A versatile dual-band detector capable of active and passive use is demonstrated using short-wave (SW) and midwave (MW) IR type-II superlattice photodiodes. A bilayer etch-stop scheme is introduced for back-side-illuminated detectors, which enhanced the external quantum efficiency both in the SWIR and MWIR spectral regions. Temperature-dependent dark current measurements of pixel-sized 27 μm detectors found the dark current density to be ̃1 × 10-5 A/cm2 for the ̃4.2 μm cutoff MWIR channel at 140 K. This corresponded to a reasonable imager noise equivalent difference in temperature of ̃49 mK using F/2.3 optics and a 10 ms integration time (tint), which lowered to ̃13 mK at 110 K using tint = 30 ms, illustrating the potential for high-temperature operation. The SWIR channel was found to be limited by readout noise below 150 K. Excellent imagery from the dual-band imager exemplifying pixel coincidence is shown.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics