The carrier lifetimes determined by radiative and Auger 1 recombination in InAs_1-xSb_x were calculated at different temperatures. For n-type InAsSb material， at low temperatures， the carrier lifetime is limited by the radiative recombination， while at high temperatures， the Auger 1 process is dominant. An analytical model of dark current for barrier blocking detectors was discussed， by adding a heavily doped n-type InAsSb electrode on the other side of the absorber layer to form an nBnn⁺ structure to deplete the carriers in absorber， the hole concentration in absorption region was decreased about two orders of magnitude， further reducing the dark current of the devices. InAsSb-based nBnn⁺ barrier devices have been successfully fabricated and characterized. At 150 K， the devices displayed a dark current density as low as 3×10^-6 A/cm²， the dark current density of the detectors was fitted by the nBn-based architecture analytical current model， the experimental results indicated that due to the p-type doping of the barrier layer， a depletion region was formed in the InAsSb absorber region， resulting in incomplete inhibition of G-R current. At temperatures below 180 K， the dark current of the detector is limited by G-R process， at temperatures above 180 K， the dark current of the device is limited by diffusion current.