A surface oxide thin layer of copper nanowires enhanced the UV selective response of a ZnO film photodetector

Abstract

Copper nanowires (Cu NWs) with good crystallinity and high aspect ratio were prepared by a facile hydrothermal method at low temperature, and they were dispersed on a smooth and thin layer of ZnO film to construct a photodetector (PD). This Cu NW/ZnO PD exhibits a remarkably higher UV-visible rejection ratio (∼160), which is almost 13 times that of a bare ZnO PD (12.5) and more than twice that of a Cu film/ZnO PD (67.7). The high UV light selective response of the Cu NW/ZnO PD is caused by the dramatic decrease of the photoresponsivity in the visible light region and the high photocurrent in the UV region due to the presence of a potential barrier between ZnO and Cu NWs. Interestingly, the commonly observed thin layer of CuO (2 nm) on the surface of Cu NWs plays a significant role in the enhanced UV light selective response performance. The results demonstrate that the height of the Schottky barrier and the thickness of the depletion layer are both reduced owing to the oxidized copper layer, which leads to the excellent UV selective response. Our results indicate that Cu NWs, as a multifunctional material, could have diverse applications in the field of optoelectronics. And this detector obtained by a simple preparation method shows great potential in the actual applications in the future.