X‐ray spectroscopic investigation of forbidden direct transitions in CuGaO₂ and CuInO₂

Abstract

Abstract We studied experimentally the local partial density of electronic states (LPDOS) in the conduction band (CB) and in the valence band (VB) of CuGaO 2 and CuInO 2 by means of X‐ray absorption spectroscopy (XAS) and X‐ray emission spectroscopy (XES). The edges of both the CB and VB are found to be the copper s‐ and/or d‐states. Therefore, direct transitions between the band edges in these materials should be forbidden by symmetry selection rules. The crystal phases in the samples were identified as having delafossite structure, determined by X‐ray powder diffraction (XRD). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)