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

Abstract ZnO/TiO 2 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 TiO 2 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 nm, violet peak at 423 nm and weak green luminescence at 544 nm is observed in the ZnO/TiO 2 thin film. The violet luminescence emission at 423 nm is attributed to the interface trap in the ZnO film grain boundaries.