p-Cu2O-shell/n-TiO2-nanowire-core heterostucture photodiodes

This study reports the deposition of cuprous oxide [Cu 2 O] onto titanium dioxide [TiO 2 ] nanowires [NWs] prepared on TiO 2 /glass templates. The average length and average diameter of these thermally oxidized and evaporated TiO 2 NWs are 0.1 to 0.4 μm and 30 to 100 nm, respectively. The deposited Cu 2 O fills gaps between the TiO 2 NWs with good step coverage to form nanoshells surrounding the TiO 2 cores. The p-Cu 2 O/n-TiO 2 NW heterostructure exhibits a rectifying behavior with a sharp turn-on at approximately 0.9 V. Furthermore, the fabricated p-Cu 2 O-shell/n-TiO 2 -nanowire-core photodiodes exhibit reasonably large photocurrent-to-dark-current contrast ratios and fast responses.