PHOTOCURRENT MULTIPLICATION IN HYDROGENATED AMORPHOUS-SILICON P-I-N PHOTODIODE FILMS

The photocurrent multiplication of hydrogenated amorphous silicon p-i-n photodiodes was observed in photodiodes that were fabricated on a heavily doped n-type silicon substrate using a high-vacuum plasma enhanced chemical vapor deposition (PECVD) system. By using this improved PECVD system, the breakdown field of the photodiodes was changed from 3 x 10(5) V/cm to 1 X 10(6) V/cm. It seems that the reason for this increase of the breakdown field was a decrease of localized states in the forbidden gap that was produced by contaminants. The a-Si:H p-i-n photodiodes with low residual stress were fabricated on Si substrates, and the photocurrent multiplication was observed in these photodiodes. The wavelength dependence of incident light and the a-Si:H thickness dependence of intrinsic layer were found and these characteristics were explained by the avalanche multiplication of photogenerated electrons.