The effects of r.f. power and substrate temperature on the properties of ZnO films

ZnO thin films were prepared by r.f. magnetron sputtering from a zinc oxide target. The effects of r.f. power and substrate temperature on the properties of ZnO films were studied. The composition of ZnO films was analyzed by X-ray photoemission spectroscopy. The Zn atomic composition in the films was higher than the O atomic composition at any r.f. power and growth temperature conditions. This behavior might be explained by the preferential sputtering of zinc atoms rather than oxygen atoms in the ceramic target. In this study, ZnO films with epitaxial grain growth had a preferred (0 0 2) orientation. The crystallographic orientation and the piezoelectric properties of ZnO films were influenced by the sputtering parameters. A good condition exists for making the c-axis oriented films in the range of deposition rate and substrate temperature under the experimental conditions in this study. ZnO films showed different surface morphologies and surface roughness under different deposition conditions. ZnO films were transparent in the visible region, but had obvious absorption in the UV region. There were no obvious changes in the optical properties of ZnO films by varying the r.f. power and substrate temperature in this study. The phase velocity in this study was relatively higher at the optimal r.f. power and substrate temperature.