Co-emission of UV, violet and green photoluminescence of ZnO/TiO2 thin film
Linxing Shia, , , Hua Shenb, Liyong Jianga and Xiangyin Lia
aDepartment of Physics, Nanjing University of Science and Technology, Nanjing 210094, PR China bInstitute of Electronic Engineering and Photo-electric Technology, Nanjing University of Science and Technology, Nanjing 210094, PR China Received 20 January 2007; accepted 4 March 2007. Available online 14 March 2007.
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 nm, 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.
Keywords: ZnO; TiO2 buffer layer; Co-emission; Luminescence; Thin films