Center for Quantum Devices - Most Downloaded Journal Articles

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16.	Monolithic Integration of GaInAs/InP Quantum Well Infrared Photodetectors on Si Substrate M. Erdtmann and M. Razeghi SPIE Conference, San Jose, CA, -- January 22, 2001 ...[Visit Journal] Using low-pressure metalorganic chemical vapor deposition, we have grown GaInAs/InP QWIP structures on GaAs-coated Si substrate. First, the procedure to optimize the epitaxy of the InP buffer layer on Si substrate is given. Excellent crystallinity and a mirror-like surface morphology were obtained by using both a two-step growth process at the beginning of the InP buffer layer growth and several series of thermal cycle annealing throughout the InP buffer layer growth. Second, results of fabricated GaInAs/InP QWIPs on Si substrate are presented. At a temperature of 80 K, the peak response wavelength occurs at 7.4 μm. The responsivities of QWIPs on both Si and InP substrates with identical structures are equal up to biases of 1.5 V. At a bias of 3 V, the responsivity of the QWIPs on Si substrate is 1.0 A/W. [reprint (PDF)]
16.	Photoluminescence study of InAsSb/InAsSbP heterostructures grown by low-pressure metalorganic chemical vapor deposition S. Kim, M. Erdtmann, D. Wu, E. Kaas, H. Yi, J. Diaz, and M. Razeghi Applied Physics Letters 69 (11)-- September 9, 1996 ...[Visit Journal] Photoluminescence has been measured for double‐ and separate‐confinement InAsSb/InAsSbP heterostructures grown by low‐pressure metalorganic vapor deposition. A measurement of the integrated luminescence intensity at the temperature range of 77–300 K shows that over a wide range of excitation level (1–5×10² W/cm²) the radiative transitions are the dominant. mechanism below T∼170 K. Auger recombination coefficient C=C₀ exp(−E_a/kT) with C₀≊5×10⁻²⁷ cm⁶/s and E_a≊40 meV has been estimated. [reprint (PDF)]
16.	High-speed free-space optical communications based on quantum cascade lasers and type-II superlattice detectors Stephen M. Johnson; Emily Dial; M. Razeghi Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128814-- January 31, 2020 ...[Visit Journal] Free-space optical communications (FSOC) is a promising avenue for point-to-point, high-bandwidth, and high-security communication links. It has the potential to solve the “last mile” problem modern communication systems face, allowing for high-speed communication links without the expensive and expansive infrastructure required by fiber optic and wireless technologies 1 . Although commercial FSOC systems currently exist, due to their operation in the near infrared and short infrared ranges, they are necessarily limited by atmospheric absorption and scattering losses 2 . Mid-infrared (MWIR) wavelengths are desirable for free space communications systems because they have lower atmospheric scattering losses compared to near-infrared communication links. This leads to increased range and link uptimes. Since this portion of the EM spectrum is unlicensed, link establishment can be implemented quickly. Quantum cascade lasers (QCL) are ideal FSOC transmitters because their emission wavelength is adjustable to MWIR 3 . Compared to the typical VCSEL and laser diodes used in commercial NIR and SWIR FSOC systems, however, they require increased threshold and modulation currents 4 . Receivers based on type-II superlattice (T2SL) detectors are desired in FSOC for their low dark current, high temperature operation, and band gap tunable to MWIR 5. In this paper, we demonstrate the implementation of a high-speed FSOC system using a QCL and a T2SL detector. [reprint (PDF)]
16.	Quantum cascade lasers: from tool to product M. Razeghi, Q. Y. Lu, N. Bandyopadhyay, W. Zhou, D. Heydari, Y. Bai, and S. Slivken Optics Express Vol. 23, Issue 7, pp. 8462-8475-- March 25, 2015 ...[Visit Journal] The quantum cascade laser (QCL) is an important laser source in the mid-infrared and terahertz frequency range. The past twenty years have witnessed its tremendous development in power, wall plug efficiency, frequency coverage and tunability, beam quality, as well as various applications based on QCL technology. Nowadays, QCLs can deliver high continuous wave power output up to 5.1 W at room temperature, and cover a wide frequency range from 3 to 300 μm by simply varying the material components. Broadband heterogeneous QCLs with a broad spectral range from 3 to 12 μm, wavelength agile QCLs based on monolithic sampled grating design, and on-chip beam QCL combiner are being developed for the next generation tunable mid-infrared source for spectroscopy and sensing. Terahertz sources based on nonlinear generation in QCLs further extend the accessible wavelength into the terahertz range. Room temperature continuous wave operation, high terahertz power up to 1.9 mW, and wide frequency tunability form 1 to 5 THz makes this type of device suitable for many applications in terahertz spectroscopy, imaging, and communication. [reprint (PDF)]
16.	Quantum oscillations at a Ga0.47In0.53AsInP heterojunction interface R.J Nicholas a, M.A Brummell a , J.C Portal b, M Razeghi c, M.A Poisson R.J Nicholas, M.A Brummell, J.C Portal, M Razeghi, M.A Poisson, Quantum oscillations at a Ga0.47In0.53AsInP heterojunction interface, Solid State Communications, Volume 43, Issue 11, 1982, Pages 825-828,-- September 1, 1982 ...[Visit Journal] We report the observation of a two dimensional gas of high mobility electrons at the interface of a Ga0.47In0.53AsInP heterojunction grown by MOCVD. The two dimensional electron concentrations and effective mass are determined by Shubnikov-de Haas studies, and compared with theoretical predictions. Evidence of an enhancement of the g-factor is observed. We also report observations of very pronounced quantum Hall steps as seen in GaAs-GaAlAs heterojunctions. [reprint (PDF)]
16.	Surface leakage reduction in narrow band gap type-II antimonide-based superlattice photodiodes E.K. Huang, D. Hoffman, B.M. Nguyen, P.Y. Delaunay and M. Razeghi Applied Physics Letters, Vol. 94, No. 5, p. 053506-1-- February 2, 2009 ...[Visit Journal] Inductively coupled plasma (ICP) dry etching rendered structural and electrical enhancements on type-II antimonide-based superlattices compared to those delineated by electron cyclotron resonance (ECR) with a regenerative chemical wet etch. The surface resistivity of 4×10⁵ Ω·cm is evidence of the surface quality achieved with ICP etching and polyimide passivation. By only modifying the etching technique in the fabrication steps, the ICP-etched devices with a 9.3 µm cutoff wavelength revealed a diffusion-limited dark current density of 4.1×10⁻⁶ A/cm² and a maximum differential resistance at zero bias in excess of 5300 Ω·cm² at 77 K, which are an order of magnitude better in comparison to the ECR-etched devices. [reprint (PDF)]
16.	Review of high power frequency comb sources based on InP From MIR to THZ at CQD Manijeh Razeghi, Quanyong Lu, Donghai Wu, Steven Slivken Event: SPIE Optical Engineering + Applications, 2018, San Diego, California, United States-- September 14, 2018 ...[Visit Journal] We present the recent development of high performance compact frequency comb sources based on mid-infrared quantum cascade lasers. Significant performance improvements of our frequency combs with respect to the continuous wave power output, spectral bandwidth, and beatnote linewidth are achieved by systematic optimization of the device's active region, group velocity dispersion, and waveguide design. To date, we have demonstrated the most efficient, high power frequency comb operation from a free-running room temperature continuous wave (RT CW) dispersion engineered QCL at λ~5-9 μm. In terms of bandwidth, the comb covered a broad spectral range of 120 cm⁻¹ with a radio-frequency intermode beatnote spectral linewidth of 40 Hz and a total power output of 880 mW at 8 μm and 1 W at ~5.0 μm. The developing characteristics show the potential for fast detection of various gas molecules. Furthermore, THz comb sources based on difference frequency generation in a mid-IR QCL combs could be potentially developed. [reprint (PDF)]
16.	High-power continuous-wave operation of distributed-feedback quantum-cascade lasers at λ ~ 7.8 µm S.R. Darvish, W. Zhang, A. Evans, J.S. Yu, S. Slivken, and M. Razeghi Applied Physics Letters, 89 (25)-- December 18, 2006 ...[Visit Journal] The authors present high-power continuous-wave (cw) operation of distributed-feedback quantum-cascade lasers. Continuous-wave output powers of 56 mW at 25 °C and 15 mW at 40 °C are obtained. Single-mode emission near 7.8 μm with a side-mode suppression ratio of >=30 dB and a tuning range of 2.83 cm⁻¹ was obtained between 15 and 40 °C. The device exhibits no beam steering with a full width at half maximum of 27.4° at 25 °C in cw mode. [reprint (PDF)]
16.	Reliable GaN-based resonant tunneling diodes with reproducible room-temperature negative differential resistance C. Bayram, D.K. Sadana, Z. Vashaei and M. Razeghi SPIE Proceedings, Vol. 8268, p. 826827-- January 22, 2012 ...[Visit Journal] negative differential resistance (NDR). Compared to other negative resistance devices such as (Esaki) tunnel and transferred-electron devices, RTDs operate much faster and at higher temperatures. III-nitride materials, composed of AlGaInN alloys, have wide bandgap, high carrier mobility and thermal stability; making them ideal for high power high frequency RTDs. Moreover, larger conduction band discontinuity promise higher NDR than other materials (such as GaAs) and room-temperature operation. However, earlier efforts on GaN-based RTD structures have failed to achieve a reliable and reproducible NDR. Recently, we have demonstrated for the first time that minimizing dislocation density and eliminating the piezoelectric fields enable reliable and reproducible NDR in GaN-based RTDs even at room temperature. Observation of NDR under both forward and reverse bias as well as at room and low temperatures attribute the NDR behaviour to quantum tunneling. This demonstration marks an important milestone in exploring III-nitride quantum devices, and will pave the way towards fundamental quantum transport studies as well as for high frequency optoelectronic devices such as terahertz emitters based on oscillators and cascading structures. [reprint (PDF)]
16.	High-Performance Type-II InAs/GaSb Superlattice Photodiodes with Cutoff Wavelength Around 7 µm Y. Wei, A. Hood, H. Yau, V. Yazdanpanah, M. Razeghi, M.Z. Tidrow and V. Nathan Applied Physics Letters, 86 (9)-- February 28, 2005 ...[Visit Journal] We report the most recent result in the area of type-II InAs/GaSb superlattice photodiodes that have a cutoff wavelength around 7 µm at 77 K. Superlattice with a period of 40 Å lattice matched to GaSb was realized using Ga_xIn_1–x type interface engineering technique. Compared with significantly longer period superlattices, we have reduced the dark current density under reverse bias dramatically. For a 3 µm thick structure, using sulfide-based passivation, the dark current density reached 2.6×10^–5 A/cm² at –3 V reverse bias at 77 K. At this temperature the photodiodes have R₀A of 9300 Ω·cm² and a thermally limited zero bias detectivity of 1×10¹² cm·Hz^½/W. The 90%–10% cutoff energy width was only 16.5 meV. The devices did not show significant dark current change at 77 K after three months storage in the atmosphere. [reprint (PDF)]
16.	Improved performance of quantum cascade lasers via manufacturable quality epitaxial side down mounting process utilizing aluminum nitride heatsinks A. Tsekoun, R. Go, M. Pushkarsky, M. Razeghi, C.K.N. Patel SPIE Conference, San Jose, CA, Vol. 6127, pp. 612702-- January 23, 2006 ...[Visit Journal] We report substantially improved performance of high power quantum cascade lasers by utilizing epi-side down mounting that provides superior heat dissipation properties. We have obtained CW power output of 450 mW at 20°C from mid-IR QCLs. The improved thermal management achieved with epi-side down mounting has also permitted us to carry out initial lifetime tests on the mid-IR QCLs. No degradation of power output is seen even after over 300 hours of CW operation at 25°C with power output in excess of 300 mW. We believe these improvements should permit incorporation of mid-IR QCLs in reliable instrumentation. [reprint (PDF)]
16.	Characterization of ZnO thin films grown on c-sapphire by pulsed laser deposition as templates for regrowth of zno by metal organic chemical vapor deposition D. J. Rogers ; F. Hosseini Teherani ; C. Sartel ; V. Sallet ; F. Jomard ; P. Galtier ; M. Razeghi Proc. SPIE 7217, Zinc Oxide Materials and Devices IV, 72170F (February 17, 2009)-- February 17, 2009 ...[Visit Journal] The use of ZnO template layers grown Pulsed Laser Deposition (PLD) has been seen to produce dramatic improvements in the surface morphology, crystallographic quality and optical properties of ZnO layers grown on c-sapphire substrates by Metal Organic Chemical Vapor Deposition. This paper provides complementary details on the PLD-grown ZnO template properties. [reprint (PDF)]
16.	Temperature dependent characteristics of λ ~ 3.8 µm room-temperature continuous-wave quantum-cascade lasers J.S. Yu, A. Evans, S. Slivken, S.R. Darvish and M. Razeghi Applied Physics Letters, 88 (25)-- June 19, 2006 ...[Visit Journal] The highest-performance device displays pulsed laser action at wavelengths between 3.4 and 3.6 μm, for temperatures up to 300 K, with a low temperature (80 K) threshold current density of approximately 2.6 kA/cm², and a characteristic temperature of T₀~130 K. The shortest wavelength QCL (λ ~ 3.05 μm) has a higher threshold current density (~12 kA/cm² at T=20 K) and operates in pulsed mode at temperatures up to 110 K. [reprint (PDF)]
16.	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 ...[Visit Journal] 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 (PDF)]
16.	Effects of well width and growth temperature on optical and structural characteristics of AlN/GaN superlattices grown by metal-organic chemical vapor deposition C. Bayram, N. Pere-Laperne, and M. Razeghi Applied Physics Letters, Vol. 95, No. 20, p. 201906-1-- November 16, 2009 ...[Visit Journal] AlN/GaN superlattices (SLs) employing various well widths (from 1.5 to 7.0 nm) are grown by metal-organic chemical vapor deposition technique at various growth temperatures (Ts) (from 900 to 1035 °C). The photoluminescence (PL), x-ray diffraction, and intersubband (ISB) absorption characteristics of these SLs and their dependency on well width and growth temperature are investigated. Superlattices with thinner wells (grown at the same Ts) or grown at lower Ts (employing the same well width) are shown to demonstrate higher strain effects leading to a higher PL energy and ISB absorption energy. Simulations are employed to explain the experimental observations. ISB absorptions from 1.04 to 2.15 µm are demonstrated via controlling well width and growth temperature. [reprint (PDF)]
16.	Emerging materials for photonics Miriam S. Vitiello, and Manijeh Razeghi APL Materials 5, 03510-- March 31, 2017 ...[Visit Journal] Photonics plays a major role in all aspects of human life. It revolutionized science by addressing fundamental scientiﬁc questions and by enabling key functions in many interdisciplinary ﬁelds spanning from quantum technologies to information andcommunicationscience,andfrombiomedicalresearchtoindustrialprocessmonitoring and life entertainment. [reprint (PDF)]
16.	Capacitance-voltage investigation of high purity InAs/GaSb superlattice photodiodes A. Hood, D. Hoffman, Y. Wei, F. Fuchs, and M. Razeghi Applied Physics Letters 88 (6)-- February 6, 2006 ...[Visit Journal] The residual carrier backgrounds of binary type-II InAs/GaSb superlattice photodiodes with cutoff wavelengths around 5 μm have been studied in the temperature range between 20 and 200 K. By applying a capacitance-voltage measurement technique, a residual background concentration below 10¹⁵ cm^–3 has been found. [reprint (PDF)]
16.	High Power 0.98 μm GaInAs/GaAs/GaInP Multiple Quantum Well Laser K. Mobarhan, M. Razeghi, G. Marquebielle and E. Vassilaki Journal of Applied Physics 72 (9)-- November 1, 1992 ...[Visit Journal] We report the fabrication of high quality Ga_0.8In_0.2As/GaAs/Ga_0.51In_0.49P multiple quantum well laser emitting at 0.98 μm grown by low pressure metalorganic chemical vapor deposition. Continuous wave operation with output power of 500 mW per facet was achieved at room temperature for a broad area laser with 130 μm width and 300 μm cavity length. This is an unusually high value of output power for this wavelength laser in this material system. The differential quantum efficiency exceeded 75% with excellent homogeneity and uniformity. The characteristic temperature, T₀ was in the range of 120–130 K. [reprint (PDF)]
16.	Investigation of the Heteroepitaxial Interfaces in the GaInP/GaAs Superlattices by High Resolution X-Ray Diffraction and Dynamical Solutions Xiaoguang He and Manijeh Razeghi Journal of Applied Physics 73 (7)-- April 1, 1993 ...[Visit Journal] Two GaAs/GaInP superlattices grown on GaAs substrates by low‐pressure metalorganic chemical vapor deposition have been studied using high resolution x‐ray diffraction measurements and simulations by solving Tagaki–Taupin equations. The strained layers at both interfaces of the GaAs well are identified from the simulations of the measured diffraction patterns. The purging of indium at the interface of GaInP/GaAs accounts for the strained layer at the GaInP/GaAs interface while the pressure difference in the gas lines, which results in the different traveling time to the sample surface, is attributed to the indium‐poor strained layer at the GaAs/GaInP interface. It is shown that high‐resolution x‐ray diffraction measurements combined with a dynamical simulation, are sensitive tools to study the heteroepitaxial interfaces on an atomic layer scale. In addition, the influence of a miscut of the substrate on the measurement is discussed in the article. It is shown that even though the miscut is small, the diffraction geometry is already an asymmetric one. More than 10% error in the superlattice period for a 2° miscut substrate can result when the miscut substrate is considered a symmetric geometry. [reprint (PDF)]
16.	Temperature dependence of the dark current and activation energy at avalanche onset of GaN Avalanche Photodiodes M.P. Ulmer, E. Cicek, R. McClintock, Z. Vashaei and M. Razeghi SPIE Proceedings, Vol. 8460, p. 84601G-1-- August 15, 2012 ...[Visit Journal] We report a study of the performance of an avalanche photodiode (APD) as a function of temperature from 564 K to 74 K. The dark current at avalanche onset decreases from 564 K to 74 K by approximately a factor of 125 and from 300 K to 74K the dark current at avalanche offset is reduced by a factor of about 10. The drop would have been considerably larger if the activation energy at avalanche onset (Ea) did not also decrease with decreasing temperature. These data give us insights into how to improve the single-photon counting performance of a GaN based ADP. [reprint (PDF)]
16.	Quantum Hall effect in In0.53Ga0.47As-InP heterojunctions with two populated electric subbands Y. Guldner, J. P. Vieren, and M. Voos F. Delahaye and D. Dominguez J. P. Hirtz and M. Razeghi Phys. Rev. B 33, 3990 1986-- March 15, 1986 ...[Visit Journal] Quantum-Hall-effect and Shubnikov–de Haas measurements are presented for InxGa1−xAs?(hyInP heterojunctions with two populated electric subbands and low electron density (𝑛𝑠≤5×1011 cm−2). The Shubnikov–de Haas oscillations clearly show two different periodicities. An anomalous behavior of the quantum Hall effect is observed, in particular some plateaus are missing and other plateaus are enhanced. Precise measurements of the Hall resistance have been performed and it is shown that the resistance of the i=2 plateau is equal to its theoretical value h/2𝑒2 with an uncertainty of ∼10−8. [reprint (PDF)]
16.	Investigations of ZnO thin films grown on c-Al(2)O(3) by pulsed laser deposition in N(2) + O(2) ambient D.J. Rogers, D.C. Look, F.H. Teherani, K. Minder, M. Razeghi, A. Largeteau, G. Demazeau, J. Morrod, K.A. Prior, A. Lusson, and S. Hassani Physica Status Solidi (c), Vol. 5, No. 9, p. 3084-3087-- July 1, 2008 ...[Visit Journal] ZnO films were deposited on c-Al₂O₃ using pulsed laser deposition both with and without N₂ in the growth ambient. X-ray diffraction revealed poorer crystal quality and surface morphology for one-step growths with N₂ in the ambient. A marked improvement in both the crystallographic and surface quality was obtained through use of two-step growths employing nominally undoped ZnO buffer layers prior to growth with N₂ in the ambient. All films showed majority n-type conduction in Hall measurements. Post-annealing for 30 minutes at 600 ºC in O₂ systematically reduced both the carrier concentration and the conductivity. A base room temperature carrier concentration of ~ 10¹⁶ cm^-3 was linked to Al diffusing from the substrate. 4.2 K photoluminescence spectra exhibited blue bands associated with the growths having N₂ in the ambient. Temperature dependent Hall measurements were consistent with N being incorporated in the films. Processed devices did not, however, show rectifying behavior or electroluminescence. [reprint (PDF)]
16.	Type-II InAs/GaSb Superlattice Focal Plane Arrays for High-Performance Third Generation Infrared Imaging and Free-Space Communication M. Razeghi, A. Hood and A. Evans SPIE Conference, January 25-29, 2007, San Jose, CA Proceedings – Optoelectronic Integrated Circuits IX, Vol. 6476, p. 64760Q-1-9-- January 29, 2007 ...[Visit Journal] Free-space optical communications has recently been touted as a solution to the "last mile" bottleneck of high speed data networks providing highly secure, short to long range, and high bandwidth connections. However, commercial near infrared systems experience atmospheric scattering losses and scintillation effects which can adversely affect a link's uptime. By moving the operating wavelength into the mid or long wavelength infrared enhanced link uptimes and increased range can be achieved due to less susceptibility atmospheric affects. The combination of room temperature, continuous wave' high power quantum cascade lasers and high operating temperature Type-II superlattice photodetectors offers the benefits of mid and long wavelength infrared systems as well as practical operating conditions. [reprint (PDF)]
16.	Photoluminescence Study of AlGaN-based 280 nm Ultraviolet Light-Emitting Diodes A. Yasan, R. McClintock, K. Mayes, D.H. Kim, P. Kung, and M. Razeghi Applied Physics Letters, 83 (20)-- November 17, 2003 ...[Visit Journal] We investigated optical properties of single quantum well AlGaN-based UV 280 nm light-emitting diodes using temperature-dependent photoluminescence (PL) measurement. We found an "S-shaped" temperature dependence of the peak energy. From the Arrhenius plot of integrated PL intensity, we speculate that dislocations as well as thermal emission of carriers out of the quantum well are responsible for the PL quenching behavior. Also a second nonradiative channel with much lower activation energy was found, the origin of which we believe to be quenching of the bound excitons [reprint (PDF)]
16.	Electroluminescence at 375 nm from a Zn0/GaN:Mg/c-Al₂O₃ heterojunction light emitting diodes D.J. Rogers, F.Hosseini Teherani, A. Yasan, K. Minder, P. Kung, and M. Razeghi Applied Physics Letters, 88 (14)-- April 13, 2006 ...[Visit Journal] n-ZnO/p-GaN:Mg heterojunction light emitting diode (LED) mesas were fabricated on c-Al₂O₃ substrates using pulsed laser deposition for the ZnO and metal organic chemical vapor deposition for the GaN:Mg. Room temperature (RT) photoluminescence (PL) showed an intense main peak at 375 nm and a negligibly low green emission indicative of a near band edge excitonic emission from a ZnO layer with low dislocation/defect density. The LEDs showed I-V characteristics confirming a rectifying diode behavior and a RT electroluminescence (EL) peaked at about 375 nm. [reprint (PDF)]

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