A Self‐Powered Photoelectrochemical Detection Device Using Scalable InGaN/GaN Nanowire Arrays

Abstract Photoelectrochemical photodetectors (PEC‐PDs) offer several advantages, including simple and low‐cost fabrication, self‐powered operation, high photoresponse, and strong environmental sensitivity. In this work, we report the self‐powered PEC photodetection characteristics of nanowire (NW)‐based, green‐emitting InGaN/GaN multiple quantum well (MQW) PEC‐PDs fabricated via a scalable top‐down process. The nanowire geometry significantly enhances the photoresponse compared to planar InGaN/GaN photoelectrodes, attributed to the increased solid–liquid interfacial area and improved carrier transport. A maximum photocurrent density of 16 mAcm ⁻² (twice that of the planar structure) is recorded under 365 nm illumination at 43.5 mWcm ⁻² without external bias. The device exhibits strong ultraviolet sensitivity with a peak at 365 nm and an extended response into the visible region. Notably, a high photoresponsivity of ≈330 mAW ⁻¹ is achieved at a lower illumination intensity of 0.7 mWcm ⁻² . The photodetector further demonstrates fast, stable, and reproducible performance across different biases and illumination conditions. These results highlight the strong potential of InGaN/GaN MQW NW‐based PEC photodetectors for scalable, efficient, and stable self‐powered optoelectronic applications.