Impact ionization rate and high-field transport in ZnS with nonlocal band structure

The impact ionization rate in ZnS is calculated using a nonlocal empirical pseudopotential band structure and compared to previous results using a local calculation. The two resulting rates are then compared and simple fit formulas are presented. These are included in an ensemble Monte Carlo simulation of electron transport in bulk ZnS. The calculated impact ionization rate is then compared to experimental impact ionization coefficient data; reasonable agreement between the experimental data and the calculated impact ionization rate is obtained with an appropriate choice of optical deformation potentials. (C) 1996 American Institute of Physics.