Impact ionization and high-field effects in wide-band-gap semiconductors

Abstract

Impact ionization is important for electron transport in wide-band-gap semiconductors at high electric fields. We consider a realistic band structure as well as high-field quantum corrections such as the intracollisional field effect in the calculation of the microscopic scattering rate. A pronounced softening of the impact ionization threshold is obtained. This field-dependent impact ionization rate is included within a full-band ensemble Monte Carlo simulation of high-field transport in ZnS. Although the impact ionization rate itself is strongly affected, little effect is observed on measurable quantities such as the impact ionization coefficient.