Tight-binding study of interface states in semiconductor heterojunctions

摘要

Localized interface states in abrupt semiconductor heterojunctions arestudied within a tight-binding model. The intention is to provide a microscopicfoundation for the results of similar studies which were based upon thetwo-band model within the envelope function approximation. In a two-dimensionaldescription, the tight-binding Hamiltonian is constructed such that theDirac-like bulk spectrum of the two-band model is recovered in the continuumlimit. Localized states in heterojunctions are shown to occur under conditionsequivalent to those of the two-band model. In particular, shallow interfacestates are identified in non-inverted junctions with intersecting bulkdispersion curves. As a specific example, the GaSb-AlSb heterojunction isconsidered. The matching conditions of the envelope function approximation areanalyzed within the tight-binding description.