Spray pyrolysis deposition of ZnO thin films on FTO coated substrates from zinc acetate and zinc chloride precursor solution at different growth temperatures

ZnO thin films were fabricated using zinc chloride and zinc acetate precursors by the spray pyrolysis technique on FTO coated glass substrates. The ZnO films were grown in different deposition temperature ranges varying from 400 to 550 °C. Influences of substrate temperature and zinc precursors on crystal structure, morphology and optical property of the ZnO thin films were investigated. XRD patterns of the films deposited using chloride precursor indicate that (1 0 1) is dominant at low temperatures, while those deposited using acetate precursor show that (1 0 1) is dominant at high temperatures. SEM images show that deposition temperature and type of precursor have a strong effect on the surface morphology. Optical measurements show that ZnO films are obviously influenced by the substrate temperatures and different types of precursor solutions. It is observed that as temperature increases, transmittance decreases for ZnO films obtained using zinc chloride precursor, but the optical transmittance of ZnO films obtained using zinc acetate precursor increases as temperature increases.

Research highlights
► ZnO thin films were fabricated using Zn chloride/acetate precursors by the spray pyrolysis technique on FTO substrates at different growth temperatures.
► ZnO films obtained from acetate precursor have orientation along the (1 0 1) direction at high temperatures, but films from chloride have the same orientation at low temperature.
► The films deposited using acetate precursor had high density and small islands while those deposited using chloride precursor had low density and large islands at high growth temperature.
► As temperature increases transmittance decreases for ZnO films obtained from chloride precursor, but transmittance of films obtained from acetate increases as temperature increases.