We report InAs/InAs1-xSbx type-II superlattice base photodetector as high performance long-wavelength infrared nBn device grown on GaSb substrate. The device has 6 μm-thick absorption region, and shows optical performance with a peak responsivity of 4.47 A/W at 7.9 μm, which is corresponding to the quantum efficiency of 54% at a bias voltage of negative 90 mV, where no anti-reflection coating was used for front-side illumination. At 77K, the photodetector's 50% cut-off wavelength was ∼10 μm. The device shows the detectivity of 2.8x1011 cm.√Hz/W at 77 K, where RxA and dark current density were 119 Ω•cm2 and 4.4x10-4 A/cm2, respectively, under-90 mV applied bias voltage. © 2016 SPIE.