Influence of metallic coatings on the photoluminescence properties of ZnO nanowires

We report on low-temperature photoluminescence studies of ZnO nanowires coated with thin metallic films. For all analyzed metals (Al, In, Au, Ni, Cu), we find an increased relative intensity of the green deep-level emission. This is accompanied by a significant reduction of the relative intensity of the surface exciton band. The observed effects are most likely related to the formation of metal induced gap states in the surface region of the ZnO nanowires. A model for the band structure in the surface region of the metal-coated nanowires is proposed that successfully explains the changes in the photoluminescence spectra after the coating process. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim