X-ray photoelectron spectroscopy of Zn0.98Cu0.02O thin film grown on ZnO seed layer by RF sputtering

We report the synthesis and electronic structure study of ZnCuO nanocrystalline thin film grown on ZnO seed layer by RE magnetron sputtering. X-ray diffraction (XRD) pattern reveals the single phase wurtzite structure preferentially grown along c-axis, while crystallite size using Debye Scherer's relation was calculated to be 10 nm. The scanning electron microscopy (SEM) depicts a columnar structure with a dense distribution of grains. X-ray photoelectron spectroscopy (XPS) of sputter-cleaned surface reveals a better stoichiometry and reduced oxygen vacancies in comparison to the as-deposited film. The Cu 2p core level spectrum ensures the Cu doping and suggests that Cu exists as Cu2+ and a mixture of Cu2+/Cu+ at the surface of as-deposited and sputter-cleaned film, respectively. (C) 2012 Elsevier B.V. All rights reserved.