Influences of substrate temperature on the crystalline characteristics and optical properties for ZnO films deposited on freestanding thick diamond films

ZnO thin films were prepared on the smooth nucleation surfaces of freestanding CVD thick diamond films by reactive radio-frequency magnetron sputtering. With the increase of the substrate temperature, the growth and optical properties of the ZnO films were characterized experimentally by X-ray diffraction, room temperature photoluminescence spectra, and electron probe microanalysis(EPMA) and Hall measurements. The SEM results indicate that the ZnO film at the substrate temperature of 600°C is of the lowest roughness. The PL spectrum shows that the sample at the substrate temperature of 750°C has the best optical property, which is near the stoichiometry of ZnO characterized by EPMA. The Hall effect measurement shows that the samples have high resistivity, which can meet the requirements of SAW devices.