Center for Quantum Devices - Journal Articles and Conference Proceedings

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1.	Low Noise Short Wavelength Infrared Avalanche Photodetector Using SB-Based Strained Layer Superlattice Arash Dehzangi, Jiakai Li, Manijeh Razeghi Photonics 2021, 8(5), 148; https://doi.org/10.3390/photonics8050148 Received: 8 March 2021 / Revised: 12 April 2021 / Accepted: 25 April 2021 / Published: 30 April 2021 We demonstrate low noise short wavelength infrared (SWIR) Sb-based type II superlattice (T2SL) avalanche photodiodes (APDs). The SWIR GaSb/(AlAsSb/GaSb) APD structure was designed based on impact ionization engineering and grown by molecular beam epitaxy on a GaSb substrate. At room temperature, the device exhibits a 50% cut-off wavelength of 1.74 µm. The device was revealed to have an electron-dominated avalanching mechanism with a gain value of 48 at room temperature. The electron and hole impact ionization coefficients were calculated and compared to give a better prospect of the performance of the device. Low excess noise, as characterized by a carrier ionization ratio of ~0.07, has been achieved. reprint
2.	Mid‑wavelength infrared avalanche photodetector with AlAsSb/GaSb superlattice Jiakai Li, Arash Dehzangi, Gail Brown, Manijeh Razeghi Scientifc Reports \| (2021) 11:7104 \| https://doi.org/10.1038/s41598-021-86566-8 In this work, a mid-wavelength infrared separate absorption and multiplication avalanche photodiode (SAM-APD) with 100% cut-of wavelength of ~ 5.0 µm at 200 K grown by molecular beam epitaxy was demonstrated. The InAsSb-based SAM-APD device was designed to have electron dominated avalanche mechanism via the band structure engineered multi-quantum well structure based on AlAsSb/GaSb H-structure superlattice and InAsSb material in the multiplication region. The device exhibits a maximum multiplication gain of 29 at 200 K under -14.7 bias voltage. The maximum multiplication gain value for the MWIR SAM-APD increases from 29 at 200 K to 121 at 150 K. The electron and hole impact ionization coefficients were derived and the large difference between their value was observed. The carrier ionization ratio for the MWIR SAM-APD device was calculated to be ~ 0.097 at 200 K. reprint
3.	Performance analysis of infrared heterojunction phototransistors based on Type-II superlattices Jiakai Li, Arash Dehzangi, Manijeh Razeghi Infrared Physics & Technology Volume 113, March 2021, 103641 In this study, a comprehensive analysis of the n-p-n infrared heterojunction phototransistors (HPTs)based on Type-II superlattices has been demonstrated. Different kinds of Type-II superlattices were carefully chosen for the emitter, base, and collector to improve the optical performance. The effects of different device parameters include emitter doping concentration, base doping concentration, base thickness and energy bandgap difference between emitter and base on the optical gain of the HPTs have been investigated. By scaling the base thickness to 20 nm, the HPT exhibits an optical gain of 345.3 at 1.6 μm at room temperature. For a 10 μm diameter HPT device, a −3 dB cut-off frequency of 5.1 GHz was achieved under 20 V at 150 K. reprint
4.	Band-structure-engineered high-gain LWIR photodetector based on a type-II superlattice Arash Dehzangi, Jiakai Li and Manijeh Razeghi Light: Science & Applications volume 10, Article number: 17 (2021) https://doi.org/10.1038/s41377-020-00453-x The LWIR and longer wavelength regions are of particular interest for new developments and new approaches to realizing long-wavelength infrared (LWIR) photodetectors with high detectivity and high responsivity. These photodetectors are highly desirable for applications such as infrared earth science and astronomy, remote sensing, optical communication, and thermal and medical imaging. Here, we report the design, growth, and characterization of a high-gain band-structure-engineered LWIR heterojunction phototransistor based on type-II superlattices. The 1/e cut-off wavelength of the device is 8.0 µm. At 77 K, unity optical gain occurs at a 90 mV applied bias with a dark current density of 3.2 × 10−7 A/cm2. The optical gain of the device at 77 K saturates at a value of 276 at an applied bias of 220 mV. This saturation corresponds to a responsivity of 1284 A/W and a specific detectivity of 2.34 × 1013 cm Hz1/2/W at a peak detection wavelength of ~6.8 µm. The type-II superlattice-based high-gain LWIR device shows the possibility of designing the high-performance gain-based LWIR photodetectors by implementing the band structure engineering approach. reprint
5.	Multi-band SWIR-MWIR-LWIR Type-II superlattice based infrared photodetector Manijeh Razeghi, Arash Dehzangi, Jiakai Li Results in Optics Volume 2, January 2021, 100054 https://doi.org/10.1016/j.rio.2021.100054 Type-II InAs/GaSb superlattices (T2SLs) has drawn a lot of attention since it was introduced in 1970, especially for infrared detection as a system of multi-interacting quantum wells. In recent years, T2SL material system has experienced incredible improvements in material quality, device structure designs and device fabrication process, which elevated the performances of T2SL-based photo-detectors to a comparable level to the state-of-the-art material systems for infrared detection such as Mercury Cadmium Telluride (MCT). As a pioneer in the field, center for quantum devices (CQD) has been involved in growth, design, characterization, and introduction of T2SL material system for infrared photodetection. In this review paper, we will present the latest development of bias-selectable multi-band infrared photodetectors at the CQD, based on InAs/GaSb/AlSb and InAs/InAs1-xSbx type-II superlattice. reprint
6.	Avalanche Photodetector Based on InAs/InSb Superlattice Arash Dehzangi, Jiakai Li, Lakshay Gautam and Manijeh Razeghi Quantum rep. 2020, 2(4), 591-599; https://doi.org/10.3390/quantum2040041 (registering DOI)-- December 4, 2020 This work demonstrates a mid-wavelength infrared InAs/InSb superlattice avalanche photodiode (APD). The superlattice APD structure was grown by molecular beam epitaxy on GaSb substrate. The device exhibits a 100 % cut-off wavelength of 4.6 µm at 150 K and 4.30 µm at 77 K. At 150 and 77 K, the device responsivity reaches peak values of 2.49 and 2.32 A/W at 3.75 µm under −1.0 V applied bias, respectively. The device reveals an electron dominated avalanching mechanism with a gain value of 6 at 150 K and 7.4 at 77 K which was observed under −6.5 V bias voltage. The gain value was measured at different temperatures and different diode sizes. The electron and hole impact ionization coefficients were calculated and compared to give a better prospect of the performance of the device. reprint
7.	Resonant cavity enhanced heterojunction phototransistors based on type-II superlattices Jiakai Li, Arash Dehzangi, Donghai Wu, Ryan McClintock, Manijeh Razeghi Infrared Physics & Technology Available online 27 October 2020, 103552 https://doi.org/10.1016/j.infrared.2020.103552-- October 27, 2020 Resonant cavity enhanced heterojunction phototransistor based on InAs/GaSb/AlSb type-II superlattice grown by molecular beam epitaxy has been demonstrated. The resonant wavelength was designed to be at near 1.9 μm wavelength range at room temperature. An eleven-pair lattice matched GaSb-AlAsSb quarter-wavelength Bragg reflector was used in the RCE-HPT to enhance the photoresponse. The device showed the wavelength selectivity and a cavity enhancement of the responsivity at 1.9 μm at room temperature. reprint
8.	Demonstration of Planar Type-II Superlattice-Based Photodetectors Using Silicon Ion-Implantation Arash Dehzangi, Donghai Wu, Ryan McClintock, Jiakai Li, Alexander Jaud and Manijeh Razeghi Photonics 2020, 7(3), 68; https://doi.org/10.3390/photonics7030068-- September 3, 2020 In this letter, we report the demonstration of a pBn planar mid-wavelength infrared photodetectors based on type-II InAs/InAs1−xSbx superlattices, using silicon ion-implantation to isolate the devices. At 77 K the photodetectors exhibited peak responsivity of 0.76 A/W at 3.8 µm, corresponding to a quantum efficiency, without anti-reflection coating, of 21.5% under an applied bias of +40 mV with a 100% cut-off wavelength of 4.6 µm. With a dark current density of 5.21 × 10−6 A/cm2, under +40 mV applied bias and at 77 K, the photodetector exhibited a specific detectivity of 4.95 × 1011 cm·Hz1/2/W. reprint
9.	High Performance InAs/InAsSb Type-II Superlattice Mid-Wavelength Infrared Photodetectors with Double Barrier Donghai Wu, Jiakai Li, Arash Dehzangi, Manijeh Razeghi Infrared Physics &Technology 103439-- July 18, 2020 By introducing a double barrier design, a high performance InAs/InAsSb type-II superlattice mid-wavelength infrared photodetector has been demonstrated. The photodetector exhibits a cut-off wavelength of ~4.50 µm at 150 K. At 150 K and −120 mV applied bias, the photodetector exhibits a dark current density of 1.21 × 10−5 A/cm2, a quantum efficiency of 45% at peak responsivity (~3.95 µm), and a specific detectivity of 6.9 × 1011 cm·Hz1/2/W. The photodetector shows background-limited operating temperature up to 160 K. reprint
10.	Planar nBn type-II superlattice mid-wavelength infrared photodetectors using zinc ion-implantation Arash Dehzangi, Donghai Wu, Ryan McClintock, Jiakai Li, and Manijeh Razeghi Appl. Phys. Lett. 116, 221103 https://doi.org/10.1063/5.0010273-- June 2, 2020 In this Letter, we report the demonstration of zinc ion-implantation to realize planar mid-wavelength infrared photodetectors based on type-II InAs/InAs1−xSbx superlattices. At 77 K, the photodetectors exhibit a peak responsivity of 0.68 A/W at 3.35 μm, corresponding to a quantum efficiency of 23.5% under Vb = −80 mV, without anti-reflection coating; these photodetectors have a 100% cutoff wavelength of 4.28 μm. With an R0 × A value of 1.53 × 104 Ω cm2 and a dark current density of 1.23 × 10−6 A/cm2 under an applied bias of −80 mV at 77 K, the photodetectors exhibit a specific detectivity of 9.12 × 1011 cm·Hz1/2/W. reprint
11.	Type-II superlattice-based heterojunction phototransistors for high speed applications Jiakai Li, Arash Dehzangi, Donghai Wu, Ryan McClintock, Manijeh Razeghi Infrared Physics and Technology 108, 1033502-- May 2, 2020 In this study, high speed performance of heterojunction phototransistors (HPTs) based on InAs/GaSb/AlSb type-II superlattice with 30 nm base thickness and 50% cut-off wavelength of 2.0 μm at room temperature are demonstrated. We studied the relationship between -3 dB cut-off frequency of these HPT versus mesa size, applied bias, and collector layer thickness. For 8 μm diameter circular mesas HPT devices with a 0.5 μm collector layer, under 20 V applied bias voltage, we achieved a -3 dB cut-off frequency of 2.8 GHz. reprint
12.	High performance Zn-diffused planar mid-wavelength infrared type-II InAs/InAs_1-xSb_x superlattice photodetector by MOCVD Donghai Wu, Arash Dehzangi, Jiakai Li, and Manijeh Razeghi Appl. Phys. Lett. 116, 161108-- April 21, 2020 We report a Zn-diffused planar mid-wavelength infrared photodetector based on type-II InAs/InAs_1-xSb_x superlattices. Both the superlattice growth and Zn diffusion were performed in a metal-organic chemical vapor deposition system. At 77K, the photodetector exhibits a peak responsivity of 0.70A/W at 3.65λ, corresponding to a quantum efﬁciency of 24% at zero bias without anti-reﬂection coating, with a 50% cutoff wavelength of 4.28λ. With an R₀A value of 3.2x10⁵ Ω·cm² and a dark current density of 9.6x10^-8 A/cm² bias of -20mV at 77K, the photodetector exhibits a speciﬁc detectivity of 2.9x10¹²cm·Hz^½/W. At 150K, the photodetector exhibits a dark current density of 9.1x10^-6 A/cm² and a quantum efﬁciency of 25%, resulting in a detectivity of 3.4x10¹¹cm·Hz/W. reprint
13.	Mid-wavelength infrared high operating temperature pBn photodetectors based on type-II InAs/InAsSb superlattice Donghai Wu, Jiakai Li, Arash Dehzangi, and Manijeh Razeghi AIP Advances 10, 025018-- February 11, 2020 A high operating temperature mid-wavelength infrared pBn photodetector based on the type-II InAs/InAsSb superlattice on a GaSb substrate has been demonstrated. At 150 K, the photodetector exhibits a peak responsivity of 1.48 A/W, corresponding to a quantum efficiency of 47% at −50 mV applied bias under front-side illumination, with a 50% cutoff wavelength of 4.4 μm. With an R×A of 12,783 Ω·cm² and a dark current density of 1.16×10⁻⁵A/cm² under −50 mV applied bias, the photodetector exhibits a specific detectivity of 7.1×10¹¹ cm·Hz^½/W. At 300 K, the photodetector exhibits a dark current density of 0.44 A/cm²and a quantum efficiency of 39%, resultingin a specific detectivity of 2.5×10⁹ cm·Hz^½/W. reprint
14.	High-speed short wavelength infrared heterojunction phototransistors based on type II superlattices Jiakai Li; Arash Dehzangi; Donghai Wu; Manijeh Razeghi Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128813-- January 31, 2020 A two terminal short wavelength infrared heterojunction phototransistors based on type-II InAs/AlSb/GaSb on GaSb substrate are designed fabricated and presented. With the base thickness of 40 nm, the device exhibited 100% cut-off wavelengths of ~2.3 μm at 300K. The saturated peak responsivity value is of 325.5 A/W at 300K, under front-side illumination without any anti-reflection coating. A saturated optical gain at 300K was 215 a saturated dark current shot noise limited specific detectivity of 4.9×10¹¹ cm·Hz^½/W at 300 K was measured. Similar heterojunction phototransistor structure was grown and fabricated with different method of processing for high speed testing. For 80 μm diameter circular diode size under 20 V applied reverse bias, a −3 dB cut-off frequency of 1.0 GHz was achieved, which showed the potential of type-II superlattice based heterojunction phototransistors to be used for high speed detection. reprint
15.	High speed type-II superlattice based photodetectors transferred on sapphire Arash Dehzangi, Ryan McClintock, Donghai Wu, Jiakai Li, Stephen Johnson, Emily Dial and Manijeh Razeghi Applied Physics Express, Volume 12, Number 11-- October 3, 2019 We report the substrate transfer of InAs/GaSb/AlSb based type-II superlattice (T2SL) e-SWIR photodetector from native GaSb substrates to low loss sapphire substrate in order to enhance the frequency response of the device. We have demonstrated the damage-free transfer of T2SL-based thin-films to sapphire substrate using top–down processing and a chemical epilayer release technique. After transfer the −3 dB cut-off frequency increased from 6.4 GHz to 17.2 GHz, for 8 μm diameter circular mesas under -15 V applied bias. We also investigated the cut-off frequency verses applied bias and lateral scaling to assess the limitations for even higher frequency performance. Direct Link reprint
16.	MOCVD grown β-Ga₂O₃ metal-oxide-semiconductor field effect transistors on sapphire Ji-Hyeon Park , Ryan McClintock, Alexandre Jaud, Arash Dehzangi , Manijeh Razeghi Applied Physics Express 12, 095503-- August 28, 2019 We fabricated β-Ga₂O₃:Si metal-oxide field-effect transistors (MOSFETs) on c-plane sapphire substrates which typically showed maximum drain current of 100 mA·mm⁻¹. β-Ga₂O₃:Si thin films were realized on c-plane sapphire substrates through a combination of metalorganic chemical vapor deposition and post-annealing. The MOSFET device presented excellent on/off drain current ratio of ∼10¹¹ with very low gate leakage current, sharp pinch off behavior, and a breakdown voltage of 400 V at VG = −40 V. The growth and fabrication of β-Ga₂O₃:Si MOSFETs on c-plane sapphire is valuable to its demonstration of the great potential for future high-power electronic devices. reprint
17.	Demonstration of mid-wavelength infrared nBn photodetectors based on type-II InAs/InAs_1-xSb_x superlattice grown by metal-organic chemical vapor deposition Donghai Wu, Arash Dehzangi, and Manijeh Razeghi Appl. Phys. Lett. 115, 061102-- August 6, 2019 We report design, growth, and characterization of midwavelength infrared nBn photodetectors based on a type-II InAs/InAs_1-xSb_x superlattice on a GaSb substrate grown by metal-organic chemical vapor deposition. An InAs/AlAs_1-ySb_y/InAs/InAs_1-xSb_x superlattice design was used as the large bandgap electron barrier in the photodetectors. At 150 K, the photodetector exhibits a peak responsivity of 1.23 A/W, corresponding to a quantum efficiency of 41% at an applied bias voltage of −100 mV under front-side illumination, with a 50% cut-off wavelength of 4.6 μm. With an R × A of 356 Ω·cm² and a dark current density of 1.6 × 10⁻⁴ A/cm² under an applied bias of −100 mV at 150 K, the photodetector exhibits a specific detectivity of 1.4 × 10¹¹ cm·Hz^1/2/W. reprint
18.	Investigation of surface leakage reduction for small pitch shortwave infrared photodetectors Arash Dehzangi, Quentin Durlin, Donghai Wu, Ryan McClintock, Manijeh Razeghi Semiconductor Science and Technology, 34(6), 06LT01-- May 25, 2019 Different passivation techniques are investigated for reducing leakage current in small pixel (down to 9 μm) heterostructure photodetectors designed for the short-wavelength infrared range. Process evaluation test chips were fabricated using the same process as for focal plane arrays. Arrays of small photodetectors were electrically characterized under dark conditions from 150 K to room temperature. In order to evaluate the leakage current, we studied the relation between the inverse of dynamic resistance at −20 mV and zero bias and perimeter over area P/A ratio as the pixel size is scaled down. At 150 K, leakage current arising from the perimeter dominates while bulk leakage dominates at room temperature. We find that in shortwave devices directly underfilling hybridized devices with a thermoset epoxy resin without first doing any additional passivation/protection after etching gives the lowest leakage with a surface resistance of 4.2 × 10⁹ and 8.9 × 10³ Ω· cm⁻¹ at 150 and 300 K, for −20 mV of bias voltage, respectively. reprint
19.	Extended short wavelength infrared heterojunction phototransistors based on type II superlattices Arash Dehzangi , Ryan McClintock, Donghai Wu , Abbas Haddadi, Romain Chevallier , and Manijeh Razeghi Applied Physics Letters 114, 191109-- May 17, 2019 A two terminal extended short wavelength infrared heterojunction phototransistor based on type-II InAs/AlSb/GaSb on a GaSb substrate is designed, fabricated, and investigated. With the base thickness of 40 nm, the device exhibited a 100% cut-off wavelength of 2.3 λ at 300 K. The saturated peak responsivity value is 320.5 A/W at 300 K, under front-side illumination without any antireflection coating. A saturated optical gain of 245 at 300K was measured. At the same temperature, the device exhibited a collector dark current density (at unity optical gain) and a DC current gain of 7.8 X 10³ A/cm² and 1100, respectively. The device exhibited a saturated dark current shot noise limited specific detectivity of 4.9 X 10¹¹ cm·Hz^½/W at 300 K which remains constant over a broad range of wavelengths and applied biases. reprint
20.	Antimonite-based gap-engineered type-II superlattice materials grown by MBE and MOCVD for the third generation of infrared imagers Manijeh Razeghi, Arash Dehzangi, Donghai Wu, Ryan McClintock, Yiyun Zhang, Quentin Durlin, Jiakai Li, Fanfei Meng Proc. SPIE Defense + Commercial Sensing,Infrared Technology and Applications XLV, 110020G -- May 7, 2019 Third generation of infrared imagers demand performances for higher detectivity, higher operating temperature, higher resolution, and multi-color detection all accomplished with better yield and lower manufacturing costs. Antimonidebased gap-engineered Type-II superlattices (T2SLs) material system is considered as a potential alternative for MercuryCadmium-Telluride (HgCdTe) technology in all different infrared detection regimes from short to very long wavelengths for the third generation of infrared imagers. This is due to the incredible growth in the understanding of its material properties and improvement of device processing which leads to design and fabrication of better devices. We will present the most recent research results on Antimonide-based gap-engineered Type-II superlattices, such as highperformance dual-band SWIR/MWIR photo-detectors and focal plane arrays for different infrared regimes, toward the third generation of infrared imaging systems at the Center for Zuantum Devices. Comparing metal-organic chemical vapor deposition (MOCVD), vs molecular beam epitaxy (MBE). reprint
21.	Type–II superlattices base visible/extended short–wavelength infrared photodetectors with a bandstructure–engineered photo–generated carrier extractor Arash Dehzangi, Ryan McClintock, Abbas Haddadi, Donghai Wu, Romain Chevallier, Manijeh Razeghi Scientific Reports volume 9, Article number: 5003 -- March 21, 2019 Visible/extended short–wavelength infrared photodetectors with a bandstructure–engineered photo–generated carrier extractor based on type–II InAs/AlSb/GaSb superlattices have been demonstrated. The photodetectors are designed to have a 100% cut-off wavelength of ~2.4 μm at 300K, with sensitivity down to visible wavelengths. The photodetectors exhibit room–temperature (300K) peak responsivity of 0.6 A/W at ~1.7 μm, corresponding to a quantum efficiency of 43% at zero bias under front–side illumination, without any anti–reflection coating where the visible cut−on wavelength of the devices is <0.5 µm. With a dark current density of 5.3 × 10⁻⁴ A/cm² under −20 mV applied bias at 300K, the photodetectors exhibit a specific detectivity of 4.72 × 10¹⁰ cm·Hz^½W^-1. At 150K, the photodetectors exhibit a dark current density of 1.8 × 10⁻¹⁰ A/cm² and a quantum efficiency of 40%, resulting in a detectivity of 5.56 × 10¹³ cm·Hz^½/W reprint
22.	Fabrication of 12 µm pixel-pitch 1280 × 1024 extended short wavelength infrared focal plane array using heterojunction type-II superlattice-based photodetector Arash Dehzangi , Abbas Haddadi, Romain Chevallier, Yiyun Zhang and Manijeh Razegh Semicond. Sci. Technol. 34, 03LT01-- February 4, 2019 We present an initial demonstration of a 1280 × 1024 extended short-wavelength infrared focal plane array (FPA) imager with 12μm pixel-pitch based on type–II InAs/AlSb/GaSb superlattice heterojunction photodetectors, with a novel bandstructure-engineered photo-generated carrier extractor as the window layer in the hetero structure to efﬁciently extract the photo-generated carriers. This heterostructure with a larger bandgap top window/contact layer leads to the device having lower dark current density compared to conventional pn junction devices. The large format FPA was fabricated with 12 μm pixel-pitch using a developed fabrication process. Test pixels fabricated separately exhibit 100% cut–off wavelengths of ∼2.22, ∼2.34μm, and ∼2.45μm at 150, 200K, and 300K. The test devices achieve saturated quantum efﬁciency values under zero bias of 54.3% and 68.4% at 150 and 300K, under back-side illumination and without any anti-reﬂection coating. At 150K, these photodetectors exhibit dark current density of 1.63 × 10⁻⁷ A·cm⁻² under −20mV applied bias providing a speciﬁc detectivity of 1.01 × 10¹¹ cm ·Hz^½/W at 1.9μm. reprint
23.	High quantum efficiency mid-wavelength infrared type-II InAs/InAs_1-xSb_x superlattice photodiodes grown by metal-organic chemical vapor deposition Donghai Wu , Quentin Durlin, Arash Dehzangi , Yiyun Zhang , and Manijeh Razeghi Appl. Phys. Lett. 114, 011104-- January 8, 2019 We report the growth and characterization of mid-wavelength infrared type-II InAs/InAs_1-xSb_x superlattice photodiodes on GaSb substrates grown by metal-organic chemical vapor deposition. At 150 K, the 50% cut-off wavelength is 5.0 um, the dark current density is 3.3x10⁻⁴ A/cm² under −20mV bias, and the peak responsivity is 1.76A/W corresponding to a quantum efficiency of 55% without anti-reflection coating. A specific detectivity of 1.2x10¹¹cmHz^1/2/W is achieved at 4.0 um under −20mV bias at 150 K. reprint
24.	High Frequency Extended Short-Wavelength Infrared Heterojunction Photodetectors Based on InAs/GaSb/AlSb Type-II Superlattices Romain Chevallier, Abbas Haddadi, Ryan McClintock, Arash Dehzangi , Victor Lopez-Dominguez, Pedram Khalili Amiri, Manijeh Razeghi IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 54, NO. 6-- December 1, 2018 InAs/GaSb/AlSb type-II superlattice-based photodetectors, with 50% cut-off wavelength of 2.1 µm and a −3 dB cut-off frequency of 4.8 GHz, are demonstrated, for 10 µm diameter circular mesas under 15 V applied reverse bias. A study of the cut-off frequency with applied bias and mesa size was performed to evaluate some of the limiting factors of photodetectors high frequency performance. reprint
25.	Suppressing Spectral Crosstalk in Dual-Band LongWavelength Infrared Photodetectors With Monolithically Integrated Air-Gapped Distributed Bragg Reﬂectors Yiyun Zhang, Abbas Haddadi, Arash Dehzangi , Romain Chevallier, Manijeh Razeghi IEEE Journal of Quantum Electronics Volume: 55, Issue:1-- November 22, 2018 Antimonide-based type-II superlattices (T2SLs) have made possible the development of high-performance infrared cameras for use in a wide variety of thermal imaging applications, many of which could beneﬁt from dual-band imaging. The performance of this material system has not reached its limits. One of the key issues in dual-band infrared photodetection is spectral crosstalk. In this paper, air-gapped distributed Bragg reﬂectors (DBRs) have been monolithically integrated between the two channels in long-/very long-wavelength dualband InAs/InAs_1−xSb_x/AlAs_1−xSb_x-based T2SLs photodetectors to suppress the spectral crosstalk. This air-gapped DBR has achieved a signiﬁcant spectral suppression in the 4.5–7.5-µm photonic stopband while transmitting the optical wavelengths beyond 7.5 µm, which is conﬁrmed by theoretical calculations, numerical simulation, and experimental results. reprint

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