Electronic structure of GaAs1-xNx alloy by soft-X-ray absorption and   emission: Origin of the reduced optical efficiency
  The local electronic structure of N atoms in a diluted GaAs1-xNx (x=3%) alloy, in view of applications in optoelectronics, is determined for the first time using soft-X-ray absorption (SXA) and emission (SXE). Deviations from crystalline GaN, in particular in the conduction band, are dramatic. Employing the orbital character and elemental specificity of the SXE/SXA spectroscopies, we identify a charge transfer from the N atoms at the valence band maximum, reducing the overlap with the wavefunction in conduction band minimum, as the main factor limiting the optical efficiency of GaAs1-xNx alloys. Moreover, a k-conserving process of resonant inelastic x-ray scattering involving the L1 derived valence and conduction states is discovered. 
V.N. Strocov, P.O. Nilsson, A. Augustsson, T. Schmitt, D.   Debowska-Nilsson, R. Claessen, A.Yu. Egorov, V.M. Ustinov, Zh.I....