Transient impact ionization in bulk Si [MOS devices]

The generation rate, G_ii, due to impact ionization and the impact ionization coefficient α in bulk Si are calculated from carrier distribution functions, solving the k-space Boltzmann transport equation. G_ii and α are dependent on transients, and are not universal with respect to average energy, which facts originate in the different structures in k-space distribution function even at the same average energy. In such cases, the conventional relation of αJ (where J is the current density) fails to predict G_ii, so far as one takes α for the steady-state α _w defined as a function of average energy