The paper reports on the barrier mid-wave infrared InAs/InAsSb (x_Sb = 0.4) type-II superlattice detector operating below thermoelectrical cooling. AlAsSb with Sb composition, x_Sb = 0.97; barrier doping, N_D < 2×10¹⁶ cm⁻³ leading to valence band offset below 100 meV in relation to the active layer doping, N_D = 5×10¹⁵ cm⁻³ was proved to be proper material not introducing extra barrier in valence band in the analyzed temperature range in XBn architectures. The detectivity of the simulated structure was assessed at the level of ∼ 10¹¹ Jones at T ∼ 100 K assuming absorber thickness, d = 3 μm. The detector’s architecture for high frequency response operation, τ_s = 420 ps (T ∼ 77 K) was presented with a reduced active layer of d = 1 μm.