Electrical and optical characterization of fluorine-doped zinc oxide thin films deposited by spray pyrolysis technique

Abstract

The electrical and optical characterization of transparent and conducting Zinc Oxide and Fluorine doped Zinc oxide thin films, deposited by spray pyrolysis technique are presented. The optimum conditions for deposition have been established. The effects of air and vacuum annealing on electrical and optical properties of undoped ZnO and Fluorine doped ZnO films were investigated. Air annealing showed an increase in sheet resistance of the films while vacuum annealing showed a decrease in sheet resistance of the film was found to be in the range of 270-300. The thermoelectric power investigations of the doped ZnO films showed that the charge carries were electrons (n-type). The activation energies obtained for differently doped films were in the range of 0.47-0.65eV. Direct band gap of ZnO films was found to be 3.24eV. The highest transmittance obtained was about 82%. An attempt was made to fabricate ZnO: F/SiO2/p-Si solar cell which yielded an open circuit voltage of 0.235V, short circuit current density of 1.41mA/cm2, fill factor of 0.267 and efficiency of 0.11%. The low efficiency could be attributed to thick interfacial oxide layer.