High quantum efficiency long-/long-wave dual-color type-II InAs/GaSb infrared detector

A long-/long-wave dual-color detector with N-M-pi-B-pi-M-N structure was developed based on a type-II InAs/GaSb superlattice. The saturated responsivity was achieved under low bias voltage for both channels. The device could be operated as a single detector for sequential detection and showed high quantum efficiencies. The peak quantum efficiencies of long-wavelength infrared band-1 (blue channel) and long-wavelength infrared band-2 (red channel) were 44% at 6.3 mu m under 20 mV and 57% at 9.1 mu m under -60 mV, respectively. The optical performance for each channel was achieved using a 2 mu m thickness absorber. Due to the high QE, the specific detectivities of the blue and red channels reached 5.0 x 10(11) cm.Hz(1/2)/W at 6.8 mu m and 3.1 x 10(11) cm.Hz(1/2)/W at 9.1 mu m, respectively, at 77 K.