Bandedge emission in sprayed ZnO thin films

ZnO thin films were grown by spraying aqueous solutions of zinc acetate on quartz and silicon substrates heated to 500°C. X-ray diffraction (XRD) studies show that the ZnO films crystallize in the hexagonal phase and are highly oriented along the [002] direction. SEM micrographs show that the surface of the films is uniformly covered with worm shaped particles. EDAX results together with XRD studies confirm that the synthesized films are single phase ZnO with good stoichiometry. The sharp absorption occurring near the band edge indicates high quality growth of the material. Room temperature photoluminescence (PL) studies of the sprayed films show a strong near band edge (NBE) emission. PL spectra obtained at low temperature (20 K) exhibit better resolved peaks of the NBE emission caused by the radiative recombination of free and bound excitons. The dominant free exciton emission observed in the PL spectra confirms the high quality of the sprayed ZnO layers.