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 Cu
₂
O/ZnO nanowire photodiode, Cu
₄
O
₃
/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 × 10
⁹
, 1.02 × 10
⁹
, and 5.37 × 10
⁶
cmHz
^0.5
W
^-1
for the fabricated Cu
₂
O/ZnO nanowire photodiode, Cu
₄
O
₃
/ZnO nanowire photodiode and CuO/ZnO nanowire photodiode, respectively.