ANALYTIC DISPERSION-RELATIONS NEAR THE GAMMA-POINT IN STRAINED ZINCBLENDE CRYSTALS

An eight-band k.p model of the electronic states near the GAMMA point of a strained zinc-blende semiconductor is renormalized using Lowdin perturbation theory. The renormalization leads to matrices of reduced dimensionality, 2x2, 4x4, and 2x2, for the conduction, light- and heavy-hole, and spin-orbit split-off bands, respectively. The reduced dimensionality of these matrices allows us to obtain analytic dispersion relations in the presence of small but arbitrary strains. Comparison of the analytic dispersion relations is made to those obtained by numerically diagonalizing the eight-band model for the case of biaxially strained and unstrained GaAs.