High Speed Deposition of Amorphous Silicon Film by Atmospheric Pressure Plasma Chemical Vapor Deposition (3rd Report): Electrical and Optical Properties of a-Si Films Fabricated at Very High Deposition Rate

Electrical and optical properties of amorphous silicon (a-Si) films fabricated at very high deposition rate using an atmospheric pressure plasma CVD method with rotary electrode were evaluated for applying to the electric devices. As the results, it was found that a-Si films with this method have good properties such as high photo sensitivity (σph/σd-106 at deposition rate of 0.3μm/s). And the optical gap (Eopt; determined (αhv)1/3 versus hv plot) was about 1.5 - 1.6 eV which were similar to those of a-Si films fabricated by the conventional plasma CVD method at low pressure. With increasing the deposition rate, the Eopt decreased and the hydrogen content in the a-Si films increased, and this tendency was contrary to that of the general a-Si films. These results indicate that the structure of a-Si films with this method include much disorder configuration which narrowed the Eopt. However, enough hydrogen in the films terminated the dangling bonds and caused the reduction of defect density. In conclusion, it was thought that the atmospheric pressure plasma CVD method could fabricate the device grade a-Si film at very high deposition rate.