Self-powered NiO@ZnO-nanowire-heterojunction ultraviolet micro-photodetectors

In recent years, ultraviolet (UV) photodetectors based on nanomaterials of wide-bandgap semiconductors have emerged as a hot topic for miniaturizing these devices and saving energy. Herein, for the first time, we report a micro p-n nanowire-heterojunction constructed from a NiO-coated Ni core-shell nanowire combined with a ZnO layer (NiO@ZnO) and a UV photodetector based on this micro p-n nanowire-heterojunction. The micro NiO@ZnO-nanowire-heterojunction shows good rectification effects with a rectification ratio of 6000 at a  ± 2 V applied bias and a turn-on voltage of 0.5 V. The UV photodetector exhibits excellent performances of self-powered UV photodetection with a peak photoresponsivity of 17 mA/W under zero bias at the wavelength of 312 nm. The cutoff wavelength is located at 362 nm, and a dark current is ∼0.25 pA. Our findings provide an alternative approach to miniaturize UV detectors for daily carrying based on nanowire-heterojunction materials.