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

Abstract

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/spl times/486 format monolithically integrated 8-9 and 14-15 /spl mu/m two-color (or dual wavelength) QWIP focal plane arrays (FPAs). These FPAs were then hybridized to 640/spl times/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 /spl 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 /spl 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/spl Delta/T), uniformity, and operability.