[Structure and luminescence properties of ZnO films prepared by RF magnetron sputtering]

ZnO thin films with c-axis preferred orientation were prepared on glass substrates by radio frequency co-reactive magnetron sputtering technique, and the effect of the substrate temperature on the microstructure and the luminescence properties of the ZnO thin films was studied by X-ray diffractometry (XRD), scanning probe microscopy(SPM)and fluorescence spectrophotometer. The XRD patterns of the four ZnO samples prepared at different substrate temperatures were measured by XRD. figure which embodied the relation of full wave at half maximum (FWHM) and grain size of the four samples as a function of substrate temperatures was given out, too. It was concluded that the crystallization of the samples was promoted by appropriate substrate temperatures, the results consist with the AFM microscopic photos of the two samples. In addition, the photoluminescence (PL) spectra of the four samples were measured at room temperature. Violet peak located at about 400 nm, blue peak located at 446 nm and green peak located at about 502 nm were observed from the PL spectra of the four samples. With the rise of the growth temperature, the intensity of the violet peak and the blue peak increased sharply, and the intensity of green peak increased at the same time. It was concluded that the violet peak may correspond to the exciton emission, the blue peak was mainly attributed to the interstitial Zinc (Zn(i)) and the green emission peak must be related to the deep level defects of oxygen (Vo) in the crystal of ZnO films. Absorption property of the samples were researched by UV spectrophotometer, and the absorption spectrum of the film deposited at 150 degrees C and the (alpha h nu)2 versus h nu of the ZnO thin film were given. From the absorption spectrum, it could be observed that the spectroscopic data in UV region showed split peak and shoulder peak. With analysis of the absorption spectrum of the sample deposited at 150 degrees C, it was proved that our analysis of the photoluminescence mechanism was reasonable.