Analysis of transfer function of metal-semiconductor-metal photodetector equivalent circuit

The response of GaAs metal-semiconductor-metal photodetectors (MSM-PD) is simulated using a phenomenological model of transport equations, which takes into account the electron intervalley transfer. Calculations are performed for intrinsic devices with 1 mu m and 0.5 mu m interdigital spacing with the corresponding equivalent (parasitic) circuit of the photodetector. It is pointed out that parasitic effects may induce a significant distortion, a delay of intrinsic response, and increase bit error rate. Analysis of the equivalent or parasitic circuit of the MSM-PD transfer function shows that the distortion and delay of the intrinsic signal can be minimized by choosing the optimal photodetector capacitance. (C) 1997 American Institute of Physics.