Fig. 1. Fabrication process of Ge：B BIB detector

Fig. 2. Doping profile of B in the absorbing region by five-steps-implantation

Fig. 3. Three-dimensional（3-D）schematic structure of Ge：B BIB detector

Fig. 4. Dark current of Ge：B BIB detector at different temperatures

Fig. 5. Responsivity in response to a 1000 K blackbody at 3.5 K

Fig. 6. Relative spectral response at 3.5 K

Fig. 7. Two excitation models in Ge：B BIB detector

Fig. 8. Normalized spectral response at different voltages at 3.5 K，and the inset is the ratio of the relative response intensity at 40 mV and 10 mV