Effect of film thickness on characteristic properties of thermally evaporated copper oxide thin films

Abstract

Copper oxide (CuO) is regarded as one of the most promising materials for heterojunction solar cells. Due to its bandgap (~1.2 eV), CuO thin films have been used as the absorber material for the development of photonic devices. In this study, CuO thin films were deposited on the cleaned FTO glass substrates by varying the deposition duration in order to vary layer thicknesses using the thermal evaporation technique (PVD). The chamber pressure was maintained at 1.5 ×10 -5 Torr. Morphological and optical properties of the synthesized films were studied as a function of the film thickness. Scanning electron microscopy and UV–Vis spectroscopy were used to explore the morphology and optical properties of the films, respectively. Field emission scanning electron microscopy (FESEM) analysis revealed formation of nanoparticles with sizes in between 77.78 nm to 102.94 nm. Morphological studies have revealed that the uniformity of the film surface, and the average Nano particle diameter were found to increase with sample thickness increase. The bandgap was estimated from optical absorption measurements. The calculated bandgap value of copper oxide thin films increases from 1.78 eV to 2.78 eV when film thickness decreases. The lowest bandgap value was reported for the sample thickness at 50 nm. Moreover, the optical properties such as the bandgap energy of CuO were found to be influenced by the sample thickness. The study uncover method.