title: Active and passive infrared imager based on short-wave and mid-wave type-II superlattice dual-band detectors.
abstract: A versatile dual-band detector capable of active and passive use is demonstrated using short-wave (SW) and mid-wave (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/cm(2) 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 (t(int)), which lowered to ~13 mK at 110 K using t(int)=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.
authors.affiliation: Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Edward Kwei-wei
authors.initials: EK
authors.lastname: Huang
authors.forename: Abbas
authors.initials: A
authors.lastname: Haddadi
authors.forename: Guanxi
authors.initials: G
authors.lastname: Chen
authors.forename: Anh-Minh
authors.initials: AM
authors.lastname: Hoang
authors.forename: Manijeh
authors.initials: M
authors.lastname: Razeghi