Abstract
Undoped and Mg-doped ZnO thin films were deposited on Si(100) and quartz substrates by the sol–gel method. The thin films were annealed at 873K for 60min. Microstructure, surface topography and optical properties of the thin films have been measured by X-ray diffraction (XRD), atomic force microscope (AFM), UV–vis spectrophotometer, and fluorophotometer (FL), respectively. The XRD results show that the polycrystalline with hexagonal wurtzite structure are observed for the ZnO thin film with Mg:Zn=0.0, 0.02, and 0.04, while a secondary phase of MgO is evolved for the thin film with Mg:Zn=0.08. The ZnO:Mg-2% thin film exhibits high c-axis preferred orientation. AFM studies reveal that rms roughness of the thin films changes from 7.89nm to 16.9nm with increasing Mg concentrations. PL spectra show that the UV–violet emission band around 386–402nm and the blue emission peak about 460nm are observed. The optical band gap calculated from absorption spectra and the resistivity of the ZnO thin films increase with increasing Mg concentration. In addition, the effects of Mg concentrations on microstructure, surface topography, PL spectra and electrical properties are discussed.
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