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 β-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 x 107%, a photo-to-dark-current ratio of 1.08 x 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 x 10 ⁴ . Especially, an ultra-high responsivity (R) of 1.71 x 10 ⁵ A/W and a record-high detectivity (D*) of 1.19 x 10 ¹⁸ Jones have been achieved under 254nm illumination of 4.1 μW/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.