Under-Seawater Immersion β-Ga 2 O 3 Solar-Blind Ultraviolet Imaging Photodetector with High Photo-to-Dark Current Ratio and Fast Response.

This work displays a photovoltaic solar-blind UV photodetector based on a β-Ga 2 O 3 photoelectrode/simulated seawater (NaCl). The photodetector exhibits extremely high photocurrent (6.70 μA); the responsivity can reach 23.47 mA W -1 , and the fastest response rise time is 40 ms under 213 nm illumination at zero bias, the responsivity is 25.10 mA W -1 at 0.8 V, and the photo-to-dark current ratio reaches a maximum of 4663, whose responsivity can be effectively adjusted by changing electrolyte concentration, ensuring a good working stability of this device. In addition, with original seawater as the electrolyte, the detector still achieves a high switching ratio (754) and stable detection under zero bias, demonstrating its capability for practical uses. What's more, we present the capability of the photodetector in seawater imaging. This work provides a method for solar-blind UV detection in seawater, which compensates for the limited detection of most current seawater detectors in the visible band, and can provide certain guidance in the field of seawater detection.