Deposition of amorphous and microcrystalline silicon using a graphite filament in the hot wire chemical vapor deposition technique

The use of a graphite filament in the "hot wire" chemical vapor deposition technique is demonstrated to produce "state-of-the-art" intrinsic and doped (p- and n-) amorphous silicon (a-Si:H) material and microcrystalline silicon (muc-Si) materials. Preliminary p-i-n type solar cells have led to a conversion efficiency of > 8.5%. The filament is found to be rugged and remains intact even after deposition of similar to 500 mum in thickness. This is in contrast to the use of conventional filament materials, such as W or Ta, whose longevity is limited to less than a few microns of deposition. Unlike the case of a Ta filament, the deposition rate remains constant with the use of a graphite filament. (C) 2001 American Vacuum Society.