Ab initio impact ionization rate in GaAs, GaN, and ZnS -: art. no. 085201

We have performed extensive ab initio band structure calculations within density functional theory using an exact exchange formalism with a local density approximation for correlations. The wave-vector-dependent impact ionization rate is determined for GaAs, GaN, and ZnS. A strong asymmetry of the microscopic scattering rate as well as a pronounced influence of the band structure is found. We present also energy-averaged impact ionization rates which can be used in ensemble Monte Carlo simulations of high-field electron transport in these materials.