Volume and composition dependence of direct and indirect band gaps in ordered ternary III-V semiconductor compounds: A screened-exchange LDA study

Quasiparticle electronic band structures for ternary InGaAs and InGaSb systems, modeled by a luzonite structure, have been obtained using the screened-exchange local-density approximation approach. We focus our attention on energy transitions relevant for the electron-hole pair lifetime and, in particular, on the direct (E<(Gamma)over bar>-<(Gamma)over bar>) and lowest indirect (E<(Gamma)over bar>-(L) over bar) band gaps as a function of volume, common anionic species, and composition. All these degrees of freedom can be used to tune the transitions considered: as a first result, a large range of band gaps (almost 1 eV) can be obtained by varying the lattice constants within a few percent with respect to their equilibrium values. Moreover, the lowest indirect transition can be strongly reduced by replacing As with Sb. Finally, the composition dependence of these transitions shows that, due to symmetry properties of the potential in ternary luzonites, In-rich systems have the smallest indirect band gaps of all compounds investigated in this work.