Center for Quantum Devices - Most Downloaded Journal Articles

Page 12 of 30: Prev << 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 >> Next (738 Items)

16.	Internal Stress Around Micropipes in 6H-SiC Substrates H. Ohsato, T. Kato, T. Okuda and M. Razeghi SPIE Conference, San Jose, CA, -- January 27, 1999 ...[Visit Journal] 6H-SiC single crystals are expected to be suitable substrates for thin film growth of the wide bandgap semiconductor (GaN, because it has a small lattice mismatch with GaN. Moreover, SiC single crystals are also expected for high-power and high- temperature electric applications because of its wide band gap, high breakdown voltage, high thermal conductivity and high temperature stability. Single crystals with large size used for electronic devices can be grown on seed crystals only by the modified Lely method based on sublimation deposition. But, single crystals have serious defects so called micropipes. These micropipes penetrate almost along the [001] direction. The internal strain around micropipes was investigated using the polarizing optical microscope for the purpose of clarifying the formation mechanisms and decreasing the amount of micropipes. A special interference figure was found around a micropipe under the crossed polars on the polarizing microscope. In this work, the special interference figure around micropipes due to internal stress was explained, and the magnitude and distribution of the stress was measured by means of photoelasticity and the mapping of Raman spectra. [reprint (PDF)]
16.	High Performance Type-II InAs/GaSb Superlattice Photodiodes H. Mohseni, Y. Wei, and M. Razeghi SPIE Conference, San Jose, CA, -- January 22, 2001 ...[Visit Journal] We report on the demonstration of high performance p-i-n photodiodes based on Type-II InAs/GaSb superlattices operating in the very long wavelength infrared (VLWIR) range at 80 K. Material is grown by molecular beam epitaxy on GaSb substrates with excellent crystal quality as evidenced by x-ray diffraction and atomic force microscopy. The processed devices with a 50% cutoff wavelength of λ_c equals 22 μm show a peak current responsivity about 5.5 A/W at 80 K. The use of binary layers in the superlattice has significantly enhanced the uniformity and reproducibility of the energy gap. The 90% to 10% cut-off energy width of these devices is on the order of 2 kT which is about four times smaller compared to the devices based on InAs/Ga1-xInxSb superlattices. Similar photovoltaic devices with cut-off wavelengths up to 25 μm have been measured at 80 K. Our experimental results shows excellent uniformity over a three inch wafer area, indicating the possibility of VLWIR focal plane arrays based on Type-II superlattices. [reprint (PDF)]
16.	Intrinsic AlGaN photodetectors for the entire compositional range D. Walker, X. Zhang, A. Saxler, P. Kung, J. Xu, and M. Razeghi SPIE Conference, San Jose, CA, -- February 12, 1997 ...[Visit Journal] Al_xGa_1-xN ultraviolet photoconductors with cut- off wavelengths from 365 nm to 200 nm have been fabricated and characterized. Various characteristics of the devices, such as photoresponse, voltage-dependent responsivity, frequency-dependent responsivity and noise spectral density, were measured and cross-referenced with optical, electrical and structural characteristics of the material to provide information about the mechanisms taking place during detection. The maximum detectivity reached 5.5 X 10⁸ cm·Hz^½/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 msec. The frequency-dependent noise-spectrum shows that it is dominated by Johnson-noise at high frequencies for low Al-composition samples. [reprint (PDF)]
16.	Demonstration of InAsSb/AlInSb Double Heterostructure Detectors for Room Temperature Operation in the 5–8 μm Wavelength Range J.S. Wojkowski, H. Mohseni, J.D. Kim, and M. Razeghi SPIE Conference, San Jose, CA, -- January 27, 1999 ...[Visit Journal] We report the first demonstration of InAsSb/AlInSb double heterostructure detectors for room temperature operation. The structures were grown in a solid source molecular beam epitaxy reactor on semi-insulating GaAs substrate. The material was processed to 400x400 micrometer mesas using standard photolithography, etching, and metallization techniques. No optical immersion or surface passivation was used. The photovoltaic detectors showed a cutoff wavelength at 8 micrometer at 300 K. The devices showed a high quantum efficiency of 40% at 7 μm at room temperature. A responsivity of 300 mA/W was measured at 7 μm under a reverse bias of 0.25 V at 300 K resulting in a Johnson noise limited detectivity of 2x10⁸ cm·Hz^½/W. [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)]
16.	Transport properties in n-type InSb films grown by metalorganic chemical vapor deposition S.N. Song, J.B. Ketterson, Y.H. Choi, R. Sudharsanan, and M. Razeghi Applied Physics Letters 63 (7)-- August 16, 1993 ...[Visit Journal] We have measured the temperature and magnetic field dependence of the Hall mobility and transverse magnetoresistance in n-type InSb films epitaxially grown on GaAs substrates by metalorganic chemical vapor deposition. The films show a giant magnetoresistance: e.g., at 240 K the resistivity increases over 20 times at a magnetic field of 5 T; the low field coefficient of resistivity at 77 K is as high as 47.5 μ·Ω· cm/G. The Hall mobility decreases with magnetic field and saturates at higher fields. By taking the interface carrier transport into account, the observed field dependence of the Hall mobility and magnetoresistance may be understood based on a two-layer model. [reprint (PDF)]
16.	High-performance InAs quantum-dot infrared photodetectors grown on InP substrate operating at room temperature H. Lim, S. Tsao, W. Zhang, and M. Razeghi Applied Physics Letters, Vol. 90, No. 13, p. 131112-1-- March 26, 2007 ...[Visit Journal] The authors report a room temperature operating InAs quantum-dot infrared photodetector grown on InP substrate. The self-assembled InAs quantum dots and the device structure were grown by low-pressure metal-organic chemical vapor deposition. The detectivity was 2.8×10¹¹ cm·Hz^1/2/W at 120 K and a bias of −5 V with a peak detection wavelength around 4.1 μm and a quantum efficiency of 35%. Due to the low dark current and high responsivity, a clear photoresponse has been observed at room temperature, which gives a detectivity of 6.7×10⁷ cm·Hz^1/2/W. [reprint (PDF)]
16.	Effect of sidewall surface recombination on the quantum efficiency in a Y₂O₃ passivated gated type-II InAs/GaSb long-infrared photodetector array G. Chen, A. M. Hoang, S. Bogdanov, A. Haddadi, S. R. Darvish, and M. Razeghi Appl. Phys. Lett. 103, 223501 (2013)-- November 25, 2013 ...[Visit Journal] Y₂O₃ was applied to passivate a long-wavelength infrared type-II superlattice gated photodetector array with 50% cut-off wavelength at 11 μm, resulting in a saturated gate bias that was 3 times lower than in a SiO₂ passivated array. Besides effectively suppressing surface leakage, gating technique exhibited its ability to enhance the quantum efficiency of 100 × 100 μm size mesa from 51% to 57% by suppressing sidewall surface recombination. At 77 K, the gated photodetector showed dark current density and resistance-area product at −300 mV of 2.5 × 10⁻⁵ A/cm² and 1.3 × 10⁴ Ω·cm², respectively, and a specific detectivity of 1.4 × 10¹² Jones. [reprint (PDF)]
16.	High speed type-II superlattice based photodetectors transferred on sapphire Arash Dehzangi, Ryan McClintock, Donghai Wu, Jiakai Li, Stephen Johnson, Emily Dial and Manijeh Razeghi Applied Physics Express, Volume 12, Number 11-- October 3, 2019 ...[Visit Journal] We report the substrate transfer of InAs/GaSb/AlSb based type-II superlattice (T2SL) e-SWIR photodetector from native GaSb substrates to low loss sapphire substrate in order to enhance the frequency response of the device. We have demonstrated the damage-free transfer of T2SL-based thin-films to sapphire substrate using top–down processing and a chemical epilayer release technique. After transfer the −3 dB cut-off frequency increased from 6.4 GHz to 17.2 GHz, for 8 μm diameter circular mesas under -15 V applied bias. We also investigated the cut-off frequency verses applied bias and lateral scaling to assess the limitations for even higher frequency performance. Direct Link [reprint (PDF)]
16.	InAs quantum dot infrared photodetectors on InP by MOCVD W. Zhang, H. Lim, M. Taguchi, A. Quivy and M. Razeghi SPIE Conference, San Jose, CA, Vol. 6127, pp. 61270M -- January 23, 2006 ...[Visit Journal] We report our recent results of InAs quantum dots grown on InP substrate by low-pressure metalorganic chemical vapor deposition (MOCVD) for the application of quantum dot infrared photodetector (QDIP). We have previously demonstrated the first InP-based QDIP with a peak detection wavelength at 6.4 µm and a detectivity of 10¹⁰ cm·Hz^½/W at 77K. Here we show our recent work toward shifting the detection wavelength to the 3-5 µm middlewavelength infrared (MWIR) range. The dependence of the quantum dot on the growth conditions is studied by atomic force microscopy, photoluminescence and Fourier transform infrared spectroscopy. Possible ways to increase the quantum efficiency of QDIPs are discussed. [reprint (PDF)]
16.	Aluminum nitride films on different orientations of sapphire and silicon K. Dovidenko, S. Oktyabrsky, J. Narayan, and M. Razeghi Journal of Applied Physics79 (5)-- March 1, 1996 ...[Visit Journal] The details of epitaxial growth and microstrictural characteristics of AlN films grown on sapphire (0001), (1012) and Si (100), (111) substrates were investigated using plan‐view and cross‐sectional high‐resolution transmission electron microscopy and x‐ray diffraction techniques. The films were grown by metalorganic chemical vapor deposition using TMA1+NH3+N2 gas mixtures. Different degrees of epitaxy were observed for the films grown on α‐Al₂O₃ and Si substrates in different orientations. The epitaxial relationship for (0001) sapphire was found to be (0001)AlN∥(0001)sap with in‐plane orientation relationship of [0110]AlN∥[1210]sap. This is equivalent to a 30° rotation in the basal (0001) plane. For (1012) sapphire substrates, the epitaxial relationship was determined to be (1120)AlN∥(1012)sap with the in‐plane alignment of [0001]AlN∥[1011]sap. The AlN films on (0001) α‐Al₂O₃ were found to contain inverted domain boundaries and a/3〈1120〉 threading dislocations with the estimated density of 10¹⁰ cm⁻². The density of planar defects (stacking faults) found in AlN films was considerably higher in the case of (1012) compared to (0001) substrates. Films on Si substrates were found to be highly textured c axis oriented when grown on (111) Si, and c axis textured with random in‐plane orientation on (100) Si. The role of thin‐film defects and interfaces on device fabrication is discussed. [reprint (PDF)]
16.	Non-equilibrium radiation of long wavelength InAs/GaSb superlattice photodiodes D. Hoffman, A. Hood, F. Fuchs and M. Razeghi Journal of Applied Physics 99-- February 15, 2006 ...[Visit Journal] The emission behavior of binary-binary type-II InAs/GaSb superlattice photodiodes has been studied in the spectral range between 8 and 13 μm. With a radiometric calibration of the experimental setup the internal and external quantum efficiencies have been determined in the temperature range between 80 and 300 K for both the negative and positive luminescences. [reprint (PDF)]
16.	Multi-color 4–20 μm In-P-based Quantum Well Infrared Photodetectors C. Jelen, S. Slivken, G.J. Brown, and M. Razeghi SPIE Conference, San Jose, CA, -- January 27, 1999 ...[Visit Journal] In order to tune the wavelength of lattice-matched QWIP detectors over the range from 4 - 20 &mum, new designs are demonstrated for the first time which combine InGaAlAs and InGaAsP layers lattice-matched to InP and grown by gas-source molecular beam epitaxy. We demonstrate the first long-wavelength quantum well infrared photodetectors using the lattice-matched n-doped InGaAlAs/InP materials system. Samples with AlAs mole fractions of 0.0, 0.1, and 0.15 result in cutoff wavelengths of 8.5, 13.3, and 19.4 μm, respectively. A 45 degree facet coupled illumination responsivity of R equals 0.37 A/W and detectivity of D*(λ) equals 1x10⁹ cm·Hz^½·W^-1 at T = 77 K, for a cutoff wavelength λ_c equals 13.3 μm have been achieved. Based on the measured intersubband photoresponse wavelength, a null conduction band offset is expected for In_0.52Ga_0.21Al_0.27As/InP heterojunctions. We also report quantum well infrared photodetector structures of In_0.53Ga_0.47As/Al_0.48In_0.52As grown on InP substrate with photoresponse at 4 μm suitable for mid-wavelength infrared detectors. These detectors exhibit a constant peak responsivity of 30 mA/W independent of temperature in the range from T equals 77 K to T equals 200 K. Combining these two materials, we report the first multispectral detectors that combine lattice-matched quantum wells of InGaAs/InAlAs and InGaAs/InP. Utilizing two contacts, a voltage tunable detector with (lambda) p equals 8 micrometer at a bias of V equals 5 V and λ_p equals 4 μm at V equals 10 V is demonstrated. [reprint (PDF)]
16.	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)]
16.	Generation-recombination and trap-assisted tunneling in long wavelength infrared minority electron unipolar photodetectors based on InAs/GaSb superlattice F. Callewaert, A.M. Hoang, and M. Razeghi Applied Physics Letters, 104, 053508 (2014)-- February 6, 2014 ...[Visit Journal] A long wavelength infrared minority electron unipolar photodetector based on InAs/GaSb type-II superlattices is demonstrated. At 77 K, a dark current of 3 × 10⁻⁵ A/cm² and a differential resistance-area of 3 700 Ω·cm² are achieved at the turn-on bias, with a 50%-cutoff of 10.0 μm and a specific detectivity of 6.2 × 10¹¹ Jones. The dark current is fitted as a function of bias and temperature using a model combining generation-recombination and trap-assisted tunneling. Good agreement was observed between the theory and the experimental dark current. [reprint (PDF)]
16.	Optical Investigations of GaAs-GaInP Quantum Wells Grown on the GaAs, InP, and Si Substrates H. Xiaoguang, M. Razeghi Applied Physics Letters 61 (14)-- October 5, 1992 ...[Visit Journal] We report the first photoluminescence investigation of GaAs‐Ga_0.51In_0.49P lattice matched multiquantum wells grown by the low pressure metalorganic chemical vapor deposition simultaneously in the same run on GaAs, Si, and InP substrates. The sharp photoluminescence peaks indicate the high quality of the samples on three different substrates. The temperature dependence of the photoluminescence indicates that the intrinsic excitonic transitions dominate at low temperature and free‐carrier recombinations at room temperature. The photoluminescence peaks of the samples grown on Si and InP substrates shift about 15 meV from the corresponding peaks of the sample grown on the GaAs substrate. Two possible interpretations are provided for the observed energy shift. One is the diffusion of In along the dislocation threads from GaInP to GaAs and another is the localized strain induced by defects and In segregations. [reprint (PDF)]
16.	Background limited performance of long wavelength infrared focal plane arrays fabricated from M-structure InAs-GaSb superlattices P.Y. Delaunay, B.M. Nguyen, D. Hoffman, E.K. Huang, and M. Razeghi IEEE Journal of Quantum Electronics, Vol. 45, No. 2, p. 157-162.-- February 1, 2009 ...[Visit Journal] The recent introduction of a M-structure design improved both the dark current and R₀A performances of Type-II InAs-GaSb photodiodes. A focal plane array fabricated with this design was characterized at 81 K. The dark current of individual pixels was measured between 1.1 and 1.6 nA, 7 times lower than previous superlattice FPAs. This led to a higher dynamic range and longer integration times. The quantum efficiency of detectors without antireflective coating was 74%. The noise equivalent temperature difference reached 23 mK, limited only by the performance of the testing system and the read out integrated circuit. Background limited performances were demonstrated at 81 K for a 300 K background. [reprint (PDF)]
16.	Pulsed metalorganic chemical vapor deposition of high quality AlN/GaN superlattices for intersubband transitions C. Bayram, B. Fain, N. Pere-Laperne, R. McClintock and M. Razeghi SPIE Proceedings, San Jose, CA Volume 7222-12-- January 26, 2009 ...[Visit Journal] A pulsed metalorganic chemical vapor deposition (MOCVD) technique, specifically designed for high quality AlN/GaN superlattices (SLs) is introduced. Optical quality and precise controllability over layer thicknesses are investigated. Indium is shown to improve interface and surface quality. An AlN/GaN SL designed for intersubband transition at a telecommunication wavelength of ~1.5 µm, is grown, and processed for intersubband (ISB) absorption measurements. Room temperature measurements show intersubband absorption centered at 1.49 µm. Minimal (n-type) silicon doping of the well is shown to be crucial for good ISB absorption characteristics. The potential to extend this technology into the far infrared and even the terahertz (THz) region is also discussed. [reprint (PDF)]
16.	High peak power 16 m InP-related quantum cascade laser A. Szerlinga,∗, S. Slivkenb, M. RazeghibaInstytut Opto-Electronics Review 25, pp. 205–208-- July 22, 2017 ...[Visit Journal] tIn this paper ∼16 μm-emitting multimode InP-related quantum cascade lasers are presented with themaximum operating temperature 373 K, peak and average optical power equal to 720 mW and 4.8 mW at 303 K, respectively, and the characteristic temperature (T₀) 272 K. Two types of the lasers were fabricatedand characterized: the lasers with a SiO₂ layer left untouched in the area of the metal-free window ontop of the ridge, and the lasers with the SiO₂layer removed from the metal-free window area. Dual-wavelength operation was obtained, at ∼15.6 μm (641 cm⁻¹) and at ∼16.6 μm (602 cm⁻¹) for laserswith SiO₂-removed, while within the emission spectrum of the lasers with SiO₂-left untouched only the former lasing peak was present. The parameters of these devices like threshold current, optical power and emission wavelength are compared. Lasers without the SiO₂ layer showed ∼15% lower threshold current than these ones with the SiO₂ layer. The optical powers for lasers without SiO₂ layer were almost twice higher than for the lasers with the SiO₂ layer on the top of the ridge. [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.	Bias–selectable nBn dual–band long–/very long–wavelength infrared photodetectors based on InAs/InAsSb/AlAsSb type–II superlattices Abbas Haddadi, Arash Dehzangi, Romain Chevallier, Sourav Adhikary, & Manijeh Razeghi Nature Scientific Reports 7, Article number: 3379-- June 13, 2017 ...[Visit Journal] Type–II superlattices (T2SLs) are a class of artificial semiconductors that have demonstrated themselves as a viable candidate to compete with the state–of–the–art mercury–cadmium–telluride material system in the field of infrared detection and imaging. Within type–II superlattices, InAs/InAs_1−xSb_x T2SLs have been shown to have a significantly longer minority carrier lifetime. However, demonstration of high–performance dual–band photodetectors based on InAs/InAs_1−xSb_x T2SLs in the long and very long wavelength infrared (LWIR & VLWIR) regimes remains challenging. We report the demonstration of high–performance bias–selectable dual–band long–wavelength infrared photodetectors based on new InAs/InAsSb/AlAsSb type–II superlattice design. Our design uses two different bandgap absorption regions separated by an electron barrier that blocks the transport of majority carriers to reduce the dark current density of the device. As the applied bias is varied, the device exhibits well–defined cut–off wavelengths of either ∼8.7 or ∼12.5 μm at 77 K. This bias–selectable dual–band photodetector is compact, with no moving parts, and will open new opportunities for multi–spectral LWIR and VLWIR imaging and detection. [reprint (PDF)]
16.	TEG IN LP-MO CVD Ga 0 4 7 ln 0 S3 As-lnP SUPERLATTICE M. RAZEGHIM. A. POISSONJ. P. LARIVAINB. de CREMOUXJ. P. DUCHEMIN ELECTRONICS LETTERs, 1982 ,Vol. 18-- April 15, 1982 ...[Visit Journal] We report the first successful growth of Ga o .4. 7 In 0 . J3 As-InPsuperlattice by the low-pressure metalorganic chemicalvapour deposition technique, and evidence for TEG proper-ties in these structures. [reprint (PDF)]
16.	Fabrication of GaN Nanotubular Material using MOCVD with an Aluminium Oxide Membrane W.G. Jung, S.H. Jung, P. Kung, and M. Razeghi Nanotechnology 17-- January 1, 2006 ...[Visit Journal] GaN nanotubular material is fabricated with an aluminium oxide membrane in MOCVD. SEM, XRD, TEM and PL are employed to characterize the fabricated GaN nanotubular material. An aluminium oxide membrane with ordered nanoholes is used as a template. Gallium nitride is deposited at the inner wall of the nanoholes in the aluminium oxide template, and the nanotubular material with high aspect ratio is synthesized using the precursors of TMG and ammonia gas. Optimal synthesis conditions in MOCVD are obtained successfully for the gallium nitride nanotubular material in this research. The diameter of the GaN nanotube fabricated is approximately 200–250 nm and the wall thickness is about 40–50 nm. [reprint (PDF)]
16.	Demonstration of negative differential resistance in GaN/AlN resonant tunneling didoes at room temperature Z. Vashaei, C. Bayram and M. Razeghi Journal of Applied Physics, Vol. 107, No. 8, p. 083505-- April 15, 2010 ...[Visit Journal] GaN/AlN resonant tunneling diodes (RTD) were grown by metal-organic chemical vapor deposition (MOCVD) and negative differential resistance with peak-to-valley ratios as high as 2.15 at room temperature was demonstrated. Effect of material quality on RTDs’ performance was investigated by growing RTD structures on AlN, GaN, and lateral epitaxial overgrowth GaN templates. Our results reveal that negative differential resistance characteristics of RTDs are very sensitive to material quality (such as surface roughness) and MOCVD is a suitable technique for III-nitride-based quantum devices. [reprint (PDF)]
16.	Room temperature single-mode terahertz sources based on intracavity difference-frequency generation in quantum cascade lasers Q.Y. Lu, N. Bandyopadhyay, S. Slivken, Y. Bai and M. Razeghi Applied Physics Letters, Vol. 99, Issue 13, p. 131106-1-- September 26, 2011 ...[Visit Journal] We demonstrate room temperature single-mode THz emission at 4 THz based on intracavity difference-frequency generation from mid-infrared dual-wavelength quantum cascade lasers. An integrated dual-period distributed feedback grating is defined on the cap layer to purify both mid-infrared pumping wavelengths and in turn the THz spectra. Single mode operation of the pumping wavelengths results in a single-mode THz operation with a narrow linewidth of 6.6 GHz. A maximum THz power of 8.5 μW with a power conversion efficiency of 10 μW/W² is obtained at room temperature. [reprint (PDF)]

Page 12 of 30: Prev << 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 >> Next (738 Items)