Monte Carlo calculation of diffusion coefficients in degenerate bulk GaAs

Standard Monte Carlo methods for calculating diffusivity fail when the degeneracy of the electron gas is important. We apply a recently proposed Monte Carlo procedure in order tot study diffusion coefficients in degenerate bulk GaAs at 77 K. Two sets of electrons are simulated, the first one representing the uniform 'background' electron density and the second one accounting for additional 'excess' electron concentration. The diffusion coefficients are calculated accounting for 'excess' electrons only. We compare the results obtained using this method with those obtained using the standard technique. We report diffusivity-field characteristics for several electron concentrations. Obtained zero-field values are in good agreement with those predicted by the Einstein relation. We found that, in the low-held region, diffusion coefficients evolve quite slowly with the electric field and the isotropy is conserved.