EFFECT OF DEPOSITION TEMPERATURE ON THE STRUCTURAL AND ELECTRICAL-PROPERTIES OF LASER-CRYSTALLIZED HYDROGENATED AMORPHOUS-SILICON FILMS

The deposition temperature of hydrogenated amorphous silicon films dep osited by de glow discharge was found to affect the crystallinity, hyd rogen content, and silicon-hydrogen bonding after laser crystallizatio n of the film. This in turn affected the electrical properties of the crystallized film. The crystallinity of the film after laser annealing was always higher than that of the corresponding furnace-crystallized films, for the same deposition temperature, and it increased with dec reasing deposition temperature, similar to that observed in furnace cr ystallized films (650 degrees C, 30 h). However, the dark and photocon ductivity, photoresponse (defined as the ratio of photo to dark conduc tivity), and the carrier diffusion length increased with increasing de position temperature (150-350 degrees C). This was due to both an incr ease in hydrogen content and the SiH and SiH2 bonding, as shown by evo lved gas analysis and infrared spectroscopy. Carrier transport measure ments indicated that the dominant transport mechanism changed from loc alized hopping to extended state transport with increasing deposition temperature for the laser-crystallized films. (C) 1996 American Instit ute of Physics.