High-responsivity and self-powered photoelectrochemical ultraviolet photodetector based on self-supporting SiC/GaN heterojunction nanoarrays for reliable underwater optical communication applications

Controlling the interface properties and surface carrier dynamics of nanostructured semiconductors is crucial for enhancing the electrical and optical performance of photoelectrochemical (PEC) photodetectors (PDs). Herein, a novel self-powered PEC ultraviolet (UV) PD applicable to harsh underwater environments is developed based on integrated self-supporting SiC/GaN heterojunction nanowire arrays. Whole single-crystal integrated self-supporting SiC nanoarrays are encapsulated by high-quality GaN films via two-step anodization and high-temperature nitridation processes. The optimized heterojunction nanoarrays PEC UV PD with 40 min nitridation duration (SiC/GaN-40) demonstrates outstanding photodetection capabilities with high responsivity ( R λ , 698 mA/W), excellent detectivity ( D ⁎ , 1.66 × 10 11 Jones), remarkable external quantum efficiency ( EQE , 231.2 %), and rapid rise/decay times ( τ r / τ d , 127.93/214.92 ms) under 375-nm light illumination at 0.6 V bias voltage. Moreover, the SiC/GaN-40 device demonstrates excellent self-powered performance, achieving exceptional R λ , D ⁎ , EQE, and τ r / τ d , of 588.24 mA/W, 9.3 × 10 10 Jones, 194.9 %, and 160/199 ms, respectively. Furthermore, the device exhibits excellent long-term operational and aging stability even under harsh underwater environments, such as pH-universal and wide-temperature solutions. This study provides a valuable reference for exploring high-responsivity and reliable PEC PDs suitable for harsh underwater optical communication, thus advancing the heterojunction and interfacial engineering strategies for next-generation optoelectronics.