The electronic structure of defect chalcopyrite CdGa2Se4 as determined from first principles calculations and X-ray spectroscopy studies

The total and partial densities of states of all components of CdGa2Se4 are calculated using the modified ab initio augmented plane wave (APW) method implemented in the WIEN2k software package. The results of the APW calculations indicate that in the CdGa2Se4 compound, the Sep states are the main contributions to the valence band, and their contribution is maximum at the top of the valence band, meanwhile at the bottom of the conduction band the contributions of the Gas* states dominate. According to the theoretical APW-calculations, the Cdd and Gap electronic states also contribute sufficiently to the valence band (mostly at the bottom and at the top of the band respectively) in CdGa2Se4. The joint alignment of CdL beta(2,15), GaK beta(2) and SeK beta(2) X-ray emission bands and of the X-ray photoelectron spectrum of the valence electrons obtained for the CdGa2Se4 single crystal, in a common energy scale, shows good agreement of the obtained theoretical and experimental data referring to the characteristic properties of the electronic structure of the CdGa2Se4 compound.