Electronic structure at metal-semiconductor and metal-oxide interfaces

As devices shrink and nanoscale manufacturing becomes a distinct possibility, the interfacial properties of material systems become crucial in determining performance. Here we examine the effect of surface and interfacial atomic structure on the electronic properties using high resolution electron spectroscopy under in-situ conditions.

In the Co-Si system, we investigate the electronic structure of Co overlayers deposited on clean Si(001) surfaces. The initial bonding configurations are understood through photoemission spectroscopy, while subsequent nucleation and formation of Co silicide islands are observed by STM work. Such fundamental studies provide understanding of the driving mechanisms of nanostructure formation on semiconductor surfaces and could lead to further development of processing techniques for nanowires and nanodevices. (This work was done in collaboration with colleagues at NUS and IMRE.)

In several metal-oxide systems, we have investigated the interfacial band alignment using in-situ metal deposition on various high-k oxides. The nature of the metal growth and defects at the interfaces are observed through photoelectron spectroscopy. The work was done in collaboration with colleagues at IMRE and has strong implications for future CMOS devices and spin-tunnel junction devices.