Localized electronic states in coupled superlattices

Abstract

Theoretical investigation of the electronic structure of GaAs/AlAs superlattices coupled via an ${\mathrm{Al}}_{\mathrm{y}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{y}}$As spacer layer is presented. A direct matching procedure within an envelope-function approximation is used to derive the expressions for the energy and the corresponding wave function of localized electronic states appearing inside the minigaps. The transformation from a Tamm-like interface state to an above-barrier localized state is discussed. The density-of-states distributions inside the minibands are computed using the factorization and direct Green function methods. A possibility of the existence of a well-defined interface resonance in the lowest miniband is shown.