Growth of zinc oxide thin films using different precursor solutions by spray pyrolysis technique

The present paper deals with the influence of precursor salt source on the properties of zinc oxide (ZnO) thin films prepared by spray pyrolysis. For this purpose, three zinc salt sources were studied including zinc acetate, zinc chloride, and zinc nitrate. X-ray diffraction (XRD), scanning electron microscopy (SEM), and optical transmittance spectra were used to investigate the structural and optical properties of ZnO thin films. Regardless the used precursor, ZnO thin films have the Wurtzite hexagonal crystallographic phase. SEM images reveal that the ZnO thin films surface morphology strongly governed by the precursor source nature. ZnO thin films prepared with zinc acetate salt are smooth, highly transparent and composed of small particle size. While, films prepared with zinc chloride are dense, owing a good crystallinity with a high texturation along (002) and rough surface film with larger particle size. The effect of solution salt is explained in term of the difference in the viscosity and the surface tension of the used solution. We inferred that high viscosity and surface tension solution such as the prepared one with zinc chloride, hinder the droplet motion on substrate surface in contrary to the solution prepared with zinc acetate. The PL emission spectra of films recorded at room temperature in the wavelength range 340–800 nm indicated that the salt solution has less effect on the electronic defects in the synthetized ZnO thin films.