Electronic band structure of superlattices under a uniform electric field and Wannier-Stark effect

The electronic band structures of GaAs/(GaAl)As superlattices under a uniform electric field along the growth axis are calculated on the basis of a microscopic tight-binding (TB) description. Finite sets of quantum wells are considered in order to apply the TB method to a system without translational symmetry. The main effect of the electric field appears as diagonal elements of the TB matrix, resulting in modulation of miniband dispersion and localization of wavefunctions (Wannier-Stark effect). The calculated results are found to be in good agreement with the experimental observation by electroreflectance measurements.