Effect of TiO 2 buffer layer on the structural and optical properties of ZnO thin films deposited by E-beam evaporation and sol–gel method

Abstract

In this work, TiO 2 buffer layers were first deposited on Si substrates by electron beam evaporation, and then ZnO thin films were deposited on TiO 2 buffer layers by electron beam evaporation and a sol–gel method, respectively. The structural features and surface morphologies of these films were analyzed by X-ray diffraction (XRD) and a scanning probe microscope (SPM), respectively. The photoluminescence (PL) spectra were measured by a fluorophotometer. The analyses of the structures and surface morphologies showed that all the ZnO thin films were preferentially oriented along the c-axis perpendicular to the substrate surface; TiO 2 buffer layers increased the intensity of (0 0 2) diffraction peaks, made the grains denser and the surfaces of the films smoother. The photoluminescence spectra showed that TiO 2 buffer layers enhanced ultraviolet emissions and reduced visible emissions of the ZnO thin films to a large degree. All the results suggested that the use of TiO 2 buffer layers effectively improved the quality of ZnO thin films.