Electronic Properties and Applications of Carbon Nanotubes
IV-8: Study of the Charge Transfer into/out of Carbon Nanotubes |
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Qing Zhang |
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Abstract |
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Carbon nanotubes (CNTs) have attracted much attention worldwide as they are regarded as a most promising material for molecular electronic device applications. CNTs are formed by graphitized closed seamless shells. Depending on the diameter and helicity, CNTs behave as one-dimensional metals or semiconductors, which by virtue of their great electrical current handling capability, high thermal conductivity and high mechanical toughness, represent an ideal material for molecular/nano electronic devices.
Our as-prepared CNT-field effect transistors have typical p-type CNT channel characteristic with on/off ratio of more than 104 and some of them exhibit a hysteresis response in the source-drain current vs the gate-voltage. At a large source-drain voltage, we observe negative differential conductance (NDC) with a peak-to-valley current ratio of about 2 even at room temperature. The peak voltage is also influenced by the gate voltage. This unique electrical characteristic is only found by our group so far. It is of a significant meaning of studying fundamental electron transport in low dimensional system and developing novel nanodevices. The primary objective of the proposal is to study the unique electronic properties systematically, including (1) study of the mechanism of charge transfer between carbon nanotubes (CNTs) and the metal electrodes and/or some elements adsorbed on the CNTs; (2) study of the mechanism of charge transfer into /out the carrier traps around the CNTs; (3) study of the influences of the charge transfer on CNT energy band structures and the influences of adsorbed elements on CNT morphological structures; (4) study of the influences of the charge transfer on the performance of CNT based field effect transistors (CNT-FETs) and to develop high quality n-type CNT-FETs and (5) study of electron transport in CNTs and relevant quantum phenomena. In the presentation, I shall also outline our processes of assembling CNTs into desirable patters and fabricating CNT electronic devices, such as CNT-FETs, CNT glucose detectors and CNT NH3-gas sensors. Relevant unique phenomena observed by us will be reported. |
