Deposition of highly oriented ZnO films by spray pyrolysis and their structural, optical and electrical characterization

Abstract

Thin films of zinc oxide (ZnO) have been deposited onto glass substrates using a simple and inexpensive spray pyrolysis technique. A nonaqueous methanolic solution of zinc acetate was used as a spraying solution. The concentration of the solution was varied between 0.025 to 0.4 M. The films prepared at different solution concentrations were uniform and well adherent to the substrates. X-ray diffraction (XRD) studies showed that all the films were polycrystalline having hexagonal wurtzite-type crystal structure with strong orientation along (002) plane except 0.025 M, which exhibits a strong orientation in along (100) plane. The bandgap energy, electrical resistivity and thermoelectric power of the films were found to be dependent on the solution concentration. As solution concentration increases, the bandgap energy attenuates from 3.33 to 3.24 eV. The room temperature electrical resistivity was found to be vary in the range 10 2 to 10 −3 Ω cm, whereas thermoelectric power increases from 1×10 −6 to 8×10 −5 V/K. All the films showed n-type conductivity as evidenced from thermoelectric power (TEP) measurement.