Publications by    
Page 1 of 28:  1  2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28  >> Next  (698 Items)

1.  
Demonstration of long wavelength infrared Type-II InAs/InAs<sub>1-x</sub>Sb<sub>x</sub> superlattices photodiodes on GaSb substrate grown by metalorganic chemical vapor deposition
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 (2018)-- June 12, 2018
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
 
2.  
Monolithic, steerable, mid-infrared laser realized with no moving parts
Monolithic, steerable, mid-infrared laser realized with no moving parts
Slivken S, Wu D, Razeghi M
Scientific Reports 7, 8472 -- May 24, 2018
The mid-infrared (2.5 < λ < 25 μm) spectral region is utilized for many purposes, such as chemical/biological sensing, free space communications, and illuminators/countermeasures. Compared to near-infrared optical systems, however, mid-infrared component technology is still rather crude, with isolated components exhibiting limited functionality. In this manuscript, we make a significant leap forward in mid-infrared technology by developing a platform which can combine functions of multiple mid-infrared optical elements, including an integrated light source. In a single device, we demonstrate wide wavelength tuning (240 nm) and beam steering (17.9 degrees) in the mid-infrared with a significantly reduced beam divergence (down to 0.5 degrees). The architecture is also set up to be manufacturable and testable on a wafer scale, requiring no cleaved facets or special mirror coating to function.
 
3.  
Phase-locked, high power, mid-infrared quantum cascade laser array
Phase-locked, high power, mid-infrared quantum cascade laser array
W. Zhou, S. Slivken, and M. Razeghi
Applied Physics Letters 112, 181106-- May 4, 2018
We demonstrate phase-locked, high power quantum cascade laser arrays, which are combined using a monolithic, tree array multimode interferometer, with emission wavelengths around 4.8 μm. A maximum output power of 15 W was achieved from an eight-element laser array, which has only a slightly higher threshold current density and a similar slope efficiency compared to a Fabry-Perot laser of the same length. Calculated multimode interferometer splitting loss is on the order of 0.27 dB for the in-phase supermode. In-phase supermode operation with nearly ideal behavior is demonstrated over the working current range of the array. reprint
 
4.  
Shortwave quantum cascade laser frequency comb for multi-heterodyne spectroscopy
Shortwave quantum cascade laser frequency comb for multi-heterodyne spectroscopy
Q. Y. Lu, S. Manna, D. H. Wu, S. Slivken, and M. Razeghi
Appl. Phys. Lett. 112, 141104-- April 3, 2018
Quantum cascade lasers (QCLs) are versatile light sources with tailorable emitting wavelengths covering the mid-infrared and terahertz spectral ranges. When the dispersion is minimized, frequency combs can be directly emitted from quantum cascade lasers via four-wave mixing. To date, most of the mid-infrared quantum cascade laser combs are operational in a narrow wavelength range wherein the QCL dispersion is minimal. In this work, we address the issue of very high dispersion for shortwave QCLs and demonstrate 1-W dispersion compensated shortwave QCL frequency combs at λ~5.0 μm, spanning a spectral range of 100 cm-1. The multi-heterodyne spectrum exhibits 95 equally spaced frequency comb lines, indicating that the shortwave QCL combs are ideal candidates for high-speed high-resolution spectroscopy reprint
 
5.  
The new oxide paradigm for solid state ultraviolet photodetectors
The new oxide paradigm for solid state ultraviolet photodetectors
D. J. Rogers, P. Bove, X. Arrateig, V. E. Sandana, F. H. Teherani, M. Razeghi, R. McClintock, E. Frisch, S. Harel,
Proceedings Volume 10533, Oxide-based Materials and Devices IX; 105331P-- March 22, 2018
The bandgap of wurzite ZnO layers grown on 2 inch diameter c-Al2O3 substrates by pulsed laser deposition was engineered from 3.7 to 4.8 eV by alloying with Mg. Above this Mg content the layers transformed from single phase hcp to mixed hcp/fcc phase before becoming single phase fcc above a bandgap of about 5.5 eV. Metal-Semiconductor-Metal (MSM) photodetectors based on gold Inter-Digitated-Transducer structures were fabricated from the single phase hcp layers by single step negative photolithography and then packaged in TO5 cans. The devices gave over 6 orders of magnitude of separation between dark and light signal with solar rejection ratios (I270 : I350) of over 3 x 105 and dark signals of 300 pA (at a bias of -5V). Spectral responsivities were engineered to fit the “Deutscher Verein des Gas- und Wasserfaches” industry standard form and gave over two decade higher responsivities (14 A/W, peaked at 270 nm) than commercial SiC based devices. Homogeneous Ga2O3 layers were also grown on 2 inch diameter c-Al2O3 substrates by PLD. Optical transmission spectra were coherent with a bandgap that increased from 4.9 to 5.4 eV when film thickness was decreased from 825 to 145 nm. X-ray diffraction revealed that the films were of the β-Ga2O3 (monoclinic) polytype with strong (-201) orientation. β-Ga2O3 MSM photodetectors gave over 4 orders of magnitude of separation between dark and light signal (at -5V bias) with dark currents of 250 pA and spectral responsivities of up to 40 A/W (at -0.75V bias). It was found that the spectral responsivity peak position could be decreased from 250 to 230 nm by reducing film thickness from 825 to 145 nm. This shift in peak responsivity wavelength with film thickness (a) was coherent with the apparent bandgap shift that was observed in transmission spectroscopy for the same layers and (b) conveniently provides a coverage of the spectral region in which MgZnO layers show fcc/hcp phase mixing. reprint
 
6.  
Room temperature operation of In<sub>x</sub>Ga<sub>1-x</sub>Sb/InAs type-II quantum well infrared photodetectors grown by MOCVD
Room temperature operation of InxGa1-xSb/InAs type-II quantum well infrared photodetectors grown by MOCVD
D. H. Wu, Y. Y. Zhang, and M. Razeghi
Applied Physics Letters 112, 111103 (2018)-- March 14, 2018
We demonstrate room temperature operation of In0.5Ga0.5Sb/InAs type-II quantum well photodetectors on InAs substrate grown by metal-organic chemical vapor deposition. At 300 K, the detector exhibits a dark current density of 0.12 A/cm2, peak responsivity of 0.72 A/W corresponding to a quantum efficiency of 23.3%, with calculated specific detectivity of 2.4×109 cm.Hz1/2/W at 3.81 μm. reprint
 
7.  
A review of the growth, doping, and applications of β-Ga<sub>2</sub>O<sub>3</sub> thin films
A review of the growth, doping, and applications of β-Ga2O3 thin films
Manijeh Razeghi, Ji-Hyeon Park , Ryan McClintock, Dimitris Pavlidis, Ferechteh H. Teherani, David J. Rogers, Brenden A. Magill, Giti A. Khodaparast, Yaobin Xu, Jinsong Wu, Vinayak P. Dravid
Proc. SPIE 10533, Oxide-based Materials and Devices IX, 105330R -- March 14, 2018
β-Ga2O3 is emerging as an interesting wide band gap semiconductor for solar blind photo detectors (SBPD) and high power field effect transistors (FET) because of its outstanding material properties including an extremely wide bandgap (Eg ~4.9eV) and a high breakdown field (8 MV/cm). This review summarizes recent trends and progress in the growth/doping of β-Ga2O3 thin films and then offers an overview of the state-of-the-art in SBPD and FET devices. The present challenges for β-Ga2O3 devices to penetrate the market in real-world applications are also considered, along with paths for future work. reprint
 
8.  
Thin-Film Antimonide-Based Photodetectors Integrated on Si
Thin-Film Antimonide-Based Photodetectors Integrated on Si
Yiyun Zhang , Member, IEEE, Abbas Haddadi, Member, IEEE, Romain Chevallier, Arash Dehzangi, Member, IEEE, and Manijeh Razeghi , Life Fellow, IEEE
IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 54, NO. 2-- February 21, 2018
Monolithic integration of antimonide (Sb)-based compound semiconductors on Si is in high demand to enrich silicon photonics by extending the detection range to longer infrared wavelengths. In this paper, we have demonstrated the damage-free transfer of large-area (1×1 cm² ) narrow-bandgap Sb-based type-II superlattice (T2SL)-based thin-film materials onto a Si substrate using a combination of wafer-bonding and chemical epilayer release techniques. An array of Sb-based T2SL-based long-wavelength infrared (LWIR) photodetectors with diameters from 100 to 400 μm has been successfully fabricated using standard "top–down" processing technique. The transferred LWIR photodetectors exhibit a cut-off wavelength of λ 8.6 μm at 77 K. The dark current density of the transferred photodetectors under 200 mV applied bias at 77 K is as low as 5.7×10−4 A/cm² and the R×A reaches 66.3 Ω·cm², exhibiting no electrical degradation compared with reference samples on GaSb native substrate. The quantum efficiency and peak responsivity at 6.75 μm (@77 K, 200 mV) are 46.2% and 2.44 A/W, respectively. The specific detectivity (D*) at 6.75 μm reaches as high as 1.6×1011 cm·Hz1/2/W under 200 mV bias at 77 K. Our method opens a reliable pathway to realize high performance and practical Sb-based optoelectronic devices on a Si platform. reprint
 
9.  
nBn extended short-wavelength infrared focal plane array
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 (2018)-- February 1, 2018
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
 
10.  
Type-II InAs/GaSb/AlSb superlatticebased heterojunction phototransistors: back to the future
Type-II InAs/GaSb/AlSb superlatticebased heterojunction phototransistors: back to the future
Abbas Haddadi, Arash Dehzangi, Romain Chevallier, Thomas Yang, Manijeh Razeghi
Proc. SPIE 10540, Quantum Sensing and Nano Electronics and Photonics XV- Page-1054004-1-- January 26, 2018
Most of reported HPTs in literatures are based on InGaAs compounds that cover NIR spectral region. However, InGaAs compounds provide limited cut-off wavelength tunability. In contrast, type-II superlattices (T2SLs) are a developing new material system with intrinsic advantages such as great flexibility in bandgap engineering, low growth and manufacturing cost, high-uniformity, auger recombination suppression, and high carrier effective mass that are becoming an attractive candidate for infrared detection and imaging from short-wavelength infrared to very long wavelength infrared regime. We present the recent advancements in T2SL-based heterojunction phototransistors in e– SWIR, MWIR and LWIR spectral ranges. A mid-wavelength infrared heterojunction phototransistor based on type-II InAs/AlSb/GaSb superlattices on GaSb substrate has been demonstrated. Then, we present the effect of vertical scaling on the optical and electrical performance of heterojunction phototransistors, where the performance of devices with different base width was compared as the base was scaled from 60 down to 40 nm. reprint
 
11.  
Dark current reduction in microjunction-based compound electron barrier type-II InAs/InAs1-xSbx superlattice-based long-wavelength infrared photodetectors
Dark current reduction in microjunction-based compound electron barrier type-II InAs/InAs1-xSbx superlattice-based long-wavelength infrared photodetectors
Romain Chevallier, Abbas Haddadi, Manijeh Razeghi
Proc. SPIE 10540, Quantum Sensing and Nano Electronics and Photonics XV Page. 1054007-1-- January 26, 2018
Reduction of dark current density in microjunction-based InAs/InAs1-xSbx type-II superlattice long-wavelength infrared photodetectors was demonstrated. A double electron barrier design was used to suppress both generation-recombination and surface dark currents. The photodetectors exhibited high surface resistivity after passivation with SiO2, which permits the use of small size features without having strong surface leakage current degrading the electrical performance. Fabricating a microjunction structure (25×25 μm² mesas with 10×10 μm² microjunctions) with this photodetector double barrier design results in a dark current density of 6.3×10-6 A/cm² at 77 K. The device has an 8 μm cut-off wavelength at 77 K and exhibits a quantum efficiency of 31% for a 2 μm-thick absorption region, which results in a specific detectivity value of 1.2×1012 cm·Hz1/2/W at 77 K. reprint
 
12.  
Broadband monolithically-tunable quantum cascade lasers
Broadband monolithically-tunable quantum cascade lasers
Wenjia Zhou, Ryan McClintock, Donghai Wu, Steven Slivken, Manijeh Razeghi
Proc. SPIE 10540, Quantum Sensing and Nano Electronics and Photonics XV,-- January 26, 2018
Mid-infrared lasers, emitting in the spectral region of 3-12 μm that contain strong characteristic vibrational transitions of many important molecules, are highly desirable for spectroscopy sensing applications. High efficiency quantum cascade lasers have been demonstrated with up to watt-level output power in the mid-infrared region. However, the wide wavelength tuning, which is critical for spectroscopy applications, is still largely relying on incorporating external gratings, which have stability issues. Here, we demonstrate the development a monolithic, widely tunable quantum cascade laser source emitting between 6.1 and 9.2 μm through an on-chip integration of a sampled grating distributed feedback tunable laser array with a beam combiner. A compact tunable laser system was built to drive the individual lasers within the array and coordinate the driving of the laser array to produce desired wavelength. A broadband spectral measurement (520cm-1) of methane shows excellent agreement with Fourier transform infrared spectrometer measurement. Further optimizations have led to high performance monolithic tunable QCLs with up to 65 mW output while delivering fundamental mode outputs. reprint
 
13.  
Recent progress of widely tunable, CW THz sources based QCLs at room temperature
Recent progress of widely tunable, CW THz sources based QCLs at room temperature
Manijeh Razeghi
Terahertz Science and Technology-- December 7, 2017
The THz spectral region is of significant interest to the scientific community, but is one of the hardest regions to access with conventional technology. A wide range of compelling new applications are initiating a new revolution in THz technology, especially with regard to the development of compact and versatile devices for THz emission and detection. In this article, recent advances with regard to III-V semiconductor optoelectronics are explored with emphasis on how these advances will lead to the next generation of THz component technology reprint
 
14.  
Progress in monolithic, broadband, widely tunable midinfrared quantum cascade lasers
Progress in monolithic, broadband, widely tunable midinfrared quantum cascade lasers
Manijeh Razeghi Wenjia Zhou Ryan McClintock Donghai Wu Steven Slivken
Optical Engineering 57(1), 011018-- December 1, 2017
We present recent progress on the development of monolithic, broadband, widely tunable midinfrared quantum cascade lasers. First, we show a broadband midinfrared laser gain realized by a heterogeneous quantum cascade laser based on a strain balanced composite well design of Al0.63In0.37As∕Ga0.35In0.65As∕ Ga0.47In0.53As. Single mode emission between 5.9 and 10.9 μm under pulsed mode operation was realized from a distributed feedback laser array, which exhibited a flat current threshold across the spectral range. Using the broadband wafer, a monolithic tuning between 6.2 and 9.1 μm was demonstrated from a beam combined sampled grating distributed feedback laser array. The tunable laser was utilized for a fast sensing of methane under pulsed operation. Transmission spectra were obtained without any moving parts, which showed excellent agreement to a standard measurement made by a Fourier transform infrared spectrometer. reprint
 
15.  
Type-II superlattice-based extended short-wavelength infrared focal plane array with an AlAsSb/GaSb superlattice etch-stop layer to allow near-visible light detection
Type-II superlattice-based extended short-wavelength infrared focal plane array with an AlAsSb/GaSb superlattice etch-stop layer to allow near-visible light detection
Romain Chevallier, Arash Dehzangi, Abbas Haddadi, and Manijeh Razeghi
Optics Letters Vol. 42, Iss. 21, pp. 4299-4302 (2017)-- October 17, 2017
A versatile infrared imager capable of imaging the near-visible to the extended short-wavelength infrared (e-SWIR) is demonstrated using e-SWIR InAs/GaSb/AlSb type-II superlattice-based photodiodes. A bi-layer etch-stop scheme consisting of bulk InAs0.91Sb0.09 and AlAs0.1Sb0.9/GaSb superlattice layers is introduced for substrate removal from the hybridized back-side illuminated photodetectors. The implementation of this new technique on an e-SWIR focal plane array results in a significant enhancement in the external quantum efficiency (QE) in the 1.8–0.8μm spectral region, while maintaining a high QE at wavelengths longer than 1.8μm. Test pixels exhibit 100% cutoff wavelengths of ∼2.1 and ∼2.25μm at 150 and 300K, respectively. They achieve saturated QE values of 56% and 68% at 150 and 300K, respectively, under back-side illumination and without any anti-reflection coating. At 150K, the photodetectors (27μm×27μm area) exhibit a dark current density of 4.7×10−7  A/cm2 under a −50  mV applied bias providing a specific detectivity of 1.77×1012  cm·Hz1/2/W. At 300K, the dark current density reaches 6.6×10−2  A/cm2 under −50 mV bias, providing a specific detectivity of 5.17×109  cm·Hz1/2/W. reprint
 
16.  
Bias-selectable three-color short-, extended-short-, and mid-wavelength infrared photodetectors based on type-II InAs/GaSb/AlSb superlattices
Bias-selectable three-color short-, extended-short-, and mid-wavelength infrared photodetectors based on type-II InAs/GaSb/AlSb superlattices
Abbas Haddadi, and Manijeh Razeghi
Optics Letters Vol. 42, Iss. 21, pp. 4275-4278 (2017)-- October 16, 2017
A bias-selectable, high operating temperature, three-color short-, extended-short-, and mid-wavelength infrared photodetector based on InAs/GaSb/AlSb type-II superlattices on GaSb substrate has been demonstrated. The short-, extended-short-, and mid-wavelength channels’ 50% cutoff wavelengths were 2.3, 2.9, and 4.4μm, respectively, at 150K. The mid-wavelength channel exhibited a saturated quantum efficiency of 34% at 4μm under +200 mV bias voltage in a front-side illumination configuration and without any antireflection coating. At 200mV, the device exhibited a dark current density of 8.7×10−5  A/cm2 providing a specific detectivity of ∼2×1011  cm·Hz1/2/W at 150K. The short-wavelength channel achieved a saturated quantum efficiency of 20% at 1.8μm. At −10  mV, the device’s dark current density was 5.5×10−8  A/cm2. At zero bias, its specific detectivity was 1×1011  cm·Hz1/2/W at 150K. The extended short-wavelength channel achieved a saturated quantum efficiency of 22% at 2.75 μm. Under −2  V bias voltage, the device exhibited a dark current density of 1.8×10−6  A/cm2 providing a specific detectivity of 6.3×1011  cm·Hz1/2/W at 150K. reprint
 
17.  
High performance monolithic, broadly tunable  mid-infrared quantum cascade lasers
High performance monolithic, broadly tunable mid-infrared quantum cascade lasers
WENJIA Zhou, DONGHAI Wu, RYAN McCLINTOCK, STEVEN SLIVKEN, AND MANIJEH RAZEGH1
Optica 4(10)-- October 10, 2017
Mid-infrared lasers, emitting in the spectral region of 3-12 µm that contains strong characteristic vibrational tran­sitions of many important molecules, are highly desirable for spectroscopy sensing applications. High-efficiency quantum cascade lasers have been demonstrated with up to watt-level output power in the mid-infrared region. However, the wide wavelength tuning that is critical for spectroscopy applica­tions still largely relies on incorporating external gratings, which have stability issues. Here, we demonstrate a mono­lithic, broadly tunable quantum cascade laser source emitting between 6.1 and 9.2 µm through an on-chip integration of a sampled grating distributed feedback tunable laser array and a beam combiner. High peak power up to 65 mW has been obtained through a balanced high-gain active region design, efficient waveguide layout, and the development of a broad­band antireflection coating. Nearly fundamental transverse­mode operation is achieved for all emission wavelengths with a pointing stability better than 1.6 mrad (0.1 °). The demon­strated laser source opens new opportunities for mid-infrared spectroscopy. reprint
 
18.  
Recent progress of quantum cascade laser research from 3 to 12 μm at the Center for Quantum Devices
Recent progress of quantum cascade laser research from 3 to 12 μm at the Center for Quantum Devices
MANIJEH RAZEGHI,* WENJIA ZHOU,STEVEN SLIVKEN,QUAN-YONG LU,DONGHAI WU, AND RYAN MCCLINTOC
Applied Optics -- October 10, 2017
The quantum cascade laser (QCL) is becoming the leading laser source in the mid-infrared (mid-IR) range, which contains two atmospheric transmission windows and many molecular fingerprint absorption features. Since its first demonstration in 1994, the QCL has undergone tremendous development in terms of the output power, wall plug efficiency, wavelength coverage, tunability and beam quality. At the Center for Quantum Devices, we have demonstrated high-power continuous wave operation of QCLs covering a wide wavelength range from 3 to 12 μm, with power output up to 5.1 W at room temperature. Recent research has resulted in power scaling in pulsed mode with up to 203 W output, electrically tunable QCLs based on monolithic sampled grating design, heterogeneous QCLs with a broad spectral gain, broadly tunable on-chip beam-combined QCLs, QCL-based mid-IR frequency combs, and fundamental mode surface emitting quantum cascade ring lasers. The developed QCLs will be the basis for a number of next-generation spectroscopy and sensing systems. reprint
 
19.  
Dark current reduction in microjunction-based double electron barrier type-II InAs/InAsSb superlattice long-wavelength infrared photodetectors
Dark current reduction in microjunction-based double electron barrier type-II InAs/InAsSb superlattice long-wavelength infrared photodetectors
Romain Chevallier, Abbas Haddadi, & Manijeh Razeghi
Scientific Reports 7, Article number: 12617 (2017)-- October 3, 2017
Microjunction InAs/InAsSb type-II superlattice-based long-wavelength infrared photodetectors with reduced dark current density were demonstrated. A double electron barrier design was employed to reduce both bulk and surface dark currents. The photodetectors exhibited low surface leakage after passivation with SiO2, allowing the use of very small size features without degradation of the dark current. Fabricating microjunction photodetectors (25 × 25 µm² diodes with 10 × 10 µm² microjunctions) in combination with the double electron barrier design results in a dark current density of 6.3 × 10−6 A/cm² at 77 K. The device has an 8 µm cut-off wavelength at 77 K and exhibits a quantum efficiency of 31% for a 2 µm-thick absorption region, which results in a specific detectivity value of 1.2 × 1012 cm·Hz½/W. reprint
 
20.  
RT-CW: widely tunable semiconductor THz QCL sources
RT-CW: widely tunable semiconductor THz QCL sources
M. Razeghi; Q. Y. Lu
Proceedings Volume 9934, Terahertz Emitters, Receivers, and Applications -- September 26, 2017
Distinctive position of Terahertz (THz) frequencies (ν~0.3 -10 THz) in the electromagnetic spectrum with their lower quantum energy compared to IR and higher frequency compared to microwave range allows for many potential applications unique to them. Especially in the security side of the THz sensing applications, the distinct absorption spectra of explosives and related compounds in the range of 0.1–5 THz makes THz technology a competitive technique for detecting hidden explosives. A compact, high power, room temperature continuous wave terahertz source emitting in a wide frequency range will greatly boost the THz applications for the diagnosis and detection of explosives. Here we present a new strong-coupled strain-balanced quantum cascade laser design for efficient THz generation based intracavity DFG. Room temperature continuous wave operation with electrical frequency tuning range of 2.06-4.35 THz is demonstrated reprint
 
21.  
Status of III-V semiconductor thin films and their applications to future OEICs
Status of III-V semiconductor thin films and their applications to future OEICs
Manijeh Razeghi
Proc. SPIE 10267, Integrated Optics and Optoelectronics, 102670T -- June 26, 2017
In the last decade, semiconductor technology has been advanced to a great extent in terms of electronic and photonic discrete devices. One of the main reasons for such a progress, is the result of advancement in the epitaxial growth techniques such as molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD), where device quality films can be grown with great control over composition, uniformity and thickness. MOCVD has proven to be one of the best growth methods for many IH-V semiconductor thin films 1. Its flexibility and potential to yield a broad range of growth rates resulted in the layers featuring the thicknesses from tens of microns down to several nanometers. Planar structures containing quantum wells with atomically flat interfaces, superlattices, strained or graded-index layers were successfully grown by MOCVD. Furthermore, MOCVD proved its efficiency in producing a laser devices by overgrowth and epitaxy on patterned substrates. The importance of MOCVD is strongly enhanced by the possibility of large-scale production by simultaneous growth on several substrates in one process. Several III-V semiconductor films with bandgaps ranging from infrared to ultraviolet (15 to 0.2 μm) have been successfully grown by MOCVD. reprint
 
22.  
Toward realization of small-size dual-band long-wavelength infrared photodetectors based on InAs/GaSb/AlSb type-II superlattices
Toward realization of small-size dual-band long-wavelength infrared photodetectors based on InAs/GaSb/AlSb type-II superlattices
Romain Chevallier, Abbas Haddadi, Manijeh Razeghi
Solid-State Electronics-- June 20, 2017
In this study, we demonstrate 12 × 12 µm² high-performance, dual-band, long-wavelength infrared (LWIR) photodetectors based on InAs/GaSb/AlSb type-II superlattices. The structure consists of two back-to-back heterojunction photodiodes with 2 µm-thick p-doped absorption regions. High quality dry etching combined with SiO2 passivation results in a surface resistivity value of 7.9 × 105 Ω·cm for the longer (red) channel and little degradation of the electrical performance. The device reaches dark current density values of 4.5 × 10−4 A/cm² for the longer (red) and 1.3 × 10−4 A/cm² for the shorter (blue) LWIR channels at quantum efficiency saturation. It has 50% cut-off wavelengths of 8.3 and 11.2 µm for the blue and red channel, respectively, at 77 K in back-side illumination configuration and exhibits quantum efficiencies of 37% and 29%, respectively. This results in specific detectivity values of 2.5 × 1011 cm·Hz½/W and 1.3 × 1011 cm·Hz½/W at 77 K. reprint
 
23.  
Bias–selectable nBn dual–band long–/very long–wavelength infrared photodetectors based on InAs/InAsSb/AlAsSb type–II superlattices
Bias–selectable nBn dual–band long–/very long–wavelength infrared photodetectors based on InAs/InAsSb/AlAsSb type–II superlattices
Abbas Haddadi, Arash Dehzangi, Romain Chevallier, Sourav Adhikary, & Manijeh Razeghi
Scientific Reports 7, Article number: 3379 (2017) -- June 13, 2017
Type–II superlattices (T2SLs) are a class of artificial semiconductors that have demonstrated themselves as a viable candidate to compete with the state–of–the–art mercury–cadmium–telluride material system in the field of infrared detection and imaging. Within type–II superlattices, InAs/InAs1−xSbx T2SLs have been shown to have a significantly longer minority carrier lifetime. However, demonstration of high–performance dual–band photodetectors based on InAs/InAs1−xSbx T2SLs in the long and very long wavelength infrared (LWIR & VLWIR) regimes remains challenging. We report the demonstration of high–performance bias–selectable dual–band long–wavelength infrared photodetectors based on new InAs/InAsSb/AlAsSb type–II superlattice design. Our design uses two different bandgap absorption regions separated by an electron barrier that blocks the transport of majority carriers to reduce the dark current density of the device. As the applied bias is varied, the device exhibits well–defined cut–off wavelengths of either ∼8.7 or ∼12.5 μm at 77 K. This bias–selectable dual–band photodetector is compact, with no moving parts, and will open new opportunities for multi–spectral LWIR and VLWIR imaging and detection. reprint
 
24.  
Broadband, Tunable, and Monolithic Quantum Cascade Lasers
Broadband, Tunable, and Monolithic Quantum Cascade Lasers
M. Razeghi, Q. Y. Lu, N. Bandyopadhyay, W. Zhou, D. Heydari, Y. Bai, and S. Slivken.
Semiconductor lasers; (140.3600) Lasers, tunable-- May 19, 2017
This article describes the state of research and recent developments related to broadband quantum cascade lasers. Monolithic tuning and system development is also discussed. reprint
 
25.  
Recent advances in antimonide-based gap-engineered Type-II superlattices material system for 2 and 3 colors infrared imagers
Recent advances in antimonide-based gap-engineered Type-II superlattices material system for 2 and 3 colors infrared imagers
Manijeh. Razeghi, Abbas Haddadi, Arash Dehzangi, Romain Chevallier, and Thomas Yang
Proceedings of SPIE 10177, Infrared Technology and Applications XLIII, 1017705-- May 9, 2017
InAs/InAs1-xSbx/AlAs1-xSbx type-II superlattices (T2SLs) is a system of multi-interacting quantum wells. Since its introduction, this material system has drawn a lot of attention especially for infrared detection. In recent years, InAs/InAs1- xSbx/AlAs1-xSbx T2SL material system has experienced incredible improvements in material quality, device structure designs and device fabrication process which elevated the performances of T2SL-based photodetectors to a comparable level to the state-of-the-art material systems for infrared detection such as Mercury Cadmium Telluride (MCT). In this paper, we will present the current status of InAs/InAs1-xSbx/AlAs1-xSbx T2SL-based photodetectors for detection in different infrared regions, from short-wavelength (SWIR) to long-wavelength (LWIR) infrared, and the future outlook of this material system. reprint
 

Page 1 of 28:  1  2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28  >> Next  (698 Items)