Structural, optical and photoluminescence investigations of nanocrystalline CuO thin films at different microwave powers

Abstract

Thin films of copper oxide were prepared through two steps: the formation of metallic copper thin films by DC sputtering technique and oxidizing the metallic copper films through microwave plasma chemical vapor deposition technique. X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) were used to detect the crystalline phases and the films morphology, respectively. Tenorite CuO phase with interlocking between grains were observed and detected. Optical and photoluminescence properties were investigated by UV–Vis-NIR to detect the optical transparency, optical band gap, and refractive index of the prepared films. The optical transmittance of the studied films was resolved by Swanepoel’s procedure due to the presence of the optical interference in such samples. The optical band gap values were observed to decrease from 2.355 to 1.986 eV as the microwave power increase. A strong UV emission at around 358 nm was observed in all CuO samples. Moreover, weak blue and green emission were also observed in the photoluminescence spectra.