The effects of zinc nitrate, zinc acetate and zinc chloride precursors on investigation of structural and optical properties of ZnO thin films

ZnO thin films were prepared using zinc chloride, zinc acetate and zinc nitrate precursors by spray pyrolysis technique on glass substrates at 550 °C. Structural and optical properties of ZnO films were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and optical transmittance spectra. Regardless of precursors, ZnO thin films are all in hexagonal crystallographic phase and have (0 0 2) preferred orientation. SEM images show completely different surface morphologies for each precursor in ZnO thin films. ZnO rod was observed only for zinc chloride precursor. The optical measurements reveal that films have a low transmittance and a direct band gap approximately 3.30 eV, which is very close to band gap of intrinsic ZnO.