Center for Quantum Devices - Most Downloaded Journal Articles

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15.	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)]
15.	Stranski-Krastanov growth of InGaN quantum dots emitting in green spectra C. Bayram and M. Razeghi Applied Physics A: Materials Science and Processing, Vol. 96, No. 2, p. 403-408-- August 1, 2009 ...[Visit Journal] Self-assembled InGaN quantum dots (QDs) were grown on GaN templates by metalorganic chemical vapor deposition. 2D–3D growth mode transition through Stranski–Krastanov mode was observed via atomic force microscopy. The critical thickness for In_0.67Ga_0.33N QDs was determined to be four monolayers. The effects of growth temperature, deposition thickness, and V/III ratio on QD formation were examined. The capping of InGaN QDs with GaN was analyzed. Optimized InGaN quantum dots emitted in green spectra at room temperature. [reprint (PDF)]
15.	Widely Tunable, Single-Mode, High-Power Quantum Cascade Lasers M. Razeghi, B. Gokden, S. Tsao, A. Haddadi, N. Bandyopadhyay, and S. Slivken SPIE Proceedings, Intergreated Photonics: Materials, Devices and Applications, SPIE Microtechnologies Symposium, Prague, Czech Republic, April 18-20, 2011, Vol. 8069, p. 806905-1-- May 31, 2011 ...[Visit Journal] We demonstrate widely tunable high power distributed feedback quantum cascade laser array chips that span 190 nm and 200 nm from 4.4 um to 4.59 um and 4.5 um to 4.7 um respectively. The lasers emit single mode with a very narrow linewidth and side mode suppression ratio of 25 dB. Under pulsed operation power outputs up to 1.85 W was obtained from arrays with 3 mm cavity length and up to 0.95 W from arrays with 2 mm cavity length at room temperature. Continuous wave operation was also observed from both chips with 2 mm and 3 mm long cavity arrays up to 150 mW. The cleaved size of the array chip with 3 mm long cavities was around 4 mm x 5 mm and does not require sensitive external optical components to achieve wide tunability. With their small size and high portability, monolithically integrated DFB QCL Arrays are prominent candidates of widely tunable, compact, efficient and high power sources of mid-infrared radiation for gas sensing. [reprint (PDF)]
15.	Background limited long wavelength infrared type-II InAs/GaSb superlattice photodiodes operating at 110 K B.M. Nguyen, D. Hoffman, E.K. Huang, P.Y. Delaunay, and M. Razeghi Applied Physics Letters, Vol. 93, No. 12, p. 123502-1-- September 22, 2008 ...[Visit Journal] The utilization of the P+-pi-M-N+ photodiode architecture in conjunction with a thick active region can significantly improve long wavelength infrared Type-II InAs/GaSb superlattice photodiodes. By studying the effect of the depletion region placement on the quantum efficiency in a thick structure, we achieved a topside illuminated quantum efficiency of 50% for an N-on-P diode at 8.0 µm at 77 K. Both the double heterostructure design and the application of polyimide passivation greatly reduce the surface leakage, giving an R₀A of 416 Ω·cm² for a 1% cutoff wavelength of 10.52 µm, a Shot–Johnson detectivity of 8.1×10¹¹ cm·Hz^½/W at 77 K, and a background limited operating temperature of 110 K with 300 K background. [reprint (PDF)]
15.	Widely tuned room temperature terahertz quantum cascade laser sources Q.Y. Lu, N. Bandyopadhyay, S. Slivken, Y. Bai and M. Razeghi SPIE Proceedings, Vol. 8631, p. 863108-1, Photonics West, San Francisco, CA-- February 3, 2013 ...[Visit Journal] Room temperature THz quantum cascade laser sources with a broad spectral coverage based on intracavity difference frequency generation are demonstrated. Two mid-infrared active cores in the longer mid-IR wavelength range (9-11 micron)based on the single-phonon resonance scheme are designed with a second-order difference frequency nonlinearity specially optimized for 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)]
15.	Surface Emitting, Tunable, Mid-Infrared Laser with High Output Power and Stable Output Beam Steven Slivken, Donghai Wu & Manijeh Razeghi Scientific Reports volume 9, Article number: 549-- January 24, 2019 ...[Visit Journal] A reflective outcoupler is demonstrated which can allow for stable surface emission from a quantum cascade laser and has potential for cost-effective wafer-scale manufacturing. This outcoupler is integrated with an amplified, electrically tunable laser architecture to demonstrate high power surface emission at a wavelength near 4.9 μm. Single mode peak power up to 6.7 W is demonstrated with >6 W available over a 90 cm⁻¹ (215 nm) spectral range. A high quality output beam is realized with a simple, single-layer, anti-reflective coating. The beam shape and profile are shown to be independent of wavelength. [reprint (PDF)]
15.	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 Applied Physics Letters, 82 (20)-- May 19, 2003 ...[Visit Journal] We report a very high average output power at room temperature for quantum-cascade lasers emitting at λ ~ 5.9 µm. For high-reflectivity-coated 2-mm-long cavities, a low threshold current density of 1.7 kA/cm² was obtained at room temperature. From 300 to 400 K, the characteristic temperature (T0) was 198 K. A maximum average output power of 0.67 W was achieved. In addition, 0.56 W average output power was observed at a duty cycle of 56%. [reprint (PDF)]
15.	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)]
15.	Self-assembled semiconductor quantum dot infrared photodetector operating at room temperature and focal plane array Ho-Chul Lim; Stanley Tsao; Wei Zhang; Manijen Razeghi Proc. SPIE 6542, Infrared Technology and Applications XXXIII, 65420R (May 14, 2007)-- May 14, 2007 ...[Visit Journal] Self-assembled semiconductor quantum dots have attracted much attention because of their novel properties and thus possible practical applications including the lasers, detectors and modulators. Especially the photodetectors which have quantum dots in their active region have been developed and show promising performances such as high operation temperature due to three dimensional confinement of the carriers and normal incidence in contrast to the case of quantum well detectors which require special optical coupling schemes. Here we report our recent results for mid-wavelength infrared quantum dot infrared photodetector grown by low-pressure metalorganic chemical vapor deposition. The material system we have investigated consists of 25 period self-assembled InAs quantum dot layers on InAlAs barriers, which are lattice-matched to InP substrates, covered with InGaAs quantum well layers and InAlAs barriers. This active region was sandwiched by highly doped InP contact layers. The device operates at 4.1 μm with a peak detectivity of 2.8×10¹¹ cm·Hz^1/2/W at 120 K and a quantum efficiency of 35 %. The photoresponse can be observed even at room temperature resulting in a peak detectivity of 6×10⁷ cm·Hz^1/2/W. A 320×256 focal plane array has been fabricated in this kind of device. Its performance will also be discussed here. [reprint (PDF)]
15.	Growth of In_1-xTl_xSb, a New Infrared Material, by Low-Pressure Metalorganic Chemical Vapor Deposition Y.H. Choi, R. Sudharsanan, C, Besikci, and M. Razeghi Applied Physics Letters 63 (3)-- July 19, 1993 ...[Visit Journal] We report the growth of In_1-xTl_xSb, a new III-V alloy for long-wavelength infrared detector applications, by low-pressure metalorganic chemical vapor deposition. In_1-xTl_xSb with good surface morphology was obtained on both GaAs and InSb substrates at a growth temperature of 455 °C. X-ray diffraction measurements showed resolved peaks of In_1-xTl_xSb and InSb films. Infrared absorption spectrum of In_1-xTl_xSb showed a shift toward lower energies compared to InSb spectrum. Hall mobility data on In_1-xTl_xSb/InSb/GaAs structure showed enhanced mobility at low temperatures compared to InSb/GaAs structure. [reprint (PDF)]
15.	High performance quantum cascade lasers (~11 μm) operating at high temperature (T>= 425K) A. Tahraoui, A. Matlis, S. Slivken, J. Diaz, and M. Razeghi Applied Physics Letters 78 (4)-- January 22, 2001 ...[Visit Journal] We report record-low threshold current density and high output power for λ ∼ 11 μm Al_0.48In_0.52As/Ga_0.47In_0.53As quantum cascade lasers operating up to 425 K. The threshold current density is 1.1, 3.83, and 7.08 kA/cm² at 80, 300, and 425 K, respectively, for 5 μs pulses at a 200 Hz repetition rate. The cavity length is 3 mm with a stripe width of 20 μm. The maximum peak output power per facet is 1 W at 80 K, 0.5 W at 300 K, and more than 75 mW at 425 K. The characteristic temperature of these lasers is 174 K between 80 and 300 K and 218 K in the range of 300–425 K. [reprint (PDF)]
15.	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)]
15.	Dark current reduction in microjunction-based compound electron barrier type-II InAs/InAs1-xSbx superlattice-based long-wavelength infrared photodetectors Romain Chevallier, Abbas Haddadi, Manijeh Razeghi Proc. SPIE 10540, Quantum Sensing and Nano Electronics and Photonics XV Page. 1054007-1-- January 26, 2018 ...[Visit Journal] Reduction of dark current density in microjunction-based InAs/InAs_1-xSb_x type-II superlattice long-wavelength infrared photodetectors was demonstrated. A double electron barrier design was used to suppress both generation-recombination and surface dark currents. The photodetectors exhibited high surface resistivity after passivation with SiO₂, which permits the use of small size features without having strong surface leakage current degrading the electrical performance. Fabricating a microjunction structure (25×25 μm² mesas with 10×10 μm² microjunctions) with this photodetector double barrier design results in a dark current density of 6.3×10^-6 A/cm² at 77 K. The device has an 8 μm cut-off wavelength at 77 K and exhibits a quantum efficiency of 31% for a 2 μm-thick absorption region, which results in a specific detectivity value of 1.2×10¹² cm·Hz^1/2/W at 77 K. [reprint (PDF)]
15.	III-Nitride/Ga2O3 heterostructure for future power electronics: opportunity and challenges Nirajman Shrestha, Jun Hee Lee, F. H. Teherani, Manijeh Razeghi Proc. of SPIE Vol. 12895, Quantum Sensing and Nano Electronics and Photonics XX, 128950B (28 January - 1 February 2024, San Francisco)http://dx.doi.org/10.1117/12.3011688 ...[Visit Journal] Ga2O3 has become the new focal point of high-power semiconductor device research due to its superior capability to handle high voltages in smaller dimensions and with higher efficiencies compared to other commercialized semiconductors. However, the low thermal conductivity of the material is expected to limit device performance. To compensate for the low thermal conductivity of Ga2O3 and to achieve a very high density 2-dimensional electron gas (2DEG), an innovative idea is to combine Ga2O3 with III-Nitrides (which have higher thermal conductivity), such as AlN. However, metal-polar AlN/β-Ga2O3 heterojunction provides type-II heterojunction which are beneficial for optoelectronic application, because of the negative value of specific charge density. On the other hand, N-polar AlN/β- Ga2O3 heterostructures provide higher 2DEG concentration and larger breakdown voltage compared to conventional AlGaN/GaN devices. This advancement would allow the demonstration of RF power transistors with a 10x increase in power density compared to today’s State of the Art (SoA) and provide a solution to size, weight, and power-constrained applications [reprint (PDF)]
15.	Injector doping level dependent continuous-wave operation of InP-based QCLs at λ~ 7.3 µm above room temperature J.S. Yu, S. Slivken, and M. Razeghi Semiconductor Science and Technology (SST), Vol. 25, No. 12, p. 125015-- December 1, 2010 ...[Visit Journal] We report the continuous-wave (CW) operation of InGaAs/InAlAs quantum cascade lasers (QCLs) operating at λ ~ 7.3 µm above room temperature. The injector doping level–dependent CW characteristics above room temperature are investigated for doping densities between 7 × 10¹⁶ cm⁻³ and 2 × 10¹⁷ cm⁻³. The device performance, i.e. threshold current density, output power, operating temperature and characteristic temperature, depends strongly on the injector doping density. For a relatively low injector doping density of 7 × 10¹⁶ cm⁻³, a high-reflectivity-coated 10 µm wide and 4 mm long laser exhibits an improved device performance with an output power of 152 mW and a threshold current density of 1.37 kA cm⁻² at 298 K under CW mode, operating up to 343 K. The thermal characteristics are also analyzed by the estimation from the experimentally measured data for the QCLs with different injector doping densities. [reprint (PDF)]
15.	8.5 μm Room Temperature Quantum Cascade Lasers Grown by Gas-Source Molecular Beam Epitaxy S. Slivken and M. Razeghi SPIE Conference, San Jose, CA, -- January 28, 1998 ...[Visit Journal] We report room-temperature pulsed-mode operation of 8.5 μm quantum cascade lasers grown by gas-source molecular beam epitaxy. The theory necessary to understand the operation of the laser is presented and current problems are analyzed. Very good agreement is shown to exist between theoretical and experimental emission wavelengths. The high- temperature operation is achieved with 1 μs pulses at a repetition rate of 200 Hz. Peak output power in these conditions is in excess of 700 mW per 2 facets at 79 K and 25 mW at 300 K. Threshold current as a function of temperature shows an exponential dependence with T₀ equals 188 K for a 1.5 mm cavity. [reprint (PDF)]
15.	High‐quality GaAs/Ga0.49In0.51P superlattices grown on GaAs and silicon substrates by low‐pressure metalorganic chemical vapor deposition Available M. Razeghi; Ph. Maurel; F. Omnes; M. Defour; C. Boothroyd; W. M. Stobbs; M. Kelly J. Appl. Phys. 63, 4511–4514 (1988) -- May 1, 1988 ...[Visit Journal] We report the successful growth of Ga0.49 Iuo.5 ! P-GaAs superlattices on GaAs and Si substrates by low-pressure metalorganic chemical vapor deposition. The high quality of the structure grown on GaAs and silicon substrates has been evidenced by transmission electron microscopy photographs, that show very sharp interfaces between GaAs wells and Gao.49InO.51 P barriers, with perfect control of thicknesses and compositions. Classical Hall measurements performed on the sample further demonstrated the presence of a twodimensional electron ga.<; with a mobility at T = 4 K , fL (4 K) = 50000 cm2 1V Is, and a carrier concentration n _ (4 K) = 2,9 X 1011 em -2. GaAs/Gao.49 InO. 51 P superlattices have been used, as well as buffer layer in order to grow GaAs on silicon substrates. Mirrorlike single-crystal GaAs has thus been obtained. A GaInP IGaAs heterostructure with electron HaH mobility as high as 6000 cm2 /V Is at 300 K and 80000 cm2 /V Is at 4 K has been grown, which is the highest mobility that has yet been reported for these materials, [reprint (PDF)]
15.	High Detectivity InAs Quantum-Dot Infrared Photodetectors Grown on InP by Metalorganic Chemical Vapor Deposition W. Zhang, H. Lim, M. Taguchi, S. Tsao, B. Movaghar, and M. Razeghi Applied Physics Letters, 86 (19)-- May 9, 2005 ...[Visit Journal] We report a high-detectivity InAs quantum-dot infrared photodetector. The InAs quantum dots were grown by self-assembly on InP substrates via low-pressure metal–organic chemical–vapor deposition. Highly uniform quantum dots with a density of 4×10¹⁰ cm² were grown on a GaAs/InP matrix. Photoresponse was observed at temperatures up to 160 K with a peak of 6.4 µm and cutoff of 6.6 µm. Very low dark currents and noise currents were obtained by inserting Al_0.48In_0.52As current blocking layers. The background-limited performance temperature was 100 K. A detectivity of 1.0×10¹⁰ cm·Hz^½/W was obtained at 77 K with a bias of –1.1 V. [reprint (PDF)]
15.	Radiometric characterization of long-wavelength infrared type II strained layer superlattice focal plane array under low-photon irradiance conditions J. Hubbs, V. Nathan, M. Tidrow, and M. Razeghi Optical Engineering, Vol. 51, No. 6, p. 064002-1-- June 15, 2012 ...[Visit Journal] We present the results of the radiometric characterization of an “M” structure long wavelength infrared Type-II strained layer superlattice(SLS) infrared focal plane array (IRFPA) developed by Northwestern University (NWU). The performance of the M-structure SLS IRFPA was radiometrically characterized as a function of photon irradiance, integration time, operating temperature, and detector bias. Its performance is described using standard figures of merit: responsivity, noise, and noise equivalent irradiance. Assuming background limited performance operation at higher irradiances, the detector quantum efficiency for the SLS detector array is approximately 57%. The detector dark density at 80 K is 142 μA∕cm², which represents a factor of seven reduction from previously measured devices. [reprint (PDF)]
15.	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)]
15.	Solar-Blind Deep UV Avalanche Photodetectors Using Reduced Area Epitaxy Lakshay Gautam , Junhee Lee, Michael Richards, and Manijeh Razeghi , Lakshay Gautam, Manijeh Razeghi, IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 59, NO. 6, 10.1109/JQE.2023.3325254 ...[Visit Journal] We report high gain avalanche photodetectors operating in the deep UV wavelength regime. The high gain was leveraged through reduced area epitaxy by patterning AlN on Sapphire substrate. This helps in a substantial reduction of crack formation due to overgrowth on individually isolated AlN mesas. Reproducible gain on the order of 105 was reported for multiple diodes in different areas of 320 × 256 focal plane array. [reprint (PDF)]
15.	High performance long wavelength infrared mega-pixel focal plane array based on type-II superlattices P. Manurkar, S.R. Darvish, B.M. Nguyen, M. Razeghi and J. Hubbs Applied Physics Letters, Vol. 97, No 19, p. 193505-1-- November 8, 2010 ...[Visit Journal] A large format 1k × 1k focal plane array (FPA) is realized using type-II superlattice photodiodes for long wavelength infrared detection. Material growth on a 3 in. GaSb substrate exhibits a 50% cutoff wavelength of 11 μm across the entire wafer. The FPA shows excellent imaging. Noise equivalent temperature differences of 23.6 mK at 81 K and 22.5 mK at 68 K are achieved with an integration time of 0.13 ms, a 300 K background and f/4 optics. We report a dark current density of 3.3×10⁻⁴ A·cm⁻² and differential resistance-area product at zero bias R₀A of 166 Ω·cm² at 81 K, and 5.1×10⁻⁵ A·cm⁻² and 1286 Ω·cm², respectively, at 68 K. The quantum efficiency obtained is 78%. [reprint (PDF)]
15.	Ultraviolet Detector Materials and Devices Studied by Femtosecond Nonlinear Optical Techniques M. Wraback, H. Shen, P. Kung, M. Razeghi, J.C. Carrano, T. Li, and J.C. Campbell SPIE Conference, San Jose, CA, -- January 26, 2000 ...[Visit Journal] Femtosecond nonlinear optical techniques have been employed in the study of carrier dynamics and transport in UV detector materials. Visible femtosecond pulses derived from the signal beam of a 250 kHz regenerative amplifier-pumped optical parametric amplifier were frequency doubled to obtain pulses tunable from 250 nm to 375 nm. Time-resolved reflectivity experiments indicate that the room-temperature carrier lifetime in GaN grown by double lateral epitaxial overgrowth is about 3 times longer than that of GaN grown on sapphire without benefit of this technique. The electron velocity-field characteristics and saturation velocity in GaN have been obtained form time-resolved studies of electroabsorption in a GaN p-i-n diode. The peak steady- state velocity of 1.9x10⁷ cm/s in this device occurs at 225 kV/cm. Time-resolved transmission measurements have been used to monitor ultrafast carrier relaxation phenomena in a thin AlGaN layer with bandgap in the solar blind region of the spectrum. Excitation intensity and wavelength dependent studies of the photoinduced bleaching decays suggest that they are primarily governed by trapping in a high density of sub-bandgap defect levels. [reprint (PDF)]
15.	MOCVD grown β-Ga₂O₃ metal-oxide-semiconductor field effect transistors on sapphire Ji-Hyeon Park , Ryan McClintock, Alexandre Jaud, Arash Dehzangi , Manijeh Razeghi Applied Physics Express 12, 095503-- August 28, 2019 ...[Visit Journal] We fabricated β-Ga₂O₃:Si metal-oxide field-effect transistors (MOSFETs) on c-plane sapphire substrates which typically showed maximum drain current of 100 mA·mm⁻¹. β-Ga₂O₃:Si thin films were realized on c-plane sapphire substrates through a combination of metalorganic chemical vapor deposition and post-annealing. The MOSFET device presented excellent on/off drain current ratio of ∼10¹¹ with very low gate leakage current, sharp pinch off behavior, and a breakdown voltage of 400 V at VG = −40 V. The growth and fabrication of β-Ga₂O₃:Si MOSFETs on c-plane sapphire is valuable to its demonstration of the great potential for future high-power electronic devices. [reprint (PDF)]
15.	Mid-infrared quantum cascade lasers with high wall plug efficiency Y. Bai, B. Gokden, S. Slivken, S.R. Darvish, S.A. Pour, and M. Razeghi SPIE Proceedings, San Jose, CA Volume 7222-0O-- January 26, 2009 ...[Visit Journal] We demonstrate optimization of continuous wave (cw) operation of 4.6 µm quantum cascade lasers (QCLs). A 19.7 µm by 5 mm, double channel processed device exhibits 33% cw WPE at 80 K. Room temperature cw WPE as high as 12.5% is obtained from a 10.6 µm by 4.8 mm device, epilayer-down bonded on a diamond submount. With the semi-insulating regrowth in a buried ridge geometry, 15% WPE is obtained with 2.8 W total output power in cw mode at room temperature. This accomplishment is achieved by systematically decreasing the parasitic voltage drop, reducing the waveguide loss and improving the thermal management. [reprint (PDF)]

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