Variation of microstructure and transport properties with filament temperature of HWCVD prepared silicon thin films

Thin films of hydrogenated silicon are prepared by varying the filament temperature (TF) (1600-1900 °C) at a deposition rate of 8-12 Å/s without using any hydrogen dilution. While the films deposited at low TF are amorphous in nature, those deposited at higher TF (≥ 1800 °C) contain nanocrystallites embedded in the amorphous network. The optical band gap (E04) of the films (~ 1.89-1.99 eV) is slightly higher 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.