<p>The computer program developed by T.B. Remple for the analysis of PiN photodiodes has been modified to handle Schottky barrier cases. The fundamental physics involved in the original model is summarized and the theories for a metal-semiconductor interface are presented. The boundary values for n, p, and ψ are then defined in such a way that ψ (x) would be in agreement with the thermionic-diffusion theory. An equivalent circuit approach is used to determine the RC response of the photodetector. While the modified version of the computer model provides very detailed analysis of the device, it is also very expensive to run. A simplified model is therefore employed for the design process. The objective is to design an Au-nGe photodiode with a risetime less than 50 psecs. The set of optimum design parameters obtained with the simplified model is then taken as the input to the modified version of Remple's program for further analysis. The theoretical risetime of the optimum design is found to be about 45 psecs.</p> / Thesis / Master of Engineering (ME)