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1.  
Room temperature quantum cascade lasers with 22% wall plug efficiency in continuous-wave operation
Room temperature quantum cascade lasers with 22% wall plug efficiency in continuous-wave operation
F. Wang, S. Slivken, D. H. Wu, and M. Razeghi
Optics Express Vol. 28, Issue 12, pp. 17532-17538 (2020) •https://doi.org/10.1364/OE.394916-- June 8, 2020
We report the demonstration of quantum cascade lasers (QCLs) with improved efficiency emitting at a wavelength of 4.9µm in pulsed and continuous-wave(CW)operation. Based on an established design and guided by simulation, the number of QCL-emitting stages is increased in order to realize a 29.3% wall plug efficiency (WPE) in pulsed operation at room temperature. With proper fabrication and packaging, a 5-mm-long, 8-µm-wide QCL with a buried ridge waveguide is capable of 22% CW WPE and 5.6 W CW output power at room temperature. This corresponds to an extremely high optical density at the output facet of ∼35 MW/cm2, without any damage. reprint
 
2.  
Planar nBn type-II superlattice mid-wavelength infrared photodetectors using zinc ion-implantation
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 (2020); doi: 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 77K, 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=−80mV, without anti-reflection coating; these photodetectors have a 100% cutoff wavelength of 4.28 μm. With an R0 x A value of 1.53x104 Ω·cm² and a dark current density of 1.23x10−6 A/cm² under an applied bias of −80mV at 77K, the photodetectors exhibit a specific detectivity of 9.12x1011cm·Hz½/W. reprint
 
3.  
Continuous wave quantum cascade lasers with 5.6 W output power at room temperature and 41% wall-plug efficiency in cryogenic operation
Continuous wave quantum cascade lasers with 5.6 W output power at room temperature and 41% wall-plug efficiency in cryogenic operation
F. Wang, S. Slivken, D. H. Wu, Q. Y. Lu, and M. Razeghi
AIP Advances 10, 055120 (2020); https://doi.org/10.1063/5.0003318-- May 19, 2020
In this paper, we report a post-polishing technique to achieve nearly complete surface planarization for the buried ridge regrowth processing of quantum cascade lasers. The planarized device geometry improves the thermal conduction and reliability and, most importantly, enhances the power and efficiency in continuous wave operation. With this technique, we demonstrate a high continuous wave wall-plug efficiency of an InP-based quantum cascade laser reaching ∼41% with an output power of ∼12 W from a single facet operating at liquid nitrogen temperature. At room temperature, the continuous wave output power exceeds the previous record, reaching ∼5.6 W. reprint
 
4.  
High power continuous wave operation of single mode quantum cascade lasers up to 5 W spanning λ∼3.8-8.3 µm
High power continuous wave operation of single mode quantum cascade lasers up to 5 W spanning λ∼3.8-8.3 µm
Quanyong Lu, Steven Slivken, Donghai Wu, and Manijeh Razeghi
Optics Express Vol. 28, Issue 10, pp. 15181-15188 (2020)-- May 4, 2020
In this work, we report high power continuous wave room-temperature operation single mode quantum cascade lasers in the mid-infrared spectral range from 3.8 to 8.3 µm. Single mode robustness and dynamic range are enhanced by optimizing the distributed feedback grating coupling design and the facet coatings. High power single mode operation is secured by circumventing the over-coupling issue and spatial hole burning effect. Maximum single-facet continuous-wave output power of 5.1 W and wall plug efficiency of 16.6% is achieved at room temperature. Single mode operation with a side mode suppression ratio of 30 dB and single-lobed far field with negligible beam steering is observed. The significantly increased power for single mode emission will boost the QCL applications in long-range free-space communication and remote sensing of hazardous chemicals. reprint
 
5.  
Type-II superlattice-based heterojunction phototransistors for high speed applications
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 (2020) 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
 
6.  
Sb-based third generation at Center for Quantum Devices
Sb-based third generation at Center for Quantum Devices
Razeghi, Manijeh
SPIE Proceedings Volume 11407, Infrared Technology and Applications XLVI; 114070T (2020)-- April 23, 2020
Sb-based III-V semiconductors are a promising alternative to HgCdTe. They can be produced with a similar bandgap to HgCdTe, but take advantage of the strong bonding between group III and group V elements which leads to very stable materials, good radiation hardness, and high uniformity. In this paper, we will discuss the recent progress of our research and present the main contributions of the Center for Quantum Devices to the Sb-based 3th generation imagers. reprint
 
7.  
High performance Zn-diffused planar mid-wavelength infrared type-II InAs/InAs<sub>1-x</sub>Sb<sub>x</sub> superlattice photodetector by MOCVD
High performance Zn-diffused planar mid-wavelength infrared type-II InAs/InAs1-xSbx superlattice photodetector by MOCVD
Donghai Wu, Arash Dehzangi, Jiakai Li, and Manijeh Razeghi
Appl. Phys. Lett. 116, 161108 (2020)-- April 21, 2020
We report a Zn-diffused planar mid-wavelength infrared photodetector based on type-II InAs/InAs1-xSbx 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·Hz½/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
 
8.  
High power, high wall-plug efficiency, high reliability, continuous-wave operation quantum cascade lasers at Center for Quantum Devices
High power, high wall-plug efficiency, high reliability, continuous-wave operation quantum cascade lasers at Center for Quantum Devices
Razeghi, Manijeh
SPIE Proceedings Volume 11296, Optical, Opto-Atomic, and Entanglement-Enhanced Precision Metrology II; 112961C (25 February 2020) -- February 25, 2020
Since the demonstration of the first quantum cascade laser (QCL) in 1997, QCLs have undergone considerable developments in output power, wall plug efficiency (WPE), beam quality, wavelength coverage and tunability. Among them, many world-class breakthroughs were achieved at the Center for Quantum Device at Northwestern University. In this paper, we will discuss the recent progress of our research and present the main contributions of the Center for Quantum Devices to the QCL family on high power, high wall-plug efficiency (WPE), continuous-wave (CW) and room temperature operation lasers. reprint
 
9.  
Mid-wavelength infrared high operating temperature pBn photodetectors based on type-II InAs/InAsSb superlattice
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 (2020)-- 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·Hz½/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·Hz½/W. reprint
 
10.  
Solar-blind photodetectors based on Ga<sub>2</sub>O<sub>3</sub> and III-nitrides
Solar-blind photodetectors based on Ga2O3 and III-nitrides
Ryan McClintock; Alexandre Jaud; Lakshay Gautam; Manijeh Razeghi
Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128803 (31 January 2020)-- January 31, 2020
Recently, there has been a surge of interest in the wide bandgap semiconductors for solar blind photo detectors (SBPD). This work presents our recent progress in the growth/doping of AlGaN and Ga2O3 thin films for solar blind detection applications. Both of these thin films grown are grown by metal organic chemical vapor deposition (MOCVD) in the same Aixtron MOCVD system. Solar-blind metal-semiconductor-metal photodetectors were fabricated with Ga2O3. Spectral responsivity studies of the MSM photodetectors revealed a peak at 261 nm and a maximum EQE of 41.7% for a −2.5 V bias. We have also demonstrated AlGaN based solar-blind avalanche photodiodes with a gain in excess of 57,000 at ~100 volts of reverse bias. This gain can be attributed to avalanche multiplication of the photogenerated carriers within the device. Both of these devices show the potential of wide bandgap semiconductors for solar blind photo detectors. reprint
 
11.  
High-speed short wavelength infrared heterojunction phototransistors based on type II superlattices
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 (31 January 2020)-- 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·Hz½/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
 
12.  
High-speed free-space optical communications based on quantum cascade lasers and type-II superlattice detectors
High-speed free-space optical communications based on quantum cascade lasers and type-II superlattice detectors
Stephen M. Johnson; Emily Dial; M. Razeghi
Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128814 (31 January 2020)-- January 31, 2020
Free-space optical communications (FSOC) is a promising avenue for point-to-point, high-bandwidth, and high-security communication links. It has the potential to solve the “last mile” problem modern communication systems face, allowing for high-speed communication links without the expensive and expansive infrastructure required by fiber optic and wireless technologies 1 . Although commercial FSOC systems currently exist, due to their operation in the near infrared and short infrared ranges, they are necessarily limited by atmospheric absorption and scattering losses 2 . Mid-infrared (MWIR) wavelengths are desirable for free space communications systems because they have lower atmospheric scattering losses compared to near-infrared communication links. This leads to increased range and link uptimes. Since this portion of the EM spectrum is unlicensed, link establishment can be implemented quickly. Quantum cascade lasers (QCL) are ideal FSOC transmitters because their emission wavelength is adjustable to MWIR 3 . Compared to the typical VCSEL and laser diodes used in commercial NIR and SWIR FSOC systems, however, they require increased threshold and modulation currents 4 . Receivers based on type-II superlattice (T2SL) detectors are desired in FSOC for their low dark current, high temperature operation, and band gap tunable to MWIR 5. In this paper, we demonstrate the implementation of a high-speed FSOC system using a QCL and a T2SL detector. reprint
 
13.  
Gas sensing spectroscopy system utilizing a sample grating distributed feedback quantum cascade laser array and type II superlattice detector
Gas sensing spectroscopy system utilizing a sample grating distributed feedback quantum cascade laser array and type II superlattice detector
Nathaniel R. Coirier; Andrea I. Gomez-Patron; Manijeh Razeghi
Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128815 (31 January 2020)-- January 31, 2020
Gas spectroscopy is a tool that can be used in a variety of applications. One example is in the medical field, where it can diagnose patients by detecting biomarkers in breath, and another is in the security field, where it can safely alert personnel about ambient concentrations of dangerous gas. In this paper, we document the design and construction of a system compact enough to be easily deployable in defense, healthcare, and chemical safety environments. Current gas sensing systems use basic quantum cascade lasers (QCLs) or distributed feedback quantum cascade lasers (DFB QCLs) with large benchtop signal recovery systems to determine gas concentrations. There are significant issues with these setups, namely the lack of laser tunability and the lack of practicality outside of a very clean lab setting. QCLs are advantageous for gas sensing purposes because they are the most efficient lasers at the mid infrared region (MIR). This is necessary since gases tend to have stronger absorption lines in the MIR range than in the near-infrared (NIR) region. To incorporate the efficiency of a QCL with wide tuning capabilities in the MIR region, sampled grating distributed feedback (SGDFB) QCLs are the answer as they have produced systems that are widely tunable, which is advantageous for scanning a robust and complete absorption spectrum. The system employs a SGDFB QCL array emitter, a Type II InAsSb Superlattice detector receiver, a gas cell, and a cooling system. reprint
 
14.  
High speed type-II superlattice based photodetectors transferred on sapphire
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
 
15.  
Room temperature continuous wave THz frequency comb based on quantum cascade lasers
Room temperature continuous wave THz frequency comb based on quantum cascade lasers
M. Razeghi; Q. Y. Lu; F. H. Wang; D. H. Wu; S. Slivken
Proc. SPIE 11124, Terahertz Emitters, Receivers, and Applications X, 1112407 (6 September 2019) -- September 6, 2019
Frequency combs, spectra of phase-coherent equidistant lines, have revolutionized time and frequency metrology. The recently developed quantum cascade laser (QCL) comb has exhibits great potential with high power and broadband spectrum. However, in the terahertz (THz) range, cryogenic cooling has to be applied for THz QCL combs. We report a room temperature THz frequency comb at 3.0 THz based on difference-frequency generation from a mid-IR QCL comb. A largely detuned distributed-feedback grating is integrated into the QCL cavity to provide the single mode operation as well as enhanced spatial hole-burning effect for multimode comb operation. Multiheterodyne spectroscopy with multiple equally spaced lines by beating it with a reference Fabry-Pérot comb confirms the THz comb operation. This type of THz comb provides a new solution to chip-based high-speed high-resolution THz spectroscopy with compact size at room temperature. reprint
 
16.  
MOCVD grown β-Ga<sub>2</sub>O<sub>3</sub> metal-oxide-semiconductor field effect transistors on sapphire
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 (2019)-- 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<sub>1-x</sub>Sb<sub>x</sub> superlattice grown by metal-organic chemical vapor deposition
Demonstration of mid-wavelength infrared nBn photodetectors based on type-II InAs/InAs1-xSbx 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/InAs1-xSbx superlattice on a GaSb substrate grown by metal-organic chemical vapor deposition. An InAs/AlAs1-ySby/InAs/InAs1-xSbx 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·Hz1/2/W. reprint
 
18.  
Ga<sub>2</sub>O<sub>3</sub> Metal-oxide-semiconductor Field Effect Transistors on Sapphire Substrate by MOCVD
Ga2O3 Metal-oxide-semiconductor Field Effect Transistors on Sapphire Substrate by MOCVD
Ji-Hyeon Park, Ryan McClintock and Manijeh Razeghi
Semiconductor Science and Technology, Volume 34, Number 8-- June 26, 2019
Si-doped gallium oxide (Ga2O3) thin films were grown on a c-plane sapphire substrate by metalorganic chemical vapor deposition (MOCVD) and fabricated into metal oxide semiconductor field effect transistors (MOSFETs). The Ga2O3 MOSFETs exhibited effective gate modulation of the drain current with a complete channel pinch-off for VG < −25 V, and the three-terminal off-state breakdown voltage was 390 V. The device shows a very low gate leakage current (~50 pA/mm), which led to a high on/off ratio of ~108. These transistor characteristics were stable from room temperature to 250 °C reprint
 
19.  
AlGaN/AlN MOVPE heteroepitaxy: pulsed co-doping SiH4 and TMIn
AlGaN/AlN MOVPE heteroepitaxy: pulsed co-doping SiH4 and TMIn
Ilkay Demir, Yusuf Koçak, A. Emre Kasapoğlu, Manijeh Razeghi, Emre Gür and Sezai Elagoz
Semicond. Sci. Technol. 34 075028-- June 24, 2019
We report a new growth approach pulsed co-doping growth of AlxGa1−xN (x > 0.5) epilayers on AlN/Al2O3 templates by metal organic vapor phase epitaxy (MOVPE). Using this approach SiH4 (silane) and TMIn (trimethylindium) supplied to the growth chamber alternately and pulsed during the growth of AlGaN epilayers. Structural and morphological quality of AlGaN epilayers were investigated by high resolution x-ray diffraction (HR-XRD), atomic force microscopy (AFM), Raman spectroscopy, and scanning electron microscopy (SEM) techniques. It has shown that higher crystalline quality with low full width at half maximum (FWHM) and smoother surface morphology with reduced hexagonal hillock density has been obtained by the pulsed co-doping growth approach. Volcano like hillock structures has been confirmed by Raman mapping. reprint
 
20.  
Room temperature terahertz semiconductor frequency comb
Room temperature terahertz semiconductor frequency comb
Quanyong Lu, Feihu Wang, Donghai Wu, Steven Slivken & Manijeh Razeghi
Nature Communications 10, 2403 (2019)-- June 3, 2019
A terahertz (THz) frequency comb capable of high-resolution measurement will significantly advance THz technology application in spectroscopy, metrology and sensing. The recently developed cryogenic-cooled THz quantum cascade laser (QCL) comb has exhibited great potentials with high power and broadband spectrum. Here, we report a room temperature THz harmonic frequency comb in 2.2 to 3.3 THz based on difference-frequency generation from a mid-IR QCL. The THz comb is intracavity generated via down-converting a mid-IR comb with an integrated mid-IR single mode based on distributed-feedback grating without using external optical elements. The grating Bragg wavelength is largely detuned from the gain peak to suppress the grating dispersion and support the comb operation in the high gain spectral range. Multiheterodyne spectroscopy with multiple equally spaced lines by beating it with a reference Fabry-Pérot comb confirms the THz comb operation. This type of THz comb will find applications to room temperature chip-based THz spectroscopy. reprint
 
21.  
Investigation of surface leakage reduction for small pitch shortwave infrared photodetectors
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
 
22.  
High-power, continuous-wave, phase-locked quantum cascade laser arrays emitting at 8 μm
High-power, continuous-wave, phase-locked quantum cascade laser arrays emitting at 8 μm
WENJIA ZHOU,QUAN-YONG LU,DONG-HAI WU, STEVEN SLIVKEN, AND MANIJEH RAZEGHI
OPTICS EXPRESS 27, 15776-15785 (2019)-- May 20, 2019
We report a room-temperature eight-element phase-locked quantum cascade laser array emitting at 8 μm with a high continuous-wave power of 8.2 W and wall plug efficiency of 9.5%. The laser array operates primarily via the in-phase supermode and has single-mode emission with a side-mode suppression ratio of ~20 dB. The quantum cascade laser active region is based on a high differential gain (8.7 cm/kA) and low voltage defect (90 meV) design. A record high wall plug efficiency of 20.4% is achieved from a low loss buried ridge type single-element Fabry-Perot laser operating in pulsed mode at 20 °C. reprint
 
23.  
Extended short wavelength infrared heterojunction phototransistors based on type II superlattices
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·Hz½/W at 300 K which remains constant over a broad range of wavelengths and applied biases. reprint
 
24.  
Antimonite-based gap-engineered type-II superlattice materials grown by MBE and MOCVD for the third generation of infrared imagers
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
 
25.  
Type–II superlattices base visible/extended short–wavelength infrared photodetectors with a bandstructure–engineered photo–generated carrier extractor
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 (2019) -- 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·Hz½W-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·Hz½/W reprint
 

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