An assessment of approximate nonstationary charge transport models used for GaAs device modeling

A study of the utility of deterministic nonstationary models of charge transport in GaAs is presented. The models considered include energy and momentum conserving, energy conserving, and electron-temperature formulations. Predictions of the models are compared with results calculated using a more detailed Monte Carlo-based scattering-process-level simulation. The basis of the comparison is calculated trajectories in velocity-energy-field space for a range of time-dependent electric field forcing functions. All the nonstationary transport models considered are found to be in reasonable agreement with Monte Carlo results for all but the most extreme circumstances considered and to be greatly superior to the drift-diffusion approximation. Strengths, weaknesses, and applicability of individual models are discussed