MICROSCOPIC THEORY OF HIGH-FIELD MINIBAND TRANSPORT IN SEMICONDUCTOR SUPERLATTICES

A quantum theory of high-field miniband transport in semiconductor sup erlattices 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 held effects are included. Scattering on pol ar optical phonons is taken into account. Unlike the Boltzmann equatio n approach, our theory reproduces the experimentally detected temperat ure dependence of the current in both the hopping and band transport r egimes. 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 w ith a narrow miniband the existence of electro-phonon resonance effect s is predicted. The associated resonant-type current anomalies depend strongly on temperature and are most pronounced at low temperatures.