Effect of Substrate Temperature and Sprayed Methanol on Nanostructure, Optical and Electrical Properties of ZnO Films

Polycrystalline zinc oxide (ZnO) thin films were synthesized on sodalime glass substrates using the chemical spray technique at different substrates temperatures (400, 450 and 500 °C) and for different amounts of methanol based solutions (30, 50 and 70 ml). The compositional, structural, morphological, optical and electrical properties were studied with Rutherford backscattering spectrometry (RBS), X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet and visible spectroscopy and the four-point methods, respectively. The results show that for a fixed substrate temperature, the atomic zinc concentration in the films increases with the volume of sprayed solution. On the other hand, the particle size of ZnO thin films shows a direct relation with the amount of sprayed solution. In the same way the optical band gap energy seems to be sensitive to the volume of the sprayed solution and the substrate temperature. The minimum resistivity values for all the ZnO thin films were measured in the samples deposited at 500 °C. The average particle size showed great variation that range from 59.7 to 148.3 nm.