Center for Quantum Devices - Most Downloaded Journal Articles

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24.	High-Average-Power, High-Duty-Cycle (~6 μm) Quantum Cascade Lasers S. Slivken, A. Evans, J. David, and M. Razeghi Virtual Journal of Nanoscience & Technology 9-- December 9, 2002 ...[Visit Journal][reprint (PDF)]
24.	High brightness angled cavity quantum cascade lasers D. Heydari, Y. Bai, N. Bandyopadhyay, S. Slivken, and M. Razeghi Applied Physics Letters 106, 091105-- March 6, 2015 ...[Visit Journal] A quantum cascade laser (QCL) with an output power of 203 W is demonstrated in pulsed mode at 283 K with an angled cavity. The device has a ridge width of 300 μm, a cavity length of 5.8 mm, and a tilt angle of 12°. The back facet is high reflection coated, and the front facet is anti-reflection coated. The emitting wavelength is around 4.8 μm. In distinct contrast to a straight cavity broad area QCL, the lateral far field is single lobed with a divergence angle of only 3°. An ultrahigh brightness value of 156 MW cm²·sr^-1 is obtained, which marks the brightest QCL to date. [reprint (PDF)]
24.	TEG IN LP-MO CVD Ga 0 4 7 ln 0 S3 As-lnP SUPERLATTICE M. RAZEGHIM. A. POISSONJ. P. LARIVAINB. de CREMOUXJ. P. DUCHEMIN ELECTRONICS LETTERs, 1982 ,Vol. 18-- April 15, 1982 ...[Visit Journal] We report the first successful growth of Ga o .4. 7 In 0 . J3 As-InPsuperlattice by the low-pressure metalorganic chemicalvapour deposition technique, and evidence for TEG proper-ties in these structures. [reprint (PDF)]
24.	Thermal imaging based on high-performance InAs/InP quantum-dot infrared photodetector operating at high temperature M. Razeghi; H. Lim; S. Tsao; H. Seo; W. Zhang Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS.15-16:[4382251] (2007).-- October 21, 2007 ...[Visit Journal] We report a room temperature operating and high-performance InAs quantum-dot infrared photodetector on InP substrate and thermal imaging of 320times256 focal plane array based on this device up to 200 K. [reprint (PDF)]
24.	Comprehensive study of blue and green multi-quantum-well light-emitting diodes grown on conventional and lateral epitaxial overgrowth GaN C. Bayram, J.L. Pau, R. McClintock and M. Razeghi Applied Physics B: Lasers and Optics, Vol. 95, p. 307-314-- November 29, 2008 ...[Visit Journal] Growths of blue and green multi-quantum wells (MQWs) and light-emitting diodes (LEDs) are realized on lateral epitaxial overgrowth (LEO) GaN, and compared with identical structures grown on conventional GaN. Atomic force microscopy is used to confirm the significant reduction of dislocations in the wing region of our LEO samples before active-region growth. Differences between surface morphologies of blue and green MQWs are analyzed. These MQWs are integrated into LEDs. All devices show a blue shift in the electroluminescence (EL) peak and narrowing in EL spectra with increasing injection current, both characteristics attributed to the band-gap renormalization. Green LEDs show a larger EL peak shift and a broader EL spectrum due to larger piezoelectric field and more indium segregation in the MQWs, respectively. Blue LEDs on LEO GaN show a higher performance than those on conventional GaN; however, no performance difference is observed for green LEDs on LEO GaN versus conventional GaN. The performance of the green LEDs is shown to be primarily limited by the active layer growth quality. [reprint (PDF)]
24.	Long Wavelength Type-II Photodiodes Operating at Room Temperature H. Mohseni and M. Razeghi IEEE Photonics Technology Letters 13 (5)-- May 1, 2001 ...[Visit Journal] The operation of uncooled InAs-GaSb superlattice photodiodes with a cutoff wavelength of λc=8 μm and a peak detectivity of 1.2 × 10⁸ cm·Hz^½/W at zero bias is demonstrated. The detectivity is similar to the best uncooled HgCdTe detectors and microbolometers. However, the R0A product is more than two orders of magnitude higher than HgCdTe and the device is more than four orders of magnitude faster than microbolometers. These features combined with their low 1/f noise and high uniformity make these type-II photodiodes an excellent choice for uncooled high-speed IR imaging arrays [reprint (PDF)]
23.	Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices with an AlAsSb/GaSb superlattice barrier A. Haddadi, R. Chevallier, A. Dehzangi, and M. Razeghi Applied Physics Letters 110, 101104-- March 8, 2017 ...[Visit Journal] Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices on GaSb substrate have been demonstrated. An AlAsSb/GaSb H-structure superlattice design was used as the large-bandgap electron-barrier in these photodetectors. The photodetector is designed to have a 100% cut-off wavelength of ∼2.8 μm at 300 K. The photodetector exhibited a room-temperature (300 K) peak responsivity of 0.65 A/W at 1.9 μm, corresponding to a quantum efficiency of 41% at zero bias under front-side illumination, without any anti-reflection coating. With an R × A of 78 Ω·cm² and a dark current density of 8 × 10⁻³ A/cm² under −400 mV applied bias at 300 K, the nBn photodetector exhibited a specific detectivity of 1.51 × 10¹⁰ Jones. At 150 K, the photodetector exhibited a dark current density of 9.5 × 10⁻⁹ A/cm² and a quantum efficiency of 50%, resulting in a detectivity of 1.12 × 10¹³ Jones. [reprint (PDF)]
23.	Room temperature terahertz semiconductor frequency comb Quanyong Lu, Feihu Wang, Donghai Wu, Steven Slivken & Manijeh Razeghi Nature Communications 10, 2403-- June 3, 2019 ...[Visit Journal] 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 (PDF)]
23.	Novel process for direct bonding of GaN onto glass substrates using sacrificial ZnO template layers to chemically lift-off GaN from c-sapphire Rogers, D. J.; Ougazzaden, A.; Sandana, V. E.; Moudakir, T.; Ahaitouf, A.; Teherani, F. Hosseini; Gautier, S.; Goubert, L.; Davidson, I. A.; Prior, K. A.; McClintock, R. P.; Bove, P.; Drouhin, H.-J.; Razeghi, M. Proc. SPIE 8263, Oxide-based Materials and Devices III, 82630R (February 9, 2012)-- February 9, 2012 ...[Visit Journal] GaN was grown on ZnO-buffered c-sapphire (c-Al₂O₃) substrates by Metal Organic Vapor Phase Epitaxy. The ZnO then served as a sacrificial release layer, allowing chemical lift-off of the GaN from the c-Al₂O₃ substrate via selective wet etching of the ZnO. The GaN was subsequently direct-wafer-bonded onto a glass substrate. X-Ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray microanalysis, Room Temperature Photoluminescence & optical microscopy confirmed bonding of several mm2 of crack-free wurtzite GaN films onto a soda lime glass microscope slide with no obvious deterioration of the GaN morphology. Using such an approach, InGaN based devices can be lifted-off expensive single crystal substrates and bonded onto supports with a better cost-performance profile. Moreover, the approach offers the possibility of reclaiming and reusing the substrate. [reprint (PDF)]
23.	Watt level performance of quantum cascade lasers in room temperature continuous wave operation at λ ∼ 3.76 μm N. Bandyopadhyay, Y. Bai, B. Gokden, A. Myzaferi, S. Tsao, S. Slivken and M. Razeghi Applied Physics Letters, Vol. 97, No. 13-- September 27, 2010 ...[Visit Journal] An InP-based quantum cascade laser heterostructure emitting at 3.76 μm is grown with gas-source molecular beam epitaxy. The laser core is composed of strain balanced In_0.76Ga_0.24As/In_0.26Al_0.74As. Pulsed testing at room temperature exhibits a low threshold current density (1.5 kA/cm²) and high wall plug efficiency (10%). Room temperature continuous wave operation gives 6% wall plug efficiency with a maximum output power of 1.1 W. Continuous wave operation persists up to 95 °C. [reprint (PDF)]
23.	Multi-color 4–20 μm In-P-based Quantum Well Infrared Photodetectors C. Jelen, S. Slivken, G.J. Brown, and M. Razeghi SPIE Conference, San Jose, CA, -- January 27, 1999 ...[Visit Journal] In order to tune the wavelength of lattice-matched QWIP detectors over the range from 4 - 20 &mum, new designs are demonstrated for the first time which combine InGaAlAs and InGaAsP layers lattice-matched to InP and grown by gas-source molecular beam epitaxy. We demonstrate the first long-wavelength quantum well infrared photodetectors using the lattice-matched n-doped InGaAlAs/InP materials system. Samples with AlAs mole fractions of 0.0, 0.1, and 0.15 result in cutoff wavelengths of 8.5, 13.3, and 19.4 μm, respectively. A 45 degree facet coupled illumination responsivity of R equals 0.37 A/W and detectivity of D*(λ) equals 1x10⁹ cm·Hz^½·W^-1 at T = 77 K, for a cutoff wavelength λ_c equals 13.3 μm have been achieved. Based on the measured intersubband photoresponse wavelength, a null conduction band offset is expected for In_0.52Ga_0.21Al_0.27As/InP heterojunctions. We also report quantum well infrared photodetector structures of In_0.53Ga_0.47As/Al_0.48In_0.52As grown on InP substrate with photoresponse at 4 μm suitable for mid-wavelength infrared detectors. These detectors exhibit a constant peak responsivity of 30 mA/W independent of temperature in the range from T equals 77 K to T equals 200 K. Combining these two materials, we report the first multispectral detectors that combine lattice-matched quantum wells of InGaAs/InAlAs and InGaAs/InP. Utilizing two contacts, a voltage tunable detector with (lambda) p equals 8 micrometer at a bias of V equals 5 V and λ_p equals 4 μm at V equals 10 V is demonstrated. [reprint (PDF)]
23.	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)]
23.	Type II superlattice infrared detectors and focal plane arrays Vaidya Nathan; Manijeh Razeghi Proc. SPIE 6542, Infrared Technology and Applications XXXIII, 654209 (May 14, 2007)-- May 14, 2007 ...[Visit Journal] Type II superlattce photodetectors have recently experienced significant improvements in both theoretical structure design and experimental realization. Empirical Tight Binding Method is initiated and developed for Type II superlattice. Growth characteristics such as group V segregation and incorporation phenomena are taken into account in the model and shown higher precision. A new Type II structure, called M-structure, is introduced and theoretically demonstrated high R₀A, high quantum efficiency. Device design is optimized to improve the performance. As a result, 55% quantum efficiency and 10 Ohm·cm² R₀A are achieved for an 11.7 μm cut-off photodetector at 77K. FPA imaging at longwavelength is demonstrated with a capability of imaging up to 171K. At 81K, the noise equivalent temperature difference presented a peak at 0.33K. [reprint (PDF)]
23.	EPR STUDY OF Mn 2. AROUND THE FERROELASTIC TRANSITION POINT OF Pb3(PO4)2 M. Razeghi, B. Houlier and M. Yuste M. Razeghi et al. EPR STUDY OF Mn 2. AROUND THE FERROELASTIC TRANSITION POINT OF Pb3(PO4)2, Solid State Communications, Vol. 26, pp. 665-668. -- January 26, 1978 ...[Visit Journal] The spin Hamiltonian parameters of Mn 2÷ have been measured above and below the transition point (180"C) of the lead phosphate. They show that Mn 2+ substitutes a Pbl ion. Between 175 and 180vC the principal axis OX of the fine tensor is parallel to the wave vector of the soft mode which condensates at the transition point. An exaltation of the linewidth is observed. The linewidth remains constant within 50C of Te; in this temperature range, the "static regime" is achieved, and the correlation time of the fluctuations is less than 10 -s sec. [reprint (PDF)]
23.	Room Temperature, Continuous Wave Quantum Cascade Laser Grown Directly on a Si Wafer Steven Slivken and Manijeh Razeghi S. Slivken and M. Razeghi,, Journal of Quantum Electronics, Vol. 59, No. 4, doi: 10.1109/JQE.2023.3282710 ...[Visit Journal] We report the room temperature demonstration of a high power, continuous wave, LWIR quantum cascade laser grown directly on a Si substrate. A new wafer, based on a high efficiency, strain-balanced laser core was processed into a lateral injection buried heterostructure laser geometry. A pulsed efficiency of 11.1% was demonstrated at room temperature, with an emission wavelength of 8.35 μm. With low fidelity, epilayer-up packaging, CW emission up to 343 K was also demonstrated, with a maximum output power of >0.7 W near room temperature. [reprint (PDF)]
23.	A lifetime of contributions to the world of semiconductors using the Czochralski invention M. Razeghi Vacuum Vol. 9934, 993406-1-- February 8, 2017 ...[Visit Journal] 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 (PDF)]
23.	High Power, Room Temperature InP-Based Quantum Cascade Laser Grown on Si Steven Slivken and Manijeh Razeghi Journal of Quantum Electronics, Vol. 58, No. 6, 2300206 ...[Visit Journal] We report on the realization of an InP-based long wavelength quantum cascade laser grown on top of a silicon substrate. This demonstration first required the development of an epitaxial template with a smooth surface, which combines two methods of dislocation filtering. Once wafer growth was complete, a lateral injection buried heterostructure laser geometry was employed for efficient current injection and low loss. The laser emits at a wavelength of 10.8 μm and is capable of operation above 373 K, with a high peak power (>4 W) at room temperature. Laser threshold behavior with temperature is characterized by a T0 of 178 K. The far field beam shape is single lobed, showing fundamental transverse mode operation. [reprint (PDF)]
23.	High power continuous operation of a widely tunable quantum cascade laser with an integrated amplifier S. Slivken, S. Sengupta, and M. Razeghi Applied Physics Letters 107, 251101-- December 21, 2015 ...[Visit Journal] Wide electrical tuning and high continuous output power is demonstrated from a single mode quantum cascade laser emitting at a wavelength near 4.8 μm. This is achieved in a space efficient manner by integrating an asymmetric sampled grating distributed feedback tunable laser with an optical amplifier. An initial demonstration of high peak power operation in pulsed mode is demonstrated first, with >5 W output over a 270 nm (113 cm⁻¹) spectral range. Refinement of the geometry leads to continuous operation with a single mode spectral coverage of 300 nm (120 cm⁻¹) and a maximum continuous power of 1.25 W. The output beam is shown to be nearly diffraction-limited, even at high amplifier current. [reprint (PDF)]
23.	Band-gap narrowing and potential fluctuation in Si-doped GaN I.H. Lee, J.J. Lee, P. Kung, F.J. Sanchez, and M. Razeghi Applied Physics Letters 74 (1)-- January 4, 1999 ...[Visit Journal] We investigate the optical properties of two sets of Si-doped GaN epitaxial layers with different degree of compensation. The electron concentration dependence of the band-gap energy measured by photoluminescence is interpreted as band-gap narrowing effect and evaluated by a simple relation. The photoluminescence peak positions of heavily compensated samples are shifted downward with respect to those of moderately compensated samples, and the down shift becomes larger at higher electron density. Based on analysis of photoluminescence spectra, these prominent behaviors are accounted for by band-edge potential fluctuation associated with inhomogeneous residual impurities. [reprint (PDF)]
23.	Quantum cascade lasers that emit more light than heat Y. Bai, S. Slivken, S. Kuboya, S.R. Darvish and M. Razeghi Nature Photonics, February 2010, Vol. 4, p. 99-102-- February 1, 2010 ...[Visit Journal] For any semiconductor lasers, the wall plug efficiency, that is, the portion of the injected electrical energy that can be converted into output optical energy, is one of the most important figures of merit. A device with a higher wall plug efficiency has a lower power demand and prolonged device lifetime due to its reduced self-heating. Since its invention, the power performance of the quantum cascade laser has improved tremendously. However, although the internal quantum efficiency can be engineered to be greater than 80% at low temperatures, the wall plug efficiency of a quantum cascade laser has never been demonstrated above 50% at any temperature. The best wall plug efficiency reported to date is 36% at 120 K. Here, we overcome the limiting factors using a single-well injector design and demonstrate 53% wall plug efficiency at 40 K with an emitting wavelength of 5 µm. In other words, we demonstrate a quantum cascade laser that produces more light than heat. [reprint (PDF)]
23.	Avalanche multiplication in AlGaN based solar-blind photodetectors R. McClintock, A. Yasan, K. Minder, P. Kung, and M. Razeghi Applied Physics Letters, 87 (24)-- December 12, 2005 ...[Visit Journal] Avalanche multiplication has been observed in solar-blind AlGaN-based p-i-n photodiodes. Upon ultraviolet illumination, the optical gain shows a soft breakdown starting at relatively low electric fields, eventually saturating without showing a Geiger mode breakdown. The devices achieve a maximum optical gain of 700 at a reverse bias of 60 V. By modeling the device, it is found that this corresponds to an electric-field strength of 1.7 MV/cm. [reprint (PDF)]
23.	Widely tuned room temperature terahertz quantum cascade laser sources based on difference-frequency generation Q.Y. Lu, N. Bandyopadhyay, S. Slivken, Y. Bai and M. Razeghi Applied Physics Letters, Vol. 101, No. 25, p. 251121-1-- December 17, 2012 ...[Visit Journal] We demonstrate room temperature THz quantum cascade laser sources with a broad spectral coverage based on intracavity difference-frequency generation. Two mid-infrared active cores based on the single-phonon resonance scheme are designed with a THz nonlinearity specially optimized at the high operating fields that correspond to the highest mid-infrared output powers. A Čerenkov phase-matching scheme along with integrated dual-period distributed feedback gratings are used for efficient THz extraction and spectral purification. Single mode emissions from 1.0 to 4.6 THz with a side-mode suppression ratio and output power up to 40 dB and 32 μW are obtained, respectively. [reprint (PDF)]
23.	Solar-blind avalanche photodiodes R. McClintock, K. Minder, A. Yasan, C. Bayram, F. Fuchs, P. Kung and M. Razeghi SPIE Conference, San Jose, CA, Vol. 6127, pp. 61271D-- January 23, 2006 ...[Visit Journal] There is a need for semiconductor based UV photodetectors to support avalanche gain in order to realize better performance and more effectively compete with existing photomultiplier tubes. However, there are numerous technical issues associated with the realization of high-quality solar-blind avalanche photodiodes (APDs). In this paper, APDs operating at 280 nm, within the solar-blind region of the ultraviolet spectrum, are investigated. [reprint (PDF)]
23.	Aluminum gallium nitride short-period superlattices doped with magnesium A. Saxler, W.C. Mitchel, P. Kung and M. Razeghi Applied Physics Letters 74 (14)-- April 9, 1999 ...[Visit Journal] Short-period superlattices consisting of alternating layers of GaN:Mg and AlGaN:Mg were grown by low-pressure organometallic vapor phase epitaxy. The electrical properties of these superlattices were measured as a function of temperature and compared to conventional AlGaN:Mg layers. It is shown that the optical absorption edge can be shifted to shorter wavelengths while lowering the acceptor ionization energy by using short-period superlattice structures instead of bulk-like AlGaN:Mg. [reprint (PDF)]
23.	Low Dark Current Deep UV AlGaN Photodetectors on AlN Substrate Lakshay Gautam, Junhee Lee, Gail Brown, Manijeh Razeghi IEEE Journal of Quantum Electronics, vol. 58, no. 3, pp. 1-5, June 2022, Art no. 4000205 ...[Visit Journal] We report high quality, low dark current, deep Ultraviolet AlGaN/AlN Photodetectors on AlN substrate. AlGaN based Photodetectors are grown and fabricated both on AlN and Sapphire substrates with the same epilayer structure. Subsequently, electrical characteristics of both photodetectors on AlN substrate and Sapphire are compared. A reduction of 4 orders of magnitude of dark current density is reported in UV detectors grown on AlN substrate with respect to Sapphire substrate. [reprint (PDF)]

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