ELECTRONIC-STRUCTURE OF STRAINED GAAS/GAP (001) SUPERLATTICES

GaAs and GaP have a 3.7% lattice mismatch. The resulting biaxial strains, when (001) superlattices are grown, have very substantial effects on the electronic states concerning level splittings, energy shifts, subband inversions, and orbital character. The electronic structure of (6,2), (6,4), and (6,6) superlattices is studied by means of an empirical tight-binding model in a way that identifies separately the effects of an initial band offset-here an empirical parameter-and those due to strains. A consistent picture is obtained in agreement with observed optical transitions.