MINIBAND BLOCH CONDUCTION IN SEMICONDUCTOR SUPERLATTICES

Linear and nonlinear characteristics of superlattice perpendicular conduction are examined from a balance-equation theory recently developed for miniband transport [Lei, Horing, and Cui, Phys. Rev. Lett. 66, 3277 (1991)]. Analytical expressions are given for linear mobilities due to impurity and due to optic-phonon scatterings. Attention is focused on the temperature dependence of low-field miniband mobility and the behavior of drift velocity versus electric field, derived from the balance-equation theory, as well as from Esaki-Tsu and Boltzmann theories. Good qualitative agreements are obtained in comparison with experiments, but more accurate measurements are needed to appreciate the differences between these two types of theories.