Evolution of copper ions in high-silica thin films

Abstract

The paper studies Thin Films based on Silica which doped with Copper Ions (SiO2:CuO) at A Molar Ratio of (1:0.20; 1:0.30; 1:0.40) Deposited on Quartz and Silicon Substrates. The films were obtained by ion sputtering in a gaseous medium (argon/oxygen) from High- Silica targets obtained by the Sol-Gel method. The morphology and structure of the films were studied using scanning electron microscopy and X-ray phase analysis. X-ray phase analysis of the films revealed that the structure of the films is polycrystalline and has a hexagonal structure. It has been established that the reduction of Cu+2 to Cu+ occurs during film preparation in argon, which is confirmed by the analysis of absorption spectra and XRD data. The obtained frequency dependences of the dielectric permittivity of SiO2:CuO films showed a decrease in the dielectric permittivity and dielectric loss tangent in the range of (103 to 106) Hz. It has been found that when the SiO2:CuO film thickness is less than 100 nm, a thin-film capacitor is not always formed. The calculation of the film band gap shows the presence of two energy bands corresponding to the SiO2:CuO and SiO2:Cu2O compositions. The band gap of Eg(CuO) changes with increasing concentration from 3.564 to 2.598 eV, and Eg(Cu2O) changes with increasing concentration from 5.299 to 3.586 eV. A dip corresponding to the plasmon effect is observed in the transmission spectra in the region of 600–650 nm.