Photoluminescence and XPS Characterization of Zinc Oxide Doped with Anions

The bromide and sulfur co-doped ZnO phosphors with highly efficient green luminescent emission are prepared by calcining ZnS in air atmosphere at 800℃ with NH4Br as flux.The origin of green emission is investigated by means of XPS technique.It is found that doping with S and Br in ZnO results in the formation of oxygen vacancy V′O and zinc hole V′Zn,and the green emission band could be ascribed to a transition of a photogenerated electron from the localized defect centers(V′O) to a deeply trapped hole(V′Zn) within the band gap.