Optical properties of copper oxide thin films implanted with chromium ions

Abstract

Copper oxides are nontoxic semiconductors with good stability and abundance of raw materials. In each of the applications, it is advisable to look for a method to improve the properties of thin films of these materials, such as electrical conductivity or light absorption. In this work, thin films were prepared by reactive magnetron sputtering and doped with chromium using the ion implantation method. The samples were implanted with chromium ions with energy of 10–25 keV and various doses ranging from 1 × 1014 to 1 × 1017 cm−2. Their optical properties were investigated using spectroscopic ellipsometry and spectrophotometry with absorption measurement. Multilayer models of the dielectric function of materials were established based on oscillator equations to obtain the values of optical parameters such as refractive index and extinction coefficient. Measurements using the ellipsometer allowed us to examine the homogeneity of the samples after deposition, as well as after the implantation process, by measuring 4 × 4 mm2 maps of the pseudorefractive index of the samples. Ion implantation affects the optical properties of copper oxides, and these changes are expected to come from the top thickness of the implanted films, i.e., the range in which the implanted ions penetrate. Using multilayer models to analyze the results of spectroscopic ellipsometry, it was possible to estimate the thickness of the layer that has the greatest impact on the optical properties of the oxides.