LAUSR

Abstract In this paper the electronic structure of the valence states in CuInSe2, CuGaSe2 and CuIn0.5Ga0.5Se2 is considered in details in a wide energy range up to 20 eV from the Fermi level. Examining the electronic structure within the LDA + U method we focus on the deep, occupied 4d indium and 3d gallium electronic states. The calculated electronic structure is compared with high-resolution experimental photoemission (PE) spectra measured for high structural quality single crystals of these compounds at a photon energy of 600 eV. The comparison helped us to understand the nature of the observed spectral features associated with electronic states near the Fermi level. The calculated energies of the Ga-3d and In-4d states exhibited a good agreement with the experimentally determined spectral positions of these states in the PE spectra. The significance of these states for the application in quantum optics is discussed.