Empirical tight-binding model for the electronic structure of dilute GaNAs alloys

We present an empirical tight-binding (TB) model for the electronic structure of ${\mathrm{GaN}}_{x}{\mathrm{As}}_{1\ensuremath{-}x}$ with nitrogen content $x<5%,$ over the entire Brillouin zone. The model upgrades existing TB schemes, introducing an additional s orbital to account for the N-induced change of conduction-band states. The resulting band structure is analyzed using an ${\mathrm{sp}}^{3}{d}^{5}{s}^{*}$ TB parametrization and compared to experimental and other theoretical data. The model reproduces the results of the band anticrossing model at the \ensuremath{\Gamma} point of the Brillouin zone, and the dependence of the X and L band-edge states on the N concentration is in good agreement with experimental data. The model is readily applicable to electronic structure calculations of other III-N-V compounds and heterostructures.