QUASI-PARTICLE CALCULATION OF THE ELECTRONIC BAND-STRUCTURE OF THE (INAS)1/(GAAS)1 SUPERLATTICE

We present a screened-exchange calculation of the one-electron excitations of the strained pseudoalloy (InAs)1/(GaAs)1 grown on an InP substrate. The model adopted was the local-density-functional and quasiparticle self-energy approximation with a statically screened local dielectric matrix and the spin-orbit interaction term evaluated within degenerated perturbation theory. The gap calculated with the room-temperature lattice constant is 0.66 eV. The calculations of the GaAs and InAs bulk materials, both unstrained and strained on the InP substrate, were also performed and give somewhat underestimated values for the zone-center gaps and an excellent agreement with experimental results for the tetragonal and spin-orbit splittings. The dispersion curves and the contour plots of the valence density as well as of the density of the first conduction states are also displayed. The behavior of the dispersion curves very close to the zone center was analyzed both for the strained bulk materials and the (InAs)1/(GaAs)1 superalloy, leading to some interesting features.