Correlation between optical and structural properties of copper oxide electrodeposited on ITO glass

In this paper we study the growth of copper oxide (Cu2O) thin films on indium tin oxide (ITO)-coated glass substrate by electrochemical deposition. We vary the applied potential from -0.50 to -0.60 V vs. Ag/AgCl in order to have a pure Cu2O. The copper oxide thin films properties are obtained using Spectroscopic Ellipsometry (SE) in the frame of the Forouhi and Bloomer model. This model demonstrates that depending on the applied cathodic potential pure or mixed phases of CuO and Cu2O can be obtained. Structural, morphological and optical properties are performed in order to confirm the SE results. X-ray diffraction analysis of the films reveals a mixed phase for a potential lower than -0.60V vs. Ag/AgCl while a high purity is obtained for this last potential. The optical band gap energy (E-g) is evaluated using the tauc relation. Pure Cu2O having a band gap of E-g = 2.5 eV and a thickness around 900 nm are therefore successfully obtained with an applied potential of -0.60 V. Raman measurements show the characteristic modes of Cu2O with a contribution of CuO modes at 618 cm (1). The intensity of the CuO modes decreases as the applied cathodic potential increases, leading to pure copper oxide layers. (C) 2014 Elsevier B. V. All rights reserved.