A narrow process window for the preparation of polytypes of microcrystalline silicon carbide thin films by hot-wire CVD method

Abstract

Effects of deposition conditions on the structure of microcrystalline silicon carbide (μc-SiC) films prepared by hot-wire chemical vapor deposition (hot-wire CVD) method have been investigated. It is found from X-ray diffraction patterns of the film that a diffraction peak from crystallites from hexagonal polytypes of SiC is observed in addition to those of 3C-SiC crystallites. This result is obtained in the film under a narrow deposition conditions of SiH3CH3 gas pressure of 8Pa, the H2 gas pressure of 80–300Pa and the total gas pressure of 40–300Pa under fixed substrate and filament temperatures employed in this study. Furthermore, the grain size of hexagonal crystallites (about 20nm) on c-Si substrates becomes larger than that of 3C-SiC crystallites (about 10nm) for the films deposited under the total gas pressure of 36–88Pa. The fact that microcrystalline hexagonal SiC can be deposited under limited deposition conditions could be interpreted in the context of a result for c-SiC polytypes prepared by thermal CVD method.