Long-wave infrared nBn photodetectors based on InAs/InAsSb type-II superlattices

Long-wave infrared InAs/InAsSb type-II superlattice nBn photodetectors are demonstrated on GaSb substrates. The typical device consists of a 2.2 μm thick absorber layer and has a 50% cutoff wavelength of 13.2 μm, a measured dark current density of 5 × 10−4 A/cm2 at 77 K under a bias of −0.3 V, a peak responsivity of 0.24 A/W at 12 μm, and a maximum resistance-area product of 300 Ω cm2 at 77 K. The calculated generation-recombination noise limited specific detectivity (D*) and experimentally measured D* at 12 μm and 77 K are 1 × 1010 cm Hz1/2/W and 1 × 108 cm Hz1/2/W, respectively.