Effects of surface recombination on carrier distributions and device characteristics

Abstract

We calculate the effects of surface recombination on carrier distributions and device characteristics. The conventional approach assumes a constant surface recombination velocity in the calculation of the surface recombination current and carrier distributions. In this paper, we use the Shockley–Reed–Hall recombination mechanism to calculate the surface recombination rate without resorting to the use of a surface recombination velocity. The current continuity equation and Poisson’s equation are solved simultaneously for the carrier distributions, current density, and electric field in the bulk. The effects of surface recombination and surface charged states are included explicitly in the boundary conditions and charge neutrality equation. As a result of the inclusion of the surface charged states in the calculation, acceptor, donor, and compensating surface trap states can easily be included in our model. We calculate the influence of surface recombination on the performance of ridge-type devices and show that appropriate surface delta doping can be used to effectively reduce the surface recombination current for an uncompensated surface. We also compare our results to those obtained from a simple model which is based on a constant surface recombination velocity.