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76.  
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-- 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
 
77.  
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
 
78.  
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
 
79.  
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, 105400A-- 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
 
80.  
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, Vol.10, No.4, pp. 87-151-- 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
 
81.  
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
 
82.  
A lifetime of contributions to the world of semiconductors using the Czochralski invention
A lifetime of contributions to the world of semiconductors using the Czochralski invention
Manijeh Razeghi
Journal of Vacuum Volume 146, Pages 308-328-- December 1, 2017
Over the course of my career, I have made numerous contributions related to semiconductor crystal growth and high performance optoelectronics over a vast region of the electromagnetic spectrum (ultraviolet to terahertz). In 2016 this cumulated in my receiving the Jan Czochralski Gold Medal award from the European Materials Research Society. This article is designed to provide a historical perspective and general overview of these scientific achievements, on the occasion of being honored by this award. These achievements would not have been possible without high quality crystalline substrates, and this article is written in honor of Jan Czochralski on the 100th anniversary of his important discovery. reprint
 
83.  
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-- 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
 
84.  
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-- 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
 
85.  
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), p. 1228-- 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
 
86.  
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 Vol. 56, No. 31 -- 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
 
87.  
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-- 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
 
88.  
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, 993406-1-- 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
 
89.  
Radiative recombination of confined electrons at the MgZnO/ ZnO heterojunction interface
Radiative recombination of confined electrons at the MgZnO/ ZnO heterojunction interface
Sumin Choi, David J. Rogers, Eric V. Sandana, Philippe Bove, Ferechteh H. Teherani, Christian Nenstiel, Axel Hoffmann, Ryan McClintock, Manijeh Razeghi, David Look, Angus Gentle, Matthew R. Phillips & Cuong Ton-That
Nature Scientific Reports 7, pp. 7457-- August 7, 2017
We investigate the optical signature of the interface in a single MgZnO/ZnO heterojunction, which exhibits two orders of magnitude lower resistivity and 10 times higher electron mobility compared with the MgZnO/Al2O3 film grown under the same conditions. These impressive transport properties are attributed to increased mobility of electrons at the MgZnO/ZnO heterojunction interface. Depthresolved cathodoluminescence and photoluminescence studies reveal a 3.2 eV H-band optical emission from the heterointerface, which exhibits excitonic properties and a localization energy of 19.6 meV. The emission is attributed to band-bending due to the polarization discontinuity at the interface, which leads to formation of a triangular quantum well and localized excitons by electrostatic coupling. reprint
 
90.  
High peak power 16 m InP-related quantum cascade laser
High peak power 16 m InP-related quantum cascade laser
A. Szerlinga,∗, S. Slivkenb, M. RazeghibaInstytut
Opto-Electronics Review 25, pp. 205–208-- July 22, 2017
tIn this paper ∼16 μm-emitting multimode InP-related quantum cascade lasers are presented with themaximum operating temperature 373 K, peak and average optical power equal to 720 mW and 4.8 mW at 303 K, respectively, and the characteristic temperature (T0) 272 K. Two types of the lasers were fabricatedand characterized: the lasers with a SiO2 layer left untouched in the area of the metal-free window ontop of the ridge, and the lasers with the SiO2layer removed from the metal-free window area. Dual-wavelength operation was obtained, at ∼15.6 μm (641 cm−1) and at ∼16.6 μm (602 cm−1) for laserswith SiO2-removed, while within the emission spectrum of the lasers with SiO2-left untouched only the former lasing peak was present. The parameters of these devices like threshold current, optical power and emission wavelength are compared. Lasers without the SiO2 layer showed ∼15% lower threshold current than these ones with the SiO2 layer. The optical powers for lasers without SiO2 layer were almost twice higher than for the lasers with the SiO2 layer on the top of the ridge. reprint
 
91.  
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
 
92.  
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 136, pp. 51-54-- 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
 
93.  
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
Nature Scientific Reports 7, Article number: 3379-- 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
 
94.  
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
 
95.  
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
 
96.  
Recent advances in InAs/InAs1- xSbx/AlAs1-xSbx gap-engineered Type-II superlattice-based photodetectors
Recent advances in InAs/InAs1- xSbx/AlAs1-xSbx gap-engineered Type-II superlattice-based photodetectors
Manijeh Razeghi, Abbas Haddadi, Arash Dehzangi, Romain Chevallier, Thomas Yang
Proc. 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
 
97.  
Nanoselective area growth of defect-free thick indium-rich InGaN nanostructures on sacrificial ZnO templates
Nanoselective area growth of defect-free thick indium-rich InGaN nanostructures on sacrificial ZnO templates
Renaud Puybaret, David J Rogers, Youssef El Gmili, Suresh Sundaram, Matthew B Jordan, Xin Li, Gilles Patriarche, Ferechteh H Teherani, Eric V Sandana, Philippe Bove, Paul L Voss, Ryan McClintock, Manijeh Razeghi, Ian Ferguson, Jean-Paul Salvestrini, and Abdallah Ougazzade
Nanotechnology 28 195304-- April 29, 2017
Nanoselective area growth (NSAG) by metal organic vapor phase epitaxy of high-quality InGaN nanopyramids on GaN-coated ZnO/c-sapphire is reported. Nanopyramids grown on epitaxial low-temperature GaN-on-ZnO are uniform and appear to be single crystalline, as well as free of dislocations and V-pits. They are also indium-rich (with homogeneous 22% indium incorporation) and relatively thick (100 nm). These properties make them comparable to nanostructures grown on GaN and AlN/Si templates, in terms of crystallinity, quality, morphology, chemical composition and thickness. Moreover, the ability to selectively etch away the ZnO allows for the potential lift-off and transfer of the InGaN/GaN nanopyramids onto alternative substrates, e.g. cheaper and/or flexible. This technology offers an attractive alternative to NSAG on AlN/Si as a platform for the fabrication of high quality, thick and indium-rich InGaN monocrystals suitable for cheap, flexible and tunable light-emitting diodes. reprint
 
98.  
Dispersion compensated mid-infrared quantum cascade laser frequency comb with high power output
Dispersion compensated mid-infrared quantum cascade laser frequency comb with high power output
Q. Y. Lu, S. Manna, S. Slivken, D. H. Wu, and M. Razeghi
AIP Advances 7, 045313 -- April 26, 2017
Chromatic dispersion control plays an underlying role in optoelectronics and spectroscopy owing to its enhancement to nonlinear interactions by reducing the phase mismatching. This is particularly important to optical frequency combs based on quantum cascade lasers which require negligible dispersions for efficient mode locking of the dispersed modes into equally spaced comb modes. Here, we demonstrated a dispersion compensated mid-IR quantum cascade laser frequency comb with high power output at room temperature. A low-loss dispersive mirror has been engineered to compensate the device’s dispersion residue for frequency comb generation. Narrow intermode beating linewidths of 40 Hz in the comb-working currents were identified with a high power output of 460 mW and a broad spectral coverage of 80 cm-1. This dispersion compensation technique will enable fast spectroscopy and high-resolution metrology based on QCL combs with controlled dispersion and suppressed noise. reprint
 
99.  
Direct growth of thick AlN layers on nanopatterned Si substrates by cantilever epitaxy
Direct growth of thick AlN layers on nanopatterned Si substrates by cantilever epitaxy
Ilkay Demir, Yoann Robin, Ryan McClintock, Sezai Elagoz, Konstantinos Zekentes, and Manijeh Razeghi
Physica Status Solidi 214 (4), pp. 1770120-- April 4, 2017
The growth of thick, high quality, and low stress AlN films on Si substrates is highly desired for a number of applications like the development of micro and nano electromechanical system (MEMS and NEMS) technologies [1] and particularly for fabricating AlGaNbased UV LEDs [2–5]. UV LEDs are attractive as they are applied in many areas, such as biomedical instrumentations and dermatology, curing of industrial resins and inks, air purification, water sterilization, and many others [2, 3]. UV LEDs have been generally fabricated on AlN, GaN, Al2O3, or SiC substrates because of better lattice mismatching to AlGaN material systems. reprint
 
100.  
Imprinting of Nanoporosity in Lithium-Doped Nickel Oxide through the use of Sacrificial Zinc Oxide Nanotemplates
Imprinting of Nanoporosity in Lithium-Doped Nickel Oxide through the use of Sacrificial Zinc Oxide Nanotemplates
Vinod E. Sandana, David J. Rogers, Ferechteh H. Teheran1, Philippe Bove, Ryan McClintock and Manijeh Razeghi
Proc. SPIE 10105, Oxide-based Materials and Devices VIII, 101052C-- April 3, 2017
Methods for simultaneously increasing the conductivity and the porosity of NiO layers grown by pulsed laser deposition (PLD) were investigated in order to develop improved photocathodes for p-DSSC applications. NiO:Li (20at%) layers grown on c-Al2O3 by PLD showed a sharp drop in conductivity with increasing substrate temperature. Layers grown at room temperature were more than two orders of magnitude more conductive than undoped NiO layers but did not show evidence of any porosity in Scanning Electron Microscope (SEM) images. A new method for imposing a nanoporosity in NiO was developed based on a sacrificial template of nanostructured ZnO. SEM images and EDX spectroscopy showed that a nanoporous morphology had been imprinted in the NiO overlayer after preferential chemical etching away of the nanostructured ZnO underlayer. Beyond p-DSSC applications, this new process could represent a new paradigm for imprinting porosity in a whole range of materials. reprint
 

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