Abstract
The effects of rf power and substrate temperature on the crystal quality of ZnO thin films deposited on sapphire (001) substrates by rf magnetron sputtering are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and photoluminescence (PL) spectroscopy analyses. A ZnO thin film with the highest crystal quality is obtained by rf magnetron sputtering at a substrate temperature of 600°C and an rf power of 80 W. The crystal quality of the film is markedly improved by annealing. Excess rf power deteriorates the crystallinity and surface roughness of the film. PL spectroscopy analysis results confirm that rf magnetron sputtering yields ZnO films with a low density of crystallographic defects. Therefore, high-quality ZnO films can be obtained by optimizing the substrate temperature and rf power when using the rf magnetron sputtering technique and by annealing.