Enhanced photoresponse of self-powered ZnO-based photoelectrochemical-type UV photodetectors via Ga-doping for optical communication application

Wide-bandgap metal-oxide semiconductors hold promise for self-powered photoelectrochemical (PEC) type UV photodetectors (PDs) due to their inherent photoelectric properties and durability. However, inadequate charge carrier separation and transport remain a fundamental challenge for practical applications. Herein, the extraordinary efficacy of introducing gallium (Ga) into ZnO nanowire to design high-performance PEC-type PDs is demonstrated. The obtained Ga-doped ZnO (ZnO:Ga) PEC-type photodetectors exhibit superior UV photoresponse performance, featuring an exceptionally high responsivity of 233.26 mA/W, an excellent detectivity of 4.18 × 1012 Jones, and a fast response/recovery time of 159/150 ms under 365 nm illumination without external bias voltages. These accomplishments outperform the majority of previously reported PEC-type UV PDs. It is found that the unique properties of ZnO:Ga nanowires, including improved donor density and steeper band bending at solid-liquid interface, significantly enhance the generation, transfer, and separation of photoexcited charge carriers, thus contributing to the superior photodetector's performance. In addition, a secure UV communication system using international Morse code is set to demonstrate the feasibility of ZnO:Ga nanowires PEC-PD as a self-powered optical receiver. This study introduces a promising approach to develop self-powered photodetectors that are highly stable, cost-effective, and poised for integration into future multifunctional optoelectronic devices.