Physical models of ohmic contact for Monte Carlo device simulation

This paper investigates the problem of meddling ohmic contacts for Monte Carlo simulation of semiconductor devices. Several models are proposed with different velocity distributions for the injected carriers. The influence of each model on the device physics near the contact is discussed. As a prototype for this analysis we investigate the role of the ohmic contact on the electrical characteristics of a GaAs Schottky-barrier diode under forward-bias condition. To get accurate results from the simulations of this device, correct modelling of the ohmic contact is crucial. We have found that the best simulation of the carrier dynamics near the contact is achieved by using a velocity-weighted Maxwellian distribution for injecting the carriers, which provides hat profiles of the different magnitudes near the boundary and a zero voltage drop at the contact. in addition, an appropriate time and space algorithm for carrier injection must be applied.