Hole diffusion length and mobility of a long wavelength infrared InAs/InAsSb type-II superlattice nBn design

We report results from an 8.9 m cutoff InAs/InAsSb type-II strained-layer superlattice (T2SLS) nBn detector. The measured minority carrier (hole) lifetime is  =1.2 s at 80K. The detector quantum efficiency is 40 % for back side illuminated devices without antireflection coating. The dark current density at turn-on bias is 1.0×10-8 A/cm2 at 50 K and 4.6×10-6 A/cm2 at 80 K. We investigated the minority carrier (hole) lifetime and responsivity, from which we found the temperature dependence of minority carrier (hole) diffusion length and mobility. The hole diffusion length and mobility, respectively, are 1.3 m and, 6.5 cm2/Vs at 30 K, and increase to 6.5 m and 36 cm2/Vs at T = 90 K. We compare the long-wavelength infrared T2SLS diffusion length and mobility with these of a mid-wavelength infrared T2SL and discussed the hole transport properties in these devices.