Fabrication of coaxial p-Cu2O/n-ZnO nanowire photodiodes

The authors report the deposition of Cu2O onto vertically well aligned ZnO nanowires by DC sputtering. The average length, average diameter and density of these VLS-synthesized ZnO nanowires were 1 μm, 100 nm and 23 wires/μm2, respectively. With proper sputtering parameters, the deposited Cu2O could fill the gaps between the ZnO nanowires with good step coverage to form coaxial p-Cu2O/n-ZnO nanowires with a rectifying current–voltage characteristic. Furthermore, the fabricated coaxial p-Cu2O/n-ZnO nanowire photodiodes exhibit reasonably large photocurrent-to-dark-current contrast ratio and the fast responses.