Fig. 1. The nBn photodetector: (a) schematic diagram; (b) schematic band structure diagram

Fig. 2. The nBn photodetector at 150 K and -50 mV applied bias: (a) responsivity spectrum; (b) quantum efficiency spectrum：the inset represents the quantum efficiency of the nBn photodetector at 3.82 μm

Fig. 3. The nBn photodetector: (a) dark current density vs. applied bias characteristic at temperatures ranging from 100 K to 300 K; (b) Arrhenius plot of the dark current density under -50 mV applied bias

Fig. 4. The nBn photodetector: (a) specific detectivity spectrum at 150 K and -50 mV applied bias; (b) specific detectivity vs. 1000/T at 3.82 μm：the dotted line shows the BLIP detectivity for an ideal photodetector with 300 K background and 2π field of view