Large-Area α -Ga₂O₃ Metal–Semiconductor– Metal Photodetectors for Detecting Ultralow UV-C Light Amid Sunlight in Arc Monitoring

We developed a high-performance large-area <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha $ </tex-math></inline-formula>-Ga2O3 metal–semiconductor–metal (MSM) photodetector tailored for ultralow intensity light detection. By employing unintentionally doped (UID) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha $ </tex-math></inline-formula>-Ga2O3 thin films and optimizing electrode configurations, the photodetector achieved an ultralow dark current of 0.2 nA/cm2, a high specific detectivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.1\times 10^{{13}}$ </tex-math></inline-formula> Jones, and a fast response time of 0.793 s. To further address challenges such as sub-bandgap photoconductivity and interference from solar background noise, it was integrated with a charge-sensitive amplifier (CSA) circuit, resulting in a substantial improvement in the signal-to-noise ratio (SNR) and detection robustness under direct sunlight. This enabled the detection of a minimum ultralow light intensity of 0.56 nW/cm2 and an arc from a distance of 30 cm under solar illumination.