Position dependent photocurrent intensity of MSM photodetectors

It was found experimentally that the photocurrent intensity in a Metal-Semiconductor-Metal (MSM) structure has a strong dependence on the position of the incident laser beam; however, there is no satisfactory explanation of this phenomenon. We simulated this process with device simulator ATLAS, and the result agrees with experiment pretty well. We also investigated various factors such as material property and external bias voltage that affect the current density, and found that the photocurrent changed significantly with these parameters.