Oxidation of Cu on ZnO(0001)-Zn: Angle-resolved photoelectron spectroscopy and low-energy electron diffraction study

Abstract

Angle-resolved photoelectron spectroscopy and low-energy electron diffraction measurements have been carried out to characterize the Cu oxide overlayer formed on the Zn-terminated ZnO(0001) surface. Deposition of Cu and subsequent oxidation lead to CU2O with (111) orientation. The Cu 2O(111) lattice structure is expanded so as to realize the epitaxial relationship to the underlying ZnO surface. The valence-band maximum of the Cu2O overlayer is found to be shifted to the lower-binding-energy side by ∼ 0.4 eV in comparison with that of bulk Cu2O, suggesting a stronger p-character of the overlayer than the bulk material. © 2008 The Surface Science Society of Japan.