr with the help of a rotary and turbo molecular pump (TMP). The operation of the instruments and data analysis is done through a PC interfaced with the system. Samples are prepared both by physical vapor deposition (PVD) techniques and chemical routes. The salient results obtained from the FE studies are: (i) a significant improvement of field emission current associated with an appreciable reduction in turn on field from CeB6 nanorods , ZnO-CNT and CeB6-CNT films and (ii) morphology and nanoparticle size dependent field emission from metal nanoparticles embedded in thin silica matrix, a novel material for field emission studies. The results are interpreted in the framework of Fowler Nordheim (F-N) theory. Key words: Field emission, Carbon nanotube, Cerium Hexaboride, Nanocomposite, F-N theory.

NNF 2616, Oral, Deposition of AlN films with controlled crystallinity by UV-light assisted sputtering at room temperature

Feng Bin1;Jin Hao1; Dong Shurong1; Jian Zhou1; Wang Demiao1; Luo Jikui2
1Dept. Info. Sci. & Electron. Eng., Zhejiang University; China
2REET, University of Bolton;United Kingdom

Aluminum nitride (AlN) films with (002) and (100) oriented crystal structures have been widely used in electronic and acoustic device applications owing to its excellent electro-acoustic properties. However deposition of high quality AlN is still very challenging. Although a lot of methods have been developed, most of them require a high substrate temperature for AlN deposition, which limits its applications, especially in flexible electronics. A ultra-violet (UV) assisted reactive RF magnetron sputtering deposition method for AlN thin film at room temperature is proposed and developed. AlN films were deposited at various conditions with and without UV-light exposure, and the crystal structures of the films were investigated by XRD and SEM. All depositions were performed without intentional substrate heating, and the substrate temperature was confirmed to be less than 100C. The results show that UV-light exposure enhances the AlN deposition rate for all conditions. AlN thin films deposited at various conditions are all amorphous-like structure if they were deposited without UV light exposure. They become either (002) or (100) oriented crystal structures with large grain sizes when they were deposited with the assistance of UV-light. At high sputtering powers, (002) oriented columnar AlN crystal is dominant; and (100) oriented crystal structure becomes dominant when the N2/Ar flow ratio was increased. UV-light enhanced Al ionization is believed to be responsible for the increased deposition rate and well-aligned crystal orientation of the AlN at room temperature. The results demonstrate the great potential of UV-light assisted sputtering for deposition of high quality AlN films at low temperature.

NNF 2617, Oral, Effect of Sputtering Power on Optical Properties of Amorphous Silicon Carbon Nitride Films Grown by Magnetron Sputtering Technique

JAMAL Ilyani Putri1;ASPANUT Zarina1; NAYAN Nafarizal2; ABDUL RAHMAN Saadah1; MOHAMED ALI Riyaz Ahmad2
1Physics Dept., University of Malaya; Malaysia
2Faculty of Electrical and Electronic Engineering, Universiti Tun Hussin Onn Malaysia;Malaysia

Silicon carbon nitride (SiCN) films deposited in by magnetron sputtering in Ar/N2 ambient. The effect of applied power in the range of 120 to 400 W was studied in term of optical and structural properties of the deposited films. Thickness of the SiCN film was found to increase with the power. Scanning electron microscopy image shows the films having an even surface morphology. X-ray diffraction studies revealed the amorphous nature of the films. The optical result shows that the ultra-violet absorption spectra in the region of 300-400 nm increases with the increase in power. The optical band gap was found to decrease with power due to the corresponding increasing in carbon content. Photoluminescence emission intensity decreased with the increase in power. The results above were correlated with the silicon, carbon and nitrogen and argon contents in the gas phase measured by optical emission spectroscopy.

NNF 2618, Oral, One-step hybrid pulse anodization of aluminum foil and thin film

Chung C.K.;
Deparment of Mechanical Engineering, National Cheng Kung University; Taiwan

The anodic aluminum oxide (AAO) has attracted more and more researches since its porous structure was discovered for many nano-enabled applications in electronic, photonic, optoelectronic, energy, catalyst and bio devices. Conventional AAO templates were performed using two-step direct current anodization (DCA) at low temperatures of 0~5 °C in order to obtained well-ordered pore structure. That is, the rough AAO formation at first anodization was removed and then followed by second anodization. In fact, less application required near-perfect pores arrangement. Moreover, this multi-step process is difficult to perform in anodization of aluminum thin film due to the limited thickness. In this article, we have proposed the hybrid pulse anodization (HPA) combining a normal positive with a small negative potential difference at relatively high temperatures of 15~25 °C which could overcome the limitation of conventional low-temperature AAO process. In order to reduce anodizing times and maintain the pore quality, some important factors should be investigated. The HPA method can enhance AAO growth rate at high temperatures as well as high distribution uniformity and circularity of porous structure compared to one-step DCA. Moreover, the effect of surface morphology and post-treatment like phosphoric acid immersion time was also studied by one-step HPA. The difference between anodization of aluminum foil and thin film were compared. The same anodization parameters resulted in distinct pore structures in Al film due to limited thickness or varied grain size.

NNF 2630, Oral, The nanostructures of Papilio blumei's colorful wing scale

Lo Mei Ling;Lee Wen Hsin; Lee Cheng Chung
Department of Optics and Photonics, National Central University.; Taiwan

Butterfly’s wing has paid great attention due to its attractive iridescence. The optical properties are closely related to its structure. Under optical microscope images, the wings of Papilio blumei are covered with millions of scales obviously. The dimension of one scale is about 150 ~170μm in length and 83~87μm in width for green band and cyan tail. In addition, each cover scale is the sealed structure which its surface consists of an ordered array of concaves ( which its diameter and depth are about 5μm and 1.2μm respectively ) and ridges are found to run longitudinally from one end to the other. The average distance between neighboring ridges on a cover scale is about 8~9μm, which is beyond the visible light range. Furthermore, the inner mode of the scale is multilayer thin-film structures that composed of air and chitin layers. The periodic multilayer structures produce bright iridescence color. In order to investigate which structural parameters affected the characteristics of reflectance spectra and formed the iridescent green or cyan color on wing’s body or tail part. Therefore, the simulation using thin-film design software Macleod and finite-difference time-domain method (FDTD) was carried out. The shape and size of the simulated model was set according to the SEM cross-section images of Papilio blumei’s wing scale. In our study, we mimic the concaves of the scale and using complex deposition technologies, including electron beam evaporation and sputtering to stake the multilayer. The multilayer consisted of a thin carbon film and alternating high and low refractive index materials stack (TiO2 and SiO2). The substrate is silicon. Finally, the 3D photonic crystal structure was established and the optical properties of the Papilio blumei’s wing scale were showed.

NNF 2642, Poster, Direct assembly of graphene and carbon nanotube for large-scale fabrication of nano devices and structures using solution processing at low temperatures

Kim Kyeong Heon;Kim Su Jin; Lee Jae Hoon; An Ho Myoung; Kim Tae Geun
Korea University; Korea (south)

Since the discovery of carbon nanotubes (CNTs) in 1991 by Iijima, they have been paid attention as important transparent conductors, which can take the place of indium-doped tin oxide (ITO), due to their high carrier mobility and transmittance over a wide spectral region. In addition, a high aspect ratio of the CNT materials leads to low percolation thresholds, and eventually very little material is needed for conduction. On the other hand, the graphene, a single layer of carbon, has also shown potential advantages as electrical conductors since its experimental discovery in 2004. It is essentially a CNT cut along its axis and unrolled to lay flat. It can provide conduction pathways to a greater area per unit mass than CNTs and have higher transmittance. Despite these advantages, the precise assembly of nano materials such as CNT and graphene is still considered as an important challenging task for their practical application to conventional devices. Recently, various types of thermal or plasma-enhanced chemical vapor deposition (CVD) methods have been used for assembling CNT and grapheme nano-materials. However, they involve high-temperature and vacuum conditions, making it costly and quite complicated. Therefore, the development of a dry-chemistry-free, inexpensive and facile technique for the fabrication of CNTs and graphene, that retains the nano materials alignment, is quite important for their practical use to the next-generation opto-electronic devices. We have studied a solution process involving the dispersion of the CNT and graphene into the liquid, in order to solve the problem related to the dry-assembly of the CNTs and grapheme [1]. In this work, a direct assembling method of the CNTs and graphene for large-scale fabrications of nano devices and structures, using solution processing at low temperature, are reported. Since all the processing steps are compatible with conventional microfabrication facilities, the proposed method is expected to be readily accessible to the present semiconductor industry. Details on the experimental results and discussion will be presented at the conference. [1]""Processing technique for SWCNT-based sensor arrays,"" Kyeong Heon Kim et al., J. Nanosci. Nanotechnol., (2011 in press)

NNF 2647, Poster, Structural and mechanical properties of TaN(Ag,Cu) nanocomposite thin films

Lin Y. J.1;Hsieh J. H.1; Chang S. Y.2
1Dept. of Materials Engineering, Ming Chi University of Technology; Taiwan
2Dept. of Materials Science and Eng., National Chung Hsing University;Taiwan

TaN-(soft metal) nanocomposite thin films have been shown to have good mechanical properties. This study aims at comparing the structural and mechanical properties of TaN-(Ag,Cu) nanocomposite films with those of TaN–Cu, TaN-Ag films. TaN-(Ag,Cu) nanocomposite films were deposited by three-target reactive co-sputtering on Si and M2 tool steels with the variation of Ag+Cu/TaN ratios. They were then annealed using RTA (Rapid Thermal Annealing) at 400 C for 2~8 minutes to induce the nucleation and growth of metal particles in TaN matrix and on film surface. After being characterized using XRD and FESEM, the samples were tested using a nano-indenter and tribometer. It is found that the hardness of the films are affected by soft metal contents and annealing time. The hardness can reach 34 GPa on TaN-(Ag,Cu)-2 at.%, after rapid thermal annealing for 4 minutes. The friction coefficient and wear could be much lower for the copper containing samples when tested in argon environment.

NNF 2656, Oral, Control of aspect ratio of Si nanowires using hydrogen diluted silane at different hydrogen flow rate

Chong Su Kong1;Goh Boon Tong1; Zarina Aspanut1; Muhamad Rasat Muhamad1; Dee Chang Fu2; Saadah Abdul Rahman1
1Low Dimensional Materials Research Centre, Department of Physics, Faculty of Science, University of Malaya.; Malaysia

In this work, silicon nanowires were synthesized by indium catalyst using hot-wire chemical vapour deposition technique. Four sets of samples were prepared at different hydrogen flow rate of 0, 50, 100 and 150 sccm, keeping the silane flow rate at 5 sccm. Field emission scanning electron microscopy images show that aspect ratio of the silicon nanowires decreases with the increase in hydrogen flow rate. While, X-ray diffraction and micro-Raman measurements indicate that the crystallinity of the samples increases with the increase in hydrogen flow rate. The role of hydrogen on the reduction in the aspect ratio and enhancement in the crystallinity of the silicon nanowires are discussed. The field emission properties for the different aspect ratio of silicon nanowires were also studied.

NNF 2658, Poster, Microstructure and crystallization behavior of Ge/GeCu bilayer for blue laser optical recording application

Ou Sin-Liang1;Kao Kuo-Sheng2; Shih Wei-Che2; Chen Sheng-Chi3
1Department of Materials Science and Engineering, National Taiwan University; Taiwan
2Department of Computer and Communication, SHU-TE University;Taiwan
3Department of Materials Engineering, Ming Chi University of Technology;Taiwan

Amorphous silicon (a-Si) was applied to write-once blue laser optical recording media due to its low cost and simple fabrication process. However, its high crystallization temperature (700 °C) was the main limitation to optical recording. Metal induced crystallization can dramatically reduce the crystallization temperature of a-Si, later, the metal/Si bilayer and metal-doped Si single layer were proposed for use in write-once blue laser optical disc. On the other hand, amorphous germanium (a-Ge) has the similar physical and chemical properties as Si, and the crystallization temperature of a-Ge is only 470 °C. In this work, the GeCu (16 nm) and Ge (3 nm)/GeCu (16 nm) films were deposited on nature oxidized silicon wafer and glass substrate by magnetron sputtering. The ZnS-SiO2 films were used as protective layers. The composition of GeCu layer was confirmed to be Ge67Cu33 by electron probe micro-analyzer (EPMA). The crystallization temperature of Ge in GeCu (16 nm) was 392 °C, indicating the addition of Cu metal can reduce the Ge crystallization temperature effectively. Moreover, the crystallization temperature of Ge can be further decreased to 362 °C by inducing the 3-nm-thick Ge layer to form Ge (3 nm)/GeCu (16 nm) bilayer. From TEM measurements, the Cu3Ge phase both appeared in GeCu and Ge/GeCu films, and Ge crystallization formed in these films after 450 °C annealing. Especially, the Ge crystallization with various shapes such as rod, rectangle and hexagon appeared in annealed Ge/GeCu bilayer, which was not found in the annealed GeCu film. Furthermore, the Ge/GeCu bilayer has high optical constant above 20% (at wavelength of 405 nm) between as-deposited and annealed states, showing high potential in blue laser optical recording.

NNF 2660, Poster, Influence of Rapid Thermal Annealing Time on the Growth of Gold Nanoparticles embedded in SiOx Film

Kee Wah Chan;Boon Tong Goh; Abdul Rahman Saadah; Aspanut Zarina
Low Dimensional Materials Research Centre, Department of Physics, University of Malaya; Malaysia

In this study, nanocomposite material consisted of silicon suboxide (SiOx) film embedded with gold nanoparticles (Au NPs) was synthesized using hybrid technique combining hot wire evaporation and plasma enhanced chemical vapour deposition (PECVD) method. As prepared films were then rapid thermal annealed at constant temperature of 800oC for different annealing time. Depth profiling analysis has confirmed the embedded in structured of Au/SiOx film. FESEM, XRD, UV/VIS/NIR and PL spectroscopy have been utilized to study the structural and optical properties of Au/SiOx film annealed at different time of 30, 60, 90 and 120 s in atmospheric ambient. Growth of Au NPs was dependent on the thickness of Au and SiOx film. Spherical-shaped Au NPs were found to enlarge in size and narrow in size distribution with the increase in annealing time. Intensity of the sharp PL peak located at 580 nm increased with the annealing time. PL peak only red-shift to 590 nm as annealing time of 120 s was achieved. Au crystalline diffraction peak and localized surface Plasmon resonance (LSPR), which is dependent on annealing time, were clearly observed in the XRD and optical spectra.

NNF 2664, Poster, Deposition of transparent conductive AZO thin films using ozone assisted sol-gel method

Tseng Yung-Kuan1;Chen Yen-Cheng2; Pai Feng-Ming3; Wu Chao-Hsien4
1Department of Cultural Heritage Conservation, National Yunlin University of Science and Technology Douliou, Yunlin, 64002, Taiwan, Republic of China; Taiwan
2Graduate School of Materials Science, National Yunlin University of Science and Technology Douliou, Yunlin, 64002, Taiwan, Republic of China;Taiwan
3Graduate School of Materials Science, National Yunlin University of Science and Technology Douliou, Yunlin, 64002, Taiwan, Republic of China;Taiwan
4Graduate School of Materials Science, National Yunlin University of Science and Technology Douliou, Yunlin, 64002, Taiwan, Republic of China;Taiwan

This study used the sol-gel method for the deposition of transparent conductive AZO thin films and ozone for heat treatment. The results of XRD analysis show that the addition of ozone reduced the sintering temperature, resulting in a wurtzite crystal structure with high c-axis orientation. FE-SEM analysis of the surface revealed that the resulting AZO thin films are dense and smooth. AFM scanning results indicate that the thin films have low average surface roughness. The results of visible spectroscopy illustrate that the AZO thin films have better visible light transmittance than those deposited in air. A four-point probe measured the resistivity of the thin films at 10-3 ohm-cm. These results demonstrate the effectiveness of using ozone in the process of deposition to reduce the surface roughness of AZO thin films while improving the transmittance of visible light.

NNF 2671, Poster, Preparation and In Vitro Study of ZnO/PEGMEMA Core Shell Nanoparticles

Chung Ren-Jei;
Department of Chemical Engineering and Biotechnology, National Taipei University of Technology; Taiwan

The purpose of this study is the to prepare zinc oxide with specific nanostructures, including zinc oxide / PEG-MEMA polymer composite with core-shell structure through the sol-gel method. For the sol-gel method, zinc methacrylate was used as zinc source, absolute alcohol as solvent, sodium hydroxide as base, polyethylene glycol methyl ether methacrylate as surface modification agent, and azobisisobutyronitrile as the reaction initiator. The prepared ZnO nano particles emitted yellow light under UV light excitation respectively. The material was further tested for in vitro study. Through the cytotoxicity test (MTT) using L929 cell line, better biocompatibility was observed under the concentration below 10μg/mL for the material. Fluorescence images taken by a confocal microscope.showed that a large mount of materials were uptaken by the cells treated with 10μg/mL for 8h.

NNF 2676, Poster, Hydrodynamic lubrication transition of partially polished CVD diamond film

Miki Hiroyuki1;Tsutsui Atsushi2; Takeno Takanori3; Takagi Toshiyuki1
1Institute of Fluid Science, Tohoku University; Japan
2Graduate School of Engineering, Tohoku University;Japan
3Institute for International Advanced Interdisciplinary Research, Tohoku University International Advanced Research and Education Organization;Japan

The sliding speed dependence of the friction properties between a partially polished diamond film and metal have been investigated experimentally in the present research. Partially polished diamond films have low friction and low wear properties in air, and it is expected that the friction coefficient becomes very small at high sliding speeds. Polycrystalline diamond films are deposited on SiC substrates by hot filament chemical vapor deposition using a gas mixture of CH4 and H2. Partially polished diamond films were tested under different sliding speed conditions. The friction properties between the diamond films and an AISI440C pin under dry conditions were determined in air. A definite reduction in the friction coefficient was observed as the sliding speed increased; the speed at which this reduction began depended on the surface roughness of the film. Extremely low friction and noiseless sliding between films and counter metals was realized on polished diamonds as the sliding speeds increased. It is because contact pressure and lift force resulting from the gas flow between gaps are balanced. As a result, the transition to a hydrodynamic lubrication state occurs.

NNF 2687, Poster, Effect of coating oxidation state on ionic conductivity of nano-YSZ film

Tsung-Her Yeh;
Center for thin film technologies and applications, Department of Materials Engineering, Ming Chi University of Technology; Taiwan

The present paper is devoted to studies of the crystal structure and ionic conductivity of nano-YSZ films onto quartz insulator substrate obtained by reactive pulsed DC magnetron sputtering from a metallic Zr-Y alloy target using plasma emission monitoring. The sputtering conditions of oxygen flow rate and deposition rate were determined in order to produce the cubic- yttria stabilized zirconia (cubic-YSZ) as verified by X-ray diffraction. A higher rate of deposition is achievable when the sputtering mode of the Zr-Y alloy target is metallicas opposed to oxide. X-ray diffraction confirms the higher crystallinity of the fluorite cubic-YSZ film produced in the transition sputtering mode, compared to the as-deposited YSZ film fabricated in the reactive sputtering mode. However, the ionic conductivities of the nano-YSZ films respectively synthesized in the transition sputtering and reactive sputtering modes were measured using AC impedance analyzer and found the similar conduction characteristics. It indicates that the ionic conductivity of nano-YSZ films seems to independ on oxygen flow rate in the setpoint range from 80% to 100% (S=100 OIZr/OIZro). Formation of better incoherent interface between nano-YSZ film and quartz substrate is believed to be responsible for the excellent ionic conductivity in this study. Accordingly, these phenomena are then discussed regarding the metal-oxygen reactivity of Zr-Y alloy target, and the possibility to exploit oxygen deficient coatings deposited at high rate is presented owing to the deposition of dense and ultra-thin YSZ film for electrochemical devices application.

NNF 2692, Poster, Ionic liquid (1-n-ethyl-3-methylimidazolium tetrafluoroborate) Assisted Synthesis of MgO Nanoparticles by Sol-gel Method

Raja gopal Rajiv gandhi;Joghee Suresh; Sundaram Gowri; Samayanan Selvam; Mahalingam Sundrarajan
Industrial chemistry dept,Alagappa university; India

Magnesium oxide nanoparticles were successfully synthesized via sol-gel process using 1-n-ethyl-3-methylimidazolium tetrafluoroborate (EMIM BF4-) ionic liquid. The sol-gel products (Mg(OH)2) were annealed at 300 ºC for 2 hours. The annealed products were systematically investigated by X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). XRD pattern convey the purity, crystallinity and the mean particle size (12 nm) of the particles. SEM images evidence well defined surface morphology like leaves shape with particles in discrete state. Our experimental showed that the ionic liquid played an important role in MgO nanoparticles for the controlled size isomeric nanoparticles with distinct morphologies. The reported method, which is performed in ionic liquid under sol-gel condition, is friendly to environment. Keywords: ionic liquid, sol-gel, MgO nanoparticles, capping agent.

NNF 2715, Oral, Synthesis and characterization of CrZr-Si-N coatings using Cr-Zr-Si segment targets by unbalanced magnetron sputtering

Kim Dong Jun;Kim BomSok; Lee Sang-Yul
korea arospace university; Korea (south)

Abstracts Segment targets have several advantages for synthesize multi-component coatings, including that it is possible to deposit almost all materials and to synthesize various multi-component coatings without much difficulties. It does however remains a high challenge to control the composition and microstructure of the coatings synthesized using segment targets due to its geometrical distribution of segment targets. In this work, CrZr-Si-N films were synthesized by unbalanced magnetron sputtering with CrZrSi segment target. Three segment targets with various volume ratios of Si/(Cr+Zr) (each volume ratios : 1/11 , 1/5 and 1/3 ) were used to synthesize CrZr-Si-N films in this work. Characteristics such as crystalline structure, surface morphology, hardness and chemical composition as a function of the Si content were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), atomic force microscopy (AFM), microhardness testing system and energy dispersive spectroscopy (EDS). Experimental details will be presented. KEYWORDS Unbalanced magnetron sputtering, CrZr-Si-N thin films, segment targets, Microstructure, microhardness Acknowledgement This work was supported by a grant from the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy, Republic of Korea.

NNF 2733, Poster, THE SYNTHESIS OF Fe3O4 MAGNETIC NANOPARTICLES BY LASER ABLATION IN DIFFERENT SOLVENTS

Kariman Behjat Sadat1;Yousefi Hamid reza1; Aghamir Mojtaba(Farzin)2
1plasma physic research ceneter, science & research branch,Islamic Azad university, Tehran; Iran
2Physics Dep. University of Tehran;Iran

The emphasize of this paper is on the synthesis, protection and application of magnetic nanoparticles.The size and shape control of magnetic nanoparticles has been made by Laser ablation method. In this method, Nd:Yag Laser (1064 nm) was used for ablation. Synthesis of magnetic nanoparticles has long been of scientific interest due to their application in drug delivery, biomedicine, magnetic resonance imaging and treatment cancer tumor. Also, This article focuses on the physical properties and magnetic behavior of magnetic nanoparticles [2]. While a number of suitable methods have been developed for the synthesis of magnetic nanoparticles, successful technique for synthesis of magnetic nanoparticles is the laser ablation because it does not require expensive chemicals as chemistry technique and has been produced large-scale magnetic nanoparticles [1-3]. Moreover, this method has been successfully applied to metals.However the metals have useful magnetic properties which make them especially promising for applications in Biotechnology and Medicine [2].By the laser Nd:Yag (1064 nm) in different organic solvents such as: Ethanol, Aseton and toluene, synthesis of Iron-based the nanoparticles was investigated.In addition, regarding the protection against corrosion is a vital issue, two materials for coatings such as Au were used. However the stability of nanoparticles has been increased by use of metals shells.Structural analysis carried out by scanning electron microscopy,transmission electron microscopy, spectrophotometer and XRD revealed that various solvents and coatings have dramatic influences on both the dimension and the nanostructures of nanoparticles.Finally, some applications of Fe3o4/ Au Core/Shells nanoparticles in Biomedicine and treatment of cancer tumors were briefly studied. 1 .An-Hui Lu, E.L.Salabas and F.Schuth. Angew. Chem. Int. Ed.46 (2007) p.1223 2 .Q.A.Pankhurst, J.Conolly, S.K.Jones and J.Dobson. J.Phys.D: Appl. Phys. 36 (2003) p.167-174 3 .V.Amendola, P.Riello and M.Meneghetii. J.Phys.Chem.C.115 (2011) P.5140-5141

NNF 2736, Poster, Deformation and fracture of CrAlSiN nanocomposite coatings

Liu Shiyu1;Walter Claudia1; Vickers Mary1; Ding Xing Zhao2; Zeng Xianting2; Clegg William1
1Department of Materials Science and Metallurgy, University of Cambridge; United Kingdom
2Singapore Institute of Manufacturing Technology;Singapore

Cr-based nanocomposite coatings are attracting increasing attention for use as protective coatings in dry machining and aerospace applications where the components are consistently exposed to high temperatures. In this report, CrAlSiN nanocomposite coatings have been deposited with different silicon contents and at different substrate bias voltages using a lateral rotating cathode arc technique. Their composition, microstructure and mechanical properties were characterized using EDS, XRD and nanoindentation respectively and compared with CrN and CrAlN coatings deposited under the same conditions. The CrAlSiN films were somewhat harder than either the CrN or CrAlN films, although the internal stresses were lower than in the CrAlN. Micropillar compression was used to obtain the coatings’ flow stress. It was found that the constraint factor was close to that expected, and that the fracture behaviour of the CrAlSiN was different to that observed in the CrN and CrAlN.