Fully Epitaxial Semiconductor Photoelectrode for UV–VIS Dual-Band Photodetection

High-performance spectrally distinctive photodetectors (PDs) are of great importance in sensing and information processing. PDs based on photoelectrochemical (PEC) principles are of particular interest due to their simple fabrication process and tunable photoresponse through both physical and chemical processes. Despite the recent advancement in PEC-PDs, they are far less ideal. For example, most of them are either not stable or not compatible with existing epitaxial semiconductor device platforms, whereas although III-nitride nanowire-based PEC-PDs can largely mitigate these drawbacks, dual-band photodetection is limited to the ultraviolet (UV) range. Herein, we show that by using fully epitaxial n-GaN/p-InGaN p–n heterojunction photoelectrodes on the Si substrate, the dual-band photodetection of III-nitride nanowire-based PEC-PDs can be extended to the visible (VIS) range. Moreover, the present photoelectrodes can also exhibit dual-polarity photocurrent under a fixed illumination condition by tuning the applied potential, extending their functionality. This study represents the first achievement of UV–VIS dual-band photodetection with simple, fully epitaxial semiconductor nanowire p–n heterojunctions. The discussion on the photocarrier dynamics further sheds light on the design of dual-band PEC-PDs based on emerging semiconductor nanowire p–n heterojunctions.