Oxygen-vacancy-dependent high-performance α -Ga 2 O 3 nanorods photoelectrochemical deep UV photodetectors.

Ga 2 O 3 is a good candidate for deep ultraviolet photodetectors due to its wide-bandgap, good chemical, and thermal stability. Ga 2 O 3 -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 α -Ga 2 O 3 was proposed to obtain high-performance PEC photodetectors. The α -Ga 2 O 3 nanorods were synthesized by a simple hydrothermal method with an annealing process. The final samples were named as Ga 2 O 3 -400, Ga 2 O 3 -500, and Ga 2 O 3 -600 for annealing at 400 ℃, 500 ℃, and 600 ℃, respectively. Different annealing temperatures lead to different V o concentrations in the α -Ga 2 O 3 nanorods. The responsivity is 101.5 mA W -1 for Ga 2 O 3 -400 nanorod film-based PEC photodetectors under 254 nm illumination, which is 1.4 and 4.0 times higher than those of Ga 2 O 3 -500 and Ga 2 O 3 -600 nanorod film-based PEC photodetectors, respectively. The photoresponse of α -Ga 2 O 3 nanorod film-based PEC photodetectors strongly depends on the V o concentration and high V o concentration accelerates the interfacial carrier transfer of Ga 2 O 3 -400, enhancing the photoresponse of Ga 2 O 3 -400 nanorod film-based PEC photodetectors. Furthermore, the α -Ga 2 O 3 nanorod film-based PEC photodetectors have good multicycle, long-term stability, and repeatability. Our result shows that α -Ga 2 O 3 nanorods have promising applications in deep UV photodetectors.