Center for Quantum Devices - Most Downloaded Journal Articles

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16.	Development of high power, InP-based quantum cascade lasers on alternative epitaxial platforms Steven Slivken, Nirajman Shrestha, Manijeh Razeghi Proc. of SPIE Vol. 12895, Quantum Sensing and Nano Electronics and Photonics XX, 1289503 (28 January - 1 February 2024, San Francisco) doi: 10.1117/12.3009335 ...[Visit Journal] In this talk, challenges and solutions associated with the monolithic, epitaxial integration of mid- and longwave- infrared, InP-based quantum cascade lasers on GaAs and Si wafers will be discussed. Initial results, including room temperature, high power, and continuous wave operation, will be described. [reprint (PDF)]
16.	Recent Advances in InAs/GaSb Superlattices for Very Long Wavelength Infrared Detection G.J. Brown, F. Szmulowicz, K. Mahalingam, S. Houston, Y. Wei, A. Gin and M. Razeghi SPIE Conference, San Jose, CA, Vol. 4999, pp. 457-- January 27, 2003 ...[Visit Journal] New infrared (IR) detector materials with high sensitivity, multi-spectral capability, improved uniformity and lower manufacturing costs are required for numerous long and very long wavelength infrared imaging applications. One materials system has shown great theoretical and, more recently, experimental promise for these applications: InAs/In_xGa_1-xSb type-II superlattices. In the past few years, excellent results have been obtained on photoconductive and photodiode samples designed for infrared detection beyond 15 microns. The infrared properties of various compositions and designs of these type-II superlattices have been studied. The infrared photoresponse spectra are combined with quantum mechanical modeling of predicted absorption spectra to provide insight into the underlying physics behind the quantum sensing in these materials. Results for superlattice photodiodes with cut-off wavelengths as long as 25 microns are presented. [reprint (PDF)]
16.	Low frequency noise in 1024 x 1024 long wavelength infrared focal plane array base on Type-II InAs/GaSb superlattice A. Haddadi, S.R. Darvish, G. Chen, A.M. Hoang, B.M. Nguyen and M. Razeghi SPIE Proceedings, Vol. 8268, p. 82680X-- January 22, 2012 ...[Visit Journal] Recently, the type-II InAs/GaSb superlattice (T2SL) material platform is considered as a potential alternative for HgCdTe technology in long wavelength infrared (LWIR) imaging. This is due to the incredible growth in the understanding of its material properties and improvement of device processing which leads to design and fabrication of better devices. In this paper, we report electrical low frequency noise measurement on a high performance type-II InAs/GaSb superlattice 1024×1024 LWIR focal plane array. [reprint (PDF)]
16.	Evaluating the size-dependent quantum efficiency loss in a SiO₂-Y₂O₃hybrid gated type-II InAs/GaSb long-infrared photodetector array G. Chen , A. M. Hoang , and M. Razeghi Applied Physics Letters 104 , 103509 (2014)-- March 14, 2014 ...[Visit Journal] Growing Y₂O₃ on 20 nm SiO₂ to passivate a 11 μm 50% cut-off wavelength long-wavelength infrared type-II superlattice gated photodetector array reduces its saturated gate bias (VG_sat ) to −7 V. Size-dependent quantum efficiency (QE) losses are evaluated from 400 μm to 57 μm size gated photodiode. Evolution of QE of the 57 μm gated photodiode with gate bias and diode operation bias reveals different surface recombination mechanisms. At 77 K and VG,sat , the 57 μm gated photodiode exhibits QE enhancement from 53% to 63%, and it has 1.2 × 10⁻⁵ A/cm² dark current density at −200 mV, and a specific detectivity of 2.3 × 10¹² Jones. [reprint (PDF)]
16.	High-performance bias-selectable dual-band Short-/Mid-wavelength infrared photodetectors and focal plane arrays based on InAs/GaSb/AlSb Type-II superlattices M. Razeghi; A.M. Hoang; A. Haddadi; G. Chen; S. Ramezani-Darvish; P. Bijjam; P. Wijewarnasuriy; E. Decuir Proc. SPIE 8704, Infrared Technology and Applications XXXIX, 87041W (June 18, 2013)-- June 18, 2013 ...[Visit Journal] We report a bias selectable dual-band Type-II superlattice-based short-wave infrared (SWIR) and mid-wave infrared (MWIR) co-located photodetector capable of active and passive imaging. A new double-layer etch-stop scheme is introduced for back-side-illuminated photodetectors, which enhanced the external quantum efficiency both in the SWIR and MWIR spectral regions. Temperature-dependent dark current measurements of pixel-sized 27 μm detectors found the dark current density to be ∼1×10-5 A/cm2 for the ∼4.2 μm cut-off MWIR channel at 140 K. This corresponded to a reasonable imager noise equivalent difference in temperature of ∼49 mK using F/2.3 optics and a 10 ms integration time (tint), which lowered to ∼13 mK at 110 K using and integration time of 30 ms, illustrating the potential for high-temperature operation. The SWIR channel was found to be limited by readout noise below 150 K. An excellent imagery from the dual-band imager exemplifying pixel coincidence is shown. [reprint (PDF)]
16.	Uncooled operation of Type-II InAs/GaSb superlattice photodiodes in the mid- wavelength infrared range Y. Wei, A. Hood, H. Yau, A. Gin, M. Razeghi, M.Z. Tidrow, V. Natha Applied Physics Letters, 86 (23)-- June 6, 2005 ...[Visit Journal] We report high performance uncooled midwavelength infrared photodiodes based on interface-engineered InAs/GaSb superlattice. Two distinct superlattices were designed with a cutoff wavelength around 5 µm for room temperature and 77 K. The device quantum efficiency reached more than 25% with responsivity around 1 A/W. Detectivity was measured around 10⁹ cm·Hz^½/W at room temperature and 1.5×10¹³ cm·Hz^½/W at 77 K under zero bias. The devices were without antireflective coating. The device quantum efficiency stays at nearly the same level within this temperature range. Additionally, Wannier–Stark oscillations in the Zener tunneling current were observed up to room temperature. [reprint (PDF)]
16.	Optical and crystallographic properties and impurity incorporation of GaxIn1−xAs grown by liquid phase epitaxy, vapor phase epitaxy, and metal organic chemical vapor deposition K.‐H. Goetz; D. Bimberg; H. Jürgensen; J. Selders; A. V. Solomonov; G. F. Glinskii; M. Razeghi J. Appl. Phys. 54 (8): 4543–4552 (1983)-- March 29, 1983 ...[Visit Journal] Optical, crystallographic, and transport properties of nominally undoped n‐type and Zn doped p‐type Gax In1−xAs /InP (0.44 [reprint (PDF)]
16.	Broad area photonic crystal distributed feedback quantum cascade lasers emitting 34 W at λ ~ 4.36 μm B. Gokden, Y. Bai, N. Bandyopadhyay, S. Slivken and M. Razeghi Applied Physics Letters, Vol. 97, No. 13, p. 131112-1-- September 27, 2010 ...[Visit Journal] We demonstrate room temperature, high power, single mode, and diffraction limited operation of a two dimensional photonic crystal distributed feedback quantum cascade laser emitting at 4.36 μm. Total peak power up to 34 W is observed from a 3 mm long laser with 400 μm cavity width at room temperature. Far-field profiles have M2 figure of merit as low as 2.5. This device represents a significant step toward realization of spatially and spectrally pure broad area high power quantum cascade lasers. [reprint (PDF)]
16.	Extended short wavelength infrared heterojunction phototransistors based on type II superlattices Arash Dehzangi , Ryan McClintock, Donghai Wu , Abbas Haddadi, Romain Chevallier , and Manijeh Razeghi Applied Physics Letters 114, 191109-- May 17, 2019 ...[Visit Journal] A two terminal extended short wavelength infrared heterojunction phototransistor based on type-II InAs/AlSb/GaSb on a GaSb substrate is designed, fabricated, and investigated. With the base thickness of 40 nm, the device exhibited a 100% cut-off wavelength of 2.3 λ at 300 K. The saturated peak responsivity value is 320.5 A/W at 300 K, under front-side illumination without any antireflection coating. A saturated optical gain of 245 at 300K was measured. At the same temperature, the device exhibited a collector dark current density (at unity optical gain) and a DC current gain of 7.8 X 10³ A/cm² and 1100, respectively. The device exhibited a saturated dark current shot noise limited specific detectivity of 4.9 X 10¹¹ cm·Hz^½/W at 300 K which remains constant over a broad range of wavelengths and applied biases. [reprint (PDF)]
16.	High Power Electrically Injected Mid-Infrared Interband Lasers Grown by LP-MOCVD B. Lane and M. Razeghi Journal of Crystal Growth 221 (1-4)-- December 1, 2000[reprint (PDF)]
16.	High-Power Continuous-Wave Operation of a 6 µm Quantum-Cascade Laser at Room Temperature J.S. Yu, S. Slivken, A. Evans, L. Doris, and M. Razeghi Applied Physics Letters, 83 (13)-- September 29, 2003 ...[Visit Journal] We report continuous-wave (cw) operation of quantum-cascade lasers (λ= 6 µm) using a thick electroplated Au top contact layer and epilayer-up bonding on a copper heat sink up to a temperature of 308 K (35 °C). The high cw optical output powers of 132 mW at 293 K and 21 mW at 308 K are achieved with threshold current densities of 2.29 and 2.91 kA/cm², respectively, for a high-reflectivity-coated 15 µm wide and 2 mm long laser. [reprint (PDF)]
16.	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)]
16.	Gain and recombination dynamics of quantum-dot infrared photodetectors H. Lim, B. Movaghar, S. Tsao, M. Taguchi, W. Zhang, A.A. Quivy, and M. Razeghi Physical Review B, 74 (20)-- November 15, 2006 ...[Visit Journal] In this paper we present a theory of diffusion and recombination in QDIPs which is an attempt to explain the recently reported values of gain in these devices. We allow the kinetics to encompass both the diffusion and capture rate limited regimes of carrier relaxation using rigorous random walk and diffusion methods. The photoconductive gains are calculated and compared with the experimental values obtained from InGaAs/InGaP/GaAs and InAs/InP QDIPs using the generation-recombination noise analysis. [reprint (PDF)]
16.	SOLID-STATE DEEP UV EMITTERS/DETECTORS: Zinc oxide moves further into the ultraviolet David J. Rogers; Philippe Bove; Eric V. Sandana; Ferechteh Hosseini Teherani; Ryan McClintock; Manijeh Razeghi Laser Focus World. 2013;49(10):33-36.-- October 10, 2013 ...[Visit Journal] Latest advancements in the alloying of zinc oxide (ZnO) with magnesium (Mg) can offer an alternative to (Al) GaN-based emitters/detectors in the deep UV with reduced lattice and efficiency issues. The emerging potential of ZnO for UV emitter and detector applications is the result of a long, concerted, and fruitful R&D effort that has led to more than 7000 publications in 2012. ZnO is considered to be a potentially superior material for use in LEDs and laser diodes due to its larger exciton binding energy, as compared with 21 meV for GaN. Wet etching is also possible for ZnO with nearly all dilute acids and alkalis, while GaN requires hydrofluoric (HF) acid or plasma etching. High-quality ZnO films can be grown more readily on mismatched substrates and bulk ZnO substrates have better availability than their GaN equivalents. [reprint (PDF)]
16.	High power continuous wave operation of single mode quantum cascade lasers up to 5 W spanning λ∼3.8-8.3 µm Quanyong Lu, Steven Slivken, Donghai Wu, and Manijeh Razeghi Optics Express Vol. 28, Issue 10, pp. 15181-15188-- May 4, 2020 ...[Visit Journal] In this work, we report high power continuous wave room-temperature operation single mode quantum cascade lasers in the mid-infrared spectral range from 3.8 to 8.3 µm. Single mode robustness and dynamic range are enhanced by optimizing the distributed feedback grating coupling design and the facet coatings. High power single mode operation is secured by circumventing the over-coupling issue and spatial hole burning effect. Maximum single-facet continuous-wave output power of 5.1 W and wall plug efficiency of 16.6% is achieved at room temperature. Single mode operation with a side mode suppression ratio of 30 dB and single-lobed far field with negligible beam steering is observed. The significantly increased power for single mode emission will boost the QCL applications in long-range free-space communication and remote sensing of hazardous chemicals. [reprint (PDF)]
16.	High-power λ ~ 9.5 µm quantum-cascade lasers operating above room temperature in continuous-wave mode J.S. Yu, S. Slivken, A. Evans, S.R. Darvish, J. Nguyen, and M. Razeghi Applied Physics Letters, 88 (9)-- February 27, 2006 ...[Visit Journal] We report high-power continuous-wave (cw) operation of λ~9.5 μm quantum-cascade lasers to a temperature of 318 K. A high-reflectivity-coated 19-μm-wide and 3-mm-long device exhibits cw output powers as high as 150 mW at 288 K and still 22 mW at 318 K. In cw operation at 298 K, a threshold current density of 1.57 kA/cm², a slope efficiency of 391 mW/A, and a maximum wall-plug efficiency of 0.71% are obtained. [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.	*A Crystallographic Model of (001) Aluminum Nitride Epitaxial Thin Film Growth on (001) Sapphire Substrate* C.J. Sun, P. Kung, A. Saxler, H. Ohsato, M. Razeghi, and K. Haritos Journal of Applied Physics 75 (8)-- April 15, 1994 ...[Visit Journal] A direct comparison of the physical properties of GaN thin films is made as a function of the choice of substrate orientations. Gallium nitride single crystals were grown on (0001) and (011-bar 2) sapphire substrates by metalorganic chemical vapor deposition. Better crystallinity with fine ridgelike facets is obtained on the (011-bar 2) sapphire. Also lower carrier concentration and higher mobilities indicate both lower nitrogen vacancies and less oxygen incorporation on the (011-bar 2) sapphire. The results of this study show better physical properties of GaN thin films achieved on (011-bar 2) sapphire. [reprint (PDF)]
16.	Materials characterization of n-ZnO/p-GaN:Mg/c-Al(2)O(3) UV LEDs grown by pulsed laser deposition and metal-organic chemical vapor deposition D. Rogers, F.H. Teherani, P. Kung, K. Minder, and M. Razeghi Superlattices and Microstructures-- April 1, 2007 ...[Visit Journal] n-ZnO/p-GaN:Mg hybrid heterojunctions grown on c-Al₂O₃ substrates showed 375 nm room temperature electroluminescence. It was suggested that the high materials and interface quality obtained using pulsed laser deposition for the n-ZnO growth and metal–organic chemical vapor deposition for the p-GaN:Mg were key factors enabling the injection of holes and the radiative near band edge recombination in the ZnO. In this paper we present the materials characterization of this structure using x-ray diffraction, scanning electron microscopy and atomic force microscopy. [reprint (PDF)]
16.	Nitrides push performance of UV photodiodes Can Bayram; Manijeh Razeghi Laser Focus World. 45(9), pp. 47-51 (2009)-- September 1, 2009 ...[Visit Journal] The nitrides are known to be useful for creating the UV single-photon detectors with efficiencies of 20%, with its considerable advantages that could further enable quantum computing and data encryption. Such detectors would be well suited for numerous applications in the defense, commercial, and scientific arenas, including covert space-to-space communications, early missile-threat detection, chemical and biological threat detection and spectroscopy. The use of SAM regions is a common approach to reducing multiplication noise and enhancing gain through impact-ionization engineering that could benefit from the higher ionization coefficient by offering lower noise performance and higher gain. The ADPs also enables the realization of single-photon detection by using Geiger-mode operation, which entails operating the ADPs well above the breakdown voltage and using pulse-quenching circuitry. [reprint (PDF)]
16.	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)]
16.	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)]
16.	Room temperature continuous wave operation of quantum cascade lasers with 12.5% wall plug efficiency Y. Bai, S. Slivken, S.R. Darvish, and M. Razeghi Applied Physics Letters, Vol. 93, No. 2, p. 021103-1-- July 14, 2008 ...[Visit Journal] An InP based quantum cascade laser heterostructure emitting at 4.6 µm was grown with gas-source molecular beam epitaxy. The wafer was processed into a conventional double-channel ridge waveguide geometry with ridge widths of 19.7 and 10.6 µm without semi-insulating InP regrowth. An uncoated, narrow ridge device with a 4.8 mm cavity length was epilayer down bonded to a diamond submount and exhibits 2.5 W maximum output power with a wall plug efficiency of 12.5% at room temperature in continuous wave operation. [reprint (PDF)]
16.	Development of Quantum Cascade Lasers for High Peak Output Power and Low Threshold Current Density S. Slivken and M. Razeghi Solid State Electronics 46-- January 1, 2002 ...[Visit Journal] Design and material optimization are used to both decrease the threshold current density and increase the output power for quantum cascade lasers. Waveguides are designed to try and minimize free-carrier and surface-plasmon absorption. Excellent material characterization is also presented, showing excellent control over layer thickness, interface quality, and doping level. Experiments are done to both optimize the injector doping level and to maximize the output power from a single aperture. At 300 K, a threshold current density as low as 1.8 kA/cm² is reported, along with peak powers of approximately 2.5 W. Strain-balanced lasers are also demonstrated at λnot, vert, similar5 μm, exhibiting threshold current densities<300 A/cm² at 80 K. These values represent the state-of-the-art for mid-infrared lasers with λ>4 μm [reprint (PDF)]
16.	Low-Threshold 7.3 μm Quantum Cascade Lasers Grown by Gas-Source Molecular Beam Epitaxy S. Slivken, A. Matlis, A. Rybaltowski, Z. Wu and M. Razeghi Applied Physics Letters 74 (19)-- May 19, 1999 ...[Visit Journal] We report low-threshold 7.3 μm superlattice-based quantum cascade lasers. The threshold current density is 3.4 kA/cm² at 300 K and 1.25 kA/cm² at 79 K in pulsed mode for narrow (∼20 μm), 2 mm-long laser diodes. The characteristic temperature (T₀) is 210 K. The slope efficiencies are 153 and 650 mW/A at 300 and 100 K, respectively. Power output is in excess of 100 mW at 300 K. Laser far-field intensity measurements give divergence angles of 64° and 29° in the growth direction and in the plane of the quantum wells, respectively. Far-field simulations show excellent agreement with the measured results. [reprint (PDF)]

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