Co-emission of UV violet and green photoluminescence of ZnO/TiO2 thin film

ZnO/TiO2 thin films were fabricated on quartz glass substrates by E-beam evaporation. The structural and optical properties were investigated by X-ray diffraction (XRD), Raman spectra, optical transmittance and photoluminescence. XRD analysis indicates that the TiO2 buffer layer can increase the preferential orientation along the (002) plane of the ZnO film. PL measurements suggest that co-emission of strong UV peak at 378 run, violet peak at 423 nm and weak green luminescence at 544 nm is observed in the ZnO/TiO2 thin film. The violet luminescence emission at 423 nm is attributed to the interface trap in the ZnO film grain boundaries. (c) 2007 Elsevier B.V All rights reserved.