Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices with an AlAsSb/GaSb superlattice barrier

Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices on GaSb substrate have been demonstrated. An AlAs0.10Sb0.90/GaSb H-structure superlattice design was used as the large-bandgap electron-barrier in these photodetectors. The photodetector is designed to have a 100% cut-off wavelength of ∼2.8 μm at 300 K. The photodetector exhibited a room-temperature (300 K) peak responsivity of 0.65 A/W at 1.9 μm, corresponding to a quantum efficiency of 41% at zero bias under front-side illumination, without any anti-reflection coating. With an R × A of 78 Ω·cm2 and a dark current density of 8 × 10−3 A/cm2 under −400 mV applied bias at 300 K, the nBn photodetector exhibited a specific detectivity of 1.51 × 1010 cm·Hz1/2/W. At 150 K, the photodetector exhibited a dark current density of 9.5 × 10−9 A/cm2 and a quantum efficiency of 50%, resulting in a detectivity of 1.12 × 1013 cm·Hz1/2/W.