Photoluminescence Studies on Spray Pyrolysis Deposited ZnO-SnO2 Mixed Thin Films

Abstract

ZnO-SnO2 mixed thin films were prepared by the spray pyrolysis technique using different molar ratios of zinc and tin in the starting solution. These mixed thin films were analysed by X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). XRD patterns of mixed thin films indicate the presence of tetragonal casseterite structure of SnO2 and hexagonal wurtzite phase of ZnO. The grain sizes of mixed films were calculated from XRD patterns and found to be in the range of 17- 84 nm. Mixed thin films exhibit smaller grain size compared to that of pure thin films. Ultraviolet and visible emission peaks were observed in photoluminescence studies of these thin films. The relative contribution of the emission bands occurring from different kinds of defects is described in detail. UV emission peaks were mostly affected by the influence of ZnO. Blue shift in UV emission peaks suggests a reduction in grain size in mixed thin film and bandgap modulation caused by SnO2.