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Abstract: ZnO nano-pillars were prepared on the silica glass by the sol-gel method. The films were crystallized at various crystallized temperatures (600 °C, 650 °C and 700 °C) for 1 h under a pure oxygen atmosphere. The ZnO films had hexagonal structures and preferred a c-axis orientation of (002). Due to the diffused zinc atoms recombining with oxygen atoms at higher temperatures (≥650 °C), the ZnO nano-pillars grew continually from the ZnO grains or the ZnO grain boundaries. When increasing the crystallizing temperature, the quality of ZnO crystallization not only improved, but the ZnO nano-pillars also grew significantly and their length was around 30–150 nm. Notably, a severe decomposition reaction reduced the total volume of crystallization matrix (residual ZnO thin films and increased ZnO nano-pillars). The nano-pillar-thin film of 650 °C not only possessed a better crystallization, but also had the efficacy of nano-pillars that enhanced the optical characteristics. In addition, 5 at.% indium-doped ZnO was also synthesized and then compared with un-doped ZnO to clarify the contribution of indium dopants. [Copyright &y& Elsevier]

Abstract: Multi-functions (conductor, semiconductor and insulator) ZnInSnO (ZITO) transparent oxide thin films have been obtained by a co-sputtering system using ITO target and ZnO target with oxygen gas contents (0–8%). The ZITO film containing a small ITO content had the lowest resistivity (good electron mobility) and higher optical transmittance. In addition, the influences of thermal treatments (post-annealing and substrate temperature) on electrical properties and optical transmittance of ZITO films were studied. Photoluminescence (PL) of the ZITO film confirmed the contribution of ITO content and oxygen gas content on the photo-emission. The ZITO film with zinc atomic concentration of 58at.% was a good candidate for TCO material (3.08×10−4 Ωcm). Under the substrate temperature of 100°C or post-annealing temperature of 200°C, the properties of ZITO film could be improved. [Copyright &y& Elsevier]

Abstract: The ZnO thin films were prepared on the quartz substrate by the sol–gel method and the UV photodetector was constructed on the ZnO thin films, with a circular spiral structure in contact 30nm IrO2 electrodes. The ZnO thin films were crystallized at various temperatures (600–700°C) for 1h in a pure oxygen atmosphere, then were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) to investigate the crystallized thin film structures. From photoluminescence (PL) and I–V measurements, the 650°C thin film not only possessed better crystallization but also had nanowire structures that revealed excellent potential as a UV photodetector. [Copyright &y& Elsevier]

Abstract: ZnO and indium-doped ZnO (I x ZO) thin films were prepared on silica–glass substrates by the sol–gel method. The thin films were crystallized at 600°C and 700°C for 1h in 6.9×10−1 Torr under pure O2 atmosphere. The analyzed results were compared to investigate the structural characteristics and optical properties. The surface morphology of the I x ZO films was different from that of the ZnO films, and showed a thin overlay structure. In addition, the crystallization of I x ZO film was depleted at higher crystallized temperatures. From XRD analysis, the ZnO and I x ZO thin films possessed hexagonal structures. Notably, micro-In2O3 phases were observed in the I x ZO thin films using EDS. Both of In2O3 phases and the crystallization mechanism not only improved the peeling of structure, but also improved the electrical conductivity of I x ZO thin films. For the PL spectrum, the optical property of the I x ZO film was raised at a higher crystallization temperature. Although the In2O3 phases reduced the structural defects of I x ZO thin film, the optical effect of the residual In3+ was not enhanced completely at higher crystallized temperatures. [Copyright &y& Elsevier]

Abstract: Un-doped Al (0–9at.%) nanoparticles and doped ZnO powders were prepared by the sol–gel method. The nanoparticles were heated at 700–800°C for 1h in air and then analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectra and photoluminescence (PL). The results of un-doped (ZnO) and Al-doped ZnO (AZO) nanoparticles were also compared to investigate the structural characteristics and physical properties. XRD patterns of AZO powders were similar to those of ZnO powders, indicating that micro-Al ions were substituted for Zn atoms and there were no variations in the structure of the ZnO nanoparticles. From the XRD and SEM data, the grain size of the AZO nanoparticles increased from 34.41 to 40.14nm when the annealing temperature was increased. The Raman intensity of the AZO nanoparticles (Al=5at.%) increased when the annealing temperature was increased. Increasing the degree of crystalline not only reduced the residual stress, but also improved the physical properties of the nanoparticles. [Copyright &y& Elsevier]

Abstract: Temperature-dependent characteristics of ZnO Schottky diodes with Iridium (Ir) contact electrodes were investigated. Using Norde model, it was found that the effectively Schottky barrier heights of Ir on n-ZnO were around 0.837, 0.829, 0.801, 0.750 and 0.719eV when measured at 25, 30, 50, 100 and 150°C, respectively. Using Cheung’s method, it was found that Schottky barrier heights between Ir and the n-ZnO were 0.824, 0.823, 0.789, 0.743 and 0.740eV when measured at 25, 30, 50, 100 and 150°C, respectively. The large Schottky barrier heights suggest that Ir is a potentially useful material for ZnO-based ultraviolet Schottky barrier photodetectors and metal–semiconductor-metal photodetectors. [Copyright &y& Elsevier]

Abstract: We report the fabrication of ZnO-based metal–insulator–semiconductor (MIS) and metal–semiconductor–metal (MSM) photodetectors. With 5V applied bias, it was found that photocurrent to dark current contrast ratios of the ZnO MSM and MIS photodetectors were 2.9×102 and 3.2×104, respectively. It was also found that measured responsivities were 0.089 and 0.0083A/W for the ZnO MSM and MIS photodetectors, respectively, when the incident light wavelength was 370nm. Furthermore, it was found that UV to visible rejection ratios for the fabricated ZnO MSM and MIS photodetectors were 2.4×102 and 3.8×103, respectively. [Copyright &y& Elsevier]

Abstract: We report the fabrication of ZnO-based metal–insulator–semiconductor (MIS) and metal–semiconductor–metal (MSM) photodetectors. With 5V applied bias, it was found that photocurrent to dark current contrast ratios of the ZnO MSM and MIS photodetectors were 2.9×102 and 3.2×104, respectively. It was also found that measured responsivities were 0.089 and 0.0083A/W for the ZnO MSM and MIS photodetectors, respectively, when the incident light wavelength was 370nm. Furthermore, it was found that ultraviolet (UV) to visible rejection ratios for the fabricated ZnO MSM and MIS photodetectors were 2.4×102 and 3.8×103, respectively. [Copyright &y& Elsevier]