First principles modeling of high field transport in wide-band-gap materials

In the present work, we have theoretically investigated the electronic and transport properties of three wide-band-gap materials, ZnS, SrS, and GaN, u sing full-hand ensemble Monte Carlo (EMC) simulation. We show a suppression of the hole impact ionization rate for ZnS and SrS in particular, and GaN to a lesser extent, due to the narrowness of the upper valence bands. The r esulting impact ionization coefficient for electrons in ZnS simulated using the EMC with microscopically calculated phonon scattering rates is in good agreement with the re-interpreted data of Thompson and Alien (J. Phys. C: Solid State Phys. 20 (1987) L499). (C) 1999 Elsevier Science B.V. All right s reserved.