Resonant cavity-enhanced photodetector incorporating a type-II superlattice to extend MWIR sensitivity

Mid-infrared resonant cavity-enhanced photodetectors (RCE PD) present a promising technology for targeted gas detection. We demonstrate an RCE PD incorporating an InAs/InAsSb superlattice as the detecting element, extending the resonant wavelength beyond 4 µm. AlAsSb/GaSb mirrors and a unipolar barrier active region paralleling an nBn structure are also used, and performance is compared to a conventional broadband nBn detector incorporating the same superlattice. The RCE PD exhibited a Q-factor of ∼90 and an extremely stable resonance wavelength. Peak responsivity was 3.0 A W^-1 at 240 K, equalling 84% quantum efficiency, a 5.5 times increase over the reference nBn at the same wavelength. Dark current density was 3.3×10^-2 A cm^-2 at 240 K, falling to 2.7×10^-4 A cm^-2 at 180 K. The broadband BLIP limit is approached at 180 K with specific detectivity of 2.1×10¹¹ cm Hz^1/2 W^-1, which presents the potential of achieving BLIP-limited operation in the thermoelectric cooling regime.