640 x 486 long-wavelength two-color GaAs/AlGaAs quantum well infrared photodetector (QWIP) focal plane array camera

We have designed and fabricated an optimized long-wavelength/very-long-wavelength two-color quantum well infrared photodetector (QWIP) device structure. The device structure was grown on a 3-in semi-insulating GaAs substrate by molecular beam epitaxy (MBE), The wafer was processed into several 640 x 486 format monolithically integrated 8-9 and 14-15 mu m two-color (or dual wavelength) QWIP focal plane arrays (FPA's), These FPA's were then hybridized to 640 x 486 silicon CMOS readout multiplexers. A thinned (i.e,, substrate removed) FPA hybrid was integrated into a liquid helium cooled dewar for electrical and optical characterization and to demonstrate simultaneous two-color imagery. The 8-9 mu m detectors in the FPA have shown background limited performance (BLIP) at 70 K operating temperature for 300 K background with f/2 cold stop. The 14-15 mu m detectors of the FPA reaches BLIP at 40 K operating temperature under the same background conditions. In this paper we discuss the performance of this long-wavelength dualband QWIP FPA in terms of quantum efficiency, detectivity, noise equivalent temperature difference (NE Delta T), uniformity, and operability.