Transparent and all oxide-based highly responsive n-n heterojunction broadband photodetector

Abstract

There is an imperative need for a single photodetector that can be used to detect the entire electromagnetic spectrum from the ultraviolet (UV) to the near-infrared (NIR). Such a device can reduce the cost and surface area required for device integration. In addition to broadband photodetection, optical transparency must be considered as another critical parameter. Poor transparency or opacity renders their use a deprecated choice in transparent electronics. In this paper, a completely transparent, electrode-free n-n heterojunction (n-ZnO/n-V2O5) photodetector is developed for high responsivity and microsecond responses. This is the least-studied type of heterojunction. It is a Schottky junction and can provide rapid device performance due to its unipolar carrier transport. The wide bandgap of ZnO and the narrow bandgap of V2O5 make this heterojunction a transparent broadband photodetector. The n-ZnO/n-V2O5 photodetector offers> 50% optical transmittance in the Vis-NIR region, with remarkably high photoresponsivities of 18.86 A/W, 6.10 A/W, and 4.40 A/W in the UV, Vis, and NIR regions, respectively. The device also offers high detectivity, high external quantum efficiency, and fast rise and fall times of 230 and 340 µs, respectively. Briefly, this work provides a path towards the development of transparent, electrode-free broadband photodetectors for next-generation transparent electronics.