Thickness effects on the physical characterization of nanostructured CuO thin films for hydrogen gas sensor

Abstract

In these studies, radio frequency (RF) magnetron sputtering was used to produce nanostructured CuO thin films on glass bases with different thicknesses of (250, 300, and 350 nm). X-ray diffraction (XRD) analysis of these films revealed a polycrystalline structure with a preferred peak along the (111) plane. The Scherrer formula was used to compute the grain size. It was found that the average grain sizes are 10.78 nm, 11.36 nm, and 11.84 nm for film thicknesses of 250, 3000, and 300 nm, respectively, while the dislocation density and strain values decline. The surface roughness decreased from 9.30 nm to 4.71 nm as the thickness increased, according to atomic force microscopy (AFM) data. As the thickness of the film grew, the root mean square (RMS) roughness likewise decreased from 9.18 nm to 4.29 nm. The homogenous, semi-spherical structure comprises uniformly distributed particles, as demonstrated by SEM images. The optical properties of the grown films showed that the absorption coefficient considerably increased with film thickness. Transmittance, band gap, refractive index, and extinction coefficient all decrease with increasing film thickness. The hydrogen gas measurements, indicated a reduction in sensitivity as the thickness and gas concentration increased at 30°C.