Valence-band anticrossing in mismatched III-V semiconductor alloys

We show that the band gap bowing trends observed in III-V alloys containing dilute concentrations of Sb or Bi can be explained within the framework of the valence-band anticrossing model. Hybridization of the extended $p$-like states comprising the valence band of the host semiconductor with the close-lying localized $p$-like states of Sb or Bi leads to a nonlinear shift of the valence-band edge and a reduction of the band gap. The two alloys $\mathrm{Ga}{\mathrm{Sb}}_{x}{\mathrm{As}}_{1\ensuremath{-}x}$ and $\mathrm{Ga}{\mathrm{Bi}}_{x}{\mathrm{As}}_{1\ensuremath{-}x}$ are explored in detail, and the results are extrapolated to additional systems.