Structure and Optical Characterization of Nanocrystalline Silicon Thin Films for Solar Cells

Abstract

AbstractEffects of very high frequency- plasma enhanced chemical vapor deposition (VHF-PECVD) using diluted ultrapure silane at higher dilution ratio (R>30) on microstructures and optical characteristics of hydrogenated nanocrystalline silicon (nc-Si:H) film were studied. Nanocrystalline silicon films were prepared by at RF power ranging from 50 to 300 W. It was found that the transition from amorphous phase to nanocrystalline phase occurred between 100 W and 150 W. The nucleation mechanism toward nc-Si:H near the transition point of amorphous phase was discussed based on transmission electron microscopy with atomic scale. Further, it is suggested from UV-visible spectroscopy that nc-Si:H films with the best optical properties would be obtained near the transition point from the amorphous phase to the crystalline phase.