Demonstration of a 4.32 μm cutoff InAsSbBi nBn photodetector, a lattice-matched random alloy III-V solution for mid-wave infrared sensing

InAsSbBi nBn photodetectors are demonstrated that are lattice-matched to the underlying GaSb substrate with a 4.32 μm wavelength cutoff at 150 K that is 0.3 μm longer than that of lattice-matched InAsSb at this temperature reflecting a 0.5% Bi mole fraction in the InAsSbBi active region. A low growth temperature was utilized to facilitate the incorporation of Bi, resulting in a minority carrier lifetime on the order of 24 ns in the InAsSbBi active region. Nevertheless, the detectors exhibit a quantum efficiency of 17% at 3.3 μm wavelength with a dark current density of 50 μA/cm² at 150 K and −0.4 V bias and the strong photoresponse turn-on characteristic of a random alloy at 4.32 μm wavelength and 150 K. A shot noise-equivalent irradiance analysis indicates that this detectors' dark-current-limited noise-equivalent irradiance of 10¹² cm⁻² s⁻¹ is two orders of magnitude greater than the Rule 07 expectation for this cutoff, and dark-current-limited shot noise-equivalent irradiance performance transitions to photon-limited at 1.7 × 10¹⁵ photons/cm² s.