Physical Properties of Copper Oxide Thin Films Prepared by Sol–Gel Spin–Coating Method

Abstract

In this study, copper oxide thin films prepared by the sol–gel method, have been deposed onto glass substrates by the spin coating technique. Our target was to study their properties and improve them for photovoltaic use. These properties were optimized by varying the temperature annealing and the molar concentration of the precursor solutions. The effects of the annealing temperature on the structural and optical properties of the thin films are studied. It was found that the film treated at 550°C shows a higher absorbance. Then by using this optimized temperature, CuO thin films of various molar concentrations, were deposited at the same experimental conditions. The structural analysis by X- ray diffraction (XRD) shows that all the samples are polycrystalline with monoclinic crystal structure. Raman scattering measurements of all thin films confirms the structure of CuO. The optical properties of the films were characterized by UV–Visible–NIR spectrophotometry, which shows that the films show high absorbance in the visible region. Their optical band gap decreases from 3.68 to 2.44 eV when the molar concentration of precursor solutions increases from 0.1 to 0.5 M. The electrical measurements show that the resistivity of the films varies slightly from 84 Ω cm to 124 Ω cm as the molar concentration increases.