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Sanjay Krishna - One of the best experts on this subject based on the ideXlab platform.
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modeling and extraction of optical characteristics of inas gasb strained Layer Superlattice
Infrared Technology and Applications XLVI, 2020Co-Authors: Nicole Pfiester, Jordan Budhu, Seung Hyun Lee, Vinita Dahiya, Kwongkit Choi, C D Ball, Steve M Young, Anthony Grbic, Sanjay KrishnaAbstract:With the increasing use of resonant structures in optical devices, broadband optical characterization of the refractive index and extinction coefficient is necessary for accurate simulation and device design. For resonance-enhanced photodetectors, the complex refractive index is necessary to impedance match not only the resonator to air, minimizing the reflection, but also the resonator to the detector element, ensuring absorption occurs in the photodiode. To work towards better resonator-detector coupling, we present the complex refractive index for GaSb and an InAs/GaSb strained Layer Superlattice designed to be the absorber Layer for a long-wave infrared photodetector. The optical properties were extracted using spectroscopic ellipsometry. Several modeling methods will be discussed for both the Superlattice and the single-side polished bulk GaSb. Comparison to transmission and reflection values as well as absorption coefficients from literature provide additional confidence in the extraction process. Future work will incorporate these values into a resonance-enhanced photodetector.
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impact of temperature and gamma radiation on electron diffusion length and mobility in p type inas gasb Superlattices
Journal of Applied Physics, 2018Co-Authors: Jonathan Lee, Sanjay Krishna, Leonid Chernyak, Chris J Fredricksen, Elena Flitsiyan, Robert E Peale, Zahra Taghipour, Lilian K Casias, Alireza Kazemi, S MyersAbstract:The minority carrier diffusion length was directly measured by the variable-temperature Electron Beam-Induced Current technique in InAs/GaSb type-II strain-Layer-Superlattice infrared-detector structures. The Molecular Beam Epitaxy-grown midwave infrared Superlattices comprised 10 monoLayers of InAs and 10 monoLayers of GaSb to give a total absorber thickness of 4 μm. The diffusion length of minority electrons in the p-type absorber region of the p-type/barrier/n-type structure was found to increase from 1.08 to 2.24 μm with a thermal activation energy of 13.1 meV for temperatures ranging from 77 to 273 K. These lengths significantly exceed the individual 10-monoLayer thicknesses of the InAs and GaSb, possibly indicating a low impact of interface scattering on the minority carrier diffusion length. The corresponding minority electron mobility varied from 48 to 65 cm2/V s. An absorbed gamma irradiation dose of 500 Gy halved the minority carrier diffusion length and increased the thermal activation energy to 18.6 meV, due to creation of radiation-induced defect recombination centers.
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comparison of mwir unipolar barrier structures based on strained Layer Superlattices conference presentation
Proceedings of SPIE, 2016Co-Authors: David A. Ramirez, Christian P. Morath, S Myers, Elizabeth H Steenbergen, Yuliya Kuznetsova, Sen Mathews, T Schulersandy, Vicent M Cowan, Sanjay KrishnaAbstract:In this work, we compare the performance of three MWIR unipolar barrier structures based on the InAs/GaSb Type-2 strained Layer Superlattice material system. We have designed, fabricated, and characterized pBiBn, pBn, and pBp detector structures. All the structures have been designed so that the cut off wavelength is around 5 microns at 100 K. We fabricated single-pixel devices and characterize their radiometric performance. In addition, we have characterized the degradation of the performance of the devices after exposing the devices to 63 MeV proton radiation to total ionizing dose of 100 kRad (Si). In this report, we compare the performance of the different structures with the objective of determining the advantages and disadvantages of the different designs. This work was supported by the Small Business Innovation Research (SBIR) program under the contract FA9453-14-C-0032, sponsored by the Air Force Research Laboratory (AFRL).
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dual color longwave inas gasb type ii strained Layer Superlattice detectors
Infrared Physics & Technology, 2015Co-Authors: Elena Plis, David A. Ramirez, S Myers, E P G Smith, David R Rhiger, Chihyu Chen, J D Phillips, Sanjay KrishnaAbstract:Abstract We report on the design, growth, fabrication and characterization of dual-band (long-/long-wave infrared) type-II InAs/GaSb strained Layer Superlattice (T2SL) detectors with pBp architecture. Under operating the bias of −200 mV and +100 mV, quantum efficiencies of 37% (∼11 μm band) and 25% (∼9 μm band) were realized, respectively. To reduce the dark current in a dual-band T2SL detector, the effect of a “restoration” chemical etch treatment and ZnTe passivation on device performance were investigated.
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carrier lifetime studies in midwave infrared type ii inas gasb strained Layer Superlattice
Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials Processing Measurement and Phenomena, 2014Co-Authors: B Klein, Elena Plis, Thomas J Rotter, Sanjay Krishna, N Gautam, Ted Schulersandy, Blair C Connelly, Grace D Metcalfe, Paul H Shen, Michael WrabackAbstract:The authors report on an investigation of the dependence of the minority carrier lifetime in midwave infrared InAs/GaSb strained Layer Superlattices on a number of varied parameters: Layer placement of two dopants (either Be or Te), and interface treatment between InAs and GaSb Layers. In samples where the dopant and doping location was varied, it was found that the nonintentionally doped control sample exhibited the longest lifetimes (∼49 ns at 77 K under low injection), followed by the Be-doped and the Te-doped samples. Regardless of the type of doping, samples with dopants in only the InAs Layer appeared to have longer lifetimes [low injection: 15 ns (Be), <3 ns (Te); high injection: 38 ns (Be), 16.2 ns (Te) at 77 K] compared to samples with dopants in the GaSb Layer or all Layers. However, because trap saturation behavior was observed in the transient photoluminescence (PL) decay, the intensity-dependent PL lifetime is a function of both the minority and majority carrier lifetimes, complicating the interpretation of the data. In samples where the treatment of the InAs/GaSb interface was varied, the sample that demonstrated the longest lifetime had a one-period growth sequence of InAs, an Sb soak, GaSb, and an InSb strain compensation Layer. Of the three interface samples investigated, the sample (with a growth sequence of InAs, an Sb soak, GaSb, and a growth interrupt) that demonstrated the shortest lifetime also exhibited a fast initial decay for all injection levels, at only 110 and 150 K. This fast initial decay has been attributed to the appearance of another Shockley–Read–Hall trap level, contributing to a shorter carrier lifetime.
Elena Plis - One of the best experts on this subject based on the ideXlab platform.
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dual color longwave inas gasb type ii strained Layer Superlattice detectors
Infrared Physics & Technology, 2015Co-Authors: Elena Plis, David A. Ramirez, S Myers, E P G Smith, David R Rhiger, Chihyu Chen, J D Phillips, Sanjay KrishnaAbstract:Abstract We report on the design, growth, fabrication and characterization of dual-band (long-/long-wave infrared) type-II InAs/GaSb strained Layer Superlattice (T2SL) detectors with pBp architecture. Under operating the bias of −200 mV and +100 mV, quantum efficiencies of 37% (∼11 μm band) and 25% (∼9 μm band) were realized, respectively. To reduce the dark current in a dual-band T2SL detector, the effect of a “restoration” chemical etch treatment and ZnTe passivation on device performance were investigated.
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carrier lifetime studies in midwave infrared type ii inas gasb strained Layer Superlattice
Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials Processing Measurement and Phenomena, 2014Co-Authors: B Klein, Elena Plis, Thomas J Rotter, Sanjay Krishna, N Gautam, Ted Schulersandy, Blair C Connelly, Grace D Metcalfe, Paul H Shen, Michael WrabackAbstract:The authors report on an investigation of the dependence of the minority carrier lifetime in midwave infrared InAs/GaSb strained Layer Superlattices on a number of varied parameters: Layer placement of two dopants (either Be or Te), and interface treatment between InAs and GaSb Layers. In samples where the dopant and doping location was varied, it was found that the nonintentionally doped control sample exhibited the longest lifetimes (∼49 ns at 77 K under low injection), followed by the Be-doped and the Te-doped samples. Regardless of the type of doping, samples with dopants in only the InAs Layer appeared to have longer lifetimes [low injection: 15 ns (Be), <3 ns (Te); high injection: 38 ns (Be), 16.2 ns (Te) at 77 K] compared to samples with dopants in the GaSb Layer or all Layers. However, because trap saturation behavior was observed in the transient photoluminescence (PL) decay, the intensity-dependent PL lifetime is a function of both the minority and majority carrier lifetimes, complicating the interpretation of the data. In samples where the treatment of the InAs/GaSb interface was varied, the sample that demonstrated the longest lifetime had a one-period growth sequence of InAs, an Sb soak, GaSb, and an InSb strain compensation Layer. Of the three interface samples investigated, the sample (with a growth sequence of InAs, an Sb soak, GaSb, and a growth interrupt) that demonstrated the shortest lifetime also exhibited a fast initial decay for all injection levels, at only 110 and 150 K. This fast initial decay has been attributed to the appearance of another Shockley–Read–Hall trap level, contributing to a shorter carrier lifetime.
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passivation techniques for inas gasb strained Layer Superlattice detectors
Laser & Photonics Reviews, 2013Co-Authors: Elena Plis, M N Kutty, Sanjay KrishnaAbstract:InAs/(In,Ga)Sb Strained Layer Superlattices (SLSs) have made significant progress since they were first proposed as an infrared (IR) sensing material more than three decades ago. The basic material properties of SLS provide a prospective benefit in the realization of IR imagers with suppressed interband tunneling and Auger recombination processes, as well as high quantum efficiency and responsivity. With scaling of single pixel dimensions, the performance of focal plane arrays is strongly dependent on surface effects due to the large pixels’ surface/volume ratio. This article discusses the cause of surface leakage currents and various approaches of their reduction including dielectric passivation, passivation with organic materials (polyimide or various photoresists), passivation by overgrowth of wider bandgap material, and chalcogenide passivation. Performance of SLS detectors passivated by different techniques and operating in various regions of infrared spectrum has been compared.
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radiation tolerance characterization of dual band inas gasb type ii strain Layer Superlattice pbp detectors using 63 mev protons
Applied Physics Letters, 2012Co-Authors: Vincent M. Cowan, Elena Plis, Christian P. Morath, S Myers, John E Hubbs, Sanjay KrishnaAbstract:The radiation tolerance characterization of dual band InAs/GaSb type-II strain-Layer Superlattice pBp detectors of varying size using 63 MeV proton irradiation is presented. The detectors' mid-wave infrared performance degraded with increasing proton fluence ΦP up to 3.75 × 1012 cm−2 or, equivalently, a total ionizing dose = 500 kRad (Si). At this ΦP, an ∼31% drop in quantum efficiency η, ∼2 order increase in dark current density JD, and consequently, >1 order drop in calculated detectivity D* were observed. Proton damage factors were determined for η and D*. Arrhenius-analysis of temperature-dependent JD measurements reflected significant changes in the activation energies following irradiation.
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performance improvement of long wave infrared inas gasb strained Layer Superlattice detectors through sulfur based passivation
Infrared Physics & Technology, 2012Co-Authors: Elena Plis, M N Kutty, S Myers, A Rathi, E H Aifer, I Vurgaftman, Sanjay KrishnaAbstract:Abstract We report on effective sulfur-based passivation treatments of type-II InAs/GaSb strained Layer Superlattice detectors (100% cut-off wavelength is 9.8 μm at 77 K). The electrical behavior of detectors passivated by electrochemical sulfur deposition (ECP) and thioacetamide (TAM) was evaluated for devices of various sizes. ECP passivated detectors with a perimeter-to-area ratio of 1600 cm −1 exhibited superior performance with surface resistivity in excess of 10 4 Ω cm, dark current density of 2.7 × 10 −3 A/cm 2 , and specific detectivity improved by a factor of 5 compared to unpassivated devices ( V Bias = − 0.1 V, 77 K).
L R Dawson - One of the best experts on this subject based on the ideXlab platform.
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high operating temperature interband cascade midwave infrared detector based on type ii inas gasb strained Layer Superlattice
Applied Physics Letters, 2012Co-Authors: N Gautam, Ajit V. Barve, S Myers, B Klein, E P G Smith, David R Rhiger, L R DawsonAbstract:We report on an interband cascade mid-wave infrared (MWIR) detector based on type-II InAs/GaSb/AlSb strained Layer Superlattices (T2SL). The reported device has a seven-stage cascade region, each segment containing a MWIR absorber region, a graded T2SL transport region, and an interband tunneling region. Above room temperature spectral response was observed, with a cutoff wavelength of 7 μm at 420 K. Detailed radiometric measurements yielded a Johnson noise limited detectivity of 3.0 × 1011 cmHz1/2W−1 (8.9 × 108 cmHz1/2W−1) and a dark current density of 3.6 × 10−7 A/cm−2 (7.3 × 10−3 A/cm−2) near zero bias with a 100% cutoff wavelength of 5.2 μm and 6.2 μm at 77 K (295 K), respectively, with an estimated 36.2% QE.
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passivation of long wave infrared inas gasb strained Layer Superlattice detectors
Infrared Physics & Technology, 2011Co-Authors: Elena Plis, M N Kutty, N Gautam, S Myers, L R Dawson, H S Kim, Sanjay KrishnaAbstract:Abstract We have investigated various passivation techniques for type-II InAs/GaSb strained Layer Superlattice (SLS) detectors with p-i-n and PbIbN designs with a 100%-cut-off wavelength of ∼12 μm at 77 K. The passivation schemes include dielectric deposition (silicon nitride (SiN x ), silicon dioxide (SiO 2 ), photoresist (SU-8)), chalcogenide treatments (zinc sulfide (ZnS), ammonium sulfide [(NH 4 ) 2 S]), and electrochemical sulphur deposition. [(NH 4 ) 2 S] passivation and electrochemical sulphur passivation (ECP) showed the better performances, improving the dark current density by factors of 200 and 25 (p-i-n detector) and ∼3 and 54 (PbIbN detector), respectively ( T = 77 K, −0.1 V of applied bias). The specific detectivity D * was improved by a factor of 2 and by an order of magnitude for (NH 4 ) 2 S and ECP passivated PbIbN detectors, respectively.
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reduction of surface leakage current in inas gasb strained Layer long wavelength Superlattice detectors using su 8 passivation
Applied Physics Letters, 2010Co-Authors: Elena Plis, Y D Sharma, N Gautam, S Myers, L R Dawson, Sanjay KrishnaAbstract:We report on SU-8 passivation for reducing surface leakage current in type-II InAs/GaSb strained Layer Superlattice detectors (λ100% cut-off∼12 μm). The electrical behavior of SU-8 passivated and unpassivated devices was compared for devices with variable mesa sizes. Dark current was reduced by more than one order of magnitude for the small area (50 μm×50 μm) passivated diode at 77 K. The surface resistivity, the responsivity and specific detectivity were measured for SU-8 passivated devices and are equal to 204 Ω cm, 0.58 A/W and 3.49×109 Jones, respectively (77 K).
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performance improvement of longwave infrared photodetector based on type ii inas gasb Superlattices using unipolar current blocking Layers
Applied Physics Letters, 2010Co-Authors: N Gautam, Elena Plis, M N Kutty, L R Dawson, Sanjay KrishnaAbstract:We report here a heterojunction band gap engineered type-II InAs/GaSb strained Layer Superlattice photodiode for longwave infrared detection. The reported PbIbN architecture shows improved performance over conventional PIN design due to unipolar current blocking Layers. At 77 K and Vb=−0.25 V, responsivity of 1.8 A/W, dark current density of 1.2 mA/cm2, single pass quantum efficiency of 23%, and shot noise limited detectivity (D∗) of 8.7×1010 cm Hz1/2 W−1 (λc=10.8 μm) were measured. The device demonstrated background limited performance at 100 K under 300 K for 2π field of view.
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performance improvement of inas gasb strained Layer Superlattice detectors by reducing surface leakage currents with su 8 passivation
Applied Physics Letters, 2010Co-Authors: Elena Plis, Y D Sharma, N Gautam, S Myers, L R Dawson, A Khoshakhlagh, Sanjay KrishnaAbstract:We report on SU-8 passivation for performance improvement of type-II InAs/GaSb strained Layer Superlattice detectors (λcut-off∼4.6 μm). Optical and electrical behavior of SU-8 passivated and unpassivated devices was compared. The dark current density was improved by four orders of magnitude for passivated single diodes at 77 K. The zero bias responsivity and detectivity at 77 K was equal to 0.9 A/W and 3.5×1012 Jones for SU-8 passivated single pixel diodes. FPA size diodes (24×24 μm2) were also fabricated and they showed responsivity and detectivity of 1.3 A/W and 3.5×1012 Jones, respectively at 77 K.
Siddhartha Ghosh - One of the best experts on this subject based on the ideXlab platform.
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electrical characterization of different passivation treatments for long wave infrared inas gasb strained Layer Superlattice photodiodes
Journal of Electronic Materials, 2009Co-Authors: Koushik Banerjee, Elena Plis, Shubhrangshu Mallick, Siddhartha Ghosh, Sanjay KrishnaAbstract:Silicon dioxide (SiO2), silicon nitride (SixNy), and zinc sulfide (ZnS) with ammonium sulfide [(NH4)2S] as a prepassivation surface treatment were compared as passivants for InAs/GaSb strained Layer Superlattice detectors with a 0% cutoff wavelength of ∼10 μm. SiO2 did not show significant improvement and the zero-bias resistance-area product (R0A) was 0.72 Ω-cm2 at 77 K. SixNy passivation showed a nominal improvement with an R0A value of 4.1 Ω-cm2 at 77 K. ZnS with (NH4)2S treatment outperformed others significantly, improving the R0A value to 492 Ω-cm2 at 77 K. Variable-area diode measurements indicated a bulk-limited R0A value of 722 Ω-cm2. ZnS-passivated diodes exhibited maximum surface resistivity with a value of 2500 Ω-cm.
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midwave infrared inas gasb strained Layer Superlattice hole avalanche photodiode
Applied Physics Letters, 2009Co-Authors: Koushik Banerjee, Elena Plis, Sanjay Krishna, Shubhrangshu Mallick, Siddhartha Ghosh, Christoph H GreinAbstract:Midwavelength infrared InAs–GaSb strained Layer Superlattice n+-n−-p avalanche photodiodes, specifically designed to have hole dominated avalanching, with a zero percent cutoff wavelength of ∼6.3 μm are fabricated and characterized. Maximum multiplication gain of 105 is measured at −3.6 V at 77 K. Measured excess noise factors are significantly improved compared to unity hole to electron ionization ratio and corresponds to a theoretical value between 40 and 50 when compared with the McIntyre model. Exponential nature of the gain as a function of reverse bias along with low excess noise factors confirms single carrier hole dominated impact ionization.
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lateral diffusion of minority carriers in nbn based type ii inas gasb strained Layer Superlattice detectors
Applied Physics Letters, 2008Co-Authors: Elena Plis, Sanjay Krishna, Koushik Banerjee, G Bishop, H S Kim, Siddhartha GhoshAbstract:We report on the investigation of lateral diffusion of minority carriers in nBn based InAs/GaSb strained Layer Superlattice photodetectors. Values of diffusion length of minority carriers were extracted from temperature dependent I-V measurements. The behavior of diffusion length as a function of applied bias, temperature, and composition of the barrier Layer and the values ranging by two orders of magnitude from 77 to 250 K at the same value of applied bias were investigated. The obtained results suggest that at this point the lateral diffusion current could be the limiting factor of the MWIR nBn detector performance at low (<150 K) temperatures.
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ultralow noise midwave infrared inas gasb strain Layer Superlattice avalanche photodiode
Applied Physics Letters, 2007Co-Authors: Shubhrangshu Mallick, Elena Plis, J B Rodriguez, Sanjay Krishna, Koushik Banerjee, Siddhartha Ghosh, Christoph H GreinAbstract:Eye-safe midwavelength infrared InAs–GaSb strain Layer Superlattice p+-n−-n homojunction avalanche photodiodes (APDs) grown by solid source molecular beam epitaxy were fabricated and characterized. Maximum multiplication gain of 1800 was measured at −20V at 77K. Excess noise factors between 0.8 and 1.2 were measured up to gain of 300. Gain of 200 was measured at 120K. Exponential nature of the gain as a function of reverse bias along with low excess noise factor at higher gain confirms single carrier electron-only impact ionization in the avalanche regime. Decrease in the multiplication gain at higher temperatures correlates with standard APD characteristics.
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midwavelength infrared avalanche photodiode using inas gasb strain Layer Superlattice
IEEE Photonics Technology Letters, 2007Co-Authors: Shubhrangshu Mallick, J B Rodriguez, Koushik Banerjee, Siddhartha Ghosh, Sanjay KrishnaAbstract:InAs-GaSb strain Layer Superlattice p+-n--n avalanche photodiodes (APDs) are fabricated using a newly introduced electron-beam aided zinc sulfide deposition. Temperature-dependent measurements were performed on 300 times 300 mum2 mesa etched APDs. The effect of passivation was also studied on the diode characteristics and APD performances. Temperature-dependent gain strongly correlates with avalanche mechanism.
S Myers - One of the best experts on this subject based on the ideXlab platform.
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impact of temperature and gamma radiation on electron diffusion length and mobility in p type inas gasb Superlattices
Journal of Applied Physics, 2018Co-Authors: Jonathan Lee, Sanjay Krishna, Leonid Chernyak, Chris J Fredricksen, Elena Flitsiyan, Robert E Peale, Zahra Taghipour, Lilian K Casias, Alireza Kazemi, S MyersAbstract:The minority carrier diffusion length was directly measured by the variable-temperature Electron Beam-Induced Current technique in InAs/GaSb type-II strain-Layer-Superlattice infrared-detector structures. The Molecular Beam Epitaxy-grown midwave infrared Superlattices comprised 10 monoLayers of InAs and 10 monoLayers of GaSb to give a total absorber thickness of 4 μm. The diffusion length of minority electrons in the p-type absorber region of the p-type/barrier/n-type structure was found to increase from 1.08 to 2.24 μm with a thermal activation energy of 13.1 meV for temperatures ranging from 77 to 273 K. These lengths significantly exceed the individual 10-monoLayer thicknesses of the InAs and GaSb, possibly indicating a low impact of interface scattering on the minority carrier diffusion length. The corresponding minority electron mobility varied from 48 to 65 cm2/V s. An absorbed gamma irradiation dose of 500 Gy halved the minority carrier diffusion length and increased the thermal activation energy to 18.6 meV, due to creation of radiation-induced defect recombination centers.
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comparison of mwir unipolar barrier structures based on strained Layer Superlattices conference presentation
Proceedings of SPIE, 2016Co-Authors: David A. Ramirez, Christian P. Morath, S Myers, Elizabeth H Steenbergen, Yuliya Kuznetsova, Sen Mathews, T Schulersandy, Vicent M Cowan, Sanjay KrishnaAbstract:In this work, we compare the performance of three MWIR unipolar barrier structures based on the InAs/GaSb Type-2 strained Layer Superlattice material system. We have designed, fabricated, and characterized pBiBn, pBn, and pBp detector structures. All the structures have been designed so that the cut off wavelength is around 5 microns at 100 K. We fabricated single-pixel devices and characterize their radiometric performance. In addition, we have characterized the degradation of the performance of the devices after exposing the devices to 63 MeV proton radiation to total ionizing dose of 100 kRad (Si). In this report, we compare the performance of the different structures with the objective of determining the advantages and disadvantages of the different designs. This work was supported by the Small Business Innovation Research (SBIR) program under the contract FA9453-14-C-0032, sponsored by the Air Force Research Laboratory (AFRL).
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dual color longwave inas gasb type ii strained Layer Superlattice detectors
Infrared Physics & Technology, 2015Co-Authors: Elena Plis, David A. Ramirez, S Myers, E P G Smith, David R Rhiger, Chihyu Chen, J D Phillips, Sanjay KrishnaAbstract:Abstract We report on the design, growth, fabrication and characterization of dual-band (long-/long-wave infrared) type-II InAs/GaSb strained Layer Superlattice (T2SL) detectors with pBp architecture. Under operating the bias of −200 mV and +100 mV, quantum efficiencies of 37% (∼11 μm band) and 25% (∼9 μm band) were realized, respectively. To reduce the dark current in a dual-band T2SL detector, the effect of a “restoration” chemical etch treatment and ZnTe passivation on device performance were investigated.
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radiation tolerance characterization of dual band inas gasb type ii strain Layer Superlattice pbp detectors using 63 mev protons
Applied Physics Letters, 2012Co-Authors: Vincent M. Cowan, Elena Plis, Christian P. Morath, S Myers, John E Hubbs, Sanjay KrishnaAbstract:The radiation tolerance characterization of dual band InAs/GaSb type-II strain-Layer Superlattice pBp detectors of varying size using 63 MeV proton irradiation is presented. The detectors' mid-wave infrared performance degraded with increasing proton fluence ΦP up to 3.75 × 1012 cm−2 or, equivalently, a total ionizing dose = 500 kRad (Si). At this ΦP, an ∼31% drop in quantum efficiency η, ∼2 order increase in dark current density JD, and consequently, >1 order drop in calculated detectivity D* were observed. Proton damage factors were determined for η and D*. Arrhenius-analysis of temperature-dependent JD measurements reflected significant changes in the activation energies following irradiation.
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high operating temperature interband cascade midwave infrared detector based on type ii inas gasb strained Layer Superlattice
Applied Physics Letters, 2012Co-Authors: N Gautam, Ajit V. Barve, S Myers, B Klein, E P G Smith, David R Rhiger, L R DawsonAbstract:We report on an interband cascade mid-wave infrared (MWIR) detector based on type-II InAs/GaSb/AlSb strained Layer Superlattices (T2SL). The reported device has a seven-stage cascade region, each segment containing a MWIR absorber region, a graded T2SL transport region, and an interband tunneling region. Above room temperature spectral response was observed, with a cutoff wavelength of 7 μm at 420 K. Detailed radiometric measurements yielded a Johnson noise limited detectivity of 3.0 × 1011 cmHz1/2W−1 (8.9 × 108 cmHz1/2W−1) and a dark current density of 3.6 × 10−7 A/cm−2 (7.3 × 10−3 A/cm−2) near zero bias with a 100% cutoff wavelength of 5.2 μm and 6.2 μm at 77 K (295 K), respectively, with an estimated 36.2% QE.