High-Detectivity β-Ga₂O₃ Microflake Solar-Blind Phototransistor for Weak Light Detection

This letter reports a high-performance solar-blind phototransistor based on N 2 -annealed \beta -Ga 2 O 3 microflake for weak light detection. The phototransistor exhibits an ultra-low dark current of 27 fA, a high external quantum efficiency of 8.36\times 10^{7} %, a photo-to-dark-current ratio of 1.08\times 10 ^{7} , a low power consumption of 2.92 pW, and a narrow-band response with a cut off wavelength of 263 nm. In addition, the spectral selectivity can be well modulated by the gate bias and reaches a maximum {R} _{240}/{R} _{400} ratio of 2.4\times 10 ^{4} . Especially, an ultra-high responsivity ( {R} ) of 1.71\times 10^{5} A/W and a record-high detectivity ( {D} ^{\ast } ) of 1.19\times 10^{18} Jones have been achieved under 254nm illumination of 4.1~\mu \text{W} /cm 2 . The superior weak-light-detection performance of the device makes it one of the best Ga 2 O 3 detectors towards solar-blind photodetection application.