Giant and Composition-Dependent Optical Bowing Coefficient in GaAsN Alloys

This is the authors' abstract. We don't add key points for this paper.

Using first-principles supercell calculations we find a giant (7--16 eV) and composition-dependent optical bowing coefficient in GaAs_1-xNₓ alloys. We show that both effects are due to the formation in the alloy of spatially separated and sharply localized band edge states. Our analysis suggests that in semiconductor alloys band gap variation as a function of x can be divided into two regions: (i) a bandlike region where the bowing coefficient is relatively small and nearly constant, and (ii) an impuritylike region where the bowing coefficient is relatively larger and composition dependent. For GaAs_1-xNₓ the impuritylike behavior persists even for concentrated alloys.