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Advances in III-V semiconductor infrared absorbers and detectors
摘要： Advances in bulk III-V semiconductor material such as InGaAsSb and metamorphic InAsSb, as well as in a variety of type-II superlattices such as InGaAs/GaAsSb, InAs/GaSb, and InAs/InAsSb, have provided continuously adjustable cutoff wavelength coverage from the short to the very long wavelength infrared. We perform basic theoretical analysis to provide comparisons of different infrared materials. We also briefly report experimental results on a mid-wavelength InAs/InAsSb type-II superlattice unipolar barrier infrared detector and a focal plane array with significantly higher operating temperature than InSb.
关键词： unipolar barrier,MWIR,infrared detector,e-SWIR,LWIR,antimonide,type-II superlattice,nBn,effective mass
更新于2025-09-23 15:23:52
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Minority carrier lifetime and diffusion length in type II superlattice barrier devices
摘要： The minority carrier lifetime in p-type InAs/GaSb type II superlattices (T2SLs) is quite short, typically in the region of tens of nanoseconds. In spite of this, T2SLs are becoming a viable alternative to Mercury Cadmium Telluride as the sensing material of choice for high end MWIR and LWIR infrared detectors. For example, SCD now manufactures a 640 × 512 format, 15 μm pitch LWIR focal plane array detector, with a quantum e?ciency close to 50%, a pixel operability of > 99.5%, and a dark current only about one order of magnitude larger than the state of the art Rule 07 value. A key to the very high performance of this detector is the use of an XBp barrier architecture that both suppresses the G-R current and allows stable passivation to all steps of the fabrication process. Since both the dark-current and photo-current in the XBp structure are di?usion limited, measurements of these quantities as a function of the device dimension provide an excellent vehicle for estimating the minority carrier lifetime and di?usion length, when performed in conjunction with k?p calculations of the T2SL density of states. Typical lifetime results are presented, which are consistent with values found by others using direct measurements. Di?usion lengths are reported in the range 3–7 μm, although these are not necessary limiting values.
关键词： Type II superlattice,Infrared detector,XBp detector,Di?usion length,InAs/GaSb superlattice,K?p model,Lifetime,Bariode
更新于2025-09-23 15:21:01
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A comparison of mechanisms for improving dark current characteristics in barrier infrared photodetectors
摘要： The dark current characteristics in InAs/GaSb type-II superlattice (SL) barrier infrared photodetectors are theoretically investigated using the drift-diffusion-based device simulator. It is shown that both structures can effectively reduce the dark current compared to the p-i-n photodiode without barrier, and the dependence on the barrier doping density are discussed in detail. There exists an optimum doping density to minimize the dark current in active region (n type), for which two different engineered structures, i.e., called pBn and nBn, are evaluated.
关键词： dark current,pBn,InAs/GaSb type-II superlattice,barrier infrared photodetectors,nBn
更新于2025-09-23 15:19:57
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Carrier reduction studies of type-II superlattice materials for very long wavelength infrared sensing
摘要： There are continuing efforts to develop type-II superlattice (SL) materials for very long wavelength infrared (VLWIR) detector applications. However, the SLs have high residual electron background doping densities that depend on SL growth conditions, which lead to shorter minority carrier lifetime and lower performance parameters than theoretically predicted. In this study, the authors compare the technical advantages of using InAs/GaInSb over InAs/GaSb SL with respect to reducing the electron doping levels. Our temperature-dependent electrical transport measurements show that the InAs/GaInSb SL design has a lower electron density than the InAs/GaSb SL with the same bandgap and have electron densities (mobilities) on the order of the mid 1011 cm?2 (25 000 cm2/V s). Since small period InAs/GaInSb SLs also produce greater Auger recombination suppression for a given VLWIR gap than the large period InAs/GaSb SL, the InAs/GaInSb SL appears to be a better candidate for long lifetime IR materials for future very long wavelength infrared devices.
关键词： very long wavelength infrared,mobility,InAs/GaSb,Auger recombination,InAs/GaInSb,type-II superlattice,carrier reduction,electron doping
更新于2025-09-19 17:15:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - High Dynamic Range Infrared Sensors for Remote Sensing Applications
摘要： In this presentation, we will report our recent efforts in achieving high performance in Antimonides type-II superlattice (T2SL) based infrared photodetectors using the barrier infrared detector (BIRD) architecture. The recent emergence of barrier infrared detectors such as the nBn [1] and the XBn [2] have resulted in mid-wave infrared (MWIR) and long-wave infrared (LWIR) detectors with substantially higher operating temperatures than previously available in III-V semiconductor based MWIR and LWIR detectors. The initial nBn devices used either InAs absorber grown on InAs substrate, or lattice-matched InAsSb alloy grown on GaSb substrate, with cutoff wavelengths of ~3.2 μm and ~4 μm, respectively. While these detectors could operate at much higher temperatures than existing MWIR detectors based on InSb, their spectral responses do not cover the full (3 – 5.5 μm) MWIR atmospheric transmission window. There also have been nBn detectors based on the InAs/GaSb T2SL absorber [3,4].
关键词： infrared detector,focal plane array,type-II superlattice,high dynamic range,high quantum efficiency
更新于2025-09-10 09:29:36
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Electronic band structure of InAs/InAsSb type-II superlattice for HOT LWIR detectors
摘要： The InAs/InAs1?xSbx type-II superlattices (T2SLs) grown on GaSb bu?er layer and GaAs substrates have recently been applied for detectors for long wavelength infrared (LWIR) range and high operating temperature (HOT) conditions. The detailed modeling of T2SLs minibands structure required for detector’s design optimization process relies on accurate knowledge of the InAs1?xSbx bandgap and band edge position. The k?p (8 × 8 method) was used to analyze the valence band o?set (VBO) between InAs and InAs1?xSbx, and hence the InAs1?xSbx band edge position at required xSb composition. An increase of the VBO leads to the structure transformation from type-IIb to type-II superlattices. The required energy bandgap can be reached by changing the conduction band o?set (CBO) and the energy bandgap bowing parameter. The temperature dependence of the experimental results of InAs/InAs1?xSbx T2SLs energy bandgap was found to be comparable with theoretical one when energy bandgap bowing parameter is dependent on temperature. The proper ?tting of theoretically calculated and experimentally measured spectral response characteristics was shown.
关键词： Energy-band o?set,InAs/InAs1?xSbx type-II superlattice,T2SLs,LWIR,Infrared detectors
更新于2025-09-04 15:30:14
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InAs/InAsSb Type-II Superlattice Mid-Wavelength Infrared Focal Plane Array With Significantly Higher Operating Temperature Than InSb
摘要： We report focal plane array (FPA) results on a mid-wavelength InAs/InAsSb type-II strained layer superlattice (T2SLS) unipolar barrier infrared detector with a cutoff wavelength of 5.4 μm. For 300 K background in the 3–5-μm band, f/2 aperture, an FPA operating at 150 K exhibits a mean noise equivalent differential temperature (NEDT) of 18.5 mK, and an NEDT operability of 99.7%. The NE(cid:2)T distribution has a width of 8 mK, with no noticeable distribution tail, indicating excellent uniformity. The mean noise-equivalent irradiance is 9.1 × 1011 photons/sec-cm2. The mean quantum ef?ciency is 49.1% without antire?ection coating, and the mean speci?c detectivity (D?) is 2.53 × 1011 cm-Hz?/W. Bene?tting from an absorber material with a much longer Shockley–Read–Hall minority carrier lifetime, and a device architecture that suppresses generation-recombination and surface-leakage dark current, the InAs/InAsSb T2SLS barrier infrared detector FPA has demonstrated a signi?cantly higher operating temperature than the mid-wavelength infrared market-leading InSb.
关键词： Infrared detector,heterostructure,InAs/InAsSb,type-II superlattice,photodetector,nBn,unipolar barrier,focal plane array
更新于2025-09-04 15:30:14