The nearly lattice-matched InAs/GaSb/AlSb (antimonide) material system offers tremendous
flexibility in realizing high-performance infrared detectors. Antimonide-based superlattice (SL)
detectors can be tailor-made to have cutoff wavelengths ranging from the short wave infrared
(SWIR) to the very long wave infrared (VLWIR). SL detectors are predicted to have suppressed
Auger recombination rates and low interband tunneling, resulting in the suppressed dark currents.
Moreover, the nearly lattice-matched antimonide material system, consisting of InAs, GaSb, AlSb
and their alloys, allows for the construction of superlattice heterostructures. In particular, unipolar
barriers, which blocks one carrier type without impeding the flow of the other, have been
implemented in the design of SL photodetectors to realize complex heterodiodes with improved
performance. Here, we report our recent efforts in achieving state-of-the-art performance in
antimonide superlattice based infrared photodetectors.
Jet Propulsion Laboratory is actively developing the III-V based infrared detector and focal plane arrays (FPAs) for
remote sensing and imaging applications. Currently, we are working on Superlattice detectors, multi-band Quantum
Well Infrared Photodetectors (QWIPs), and Quantum Dot Infrared Photodetector (QDIPs) technologies suitable for
high pixel-pixel uniformity and high pixel operability large area imaging arrays. In this paper, we will discuss the
demonstration of long-wavelength 1Kx1K QDIP FPA, 1Kx1K QWIP FPA, the first demonstration of the megapixelsimultaneously-
readable and pixel-co-registered dual-band QWIP FPA, and demonstration of the first mid-wave and
long-wave 1Kx1K superlattice FPA. In addition, we will discuss the advantages of III-V material system in the context
of large format infrared FPAs.
In this study the material quality and optical properties of type II InAs/GaSb superlattices are investigated using
transmission and photoluminescence (PL) spectroscopy. The influence of the material quality on the intensity of the
luminescence and on the electrical properties of the detectors is studied and a good correlation between the photodetector
current-voltage (IV) characteristics and the PL intensity is observed. Studies of the temperature dependence of the PL
reveal that Shockley-Read-Hall processes are limiting the minority carrier lifetime in both the mid-IR wavelength and
the long-IR wavelength detector material studied. These results demonstrate that PL spectroscopy is a valuable tool for
optimization of infrared detectors.
The nearly lattice-matched InAs/GaSb/AlSb (antimonide) material system offers tremendous flexibility in realizing
high-performance infrared detectors. Antimonide-based alloy and superlattice infrared absorbers can be customized to
have cutoff wavelengths ranging from the short wave infrared (SWIR) to the very long wave infrared (VLWIR). They
can be used in constructing sophisticated heterostructures to enable advanced infrared photodetector designs. In
particular, they facilitate the construction of unipolar barriers, which can block one carrier type but allow the unimpeded
flow of the other. Unipolar barriers are used to implement the barrier infra-red detector (BIRD) design for
increasing the collection efficiency of photo-generated carriers, and reducing dark current generation without impeding
photocurrent flow. We report our recent efforts in achieving state-of-the-art performance in antimonide alloy and
superlattice based infrared photodetectors using the BIRD architecture. Specifically, we report a 10 μm cutoff
superlattice device based on a complementary barrier infrared detector (CBIRD) design. The detector, without antireflection
coating or passivation, exhibits a responsivity of 1.5 A/W and a dark current density of 1×10-5 A/cm2 at 77K
under 0.2 V bias. It reaches 300 K background limited infrared photodetection (BLIP) operation at 87 K, with a blackbody
BLIP D* value of 1.1×1011 cm-Hz1/2/W for f/2 optics under 0.2 V bias.
We have demonstrated the use of bulk antimonide based materials and type-II antimonide
based superlattices in the development large area long wavelength infrared (LWIR) focal
plane arrays (FPAs). Barrier infrared photodetectors (BIRDS) and superlattice-based infrared
photodetectors are expected to outperform traditional III-V MWIR and LWIR imaging
technologies and are expected to offer significant advantages over II-VI material based FPAs.
Our group has developed a novel complementary barrier infrared detector (CBIRD) which
utilizes properties unique to the antimonide material system to incorporate unipolar barriers
on either side of a superlattice absorber region. We have used molecular beam epitaxy
(MBE) technology to grow InAs/GaSb CBIRD structures on large area 100mm GaSb
substrates with excellent results. Furthermore, we have fabricated initial 1024x1024 pixels
superlattice imaging FPAs based on the CBIRD concept.
Unipolar barriers can block one carrier type but allow the un-impeded flow of the other. They can be used to implement the barrier
infra-red detector (BIRD) design for increasing the collection efficiency of photo-generated carriers, and reducing dark current generation without impeding photocurrent flow. In particular, the InAs/GaSb/AlSb material system, which can be epitaxially grown on GaSb or InAs substrates, is well suited for implementing BIRD structures, as there is considerable flexibility in forming a variety of alloys and superlattices, and tailoring band offsets. We describe our efforts to achieve high-performance long wavelength InAs/GaSb superlattice infrared photodetectors based on the BIRD architecture. Specifically, we report a 10 μm cutoff device based on a complementary barrier infrared detector (CBIRD) design. The detector, without anti-reflection coating, exhibits a responsivity of 1.5 A/W and a dark current density of 1×10-5 A/cm2 at 77K under 0.2 V bias. It reaches 300 K background limited infrared photodetection (BLIP) operation at 101 K, with a black-body BLIP D* value of 2.6×1010 cm-Hz1/2/W for 2π field of view under 0.2 V bias.
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