Characterization of Cu2O/CuO nanowire arrays synthesized by thermal method at various temperatures

Cu₂O/CuO nanowires (NWs) were grown by thermal oxidation of copper sheet at various temperatures. The thickness and surface roughness of the oxide layers were measured using profilometer, and it was found that they increase with increasing growth temperature. X-ray diffraction patterns revealed the formation of mixed cubic Cu₂O and monoclinic CuO phases, and the portion of the monoclinic CuO increased with growth temperature. Scanning electron microscope images revealed that the morphologies of all the samples have nanowires with diameters and lengths that depend on the growth temperature. A growth mechanism of these nanowires was proposed. The estimated optical band-gap values for Cu₂O/CuO-mixed NWs grown at 550, 600, and 650 °C are 2.56, 2.40, and 2.27 eV, respectively. The Cu₂O/CuO NWs showed broad emission peaks in the range 335–480 nm, which can be a combination of several peaks. The room-temperature resistivity values decreased with increasing growth temperature. The Cu₂O/CuO NWs have semiconducting behavior with two linear parts on Arrhenius plot for conductivity that gave two different activation energies.