Theory of electronic and optical properties of bulk AlSb and InAs and InAs/AlSb superlattices

Abstract

An empirical tight-binding model with an orthogonal ${\mathrm{sp}}^{3}$ set of orbitals, interactions up to second neighbor, and spin-orbit coupling is used to describe the electronic and optical properties of bulk InAs and AlSb as well as InAs/AlSb superlattices. The tight-binding parameters required for the model are obtained by fitting existing band structures for bulk materials. It is found that with the evaluated tight-binding parameters the model describes very accurately the band structure and the optical properties of the bulk materials. Then the model is used in order to investigate the electronic and optical properties of InAs/AlSb superlattices. It is shown that interface states located in the InSb-like interface quantum wells produce a narrow upper valence band. The effective masses and the variation of the energy gap with interface structure and lattice periodicity are also examined. Additionally the optical functions for the superlattice are calculated, and from the second derivative of ${\ensuremath{\varepsilon}}_{2}$ the critical points are obtained. Finally the optical anisotropy in the superlattice plane is investigated.