Impact-ionization coefficient in silicon at high fields— a parametric approach

Abstract

The impact-ionization coefficient α n at high fields is derived in terms of the electric field E and lattice temperature T L , without introducing a priori relations among the parameters. An asymptotic analysis leads to simplifications that validate closed-form expressions of α n . The role of the relaxation times in determining the slope of α n (E) is discussed, along with the meaning of the critical field.

Hydrodynamic device simulation of 200 GHz SiGe heterojunction bipolar transistors

“…The role of the momentum and energy relaxation times in the impact ionization coefficient at high fields has been recently discussed using a parametric expression for electron impact ionization rate [10]. In [11] the characteristic of impact ionization for uniaxially/biaxially strained Si and biaxially strained SiGe were explored.…”