Mid-wavelength infrared InAsSb/InSb nBn detector with extended cut-off wavelength

We extended the cut-off wavelength λc of bulk InAsSb nBn detectors to λc = 4.6 μm at T = 200 K by incorporating series of single InSb monolayer into InAsSb absorber. Detectors with 2 μm thick absorber showed a temperature independent quantum efficiency QEm ≈ 0.45 for back-side illumination without antireflection coating. The dark current density was jd = 5 × 10−6 A/cm2 at T = 150 K, and increased to jd = 2 × 10−3 A/cm2 at T = 200 K. At temperatures of T = 150 K and below, the demonstrated photodetectors operate in the background limited performance mode, with detectivity D*(λ) = 3–6 × 1011 cm Hz0.5/W for the background temperature of 300 K, and f/2 field of view.