Investigating the Impact of Substrate-to-Nozzle Distance on the Microstructure and Optical Properties of CuO Thin Films Deposited by Thermochemical Spray Technique

The characteristics of copper oxide (CuO) thin films deposited by thermal spray method on moving substrates at various distances from the nozzle to the substrate were investigated using XRD, SEM, and UV-Vis methods. The most significant characteristic in all the deposited films, according X-ray diffraction (XRD) study, was the (111) peak. Stable crystalline structure of the films was demonstrated by varying d-spacing values ranging from 0.245 Å to 0.246 Å at varied distances. Moreover, the Scherrer equation was used to determine the crystallite size; it was found that the size dropped as the distance separating the nozzle from the substrate rose. Particle size and porosity varied between films deposited at 15 cm and 30 cm according to SEM investigation. Whereas the films produced at 30 cm revealed bigger particles (10 nm), those deposited at 15 cm showed reduced particle sizes (20nm). The UV-Vis data revealed that light transmittance rose while light absorption dropped as the distance separating the nozzle from the substrate increased. The energy band gap (Eg) was deducing using the Tauc equation A larger energy band gap (2.35 eV) was found in the films deposited at 30 cm than in those formed at 15 cm (2.04 eV). Furthermore, noted was a rise in the absorption coefficient and refractive index with increasing distance, suggesting improved film absorption and conversion capability of course.