Electronic structure of BxGa1−xAs alloys using hybrid functionals

Abstract

We present electronic band structure calculations of BxGa1−xAs alloys over the full composition range using HSE06 hybrid functionals. We find that at low boron percentages, the direct bandgap decreases slightly and then increases toward the large minimum direct gap of BAs as more boron is added. Our results show that the effect of isolated boron atoms on the bandgap is small (<5%) at concentrations below 13%. We estimate that BGaAs transitions from the direct to indirect bandgap at around 18% boron content. We calculate the electron effective masses in the direct bandgap region and investigate the effect of B-B pairs in nearest-neighbor group III sites on the bandgap, conduction band dispersion, and total free energy. We find that the lattice constant of BGaAs follows Vegard's law and estimate that the boron concentration required to lattice match BGaAs to silicon is outside the direct gap regime.