Abstract
Using Plasma-Enhanced Chemical Vapor Deposition (PECVD) system to deposit a-Si:H p-i-n photo diode or photovoltaic solar cell is very common. In order to manufacture higher performance photo diode, we first analyze the optical and electrical properties of the most important light-absorption layer – intrinsic hydrogenated amorphous silicon film. The photo conductivity to dark conductivity ratio of i-layer ( ) is about 105. And because the a-Si:H p-i-n photo diode is deposited directly in a single PECVD chamber, so the contamination to i-layer by dopant atoms will be a critical issue. But we had raise up the photo-to-dark current ratio of a-Si:H p-i-n photo diode to 107 ~ 108 by the specific chamber purge process. And the external quantum efficiency η can reach more than 70% for 550nm light. Because of the high performance of the a-Si:H p-i-n photo diode, this makes it possible for the use in the medical application.