Oxygen-vacancy-dependent high-performance <i>α</i>-Ga₂O₃ nanorods photoelectrochemical deep UV photodetectors

Abstract

Ga₂O₃is a good candidate for deep ultraviolet photodetectors due to its wide-bandgap, good chemical, and thermal stability. Ga₂O₃-based photoelectrochemical (PEC) photodetectors attract increasing attention due to the simple fabrication and self-powered capability, but the corresponding photoresponse is still inferior. In this paper, the oxygen vacancy (V_o) engineering towards<i>α</i>-Ga₂O₃was proposed to obtain high-performance PEC photodetectors. The<i>α</i>-Ga₂O₃nanorods were synthesized by a simple hydrothermal method with an annealing process. The final samples were named as Ga₂O₃-400, Ga₂O₃-500, and Ga₂O₃-600 for annealing at 400 ℃, 500 ℃, and 600 ℃, respectively. Different annealing temperatures lead to different V_oconcentrations in the<i>α</i>-Ga₂O₃nanorods. The responsivity is 101.5 mA W^-1for Ga₂O₃-400 nanorod film-based PEC photodetectors under 254 nm illumination, which is 1.4 and 4.0 times higher than those of Ga₂O₃-500 and Ga₂O₃-600 nanorod film-based PEC photodetectors, respectively. The photoresponse of<i>α</i>-Ga₂O₃nanorod film-based PEC photodetectors strongly depends on the V_oconcentration and high V_oconcentration accelerates the interfacial carrier transfer of Ga₂O₃-400, enhancing the photoresponse of Ga₂O₃-400 nanorod film-based PEC photodetectors. Furthermore, the<i>α</i>-Ga₂O₃nanorod film-based PEC photodetectors have good multicycle, long-term stability, and repeatability. Our result shows that<i>α</i>-Ga₂O₃nanorods have promising applications in deep UV photodetectors.