High-performance mid-wavelength infrared InAs/InAsSb nBn detector and focal plane array at 230 K enabling imaging of room-temperature human targets

Abstract

High-performance nBn mid-wavelength infrared (MWIR) photodetectors and focal plane arrays (FPAs) based on an InAs/InAsSb type-II superlattice (T2SL) absorber and an AlSb/AlAsSb T2SL superlattice have been demonstrated. At 150 K, the photodetector exhibits 50% cutoff wavelength of 4.8 μm, a peak responsivity of 1.72 A/W corresponding to a quantum efficiency of 56.9% at an applied bias of −0.1 V, and a dark current density of 1.38 × 10−6 A/cm2, which is 2× Rule 07. The dark current-limited and f/2 blackbody (300 K background, 3–5 μm band) specific detectivities reach 2.55 × 1012 and 3.69 × 1011 cm Hz1/2/W, respectively. A 15 μm pitch, 640 × 512 format nBn FPA fabricated from the same wafer achieves a mean noise equivalent temperature difference of 13.9 mK and an operability of 99.8% at 150 K under f/2 optics. The nBn FPA enables imaging of room-temperature human targets up to 230 K with only two-point nonuniformity correction. This work demonstrates the significant potential of InAs/InAsSb superlattice-based nBn photodetectors and FPAs for thermoelectrically cooled MWIR imaging.