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Abstract: Al-doped ZnO (ZnO:Al) thin films with different Al contents were deposited on Si substrates using the radio frequency reactive magnetron sputtering technique. X-ray diffraction (XRD) measurements showed that the crystallinity of the films was promoted by appropriate Al content (0.75wt.%). Then the ZnO:Al film with Al content of 0.75wt.% was annealed in vacuum at different temperatures. XRD patterns revealed that the residual compressive stress decreased at higher annealing temperatures. While the surface roughness of the ZnO:Al film annealed at 300°C became smoother, those of the ZnO:Al films annealed at 600 and 750°C became rougher. The photoluminescence (PL) measurements at room temperature revealed a violet, two blue and a green emission. The origin of these emissions was discussed and the mechanism of violet and blue emission of ZnO:Al thin films were suggested. We concluded that the defect centers are mainly ascribed to antisite oxygen and interstitial Zn in annealed (in vacuum) ZnO:Al films. [Copyright &y& Elsevier]

Abstract: Al-doped ZnO (ZnO:Al) thin films were deposited on Si substrates using the radio-frequency reactive magnetron sputtering technique. Effect of Al contents and annealing treatments on the structural and photoluminescence (PL) properties of ZnO films was investigated. The results showed that crystallinity of the films improved first with the increasing of Al content. However, as the Al content further increased more than 0.75wt %, the crystallinity was deteriorated. Meanwhile, the crystal quality of ZnO:Al thin films (Al content is 0.75wt %) was markedly improved after annealing at 600°C for 0.5h. Four main emission peaks located at 390, 445, 490 and 530nm were observed from PL spectra. As Al content was increased to 1.14wt %, the intensity of the blue peak (∼445nm) and the green peak (∼490nm) increased and the full width at half maxima (FWHM) decreased, and blue centre blue shifted to 429nm. A similar result can be obtained after annealing 600°C for 0.5h. This is attributed to Al doping and annealing treatment lead to the change of contents of antisite oxygen and interstitial Zn-related defects in the films. [Copyright &y& Elsevier]

Abstract: Pure and Al-doped ZnO (ZnO:Al) films have been deposited using radio frequency (RF) reactive magnetron sputtering at the O2:Ar ratio of 10:10, 6:10, and 2:10sccm and 150°C. The substrate temperatures were room temperature (RT), 150, 250, and 350°C and the O2:Ar ratio was 6:10sccm during the magnetron sputtering. The microstructures and optical properties in doped ZnO films were systematically investigated by X-ray diffraction (XRD) and fluorescence spectrophotometry. The results indicate that ZnO:Al films prepared at 250°C and 6:10sccm had the best crystal quality among all ZnO:Al films. Photoluminescence (PL) measurements at room temperature reveal a green and two blue emissions. The origin of these emissions is discussed. In addition, the intensity of blue emission peak first increased and then decreased as the substrate temperature shifted from RT to 350°C. The most intense blue luminescence was obtained from a sample grown at the O2:Ar ratio of 6:10sccm and 150°C. [Copyright &y& Elsevier]

Abstract: Al-doped ZnO (ZnO:Al) thin films with c-axis preferred orientation were deposited on glass substrates using the radio frequency reactive magnetron sputtering technique. The effect of Al concentrations on the microstructure and the luminescence properties of the ZnO:Al thin films were studied by atomic force microscopy (AFM), X-ray diffraction (XRD), and fluorescence spectrophotometer. The results showed that the crystallization of the films was promoted by appropriate Al concentrations; the photoluminescence spectra (PL) of the samples were measured at room temperature. Strong blue peak located at 437nm (2.84eV) and two weak green peaks located at about 492nm (2.53eV) and 524nm (2.37eV) were observed from the PL spectra of the four samples. The origin of these emissions was discussed. In addition, absorption and transmittance properties of the samples were researched by UV spectrophotometer; the UV absorption edge shifted to a shorter wavelength first as Al was incorporated, and then to a longer wavelength with the increasing Al concentrations. The optical band gaps calculated based on the quantum confinement model are in good agreement with the experimental values. [Copyright &y& Elsevier]