Effect of deposition temperature on the photoresponse of crystallized hydrogenated amorphous silicon films

The deposition temperature of hydrogenated amorphous silicon films deposited by dc glow discharge was found to affect the photoresponse (ratio of the photo to dark conductivity) after crystallization of the film. This effect depended on the crystallization technique. For crystallization by laser annealing, the photoresponse (0.15 - 1.5) increased with increasing deposition temperature (150 - 300 °C) due to the increase in SiH and SiH₂ bonding, as shown by infrared spectroscopy. For crystallization by furnace annealing (e.g. 650 °C, 50 h), the photoresponse (0.08 - 0) decreased with increasing deposition temperature (150 - 300 °C) due to the decrease in grain size and crystallinity as shown by x-ray diffraction; the complete loss in hydrogen during furnace annealing made the photoresponse low and the silicon-hydrogen bonding effect immaterial. Thus, laser crystallization at the highest deposition temperature gave the highest photoresponse.