Papers by Author: J.H. Hsieh

Abstract: Four alloy thin films were deposited on Si(100) by co-sputtering of various metals to investigate the formation of near-amorphous structure which may lead to featureless surface morphology and boundary-free structure. These thin films, Nb-Cr, Ta-Cr, Ti-Nb, and Zr-Cr, were examined using XRD SEM, and TEM. It is found that the forming ranges of near-amorphous thin films by co-sputtering are related to the difference in atomic size of the paired metals as well as their heat of mixing. Accordingly, Zr-Cr has the widest concentration range to form the near-amorphous structure. The addition of nitrogen during deposition can further enhance amorphization and reduce the surface roughness, until nitride phases are formed.

Abstract: X-ray photoelectron spectroscopy (XPS) has been used to characterize the Si nanocrystals (nc-Si) incorporated in SiO2 by ion implantation and subsequent thermal annealing. XPS results suggest that the as-implanted films contain a composition of a few suboxide SiOx (x<2). The dependence of XPS spectra on annealing temperature show that these suboxides decompose into SiO2 and Si nanocrystals. Due to the implanted Si+ depth profile, thermal annealing will lead to the formation of nc-Si with different sizes corresponding to the depth. Si0 peak shifts arising from the size effect of nc-Si can be clearly observed. Photo-induced charge effect from the nc-Si has been studied in this work. The potential wells induced by nc-Si in the SiO2 band gap substantially enhance the charging effect, which causes a significant shift in Si0 and C1s core levels.