The effects of oxygen partial pressure and substrate temperature on the structural and optical properties of ZnO films

ZnO were deposited on sapphire and silicon substrates by RF magnetron sputtering from a metallic zinc target. The structural and optical propertied of ZnO films were studied by X-ray diffraction, and UV-VIS-NIR scanning spectrophotometer. XRD measurements show ZnO films had a preferential orientation along the c-axis. Only one peak, (002) phase, appears on the diffraction spectra. The transmittance spectra indicate that ZnO films possessed a transmittance of about 80% in the visible region and a sharp absorption edge at wavelength of about 390nm. The refractive index n and the extinction coefficient k are all sensitive to the oxygen partial pressure and the substrate temperature. Furthermore, based on the ideal five layers symmetrical waveguide films, the relationships of the loss and the thickness of the waveguide layer and the buffer layer were analyzed using ZnO as waveguide layer and SiO2 as buffer layer.