Synthesis and photoluminescence of (Co, Cu)-doped ZnO thin films

Abstract

Co, Cu single doped and co-doped ZnO thin films were fabricated on the glass substrate by means of sol-gel process. The influence of Co and Cu doping on the surface morphologies of ZnO films was investigated. X-ray diffraction shows that all the ZnO thin film samples are well oriented and the grain size of Cu-doped ZnO film is the largest. Strong blue double emission and weak green emission were observed in the photoluminescence spectra of all samples at room temperature and both long wavelength blue peak and green peak could be modulated by doping. The blue double peaks are caused by transition of electrons from the bottom of the conduction band to zinc vacancy or from the zinc interstitial to the top of the valence band. However, the green peak is highly relevant to the oxygen slip formed by doping.