Vertically aligned ZnO/Ga2O3 core/shell nanowire arrays as self-driven superior sensitivity solar-blind photodetectors

Abstract

With a large interfacial area, better light absorption ability and well-controlled morphology, vertically arrayed one-dimensional core/shell nanostructures are considered as ideal candidate geometries for high-performance photodetectors. Herein, vertically aligned ZnO nanowire arrays were fabricated by the vapor phase transport approach and then homogeneously coated with 20 nm thick monoclinic Ga₂O₃ through sputtering methods, and can be used as self-driven solar-blind photodetectors. These devices exhibit excellent photosensitive characteristics with a large I_light/I_dark ratio of 2.64 × 10⁴, an ideal detectivity of 6.11 × 10¹² cm Hz^1/2 W⁻¹, and a superior responsivity of 137.9 mA W⁻¹ under 254 nm light without an exterior power supply, which are much higher than those of other previously reported self-powered Ga₂O₃-based photodetectors. What is more, an ultrafast response speed (rise time ∼28.9 μs and fall time ∼85.7 μs) is observed in the photodetectors by the time-resolved photoresponse test. Such excellent performances are assigned to the unique core–shell nanoarchitecture and built-in electric field at ZnO and Ga₂O₃ junction interfaces can rapidly separate photogenerated carriers. Our work provides a facile yet efficient fabrication procedure to construct self-powered core/shell nanowire arrays as solar-blind photodetectors for huge application potential in future optoelectronic devices.