Mid wavelength infrared InAsSb/InSb nBn detector with extended cut off wavelength
We extended the cut off wavelength lc of bulk InAsSb nBn detectors to lc 4.6 mm at T 200 K by incorporating series of single InSb monolayer into InAsSb absorber. Detectors with 2 mm 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 x 10 6 A/cm2 at T 150 K, and increased to jd 2 x 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*(l) 3 6 x 1011 cm Hz0.5/W for the background temperature of 300 K, and f/2 field of view.