Chemical deposition of ZnO films from ammonium zincate bath

Zinc oxide (ZnO) thin films were deposited from ammonium zincate bath following a chemical dipping technique. Films in the thickness range 0.25–4.0 μm could be prepared by varying the ammonium zincate bath concentration (in the range 0.03–1.5 M) and number of dipping (0–200). Higher values of bath concentration produced nonadherent and poor quality films. The film growth rate was found to be a sensitive function of bath pH. The critical range of pH value for adherent and good quality films was found to be 11.0–11.1. Structural characterization by scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicate the formation of polycrystalline ZnO with strong c-axis orientation. The films were found to be highly resistive with dark resistivity of the order of 105 Ω cm. The electrical conductance was studied in the temperature range 300–650 K. The characteristic effect of chemisorption was found to influence the electrical properties of the films.