Regulating effect of SiO2 interlayer on optical properties of ZnO thin films

ZnO/SiO2 nanocomposite films with periodic structure were prepared by electron beam evaporation technique. Regulating effect of SiO2 interlayer with various thicknesses on the optical properties of ZnO/SiO2 thin films was investigated deeply. The analyses of X-ray diffraction show that the ZnO layers in ZnO/SiO2 nanocomposite films have a wurtzite structure and are preferentially oriented along the c-axis while the SiO2 layers are amorphous. The scanning electron microscope images display that the ZnO layers are composed of columnar grains and the thicknesses of ZnO and SiO2 layers are all very uniform. The SiO2 interlayer presents a significant modulation effect on the optical properties of ZnO thin films, which is reflected in the following two aspects: (1) the transmittance of ZnO/SiO2 nanocomposite films is increased; (2) the photoluminescence (PL) of ZnO/SiO2 nanocomposite films is largely enhanced compared with that of pure ZnO thin films. The ZnO/SiO2 nanocomposite films have potential applications in light-emitting devices and flat panel displays.