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108.  nBn extended short-wavelength infrared focal plane array
ARASH DEHZANGI, ABBAS HADDADI, ROMAIN CHEVALLIER, YIYUN ZHANG, AND MANIJEH RAZEGHI
Optics Letters Vol. 43, Issue 3, pp. 591-594-- February 1, 2018 ...[Visit Journal]
An extended short-wavelength nBn InAs/GaSb/AlSb type-II superlattice-based infrared focal plane array imager was demonstrated. A newly developed InAs0.10Sb0.90∕GaSb superlattice design was used as the large-bandgap electron barrier in this photodetector. The large band gap electron-barrier design in this nBn photodetector architecture leads to the device having lower dark current densities. A new bi-layer etch-stop scheme using a combination of InAs0.91Sb0.09 bulk and AlAs0.1Sb0.9∕GaSb superlattice layers was introduced to allow complete substrate removal and a shorter wavelength cut-on. Test pixels exhibit 100% cutoff wavelengths of ∼2.30 and ∼2.48 μm at 150 and 300 K, respectively. The devices achieve saturated quantum efficiency values of 59.7% and 63.8% at 150 and 300 K, respectively, under backside illumination and without any antireflection coating.At 150 K, photodetectors exhibit dark current density of 8.75 × 10−8 A∕cm² under −400 mV applied bias, providing specific detectivity of 2.82 × 1012 cm · Hz1∕2∕W at 1.78 μm. At 300 K, the dark current density reaches 4.75 × 10−2 A∕cm² under −200 mV bias, providing a specific detectivity of 8.55 × 109 cm · Hz1∕2∕W 1.78 μm. [reprint (PDF)]
 
89.  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 ...[Visit Journal]
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 (PDF)]
 
84.  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 ...[Visit Journal]
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 (PDF)]
 
63.  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 ...[Visit Journal]
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 (PDF)]
 
32.  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-- April 21, 2020 ...[Visit Journal]
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 (PDF)]
 
28.  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 ...[Visit Journal]
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 (PDF)]
 
20.  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 ...[Visit Journal]
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 (PDF)]
 
18.  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 ...[Visit Journal]
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 (PDF)]
 
17.  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 ...[Visit Journal]
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 (PDF)]
 
17.  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 ...[Visit Journal]
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 (PDF)]
 
17.  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 ...[Visit Journal]
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 (PDF)]
 
16.  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 ...[Visit Journal]
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 (PDF)]
 
15.  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-- May 4, 2020 ...[Visit Journal]
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 (PDF)]
 
15.  Harmonic injection locking of high-power mid-infrared quantum cascade lasers
Feihu Wang, Steven Slivken, and Manijeh Razeghi
OSA Photonics Research •https://doi.org/10.1364/PRJ.423573 ...[Visit Journal]
High-power, high-speed quantum cascade lasers (QCLs) with stable emission in the mid-infrared regime are of great importance for applications in metrology, telecommunication, and fundamental tests of physics. Owing to the inter-sub-band transition, the unique ultrafast gain recovery time of the QCL with picosecond dynamics is expected to overcome the modulation limit of classical semiconductor lasers and bring a revolution for the next generation of ultrahigh-speed optical communication. Therefore, harmonic injection locking, offering the possibility to fast modulate and greatly stabilize the laser emission beyond the rate limited by cavity length, is inherently adapted to QCLs. In this work, we demonstrate for the first time the harmonic injection locking of a mid-infrared QCL with an output power over 1 watt in continuous-wave operation at 288 K. Compared with an unlocked laser, the inter-mode spacing fluctuation of an injection locked QCL can be considerably reduced by a factor above 1×10 E3, which permits the realization of an ultra-stable mid-infrared semiconductor laser with high phase coherence and frequency purity. Despite temperature change, this fluctuation can be still stabilized to hertz level by a microwave modulation up to ∼18 GHz. These results open up the prospect of the applications of mid-infrared QCL technology for frequency comb engineering, metrology and the next generation ultrahigh-speed telecommunication. It may also stimulate new schemes for exploring ultrafast mid-infrared pulse generation in QCLs. [reprint (PDF)]
 
13.  Demonstration of long wavelength infrared Type-II InAs/InAs1-xSbx superlattices photodiodes on GaSb substrate grown by metalorganic chemical vapor deposition
D. H. Wu, A. Dehzangi, Y. Y. Zhang, M. Razeghi
Applied Physics Letters 112, 241103-- June 12, 2018 ...[Visit Journal]
We report the growth and characterization of long wavelength infrared type-II InAs/InAs1−xSbx superlattices photodiodes with a 50% cut-off wavelength at 8.0 μm on GaSb substrate grown by metalorganic chemical vapor deposition. At 77 K, the photodiodes exhibited a differential resistance at zero bias (R0A) 8.0 Ω·cm2, peak responsivity of 1.26 A/W corresponding to a quantum efficiency of 21%. A specific detectivity of 5.4×1010 cm·Hz1/2/W was achieved at 7.5 μm. [reprint (PDF)]
 
13.  High Thermal Stability of κ-Ga2O3 Grown by MOCVD
Junhee Lee, Honghyuk Kim, Lakshay Gautam and Manijeh Razeghi
Lee, J.; Kim, H.; Gautam, L.; Razeghi, M. High Thermal Stability of κ-Ga2O3 Grown by MOCVD. Crystals 2021, 11, 446. https://doi.org/ 10.3390/cryst11040446 ...[Visit Journal]
We report a high thermal stability of kappa gallium oxide grown on c-plane sapphire substrate by metal organic chemical vapor deposition. Kappa gallium oxide is widely known as a metastable polymorph transitioning its phase when subjected to a high temperature. Here, we show the kappa gallium oxide whose phase is stable in a high temperature annealing process at 1000 °C. These oxide films were grown at 690 °C under nitrogen carrier gas. The materials showed high electrical resistivity when doped with silicon, whereas the film conductivity was significantly improved when doped with both indium and silicon. This work provides a pathway to overcoming limitations for the advance in utilizing kappa gallium oxide possessing superior electrical characteristics. [reprint (PDF)]
 
12.  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 ...[Visit Journal]
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 (PDF)]
 
12.  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 ...[Visit Journal]
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 ·Hz½/W at 1.9μm. [reprint (PDF)]
 
12.  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 ...[Visit Journal]
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 (PDF)]
 
11.  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 ...[Visit Journal]
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 (PDF)]
 
11.  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-- February 25, 2020 ...[Visit Journal]
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 (PDF)]
 
11.  Sb-based third generation at Center for Quantum Devices
Razeghi, Manijeh
SPIE Proceedings Volume 11407, Infrared Technology and Applications XLVI; 114070T-- April 23, 2020 ...[Visit Journal]
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 (PDF)]
 
11.  Background–limited long wavelength infrared InAs/InAsSb type-II superlattice-based photodetectors operating at 110 K
Abbas Haddadi, Arash Dehzangi, Sourav Adhikary, Romain Chevallier, and Manijeh Razeghi
APL Materials 5, 035502 -- February 13, 2017 ...[Visit Journal]
We report the demonstration of high-performance long-wavelength infrared (LWIR) nBn photodetectors based on InAs/InAsSb type-II superlattices. A new saw-tooth superlattice design was used to implement the electron barrier of the photodetectors. The device exhibited a cut-off wavelength of ∼10 μm at 77 K. The photodetector exhibited a peak responsivity of 2.65 A/W, corresponding to a quantum efficiency of 43%. With an R × A of 664 Ω·cm² and a dark current density of 8 × 10−5 A/cm², under −80 mV bias voltage at 77 K, the photodetector exhibited a specific detectivity of 4.72 × 1011 Jones and a background–limited operating temperature of 110 K. [reprint (PDF)]
 
11.  Room temperature quantum cascade laser with ∼ 31% wall-plug efficiency
F. Wang, S. Slivken, D. H. Wu, and M. Razeghi
AIP Advances 10, 075012-- July 14, 2020 ...[Visit Journal]
In this article, we report the demonstration of a quantum cascade laser emitting at λ ≈ 4.9 μm with a wall-plug efficiency of ∼31% and an output power of ∼23 W in pulsed operation at room temperature with 50 cascade stages (Ns). With proper fabrication and packaging, this buried ridge quantum cascade laser with a cavity length of 5 mm delivers more than ∼15 W output power, and its wall-plug efficiency exceeds ∼20% at 100 °C. The experimental results of the lasers are well in agreement with the numerical predictions. [reprint (PDF)]
 
11.  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 ...[Visit Journal]
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 (PDF)]
 

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