Combined optical and electric simulation of metal-semiconductor-metal photodetectors

The combined optical and electric simulation of a metal-semiconductor-metal (MSM) photodetector is presented. The generalised multipole technique (GMT) for rigorous modelling of the light propagation is combined with electric device simulation methods based on a drift-diffusion charge carrier transport model. Different optical designs are compared with respect to the detector performance that can be achieved. It is demonstrated that the use of incoupling gratings can significantly increase the detector efficiency, compared to designs using antireflective layers. Numerical experiments carried out for illumination under varying angles of incidence also show that not only the amount of light that reaches the semiconducting substrate but also the exact spatial intensity distribution have non-negligible effects on the detector efficiency and response times. This in turn proves the necessity of rigorous optical simulation