QUASI-CLASSICAL DESCRIBING OF THE BLOCH OSCILLATION IN A SUPERLATTICEBY FOKKER-PLANCK EQUATION

A theoretical study of Bloch electron transport in a superlattice mini band driven by an electric field parallel to the growth axis is carrie d out, by Fokker-Planck equation (FPE) in momentum space with the aver aged momentum relaxation time (tau) approximation. Steady-state drift- velocity/field characteristics exhibit the expected maximum followed b y negative differential conductivity (NDC), and then followed by drift -velocity oscillation when tau or electric field is large. The oscilla tion frequency is an increasing function of tau, and when tau --> infi nity, the limit of the oscillation frequency is the Bloch frequency as expected.