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

This letter reports a high-performance solar-blind phototransistor based on N2-annealed $\beta $ -Ga2O3 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 $4.1~\mu \text{W}$ /cm2. The superior weak-light-detection performance of the device makes it one of the best Ga2O3 detectors towards solar-blind photodetection application.