Strain compensation in lattice mismatched short-period superlattices

Abstract

The electronic properties of [001] (AlAs)n–(AlSb)nshort-period strained-layer-superlattices (SPSLS) lattice matched to InP, forn⩽ 4, have been calculated with a first-principles self-consistent pseudopotential method. The layer dependence of the inter\\-planar relaxations, direct and indirect band gaps, and spin–orbit and valence band strain splittings are studied. Evolution of the superlattice states from the bulk constituents is discussed in terms of wavefunction mixing and band repulsion due to zone-folding. The band structures of the SPSLSs are compared with a disordered alloy of AlAs0.5Sb0.5represented by the special quasirandom structure. We find that continuum models of the total valence band splitting (strain and spin–orbit) do not accurately represent the electronic structure of lattice mismatched SPSLS, due to strong mixing of the heavy- and light-hole states across the interface.