Growth of high quality CuO thin film and investigation of its abnormal luminescence behavior

Abstract

Given the widespread application of Copper oxide in fields such as energy and environment, it is crucial to conduct in-depth research on its growth and basic physical properties. In this investigation, Copper oxide films were fabricated using spin-coating method, and the impact of heat-treatment temperature on the structure and optical characteristics of the samples was revealed. The experimental results indicate that the use of a low-temperature homogeneous buffer layer can improve the densification of CuO thin films. Polishing up the quality of metal-oxide films through buffer layers is a commonly used method. Raman spectra show that all samples have a monoclinic structure, and their crystalline quality gradually improves with the increase of annealing temperature. The photoluminescence spectra show that all samples exhibit similar emission spectral profiles, including three emission bands with central wavelengths at 404, 478, and 569 nm, respectively. Based on the results of EDX, XPS, and other researchers’ reports, we suggest that the violet emission located at 404 nm comes from the interband transition of electrons; The blue emission with a wavelength of 478 nm is ascribed to the transition of electrons from the conduction band (CB) to the copper vacancy level; The yellow-green emission located at 569 nm maybe originates from electronic transitions associated with surface oxygen vacancy defects.