Noise Properties of Low-Temperature-Grown Co-Doped ZnO Nanorods as Ultraviolet Photodetectors

The growth of vertically aligned cobalt-doped ZnO (Co-ZnO) nanorods on a glass substrate using a low-temperature hydrothermal method is reported. A Co-ZnO nanorod metal-semiconductor-metal ultraviolet photodetector (PD) was also fabricated. The ratio of UV-to-visible rejection of the fabricated PD was approximately 11700 when biased at 1 V with a sharp cutoff at 380 nm. With an incident light wavelength of 380 nm and an applied bias of 1 V, the measured responsivity of the PD was found to be 19.8 A/W. Furthermore, the dark noise equivalent power (NEP) and photo NEP of the fabricated Co-ZnO nanorod MSM PD were 1.3 × 10^-13 and 1.8 × 10^-11 W at the corresponding dark detectivities (D*) and photo D* of 1.1 × 10¹⁴ and 7.3 × 10¹¹ cm · Hz ^0.5 · W ^-1, respectively.