Strain compensation in lattice mismatched short-period superlattices

The electronic properties of [001] (A1As)n-(A1Sb)n short-period strained-layer-superlattices (SPSLS) lattice matched to InP, for n ≤ 4, have been calculated with a first-principles self-consistent pseudopotential method. The layer dependence of the interplanar 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 A1As0.5Sb0.5 represented 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. © 1998 Academic Press Limited.