Papers by Author: J.H. Gu

Abstract: Indium tin oxide (ITO) thin films were deposited by RF magnetron sputtering on glass substrates employing a sintered ceramic target. The influence of substrate temperature on the structural, compositional, optical and electrical properties of the thin films were investigated by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), spectrophotometer and four-point probes. All the ITO thin films show a polycrystalline indium oxide structure and have a preferred orientation along the (222) direction. The substrate temperature significantly affects the crystal structure and optoelectrical properties of the thin films. With the increment of substrate temperature, the electrical resistivity of the deposited films decreases, the crystallite dimension, optical bandgap and average transmittance in the visible region increase. The ITO thin film deposited at substrate temperature of 200 °C possesses the best synthetic optoelectrical properties, with the highest transmittance, the lowest resistivity and the highest figure of merit.

Abstract: Al-doped ZnO (ZnO:Al) thin films were deposited on glass substrates by rf magnetron sputtering technique. The effect of discharge power on the structural, optical and electrical characteristics of ZnO:Al films was investigated by X-ray diffraction (XRD), four-probe meter and optical transmission spectroscopy. The results show that the films are polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The highest figure of merit of 5.58×10-3 -1 is obtained from the film prepared at the discharge power of 200 W. The average optical transmittance in the visible range of the films is over 78.2%.

Abstract: Zinc oxide (ZnO) thin films were deposited by RF magnetron sputtering on glass substrates employing a sintered ceramic target and pure argon gas. The influence of substrate temperature on microstructure and optical characteristics of the deposited films were investigated by X-ray diffractometer (XRD) and spectrophotometer. The results demonstrate that all the ZnO films have preferred orientation along (002) direction. The substrate temperature significantly affects the crystalline quality and optical characteristics of the ZnO thin films. With the increase of substrate temperature, the mean grain size, lattice spacing and optical bandgap of the films increase, the dislocation density and micro strain decrease, and the average transmitance in the wavelength range of the visible spectrum also increases.

Abstract: Transparent conductive ZnGa₂O₄ thin films were prepared by magnetron sputtering. The chemical state of O, Zn and Ga in the deposited films was investigated by X-ray photoelectron spectroscopy (XPS), and the optical properties were characterized by optical transmittance spectra. The XPS studies reveal that no metallic Zn and Ga were detected in the ZnGa₂O₄ thin films, and Zn and Ga exist only in oxidized state. The optical bandgap was calculated by Tauc's theory and the optical constants were determined using Swanepoel's method. Furthermore, the dispersion behavior of the refractive index was studied by means of single-oscillator model, and the physical parameters and the refractive index dispersion parameter were obtained. The results provide some useful references for the potential application of the ZnGa₂O₄ thin films in optoelectronic devices.