Investigation of CuO Thin Films Produced by Ultrasonic Spray Pyrolysis Method Depending on Substrate Temperature

In this study, the CuO thin films were deposited on glass substrates at different substrate temperatures (350, 400, 450, and 500 ºC) by the ultrasonic spray pyrolysis (USP) method and then annealed at 525 ºC. In X-ray diffraction (XRD) analysis, the peak intensity was not found in thin films at 350 ºC substrate temperature and as-grown conditions. Two distinct peaks were observed at ~36º and ~39º in the XRD patterns of other films. These peaks are characteristic peaks of the monoclinic crystal structure of CuO. Atomic force microscopy (AFM) and scanning electron microscope (SEM) images of the produced thin films were examined. The surfaces of thin films are not smooth. After annealing, grain agglomerations were formed. The optical properties of the CuO thin films were analyzed by ultraviolet-visible region (UV-Vis) measurements. Forbidden band gap values (Eg) were calculated from Tauc graphs for as-grown and annealed samples. It has been observed that the structural, morphological, and optical properties of CuO thin films produced by the USP method can be controlled by the substrate temperature.