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24 August 2005 Two-color infrared focal plane array based on InAs/InGaAs/GaAs quantum dots in a well detectors design
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We report the first two-color 320 x 256 infrared Focal Plane Array (FPA), based on a voltage-tunable InAs/InGaAs/GaAs DWELL structure. The detectors, grown by solid source molecular beam epitaxy (MBE) comprise of a 15-stack asymmetric DWELL structure sandwiched between two highly doped n-GaAs contact layers, grown on a semi-insulating GaAs substrate. The DWELL region consists of a 2.2 monolayer deposition of n-doped InAs quantum dots (QDs) in an In0.15GaAs0.85As well, itself placed in GaAs. The well widths below and above the dots are 50Å and 60Å, respectively. The absorption region asymmetry results in a bias dependent spectral response, with the peak wavelength varying from 5.5 to 10 μm. Using calibrated black body measurements, mid-wavelength and long wavelength specific detectivities (D*) of top-illuminated test pixels at 78K were estimated to be 7.1 x 1010 cmHz1/2/W (Vb= 1.0V) and 2.8 x 1010 cmHz1/2/W (Vb= 2.5V), respectively. Subsequently, a 320 x 256 QDIP FPA array was fabricated on a 30 μm pitch and was hybridized with an Indigo 9705 ROIC. Thermal imaging was successfully carried out at an estimated FPA temperature of 80K, using different optical filters between 3-5 μm, and 8-12 μm, so as to demonstrate two-color operation. The operability of the FPA was greater than 99%, and the noise-equivalent temperature difference was estimated to be less than 100 mK for f#1 (3-5 μm) and f#2 (5-9 μm) optics.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Senthil Annamalai, Philip Dowd, Darren Forman, Petros Varangis, Tom Tumolillo, Allen Gray, Kathy Sun, Mingguo Liu, Joe Campbell, Daniel Carothers, and Sanjay Krishna "Two-color infrared focal plane array based on InAs/InGaAs/GaAs quantum dots in a well detectors design", Proc. SPIE 5897, Photonics for Space Environments X, 58970P (24 August 2005);


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