Impact ionization in semiconductors: Effects of high electric fields and high scattering rates

Abstract

We present a theory of impact ionization in semiconductors that expands an earlier theory of Kane and includes the effects of high electric fields and high scattering rates on the electron-electron collision process. We show that their combined effect, i.e., the intracollisional field effect and collision broadening, leads to a softening of the threshold energy for impact ionization and a marked increase in the anisotropy of the ionization rate with respect to the direction of the electric field.