Optical characteristics of Cu1-xFexO thin films prepared via electrophoretic deposition technique

Cu_1-xFe_xO (x = 0, 2, 4, and 6 at. %) thin films were deposited on fluorine-doped tin oxide (FTO) substrates using the electrophoretic deposition (EPD) technique. Before the EPD process, Cu_1-xFe_xO powders were synthesized using the solid-state method. In this method, the powders are mechanically milled up to 9 h followed by annealing at 450 °C for 2 h. The XRD patterns reveal that all the investigated films are pure polycrystalline phase CuO, with monoclinic structure and without any traces of Fe or its oxides. The FESEM morphology observations of all the films confirm the constitution of grains whose average size varies from 100 to 250 nm. Moreover, increase in Fe dopant amount led to a change in the number and size of the particle agglomerations and the number of porosities. The effect of Fe dopant concentration on the optical constants of CuO films was studied using a UV–Vis spectrophotometer. The estimated band gap values shown blue-shifted from 1.23 eV for pure to 1.49 eV for Cu_0·94Fe_0.06O. Furthermere, the refractive index and Urbach energy values were determined, and the correlation between the results obtained with XRD data and FESEM morphology is discussed.