MONTE-CARLO SIMULATION OF ELECTRON-TRANSPORT IN MERCURY CADMIUM TELLURIDE

We derive expressions for electron scattering rates in mercury cadmium telluride accounting for correct wave functions in narrow-band-gap materials. These scattering rates differ slightly from the rates obtained from standard expressions for wide-band-gap materials. The difference is related to spin-flip processes and has a relatively small effect on the transport properties. However, it is very important for spin-orientation phenomena. Monte Carlo simulations have been performed to investigate the mobility and steady state velocity-field characteristics of electron transport in mercury cadmium telluride with x = 0.205 at 77 K. The simulations include scattering by polar optical phonons, ionized impurities, and alloy scattering. The Pauli exclusion principle as well as the dependence of the screening length on the distribution function have been accounted for. The simulations show that the screening length increases with increasing electric field with this dependence being the strongest for low carrier concentrations. For n = 5.4 x 10(15) cm-3, the inclusion of the Pauli exclusion principle and varying screening length reduces the electron velocity by 5% to 10% depending on the electric field. Velocity-field curves are in good agreement with experimental data up to the electric field where the impact ionization becomes important. We have also calculated the dependence of low-field mobility on the electron concentration, which shows reasonable agreement with experimental data.