Monte Carlo particle modeling of electron velocity overshoot effect in MSM photodiodes

We present a numerical study of metal-semiconductor-metal (MSM) photodiodes based on a planar structure composed of interdigitated Schottky contacts on top of a thin GaAs absorbing layer with lateral light input. A self-consistent ensemble Monte Carlo (MC) particle method with the Fourier transform of the calculated transient photocurrent is used to obtain the frequency dependent responsivity. It is shown that the MSM photodiodes can exhibit marked responsivity in terahertz range of signal frequencies even for contact spacing about few tenth of micrometer. The results of the MC simulation are discussed invoking proposed analytical model.