Center for Quantum Devices - Most Downloaded Journal Articles

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17.	Highly temperature insensitive quantum cascade lasers Y. Bai, N. Bandyopadhyay, S. Tsao, E. Selcuk, S. Slivken and M. Razeghi Applied Physics Letters, Vol. 97, No. 25-- December 20, 2010 ...[Visit Journal] An InP based quantum cascade laser (QCL) heterostructure emitting around 5 μm is grown with gas-source molecular beam epitaxy. The QCL core design takes a shallow-well approach to maximize the characteristic temperatures, T(0) and T(1), for operations above room temperature. A T(0) value of 383 K and a T(1) value of 645 K are obtained within a temperature range of 298–373 K. In room temperature continuous wave operation, this design gives a single facet output power of 3 W and a wall plug efficiency of 16% from a device with a cavity length of 5 mm and a ridge width of 8 μm. [reprint (PDF)]
17.	Type-II superlattice dual-band LWIR imager with M-barrier and Fabry-Perot resonance E.K. Huang, A. Haddadi, G. Chen, B.M. Nguyen, M.A. Hoang, R. McClintock, M. Stegall, and M. Razeghi OSA Optics Letters, Vol. 36, No. 13, p. 2560-2562-- July 1, 2011 ...[Visit Journal] We report a high performance long-wavelength IR dual-band imager based on type-II superlattices with 100% cutoff wavelengths at 9.5 μm (blue channel) and 13 μm (red channel). Test pixels reveal background-limited behavior with specific detectivities as high as ∼5×10¹¹ Jones at 7.9 μm in the blue channel and ∼1×10¹¹ Jones at 10.2 μm in the red channel at 77 K. These performances were attributed to low dark currents thanks to the M-barrier and Fabry–Perot enhanced quantum efficiencies despite using thin 2 μm absorbing regions. In the imager, the high signal-to-noise ratio contributed to median noise equivalent temperature differences of ∼20 mK for both channels with integration times on the order of 0.5 ms, making it suitable for high speed applications. [reprint (PDF)]
17.	Schottky barrier heights and conduction-band offsets of In_1-xGa_xAs_1-yP_y lattice matched to GaAs J.K. Lee, Y.H. Cho, B.D. Choe, K.S. Kim, H.I. Jeon, H. Lim and M. Razeghi Applied Physics Letters 71 (7)-- August 18, 1997 ...[Visit Journal] The Schottky barrier heights of Au/In_1−xGa_xAs_1−yP_y contacts have been determined as a function of y by the capacitance–voltage and temperature dependent current–voltage characteristics measurements. The barrier height is observed to increase as y is increased for both n- and p-type materials, with a more rapid increase for the p-type material. The compositional variation of the barrier heights for Au/n-In_1−xGa_xAs_1−yP_y is found to be identical to that of the conduction-band offsets in In_1−xGa_xAs_1−yP_y/GaAs heterojunctions. A possible cause of this phenomenon is also discussed. [reprint (PDF)]
17.	Room temperature compact THz sources based on quantum cascade laser technology M. Razeghi; Q.Y. Lu; N. Bandyopadhyay; S. Slivken; Y. Bai Proc. SPIE 8846, Terahertz Emitters, Receivers, and Applications IV, 884602 (September 24, 2013)-- November 24, 2013 ...[Visit Journal] We present the high performance THz sources based on intracavity difference-frequency generation from mid-infrared quantum cascade lasers. Room temperature single-mode operation in a wide THz spectral range of 1-4.6 THz is demonstrated from our Čerenkov phase-matched THz sources with dual-period DFB gratings. High THz power up to 215 μW at 3.5 THz is demonstrated via epi-down mounting of our THz device. The rapid development renders this type of THz sources promising local oscillators for many astronomical and medical applications. [reprint (PDF)]
17.	Al_xGa_1-xN (0 ≤ x ≤ 1) Ultraviolet Photodetectors Grown on Sapphire by Metal-organic Chemical-vapor Deposition D. Walker, X. Zhang, A. Saxler, P. Kung, J. Xu, and M. Razeghi Applied Physics Letters 70 (8)-- February 24, 1997 ...[Visit Journal] Al_xGa_1–xN (0 ≤ x ≤ 1) ultraviolet photoconductors with cutoff wavelengths from 365 to 200 nm have been fabricated and characterized. The maximum detectivity reached 5.5 × 10⁸ cm·Hz^1/2/W at a modulating frequency of 14 Hz. The effective majority carrier lifetime in Al_xGa_1–xN materials, derived from frequency-dependent photoconductivity measurements, has been estimated to be from 6 to 35 ms. The frequency-dependent noise spectrum shows that it is dominated by Johnson noise at high frequencies for low-Al-composition samples. [reprint (PDF)]
17.	Type-II Antimonide-based Superlattices for the Third Generation Infrared Focal Plane Arrays Manijeh Razeghi, Edward Kwei-wei Huang, Binh-Minh Nguyen, Siamak Abdollahi Pour, and Pierre-Yves Delaunay SPIE Proceedings, Infrared Technology and Applications XXXVI, Vol. 7660, pp. 76601F-- May 10, 2010 ...[Visit Journal] In recent years, the Type-II superlattice (T2SL) material platform has seen incredible growth in the understanding of its material properties which has lead to unprecedented development in the arena of device design. Its versatility in band-structure engineering is perhaps one of the greatest hallmarks of the T2SL that other material platforms are lacking. In this paper, we discuss advantages of the T2SL, specifically the M-structure T2SL, which incorporates AlSb in the traditional InAs/GaSb superlattice. Using the M-structure, we present a new unipolar minority electron detector coined as the p-M-p, the letters which describe the composition of the device. Demonstration of this device structure with a 14 μm cutoff attained a detectivity of 4x10¹⁰ Jones (-50 mV) at 77 K. As device performance improves year after year with novel design contributions from the many researchers in this field, the natural progression in further enabling the ubiquitous use of this technology is to reduce cost and support the fabrication of large infrared imagers. In this paper, we also discuss the use of GaAs substrates as an enabling technology for third generation imaging on T2SLs. Despite the 7.8% lattice mismatch between the native GaSb and alternative GaAs substrates, T2SL photodiodes grown on GaAs at the MWIR and LWIR have been demonstrated at an operating temperature of 77 K [reprint (PDF)]
17.	Two‐dimensional electron gases in quantum well and superlattices of Ga0.25In0.75As0.50P0.50/InP heterostructures grown by low pressure metalorganic chemical vapor deposition M. Razeghi; J. P. Duchemin; J. C. Portal Appl. Phys. Lett. 46 (1): 46–48 (1985)-- January 1, 1985 ...[Visit Journal] We report the first observation of a two‐dimensional electron gas from Shubnikov–de Haas experiments, in a Ga0.25In0.75As0.50P0.50‐InP heterojunction, multi‐quantum well, and superlattices grown by metalorganic chemical vapor deposition at reduced pressure. [reprint (PDF)]
17.	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 ...[Visit Journal] 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 (PDF)]
17.	Comparison of type-II superlattice and HgCdTe infrared detector technologies Jagmohan Bajaj; Gerry Sullivan; Don Lee; Ed Aifer; Manijeh Razeghi Proc. SPIE 6542, Infrared Technology and Applications XXXIII, 65420B (May 14, 2007)-- May 14, 2007 ...[Visit Journal] Performance of HgCdTe detector technology surpasses all others in the mid-wave and long-wave infrared spectrum. This technology is relatively mature with current effort focused on improving uniformity, and demonstrating increased focal plane array (FPA) functionality. Type-II superlattice (InAs-GaSb and related alloys) detector technology has seen rapid progress over the past few years. The merits of the superlattice material system rest on predictions of even higher performance than HgCdTe and of engineering advantages. While no one has demonstrated Type-II superlattice detectors with performance superior to HgCdTe detectors, the difference in performance between these two technologies is decreasing. In this paper, we review the status and highlight relative merits of both HgCdTe and Type-II superlattice based detector technologies. [reprint (PDF)]
17.	Gain and recombination dynamics of quantum-dot infrared photodetecto H. Lim, B. Movaghar, S. Tsao, M. Taguchi, W. Zhang, A.A. Quivy, and M. Razeghi Virtual Journal of Nanoscale Science & Technology-- December 4, 2006 ...[Visit Journal][reprint (PDF)]
17.	High power photonic crystal distributed feedback quantum cascade lasers emitting at 4.5 micron B. Gokden, S. Slivken and M. Razeghi SPIE Proceedings, San Francisco, CA (January 22-28, 2010), Vol. 7608, p. 760806-1-- January 22, 2010 ...[Visit Journal] Quantum cascade lasers possess very small linewidth enhancement factor, which makes them very prominent candidates for realization of high power, nearly diffraction limited and single mode photonic crystal distributed feedback broad area lasers in the mid-infrared frequencies. In this paper, we present room temperature operation of a two dimensional photonic crystal distributed feedback quantum cascade laser emitting at 4.5 µm. peak power up to ~0.9 W per facet is obtained from a 2 mm long laser with 100 µm cavity width at room temperature. The observed spectrum is single mode with a very narrow linewidth. Far-field profile has nearly diffraction limited single lobe with full width at half maximum of 3.5 degree normal to the facet. The mode selection and power output relationships are experimentally established with respect to different cavity lengths for photonic crystal distributed feedback quantum cascade lasers. [reprint (PDF)]
17.	Novel Sb-based Alloys for Uncooled Infrared Photodetector Applications M. Razeghi SPIE Conference, San Jose, CA, -- January 22, 2001 ...[Visit Journal] We report on the growth and characterization of InSbBi, InTlSb, InTlP, and the quaternary alloys for uncooled long- wavelength infrared photodetector applications. The layers were grown on InSb and GaAs substrates by low-pressure metalorganic chemical vapor deposition. The incorporation of Bi and Tl in InSb was investigated with high-resolution x-ray diffraction, energy dispersive x-ray analysis, and optical photoresponse measurements. We also demonstrate the photodetectors fabricated from the grown InSbBi and InTlSb alloys. InSb_0.96Bi_0.04 photoconductive detectors exhibited a responsivity of 3.2 V/W at 77 K. The estimated Johnson noise limited detectivityat 7 micrometers was 1.7 X 10⁸ cm·Hz^½/W at 77 K. A room temperature operating InSb_0.95Bi_0.05 photodetector was also demonstrated.Photoresponse up to 12 micrometers was achieved at 300 K. The responsivity and Johnson noise-limited detectivity at 10.6 μm were 1.9 mV/W and 1.2 X 10⁶ cm·Hz^½/W, respectively. Photoresponse up to 15 μm was achieved at 300 K from quaternary InTlAsSb and InBiAsSb alloys. [reprint (PDF)]
17.	High-speed, low-noise metal-semiconductor-metal ultraviolet photodetectors based on GaN D. Walker, E. Monroy, P. Kung, J. Wu, M. Hamilton, F.J. Sanchez, J. Diaz, and M. Razeghi Applied Physics Letters 74 (5)-- February 1, 1999 ...[Visit Journal] We present the fabrication and characterization of nonintentionally doped GaN and GaN:Mg Schottky metal–semiconductor–metal (MSM) photodetectors, grown on sapphire by metalorganic chemical vapor deposition. Low-leakage, Schottky contacts were made with Pt/Au. The devices are visible blind, with an ultraviolet/green contrast of about five orders of magnitude. The response times of the MSM devices were <10 ns and about 200 ns for GaN and GaN:Mg, respectively. The noise power spectral density remains below the background level of the system (10−24 A²/Hz) up to 5 V, for the undoped GaN MSM detector. [reprint (PDF)]
17.	Growth of GaInAs‐InP multiquantum wells on garnet (GGG=Gd3Ga5O12) substrate by metalorganic chemical vapor deposition M. Razeghi; P‐L. Meunier; P. Maurel M. Razeghi, P‐L. Meunier, P. Maurel; Growth of GaInAs‐InP multiquantum wells on garnet (GGG=Gd3Ga5O12) substrate by metalorganic chemical vapor deposition. J. Appl. Phys. 15 March 1986; 59 (6): 2261–2263-- March 15, 1986 ...[Visit Journal] Ga0.47In0.53As‐InP multiquantum wells grown by low‐pressure metalorganic chemical vapor deposition on garnet (GGG=Gd3Ga5O12 with a=12.383 Å) substrates are presented for the first time. The x‐ray diffraction pattern shows that the orientation of the epitaxial layer is (111) while the underlying substrate orientation is (100). The photoluminescence at 77 K is due to the GaInAs layers. [reprint (PDF)]
17.	Solar-blind photodetectors based on Ga₂O₃ and III-nitrides Ryan McClintock; Alexandre Jaud; Lakshay Gautam; Manijeh Razeghi Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128803-- January 31, 2020 ...[Visit Journal] Recently, there has been a surge of interest in the wide bandgap semiconductors for solar blind photo detectors (SBPD). This work presents our recent progress in the growth/doping of AlGaN and Ga₂O₃ thin films for solar blind detection applications. Both of these thin films grown are grown by metal organic chemical vapor deposition (MOCVD) in the same Aixtron MOCVD system. Solar-blind metal-semiconductor-metal photodetectors were fabricated with Ga₂O₃. Spectral responsivity studies of the MSM photodetectors revealed a peak at 261 nm and a maximum EQE of 41.7% for a −2.5 V bias. We have also demonstrated AlGaN based solar-blind avalanche photodiodes with a gain in excess of 57,000 at ~100 volts of reverse bias. This gain can be attributed to avalanche multiplication of the photogenerated carriers within the device. Both of these devices show the potential of wide bandgap semiconductors for solar blind photo detectors. [reprint (PDF)]
17.	Structural and compositional characterization of MOVPE GaN thin films transferred from sapphire to glass substrates using chemical lift-off and room temperature direct wafer bonding and GaN wafer scale MOVPE growth on ZnO-buffered sapphire S. Gautier, T. Moudakir, G. Patriarche, D.J. Rogers, V.E. Sandana, F. Hosseini Teherani, P. Bove, Y. El Gmili, K. Pantzas, Suresh Sundaram, D. Troadec, P.L. Voss, M. Razeghi, A. Ougazzaden Journal of Crystal Growth, Volume 370, Pages 63-67 (2013)-- May 1, 2013 ...[Visit Journal] GaN thin films were grown on ZnO/c-Al₂O₃ with excellent uniformity over 2 in. diameter wafers using a low temperature/pressure MOVPE process with N₂ as a carrier and dimethylhydrazine as an N source. 5 mm×5 mm sections of similar GaN layers were direct-fusion-bonded onto soda lime glass substrates after chemical lift-off from the sapphire substrates. X-Ray Diffraction, Scanning Electron Microscopy and Transmission Electron Microscopy confirmed the bonding of crack-free wurtzite GaN films onto a glass substrate with a very good quality of interface, i.e. continuous/uniform adherence and absence of voids or particle inclusions. Using this approach, (In) GaN 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 the expensive sapphire substrate so it can be utilized again for growth. [reprint (PDF)]
17.	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)]
17.	Molecular Beam Epitaxial Growth of High Quality InSb E. Michel, G. Singh, S. Slivken, C. Besikci, P. Bove, I. Ferguson, and M. Razeghi Applied Physics Letters 65 (26)-- December 26, 1994 ...[Visit Journal] In this letter we report on the growth of high quality InSb by molecular beam epitaxy that has been optimized using reflection high energy electron diffraction. A 4.8 µm InSb layer grown on GaAs at a growth temperature of 395 °C and a III/V incorporation ratio of 1:1.2 had an x-ray rocking curve of 158 arcsec and a Hall mobility of 92,300 cm²·V⁻¹ at 77 K. This is the best material quality obtained for InSb nucleated directly onto GaAs reported to date. [reprint (PDF)]
17.	Monolithically, widely tunable quantum cascade lasers based on a heterogeneous active region design Wenjia Zhou, Neelanjan Bandyopadhyay, Donghai Wu, Ryan McClintock & Manijeh Razeghi Nature Scientific Reports 6, Article number: 25213 -- June 8, 2016 ...[Visit Journal] Quantum cascade lasers (QCLs) have become important laser sources for accessing the mid-infrared (mid-IR) spectral range, achieving watt-level continuous wave operation in a compact package at room temperature. However, up to now, wavelength tuning, which is desirable for most applications, has relied on external cavity feedback or exhibited a limited monolithic tuning range. Here we demonstrate a widely tunable QCL source over the 6.2 to 9.1 μm wavelength range with a single emitting aperture by integrating an eight-laser sampled grating distributed feedback laser array with an on-chip beam combiner. The laser gain medium is based on a five-core heterogeneous QCL wafer. A compact tunable laser system was built to drive the individual lasers within the array and produce any desired wavelength within the available spectral range. A rapid, broadband spectral measurement (520 cm⁻¹) of methane using the tunable laser source shows excellent agreement to a measurement made using a standard low-speed infrared spectrometer. This monolithic, widely tunable laser technology is compact, with no moving parts, and will open new opportunities for MIR spectroscopy and chemical sensing. [reprint (PDF)]
17.	Sensitive detection of CO and N₂O using a high power CW 4.61 μm dfb-QCL based QEPAS sensor Yufei Ma; Rafał Lewicki; Manijeh Razeghi; Xin Yu; Frank K. Tittel CLEO: Science and Innovations, CLEO_SI 2013. 2013:JW2A.80-- June 9, 2013 ...[Visit Journal] A high power CW DFB-QCL based CO and N₂O QEPAS sensor demonstrating the MDL of 1.5 ppbv and 23 ppbv, respectively was developed. Continuous monitoring of atmospheric CO and N2O concentration levels were performed. [reprint (PDF)]
17.	Very High Average Power at Room Temperature from λ ~ 5.9 μm Quantum Cascade Lasers J.S. Yu, S. Slivken, A. Evans, J. David and M. Razeghi Virtual Journal of Nanoscale Science & Technology 26-- May 26, 2003 ...[Visit Journal][reprint (PDF)]
17.	2.4 W room temperature continuous wave operation of distributed feedback quantum cascade lasers Q.Y. Lu, Y. Bai, N. Bandyopadhyay, S. Slivken and M. Razeghi Applied Physics Letters, Vol. 98, No. 18, p. 181106-1-- May 4, 2011 ...[Visit Journal] We demonstrate high power continuous-wave room-temperature operation surface-grating distributed feedback quantum cascade lasers at 4.8 μm. High power single mode operation benefits from a combination of high-reflection and antireflection coatings. Maximum single-facet continuous-wave output power of 2.4 W and peak wall plug efficiency of 10% from one facet is obtained at 298 K. Single mode operation with a side mode suppression ratio of 30 dB and single-lobed far field without beam steering is observed. [reprint (PDF)]
17.	Relaxation kinetics in quantum cascade laser S. Slivken, V. Litvinov, M. Razeghi, and J.R. Meyer Journal of Applied Physics 85 (2)-- January 15, 1999 ...[Visit Journal] Relaxation kinetics in a quantum cascade intersubband laser are investigated. Distribution functions and gain spectra of a three-subband double-quantum-well active region are obtained as a function of temperature and injection current. The potentially important role of the nonequilibrium phonons at lasing threshold is shown and discussed in details. It is shown that the threshold current is strongly dependent of the power dissipated in the active region in steady state. The numerical calculations for an 8.5 μm laser illustrate the general issues of relaxation kinetics in quantum cascade lasers. Temperature dependence of the threshold current is obtained in a good agreement with the experiments. [reprint (PDF)]
17.	Minority electron unipolar photodetectors based on Type-II InAs/GaSb/AlSb superlattices for very long wavelength infrared detection B.M. Nguyen, S. Bogdanov, S. Abdollahi Pour, and M. Razeghi Applied Physics Letters, Vol. 95, No. 18, p. 183502-- November 2, 2009 ...[Visit Journal] We present a hybrid photodetector design that inherits the advantages of traditional photoconductive and photovoltaic devices. The structure consists of a barrier layer blocking the transport of majority holes in a p-type semiconductor, resulting in an electrical transport due to minority carriers with low current density. By using the M-structure superlattice as a barrier region, the band alignments can be experimentally controlled, allowing for the efficient extraction of the photosignal with less than 50 mV bias. At 77 K, a 14 µm cutoff detector exhibits a dark current 3.3 mA·cm⁻², a photoresponsivity of 1.4 A/W, and the associated shot noise detectivity of 4×10¹⁰ Jones. [reprint (PDF)]
17.	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 ...[Visit Journal] 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·Hz^½/W. [reprint (PDF)]

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