Solar-blind UV photodetectors based on α-Ga₂O₃ prepared by a two-step hydrothermal method

In this study, α-Ga₂O₃ nanorod arrays (NRAs) were grown using a simple and low-cost two-step hydrothermal method. Subsequently, a photoelectrochemical ultraviolet photodetector (PEC-UV PD) based on the α-Ga₂O₃ NRAs was fabricated, which can operate at zero bias and has a performance far superior to that of PEC-UV PDs based on the one-step hydrothermal method. Under 2 mW/cm² illumination at 254 nm, the device achieved a responsivity of 26.59 mA/W, an external quantum efficiency of 12.98%, and a rise/decay time of 53 ms/7 ms without external bias. These results demonstrate outstanding detection performance compared to previously reported devices. The superior performance can be attributed to the better crystallinity which provides a larger absorption area for the device, the solution contact area, and a faster channel for carrier transport, the space charge region at the solid/liquid interface which also allows efficient separation of photogenerated carriers. Furthermore, it also benefits from the positive effects of moderate oxygen vacancy (V_O) concentrations for NRAs. The α-Ga₂O₃ NRAs PEC-UV PD with two-step hydrothermal method is undoubtedly a promising candidate for future solar-blind detection.