Accurate modeling of energy-dependent impact ionization rate for hydrodynamic simulators of semiconductor devices

Abstract

Proposes an accurate nonlocal model describing the impact ionization rate in semiconductor devices in terms of the carrier mean energy. The model is developed from the general set of hydrodynamic equations (HDEs) without presuming any form a priori for the carrier distribution function. A fundamental feature of the present model is that it takes into account the band structure effect on the carrier generation rate through the carrier-energy relaxation time. In order to confirm the validity of the model, it is compared with the famous empirical and analytical models. In contrary to the previous energy-dependent models, the present one does not underestimate the generation rate by impact ionization at high fields. So, it can be used for better predictions of the avalanche breakdown voltage and avalanche injection currents in semiconductor devices.