Oxygen-vacancy-dependent high-performance α-Ga2O3 nanorods photoelectrochemical deep UV photodetectors

Abstract

Ga2O3 is 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 (Vo) engineering towards α-Ga2O3 was proposed to obtain high-performance PEC photodetectors. The α-Ga2O3 nanorods 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 Vo concentrations in the α-Ga2O3 nanorods. The responsivity is 101.5 mA W−1 for 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 α-Ga2O3 nanorod film-based PEC photodetectors strongly depends on the Vo concentration and high Vo concentration accelerates the interfacial carrier transfer of Ga2O3-400, enhancing the photoresponse of Ga2O3-400 nanorod film-based PEC photodetectors. Furthermore, the α-Ga2O3 nanorod film-based PEC photodetectors have good multicycle, long-term stability, and repeatability. Our result shows that α-Ga2O3 nanorods have promising applications in deep UV photodetectors.