Microscopic theory of high-field miniband transport in semiconductor superlattices

Abstract

A quantum theory of high-field miniband transport in semiconductor superlattices is developed that is applicable in the electric field range where negative differential conductance appears. The lateral electron distribution function is determined from a quantum kinetic equation, in which intracollisional field effects are included. Scattering on polar optical phonons is taken into account. Unlike the Boltzmann equation approach, our theory reproduces the experimentally detected temperature dependance of the current in both the hopping and band transport regimes. Numerical and analytical results show that at low temperatures the lateral electron distribution function strongly deviates from its equilibrium expression and exhibits sharp edges. For a superlattice with a narrow miniband the existence of electron-phonon resonance effects is predicted. The associated resonant-type current anomalies depend strongly on the temperature and are most pronounced at low temperatures.