Effect of Silane flow rate on microstructure of Silicon films deposited by HWCVD

Hydrogenated silicon films ranging from pure amorphous to those containing small crystallites in large crystalline fraction are prepared using the HWCVD technique without using any hydrogen dilution which is supposed to be necessary for the deposition of nanocrystalline Si films. The only parameter that is varied is Silane flow rate. The deposition rate ranges from 6–27 Å/s. The band gap of the films (1.8–2.0 eV) is high compared to the regular films, which is attributed to the improved short and medium range order as well as the presence of low density amorphous tissues in the grain boundary regions. The films show improved stability under long term light exposure due to more ordered structure and presence of hydrogen mostly as strong Si―H bonds.