Synthesis and investigating effect of tellurium-doping on physical properties of zinc oxide thin films by spray pyrolysis technique

In this article, we use a simple spray pyrolysis technique to prepare Tellurium doped zinc oxide thin films by varying the doping concentration in the range 0%, 4% and 8% at a constant substrate temperature of 550 °C. The X-ray diffraction (XRD) patterns exhibit hexagonal crystal structure. The preferred orientation in all samples is along the (002) plane in which the intensity of the peak decreases with the increase in Te-doping. The field emission scanning electron microscopic (FESEM) images prove that the surface is composed of rod-shaped grains, which the rod-shaped grains disappear with an increase in Te-doping. The evaluated amount of root mean squares (RMS) roughness for the undoped ZnO, 4% and 8% Te-doped ZnO thin films by atomic force microscopy (AFM) are as 13.6, 23.7 and 61.7 nm, respectively. The results of Hall effect measurement reveal to have n-type conductivity in all samples. According to the optical features in our experiments, we show that the films with high Te-doping concentration had lower transmittance. It is also evident that with the addition of Te dopant, the band gap of thin film decreases. However, increasing the Te concentration increases the band gap of thin film. In addition, the contact angle measurements explicitly reveal that the surface of the films were hydrophobic.