[en] An InAsSb nBn detector structure was grown on both GaAs and native GaSb substrates. Temperature dependent dark current, spectral response, specific detectivity $(D\ast <!--\; ???\; -->)$ and noise spectral density measurements were then carried out. Shot-noise-limited $D\ast <!--\; ???\; -->$figures of $1.2\times <!--\; ??\; -->{10}^{10}\mathrm{J}\mathrm{o}\mathrm{n}\mathrm{e}\mathrm{s}$ and $3.0\times <!--\; ??\; -->{10}^{10}\mathrm{J}\mathrm{o}\mathrm{n}\mathrm{e}\mathrm{s}$ were calculated (based upon the sum of dark current and background photocurrent) for the sample grown on GaAs and the sample grown on GaSb, respectively, at 200 K. Noise spectral density measurements revealed knee frequencies of between 124–337 Hz and ∼8 Hz, respectively. Significantly, these devices could support focal plane arrays capable of operating under thermoelectric cooling. (paper)