Effects of Chemical Treatment on the Luminescence of ZnO

The effects of chemical treatment on the luminescence of ZnO were investigated by cathodoluminescence. For this purpose, ZnO ceramics and O- and Zn-terminated faces of ZnO single crystals were studied. The samples were dipped in KOH and HCl solutions as well as pure H2O for 3 min. H2O and HCl treatments of ZnO ceramics can increase or decrease the initial ultraviolet (UV) intensity depending on the location examined, and induce an increase of the UV intensity under e-beam irradiation. HCl treatment of the Zn-face of ZnO single crystals slightly affects the surface morphology and the luminescence. HCl treatment of the O-face etches the surface to hexagonal pyramidal features. In addition, the initial UV intensity is always lower for the HCl-treated than for the untreated O-face, while the UV intensity increases at the beginning of e-beam irradiation. These results suggest that the UV intensity is influenced by the surface and bulk reactions of H+ with ZnO.