Effect of substrate etching on electrical properties of electrochemically deposited CuO

The effect of Cu substrate etching on electrical properties of electrochemically deposited CuO was investigated. Four different etching methods were compared in this study-no etching, chemically etched in HNO3, ex situ electrochemically etched in H2SO4, and in situ electrochemically etched in the deposition solution. Surface roughness by atomic force microscopy was used to optimize the electrochemical etching processes. Metal/CuO diodes were fabricated by depositing various metals on Al, Ni, and Cu. Current-voltage characterization was performed to investigate the electrical properties of the as-deposited CuO films. CuO grown on electrochemically etched Cu substrates had favorable electrical properties over chemical etched and nonetched substrates as evidenced by better rectification behavior and lower current through the CuO films. Al/CuO diodes showed rectifying behavior, while Ni/CuO and Cu/CuO diodes both showed ohmic behavior. Transmittance measurements of as-deposited CuO showed that CuO has an indirect bandgap of 1.32 eV. Scanning electron microscopy revealed that CuO deposited at above 50 degrees C was polycrystalline, while amorphous below 50 degrees C. (c) 2006 The Electrochemical Society.