Valence band hybridization in N-rich GaN1-xAsx alloys -: art. no. 115214

We have used photomodulated transmission and optical absorption spectroscopies to measure the composition dependence of interband optical transitions in N-rich GaN1-xAsx alloys with x up to 0.06. The direct band gap gradually decreases as x increases. In the dilute x limit, the observed band gap approaches 2.8 eV; this limiting value is attributed to a transition between the As localized level, which has been previously observed in As-doped GaN at 0.6 eV above the valence band maximum in As-doped GaN, and the conduction band minimum. The structure of the valence band of GaN1-xAsx is explained by the hybridization of the localized As states with the extended valence band states of GaN matrix. The hybridization is directly confirmed by soft x-ray emission experiments. To describe the electronic structure of the GaN1-xAsx alloys in the entire composition range a linear interpolation is used to combine the effects of valence band hybridization in N-rich alloys with conduction band anticrossing in As-rich alloys.