THE INFLUENCE OF THE DOPING WITH ALUMINUM ON THE OPTICAL PROPERTIES OF ZnO THIN FILMS

Ion LUNGU Universitatea de Stat din Moldova

Abstract

ZnO nanostructured layers were synthesized from chemical solutions by the spray pyrolysis method. By using X-ray diffraction (XRD) method and UV-Vis spectroscopy, the effects of varying aluminium concentration on the optical properties of ZnO nanostructured layers were studied. The concentration of aluminium was set at 0, 1, 2, 3 and 5% in the initial solution. X-ray diffraction (XRD) analysis confirms that doping with 1% aluminium, compared to other concentrations, improves the crystal structure. As the concentration of Al increases, the size of the crystallites decreases. The study of UV-Vis spectroscopy of thin layers indicates an increased transmittance (~ 90%) in the visible region of the energy spectrum with a bandwidth of 3.23 eV for undoped ZnO and 3.32 eV for Al-doped ZnO, which is close to the “bulk” value of ZnO (3.36 eV). Keywords: ZnO, transmittance, reflectance, absorbance, spray pyrolysis, doped.