Photoemission study of Zn1-xCoxO as a possible DMS

We report a photoemission spectroscopy (PES) and X-ray absorption spectroscopy (XAS) study for bulk Zn1-xCoxO samples (x = 0 and 0.1). Both the Co 2p XAS and the Co 2p core-level PES spectra show that the doped Co ions in Zn1-xCoxO are in the divalent Co2+ (d(7)) states under the tetrahedral symmetry. A Co 2p --> 3d resonant photoemission spectroscopy measurement shows that the Co 3d states lie near the top of the O 2p valence band. This work suggests that the doped Co ions in Zn1-xCoxO substitute properly for the Zn sites with Co2+ valence states. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.