The ultraviolet emission line at 3.315eV was observed at 8K in ZnO polycrystalline films and investigated using temperature-dependent photoluminescence spectra and cathodoluminescence spatial imaging. The relative intensity of 3.315eV emission line depends strongly on growth and annealing conditions. The cathodoluminescence image showed that the 3.315eV emission localizes on the surface and ridge of ZnO grain. These results suggested that the 3.315eV emission attributes to Zn interstitials at the grain surface and ridge. This emission was stable in the range from 8K to 300K and contributed to the room temperature ultraviolet band.

Ultraviolet Luminescence Depending on Zn Interstitial in ZnO Polycrystalline Films. Xu, X.Q., Tian, K., Shi, Y.Y., Zhong, S., Zhang, W.Y., Fu, Z.X.: Chinese Physics Letters, 2008, 25[10], 3783-6