Effect of the optical power and active layer thickness on the photocurrent in metal-semiconductor-metal detectors

The dependence of the photocurrent, in a planar metal-semiconductor-metal photodetectors (MSM), on active layer thickness and incident optical power is investigated using a two-dimensional drift-diffusion model. The model numerically solves the basic semiconductor equations using appropriate boundary conditions at the Schottky contacts. The calculated results show good agreement with experimental results reported in the literature. The current-voltage characteristics show an offset voltage of about 0.2V that depends on the incident optical power. The results also show that the photocurrent increases with active layer thickness but saturates beyond few microns.