Tagged-electron and Fick's diffusion coefficients from hot-electron velocity fluctuations in doped GaAs at 80K

The observed weak field dependence of electron mobility at moderate fields in Si-doped n-type GaAs at 80 K makes it possible to determine the electric field dependent Fick's diffusion coefficient of electrons from microwave noise temperature and mobility measurements even when the interelectron collisions cannot be neglected. It follows from Monte Carlo simulation that, contrary to mobility, microwave noise is quite sensitive to the intensity of interelectron collisions. The "tagged" electron diffusion coefficient given by the spectral density of one-electron velocity autocorrelation differs from Pick's diffusion coefficient because the history of the single electron cannot predict the characteristics of smoothing of gradients in the system of intercolliding electrons.