Abstract
The purpose of this thesis is to discuss the geometry of reactor using Pla sma Enhanced Chemical Vapor Deposition (PECVD) and to discuss the underl ying principle of growing large area a:Si:H film. Then the reactor was used to deposit the Position Sensitive Detector (PSD). This PECVD system was b uilt by HELEX using Solarex's chamber. In our experiment it was found that the primary factor to affect the uniformity of large area a:Si:H film w as the gas flow distribution. In order to produce uniform gas flow dist ribution in the reactor, special design to set showerhead could solve i n problem. In the thesis we deposited the 125mm*125mm a-Si:H film wit h uniformity of 5% successfully.To deposit a-Si:H film by the PECVD system, it was shown that using rf generator of 27MHz, the deposition rate was greater than that of the conventional PECVD with 13.56MHz. The relationship between deposition rate and the argon d ilution ratio was also investigated.The structure of PSD is a PIN type. The ke y factor for the device sensitivity is the thickness of the I layer. For an I layer thickness of 10000A, the device photo-to-dark current rat io and rectification ratio was larger than those with I layer thickness of 5000A. Under 1000 lux illumination, the photo-to-dark current ratio of the device with I layer (10000A) at the bias of -0.5V, and 0V was 10000, and 3000, respectively, and the photo current at zero bias w as 2 uA. The rectification ratio was 1000. We also found that a thicker p layer was helpful to enhance the device performance.