Self-Powered Photoelectrochemical (Al,Ga)N Photodetector with an Ultrahigh Ultraviolet/Visible Reject Ratio and a Quasi-Invisible Functionality for 360° Omnidirectional Detection

TLDR

Self‑powered ultraviolet photodetectors are essential for next‑generation optoelectronic devices. This study proposes and demonstrates a self‑powered photoelectrochemical photodetector that combines ultrahigh transmissivity, an ultrahigh UV/visible reject ratio, and high responsivity. The high UV/visible reject ratio and detection selectivity are achieved by removing the epitaxial substrate, while a SiO₂ layer suppresses leakage current and boosts photoresponsivity. The device delivers quasi‑invisible, 360° omnidirectional detection, can quickly identify light direction via angle‑dependent responsivity, and shows high stability for broad optoelectronic applications such as UV communication.

Abstract

Self-powered ultraviolet (UV) photodetectors (PDs) are promising and essential for the applications of next-generation optoelectronic devices. This work proposes and demonstrates a self-powered photoelectrochemical (PEC) PD with three excellent characteristics successfully, which are the ultrahigh transmissivity, ultrahigh UV/visible reject ratio and responsivity. Thanks to the ultrahigh transmissivity, the PD can achieve the critical factor of quasi-invisible functionality to realize the 360° omnidirectional detection. Due to the angle-dependent photoresponsivity, this PEC PD can be utilized for quickly identifying the light direction. Furthermore, as the epitaxial substrate can have a nonignorable visible response, the key reason for obtaining the ultrahigh UV/visible reject ratio and excellent detection selectivity should be the removal of the epitaxial substrate. It is also found that the SiO2 layer can significantly enhance the photoresponsivity by suppressing the leakage current. With a demonstrated high stability, this PD would enable a broad range of optoelectronic applications, including 360° omnidirectional detection and UV communication.