Investigation on visible emission of ZnO films deposited on copper nitride substrates

ZnO films with different oxygen gas flow rate are deposited on copper nitride substrates by radio frequency magnetron sputtering. All samples are annealed in vacuum at 350 °C for 1h. Results indicates that Cu3N diffraction phase is observed in the XRD pattern of copper nitride substrates. As ZnO layer is deposited on copper nitride substrates, Cu3N diffraction peak disappears. PL spectra of all samples shows two blue emission peaks and a green emission. Under the unbalanced stoichiometric ratio, the blue peaks are enhanced. Especially, at a low oxygen gas flow rate of 5:25 sccm, two blue peak intensity reach maximum. In this case, there are overabundance Zn atoms due to a poor oxygen atmosphere. Both interstitial Zn and various substitution defects will appear in the deposited films, thus causing the intensity increment of visible emission peaks.