Fabrication and Characterization of Coaxial p-Copper Oxide/n-ZnO Nanowire Photodiodes

The deposition of copper oxide onto vertically well-aligned n-ZnO nanowires by sputtering and the fabrication of p-copper oxide/n-ZnO coaxial nanowire photodiodes are reported. It was found that we could change the copper oxidation number to obtain Cu₂O/ZnO nanowire photodiode, Cu₄O₃/ZnO nanowire photodiode and CuO/ZnO nanowire photodiode by simply changing the O flow rate during deposition. It was also found that noise equivalent powers were 6.1 × 10^-11, 3.8 × 10^-10, and 7.2 × 10^-8 W while normalized detectivities were 6.35 × 10⁹, 1.02 × 10⁹, and 5.37 × 10⁶ cmHz^0.5 W^-1 for the fabricated Cu₂O/ZnO nanowire photodiode, Cu₄O₃ /ZnO nanowire photodiode and CuO/ZnO nanowire photodiode, respectively.