Tuning optical, electrical and magnetic properties of fiber structured ZnO film by deposition temperature and precursor concentration

Highly transparent ZnO films were deposited on glass substrates using zinc acetate solution through cost effective spray pyrolysis method. A comprehensive study was carried out to understand the effects of deposition temperature and precursor concentrations on structure, surface morphology, optical, electrical and magnetic properties of the deposited films. All deposited films were polycrystalline in nature with hexagonal wurtzite structure. The films were preferentially oriented along (1 0 1) plane up to 723 K beyond which orientation changed to (0 0 2) plane. Irrespective of precursor concentration used, the films deposited at 673 K and 723 K showed fibrous structure. The films deposited at higher temperature led to enhanced transmittance and optical energy band gap. With higher precursor concentrations the transmittance decreased while the band gap increased. Photoluminescence studies revealed the presence of various defects leading to emission in the visible region apart from band to band transition near UV region. Lowest electrical resistivity was obtained for films deposited at 723 K which is of the order 102 Ω cm. At room temperature, all deposited films were diamagnetic while they were paramagnetic at 5 K.