Nitrogen local electronic structure in Ga(In)AsN alloys by soft-X-ray absorption and emission: Implications for optical properties

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Soft-X-ray emission and absorption spectroscopies with their elemental specificity are used to determine the local electronic structure of N atoms in Ga(In)AsN diluted semiconductor alloys (N concentrations about 3%) in view of applications of such materials in optoelectronics. Deviations of the N local electronic structure in Ga(In)AsN from the crystalline state in GaN are dramatic in both valence and conduction bands. In particular, a depletion of the valence band maximum in the N local charge, taking place at the N impurities, appears as one of the fundamental origins of reduced optical efficiency of Ga(In)AsN. Incorporation of In in large concentrations forms In-rich N local environments such as In4N whose the electronic structure evolves towards improved efficiency. Furthermore, a k-character of some valence and conduction states, despite the random alloy nature of Ga(In)AsN, manifests itself in resonant inelastic X-ray scattering.