Analytic Boltzmann equation approach for negative differential mobility in two-valley semiconductors

Abstract
We present results for the negative differential mobility and the distribution function in GaAs and InP for electric fields less than 40 kV/cm based on the analytic solution of the Boltzmann equation for a model with two valleys and three relaxation times. Using the measured low field mobility, lower valley mass, and valley separation energy Δ while adjusting three upper valley parameters, we obtain good agreement with the experimental velocity-field curves. The distribution function in the lower valley shows structure at energies ≊Δ due to the intervalley scattering.