Characterization of CuZnO Nanocomposite Thin Films Prepared from CuO–ZnO Sputtered Films

Abstract

Copper oxide–zinc oxide (CuO–ZnO) thin films were prepared by a sputtering technique to examine the creation of a CuZnO thin-film nanocomposite. The base film was a zinc oxide layer. A copper oxide layer was deposited on glass coated with ZnO for different deposition times. The structure was examined by x-ray diffraction analysis. Plane (002) was detected for ZnO phase, while planes (111) and $\left( {\bar{1}11} \right)$ were detected for CuO phase. The crystallite size was calculated for both ZnO and CuO. The crystallite size of CuO phases increased with increasing deposition time, whereas the size of crystals of ZnO phase decreased. The film morphology and roughness were evaluated by scanning electron microscopy. Agglomeration of fine particles was observed. The film roughness decreased from 0.0685 nm for base ZnO films to 0.0357 nm for 800 s CuO–ZnO films. Elemental analysis of the film components was carried out by energy-dispersive x-ray spectroscopy. The ratio of O atoms remained constant at 50 at.%, while the Zn content decreased from 50% for the base sample to 27.66% for the 800 s CuO–ZnO sample. Optical properties, such as the optical absorption spectra, optical transition, and refractive index of the prepared films, were investigated. The optical transition was affected by the CuO layer and the film thickness. The optical bandgap decreased from 3.258 eV for ZnO films with thickness of 107 nm to 3.162 eV for 800 s CuO–ZnO films with thickness of 163 nm. Nonlinear optical behavior was deduced from the optical parameters, and was enhanced by the presence of CuO layers, increasing from 4.151 × 10⁻¹¹ esu for the ZnO sample to 4.434 × 10⁻¹¹ esu for the 800 s CuO–ZnO sample. The photoluminescence spectra of the films were investigated and interpreted.