title: Wire-shaped ultraviolet photodetectors based on a nanostructured NiO/ZnO coaxial p-n heterojunction via thermal oxidation and hydrothermal growth processes.
abstract: We report the facile fabrication of wire-shaped ultraviolet photodetectors (WUPDs) by employing a nanostructured zinc oxide (ZnO)/nickel oxide (NiO) coaxial p-n heterojunction. The WUPD consists of a ZnO/NiO coaxial Ni wire and a twisted gold (Au) wire where the Ni and Au are used as the anode and cathode, respectively. For the coaxial p-n heterojunction, the NiO nanostructures (NSs) and the ZnO nanorods (NRs) are subsequently formed on the surface of Ni wire via thermal oxidation and hydrothermal growth processes. With an applied bias of -3.5 V, the WUPD exhibits good photoresponsivity of 7.37 A W(-1) and an external quantum efficiency of 28.1% at an incident light wavelength of 325 nm. Under the UV illumination at a wavelength of 365 nm, the dark current and photocurrent are -3.97 × 10(-7) and -8.47 × 10(-6) A, respectively. For enhancing the photocurrent, the WUPD is threaded through a silver (Ag) coated glass tube which acts as a waveguide to concentrate the UV light of 365 nm on the WUPD. As a result, the photocurrent is significantly improved up to -1.56 × 10(-5) A (i.e., 1.84 times) at the reverse bias of -3.5 V.
authors.affiliation: Department of Electronics and Radio Engineering, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 446-701, South Korea. jsyu@khu.ac.kr.
authors.forename: Yeong Hwan
authors.initials: YH
authors.lastname: Ko
authors.forename: Goli
authors.initials: G
authors.lastname: Nagaraju
authors.forename: Jae Su
authors.initials: JS
authors.lastname: Yu