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1

Journal of Crystal Growth 298 (2007) 272275 Dislocation analysis in homoepitaxial GaInN/GaN light emitting  

E-Print Network [OSTI]

of GaInN/GaN-based light emitting diodes (LED) on quasi-bulk GaN with an atomically flat polished were much improved. The optical output power of the light emitting diode increased by more than one. Cathodoluminescence; A1. Threading dislocation density; A2. Homoepitaxial growth; B1. GaInN; B3. Light emitting diode

Wetzel, Christian M.

2

Green cubic GaInN/GaN light-emitting diode on microstructured silicon (100)  

SciTech Connect (OSTI)

GaInN/GaN light-emitting diodes free of piezoelectric polarization were prepared on standard electronic-grade Si(100) substrates. Micro-stripes of GaN and GaInN/GaN quantum wells in the cubic crystal structure were grown on intersecting (111) planes of microscale V-grooved Si in metal-organic vapor phase epitaxy, covering over 50% of the wafer surface area. Crystal phases were identified in electron back-scattering diffraction. A cross-sectional analysis reveals a cubic structure virtually free of line defects. Electroluminescence over 20 to 100??A is found fixed at 487?nm (peak), 516?nm (dominant). Such structures therefore should allow higher efficiency, wavelength-stable light emitters throughout the visible spectrum.

Stark, Christoph J. M.; Detchprohm, Theeradetch; Wetzel, Christian, E-mail: wetzel@ieee.org [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States) [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Future Chips Constellation, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180 (United States); Lee, S. C.; Brueck, S. R. J. [Department of Electrical and Computer Engineering and Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico 87106 (United States)] [Department of Electrical and Computer Engineering and Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico 87106 (United States); Jiang, Y.-B. [Department of Earth and Planetary Science, University of New Mexico, Albuquerque, New Mexico 87131 (United States)] [Department of Earth and Planetary Science, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

2013-12-02T23:59:59.000Z

3

Wavelength-resolved low-frequency noise of GaInN/GaN green light emitting diodes  

E-Print Network [OSTI]

Wavelength-resolved low-frequency noise of GaInN/GaN green light emitting diodes S. L. Rumyantseva well light emitting diodes. The light intensity noise was measured as a function of wavelength within the light emitting diode spectral emission line. The spectral noise density is found to increase

Wetzel, Christian M.

4

Surface plasmon enhanced InGaN light emitter Koichi Okamoto*a  

E-Print Network [OSTI]

is a very promising method for developing the super bright light emitting diodes (LEDs). Moreover, we foundGaN/GaN, light emitting diode, quantum well, internal quantum efficiency, solid-state light source 1. INTRODUCTION Since 1993, InGaN quantum wells (QW)-based light emitting diodes (LEDs) have been continuously

Okamoto, Koichi

5

Light extraction in individual GaN nanowires on Si for LEDs  

E-Print Network [OSTI]

GaN-based nanowires hold great promise for solid state lighting applications because of their waveguiding properties and the ability to grow nonpolar GaN nanowire-based heterostructures, which could lead to increased light ...

Zhou, Xiang

6

Sidewall passivation for InGaN/GaN nanopillar light emitting diodes  

SciTech Connect (OSTI)

We studied the effect of sidewall passivation on InGaN/GaN multiquantum well-based nanopillar light emitting diode (LED) performance. In this research, the effects of varying etch rate, KOH treatment, and sulfur passivation were studied for reducing nanopillar sidewall damage and improving device efficiency. Nanopillars prepared under optimal etching conditions showed higher photoluminescence intensity compared with starting planar epilayers. Furthermore, nanopillar LEDs with and without sulfur passivation were compared through electrical and optical characterization. Suppressed leakage current under reverse bias and four times higher electroluminescence (EL) intensity were observed for passivated nanopillar LEDs compared with unpassivated nanopillar LEDs. The suppressed leakage current and EL intensity enhancement reflect the reduction of non-radiative recombination at the nanopillar sidewalls. In addition, the effect of sulfur passivation was found to be very stable, and further insight into its mechanism was gained through transmission electron microscopy.

Choi, Won Hyuck; Abraham, Michael; Yu, Shih-Ying [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); You, Guanjun; Liu, Jie; Wang, Li; Xu, Jian, E-mail: jianxu@engr.psu.edu [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Mohney, Suzanne E., E-mail: mohney@ems.psu.edu [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2014-07-07T23:59:59.000Z

7

ORIGINAL ARTICLE Highly efficient GaAs solar cells by limiting light emission  

E-Print Network [OSTI]

ORIGINAL ARTICLE Highly efficient GaAs solar cells by limiting light emission angle Emily D Kosten1 solar cell under direct sunlight, light is received from the solar disk, but is re-emitted isotropically.1038/lsa.2013.1; published online 4 January 2013 Keywords: detailed balance; GaAs solar cell; light

Atwater, Harry

8

High efficiency light emitting diode with anisotropically etched GaN-sapphire interface  

E-Print Network [OSTI]

High efficiency light emitting diode with anisotropically etched GaN- sapphire interface M. H. Lo and optimization of a light-emitting diode projection micro-stereolithography three-dimensional manufacturingGaN micro-light emitting diodes Appl. Phys. Lett. 101, 231110 (2012) A bright cadmium-free, hybrid organic

9

Ultra High p-doping Material Research for GaN Based Light Emitters  

SciTech Connect (OSTI)

The main goal of the Project is to investigate doping mechanisms in p-type GaN and AlGaN and controllably fabricate ultra high doped p-GaN materials and epitaxial structures. Highly doped p-type GaN-based materials with low electrical resistivity and abrupt doping profiles are of great importance for efficient light emitters for solid state lighting (SSL) applications. Cost-effective hydride vapor phase epitaxial (HVPE) technology was proposed to investigate and develop p-GaN materials for SSL. High p-type doping is required to improve (i) carrier injection efficiency in light emitting p-n junctions that will result in increasing of light emitting efficiency, (ii) current spreading in light emitting structures that will improve external quantum efficiency, and (iii) parameters of Ohmic contacts to reduce operating voltage and tolerate higher forward currents needed for the high output power operation of light emitters. Highly doped p-type GaN layers and AlGaN/GaN heterostructures with low electrical resistivity will lead to novel device and contact metallization designs for high-power high efficiency GaN-based light emitters. Overall, highly doped p-GaN is a key element to develop light emitting devices for the DOE SSL program. The project was focused on material research for highly doped p-type GaN materials and device structures for applications in high performance light emitters for general illumination P-GaN and p-AlGaN layers and multi-layer structures were grown by HVPE and investigated in terms of surface morphology and structure, doping concentrations and profiles, optical, electrical, and structural properties. Tasks of the project were successfully accomplished. Highly doped GaN materials with p-type conductivity were fabricated. As-grown GaN layers had concentration N{sub a}-N{sub d} as high as 3 x 10{sup 19} cm{sup -3}. Mechanisms of doping were investigated and results of material studies were reported at several International conferences providing better understanding of p-type GaN formation for Solid State Lighting community. Grown p-type GaN layers were used as substrates for blue and green InGaN-based LEDs made by HVPE technology at TDI. These results proved proposed technical approach and facilitate fabrication of highly conductive p-GaN materials by low-cost HVPE technology for solid state lighting applications. TDI has started the commercialization of p-GaN epitaxial materials.

Vladimir Dmitriev

2007-06-30T23:59:59.000Z

10

Plasmonic nanoparticle enhanced light absorption in GaAs solar cells Keisuke Nakayama,a  

E-Print Network [OSTI]

Plasmonic nanoparticle enhanced light absorption in GaAs solar cells Keisuke Nakayama,a Katsuaki 22 September 2008 We demonstrate an improvement in efficiency of optically thin GaAs solar cells-ratio nanoparticles effectively increases the optical path of the incident light in the absorber layers resulting

Atwater, Harry

11

Electrical spin injection using GaCrN in a GaN based spin light emitting diode  

SciTech Connect (OSTI)

We have demonstrated electrical spin-injection from GaCrN dilute magnetic semiconductor (DMS) in a GaN-based spin light emitting diode (spin-LED). The remanent in-plane magnetization of the thin-film semiconducting ferromagnet has been used for introducing the spin polarized electrons into the non-magnetic InGaN quantum well. The output circular polarization obtained from the spin-LED closely follows the normalized in-plane magnetization curve of the DMS. A saturation circular polarization of ?2.5% is obtained at 200?K.

Banerjee, D.; Ganguly, S.; Saha, D., E-mail: dipankarsaha@iitb.ac.in [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076 (India); IITB-Monash Research Academy, Indian Institute of Technology Bombay, Mumbai 400076 (India); Adari, R.; Sankaranarayan, S.; Kumar, A. [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076 (India)] [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076 (India); Aldhaheri, R. W.; Hussain, M. A.; Balamesh, A. S. [Department of Electrical and Computer Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)] [Department of Electrical and Computer Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

2013-12-09T23:59:59.000Z

12

Collector-up light-emitting charge injection transistors in n-lnGaAs/lnAIAs/ plllnGaAs and n-lnGaAs/lnP/p-InGaAs heterostructures  

E-Print Network [OSTI]

Collector-up light-emitting charge injection transistors in n-lnGaAs/lnAIAs/ plllnGaAs and n (Received 23 November 1992; accepted for publication 4 March 1993) The realization of collector-up light for the collector stripe definition. Electrons, injected over the wide-gap heterostructure barrier (InAlAs or In

Luryi, Serge

13

Junction temperature, spectral shift, and efficiency in GaInN-based blue and green light emitting diodes  

E-Print Network [OSTI]

Keywords: GaInN/GaN Light emitting diode temperature Micro-Raman Photoluminescence Electroluminescence well light emitting diode (LED) dies is analyzed by micro-Raman, photoluminescence, cathodoluminescenceJunction temperature, spectral shift, and efficiency in GaInN-based blue and green light emitting

Wetzel, Christian M.

14

Comparison of electrostatic and localized plasmon induced light enhancement in hybrid InGaN/GaN quantum wells  

SciTech Connect (OSTI)

The light enhancement phenomena in InGaN/GaN multi-quantum wells (MQWs) infiltrated with metal nanoparticles (NPs) are studied using resonant and off-resonant localized plasmon interactions. The emission and recombination characteristics of carriers in InGaN/GaN MQW structures with inverted hexagonal pits (IHPs) are modified distinctly depending on the nature of their interaction with the metal NPs and with the pumping and emitted photons. It is observed that the emission intensity of light is significantly enhanced when the emission energy is off-resonant to the localized plasmon frequency of the metal nanoparticles. This results in enhanced emission from MQW due to Au nanoparticles and from IHPs due to Ag nanoparticles. At resonant-plasmon frequency of the Ag NPs, the emission from MQWs is quenched due to the re-absorption of the emitted photons, or due to the drift carriers from c-plane MQWs towards the NPs because of the Coulomb forces induced by the image charge effect.

Lin, Jie; Llopis, Antonio; Krokhin, Arkadii; Neogi, Arup, E-mail: arup@unt.edu [Department of Physics, University of North Texas, Denton, Texas 76203 (United States); Pereira, Sergio [CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Watson, Ian M. [SUPA, Institute of Photonics, University of Strathclyde, Glasgow (United Kingdom)

2014-06-16T23:59:59.000Z

15

Monolithic phosphor-free InGaN/GaN quantum dot wavelength converter white light emitting diodes  

SciTech Connect (OSTI)

We report the characteristics of phosphor-free self-organized InGaN/GaN quantum dot wavelength converter white light emitting diodes grown by plasma assisted molecular beam epitaxy. The exciting quantum dots, in which electrically injected carriers recombine, are blue-emitting and the converter dots are red-emitting. We have studied the effect of tuning the number of dot layers and the peak emission wavelength of the exciting and converter dots on the nature of the emitted white light, in terms of the chromaticity coordinates and correlated color temperature. Depending on the values of these wavelengths, color temperatures in the range of 4420–6700?K have been derived at a current density of 45?A/cm{sup 2} across multiple devices. The variation of the color temperature with change in injection current is found to be very small.

Jahangir, Shafat; Bhattacharya, Pallab, E-mail: pkb@eecs.umich.edu [Center for Photonics and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States); Pietzonka, Ines; Strassburg, Martin [OSRAM Opto Semiconductors GmbH, Leibnizstrasse 4, Regensburg (Germany)

2014-09-15T23:59:59.000Z

16

p-doping-free InGaN/GaN light-emitting diode driven by three-dimensional hole gas  

SciTech Connect (OSTI)

Here, GaN/Al{sub x}Ga{sub 1-x}N heterostructures with a graded AlN composition, completely lacking external p-doping, are designed and grown using metal-organic-chemical-vapour deposition (MOCVD) system to realize three-dimensional hole gas (3DHG). The existence of the 3DHG is confirmed by capacitance-voltage measurements. Based on this design, a p-doping-free InGaN/GaN light-emitting diode (LED) driven by the 3DHG is proposed and grown using MOCVD. The electroluminescence, which is attributed to the radiative recombination of injected electrons and holes in InGaN/GaN quantum wells, is observed from the fabricated p-doping-free devices. These results suggest that the 3DHG can be an alternative hole source for InGaN/GaN LEDs besides common Mg dopants.

Zhang, Zi-Hui; Tiam Tan, Swee; Kyaw, Zabu; Liu, Wei; Ji, Yun; Ju, Zhengang; Zhang, Xueliang [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore) [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Wei Sun, Xiao, E-mail: EXWSUN@ntu.edu.sg [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Department of Electronics and Electrical Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Volkan Demir, Hilmi, E-mail: VOLKAN@stanfordalumni.org [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Department of Electrical and Electronics, UNAM-Institute of Material Science and Nanotechnology, Bilkent University, Ankara TR-06800 (Turkey); Department of Physics, UNAM-Institute of Material Science and Nanotechnology, Bilkent University, Ankara TR-06800 (Turkey)

2013-12-23T23:59:59.000Z

17

Active region based on graded-gap InGaN/GaN superlattices for high-power 440- to 470-nm light-emitting diodes  

SciTech Connect (OSTI)

The structural and optical properties of light-emitting diode structures with an active region based on ultrathin InGaN quantum wells limited by short-period InGaN/GaN superlattices from both sides have been investigated. The dependences of the external quantum efficiency on the active region design are analyzed. It is shown that the use of InGaN/GaN structures as limiting graded-gap short-period superlattices may significantly increase the quantum efficiency.

Tsatsulnikov, A. F., E-mail: Andrew@beam.ioffe.ru; Lundin, W. V.; Sakharov, A. V.; Zavarin, E. E.; Usov, S. O.; Nikolaev, A. E.; Cherkashin, N. A.; Ber, B. Ya.; Kazantsev, D. Yu. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Mizerov, M. N. [Russian Academy of Sciences, Center for Microelectronics, Ioffe Physicotechnical Institute (Russian Federation); Park, Hee Seok [Samsung Electro-Mechanics Co. Ltd. (Korea, Republic of); Hytch, M.; Hue, F. [National Center for Scientific Research, Center for Material Elaboration and Structural Studies (France)

2010-01-15T23:59:59.000Z

18

Carrier recombination mechanisms and efficiency droop in GaInN/GaN light-emitting diodes  

SciTech Connect (OSTI)

We model the carrier recombination mechanisms in GaInN/GaN light-emitting diodes as R=An+Bn{sup 2} +Cn{sup 3} +f(n) , where f(n) represents carrier leakage out of the active region. The term f(n) is expanded into a power series and shown to have higher-than-third-order contributions to the recombination. The total third-order nonradiative coefficient (which may include an f(n) leakage contribution and an Auger contribution) is found to be 8×10{sup ?29} ?cm{sup 6} ?s{sup ?1} . Comparison of the theoretical ABC+f(n) model with experimental data shows that a good fit requires the inclusion of the f(n) term.

Dai, Qi; Shan, Qifeng; Wang, Jing; Chhajed, Sameer; Cho, Jaehee; Schubert, E. Fred; Crawford, Mary H.; Koleske, Daniel D.; Kim, Min-Ho; Park, Yongjo

2010-01-01T23:59:59.000Z

19

Green (In,Ga,Al)P-GaP light-emitting diodes grown on high-index GaAs surfaces  

SciTech Connect (OSTI)

We report on green (550–560?nm) electroluminescence (EL) from (Al{sub 0.5}Ga{sub 0.5}){sub 0.5}In{sub 0.5}P-(Al{sub 0.8}Ga{sub 0.2}){sub 0.5}In{sub 0.5}P double p-i-n heterostructures with monolayer-scale GaP insertions in the cladding layers and light-emitting diodes based thereupon. The structures are grown side-by-side on high-index and (100) GaAs substrates by molecular beam epitaxy. At moderate current densities (?500?A/cm{sup 2}), the EL intensity of the structures is comparable for all substrate orientations. Opposite to the (100)-grown strictures, the EL spectra of (211) and (311)-grown devices are shifted towards shorter wavelengths (?550?nm at room temperature). At high current densities (>1?kA/cm{sup 2}), a much higher EL intensity is achieved for the devices grown on high-index substrates. The integrated intensity of (311)-grown structures gradually saturates at current densities above 4?kA/cm{sup 2}, whereas no saturation is revealed for (211)-grown structures up to the current densities above 14?kA/cm{sup 2}. We attribute the effect to the surface orientation-dependent engineering of the GaP band structure, which prevents the escape of the nonequilibrium electrons into the indirect conduction band minima of the p-doped (Al{sub 0.8}Ga{sub 0.2}){sub 0.5}In{sub 0.5}P cladding layers.

Ledentsov, N. N., E-mail: nikolay.ledentsov@v-i-systems.com; Shchukin, V. A. [VI Systems GmbH, Hardenbergstr. 7, Berlin D-10623 (Germany); Lyytikäinen, J.; Okhotnikov, O. [Optoelectronics Research Centre, Tampere University of Technology, Tampere FI-33720 (Finland); Shernyakov, Yu. M.; Payusov, A. S.; Gordeev, N. Yu.; Maximov, M. V. [A. F. Ioffe Physical Technical Institute of the Russian Academy of Sciences, Politekhnicheskaya 26, St. Petersburg 194021 (Russian Federation); Schlichting, S.; Nippert, F.; Hoffmann, A. [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, Berlin D-10623 (Germany)

2014-11-03T23:59:59.000Z

20

Tunnel-injection GaN quantum dot ultraviolet light-emitting diodes  

SciTech Connect (OSTI)

We demonstrate a GaN quantum dot ultraviolet light-emitting diode that uses tunnel injection of carriers through AlN barriers into the active region. The quantum dot heterostructure is grown by molecular beam epitaxy on AlN templates. The large lattice mismatch between GaN and AlN favors the formation of GaN quantum dots in the Stranski-Krastanov growth mode. Carrier injection by tunneling can mitigate losses incurred in hot-carrier injection in light emitting heterostructures. To achieve tunnel injection, relatively low composition AlGaN is used for n- and p-type layers to simultaneously take advantage of effective band alignment and efficient doping. The small height of the quantum dots results in short-wavelength emission and are simultaneously an effective tool to fight the reduction of oscillator strength from quantum-confined Stark effect due to polarization fields. The strong quantum confinement results in room-temperature electroluminescence peaks at 261 and 340 nm, well above the 365 nm bandgap of bulk GaN. The demonstration opens the doorway to exploit many varied features of quantum dot physics to realize high-efficiency short-wavelength light sources.

Verma, Jai; Kandaswamy, Prem Kumar; Protasenko, Vladimir; Verma, Amit; Grace Xing, Huili; Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)] [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)

2013-01-28T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

The use of short-period InGaN/GaN superlattices in blue-region light-emitting diodes  

SciTech Connect (OSTI)

Optical and light-emitting diode structures with an active InGaN region containing short-period InGaN/GaN superlattices are studied. It is shown that short-period superlattices are thin two-dimensional layers with a relatively low In content that contain inclusions with a high In content 1-3 nm thick. Inclusions manifest themselves from the point of view of optical properties as a nonuniform array of quantum dots involved in a residual quantum well. The use of short-period superlattices in light-emitting diode structures allows one to decrease the concentration of nonradiative centers, as well as to increase the injection of carriers in the active region due to an increase in the effective height of the AlGaN barrier, which in general leads to an increase in the quantum efficiency of light-emitting diodes.

Sizov, V. S., E-mail: vsizov@mail.ioffe.ru; Tsatsulnikov, A. F.; Sakharov, A. V.; Lundin, W. V.; Zavarin, E. E.; Cherkashin, N. A. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Hytch, M. J. [National Center for Scientific Research (CNRS), Center for Material Elaboration and Structural Studies (CEMES) (France); Nikolaev, A. E. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Mintairov, A. M.; He Yan; Merz, J. L. [University of Notre Dame, EE Department (United States)

2010-07-15T23:59:59.000Z

22

Remarkably reduced efficiency droop by using staircase thin InGaN quantum barriers in InGaN based blue light emitting diodes  

SciTech Connect (OSTI)

The efficiency droop of InGaN/GaN(InGaN) multiple quantum well (MQW) light emitting diodes (LEDs) with thin quantum barriers (QB) is studied. With thin GaN QB (3?nm–6?nm thickness), the efficiency droop is not improved, which indicates that hole transport cannot be significantly enhanced by the thin GaN QBs. On the contrary, the efficiency droop was remarkably reduced by using a InGaN staircase QB (InGaN SC-QB) MQWs structure where InGaN SC-QBs lower the transport energy barrier of holes. The efficiency droop ratio was as low as 3.3% up to 200?A/cm{sup 2} for the InGaN SC-QB LED. By using monitoring QW with longer wavelength we observe a much uniform carrier distribution in the InGaN SC-QB LEDs, which reveals the mechanism of improvement in the efficiency droop.

Zhou, Kun; Ikeda, Masao, E-mail: mikeda2013@sinano.ac.cn, E-mail: jpliu2010@sinano.ac.cn; Liu, Jianping, E-mail: mikeda2013@sinano.ac.cn, E-mail: jpliu2010@sinano.ac.cn; Zhang, Shuming; Li, Deyao; Zhang, Liqun; Yang, Hui [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou (China); Key Laboratory of Nanodevices and Applications, Chinese Academy of Sciences, Suzhou (China); Cai, Jin; Wang, Hui; Wang, H. B. [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou (China); Key Laboratory of Nanodevices and Applications, Chinese Academy of Sciences, Suzhou (China); Suzhou Nanojoin Photonics Co., Ltd., Suzhou (China)

2014-10-27T23:59:59.000Z

23

Strong light-matter coupling in ultrathin double dielectric mirror GaN microcavities  

SciTech Connect (OSTI)

Strong light-matter coupling is demonstrated at low temperature in an ultrathin GaN microcavity fabricated using two silica/zirconia Bragg mirrors, in addition to a three-period epitaxial (Al,Ga)N mirror serving as an etch stop and assuring good quality of the overgrown GaN. The {lambda}/2 cavity is grown by molecular beam epitaxy on a Si substrate. Analysis of angle-resolved data reveal key features of the strong coupling regime in both reflectivity and transmission spectra at 5 K: anticrossing with a normal mode splitting of 43{+-}2 meV and 56{+-}2 meV for reflectivity and transmission, respectively, and narrowing of the lower polariton linewidth near resonance.

Bejtka, K.; Martin, R. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); CRHEA-CNRS, Rue Bernard Gregory, Parc Sophia Antipolis, 06560 Valbonne (France); Reveret, F.; Vasson, A.; Leymarie, J. [LASMEA, UMR 6602 UBP/CNRS, 24 Avenue des Landais, F-63177 Aubiere Cedex (France); Edwards, P. R. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Sellers, I. R.; Duboz, J. Y.; Leroux, M.; Semond, F. [CRHEA-CNRS, Rue Bernard Gregory, Parc Sophia Antipolis, 06560 Valbonne (France)

2008-06-16T23:59:59.000Z

24

Stress-induced piezoelectric field in GaN-based 450-nm light-emitting diodes  

SciTech Connect (OSTI)

We investigated the influence of the built-in piezoelectric field induced by compressive stress on the characteristics of GaN-based 450-nm light-emitting diodes (LEDs) prepared on sapphire substrates of different thicknesses. As the sapphire substrate thickness was reduced, the compressive stress in the GaN layer was released, resulting in wafer bowing. The wafer bowing-induced mechanical stress altered the piezoelectric field, which in turn reduced the quantum confined Stark effect in the InGaN/GaN active region of the LED. The flat-band voltage was estimated by measuring the applied bias voltage that induced a 180° phase shift in the electro-reflectance (ER) spectrum. The piezoelectric field estimated by the ER spectra changed by ?110?kV/cm. The electroluminescence spectral peak wavelength was blue-shifted, and the internal quantum efficiency was improved by about 22% at a high injection current of 100?mA. The LED on the 60-?m-thick sapphire substrate exhibited the highest light output power of ?59?mW at an injection current of 100?mA, with the operating voltage unchanged.

Tawfik, Wael Z. [Department of Materials Science and Engineering, Chonnam National University, Yongbong 300 Gwangju 500-757 (Korea, Republic of); Department of Physics, Faculty of Science, Beni-Suef University, Beni-Suef 62511 (Egypt); Hyeon, Gil Yong; Lee, June Key, E-mail: junekey@chonnam.ac.kr [Department of Materials Science and Engineering, Chonnam National University, Yongbong 300 Gwangju 500-757 (Korea, Republic of)

2014-10-28T23:59:59.000Z

25

Polarization engineering via staggered InGaN quantum wells for radiative efficiency enhancement of light emitting diodes  

E-Print Network [OSTI]

of light emitting diodes Ronald A. Arif, Yik-Khoon Ee, and Nelson Tansu Citation: Appl. Phys. Lett. 91 extraction in GaN-based light emitting diodes Appl. Phys. Lett. 100, 061107 (2012) Electrically driven nanopyramid green light emitting diode Appl. Phys. Lett. 100, 061106 (2012) Ultraviolet electroluminescence

Gilchrist, James F.

26

Origin of InGaN/GaN light-emitting diode efficiency improvements using tunnel-junction-cascaded active regions  

SciTech Connect (OSTI)

This Letter investigates the efficiency enhancement achieved by tunnel junction insertion into the InGaN/GaN multi-quantum well (MQW) active region of blue light emitting diodes (LEDs). The peak quantum efficiency of such LED exceeds 100%, but the maximum wall-plug efficiency (WPE) hardly changes. However, due to the increased bias, the WPE peaks at much higher input power, i.e., the WPE droop is significantly delayed, and the output power is strongly enhanced. The main physical reason for this improvement lies in the non-uniform vertical carrier distribution typically observed within InGaN MQWs.

Piprek, Joachim, E-mail: piprek@nusod.org [NUSOD Institute LLC, P.O. Box 7204, Newark, Delaware 19714 (United States)

2014-02-03T23:59:59.000Z

27

Organic Light Emitting Diodes Using a Ga:ZnO Anode  

SciTech Connect (OSTI)

We report the application of gallium doped zinc oxide (GZO) films as anodes in organic light emitting diodes (OLEDs). Pulsed laser deposited GZO films of differing Ga composition are examined. Bilayer OLEDs using GZO and indium tin oxide (ITO) anodes are then compared. Relative to ITO, the GZO anodes have slightly better sheet resistance and transparency in the visible spectral region. Device data suggest GZO results in more effective hole injection into an aromatic triamine hole transporting layer. Indium free anodes are expected toimprove OLED stability while lowering the cost per unit area, crucial for OLED based lighting applications.

Berry, J. J.; Ginley, D. S.; Burrows, Paul E.

2008-05-12T23:59:59.000Z

28

Growths of staggered InGaN quantum wells light-emitting diodes emitting at 520525 nm employing graded growth-temperature profile  

E-Print Network [OSTI]

Growths of staggered InGaN quantum wells light-emitting diodes emitting at 520­525 nm employing current spreading and light extraction in GaN-based light emitting diodes Appl. Phys. Lett. 100, 061107 (2012) Electrically driven nanopyramid green light emitting diode Appl. Phys. Lett. 100, 061106 (2012

Gilchrist, James F.

29

Measurement of the absorption coefficient for light laterally propagating in light-emitting diode structures with In{sub 0.2}Ga{sub 0.8}N/GaN quantum wells  

SciTech Connect (OSTI)

A procedure for measuring the absorption coefficient for light propagating parallel to the surface of a GaN-based light emitting diode chip on a sapphire substrate is suggested. The procedure implies the study of emission from one end face of the chip as the opposite end face is illuminated with a light emitting diode. The absorption coefficient is calculated from the ratio between the intensities of emission emerging from the end faces of the sapphire substrate and the epitaxial layer. From the measurements for chips based on p-GaN/In{sub 0.2}Ga{sub 0.8}N/n-GaN structures, the lateral absorption coefficient is determined at a level of (23 {+-} 3)cm{sup -1} at a wavelength of 465 nm. Possible causes for the discrepancy between the absorption coefficients determined in the study and those reported previously are analyzed.

Lelikov, Yu. S.; Bochkareva, N. I.; Gorbunov, R. I.; Martynov, I. A.; Rebane, Yu. T.; Tarkin, D. V.; Shreter, Yu. G. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)], E-mail: YShreter@mail.ioffe.ru

2008-11-15T23:59:59.000Z

30

White light generation by resonant nonradiative energy transfer from epitaxial InGaN/GaN quantum wells to colloidal CdSe/ZnS core/shell quantum dots  

E-Print Network [OSTI]

White light generation by resonant nonradiative energy transfer from epitaxial InGaN/GaN quantum n a l f o r p h y s i c s New Journal of Physics White light generation by resonant nonradiative white-light-generating nonradiative energy transfer (ET) from epitaxial quantum wells (QWs) to colloidal

Demir, Hilmi Volkan

31

Comparative study of field-dependent carrier dynamics and emission kinetics of InGaN/GaN light-emitting diodes grown on (11 2 2) semipolar versus (0001) polar  

E-Print Network [OSTI]

Articles you may be interested in Ultraviolet light-emitting diodes grown by plasma-assisted molecular beam light-emitting diodes prepared on ( 11 2 ¯ 2 ) -plane GaN J. Appl. Phys. 100, 113109 (2006); 10.1063/1.2382667 Demonstration of a semipolar ( 10 1 ¯ 3 ¯ ) In Ga N Ga N green light emitting diode Appl. Phys. Lett. 87, 231110

Demir, Hilmi Volkan

32

Broadband visible light source based on AllnGaN light emitting diodes  

DOE Patents [OSTI]

A visible light source device is described based on a light emitting diode and a nanocluster-based film. The light emitting diode utilizes a semiconductor quantum well structure between n-type and p-type semiconductor materials on the top surface a substrate such as sapphire. The nanocluster-based film is deposited on the bottom surface of the substrate and can be derived from a solution of MoS.sub.2, MoSe.sub.2, WS.sub.2, and WSe.sub.2 particles of size greater than approximately 2 nm in diameter and less than approximately 15 nm in diameter, having an absorption wavelength greater than approximately 300 nm and less than approximately 650 nm.

Crawford, Mary H.; Nelson, Jeffrey S.

2003-12-16T23:59:59.000Z

33

Temperature-dependent efficiency droop of blue InGaN micro-light emitting diodes  

SciTech Connect (OSTI)

Temperature-dependent trends in radiative and Auger recombination coefficients have been determined at different injection carrier concentrations using InGaN micro-light emitting diodes 40 ?m in diameter. The differential lifetime was obtained first from the measured modulation bandwidth and was then employed to calculate the carrier concentration in the quantum well active region. When the temperature increases, the carrier concentration increases, but both the radiative and Auger recombination coefficients decrease. In addition, the temperature dependence of radiative and Auger recombination coefficients is weaker at a higher injection carrier concentration, which is strongly related to phase space filling.

Tian, Pengfei; McKendry, Jonathan J. D.; Herrnsdorf, Johannes; Ferreira, Ricardo; Watson, Ian M.; Gu, Erdan, E-mail: erdan.gu@strath.ac.uk; Dawson, Martin D. [Institute of Photonics, University of Strathclyde, 106 Rottenrow, Glasgow G4 0NW (United Kingdom); Watson, Scott; Kelly, Anthony E. [School of Engineering, University of Glasgow, James Watt South Building, Glasgow G12 8LT (United Kingdom)

2014-10-27T23:59:59.000Z

34

Internal efficiency of InGaN light-emitting diodes: Beyond a quasiequilibrium model  

SciTech Connect (OSTI)

We propose a model to better investigate InGaN light-emitting diode (LED) internal efficiency by extending beyond the usual total carrier density rate equation approach. To illustrate its capability, the model is applied to study intrinsic performance differences between violet and green LEDs. The simulations show performance differences, at different current densities and temperatures, arising from variations in spontaneous emission and heat loss rates. By tracking the momentum-resolved carrier populations, these rate changes are, in turn, traced to differences in bandstructure and plasma heating. The latter leads to carrier distributions that deviate from the quasiequilibrium ones at lattice temperature.

Chow, Weng W.; Crawford, Mary H.; Tsao, Jeffrey Y.; Kneissl, Michael

2010-01-01T23:59:59.000Z

35

Growth and characterizations of GaN micro-rods on graphene films for flexible light emitting diodes  

SciTech Connect (OSTI)

We report the growth of GaN micro-rods and coaxial quantum-well heterostructures on graphene films, together with structural and optical characterization, for applications in flexible optical devices. Graphene films were grown on Cu foil by means of chemical vapor deposition, and used as the substrates for the growth of the GaN micro-rods, which were subsequently transferred onto SiO{sub 2}/Si substrates. Highly Si-doped, n-type GaN micro-rods were grown on the graphene films using metal–organic chemical vapor deposition. The growth and vertical alignment of the GaN micro-rods, which is a critical factor for the fabrication of high-performance light-emitting diodes (LEDs), were characterized using electron microscopy and X-ray diffraction. The GaN micro-rods exhibited promising photoluminescence characteristics for optoelectronic device applications, including room-temperature stimulated emission. To fabricate flexible LEDs, In{sub x}Ga{sub 1–x}N/GaN multiple quantum wells and a p-type GaN layer were deposited coaxially on the GaN micro-rods, and transferred onto Ag-coated polymer substrates using lift-off. Ti/Au and Ni/Au metal layers were formed to provide electrical contacts to the n-type and p-type GaN regions, respectively. The micro-rod LEDs exhibited intense emission of visible light, even after transfer onto the flexible polymer substrate, and reliable operation was achieved following numerous cycles of mechanical deformation.

Chung, Kunook; Beak, Hyeonjun; Tchoe, Youngbin; Oh, Hongseok; Yi, Gyu-Chul, E-mail: gcyi@snu.ac.kr [Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 151-747 (Korea, Republic of); Yoo, Hyobin; Kim, Miyoung [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

2014-09-01T23:59:59.000Z

36

GaN nanorod light emitting diodes with suspended graphene transparent electrodes grown by rapid chemical vapor deposition  

SciTech Connect (OSTI)

Ordered and dense GaN light emitting nanorods are studied with polycrystalline graphene grown by rapid chemical vapor deposition as suspended transparent electrodes. As the substitute of indium tin oxide, the graphene avoids complex processing to fill up the gaps between nanorods and subsequent surface flattening and offers high conductivity to improve the carrier injection. The as-fabricated devices have 32% improvement in light output power compared to conventional planar GaN-graphene diodes. The suspended graphene remains electrically stable up to 300?°C in air. The graphene can be obtained at low cost and high efficiency, indicating its high potential in future applications.

Xu, Kun; Xu, Chen, E-mail: xuchen58@bjut.edu.cn; Deng, Jun; Zhu, Yanxu; Guo, Weiling; Mao, Mingming; Xun, Meng; Chen, Maoxing; Zheng, Lei [Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing 100124 (China)] [Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing 100124 (China); Xie, Yiyang [State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductor, Chinese Academy of Sciences, Beijing 100083 (China)] [State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductor, Chinese Academy of Sciences, Beijing 100083 (China); Sun, Jie, E-mail: jie.sun@chalmers.se [Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing 100124 (China) [Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing 100124 (China); Mikroteknologi och Nanovetenskap, Chalmers Tekniska Högskola AB, Göteborg 41296 (Sweden)

2013-11-25T23:59:59.000Z

37

Tailoring broadband light trapping of GaAs and Si substrates by self-organised nanopatterning  

SciTech Connect (OSTI)

We report on the formation of high aspect ratio anisotropic nanopatterns on crystalline GaAs (100) and Si (100) substrates exploiting defocused Ion Beam Sputtering assisted by a sacrificial self-organised Au stencil mask. The tailored optical properties of the substrates are characterised in terms of total reflectivity and haze by means of integrating sphere measurements as a function of the morphological modification at increasing ion fluence. Refractive index grading from sub-wavelength surface features induces polarisation dependent anti-reflection behaviour in the visible-near infrared (VIS-NIR) range, while light scattering at off-specular angles from larger structures leads to very high values of the haze functions in reflection. The results, obtained for an important class of technologically relevant materials, are appealing in view of photovoltaic and photonic applications aiming at photon harvesting in ultrathin crystalline solar cells.

Martella, C.; Chiappe, D.; Mennucci, C.; Buatier de Mongeot, F. [Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, I-16146 Genova (Italy)

2014-05-21T23:59:59.000Z

38

Direct Water Splitting under Visible Light with a Nanostructured Photoanode and GaInP2 Photocathode  

SciTech Connect (OSTI)

Thin films of hematite nanorod and GaInP2 were used for direct water splitting under visible light. In open circuit conditions, the potential of hematite shifted cathodically and that of GaInP2 anodically, which generated an open circuit voltage between the two electrodes. In short circuit condition, the combination of the two photoelectrodes can split water under visible light illumination, though with a very low current of {micro}A/cm2 level even at 1 W/cm2 light. By means of chopped light, we found that hematite nanorod has a low photocurrent, which is responsible for the low short circuit current of the 2-electrode combination. The low photoresponse of hematite nanorods is due to the recombination of photo- generated charges, low holes mobility, and short diffusion length.

Wang, H.; Deutsch, T.; Turner, J.

2008-01-01T23:59:59.000Z

39

High-temperature luminescence in an n-GaSb/n-InGaAsSb/p-AlGaAsSb light-emitting heterostructure with a high potential barrier  

SciTech Connect (OSTI)

The electroluminescent properties of an n-GaSb/n-InGaAsSb/p-AlGaAsSb heterostructure with a high potential barrier in the conduction band (large conduction-band offset) at the n-GaSb/n-InGaAsSb type-II heterointerface ({Delta}E{sub c} = 0.79 eV) are studied. Two bands with peaks at 0.28 and 0.64 eV at 300 K, associated with radiative recombination in n-InGaAsSb and n-GaSb, respectively, are observed in the electroluminescence (EL) spectrum. In the entire temperature range under study, T = 290-480 K, additional electron-hole pairs are formed in the n-InGaAsSb active region by impact ionization with hot electrons heated as a result of the conduction-band offset. These pairs contribute to radiative recombination, which leads to a nonlinear increase in the EL intensity and output optical power with increasing pump current. A superlinear increase in the emission power of the long-wavelength band is observed upon heating in the temperature range T = 290-345 K, and a linear increase is observed at T > 345 K. This work for the first time reports an increase in the emission power of a light-emitting diode structure with increasing temperature. It is shown that this rise is caused by a decrease in the threshold energy of the impact ionization due to narrowing of the band gap of the active region.

Petukhov, A. A., E-mail: andrey-rus29@rambler.ru; Zhurtanov, B. E.; Kalinina, K. V.; Stoyanov, N. D.; Salikhov, H. M.; Mikhailova, M. P.; Yakovlev, Yu. P. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

2013-09-15T23:59:59.000Z

40

Angular distribution of polarized spontaneous emissions and its effect on light extraction behavior in InGaN-based light emitting diodes  

SciTech Connect (OSTI)

Angular intensity distributions of differently polarized light sources in multiple quantum wells (MQWs) and their effects on extraction behavior of spontaneous emission from light emitting diode (LED) chips have been studied. Theoretical calculation based on k·p approximation, ray tracing simulation and angular electroluminescence measurement were applied in this work. It is found that the electron-hole recombination in the InGaN MQWs produces a spherical distribution of an s-polarized source and a dumbbell-shaped p-polarized source. Light rays from different polarized sources experience different extraction processes, determining the polarization degree of electro-luminescence and extraction efficiency of LEDs.

Yuan, Gangcheng; Chen, Xinjuan; Yu, Tongjun, E-mail: tongjun@pku.edu.cn; Lu, Huimin; Chen, Zhizhong; Kang, Xiangning; Wu, Jiejun; Zhang, Guoyi [State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China)

2014-03-07T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
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41

Experimental verification of effects of barrier dopings on the internal electric fields and the band structure in InGaN/GaN light emitting diodes  

SciTech Connect (OSTI)

We experimentally clarify the effects of barrier dopings on the polarization induced electric fields and the band structure in InGaN/GaN blue light emitting diodes. Both effects were independently verified by using electric field modulated reflectance and capacitance-voltage measurement. It is shown that the Si barrier doping does reduce the polarization induced electric field in the quantum wells. But the benefit of Si-doping is nullified by modification of the band structure and depletion process. With increased number of doped barriers, smaller number of quantum wells remains in the depletion region at the onset of the diffusion process, which can reduce the effective active volume and enhance the electron overflow.

Song, Jung-Hoon; Kim, Tae-Soo; Park, Ki-Nam; Lee, Jin-Gyu [Department of Physics, Kongju National University, Kongju, Chungnam 314-701 (Korea, Republic of); Hong, Soon-Ku, E-mail: soonku@cnu.ac.kr [Department of Advanced Materials Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Cho, Sung-Royng; Lee, Seogwoo; Whan Cho, Meoung [Wasvesquare Co., Inc., Yongin, Gyeonggi 449-863 (Korea, Republic of)

2014-03-24T23:59:59.000Z

42

Direct periodic patterning of GaN-based light-emitting diodes by three-beam interference laser ablation  

SciTech Connect (OSTI)

We report on the direct patterning of two-dimensional periodic structures in GaN-based light-emitting diodes (LEDs) through laser interference ablation for the fast and reliable fabrication of periodic micro- and nano-structures aimed at enhancing light output. Holes arranged in a two-dimensional hexagonal lattice array having an opening size of 500?nm, depth of 50?nm, and a periodicity of 1??m were directly formed by three-beam laser interference without photolithography or electron-beam lithography processes. The laser-patterned LEDs exhibit an enhancement in light output power of 20% compared to conventional LEDs having a flat top surface without degradation of electrical and optical properties of the top p-GaN layer and the active region, respectively.

Kim, Jeomoh; Ji, Mi-Hee; Detchprohm, Theeradetch [Center for Compound Semiconductors and School of Electrical and Computer Engineering, Georgia Institute of Technology, 777 Atlantic Dr. NW, Atlanta, Georgia 30332-0250 (United States); Yuan, Dajun; Guo, Rui [Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); Liu, Jianping [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou, Jiangsu 215125 (China); Asadirad, Mojtaba [Materials Engineering Program, University of Houston, Houston, Texas 77204-4005 (United States); Kwon, Min-Ki [Department of Photonic Engineering, Chosun University, Seosuk-dong, Gwangju 501-759 (Korea, Republic of); Dupuis, Russell D. [Center for Compound Semiconductors and School of Electrical and Computer Engineering, Georgia Institute of Technology, 777 Atlantic Dr. NW, Atlanta, Georgia 30332-0250 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Das, Suman [Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Ryou, Jae-Hyun, E-mail: jryou@uh.edu [Materials Engineering Program, University of Houston, Houston, Texas 77204-4005 (United States); Department of Mechanical Engineering and Texas Center for Superconductivity at the University of Houston (TcSUH), University of Houston, Houston, Texas 77204-4006 (United States)

2014-04-07T23:59:59.000Z

43

Light-extraction enhancement in GaN-based light-emitting diodes using grade-refractive-index amorphous titanium oxide films with porous structures  

SciTech Connect (OSTI)

Amorphous titanium oxide (a-TiO{sub x}:OH) films prepared by plasma-enhanced chemical-vapor deposition at 200 and 25 deg. C are in turn deposited onto the GaN-based light-emitting diode (LED) to enhance the associated light extraction efficiency. The refractive index, porosity, and photocatalytic effect of the deposited films are correlated strongly with the deposition temperatures. The efficiency is enhanced by a factor of {approx}1.31 over that of the uncoated LEDs and exhibited an excellent photocatalytic property after an external UV light irradiation. The increase in the light extraction is related to the reduction in the Fresnel transmission loss and the enhancement of the light scattering into the escape cone by using the graded-refractive-index a-TiO{sub x}:OH film with porous structures.

Liu, D.-S.; Lin, T.-W.; Huang, B.-W.; Juang, F.-S.; Lei, P.-H. [Institute of Electro-Optical and Materials Science, National Formosa University, Huwei 63201, Taiwan (China); Hu, C.-Z. [Chilin Technology Co. Ltd., Tainan County 71758, Taiwan (China)

2009-04-06T23:59:59.000Z

44

Modulating emission intensity of GaN-based green light emitting diodes on c-plane sapphire  

SciTech Connect (OSTI)

The asymmetric dual-wavelength (green/blue) coupled InGaN/GaN multiple quantum wells were proposed to modulate the green emission intensity. Electroluminescent measurements demonstrate the conspicuous increment of the green light intensity by decreasing the coupled barrier thickness. This was partly attributed to capture of more carriers when holes tunnel across the thinner barrier from the blue quantum wells, as a hole reservoir, to the green quantum wells. While lower effective barrier height of the blue quantum wells benefits improved hole transportation from p-GaN to the active region. Efficiency droop of the green quantum wells was partially alleviated due to the enhanced injection efficiency of holes.

Du, Chunhua; Ma, Ziguang; Zhou, Junming; Lu, Taiping; Jiang, Yang; Jia, Haiqiang; Liu, Wuming; Chen, Hong, E-mail: hchen@iphy.ac.cn [Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condense Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2014-04-14T23:59:59.000Z

45

The impact of trench defects in InGaN/GaN light emitting diodes and implications for the “green gap” problem  

SciTech Connect (OSTI)

The impact of trench defects in blue InGaN/GaN light emitting diodes (LEDs) has been investigated. Two mechanisms responsible for the structural degradation of the multiple quantum well (MQW) active region were identified. It was found that during the growth of the p-type GaN capping layer, loss of part of the active region enclosed within a trench defect occurred, affecting the top-most QWs in the MQW stack. Indium platelets and voids were also found to form preferentially at the bottom of the MQW stack. The presence of high densities of trench defects in the LEDs was found to relate to a significant reduction in photoluminescence and electroluminescence emission efficiency, for a range of excitation power densities and drive currents. This reduction in emission efficiency was attributed to an increase in the density of non-radiative recombination centres within the MQW stack, believed to be associated with the stacking mismatch boundaries which form part of the sub-surface structure of the trench defects. Investigation of the surface of green-emitting QW structures found a two decade increase in the density of trench defects, compared to its blue-emitting counterpart, suggesting that the efficiency of green-emitting LEDs may be strongly affected by the presence of these defects. Our results are therefore consistent with a model that the “green gap” problem might relate to localized strain relaxation occurring through defects.

Massabuau, F. C.-P., E-mail: fm350@cam.ac.uk; Oehler, F.; Pamenter, S. K.; Thrush, E. J.; Kappers, M. J.; Humphreys, C. J.; Oliver, R. A. [Department of Materials Science and Metallurgy, University of Cambridge, 22 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Davies, M. J.; Dawson, P. [Photon Science Institute, School of Physics and Astronomy, Alan Turing Building, University of Manchester, Manchester M13 9PL (United Kingdom); Kovács, A.; Dunin-Borkowski, R. E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, Leo-Brandt- Straße, D-52425 Jülich (Germany); Williams, T.; Etheridge, J. [Monash Centre for Electron Microscopy, Monash University, Clayton Campus, VIC 3800 (Australia); Hopkins, M. A.; Allsopp, D. W. E. [Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY (United Kingdom)

2014-09-15T23:59:59.000Z

46

Strong light-matter coupling in bulk GaN-microcavities with double dielectric mirrors fabricated by two different methods  

SciTech Connect (OSTI)

Two routes for the fabrication of bulk GaN microcavities embedded between two dielectric mirrors are described, and the optical properties of the microcavities thus obtained are compared. In both cases, the GaN active layer is grown by molecular beam epitaxy on (111) Si, allowing use of selective etching to remove the substrate. In the first case, a three period Al{sub 0.2}Ga{sub 0.8}N/AlN Bragg mirror followed by a {lambda}/2 GaN cavity are grown directly on the Si. In the second case, a crack-free 2 {mu}m thick GaN layer is grown, and progressively thinned to a final thickness of {lambda}. Both devices work in the strong coupling regime at low temperature, as evidenced by angle-dependent reflectivity or transmission experiments. However, strong light-matter coupling in emission at room temperature is observed only for the second one. This is related to the poor optoelectronic quality of the active layer of the first device, due to its growth only 250 nm above the Si substrate and its related high defect density. The reflectivity spectra of the microcavities are well accounted for by using transfer matrix calculations.

Reveret, F.; Disseix, P.; Vasson, A.; Leymarie, J. [Clermont Universite, Universite Blaise Pascal, LASMEA, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6602, LASMEA, F-63177 Aubiere (France); Bejtka, K. [CRHEA-CNRS, Rue Bernard Gregory, Parc Sophia Antipolis, 06560 Valbonne (France); Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Edwards, P. R.; Martin, R. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Chenot, S.; Sellers, I. R.; Duboz, J. Y.; Leroux, M.; Semond, F. [CRHEA-CNRS, Rue Bernard Gregory, Parc Sophia Antipolis, 06560 Valbonne (France)

2010-08-15T23:59:59.000Z

47

Milliwatt operation of AlGaN-based single-quantum-well light emitting diode in the ultraviolet region  

SciTech Connect (OSTI)

By introducing a single-quantum-well active layer and a high-Al-content carrier blocking layer, the output power of an AlGaN-based ultraviolet light-emitting diode has been improved by one order of magnitude. Optical output of 1 mW was achieved at the emission peak wavelength of 341{endash}343 nm. {copyright} 2001 American Institute of Physics.

Nishida, Toshio; Saito, Hisao; Kobayashi, Naoki

2001-06-18T23:59:59.000Z

48

Impact of heavy hole-light hole coupling on optical selection rules in GaAs quantum dots  

SciTech Connect (OSTI)

We report strong heavy hole-light hole mixing in GaAs quantum dots grown by droplet epitaxy. Using the neutral and charged exciton emission as a monitor we observe the direct consequence of quantum dot symmetry reduction in this strain free system. By fitting the polar diagram of the emission with simple analytical expressions obtained from k{center_dot}p theory we are able to extract the mixing that arises from the heavy-light hole coupling due to the geometrical asymmetry of the quantum dot.

Belhadj, T.; Amand, T.; Kunz, S.; Marie, X.; Urbaszek, B. [INSA-CNRS-UPS, LPCNO, Universite de Toulouse, 135 Av. Rangueil, 31077 Toulouse (France); Kunold, A. [INSA-CNRS-UPS, LPCNO, Universite de Toulouse, 135 Av. Rangueil, 31077 Toulouse (France); Departamento de Ciencias Basicas, UAM-A, Col. Reynosa Tamaulipas, 02200 Mexico D.F. (Mexico); Simon, C.-M. [INSA-CNRS-UPS, LPCNO, Universite de Toulouse, 135 Av. Rangueil, 31077 Toulouse (France); CNRS-UPS, LCAR, IRSAMC, Universite de Toulouse, 31062 Toulouse (France); Kuroda, T.; Abbarchi, M.; Mano, T.; Sakoda, K. [National Institute for Material Science, Namiki 1-1, Tsukuba 305-0044 (Japan)

2010-08-02T23:59:59.000Z

49

Energy distribution of nonequilibrium electrons and optical phonons in GaAs under band-to-band pumping by intense short pulses of light  

SciTech Connect (OSTI)

Deviation from the Fermi distribution of nonequilibrium electrons and distribution of 'hot' optical phonons in GaAs under band-to-band pumping by picosecond pulses of light are calculated.

Altybaev, G. S.; Kumekov, S. E., E-mail: skumekov@mail.ru; Mahmudov, A. A. [Satpaev Kazakh National Technical University (Kazakhstan)

2009-03-15T23:59:59.000Z

50

Comm'ea'o.n Energy Conservation  

E-Print Network [OSTI]

t f i CaUforn'. Enel'" Comm'ea'o.n Energy Conservation Standards for New Residential Buildings E;#12;CALIFORNIA ADMINISTRATIVE CODE Title 20 Chapter 2 (California Energy Commission) Subchap ter 4 (Conservation

51

Inversion by metalorganic chemical vapor deposition from N- to Ga-polar gallium nitride and its application to multiple quantum well light-emitting diodes  

SciTech Connect (OSTI)

We demonstrate a metalorganic chemical vapor deposition growth approach for inverting N-polar to Ga-polar GaN by using a thin inversion layer grown with high Mg flux. The introduction of this inversion layer allowed us to grow p-GaN films on N-polar GaN thin film. We have studied the dependence of hole concentration, surface morphology, and degree of polarity inversion for the inverted Ga-polar surface on the thickness of the inversion layer. We then use this approach to grow a light emitting diode structure which has the MQW active region grown on the advantageous N-polar surface and the p-layer grown on the inverted Ga-polar surface.

Hosalli, A. M.; Van Den Broeck, D. M.; Bedair, S. M. [Department of Electrical and Computer Engineering, NCSU, Raleigh, North Carolina 27695 (United States)] [Department of Electrical and Computer Engineering, NCSU, Raleigh, North Carolina 27695 (United States); Bharrat, D.; El-Masry, N. A. [Department of Material Science and Engineering, NCSU, Raleigh, North Carolina 27695 (United States)] [Department of Material Science and Engineering, NCSU, Raleigh, North Carolina 27695 (United States)

2013-12-02T23:59:59.000Z

52

MOCVD growth of In GaP-based heterostructures for light emitting devices  

E-Print Network [OSTI]

In this work, we examine fundamental materials processes in the growth of indium gallium phosphide (InGaP) via metalorganic chemical vapor deposition (MOCVD). In particular, we realize improvements in the epitaxial integration ...

McGill, Lisa Megan, 1975-

2004-01-01T23:59:59.000Z

53

Analysis of different tunneling mechanisms of In{sub x}Ga{sub 1?x}As/AlGaAs tunnel junction light-emitting transistors  

SciTech Connect (OSTI)

The electrical and optical characteristics of tunnel junction light-emitting transistors (TJLETs) with different indium mole fractions (x?=?5% and 2.5%) of the In{sub x}Ga{sub 1?x}As base-collector tunnel junctions have been investigated. Two electron tunneling mechanisms (photon-assisted or direct tunneling) provide additional currents to electrical output and resupply holes back to the base region, resulting in the upward slope of I-V curves and enhanced optical output under forward-active operation. The larger direct tunneling probability and stronger Franz-Keldysh absorption for 5% TJLET lead to higher collector current slope and less optical intensity enhancement when base-collector junction is under reverse-biased.

Wu, Cheng-Han [Graduate Institute of Electronics Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan (China); Wu, Chao-Hsin, E-mail: chaohsinwu@ntu.edu.tw [Graduate Institute of Electronics Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan (China); Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan (China)

2014-10-27T23:59:59.000Z

54

Enhancing the quantum efficiency of InGaN yellow-green light-emitting diodes by growth interruption  

SciTech Connect (OSTI)

We studied the effect of multiple interruptions during the quantum well growth on emission-efficiency enhancement of InGaN-based yellow-green light emitting diodes on c-plane sapphire substrate. The output power and dominant wavelength at 20?mA are 0.24 mW and 556.3?nm. High resolution x-ray diffraction, photoluminescence, and electroluminescence measurements demonstrate that efficiency enhancement could be partially attributed to crystal quality improvement of the active region resulted from reduced In clusters and relevant defects on the surface of InGaN layer by introducing interruptions. The less tilted energy band in the quantum well is also caused by the decrease of In-content gradient along c-axis resulted from In segregation during the interruptions, which increases spatial overlap of electron-hole wavefunction and thus the internal quantum efficiency. The latter also leads to smaller blueshift of dominant wavelength with current increasing.

Du, Chunhua; Ma, Ziguang; Zhou, Junming; Lu, Taiping; Jiang, Yang; Zuo, Peng; Jia, Haiqiang; Chen, Hong, E-mail: hchen@iphy.ac.cn [Key Laboratory for Renewable Energy, Chinese Academy of Sciences, Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condense Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2014-08-18T23:59:59.000Z

55

InGaAsBi alloys on InP for efficient near- and mid-infrared light emitting devices  

SciTech Connect (OSTI)

We present the band parameters such as band gap, spin-orbit splitting energy, band offsets and strain of InGaAsBi on InP based on recent experimental data. It is shown that InGaAsBi is promising for near- and mid-infrared photonic devices operating from 0.3–0.8?eV (1.5–4??m) on conventional InP substrates. We also show how bismuth may be used to form alloys whereby the spin-orbit splitting energy (?{sub SO}) is large and controllable and can, for example, be made larger than the band gap (E{sub g}) thereby providing a means of suppressing non-radiative hot-hole producing Auger recombination and inter-valence band absorption both involving the spin-orbit band. This is expected to improve the high-temperature performance and thermal stability of light emitting devices.

Jin, Shirong; John Sweeney, Stephen [Advanced Technology Institute and Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

2013-12-07T23:59:59.000Z

56

Modeling of temperature and excitation dependences of efficiency in an InGaN light-emitting diode  

E-Print Network [OSTI]

The changes in excitation dependence of efficiency with temperature is modeled for a wurtzite InGaN light-emitting diode. The model incorporates bandstructure changes with carrier density arising from screening of quantum-confined Stark effect. Bandstructure is computed by solving Poisson and k.p equations in the envelop approximation. The information is used in a dynamical model for populations in momentum-resolved electron and hole states. Application of the approach shows the interplay of quantum-well and barrier emissions giving rise to shape changes in efficiency versus current density with changing temperature, as observed in some experiments.

Chow, Weng W

2013-01-01T23:59:59.000Z

57

Influences of excitation-dependent bandstructure changes on InGaN light-emitting diode efficiency  

E-Print Network [OSTI]

Bandstructure properties in wurtzite quantum wells can change appreciably with changing carrier density because of screening of quantum-confined Stark effect. An approach for incorporating these changes in an InGaN light-emitting-diode model is described. Bandstructure is computed for different carrier densities by solving Poisson and k\\cdotp equations in the envelop approximation. The information is used as input in a dynamical model for populations in momentum-resolved electron and hole states. Application of the approach is illustrated by modeling device internal quantum efficiency as a function of excitation.

Chow, Weng W

2011-01-01T23:59:59.000Z

58

An intentionally positioned (In,Ga)As quantum dot in a micron sized light emitting diode  

SciTech Connect (OSTI)

We have integrated individual (In,Ga)As quantum dots (QDs) using site-controlled molecular beam epitaxial growth into the intrinsic region of a p-i-n junction diode. This is achieved using an in situ combination of focused ion beam prepatterning, annealing, and overgrowth, resulting in arrays of individually electrically addressable (In,Ga)As QDs with full control on the lateral position. Using microelectroluminescence spectroscopy we demonstrate that these QDs have the same optical quality as optically pumped Stranski-Krastanov QDs with random nucleation located in proximity to a doped interface. The results suggest that this technique is scalable and highly interesting for different applications in quantum devices.

Mehta, M.; Michaelis de Vasconcellos, S.; Zrenner, A.; Meier, C. [Department of Physics and Center for Optoelectronics and Photonics Paderborn (CeOPP), University of Paderborn, Warburger Street 100, 33098 Paderborn (Germany); Reuter, D.; Wieck, A. D. [Applied Solid State Physics, Ruhr-University of Bochum, Universitaetsstr. 150, 44780 Bochum (Germany)

2010-10-04T23:59:59.000Z

59

Enhancement of Radiative Efficiency with Staggered InGaN Quantum Well Light Emitting Diodes  

SciTech Connect (OSTI)

The technology on the large overlap InGaN QWs developed in this program is currently implemented in commercial technology in enhancing the internal quantum efficiency in major LED industry in US and Asia. The scientific finding from this work supported by the DOE enabled the implementation of this step-like staggered quantum well in the commercial LEDs.

Tansu, Nelson; Dierolf, Volkmar; Huang, Gensheng; Penn, Samson; Zhao, Hongping; Liu, Guangyu; Li, Xiaohang; Poplawsky, Jonathan

2011-07-14T23:59:59.000Z

60

Electrical, optical, and material characterizations of blue InGaN light emitting diodes submitted to reverse-bias stress in water vapor condition  

SciTech Connect (OSTI)

In this paper, we investigate degradation of InGaN/GaN light emitting diodes (LEDs) under reverse-bias operations in water vapor and dry air. To examine failure origins, electrical characterizations including current-voltage, breakdown current profiles, optical measurement, and multiple material analyses were performed. Our findings indicate that the diffusion of indium atoms in water vapor can expedite degradation. Investigation of reverse-bias stress can help provide insight into the effects of water vapor on LEDs.

Chen, Hsiang, E-mail: hchen@ncnu.edu.tw; Chu, Yu-Cheng; Chen, Yun-Ti; Chen, Chian-You [Department of Applied Materials and Optoelectronic Engineering, National Chi Nan University, No. 1, University Road, Puli, Nantou County 54561, Taiwan (China); Shei, Shih-Chang [Department of Electrical Engineering, National University of Tainan, No.33, Sec. 2, Shulin St., West Central Dist., Tainan City 70005, Taiwan (China)

2014-09-07T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Effects of Mg-doped AlN/AlGaN superlattices on properties of p-GaN contact layer and performance of deep ultraviolet light emitting diodes  

SciTech Connect (OSTI)

Mg-doped AlN/AlGaN superlattice (Mg-SL) and Mg-doped AlGaN epilayers have been investigated in the 284 nm deep ultraviolet (DUV) light emitting diodes (LEDs) as electron blocking layers. It was found that the use of Mg-SL improved the material quality of the p-GaN contact layer, as evidenced in the decreased density of surface pits and improved surface morphology and crystalline quality. The performance of the DUV LEDs fabricated using Mg-SL was significantly improved, as manifested by enhanced light intensity and output power, and reduced turn-on voltage. The improved performance is attributed to the enhanced blocking of electron overflow, and enhanced hole injection.

Al tahtamouni, T. M., E-mail: talal@yu.edu.jo [Department of Physics, Yarmouk University, Irbid 21163 (Jordan); Lin, J. Y.; Jiang, H. X. [Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)] [Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)

2014-04-15T23:59:59.000Z

62

Le disque comme document 1 Karim Hammou  

E-Print Network [OSTI]

en France tome 2, L'Harmattan, 2012, pp.177-193. Le disque comme document : une analyse quantitative'action musicale, Paris, L'Harmattan, 2007, p.45 et suiv. 3 Beuscart, J.-S., « L'industrie du disque : bil

Paris-Sud XI, Université de

63

COMMUNICATION www.comm.pdx.edu  

E-Print Network [OSTI]

COMMUNICATION www.comm.pdx.edu Undergraduate Degrees Offered: Bachelor of Arts in Communication Bachelor of Science in Communication Minor in Communication e Department of Communication offers a variety degrees in two areas of academic concentration include mediated communication and interactive discourse

64

Visible-light absorption and large band-gap bowing of GaN1-xSbx from first principles  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

Applicability of the Ga(Sbx)N1-x alloys for practical realization of photoelectrochemical water splitting is investigated using first-principles density functional theory incorporating the local density approximation and generalized gradient approximation plus the Hubbard U parameter formalism. Our calculations reveal that a relatively small concentration of Sb impurities is sufficient to achieve a significant narrowing of the band gap, enabling absorption of visible light. Theoretical results predict that Ga(Sbx)N1-x alloys with 2-eV band gaps straddle the potential window at moderate to low pH values, thus indicating that dilute Ga(Sbx)N1-x alloys could be potential candidates for splitting water under visible light irradiation.

Sheetz, R. Michael; Richter, Ernst; Andriotis, Antonis N.; Lisenkov, Sergey; Pendyala, Chandrashekhar; Sunkara, Mahendra K.; Menon, Madhu

2011-08-01T23:59:59.000Z

65

Princeton Public Utils Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating Solar Powerstories onFocusOskiPhilipspresents new Climate Action PlanUtils Comm Jump

66

Mohawk Municipal Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating Solar Powerstories onFocus Area EnergyMohawk Municipal Comm Jump to: navigation,

67

Crisp County Power Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating Solar Power Basics (The following text isRica NRELPower Comm Jump to: navigation,

68

Greenwood Utilities Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating Solar Power BasicsGermany: Energy ResourcesNews Home >Greenwood Utilities Comm

69

Confocal microphotoluminescence of InGaN-based light-emitting diodes Koichi Okamoto,a  

E-Print Network [OSTI]

for conventional incandescent and fluorescent light bulbs.5 However, luminous efficacies of commercial white LEDs spectrum region, the external quantum efficiency ext of the LED has achieved 20% at room temperature 25 lm/W have been still lower than that of fluorescent tubes 75 lm/W . Thus, the most important re

Okamoto, Koichi

70

A Light-Matter Interface based on a Single InAs/GaAs Quantum Dot in a Nanometallic Cavity  

E-Print Network [OSTI]

Progress in solid-state optical cavities is tracked on a timeline of miniaturization. Here, we demonstrate a coupled emitter-cavity system consisting of an InAs/GaAs Quantum Dot embedded in a hybrid metal/semiconductor nanocavity. Key features of our nanometallic light-matter interface include: (i) order of magnitude reduction in mode volume compared to that of leading photonic crystal cQED systems, resulting in maximum atom-field coupling rate g/(2{\\pi})~180GHz; (ii) surface-emitting nanocylinder geometry and therefore good collection efficiency compared to the bulk (~5X enhancement); (iii) strong and broadband spontaneous emission rate enhancement (Purcell factor ~8); and finally (iv) the ability to efficiently optically address a multi-level quantum emitter based on a charged quantum dot inside the nanocavity. This light-matter interface could play an important role in studies of the cavity quantum electrodynamics as well as in its application to optical interconnects and quantum networks.

Thomas M. Babinec; Yousif A. Kelaita; Kevin A. Fischer; Konstantinos G. Lagoudakis; Tomas Sarmiento; Armand Rundquist; Arka Majumdar; Jelena Vuckovic

2014-06-27T23:59:59.000Z

71

Direct Water Splitting under Visible Light with Nanostructured Hematite and WO3 Photoanodes and a GaInP2 Photocathode  

SciTech Connect (OSTI)

A p-GaInP{sub 2} photocathode was paired with nanostructured hematite and tungsten trioxide photoanodes to investigate the utility of these systems for direct water splitting under visible light illumination. For the hematite system, under illumination at open-circuit conditions, the potential of hematite shifts cathodically and that of the GaInP{sub 2} shifts anodically. Under short-circuit condition and visible light illumination, the combination of the two photoelectrodes can split water, though with a very low rate of a few {micro}A/cm{sup 2} even at an intensity of 1 W/cm{sup 2}. It was determined that the very low photocurrent from the hematite nanorod photoelectrode limits the short-circuit current of the two-photoelectrode combination. Similar potential shifts were observed with the nanostructured WO{sub 3}/GaInP{sub 2} combination. However, at light intensities below 0.2 W/cm{sup 2}, the short-circuited combination would not split water due to an insufficient potential difference. Above 0.2 W/cm{sup 2}, the combination can split water under visible light, with {approx}20 {micro}A/cm{sup 2} obtained at 1 W/cm{sup 2}. A linear photocurrent-light intensity relationship was observed and was attributed to efficient charge transfer and a low recombination of the charge carriers. The bandgap and the associated absorption limit of WO{sub 3} remain a challenge for a higher efficiency system.

Wang, H.; Deutsch, T.; Turner, J. A.

2008-01-01T23:59:59.000Z

72

GaN-based light-emitting diode with textured indium tin oxide transparent layer coated with Al{sub 2}O{sub 3} powder  

SciTech Connect (OSTI)

Surface-textured InGaN/GaN light-emitting diodes (LEDs) coated with transparent Al{sub 2}O{sub 3} powder were fabricated by natural lithography combined with inductively coupled plasma etching. For surface texturing, 300 nm size Al{sub 2}O{sub 3} powder is used as an etching mask by simply coating the surface using a spin-coating process. Also, the powders are left on the surface after surface texturing to further increase extraction efficiency. At 20 mA, the light output power of the textured indium tin oxide (ITO) InGaN/GaN LEDs coated with the Al{sub 2}O{sub 3} powder is enhanced by {approx}112% compared with the conventional nontextured ITO LED. The enhanced light output power is attributed to the improved extraction efficiency resulting from an overall decrease in the total internal reflection due to the textured surface and the Al{sub 2}O{sub 3} powder coating.

Kim, T. K.; Kim, S. H.; Yang, S. S.; Son, J. K.; Lee, K. H.; Hong, Y. G.; Shim, K. H.; Yang, J. W.; Lim, K. Y.; Yang, G. M. [Department of Semiconductor and Chemical Engineering and Semiconductor Physics Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Bae, S. J. [Optowell Co., Ltd., 308, Semiconductor Physics Research Center, 664-14, Dukjin-Dong, Dukjin-Gu, Jeonju 561-756 (Korea, Republic of)

2009-04-20T23:59:59.000Z

73

Wyandotte Municipal Serv Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:SeadovCooperative JumpWilliamsonWoodson County,Worden,Wrightsville,WurthServ Comm Jump to:

74

Easton Utilities Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating Solar Power Basics (The followingDirectLow CarbonOpen1 June, 2013Easton Utilities Comm

75

Henderson City Utility Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating Solar Power BasicsGermany: EnergyPower Finance Jump737002°,HavanaElorblocksComm Jump

76

Bias dependence and correlation of the cathodoluminescence and electron beam induced current from an InGaN/GaN light emitting diode  

SciTech Connect (OSTI)

Micron-scale mapping has been employed to study a contacted InGaN/GaN LED using combined electroluminescence (EL), cathodoluminescence (CL), and electron beam induced current (EBIC). Correlations between parameters, such as the EBIC and CL intensity, were studied as a function of applied bias. The CL and EBIC maps reveal small areas, 2–10??m in size, which have increased nonradiative recombination rate and/or a lower conductivity. The CL emission from these spots is blue shifted, by 30–40?meV. Increasing the reverse bias causes the size of the spots to decrease, due to competition between in-plane diffusion and drift in the growth direction. EL mapping shows large bright areas (?100??m) which also have increased EBIC, indicating domains of increased conductivity in the p and/or n-GaN.

Wallace, M. J.; Edwards, P. R.; Martin, R. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Kappers, M. J.; Oehler, F.; Oliver, R. A.; Humphreys, C. J. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Hopkins, M. A.; Sivaraya, S.; Allsopp, D. W. E. [Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY (United Kingdom)

2014-07-21T23:59:59.000Z

77

Doubly resonant second harmonic generation of 2.0 pm light in coupled InGaAs/AIAs quantum wells  

E-Print Network [OSTI]

energiesin n-type QWs to reach the technologically important 2 pm wavelength,6,7 where compact InGaAsP and Ga. The absorption spectrum of the sample is shown in Fig. 2. Absorption peaks at Et,=300 meV (4.1

Fejer, Martin M.

78

Sun Prairie Water & Light Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating SolarElectric Coop, Inc Place: MissouriPrograms |Illinois

79

North Branch Water & Light Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia: Energy ResourcesLoading map...(Utility Company) Jump to:City)Norristown,Braddock is a borough in AlleghenyBranch

80

Albany Water Gas & Light Comm | Open Energy Information  

Open Energy Info (EERE)

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Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Brodhead Water & Lighting Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 NoPublic Utilities Address: 160Benin: EnergyBoston Area SolarConnecticut:659243°Broadwind Energy Formerly

82

Moose Lake Water & Light Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating Solar Powerstories onFocus Area EnergyMohawk MunicipalMontvale, New Jersey:Water &

83

Waterloo Light & Water Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating SolarElectric Coop,Save EnergyGlouster,Winside,Warren County Rural EHeatersCBSWaterloo

84

Cedarburg Light & Water Comm | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 NoPublic Utilities Address: 160Benin:Energy Information on PV EconomicsOregon: Energy Resources Jump

85

Nanospherical-lens lithographical Ag nanodisk arrays embedded in p-GaN for localized surface plasmon-enhanced blue light emitting diodes  

SciTech Connect (OSTI)

Large-scale Ag nanodisks (NDs) arrays fabricated using nanospherical-lens lithography (NLL) are embedded in p-GaN layer of an InGaN/GaN light-emitting diode (LED) for generating localized surface plasmon (LSP) coupling with the radiating dipoles in the quantum-well (QWs). Based on the Ag NDs with the controlled surface coverage, LSP leads to the improved crystalline quality of regrowth p-GaN, increased photoluminescence (PL) intensity, reduced PL decay time, and enhanced output power of LED. Compared with the LED without Ag NDs, the optical output power at a current of 350 mA of the LSP-enhanced LEDs with Ag NDs having a distance of 20 and 35 nm to QWs is increased by 26.7% and 31.1%, respectively. The electrical characteristics and optical properties of LEDs with embedded Ag NPs are dependent on the distance of between Ag NPs and QWs region. The LED with Ag NDs array structure is also found to exhibit reduced emission divergence, compared to that without Ag NDs.

Wei, Tongbo, E-mail: tbwei@semi.ac.cn; Wu, Kui; Sun, Bo; Zhang, Yonghui; Chen, Yu; Huo, Ziqiang; Hu, Qiang; Wang, Junxi; Zeng, Yiping; Li, Jinmin [State Key Laboratory of Solid-State Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 (China); Lan, Ding [National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100080 (China)

2014-06-15T23:59:59.000Z

86

Enhanced optical power of GaN-based light-emitting diode with compound photonic crystals by multiple-exposure nanosphere-lens lithography  

SciTech Connect (OSTI)

The light-emitting diodes (LEDs) with single, twin, triple, and quadruple photonic crystals (PCs) on p-GaN are fabricated by multiple-exposure nanosphere-lens lithography (MENLL) process utilizing the focusing behavior of polystyrene spheres. Such a technique is easy and economical for use in fabricating compound nano-patterns. The optimized tilted angle is decided to be 26.6° through mathematic calculation to try to avoid the overlay of patterns. The results of scanning electron microscopy and simulations reveal that the pattern produced by MENLL is a combination of multiple ovals. Compared to planar-LED, the light output power of LEDs with single, twin, triple, and quadruple PCs is increased by 14.78%, 36.03%, 53.68%, and 44.85% under a drive current 350?mA, respectively. Furthermore, all PC-structures result in no degradation of the electrical properties. The stimulated results indicate that the highest light extraction efficiency of LED with the clover-shape triple PC is due to the largest scattering effect on propagation of light from GaN into air.

Zhang, Yonghui; Wei, Tongbo, E-mail: tbwei@semi.ac.cn; Xiong, Zhuo; Shang, Liang; Tian, Yingdong; Zhao, Yun; Zhou, Pengyu; Wang, Junxi; Li, Jinmin [Semiconductor Lighting Technology Research and Development Center, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

2014-07-07T23:59:59.000Z

87

Nanoscale-accuracy transfer printing of ultra-thin AlInGaN light-emitting diodes onto mechanically flexible substrates  

SciTech Connect (OSTI)

The transfer printing of 2 ?m-thick aluminum indium gallium nitride (AlInGaN) micron-size light-emitting diodes with 150?nm (±14?nm) minimum spacing is reported. The thin AlInGaN structures were assembled onto mechanically flexible polyethyleneterephthalate/polydimethylsiloxane substrates in a representative 16 × 16 array format using a modified dip-pen nano-patterning system. Devices in the array were positioned using a pre-calculated set of coordinates to demonstrate an automated transfer printing process. Individual printed array elements showed blue emission centered at 486?nm with a forward-directed optical output power up to 80??W (355 mW/cm{sup 2}) when operated at a current density of 20?A/cm{sup 2}.

Trindade, A. J., E-mail: antonio.trindade@strath.ac.uk; Guilhabert, B.; Massoubre, D.; Laurand, N.; Gu, E.; Watson, I. M.; Dawson, M. D. [Institute of Photonics, SUPA, University of Strathclyde, 106 Rottenrow, Glasgow G4 0NW (United Kingdom)] [Institute of Photonics, SUPA, University of Strathclyde, 106 Rottenrow, Glasgow G4 0NW (United Kingdom); Zhu, D.; Humphreys, C. J. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)] [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

2013-12-16T23:59:59.000Z

88

Migration enhanced lateral epitaxial overgrowth of AlN and AlGaN for high reliability deep ultraviolet light emitting diodes  

SciTech Connect (OSTI)

We report on the growth of low-defect thick films of AlN and AlGaN on trenched AlGaN/sapphire templates using migration enhanced lateral epitaxial overgrowth. Incoherent coalescence-related defects were alleviated by controlling the tilt angle of growth fronts and by allowing Al adatoms sufficient residence time to incorporate at the most energetically favorable lattice sites. Deep ultraviolet light emitting diode structures (310 nm) deposited over fully coalesced thick AlN films exhibited cw output power of 1.6 mW at 50 mA current with extrapolated lifetime in excess of 5000 hours. The results demonstrate substantial improvement in the device lifetime, primarily due to the reduced density of growth defects.

Jain, R.; Sun, W.; Yang, J.; Shatalov, M.; Hu, X.; Sattu, A.; Lunev, A.; Deng, J.; Shturm, I.; Bilenko, Y.; Gaska, R. [Sensor Electronic Technology, Inc., 1195 Atlas Road, Columbia, South Carolina 29209 (United States); Shur, M. S. [Electrical Computer and Systems Engineering, Rensselaer Polytechnic Institute, Troy New York 12180 (United States)

2008-08-04T23:59:59.000Z

89

Analysis of the causes of the decrease in the electroluminescence efficiency of AlGaInN light-emitting-diode heterostructures at high pumping density  

SciTech Connect (OSTI)

The study is devoted to theoretical explanation of a decrease in the electroluminescence efficiency as the pump current increases, which is characteristic of light-emitting-diode (LED) heterostructures based on AlInGaN. Numerical simulation shows that the increase in the external quantum efficiency at low current densities J {approx} 1 A/cm{sup 2} is caused by the competition between radiative and nonradiative recombination. The decrease in the quantum efficiency at current densities J > 1 A/cm{sup 2} is caused by a decrease in the efficiency of hole injection into the active region. It is shown that the depth of the acceptor energy level in the AlGaN emitter, as well as low electron and hole mobilities in the p-type region, plays an important role in this effect. A modified LED heterostructure is suggested in which the efficiency decrease with the pump current should not occur.

Rozhansky, I. V., E-mail: igor@quantum.ioffe.ru; Zakheim, D. A. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2006-07-15T23:59:59.000Z

90

Depth-resolved confocal micro-Raman spectroscopy for characterizing GaN-based light emitting diode structures  

SciTech Connect (OSTI)

In this work, we demonstrate that depth-resolved confocal micro-Raman spectroscopy can be used to characterize the active layer of GaN-based LEDs. By taking the depth compression effect due to refraction index mismatch into account, the axial profiles of Raman peak intensities from the GaN capping layer toward the sapphire substrate can correctly match the LED structural dimension and allow the identification of unique Raman feature originated from the 0.3 ?m thick active layer of the studied LED. The strain variation in different sample depths can also be quantified by measuring the Raman shift of GaN A{sub 1}(LO) and E{sub 2}(high) phonon peaks. The capability of identifying the phonon structure of buried LED active layer and depth-resolving the strain distribution of LED structure makes this technique a potential optical and remote tool for in operando investigation of the electronic and structural properties of nitride-based LEDs.

Chen, Wei-Liang; Lee, Yu-Yang; Chang, Yu-Ming, E-mail: ymchang@ntu.edu.tw [Center for Condensed Matter Sciences, National Taiwan University, 10617 Taipei, Taiwan (China)] [Center for Condensed Matter Sciences, National Taiwan University, 10617 Taipei, Taiwan (China); Chang, Chiao-Yun; Huang, Huei-Min; Lu, Tien-Chang [Department of Photonics, National Chiao Tung University, 30010 Hsinchu, Taiwan (China)] [Department of Photonics, National Chiao Tung University, 30010 Hsinchu, Taiwan (China)

2013-11-15T23:59:59.000Z

91

Ga nanoparticle-enhanced photoluminescence of GaAs  

SciTech Connect (OSTI)

We have examined the influence of surface Ga nanoparticles (NPs) on the enhancement of GaAs photoluminescence (PL) efficiency. We have utilized off-normal focused-ion-beam irradiation of GaAs surfaces to fabricate close-packed Ga NP arrays. The enhancement in PL efficiency is inversely proportional to the Ga NP diameter. The maximum PL enhancement occurs for the Ga NP diameter predicted to maximize the incident electromagnetic (EM) field enhancement. The PL enhancement is driven by the surface plasmon resonance (SPR)-induced enhancement of the incident EM field which overwhelms the SPR-induced suppression of the light emission.

Kang, M.; Al-Heji, A. A.; Jeon, S.; Wu, J. H. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Lee, J.-E.; Saucer, T. W.; Zhao, L.; Sih, V. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)] [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States); Katzenstein, A. L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, Eckerd College, St. Petersburg, Florida 33711-4744 (United States); Sofferman, D. L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, Adelphi University, Garden City, New York 11530-0701 (United States); Goldman, R. S. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

2013-09-02T23:59:59.000Z

92

Spontaneous emission in GaN/InGaN photonic crystal nanopillars  

E-Print Network [OSTI]

. Sigalas, "InGaN/GaN quantum-well heterostructure light-emitting diodes employing photonic crystal, "III-nitride blue and ultraviolet photonic crystal light emitting diodes," Appl. Phys. Lett. 84, 466, and H. Benisty, "Photonic-crystal GaN light-emitting diodes with tailored guided modes distribution

Boyer, Edmond

93

Colorado River Comm of Nevada | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of Inspector GeneralDepartmentAUDITOhioOglesby,Sullivan,Information FeedColombia: Energy ResourcesComm of

94

Materials for light-induced water splitting: In situ controlled surface preparation of GaPN epilayers grown lattice-matched on Si(100)  

SciTech Connect (OSTI)

Energy storage is a key challenge in solar-driven renewable energy conversion. We promote a photochemical diode based on dilute nitride GaPN grown lattice-matched on Si(100), which could reach both high photovoltaic efficiencies and evolve hydrogen directly without external bias. Homoepitaxial GaP(100) surface preparation was shown to have a significant impact on the semiconductor-water interface formation. Here, we grow a thin, pseudomorphic GaP nucleation buffer on almost single-domain Si(100) prior to GaPN growth and compare the GaP{sub 0.98}N{sub 0.02}/Si(100) surface preparation to established P- and Ga-rich surfaces of GaP/Si(100). We apply reflection anisotropy spectroscopy to study the surface preparation of GaP{sub 0.98}N{sub 0.02} in situ in vapor phase epitaxy ambient and benchmark the signals to low energy electron diffraction, photoelectron spectroscopy, and x-ray diffraction. While the preparation of the Ga-rich surface is hardly influenced by the presence of the nitrogen precursor 1,1-dimethylhydrazine (UDMH), we find that stabilization with UDMH after growth hinders well-defined formation of the V-rich GaP{sub 0.98}N{sub 0.02}/Si(100) surface. Additional features in the reflection anisotropy spectra are suggested to be related to nitrogen incorporation in the GaP bulk.

Supplie, Oliver, E-mail: oliver.supplie@tu-ilmenau.de [Technische Universität Ilmenau, Institut für Physik, Gustav-Kirchhoff-Str. 5, 98684 Ilmenau (Germany); Helmholtz-Zentrum Berlin, Institute for Solar Fuels, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Humboldt-Universität zu Berlin, Institut für Physik, Newtonstr. 15, 12489 Berlin (Germany); May, Matthias M.; Stange, Helena [Helmholtz-Zentrum Berlin, Institute for Solar Fuels, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Humboldt-Universität zu Berlin, Institut für Physik, Newtonstr. 15, 12489 Berlin (Germany); Höhn, Christian [Helmholtz-Zentrum Berlin, Institute for Solar Fuels, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Lewerenz, Hans-Joachim [Helmholtz-Zentrum Berlin, Institute for Solar Fuels, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); California Institute of Technology, Joint Center for Artificial Photosynthesis, 1200 East California Boulevard, Pasadena, California 91125 (United States); Hannappel, Thomas [Technische Universität Ilmenau, Institut für Physik, Gustav-Kirchhoff-Str. 5, 98684 Ilmenau (Germany); Helmholtz-Zentrum Berlin, Institute for Solar Fuels, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)

2014-03-21T23:59:59.000Z

95

E-Print Network 3.0 - algainp light-emitting diodes Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

by sequentially adding components of different types. Six hundred AlGaInP GaAs light- emitting diode segments... of 600 AlGaInP GaAs light-emitting diodes (LEDs) onto device...

96

GaInN light-emitting diodes using separate epitaxial growth for the p-type region to attain polarization-inverted electron-blocking layer, reduced electron leakage, and improved hole injection  

SciTech Connect (OSTI)

A GaInN light-emitting diode (LED) structure is analyzed that employs a separate epitaxial growth for the p-type region, i.e., the AlGaN electron-blocking layer (EBL) and p-type GaN cladding layer, followed by wafer or chip bonding. Such LED structure has a polarization-inverted EBL and allows for uncompromised epitaxial-growth optimization of the p-type region, i.e., without the need to consider degradation of the quantum-well active region during p-type region growth. Simulations show that such an LED structure reduces electron leakage, reduces the efficiency droop, improves hole injection, and has the potential to extend high efficiencies into the green spectral region.

Meyaard, David S., E-mail: meyaad@rpi.edu; Lin, Guan-Bo; Ma, Ming; Fred Schubert, E. [Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)] [Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Cho, Jaehee [Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States) [Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Semiconductor Physics Research Center, School of Semiconductor and Chemical Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Han, Sang-Heon; Kim, Min-Ho; Shim, HyunWook; Sun Kim, Young [LED Business, Samsung Electronics, Yongin 446-920 (Korea, Republic of)] [LED Business, Samsung Electronics, Yongin 446-920 (Korea, Republic of)

2013-11-11T23:59:59.000Z

97

Comparison of the properties of AlGaInN light-emitting diode chips of vertical and flip-chip design using silicon as the a submount  

SciTech Connect (OSTI)

Vertical and flip-chip light-emitting diode (LED) chips are compared from the viewpoint of the behavior of current spreading in the active region and the distribution of local temperatures and thermal resistances of chips. AlGaInN LED chips of vertical design are fabricated using Si as a submount and LED flipchips were fabricated with the removal of a sapphire substrate. The latter are also mounted on a Si submount. The active regions of both chips are identical and are about 1 mm{sup 2} in size. It is shown that both the emittance of the crystal surface in the visible range and the distribution of local temperatures estimated from radiation in the infrared region are more uniform in crystals of vertical design. Heat removal from flip-chips is insufficient in regions of the n contact, which do not possess good thermal contact with the submount. As a result, the total thermal resistances between the p-n junction and the submount both for the vertical chips and for flip-chips are approximately 1 K/W. The total area of the flip-chips exceeds that of the vertical design chips by a factor of 1.4.

Markov, L. K., E-mail: l.markov@mail.ioffe.ru; Smirnova, I. P.; Pavlyuchenko, A. S. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Kukushkin, M. V.; Vasil'eva, E. D. [ZAO Innovation 'Tetis' (Russian Federation); Chernyakov, A. E. [Russian Academy of Sciences, Science-and-Technology Microelectronics Center (Russian Federation); Usikov, A. S. [De Core Nanosemiconductors Ltd. (India)

2013-03-15T23:59:59.000Z

98

Luminescence characterization of (Ca{sub 1-x}Zn{sub x})Ga{sub 2}S{sub 4}:Eu{sup 2+} phosphors for a white light-emitting diode  

SciTech Connect (OSTI)

We investigated the luminescence properties of (Ca{sub 1-x}Zn{sub x})Ga{sub 2}S{sub 4}:Eu{sup 2+} phosphor as a function of Zn{sup 2+} and Eu{sup 2+} concentrations. The luminescence intensity was markedly enhanced by increasing the mole fraction of Zn{sup 2+} at Ca{sup 2+} sites. Lacking any Zn{sup 2+} ions, CaGa{sub 2}S{sub 4}:0.01Eu{sup 2+} converted only 18.1% of the absorbed blue light into luminescence. As the Zn{sup 2+} concentration increased, the quantum yield increased and reached a maximum of 24.4% at x = 0.1. Furthermore, to fabricate the device, the optimized green-yellow (Ca{sub 0.9}Zn{sub 0.1})Ga{sub 2}S{sub 4}:Eu{sup 2+} phosphor was coated with MgO. White light was generated by combining the MgO-coated phosphor and the blue emission from a GaN chip.

Kim, Yong-Kyu; Cho, Dong-Hee; Jeong, Yong-Kwang; Nah, Min-Kook [Department of Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of)] [Department of Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Kim, Kwang-Bok [Kumho Electric Inc., 64-1 Bongmyung-Ri, Namsa-Myun, Youngin, Gyeonggi-Do 449-883 (Korea, Republic of)] [Kumho Electric Inc., 64-1 Bongmyung-Ri, Namsa-Myun, Youngin, Gyeonggi-Do 449-883 (Korea, Republic of); Kang, Jun-Gill, E-mail: jgkang@cnu.ac.kr [Department of Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of)] [Department of Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

2010-08-15T23:59:59.000Z

99

CrystEngComm Cite this: CrystEngComm, 2014, 16,  

E-Print Network [OSTI]

energy storage,11 solar water splitting,12 photo- catalysis,13 and waste-water treatment.14 A great deal structure. Moreover, the mesocrystalline hematite nanoplates exhibited good visible-light photocatalytic in many areas such as cataly- sis, sensing, optoelectronics, biomedical materials, and energy storage

Qi, Limin

100

ORISE Resources: HealthCommWorks Communication Tool  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas Conchas recoveryLaboratory | NationalJohnSecurityControlsOMB Policies ORHealthCommWorks

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101

Fabrication of ZnO photonic crystals by nanosphere lithography using inductively coupled-plasma reactive ion etching with CH{sub 4}/H{sub 2}/Ar plasma on the ZnO/GaN heterojunction light emitting diodes  

SciTech Connect (OSTI)

This article reports fabrication of n-ZnO photonic crystal/p-GaN light emitting diode (LED) by nanosphere lithography to further booster the light efficiency. In this article, the fabrication of ZnO photonic crystals is carried out by nanosphere lithography using inductively coupled plasma reactive ion etching with CH{sub 4}/H{sub 2}/Ar plasma on the n-ZnO/p-GaN heterojunction LEDs. The CH{sub 4}/H{sub 2}/Ar mixed gas gives high etching rate of n-ZnO film, which yields a better surface morphology and results less plasma-induced damages of the n-ZnO film. Optimal ZnO lattice parameters of 200 nm and air fill factor from 0.35 to 0.65 were obtained from fitting the spectrum of n-ZnO/p-GaN LED using a MATLAB code. In this article, we will show our recent result that a ZnO photonic crystal cylinder has been fabricated using polystyrene nanosphere mask with lattice parameter of 200 nm and radius of hole around 70 nm. Surface morphology of ZnO photonic crystal was examined by scanning electron microscope.

Chen, Shr-Jia; Chang, Chun-Ming; Kao, Jiann-Shiun; Chen, Fu-Rong; Tsai, Chuen-Horng [Engineering and System Science, National Tsing Hua University, Hsinchu, 30013 Taiwan (China); Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu, 300 Taiwan (China); Engineering and System Science, National Tsing Hua University, Hsinchu, 30013 Taiwan (China)

2010-07-15T23:59:59.000Z

102

Roadmap: Communication Studies Public Communication Bachelor of Arts [CI-BA-COMM-PCMM  

E-Print Network [OSTI]

Roadmap: Communication Studies ­ Public Communication ­ Bachelor of Arts [CI-BA-COMM-PCMM] College of Communication and Information School of Communication Studies Catalog Year: 2012­2013 Page 1 of 3 | Last Updated Major GPA Important Notes Semester One: [16 Credit Hours] COMM 15000 Introduction to Human Communication

Sheridan, Scott

103

Roadmap: Communication Studies -Applied Communication -Bachelor of Arts [CI-BA-COMM-APCO  

E-Print Network [OSTI]

Roadmap: Communication Studies - Applied Communication - Bachelor of Arts [CI-BA-COMM-APCO] College of Communication and Information School of Communication Studies Catalog Year: 2012­2013 Page 1 of 3 | Last Updated Major GPA Important Notes Semester One: [16 Credit Hours] COMM 15000 Introduction to Human Communication

Sheridan, Scott

104

Photonic crystal light emitting diode.  

E-Print Network [OSTI]

?? This master's thesis describe electromagnetic simulations of a gallium antimonide (GaSb) light emitting diode, LED. A problem for such devices is that most of… (more)

Leirset, Erlend

2010-01-01T23:59:59.000Z

105

CONOMIE ET STATISTIQUE N 457-458, 201298 L'automobile est parfois perue comme  

E-Print Network [OSTI]

#12;�CONOMIE ET STATISTIQUE N° 457-458, 201298 L'automobile est parfois perçue comme emblématique d'équipement et aux consommations matérielles (Gartman, 1991). Il est ainsi parfois avancé que l'automobile ne- nismes socio-économiques. L'automobile est de ce fait souvent prise comme exemple d'un bien dont les

Paris-Sud XI, Université de

106

TESLA-FEL 2007-03 Application of low cost GaAs LED as neutron  

E-Print Network [OSTI]

neutrons in unbiased Gallium Arsenide (GaAs) Light Emitting Diodes (LED) resulted in a reduction Keywords: COTS components, Displacement damage, Electron Linear Accelerator, GaAs Light emitting diode (LED) Gallium Arsenide (GaAs) light emitting diode (LED) for the assessment of integrated neutron fluence

107

Optical remote monitoring of CH/sub 4/ gas using low-loss optical fiber link and InGaAsP light-emitting diode in 1. 33-. mu. m region  

SciTech Connect (OSTI)

Purely optical remote monitoring of low-level CH/sub 4/ gas is realized for the first time by the method employing a 2-km long-distance, low-loss silica optical fiber link and a compact absorption cell in conjunction with a high radiant InGaAsP light-emitting diode (LED) at 1.33 ..mu..m. Based on the present experiment, the detection limit of CH/sub 4/ in air was confirmed to be approximately 2000 ppm, i.e., 4% of the lower explosion limit of CH/sub 4/. This result supports the conclusion that the fully optical remote sensing system incorporating ultralow loss optical fiber networks and near infrared LEDs or laser diodes can be extensively used for the detection and surveillance of various inflammable and/or explosive gases in industrial and mining complexes as well as in residential areas.

Chan, K.; Ito, H.; Inaba, H.

1983-10-01T23:59:59.000Z

108

de l'manation du thorium, on peut considrer le nombre 9,5 ions comme reprsentant assez bien,  

E-Print Network [OSTI]

75 de l'émanation du thorium, on peut considérer le nombre 9,5 ions comme représentant assez bien

Boyer, Edmond

109

Nanostructured light-absorbing crystalline CuIn{sub (1–x)}Ga{sub x}Se{sub 2} thin films grown through high flux, low energy ion irradiation  

SciTech Connect (OSTI)

A hybrid effusion/sputtering vacuum system was modified with an inductively coupled plasma (ICP) coil enabling ion assisted physical vapor deposition of CuIn{sub 1?x}Ga{sub x}Se{sub 2} thin films on GaAs single crystals and stainless steel foils. With <80 W rf power to the ICP coil at 620–740 °C, film morphologies were unchanged compared to those grown without the ICP. At low temperature (600–670 °C) and high rf power (80–400 W), a light absorbing nanostructured highly anisotropic platelet morphology was produced with surface planes dominated by (112){sub T} facets. At 80–400 W rf power and 640–740 °C, both interconnected void and small platelet morphologies were observed while at >270 W and above >715 °C nanostructured pillars with large inter-pillar voids were produced. The latter appeared black and exhibited a strong (112){sub T} texture with interpillar twist angles of ±8°. Application of a negative dc bias of 0–50 V to the film during growth was not found to alter the film morphology or stoichiometry. The results are interpreted as resulting from the plasma causing strong etching favoring formation of (112){sub T} planes and preferential nucleation of new grains, balanced against conventional thermal diffusion and normal growth mechanisms at higher temperatures. The absence of effects due to applied substrate bias suggests that physical sputtering or ion bombardment effects were minimal. The nanostructured platelet and pillar films were found to exhibit less than one percent reflectivity at angles up to 75° from the surface normal.

Hall, Allen J.; Hebert, Damon; Rockett, Angus A. [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, Illinois 61801 (United States)] [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, Illinois 61801 (United States); Shah, Amish B. [Center for Microanalysis of Materials, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, 104 South Goodwin Ave, Urbana, Illinois 61801 (United States)] [Center for Microanalysis of Materials, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, 104 South Goodwin Ave, Urbana, Illinois 61801 (United States); Bettge, Martin [Chemical Sciences and Engineering, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60438 (United States)] [Chemical Sciences and Engineering, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60438 (United States)

2013-10-21T23:59:59.000Z

110

LA CERTIFICATION FORESTIERE COMME NORME DE GESTION DURABLE DES FORETS TROPICALES : UNE LABORIEUSE APPLICATION EN AFRIQUE  

E-Print Network [OSTI]

LA CERTIFICATION FORESTIERE COMME NORME DE GESTION DURABLE DES FORETS TROPICALES : UNE LABORIEUSE sous l'effet de pressions du marché européen que par souci écologique de gestion durable des forêts nombreuses Organisations Non Gouvernementales Internationales (ONGI) basées dans les pays du Nord et militant

Boyer, Edmond

111

Cite this: CrystEngComm, 2013, 15, Calcite formation by hydrothermal carbonation of  

E-Print Network [OSTI]

Cite this: CrystEngComm, 2013, 15, 3392 Calcite formation by hydrothermal carbonation by hydrothermal carbonation of calcium hydroxide by a simulation strategy, in which both the chemical evolution calcite formation by hydrothermal carbonation of portlandite. Calcite is an important ubiquitous mineral

Montes-Hernandez, German

112

LA DYNAMIQUE DES SYSTEMES COMME OUTIL D'AIDE A LA GESTION DU SOL URBAIN  

E-Print Network [OSTI]

LA DYNAMIQUE DES SYSTEMES COMME OUTIL D'AIDE A LA GESTION DU SOL URBAIN Monique DANTAS Doctorante qui le composent sont interreliées. Tel est le cas du sol urbain dont la complexité des interactions rend délicate la mise en place de politiques adaptées. La construction d'un modèle de gestion du sol

Paris-Sud XI, Université de

113

Business Plan - RM MedComm's Opportunity for Business in Healthcare Design Services  

E-Print Network [OSTI]

Exhibit 1 ? Sales Forecast 11 Exhibit 2 ? NAICS Hierarchy for Engineering Services 19 Exhibit 3 ? Health Care Market Size 20 Exhibit 4 ? Customer Demand 27 Exhibit 5 ? Sales Forecast 31 Exhibit 6 ? Relationship Sales...?s demands, RM MedComm will increase the staff size as required. Forecast and Objectives The following forecast is based upon the prior listed assumptions in this section. At $165.7K per project and a $700M market, the number of health care projects...

Mason, Raymond

2005-12-16T23:59:59.000Z

114

COMM REF  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofof EnergyYou$0.C. 20545 OCTTO:March_BayoRECORD OF DECISION:L4

115

Nanoair-bridged lateral overgrowth of GaN on ordered nanoporous GaN template  

SciTech Connect (OSTI)

We report the growth of high-quality GaN epilayers on an ordered nanoporous GaN template by metalorganic chemical vapor deposition. The nanopores in GaN template were created by inductively coupled plasma etching using anodic aluminum oxide film as an etch mask. The average pore diameter and interpore distance is about 65 and 110 nm, respectively. Subsequent overgrowth of GaN first begins at the GaN crystallite surface between the pores, and then air-bridge-mediated lateral overgrowth leads to the formation of the continuous layer. Microphotoluminescence and micro-Raman measurements show improved optical properties and significant strain relaxation in the overgrown layer when compared to GaN layer of same thickness simultaneously grown on sapphire without any template. Similar to conventional epitaxial lateral overgrown GaN, such overgrown GaN on a nanopatterned surface would also serve as a template for the growth of ultraviolet-visible light-emitting III-nitride devices.

Wang, Y.D.; Zang, K.Y.; Chua, S.J.; Tripathy, S.; Chen, P.; Fonstad, C.G. [Singapore-MIT Alliance, E4-04-10, 4 Engineering Drive 3, Singapore 117576 (Singapore) and Centre for Optoelectronics, Department of Electrical and Computer Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602 (Singapore); Department of Electrical and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2005-12-19T23:59:59.000Z

116

Photoluminescence study of the 1.047 eV emission in GaN K. Pressela)  

E-Print Network [OSTI]

GaN/ AlGaN blue green light emitting diode, which has a much higher quantum efficiency than the SiC blue light emitting diode, became possible.2 Presently the wide bandgap semi- conductor GaN is intensively. Especially the 1.19 eV is very intense. Thus one can think of developing a light emitting diode in the near

Nabben, Reinhard

117

Journal of Light Emitting Diodes Vol 2 N0 1, April 2010 1 Abstract--In metal organic vapor phase epitaxy we developed  

E-Print Network [OSTI]

Journal of Light Emitting Diodes Vol 2 N0 1, April 2010 1 Abstract-- In metal organic vapor phase epitaxy we developed GaInN/GaN quantum well material suitable for 500 ­ 580 nm light emitting diodes at longer wavelengths. Index Terms-- a-plane GaN, GaInN, Green light emitting diode, m-plane GaN I

Wetzel, Christian M.

118

Structure and strain-relaxation effects of defects in InxGa1-xN epilayers  

E-Print Network [OSTI]

The direct band gap of InxGa1-xN can be engineered to emit light over the entire visible spectrum depending on the In content (x) of the film. InGaN-based alloys are thereby used to fabricate light-emitting diodes (LEDs), laser diodes (LDs) [1] [2... ] and solar cells [3] [4]. InGaN alloys are excellent candidates for the light-absorption layers in solar cell applications because of their high-energy radiation resistance [3] and because InGaN alloys across the 2 range of In compositions absorb light...

Rhode, S. L.; Fu, W. Y.; Moram, M. A.; Massabuau, F. C.-P.; Kappers, M. J.; McAleese, C.; Oehler, F.; Humphreys, C. J.; Dusane, R. O.; Sahonta, S.-L.

2014-09-10T23:59:59.000Z

119

Graphene/GaN diodes for ultraviolet and visible photodetectors  

SciTech Connect (OSTI)

The Schottky diodes based on graphene/GaN interface are fabricated and demonstrated for the dual-wavelength photodetection of ultraviolet (UV) and green lights. The physical mechanisms of the photoelectric response of the diodes with different light wavelengths are different. For UV illumination, the photo-generated carriers lower the Schottky barrier and increase the photocurrent. For green light illumination, as the photon energy is smaller than the bandgap of GaN, the hot electrons excited in graphene via internal photoemission are responsible for the photoelectric response. Using graphene as a transparent electrode, the diodes show a ?mS photoresponse, providing an alternative route toward multi-wavelength photodetectors.

Lin, Fang; Chen, Shao-Wen; Meng, Jie; Tse, Geoffrey; Fu, Xue-Wen; Xu, Fu-Jun [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Shen, Bo; Liao, Zhi-Min, E-mail: liaozm@pku.edu.cn, E-mail: yudp@pku.edu.cn; Yu, Da-Peng, E-mail: liaozm@pku.edu.cn, E-mail: yudp@pku.edu.cn [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)

2014-08-18T23:59:59.000Z

120

Band gap tuning in GaN through equibiaxial in-plane strains S. K. Yadav,2  

E-Print Network [OSTI]

in photovoltaics and light emission diodes LEDs . The InGaN system has been intensively studied during the past to the large atomic size mismatch between Ga and In.3 Thus, other methods to tune the band gap are needed for potential appli- cations of GaN and related materials systems. It is well-known that the structure

Alpay, S. Pamir

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

GaAs/AlGaAs quantum wells with indirect-gap AlGaAs barriers for solar cell applications  

SciTech Connect (OSTI)

We have fabricated GaAs/AlGaAs quantum well (QW) solar cells in which 3?nm-thick QWs and indirect-gap Al{sub 0.78}Ga{sub 0.22}As barriers are embedded, and we studied extraction processes of photogenerated carriers in this QW system. The photocurrent under 700?nm light illumination at voltages close to the open-circuit voltage shows only a small reduction, indicating that the carrier recombination inside QWs is largely suppressed. We attribute this result to an efficient extraction of electrons from the QWs through the X-valley of AlGaAs. The insertion of QWs is shown to be effective in extending the absorption wavelengths and in enhancing the photocurrent. The use of indirect-gap materials as barriers is found to enhance carrier extraction processes, and result in an improved performance of QW solar cells.

Noda, T., E-mail: NODA.Takeshi@nims.go.jp; Otto, L. M.; Elborg, M.; Jo, M.; Mano, T.; Kawazu, T.; Han, L. [National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Sakaki, H. [National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Toyota Technological Institute, Nagoya 468-8511 (Japan)

2014-03-24T23:59:59.000Z

122

Photocapacitance study of type-II GaSb/GaAs quantum ring solar cells  

SciTech Connect (OSTI)

In this study, the density of states associated with the localization of holes in GaSb/GaAs quantum rings are determined by the energy selective charging of the quantum ring distribution. The authors show, using conventional photocapacitance measurements, that the excess charge accumulated within the type-II nanostructures increases with increasing excitation energies for photon energies above 0.9?eV. Optical excitation between the localized hole states and the conduction band is therefore not limited to the ?(k?=?0) point, with pseudo-monochromatic light charging all states lying within the photon energy selected. The energy distribution of the quantum ring states could consequently be accurately related from the excitation dependence of the integrated photocapacitance. The resulting band of localized hole states is shown to be well described by a narrow distribution centered 407?meV above the GaAs valence band maximum.

Wagener, M. C.; Botha, J. R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Carrington, P. J.; Krier, A. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

2014-01-07T23:59:59.000Z

123

14 MHz rate photon counting with room temperature InGaAs/InP avalanche photodiodes  

E-Print Network [OSTI]

14 MHz rate photon counting with room temperature InGaAs/InP avalanche photodiodes PAUL L. VOSS based on InGaAs/InP avalanche photodiodes for use at 1.55 mm wavelength. Operation at room temperature at the above wavelengths for conventional high light-level measurements with PIN or ava- lanche photodiodes

Köprülü, Kahraman Güçlü

124

AlGaN/GaN-based power semiconductor switches  

E-Print Network [OSTI]

AlGaN/GaN-based high-electron-mobility transistors (HEMTs) have great potential for their use as high efficiency and high speed power semiconductor switches, thanks to their high breakdown electric field, mobility and ...

Lu, Bin, Ph. D. Massachusetts Institute of Technology

2013-01-01T23:59:59.000Z

125

Luminescence properties of light-emitting diodes based on GaAs with the up-conversion Y{sub 2}O{sub 2}S:Er,Yb luminophor  

SciTech Connect (OSTI)

Y{sub 2}O{sub 2}S luminophors doped with Er{sup 3+} and Yb{sup 3+} ions are produced by means of solid-phase synthesis and deposited onto standard AL123A infrared light-emitting diodes. When excited with 940 nm radiation from a light-emitting diode, the structures exhibit intense visible up-conversion luminescence. A maximal brightness of 2340 cd/m{sup 2} of green and red up-conversion luminescence at corresponding wavelengths around 550 and 600 nm is observed for the Y{sub 2}O{sub 2}S compound doped with 2 at % Er{sup 3+} ions and 6 at % Yb{sup 3+} ions. The ratio of the intensity of green (or red) up-conversion luminescence to the intensity of infrared Stokes luminescence increases with increasing applied voltage. The efficiency of visible emission of the light-emitting diode structures is {eta} = 1.2 lm/W at an applied voltage of 1.5 V.

Gruzintsev, A. N., E-mail: gran@ipmt-hpm.ac.ru [Russian Academy of Sciences, Institute of Problems of Microelectronics Technology (Russian Federation); Barthou, C.; Benalloul, P. [Institute des NanoSciences (France)

2008-03-15T23:59:59.000Z

126

Reducing the efficiency droop by lateral carrier confinement in InGaN/GaN quantum-well nanorods  

E-Print Network [OSTI]

Efficiency droop is a major obstacle facing high-power application of InGaN/GaN quantum-well (QW) light-emitting diodes. In this letter, we report the suppression of efficiency droop induced by density-activated defect recombination in nanorod structure of a-plane InGaN/GaN QWs. In the high carrier density regime, the retained emission efficiency in a dry-etched nanorod sample is observed to be over two times higher than that in its parent QW sample. We further argue that the improvement is a combined effect of the amendment contributed by lateral carrier confinement and the deterioration made by surface trapping.

Shi, Chentian; Yang, Fan; Park, Min Joo; Kwak, Joon Seop; Jung, Sukkoo; Choi, Yoon-Ho; Wang, Xiaoyong; Xiao, Min

2013-01-01T23:59:59.000Z

127

Design and Experimental Characterization of an Erbium Doped GaN Waveguide  

E-Print Network [OSTI]

temperatures as compared to other semiconductor host materials such as Si and GaAs. 1540nm optical emission in Er- doped waveguide has also been demonstrated using a 365nm light emitting diode as the optical pumping source. UV pumping above the GaN bandgap....9 eV In Table 2 - 1, GaN is the semiconductor material with the largest bandgap (SiO2 is not a semiconductor), which has proven to be an accomplished host of erbium, with reports of fabrication of light- emitting diodes operating in the visible...

Wang, Qian

2012-05-31T23:59:59.000Z

128

Commercial Lighting  

Broader source: Energy.gov [DOE]

Commercial lighting accounts for more than 20 percent of total commercial building energy use. The Energy Department works to reduce lighting energy use through research and deployment.

129

Gallium Lighting, LLC, Accepts Inaugural Position on the Industry Advisory Board of UC-Light Center to Help Bring Wireless Data  

E-Print Network [OSTI]

Gallium Lighting, LLC, Accepts Inaugural Position on the Industry Advisory Board of UC-Light Center to Help Bring Wireless Data Communications Capabilities to LED Lights Fayetteville, GA ­ February 10, 2011 ­Gallium Lighting, LLC, announced today it has accepted an inaugural position

130

Investigation of the GaN-on-GaAs interface for vertical power device applications  

SciTech Connect (OSTI)

GaN layers were grown onto (111) GaAs by molecular beam epitaxy. Minimal band offset between the conduction bands for GaN and GaAs materials has been suggested in the literature raising the possibility of using GaN-on-GaAs for vertical power device applications. I-V and C-V measurements of the GaN/GaAs heterostructures however yielded a rectifying junction, even when both sides of the junction were heavily doped with an n-type dopant. Transmission electron microscopy analysis further confirmed the challenge in creating a GaN/GaAs Ohmic interface by showing a large density of dislocations in the GaN layer and suggesting roughening of the GaN/GaAs interface due to etching of the GaAs by the nitrogen plasma, diffusion of nitrogen or melting of Ga into the GaAs substrate.

Möreke, Janina, E-mail: janina.moereke@bristol.ac.uk; Uren, Michael J.; Kuball, Martin [H.H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Novikov, Sergei V.; Foxon, C. Thomas [Department of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Hosseini Vajargah, Shahrzad; Wallis, David J.; Humphreys, Colin J. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Haigh, Sarah J. [Super STEM Laboratory, STFC Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD (United Kingdom); School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Al-Khalidi, Abdullah; Wasige, Edward; Thayne, Iain [School of Engineering, University of Glasgow, Rankine Bldg, Oakfield Avenue, Glasgow G12 8LT (United Kingdom)

2014-07-07T23:59:59.000Z

131

Composition and Interface Analysis of InGaN/GaN Multiquantum...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Analysis of InGaNGaN Multiquantum-Wells on GaN Substrates Using Atom Probe Tomography. Composition and Interface Analysis of InGaNGaN Multiquantum-Wells on GaN...

132

Evaluation of the two-photon absorption characteristics of GaSb/GaAs quantum rings  

SciTech Connect (OSTI)

The optical parameters describing the sub-bandgap response of GaSb/GaAs quantum rings solar cells have been obtained from photocurrent measurements using a modulated pseudo-monochromatic light source in combination with a second, continuous photo-filling source. By controlling the charge state of the quantum rings, the photoemission cross-sections describing the two-photon sub-bandgap transitions could be determined independently. Temperature dependent photo-response measurements also revealed that the barrier for thermal hole emission from the quantum rings is significantly below the quantum ring localisation energy. The temperature dependence of the sub-bandgap photo-response of the solar cell is also described in terms of the photo- and thermal-emission characteristics of the quantum rings.

Wagener, M. C.; Botha, J. R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Carrington, P. J. [Department of Electronic and Electrical Engineering, University College London, London (United Kingdom); Krier, A. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

2014-07-28T23:59:59.000Z

133

Deposition of CVD diamond onto GaN P.W. May a,*, H.Y. Tsai b  

E-Print Network [OSTI]

of the polycrystalline diamond surface would prevent light from leaking out of the GaN layer and channel it to the endsDeposition of CVD diamond onto GaN P.W. May a,*, H.Y. Tsai b , W.N. Wang c , J.A. Smith a a School performed to deposit continuous layers of CVD diamond onto epitaxial GaN films. Such diamond coatings would

Bristol, University of

134

Improved electrical properties of wafer-bonded p-GaAs/n-InP interfaces with sulfide passivation  

E-Print Network [OSTI]

subcells InGaAsP, InGaAs via direct wafer bonding.8 In order to monolithically interconnect between the top materials, enable increased conversion efficiency due to the higher absorption efficiency obtained from. The additional layer reduces the incident light inten- sity because of the free carrier absorption. A wafer

Atwater, Harry

135

Influence of GaAs surface termination on GaSb/GaAs quantum dot structure and band offsets  

SciTech Connect (OSTI)

We have investigated the influence of GaAs surface termination on the nanoscale structure and band offsets of GaSb/GaAs quantum dots (QDs) grown by molecular-beam epitaxy. Transmission electron microscopy reveals both coherent and semi-coherent clusters, as well as misfit dislocations, independent of surface termination. Cross-sectional scanning tunneling microscopy and spectroscopy reveal clustered GaSb QDs with type I band offsets at the GaSb/GaAs interfaces. We discuss the relative influences of strain and QD clustering on the band offsets at GaSb/GaAs interfaces.

Zech, E. S.; Chang, A. S.; Martin, A. J.; Canniff, J. C.; Millunchick, J. M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Lin, Y. H. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)] [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Goldman, R. S. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)

2013-08-19T23:59:59.000Z

136

La ville comme lieu d'mergence de nouvelles formes d'urbanit. Cas des quartiers rsidentiels de la ville de Constantine  

E-Print Network [OSTI]

La ville comme lieu d'émergence de nouvelles formes d'urbanité. Cas des quartiers résidentiels de supprime le monopole des communes sur le patrimoine foncier et autorise la création des lotissements par l;Mais, si l'Etat ne dispose plus des droits absolus sur la gestion des sols, il restera toujours l

Boyer, Edmond

137

High-performance broadband optical coatings on InGaN/GaN solar cells for multijunction device integration  

SciTech Connect (OSTI)

We demonstrate InGaN/GaN multiple quantum well solar cells grown by metalorganic chemical vapor deposition on a bulk (0001) substrate with high-performance broadband optical coatings to improve light absorption. A front-side anti-reflective coating and a back-side dichroic mirror were designed to minimize front surface reflections across a broad spectral range and maximize rear surface reflections only in the spectral range absorbed by the InGaN, making the cells suitable for multijunction solar cell integration. Application of optical coatings increased the peak external quantum efficiency by 56% (relative) and conversion efficiency by 37.5% (relative) under 1 sun AM0 equivalent illumination.

Young, N. G., E-mail: ngyoung@engineering.ucsb.edu; Farrell, R. M.; Iza, M.; Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Perl, E. E.; Keller, S. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Bowers, J. E.; Nakamura, S.; DenBaars, S. P. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

2014-04-21T23:59:59.000Z

138

C. Wetzel et al MRS Internet J. Nitride Semicond. Res. 10, 2 (2005) 1 Development of High Power Green Light Emitting Diode Chips  

E-Print Network [OSTI]

Power Green Light Emitting Diode Chips C. Wetzel and T. Detchprohm Future Chips Constellation Abstract The development of high emission power green light emitting diodes chips using GaInN/GaN multi production-scale implementation of this green LED die process. Keywords: nitrides, light emitting diode

Wetzel, Christian M.

139

Smart Lighting Controller!! Smart lighting!  

E-Print Network [OSTI]

1! Smart Lighting Controller!! #12;2! Smart lighting! No need to spend energy lighting the room if://blogs.stthomas.edu/realestate/2011/01/24/residential-real-estate-professionals-how-do-you- develop feedback! There is a connection between the output and the input! Therefore forces inputs to same voltage

Anderson, Betty Lise

140

Plasmonic Nanostructure Design for Efficient Light Coupling into Solar Cells  

E-Print Network [OSTI]

Plasmonic Nanostructure Design for Efficient Light Coupling into Solar Cells Vivian E. Ferry, Luke in thin film solar cells. In particular, the ability of plasmonic structures to localize light sunlight into guided modes in thin film Si and GaAs plasmonic solar cells whose back interface is coated

Atwater, Harry

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

X-ray diffraction analysis and scanning micro-Raman spectroscopy of structural irregularities and strains deep inside the multilayered InGaN/GaN heterostructure  

SciTech Connect (OSTI)

High-resolution X-ray diffraction analysis and scanning confocal Raman spectroscopy are used to study the spatial distribution of strains in the In{sub x}Ga{sub 1-x}N/GaN layers and structural quality of these layers in a multilayered light-emitting diode structure produced by metal-organic chemical vapor deposition onto (0001)-oriented sapphire substrates. It is shown that elastic strains almost completely relax at the heterointerface between the thick GaN buffer layer and In{sub x}Ga{sub 1-x}N/GaN buffer superlattice. It is established that the GaN layers in the superlattice are in a stretched state, whereas the alloy layers are in a compressed state. In magnitude, the stretching strains in the GaN layers are lower than the compressive strains in the InGaN layers. It is shown that, as compared to the buffer layers, the layers of the superlattice contain a smaller number of dislocations and the distribution of dislocations is more randomly disordered. In micro-Raman studies on scanning through the thickness of the multilayered structure, direct evidence is obtained for the asymmetric gradient distributions of strains and crystal imperfections of the epitaxial nitride layers along the direction of growth. It is shown that the emission intensity of the In{sub x}Ga{sub 1-x}N quantum well is considerably (more than 30 times) higher than the emission intensity of the GaN barrier layers, suggesting the high efficiency of trapping of charge carriers by the quantum well.

Strelchuk, V. V., E-mail: Strelch@isp.kiev.ua; Kladko, V. P.; Avramenko, E. A.; Kolomys, O. F.; Safryuk, N. V.; Konakova, R. V. [National Academy of Sciences of Ukraine, Lashkaryov Institute of Semiconductor Physics (Ukraine); Yavich, B. S., E-mail: byavich@soptel.ru [ZAO Svetlana-Optoelectronics (Russian Federation); Valakh, M. Ya.; Machulin, V. F.; Belyaev, A. E. [National Academy of Sciences of Ukraine, Lashkaryov Institute of Semiconductor Physics (Ukraine)

2010-09-15T23:59:59.000Z

142

Commercial Lighting and LED Lighting Incentives  

Broader source: Energy.gov [DOE]

Incentives for energy efficient commercial lighting equipment as well as commercial LED lighting equipment are available to businesses under the Efficiency Vermont Lighting and LED Lighting...

143

Nanostructured High Performance Ultraviolet and Blue Light Emitting Diodes for Solid State Lighting  

SciTech Connect (OSTI)

We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the second 12 month contract period include (i) new means of synthesizing AlGaN and InN quantum dots by droplet heteroepitaxy, (ii) synthesis of AlGaInN nanowires as building blocks for GaN-based microcavity devices, (iii) progress towards direct epitaxial alignment of the dense arrays of nanowires, (iv) observation and measurements of stimulated emission in dense InGaN nanopost arrays, (v) design and fabrication of InGaN photonic crystal emitters, and (vi) observation and measurements of enhanced fluorescence from coupled quantum dot and plasmonic nanostructures. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

Arto V. Nurmikko; Jung Han

2005-09-30T23:59:59.000Z

144

Max Tech Appliance Design: Potential for Maximizing U.S. Energy Savings through Standards  

E-Print Network [OSTI]

Compressors Comm. Storage Water Heaters (gas) Street LightsHeaters Comm. Storage Water Heaters (elec. ) )TorchieresCompressors Comm. Storage Water Heaters … Street Lights Low-

Garbesi, Karina

2011-01-01T23:59:59.000Z

145

Max Tech and Beyond: Maximizing Appliance and Equipment Efficiency by Design  

E-Print Network [OSTI]

Torchieres Comm. Storage Water Heaters (elec. ) Res. GasLights Comm. Storage Water Heaters (gas) Air CompressorsCompressors Comm. Storage Water Heaters (gas) Street Lights

Desroches, Louis-Benoit

2012-01-01T23:59:59.000Z

146

Lighting Renovations  

Broader source: Energy.gov [DOE]

When undertaking a lighting renovation in a Federal building, daylighting is the primary renewable energy opportunity. Photovoltaics (PV) also present an excellent opportunity. While this guide...

147

Cerenkov Light  

ScienceCinema (OSTI)

The bright blue glow from nuclear reactors is Cerenkov light. Karl Slifer describes how nuclear physicists can use this phenomenon to study the nucleus of the atom.

Slifer, Karl

2014-05-22T23:59:59.000Z

148

Cerenkov Light  

SciTech Connect (OSTI)

The bright blue glow from nuclear reactors is Cerenkov light. Karl Slifer describes how nuclear physicists can use this phenomenon to study the nucleus of the atom.

Slifer, Karl

2013-06-13T23:59:59.000Z

149

Characterisation of Ga-coated and Ga-brazed aluminium  

SciTech Connect (OSTI)

This work is devoted to the brazing of aluminium using liquid gallium. Gallium was deposited on aluminium samples at {approx} 50 Degree-Sign C using a liquid gallium 'polishing' technique. Brazing was undertaken for 30 min at 500 Degree-Sign C in air. EDS (Energy Dispersive X-ray Spectroscopy) and AES (Auger Electron Spectroscopy) characterisation of Ga-coated samples has shown that the Ga surface layer thickness is of ten (or a few tens of) nanometres. Furthermore, aluminium oxide layer (Al{sub 2}O{sub 3}) was shown to be 'descaled' during Ga deposition, which ensures good conditions for further brazing. Cross-section examination of Ga-coated samples shows that liquid gallium penetrates into the aluminium grain boundaries during deposition. The thickness of the grain boundary gallium film was measured using an original EDS technique and is found to be of a few tens of nanometres. The depth of gallium grain boundary penetration is about 300 {mu}m at the deposition temperature. The fracture stress of the brazed joints was measured from tensile tests and was determined to be 33 MPa. Cross-section examination of brazed joints shows that gallium has fully dissolved into the bulk and that the joint is really autogenous. - Highlights: Black-Right-Pointing-Pointer Aluminium can be brazed using liquid gallium deposited by a 'polishing' technique. Black-Right-Pointing-Pointer The aluminium oxide layer is 'descaled' during liquid Ga 'polishing' deposition. Black-Right-Pointing-Pointer EDS can be used for determination of surface and grain boundary Ga film thickness. Black-Right-Pointing-Pointer The surface and grain boundary Ga film thickness is of a few tens of nm. Black-Right-Pointing-Pointer Surface and grain boundary gallium dissolves in the bulk during brazing.

Ferchaud, E. [Universite de Nantes, Polytech'Nantes, Laboratoire Genie des Materiaux et Procedes Associes, Rue Christian Pauc, 44306 Nantes Cedex 3 (France); Christien, F., E-mail: frederic.christien@univ-nantes.fr [Universite de Nantes, Polytech'Nantes, Laboratoire Genie des Materiaux et Procedes Associes, Rue Christian Pauc, 44306 Nantes Cedex 3 (France); Barnier, V. [Ecole Nationale Superieure des Mines, MPI, CNRS UMR5146, Centre SMS, 158 Cours Fauriel, 42023 Saint Etienne (France); Paillard, P. [Universite de Nantes, Polytech'Nantes, Laboratoire Genie des Materiaux et Procedes Associes, Rue Christian Pauc, 44306 Nantes Cedex 3 (France)

2012-05-15T23:59:59.000Z

150

Nanoengineering for solid-state lighting.  

SciTech Connect (OSTI)

This report summarizes results from a 3-year Laboratory Directed Research and Development project performed in collaboration with researchers at Rensselaer Polytechnic Institute. Our collaborative effort was supported by Sandia's National Institute for Nanoengineering and focused on the study and application of nanoscience and nanoengineering concepts to improve the efficiency of semiconductor light-emitting diodes for solid-state lighting applications. The project explored LED efficiency advances with two primary thrusts: (1) the study of nanoscale InGaN materials properties, particularly nanoscale crystalline defects, and their impact on internal quantum efficiency, and (2) nanoscale engineering of dielectric and metal materials and integration with LED heterostructures for enhanced light extraction efficiency.

Schubert, E. Fred (Rensselaer Polytechnic Institute,Troy, NY); Koleske, Daniel David; Wetzel, Christian (Rensselaer Polytechnic Institute,Troy, NY); Lee, Stephen Roger; Missert, Nancy A.; Lin, Shawn-Yu (Rensselaer Polytechnic Institute,Troy, NY); Crawford, Mary Hagerott; Fischer, Arthur Joseph

2009-09-01T23:59:59.000Z

151

Localization of degradation in InP/InGaAsP mushroom stripe lasers  

SciTech Connect (OSTI)

The rapid degradation observed in InP/InGaAsP mushroom stripe lasers covered with phosphosilicate glass (PSG) was investigated by comparing the light-current characteristics as a function of the preparation technique. We were able to show that the PSG-covering layer is not the reason for the rapid degradation. By inspecting the light-current characteristics before and after degradation and by additional underetching the laser structure after degradation we were able to localize the degraded regions on the open side walls of the InGaAsP active layer.

Jung, H.; Marschall, P.

1987-07-13T23:59:59.000Z

152

Contact Information Updated: June 17, 2014 Co. Comm/Sealer Address Telephone/Fax General County E-Mail/Office Hours  

E-Print Network [OSTI]

Contact Information Updated: June 17, 2014 Co. Comm/Sealer Address Telephone/Fax General County E-F: 8-5 El Centro, 92243-2850 Inyo/Mono County Srvs Bldg, 207 W South St (760) 873-7860 inyomonoag-6300 agcomm@co.kern.ca.us Ruben Arroyo Bakersfield, 93307-2857 (661) 868-6301 M-F: 8-5 Kings 680 N Campus

153

Amber light-emitting diode comprising a group III-nitride nanowire active region  

DOE Patents [OSTI]

A temperature stable (color and efficiency) III-nitride based amber (585 nm) light-emitting diode is based on a novel hybrid nanowire-planar structure. The arrays of GaN nanowires enable radial InGaN/GaN quantum well LED structures with high indium content and high material quality. The high efficiency and temperature stable direct yellow and red phosphor-free emitters enable high efficiency white LEDs based on the RGYB color-mixing approach.

Wang, George T.; Li, Qiming; Wierer, Jr., Jonathan J.; Koleske, Daniel

2014-07-22T23:59:59.000Z

154

Broadband light-emitting diode  

DOE Patents [OSTI]

A broadband light-emitting diode. The broadband light-emitting diode (LED) comprises a plurality of III-V compound semiconductor layers grown on a semiconductor substrate, with the semiconductor layers including a pair of cladding layers sandwiched about a strained-quantum-well active region having a plurality of different energy bandgaps for generating light in a wavelength range of about 1.3-2 .mu.m. In one embodiment of the present invention, the active region may comprise a first-grown quantum-well layer and a last-grown quantum-well layer that are oppositely strained; whereas in another embodiment of the invention, the active region is formed from a short-period superlattice structure (i.e. a pseudo alloy) comprising alternating thin layers of InGaAs and InGaAlAs. The use a short-period superlattice structure for the active region allows different layers within the active region to be simply and accurately grown by repetitively opening and closing one or more shutters in an MBE growth apparatus to repetitively switch between different growth states therein. The broadband LED may be formed as either a surface-emitting LED or as an edge-emitting LED for use in applications such as chemical sensing, fiber optic gyroscopes, wavelength-division-multiplexed (WDM) fiber-optic data links, and WDM fiber-optic sensor networks for automobiles and aircraft.

Fritz, Ian J. (Albuquerque, NM); Klem, John F. (Sandia Park, NM); Hafich, Michael J. (Albuquerque, NM)

1998-01-01T23:59:59.000Z

155

Broadband light-emitting diode  

DOE Patents [OSTI]

A broadband light-emitting diode is disclosed. The broadband light-emitting diode (LED) comprises a plurality of III-V compound semiconductor layers grown on a semiconductor substrate, with the semiconductor layers including a pair of cladding layers sandwiched about a strained-quantum-well active region having a plurality of different energy bandgaps for generating light in a wavelength range of about 1.3--2 {micro}m. In one embodiment of the present invention, the active region may comprise a first-grown quantum-well layer and a last-grown quantum-well layer that are oppositely strained; whereas in another embodiment of the invention, the active region is formed from a short-period superlattice structure (i.e. a pseudo alloy) comprising alternating thin layers of InGaAs and InGaAlAs. The use a short-period superlattice structure for the active region allows different layers within the active region to be simply and accurately grown by repetitively opening and closing one or more shutters in an MBE growth apparatus to repetitively switch between different growth states therein. The broadband LED may be formed as either a surface-emitting LED or as an edge-emitting LED for use in applications such as chemical sensing, fiber optic gyroscopes, wavelength-divisionmultiplexed (WDM) fiber-optic data links, and WDM fiber-optic sensor networks for automobiles and aircraft. 10 figs.

Fritz, I.J.; Klem, J.F.; Hafich, M.J.

1998-07-14T23:59:59.000Z

156

Properties of H, O and C in GaN  

SciTech Connect (OSTI)

The electrical properties of the light ion impurities H, O and C in GaN have been examined in both as-grown and implanted material. H is found to efficiently passivate acceptors such as Mg, Ca and C. Reactivation occurs at {ge} 450 C and is enhanced by minority carrier injection. The hydrogen does not leave the GaN crystal until > 800 C, and its diffusivity is relatively high ({approximately} 10{sup {minus}11} cm{sup 2}/s) even at low temperatures (< 200 C) during injection by wet etching, boiling in water or plasma exposure. Oxygen shows a low donor activation efficiency when implanted into GaN, with an ionization level of 30--40 meV. It is essentially immobile up to 1,100 C. Carbon can produce low p-type levels (3 {times} 10{sup 17} cm{sup {minus}3}) in GaN during MOMBE, although there is some evidence it may also create n-type conduction in other nitrides.

Pearton, S.J.; Abernathy, C.R.; Lee, J.W. [Univ. of Florida, Gainesville, FL (United States)] [and others

1996-04-01T23:59:59.000Z

157

Intense terahertz emission from molecular beam epitaxy-grown GaAs/GaSb(001)  

SciTech Connect (OSTI)

Intense terahertz (THz) electromagnetic wave emission was observed in undoped GaAs thin films deposited on (100) n-GaSb substrates via molecular beam epitaxy. GaAs/n-GaSb heterostructures were found to be viable THz sources having signal amplitude 75% that of bulk p-InAs. The GaAs films were grown by interruption method during the growth initiation and using various metamorphic buffer layers. Reciprocal space maps revealed that the GaAs epilayers are tensile relaxed. Defects at the i-GaAs/n-GaSb interface were confirmed by scanning electron microscope images. Band calculations were performed to infer the depletion region and electric field at the i-GaAs/n-GaSb and the air-GaAs interfaces. However, the resulting band calculations were found to be insufficient to explain the THz emission. The enhanced THz emission is currently attributed to a piezoelectric field induced by incoherent strain and defects.

Sadia, Cyril P.; Laganapan, Aleena Maria; Agatha Tumanguil, Mae; Estacio, Elmer; Somintac, Armando; Salvador, Arnel [National Institute of Physics, University of the Philippines Diliman, Quezon City 1101 (Philippines); Que, Christopher T. [Physics Department, De La Salle University, 2401 Taft Avenue, Manila 1004 (Philippines); Yamamoto, Kohji; Tani, Masahiko [Research Center for Development of Far-Infrared Region, University of Fukui, Fukui 910-8507 (Japan)

2012-12-15T23:59:59.000Z

158

GA Solar | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of Inspector GeneralDepartmentAUDIT REPORTOpen EnergyBoard" form. To create aGA SNC Solar Jump to:GA-Solar

159

Plasmonic nanoparticle enhanced photocurrent in GaN/InGaN/GaN quantum well solar cells  

E-Print Network [OSTI]

Plasmonic nanoparticle enhanced photocurrent in GaN/InGaN/GaN quantum well solar cells Imogen M of Applied Physics, California Institute of Technology, Pasadena, California 91125, USA 2 Semiconductor Nanoscience Institute, California Institute of Technology, Pasadena, California 91125, USA Received 26

Atwater, Harry

160

Native point defects in GaSb  

SciTech Connect (OSTI)

We have applied positron annihilation spectroscopy to study native point defects in Te-doped n-type and nominally undoped p-type GaSb single crystals. The results show that the dominant vacancy defect trapping positrons in bulk GaSb is the gallium monovacancy. The temperature dependence of the average positron lifetime in both p- and n-type GaSb indicates that negative ion type defects with no associated open volume compete with the Ga vacancies. Based on comparison with theoretical predictions, these negative ions are identified as Ga antisites. The concentrations of these negatively charged defects exceed the Ga vacancy concentrations nearly by an order of magnitude. We conclude that the Ga antisite is the native defect responsible for p-type conductivity in GaSb single crystals.

Kujala, J.; Segercrantz, N.; Tuomisto, F.; Slotte, J. [Department of Applied Physics, Aalto University School of Science, P.O. Box 14100, FI-00076 AALTO (Finland)

2014-10-14T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Epitaxial Growth of GaN-based LEDs on Simple Sacrificial Substrates  

SciTech Connect (OSTI)

The objective of this project is to produce alternative substrate technologies for GaN-based LEDs by developing an ALD interlayer of Al{sub 2}O{sub 3} on sacrificial substrates such as ZnO and Si. A sacrificial substrate is used for device growth that can easily be removed using a wet chemical etchant leaving only the thin GaN epi-layer. After substrate removal, the GaN LED chip can then be mounted in several different ways to a metal heat sink/reflector and light extraction techniques can then be applied to the chip and compared for performance. Success in this work will lead to high efficiency LED devices with a simple low cost fabrication method and high product yield as stated by DOE goals for its solid state lighting portfolio.

Ian Ferguson; Chris Summers

2009-12-31T23:59:59.000Z

162

New GaInP/GaAs/GaInAs, Triple-Bandgap, Tandem Solar Cell for High-Efficiency Terrestrial Concentrator Systems  

SciTech Connect (OSTI)

GaInP/GaAs/GaInAs three-junction cells are grown in an inverted configuration on GaAs, allowing high quality growth of the lattice matched GaInP and GaAs layers before a grade is used for the 1-eV GaInAs layer. Using this approach an efficiency of 37.9% was demonstrated.

Kurtz, S.; Wanlass, M.; Kramer, C.; Young, M.; Geisz, J.; Ward, S.; Duda, A.; Moriarty, T.; Carapella, J.; Ahrenkiel, P.; Emery. K.; Jones, K.; Romero, M.; Kibbler, A.; Olson, J.; Friedman, D.; McMahon, W.; Ptak, A.

2005-11-01T23:59:59.000Z

163

Heteroepitaxial growth and surface structure of L1{sub 0}-MnGa(111) ultra-thin films on GaN(0001)  

SciTech Connect (OSTI)

L1{sub 0}-structured MnGa(111) ultra-thin films were heteroepitaxially grown on GaN(0001) under lightly Mn-rich conditions using molecular beam epitaxy. Room-temperature scanning tunneling microscopy (STM) investigations reveal smooth terraces and angular step edges, with the surface structure consisting primarily of a 2 × 2 reconstruction along with small patches of 1 × 2. Theoretical calculations were carried out using density functional theory, and the simulated STM images were calculated using the Tersoff-Hamman approximation, revealing that a stoichiometric 1 × 2 and a Mn-rich 2 × 2 surface structure give the best agreement with the observed experimental images.

Mandru, Andrada-Oana; Wang, Kangkang; Cooper, Kevin; Ingram, David C.; Smith, Arthur R. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States)] [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Garcia Diaz, Reyes; Takeuchi, Noboru [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States) [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada Baja California, Codigo Postal 22800 (Mexico); Haider, Muhammad [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States) [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran, 31261 (Saudi Arabia)

2013-10-14T23:59:59.000Z

164

Beta decay of Ga-62  

E-Print Network [OSTI]

from the ex- perimental ft value for a 01?01 b decay between analog states with the relation @3# 0556-2813/2003/68~1!/015501~6!/$20.00 68 015501- of 62Ga . Hardy, V. E. Mayes, R. G. Neilson, M. Sanchez-Vega, and R. E. Tribble y, College Station...

Hyman, BC; Iacob, VE; Azhari, A.; Gagliardi, Carl A.; Hardy, John C.; Mayes, VE; Neilson, RG; Sanchez-Vega, M.; Tang, X.; Trache, L.; Tribble, Robert E.

2003-01-01T23:59:59.000Z

165

VISIBLE AND INFRARED RARE-EARTH ACTIVATED ELECTROLUMINESCENCE FROM ERBIUM DOPED GaN  

E-Print Network [OSTI]

. At the same time novel work is being conducted using rare earth elements as sources of light emission. Results. III-V semiconductors doped with rare-earth elements have also been used10VISIBLE AND INFRARED RARE-EARTH ACTIVATED ELECTROLUMINESCENCE FROM ERBIUM DOPED GaN M. Garter*, R

Steckl, Andrew J.

166

Monolithic integration of InGaN segments emitting in the blue, green, and red spectral range in single ordered nanocolumns  

SciTech Connect (OSTI)

This work reports on the selective area growth by plasma-assisted molecular beam epitaxy and characterization of InGaN/GaN nanocolumnar heterostructures. The optimization of the In/Ga and total III/V ratios, as well as the growth temperature, provides control on the emission wavelength, either in the blue, green, or red spectral range. An adequate structure tailoring and monolithic integration in a single nanocolumnar heterostructure of three InGaN portions emitting in the red-green-blue colors lead to white light emission.

Albert, S.; Bengoechea-Encabo, A.; Sanchez-Garcia, M. A.; Calleja, E. [ISOM and Dept. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)] [ISOM and Dept. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Kong, X.; Trampert, A. [Paul-Drude-Institut fuer Festkoeperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)] [Paul-Drude-Institut fuer Festkoeperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

2013-05-06T23:59:59.000Z

167

Effect of buffer structures on AlGaN/GaN high electron mobility transistor reliability  

SciTech Connect (OSTI)

AlGaN/GaN high electron mobility transistors (HEMTs) with three different types of buffer layers, including a GaN/AlGaN composite layer, or 1 or 2 lm GaN thick layers, were fabricated and their reliability compared. The HEMTs with the thick GaN buffer layer showed the lowest critical voltage (Vcri) during off-state drain step-stress, but this was increased by around 50% and 100% for devices with the composite AlGaN/GaN buffer layers or thinner GaN buffers, respectively. The Voff - state for HEMTs with thin GaN and composite buffers were 100 V, however, this degraded to 50 60V for devices with thick GaN buffers due to the difference in peak electric field near the gate edge. A similar trend was observed in the isolation breakdown voltage measurements, with the highest Viso achieved based on thin GaN or composite buffer designs (600 700 V), while a much smaller Viso of 200V was measured on HEMTs with the thick GaN buffer layers. These results demonstrate the strong influence of buffer structure and defect density on AlGaN/GaN HEMT performance and reliability.

Liu, L. [University of Florida, Gainesville; Xi, Y. Y. [University of Florida, Gainesville; Ren, F. [University of Florida; Pearton, S. J. [University of Florida; Laboutin, O. [Kopin Corporation, Taunton, MA; Cao, Yu [Kopin Corporation, Taunton, MA; Johnson, Wayne J. [Kopin Corporation, Taunton, MA; Kravchenko, Ivan I [ORNL

2012-01-01T23:59:59.000Z

168

Light Computing  

E-Print Network [OSTI]

A configuration of light pulses is generated, together with emitters and receptors, that allows computing. The computing is extraordinarily high in number of flops per second, exceeding the capability of a quantum computer for a given size and coherence region. The emitters and receptors are based on the quantum diode, which can emit and detect individual photons with high accuracy.

Gordon Chalmers

2006-10-13T23:59:59.000Z

169

High-field electroluminescence in semiconductor tunnel junctions with a Mn-doped GaAs layer  

SciTech Connect (OSTI)

We investigated high-field electroluminescence (EL) in semiconductor tunnel junctions with a Mn-doped GaAs layer (here, referred to as GaAs:Mn). Besides the band-gap emission of GaAs, the EL spectra show visible light emissions with two peaks at 1.94?eV and 2.19?eV, which are caused by d-d transitions of the Mn atoms excited by hot electrons. The threshold voltages for band-gap and visible light EL in the tunnel junctions with a GaAs:Mn electrode are 1.3?V higher than those of GaAs:Mn excited by hot holes in reserve biased p{sup +}-n junctions, which is consistent with the hot carrier transport in the band profiles of these structures. Our EL results at room temperature show that the electron temperature in GaAs:Mn can be as high as ?700?K for a low input electrical power density of 0.4?W/cm{sup 2}, while the lattice temperature of the GaAs:Mn layer can be kept at 340?K.

Hai, Pham Nam [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-0033 (Japan); Yatsui, Takashi; Ohtsu, Motoichi; Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nanophotonics Research Center, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2014-09-21T23:59:59.000Z

170

InGaAsN/GaAs heterojunction for multi-junction solar cells  

DOE Patents [OSTI]

An InGaAsN/GaAs semiconductor p-n heterojunction is disclosed for use in forming a 0.95-1.2 eV bandgap photodetector with application for use in high-efficiency multi-junction solar cells. The InGaAsN/GaAs p-n heterojunction is formed by epitaxially growing on a gallium arsenide (GaAs) or germanium (Ge) substrate an n-type indium gallium arsenide nitride (InGaAsN) layer having a semiconductor alloy composition In.sub.x Ga.sub.1-x As.sub.1-y N.sub.y with 0GaAs layer, with the InGaAsN and GaAs layers being lattice-matched to the substrate. The InGaAsN/GaAs p-n heterojunction can be epitaxially grown by either molecular beam epitaxy (MBE) or metalorganic chemical vapor deposition (MOCVD). The InGaAsN/GaAs p-n heterojunction provides a high open-circuit voltage of up to 0.62 volts and an internal quantum efficiency of >70%.

Kurtz, Steven R. (Albuquerque, NM); Allerman, Andrew A. (Albuquerque, NM); Klem, John F. (Albuquerque, NM); Jones, Eric D. (Edgewood, NM)

2001-01-01T23:59:59.000Z

171

NANOSTRUCTURED HIGH PERFORMANCE ULTRAVIOLET AND BLUE LIGHT EMITTING DIODES FOR SOLID STATE LIGHTING  

SciTech Connect (OSTI)

We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the first 12 month contract period include (1) new means of synthesizing zero- and one-dimensional GaN nanostructures, (2) establishment of the building blocks for making GaN-based microcavity devices, and (3) demonstration of top-down approach to nano-scale photonic devices for enhanced spontaneous emission and light extraction. These include a demonstration of eight-fold enhancement of the external emission efficiency in new InGaN QW photonic crystal structures. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

Arto V. Nurmikko; Jung Han

2004-10-01T23:59:59.000Z

172

Infrared light sources with semimetal electron injection  

DOE Patents [OSTI]

An infrared light source is disclosed that comprises a layered semiconductor active region having a semimetal region and at least one quantum-well layer. The semimetal region, formed at an interface between a GaAsSb or GalnSb layer and an InAsSb layer, provides electrons and holes to the quantum-well layer to generate infrared light at a predetermined wavelength in the range of 2-6 .mu.m. Embodiments of the invention can be formed as electrically-activated light-emitting diodes (LEDs) or lasers, and as optically-pumped lasers. Since the active region is unipolar, multiple active regions can be stacked to form a broadband or multiple-wavelength infrared light source.

Kurtz, Steven R. (Albuquerque, NM); Biefeld, Robert M. (Albuquerque, NM); Allerman, Andrew A. (Albuquerque, NM)

1999-01-01T23:59:59.000Z

173

Conference 5739, SPIE International Symposium Integrated Optoelectronic Devices, 22-27 Jan 2005, San Jose, CA Development of high power green light emitting diode dies in  

E-Print Network [OSTI]

, San Jose, CA Development of high power green light emitting diode dies in piezoelectric Ga in green light emitting diodes is one of the big challenges towards all-solid- state lighting. The prime,3], and commercialization [4,5] of high brightness light emitting diodes LEDs has led to a 1.82 Billion-$/year world market

Wetzel, Christian M.

174

Influence of growth temperature and temperature ramps on deep level defect incorporation in m-plane GaN  

SciTech Connect (OSTI)

The dependence of deep level defect incorporation in m-plane GaN films grown by metal-organic chemical vapor deposition on bulk m-plane GaN substrates as a function of growth temperature (T{sub g}) and T{sub g} ramping method was investigated using deep level optical spectroscopy. Understanding the influence of T{sub g} on GaN deep level incorporation is important for InGaN/GaN multi-quantum well (MQW) light emitting diodes (LEDs) and laser diodes (LDs) because GaN quantum barrier (QB) layers are grown much colder than thin film GaN to accommodate InGaN QW growth. Deep level spectra of low T{sub g} (800?°C) GaN films grown under QB conditions were compared to deep level spectra of high T{sub g} (1150?°C) GaN. Reducing T{sub g}, increased the defect density significantly (>50×) through introduction of emergent deep level defects at 2.09?eV and 2.9?eV below the conduction band minimum. However, optimizing growth conditions during the temperature ramp when transitioning from high to low T{sub g} substantially reduced the density of these emergent deep levels by approximately 40%. The results suggest that it is important to consider the potential for non-radiative recombination in QBs of LED or LD active regions, and tailoring the transition from high T{sub g} GaN growth to active layer growth can mitigate such non-radiative channels.

Armstrong, A. M., E-mail: aarmstr@sandia.gov [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Kelchner, K. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)] [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Nakamura, S.; DenBaars, S. P. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States) [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Materials Department, University of California, Santa Barbara, California 93106 (United States); Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States)] [Materials Department, University of California, Santa Barbara, California 93106 (United States)

2013-12-02T23:59:59.000Z

175

High Efficiency m-plane LEDs on Low Defect Density Bulk GaN Substrates  

SciTech Connect (OSTI)

Solid-state lighting is a key technology for reduction of energy consumption in the US and worldwide. In principle, by replacing standard incandescent bulbs and other light sources with sources based on light-emitting diodes (LEDs), ultimate energy efficiency can be achieved. The efficiency of LEDs has improved tremendously over the past two decades, however further progress is required for solid- state lighting to reach its full potential. The ability of an LED at converting electricity to light is quantified by its internal quantum efficiency (IQE). The material of choice for visible LEDs is Gallium Nitride (GaN), which is at the basis of blue-emitting LEDs. A key factor limiting the performance of GaN LEDs is the so-called efficiency droop, whereby the IQE of the LED decreases significantly at high current density. Despite decades of research, efficiency droop remains a major issue. Since high-current operation is necessary for practical lighting applications, reducing droop is a major challenge for the scientific community and the LED industry. Our approach to solving the droop issue is the use of newly available low-defect-density bulk GaN non-polar substrates. In contrast to the standard foreign substrates (sapphire, silicon carbide, silicon) used in the industry, we have employed native bulk GaN substrates with very low defect density, thus ensuring exquisite material quality and high IQE. Whereas all commercial LEDs are grown along the c-plane crystal direction of GaN, we have used m-plane non-polar substrates; these drastically modify the physical properties of the LED and enable a reduction of droop. With this approach, we have demonstrated very high IQE performance and low droop. Our results focused on violet and blue LEDs. For these, we have demonstrated very high peak IQEs and current droops of 6% and 10% respectively (up to a high current density of 200A.cm-2). All these results were obtained under electrical operation. These high IQE and low droop values are in line with the program’s milestones. They demonstrate that bulk non-polar GaN substrates represent a disruptive technology for LED performance. Application of this technology to real-world products is feasible, provided that the cost of GaN substrates is compatible with the market’s requirement.

David, Aurelien

2012-10-15T23:59:59.000Z

176

Abstract --This letter presents highly-polarized edge light emitting diodes with high-confinement, strained, multiple  

E-Print Network [OSTI]

power. We characterize InGaAsP MQW ELED devices with different lengths and optical confinement factors that transitions involving the HH band provide gain/absorption to TE polarized light and those involving the LH band provide gain/absorption mostly to TM polarized light, and to a lesser extent to TE light [7

Coldren, Larry A.

177

Lighting Inventory Lighting Theatre and Drama  

E-Print Network [OSTI]

Lighting Inventory Lighting Theatre and Drama Description Totals R.Halls Wells- Metz Light ERS ETC SourceFour 25 25 50 degree ERS Strand Lighting 64 14 24 12 14 36 degree ERS ETC Source Four 15 15 36 degree ERS Strand Lighting 124 60 58 2 4 26 degree ERS ETC SourceFour 2 2 26 degree ERS Strand

Indiana University

178

Color-converting combinations of nanocrystal emitters for warm-white light generation with high color rendering index  

E-Print Network [OSTI]

color rendering index Sedat Nizamoglu, Gulis Zengin, and Hilmi Volkan Demira Department of Electrical 2008 Warm-white light emitting diodes with high color rendering indices are required for the widespreadSe/ZnS core-shell nanocrystals hybridized on InGaN/GaN LEDs for high color rendering index. Three sets

Demir, Hilmi Volkan

179

Temperature-dependent quantum efficiency of Ga(N,As,P) quantum wells  

SciTech Connect (OSTI)

The photoluminescence quantum efficiencies of a series of Ga(N,As,P)/GaP multiple quantum wells are analyzed. The external quantum efficiencies are derived from the absorbed and the emitted light intensities measured using an integrating sphere mounted inside a closed-cycle helium cryostat. By taking into account the device layer sequences as well as internal reflections and reabsorption, the internal quantum efficiencies yield values above 90% for all samples at cryogenic temperatures. The temperature-dependence of the quantum efficiencies as a function of active quantum well layer design reveal the internal interfaces as remaining growth challenge in these heterostructures.

Rosemann, N. W., E-mail: Nils.Rosemann@Physik.Uni-Marburg.de; Metzger, B.; Volz, K.; Chatterjee, S. [Faculty of Physics and Material Sciences Center, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg (Germany)] [Faculty of Physics and Material Sciences Center, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg (Germany); Kunert, B. [NAsP III/V GmbH, Am Knechtacker 19, D-35041 Marburg (Germany)] [NAsP III/V GmbH, Am Knechtacker 19, D-35041 Marburg (Germany); Stolz, W. [Faculty of Physics and Material Sciences Center, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg (Germany) [Faculty of Physics and Material Sciences Center, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg (Germany); NAsP III/V GmbH, Am Knechtacker 19, D-35041 Marburg (Germany)

2013-12-16T23:59:59.000Z

180

Efficient vertical coupling of photodiodes to InGaAsP rib waveguides  

SciTech Connect (OSTI)

We demonstrate vertical integration of InGaAs mesa photodiodes with InGaAsP rib waveguides employing an intermediate optical impedance matching layer. The diode length necessary for 90% light absorption at 1.52 {mu}m wavelength was 42 {mu}m, a threefold reduction in diode length with respect to previous work employing similar waveguides without a matching layer. The quantum efficiency was observed to be almost independent of the optical wavelength and polarization. The influence of spatial transient intensity redistribution effects on these devices is investigated in detail.

Deri, R.J.; Doldissen, W.; Hawkins, R.J.; Bhat, R.; Soole, J.B.D.; Schiavone, L.M.; Seto, M.; Andreadakis, N.; Silberberg, Y.; Koza, M.A. (Bellcore, 331 Newman Springs Road, Red Bank, New Jersey 07701-7040 (USA))

1991-06-17T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Ultra-Thin, Triple-Bandgap GaInP/GaAs/GaInAs Monolithic Tandem Solar Cells  

SciTech Connect (OSTI)

The performance of state-of-the-art, series-connected, lattice-matched (LM), triple-junction (TJ), III-V tandem solar cells could be improved substantially (10-12%) by replacing the Ge bottom subcell with a subcell having a bandgap of {approx}1 eV. For the last several years, research has been conducted by a number of organizations to develop {approx}1-eV, LM GaInAsN to provide such a subcell, but, so far, the approach has proven unsuccessful. Thus, the need for a high-performance, monolithically integrable, 1-eV subcell for TJ tandems has remained. In this paper, we present a new TJ tandem cell design that addresses the above-mentioned problem. Our approach involves inverted epitaxial growth to allow the monolithic integration of a lattice-mismatched (LMM) {approx}1-eV GaInAs/GaInP double-heterostructure (DH) bottom subcell with LM GaAs (middle) and GaInP (top) upper subcells. A transparent GaInP compositionally graded layer facilitates the integration of the LM and LMM components. Handle-mounted, ultra-thin device fabrication is a natural consequence of the inverted-structure approach, which results in a number of advantages, including robustness, potential low cost, improved thermal management, incorporation of back-surface reflectors, and possible reclamation/reuse of the parent crystalline substrate for further cost reduction. Our initial work has concerned GaInP/GaAs/GaInAs tandem cells grown on GaAs substrates. In this case, the 1-eV GaInAs experiences 2.2% compressive LMM with respect to the substrate. Specially designed GaInP graded layers are used to produce 1-eV subcells with performance parameters nearly equaling those of LM devices with the same bandgap (e.g., LM, 1-eV GaInAsP grown on InP). Previously, we reported preliminary ultra-thin tandem devices (0.237 cm{sup 2}) with NREL-confirmed efficiencies of 31.3% (global spectrum, one sun) (1), 29.7% (AM0 spectrum, one sun) (2), and 37.9% (low-AOD direct spectrum, 10.1 suns) (3), all at 25 C. Here, we include recent results of testing similar devices under the concentrated AMO spectrum, and also present the first demonstration of a high-efficiency, ultra-thin GaInP/GaAs/GaInAs tandem cell processed on a flexible kapton handle.

Wanlass, M. W.; Ahrenkiel, S. P.; Albin, D. S.; Carapella, J. J.; Duda, A.; Emery, K.; Geisz, J. F.; Jones, K.; Kurtz, S.; Moriarty, T.; Romero, M. J.

2007-02-01T23:59:59.000Z

182

Impact of electrochemical process on the degradation mechanisms of AlGaN/GaN HEMTs  

E-Print Network [OSTI]

AlGaN/GaN high electron mobility transistors (HEMTs) constitute a new generation of transistors with excellent electrical characteristics and great potential to replace silicon technology in the future, especially in high ...

Gao, Feng, Ph. D. Massachusetts Institute of Technology

2014-01-01T23:59:59.000Z

183

Light Source  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: VegetationEquipment Surfaces and Interfaces Sample6, 2011 LawrenceEfeedstocks and the climateLife a Light

184

Light' Darkness  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: VegetationEquipment Surfaces and Interfaces Sample6, 2011 LawrenceEfeedstocks and the climateLifeLight to

185

Residential Lighting  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 -the Mid-Infrared atEffectquestionnairesU.S. EnergyEnergy EfficiencyLighting

186

Light Water Reactor Sustainability  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

3 Light Water Reactor Sustainability Program ACCOMPLISHMENTS REPORT 2013 Accomplishments Report | Light Water Reactor Sustainability 2 T he mission of the Light Water Reactor...

187

Light Water Reactor Sustainability  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

4 Light Water Reactor Sustainability ACCOMPLISHMENTS REPORT 2014 Accomplishments Report | Light Water Reactor Sustainability 2 T he mission of the Light Water Reactor...

188

Siemens Pittsburgh, PA Novelis Corporation Atlanta, GA  

E-Print Network [OSTI]

Industrial Design ­ Shanghai, China Eaton Corporation ­ Pittsburgh, PA CMU, CTTEC ­ PittsburghSiemens ­ Pittsburgh, PA Novelis Corporation ­ Atlanta, GA Expense

McGaughey, Alan

189

Solar Cells from Earth-Abundant Semiconductors with Plasmon-Enhanced Light Absorption  

SciTech Connect (OSTI)

Progress is reported in these areas: Plasmonic Light Trapping in Thin Film a-Si Solar Cells; Plasmonic Light Trapping in Thin InGaN Quantum Well Solar Cells; and Earth Abundant Cu{sub 2}O and Zn{sub 3}P{sub 2} Solar Cells.

Atwater, Harry

2012-04-30T23:59:59.000Z

190

Printed assemblies of ultrathin, microscale inorganic light emitting diodes for deformable and semitransparent displays  

DOE Patents [OSTI]

Described herein are printable structures and methods for making, assembling and arranging electronic devices. A number of the methods described herein are useful for assembling electronic devices where one or more device components are embedded in a polymer which is patterned during the embedding process with trenches for electrical interconnects between device components. Some methods described herein are useful for assembling electronic devices by printing methods, such as by dry transfer contact printing methods. Also described herein are GaN light emitting diodes and methods for making and arranging GaN light emitting diodes, for example for display or lighting systems.

Rogers, John A; Nuzzo, Ralph; Kim, Hoon-sik; Brueckner, Eric; Park, Sang Il; Kim, Rak Hwan

2014-10-21T23:59:59.000Z

191

A micrometer-size movable light emitting area in a resonant tunneling light emitting diode  

SciTech Connect (OSTI)

We report on the fabrication of a micrometer-size movable light emitting area in a GaAs/AlAs quantum well resonant tunneling p-i-n diode. The spatial position of the micrometer-size light emitting area shifts linearly with increasing applied bias, up to 30??m for a bias increment of 0.2?V. Also, the simultaneous resonant tunneling injection of both electrons and holes into the quantum well states is achieved at specific positions of the diode, thus resulting in a tenfold increase of the electroluminescence intensity.

Pettinari, G., E-mail: giorgio.pettinari@cnr.it [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); National Research Council (CNR), Institute for Photonics and Nanotechnologies (IFN-CNR), Via Cineto Romano 42, 00156 Roma (Italy); Balakrishnan, N.; Makarovsky, O.; Campion, R. P.; Patanè, A. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)] [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Polimeni, A.; Capizzi, M. [CNISM-Dipartimento di Fisica, Sapienza Università di Roma, P.le A. Moro 2, 00185 Roma (Italy)] [CNISM-Dipartimento di Fisica, Sapienza Università di Roma, P.le A. Moro 2, 00185 Roma (Italy)

2013-12-09T23:59:59.000Z

192

GaInP/GaAs/GaInAs Monolithic Tandem Cells for High-Performance Solar Concentrators  

SciTech Connect (OSTI)

We present a new approach for ultra-high-performance tandem solar cells that involves inverted epitaxial growth and ultra-thin device processing. The additional degree of freedom afforded by the inverted design allows the monolithic integration of high-, and medium-bandgap, lattice-matched (LM) subcell materials with lower-bandgap, lattice-mismatched (LMM) materials in a tandem structure through the use of transparent compositionally graded layers. The current work concerns an inverted, series-connected, triple-bandgap, GaInP (LM, 1.87 eV)/GaAs (LM, 1.42 eV)/GaInAs (LMM, {approx}1 eV) device structure grown on a GaAs substrate. Ultra-thin tandem devices are fabricated by mounting the epiwafers to pre-metallized Si wafer handles and selectively removing the parent GaAs substrate. The resulting handle-mounted, ultra-thin tandem cells have a number of important advantages, including improved performance and potential reclamation/reuse of the parent substrate for epitaxial growth. Additionally, realistic performance modeling calculations suggest that terrestrial concentrator efficiencies in the range of 40-45% are possible with this new tandem cell approach. A laboratory-scale (0.24 cm2), prototype GaInP/GaAs/GaInAs tandem cell with a terrestrial concentrator efficiency of 37.9% at a low concentration ratio (10.1 suns) is described, which surpasses the previous world efficiency record of 37.3%.

Wanlass, M. W.; Ahrenkiel, S. P.; Albin, D. S.; Carapella, J. J.; Duda, A.; Emery, K.; Geisz, J. F.; Jones, K.; Kurtz, S.; Moriarty, T.; Romero, M. J.

2005-08-01T23:59:59.000Z

193

FUPWG Meeting Agenda - Atlanta, GA | Department of Energy  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

Atlanta, GA FUPWG Meeting Agenda - Atlanta, GA Energy on My Mind FUPWG Atlanta, GA May 3-4, 2006 Hosted by: AGL Resources Logo May 3-4, 2006 Hosted by AGL Resources Atlanta,...

194

TEM Characterization of InAs/GaAs Quantum Dots Capped by a GaSb/GaAs Layer  

SciTech Connect (OSTI)

It is well known that there is intense interest in expanding the usable wavelength for electronic devices. This is one of the reasons to study new self-assembled semiconductor nanostructures. Telecommunication applications use InGaAsP/InP emitting at 1.3 and 1.55 m. Research efforts are dedicated to develop GaAs technology in order to achieve emission at the same range as InP, so GaAs could be used for optical fibre communications. Ga(As)Sb on InAs/GaAs quantum dots (QDs) is a promising nanostructure to be used in telecommunications. The introduction of antimony during or after the QDs growth is an effective solution to obtain a red shift in the emission wavelength, even at room temperature.

Beltran, AM [Universidad de Cadiz, Spain; Ben, Teresa [Universidad de Cadiz, Spain; Sanchez, AM [Universidad de Cadiz, Spain; Sales Lerida, David [ORNL; Chisholm, Matthew F [ORNL; Varela del Arco, Maria [ORNL; Pennycook, Stephen J [ORNL; Galindo, Pedro [Universidad de Cadiz, Spain; Ripalda, JM [Instituto de Microelectronica de Madrid (CNM, CSIC); Molina Rubio, Sergio I [ORNL

2008-01-01T23:59:59.000Z

195

Nanostructural engineering of nitride nucleation layers for GaN substrate dislocation reduction.  

SciTech Connect (OSTI)

With no lattice matched substrate available, sapphire continues as the substrate of choice for GaN growth, because of its reasonable cost and the extensive prior experience using it as a substrate for GaN. Surprisingly, the high dislocation density does not appear to limit UV and blue LED light intensity. However, dislocations may limit green LED light intensity and LED lifetime, especially as LEDs are pushed to higher current density for high end solid state lighting sources. To improve the performance for these higher current density LEDs, simple growth-enabled reductions in dislocation density would be highly prized. GaN nucleation layers (NLs) are not commonly thought of as an application of nano-structural engineering; yet, these layers evolve during the growth process to produce self-assembled, nanometer-scale structures. Continued growth on these nuclei ultimately leads to a fully coalesced film, and we show in this research program that their initial density is correlated to the GaN dislocation density. In this 18 month program, we developed MOCVD growth methods to reduce GaN dislocation densities on sapphire from 5 x 10{sup 8} cm{sup -2} using our standard delay recovery growth technique to 1 x 10{sup 8} cm{sup -2} using an ultra-low nucleation density technique. For this research, we firmly established a correlation between the GaN nucleation thickness, the resulting nucleation density after annealing, and dislocation density of full GaN films grown on these nucleation layers. We developed methods to reduce the nuclei density while still maintaining the ability to fully coalesce the GaN films. Ways were sought to improve the GaN nuclei orientation by improving the sapphire surface smoothness by annealing prior to the NL growth. Methods to eliminate the formation of additional nuclei once the majority of GaN nuclei were developed using a silicon nitride treatment prior to the deposition of the nucleation layer. Nucleation layer thickness was determined using optical reflectance and the nucleation density was determined using atomic force microscopy (AFM) and Nomarski microscopy. Dislocation density was measured using X-ray diffraction and AFM after coating the surface with silicon nitride to delineate all dislocation types. The program milestone of producing GaN films with dislocation densities of 1 x 10{sup 8} cm{sup -2} was met by silicon nitride treatment of annealed sapphire followed by the multiple deposition of a low density of GaN nuclei followed by high temperature GaN growth. Details of this growth process and the underlying science are presented in this final report along with problems encountered in this research and recommendations for future work.

Koleske, Daniel David; Lee, Stephen Roger; Lemp, Thomas Kerr; Coltrin, Michael Elliott; Cross, Karen Charlene; Thaler, Gerald

2009-07-01T23:59:59.000Z

196

Mg doping of GaN grown by plasma-assisted molecular beam epitaxy under nitrogen-rich conditions  

SciTech Connect (OSTI)

Acceptor doping of GaN with Mg during plasma-assisted molecular beam epitaxy, under N-rich conditions and a relatively high growth temperature of 740 deg. C, was investigated. The p-doping level steadily increases with increasing Mg flux. The highest doping level achieved, determined from Hall measurements, is 2.1x10{sup 18} cm{sup -3}. The corresponding doping efficiency and hole mobility are approx4.9% and 3.7 cm{sup 2}/V s at room temperature. Cross-sectional transmission electron microscopy and photoluminescence measurements confirm good crystalline and optical quality of the Mg-doped layers. An InGaN/GaN quantum dot light emitting diode (lambda{sub peak}=529 nm) with p-GaN contact layers grown under N-rich condition exhibits a low series resistance of 9.8 OMEGA.

Zhang Meng; Bhattacharya, Pallab; Guo Wei; Banerjee, Animesh [Department of Electrical Engineering and Computer Science, Solid-State Electronics Laboratory, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States)

2010-03-29T23:59:59.000Z

197

Sustainable Office Lighting Options  

E-Print Network [OSTI]

Sustainable Office Lighting Options Task Lighting: Task lighting is a localized method of lighting a workspace so that additional, unnecessary lighting is eliminated, decreasing energy usage and costs. Illumination levels in the targeted work areas are higher with task lighting than with the ambient levels

Massachusetts at Amherst, University of

198

Violet to deep-ultraviolet InGaN/GaN and GaN/AlGaN quantum structures for UV electroabsorption modulators  

E-Print Network [OSTI]

focused on the demonstration of ultraviolet UV optoelectronic devices. Such devices hold promise, material related problems complicate the growth of such optoelectronic devices oper- ating at short wavelengths. With the use of InGaN/GaN quantum structures, optoelectronic devices operating in vis- ible

Demir, Hilmi Volkan

199

High-Efficiency Nitride-Based Photonic Crystal Light Sources  

Broader source: Energy.gov [DOE]

The University of California Santa Barbara (UCSB) is maximizing the efficiency of a white LED by enhancing the external quantum efficiency using photonic crystals to extract light that would normally be confined in a conventional structure. Ultimate efficiency can only be achieved by looking at the internal structure of light. To do this, UCSB is focusing on maximizing the light extraction efficiency and total light output from light engines driven by Gallium Nitride (GaN)-based LEDs. The challenge is to engineer large overlap (interaction) between modes and photonic crystals. The project is focused on achieving high extraction efficiency in LEDs, controlled directionality of emitted light, integrated design of vertical device structure, and nanoscale patterning of lateral structure.

200

GaN-Ready Aluminum Nitride Substrates for Cost-Effective, Very Low Dislocation Density III-Nitride LED's  

SciTech Connect (OSTI)

The objective of this project was to develop and then demonstrate the efficacy of a costeffective approach for a low defect density substrate on which AlInGaN LEDs can be fabricated. The efficacy of this “GaN-ready” substrate would then be tested by growing high efficiency, long lifetime InxGa1-xN blue LEDs. The approach used to meet the project objectives was to start with low dislocation density AlN single-crystal substrates and grow graded AlxGa1-xN layers on top. Pseudomorphic AlxGa1-xN epitaxial layers grown on bulk AlN substrates were used to fabricate light emitting diodes and demonstrate better device performance as a result of the low defect density in these layers when benched marked against state-of-the-art LEDs fabricated on sapphire substrates. The pseudomorphic LEDs showed excellent output powers compared to similar wavelength devices grown on sapphire substrates, with lifetimes exceeding 10,000 hours (which was the longest time that could reliably be estimated). In addition, high internal quantum efficiencies were demonstrated at high driving current densities even though the external quantum efficiencies were low due to poor photon extraction. Unfortunately, these pseudomorphic LEDs require high Al content so they emit in the ultraviolet. Sapphire based LEDs typically have threading dislocation densities (TDD) > 108 cm-2 while the pseudomorphic LEDs have TDD ? 105 cm-2. The resulting TDD, when grading the AlxGa1-xN layer all the way to pure GaN to produce a “GaN-ready” substrate, has varied between the mid 108 down to the 106 cm-2. These inconsistencies are not well understood. Finally, an approach to improve the LED structures on AlN substrates for light extraction efficiency was developed by thinning and roughening the substrate.

Sandra Schujman; Leo Schowalter

2010-10-15T23:59:59.000Z

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201

COMM-OPINION-ORDER, 76 FERC 61,347, Promoting Wholesale Competition Through Open-Access Non-discriminatory Transmission Services by Public Utilities, Docket No. RM95-8-000, Recovery of Stranded Costs by  

E-Print Network [OSTI]

COMM-OPINION-ORDER, 76 FERC ¶61,347, Promoting Wholesale Competition Through Open-Access Non Incorporated Promoting Wholesale Competition Through Open-Access Non-discriminatory Transmission Services Utilities, Docket No. RM94-7-001 [62,646] [¶61,347] Promoting Wholesale Competition Through Open-Access Non

Laughlin, Robert B.

202

COMM-OPINION-ORDER, 75 FERC 61,208, Promoting Wholesale Competition Through Open Access Non-discriminatory Transmission Services by Public Utilities; Recovery of Stranded Costs by Public Utilities and  

E-Print Network [OSTI]

COMM-OPINION-ORDER, 75 FERC ¶61,208, Promoting Wholesale Competition Through Open Access Non Wholesale Competition Through Open Access Non-discriminatory Transmission Services by Public Utilities-7-001 [61,687] [¶61,208] Promoting Wholesale Competition Through Open Access Non-discriminatory Transmission

Laughlin, Robert B.

203

Structural and optical properties of InGaN–GaN nanowire heterostructures grown by molecular beam epitaxy  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

InGaN/GaN nanowire (NW) heterostructures grown by plasma assisted molecular beam epitaxy were studied in comparison to their GaN and InGaN counterparts. The InGaN/GaN heterostructure NWs are composed of a GaN NW, a thin InGaN shell, and a multifaceted InGaN cap wrapping the top part of the GaN NW. High-resolution transmission electron microscopy (HRTEM) images taken from different parts of a InGaN/GaN NW show a wurtzite structure of the GaN core and the epitaxial InGaN shell around it, while additional crystallographic domains are observed whithin the InGaN cap region. Large changes in the lattice parameter along the wire, from pure GaN to higher In concentration demonstrate the successful growth of a complex InGaN/GaN NW heterostructure. Photoluminescence (PL) spectra of these heterostructure NW ensembles show rather broad and intense emission peak at 2.1 eV. However, ?-PL spectra measured on single NWs reveal a reduced broadening of the visible luminescence. The analysis of the longitudinal optical phonon Raman peak position and its shape reveal a variation in the In content between 20% and 30%, in agreement with the values estimated by PL and HRTEM investigations. The reported studies are important for understanding of the growth and properties of NW heterostructures suitable for applications in optoelectronics and photovoltaics.

Limbach, F. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Gotschke, T. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Stoica, T. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Calarco, R. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Sutter, E. [Brookhaven National Lab., Upton, NY (United States); Ciston, J. [Brookhaven National Lab., Upton, NY (United States); Cusco, R. [Consell Superior d'Investigacions Cientifiques (CSIC), Barcelona (Spain); Artus, L. [Consell Superior d'Investigacions Cientifiques (CSIC), Barcelona (Spain); Kremling, S. [Univ. Wurzburg, Wilhelm Conrad Rontgen Research Centre Complex Matter Systems, Wurzburg (Germany); Hofling, S. [Univ. Wurzburg, Wilhelm Conrad Rontgen Research Centre Complex Matter Systems, Wurzburg (Germany); Worschech, L. [Univ. Wurzburg, Wilhelm Conrad Rontgen Research Centre Complex Matter Systems, Wurzburg (Germany); Grutzmacher, D. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany)

2011-01-07T23:59:59.000Z

204

Ultra-thin ohmic contacts for p-type nitride light emitting devices  

DOE Patents [OSTI]

A flip-chip semiconductor based Light Emitting Device (LED) can include an n-type semiconductor substrate and an n-type GaN epi-layer on the substrate. A p-type GaN epi-layer can be on the n-type GaN epi-layer and a metal ohmic contact p-electrode can be on the p-type GaN epi-layer, where the metal ohmic contact p-electrode can have an average thickness less than about 25 .ANG.. A reflector can be on the metal ohmic contact p-electrode and a metal stack can be on the reflector. An n-electrode can be on the substrate opposite the n-type GaN epi-layer and a bonding pad can be on the n-electrode.

Raffetto, Mark; Bharathan, Jayesh; Haberern, Kevin; Bergmann, Michael; Emerson, David; Ibbetson, James; Li, Ting

2014-06-24T23:59:59.000Z

205

PUBLISHED ONLINE: 17 OCTOBER 2010 | DOI: 10.1038/NMAT2879 Waterproof AlInGaP optoelectronics on  

E-Print Network [OSTI]

InGaP optoelectronics on stretchable substrates with applications in biomedicine and robotics Rak-Hwan Kim1 , Dae opportunities for optoelectronic devices. A ll established forms of inorganic light-emitting diodes (LEDs restricting the ways in which these devices can be used. Research in organic optoelectronic materials

Rogers, John A.

206

Spectral hole burnings at high energy tails in spontaneous emission and hot carrier relaxation in InGaAsP lasers  

SciTech Connect (OSTI)

Spectral hole burnings in spontaneous emission spectra from 1.3 ..mu..m InGaAsP lasers were found. The results are understood on the basis of population burnings of holes associated with the saturation of intervalence-band absorption. Theoretical results on hot carrier relaxation are shown to explain the population burnings, pointing out an importance of nonequilibrium optical phonon populations in the active layers of long wavelength InGaAsP lasers and light emitting diodes (LED's).

Yamanishi, M.; Mikoshiba, N.; Nonomura, K.; Suemune, I.

1983-06-01T23:59:59.000Z

207

Lighting Options for Homes.  

SciTech Connect (OSTI)

This report covers many aspects of various lighting options for homes. Types of light sources described include natural light, artificial light, incandescent lamps, fluorescent lamps, and high intensity discharge lamps. A light source selection guide gives the physical characteristics of these, design considerations, and common applications. Color, strategies for efficient lighting, and types of lighting are discussed. There is one section giving tips for various situations in specific rooms. Rooms and types of fixtures are shown on a matrix with watts saved by using the recommended type lighting for that room and room location. A major emphasis of this report is saving energy by utilizing the most suitable, recommended lighting option. (BN)

Baker, W.S.

1991-04-01T23:59:59.000Z

208

Ohmic contacts to n-GaSb  

E-Print Network [OSTI]

in the semiconductor is measured during the deposition of the metal contact. In using method 1, the I-V characteristics is plotted. The thermionic emission theory predicts the current-voltage characteristics of Schottky diodes as [13]: J(rhcrmionic) = A" T' exp... of different work functions. This situation is also true for metal contacts to n-GaSb. Polyakov et al. [14] examined the Schottky diodes of Al, Au, In, Pd, Ga, and Sb on Te doped n-GaSb. They used the C-V measurements methods. They reported that barrier...

Yang, Zhengchong

2012-06-07T23:59:59.000Z

209

Dependence of the ground-state transition energy versus optical pumping in GaAsSb/InGaAs/GaAs heterostructures  

SciTech Connect (OSTI)

In this work, we report on the time-resolved photoluminescence studies of a double quantum well In{sub 0.2}Ga{sub 0.8}As/GaAs{sub 0.8}Sb{sub 0.2}/GaAs heterostructure which, in contrast to the GaAsSb/GaAs structures, is expected to provide effective confinement of electrons due to additional InGaAs layer. The studies at 4.2?K have revealed a complicated nonmonotonic dependence of the ground-state transition energy on the concentration of nonequilibrium charge carriers in the quantum well. The effect observed in this work is important in terms of creating sources of radiation, including stimulated emission, on the basis of InGaAs/GaAsSb/GaAs structures.

Morozov, S. V.; Kryzhkov, D. I., E-mail: krizh@ipmras.ru; Aleshkin, V. Ya. [Institute for Physics of Microstructures, RAS, 603950 Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation); Yablonsky, A. N.; Krasilnik, Z. F. [Institute for Physics of Microstructures, RAS, 603950 Nizhny Novgorod (Russian Federation); Zvonkov, B. N.; Vikhrova, O. V. [Physical-Technical Research Institute, Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation)

2014-01-13T23:59:59.000Z

210

Highly uniform, multi-stacked InGaAs/GaAs quantum dots embedded in a GaAs nanowire  

SciTech Connect (OSTI)

We demonstrate a highly uniform, dense stack of In{sub 0.22}Ga{sub 0.78}As/GaAs quantum dot (QD) structures in a single GaAs nanowire (NW). The size (and hence emission energy) of individual QD is tuned by careful control of the growth conditions based on a diffusion model of morphological evolution of NWs and optical characterization. By carefully tailoring the emission energies of individual QD, dot-to-dot inhomogeneous broadening of QD stacks in a single NW can be as narrow as 9.3?meV. This method provides huge advantages over traditional QD stack using a strain-induced Stranski-Krastanow growth scheme. We show that it is possible to fabricate up to 200 uniform QDs in single GaAs NWs using this growth technique without degradation of the photoluminescence intensity.

Tatebayashi, J., E-mail: tatebaya@iis.u-tokyo.ac.jp; Ota, Y. [NanoQUINE, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Ishida, S.; Nishioka, M.; Iwamoto, S.; Arakawa, Y. [NanoQUINE, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

2014-09-08T23:59:59.000Z

211

Mobile lighting apparatus  

DOE Patents [OSTI]

A mobile lighting apparatus includes a portable frame such as a moveable trailer or skid having a light tower thereon. The light tower is moveable from a stowed position to a deployed position. A hydrogen-powered fuel cell is located on the portable frame to provide electrical power to an array of the energy efficient lights located on the light tower.

Roe, George Michael; Klebanoff, Leonard Elliott; Rea, Gerald W; Drake, Robert A; Johnson, Terry A; Wingert, Steven John; Damberger, Thomas A; Skradski, Thomas J; Radley, Christopher James; Oros, James M; Schuttinger, Paul G; Grupp, David J; Prey, Stephen Carl

2013-05-14T23:59:59.000Z

212

Synthesis, morphology and optical properties of GaN and AlGaN semiconductor nanostructures  

SciTech Connect (OSTI)

Hexagonal Gallium Nitride (GaN) and Aluminum Gallium Nitride (AlGaN) nanoparticles were synthesized by sol-gel method using Ethylene Diamine Tetra Acetic acid (EDTA) complex route. Powder X-ray diffraction (PXRD) analysis confirms the hexagonal wurtzite structure of GaN and Al{sub 0.25}Ga{sub 0.75}N nanoparticles. Surface morphology and elemental analysis were carried out by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscopy (EDX). The room temperature Photoluminescence (PL) study shows the near band edge emission for GaN at 3.35 eV and at 3.59 eV for AlGaN nanoparticles. The Aluminum (Al) composition of 20% has been obtained from PL emission around 345 nm.

Kuppulingam, B., E-mail: drbaskar2009@gmail.com; Singh, Shubra, E-mail: drbaskar2009@gmail.com; Baskar, K., E-mail: drbaskar2009@gmail.com [Crystal Growth Centre, Anna University, Chennai-600025 (India)

2014-04-24T23:59:59.000Z

213

Multi-bands photoconductive response in AlGaN/GaN multiple quantum wells  

SciTech Connect (OSTI)

Based on the optical transitions among the quantum-confined electronic states in the conduction band, we have fabricated multi-bands AlGaN/GaN quantum well infrared photodetectors. Crack-free AlGaN/GaN multiple quantum wells (MQWs) with atomically sharp interfaces have been achieved by inserting an AlN interlayer, which releases most of the tensile strain in the MQWs grown on the GaN underlayer. With significant reduction of dark current by using thick AlGaN barriers, photoconductive responses are demonstrated due to intersubband transition in multiple regions with center wavelengths of 1.3, 2.3, and 4??m, which shows potential applications on near infrared detection.

Chen, G.; Rong, X.; Xu, F. J.; Tang, N. [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Wang, X. Q., E-mail: wangshi@pku.edu.cn; Shen, B., E-mail: bshen@pku.edu.cn [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Fu, K.; Zhang, B. S. [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Ruoshui Road 398, 215123 Suzhou (China); Hashimoto, H.; Yoshikawa, A. [Center for SMART Green Innovation Research, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Ge, W. K. [Department of Physics, Tsinghua University, Beijing 100871 (China)

2014-04-28T23:59:59.000Z

214

Simplified 2DEG carrier concentration model for composite barrier AlGaN/GaN HEMT  

SciTech Connect (OSTI)

The self consistent solution of Schrodinger and Poisson equations is used along with the total charge depletion model and applied with a novel approach of composite AlGaN barrier based HEMT heterostructure. The solution leaded to a completely new analytical model for Fermi energy level vs. 2DEG carrier concentration. This was eventually used to demonstrate a new analytical model for the temperature dependent 2DEG carrier concentration in AlGaN/GaN HEMT.

Das, Palash, E-mail: d.palash@gmail.com; Biswas, Dhrubes, E-mail: d.palash@gmail.com [Indian Institute of Technology Kharagpur, Kharagpur - 721302, West Bengal (India)

2014-04-24T23:59:59.000Z

215

EK101 Engineering Light Smart Lighting  

E-Print Network [OSTI]

EK101 Engineering Light Smart Lighting Homework for 9/10 1. Make an estimate (using if the patent is granted.) 3. What is a lumen? A lux? How are the two related? How would you use a lux meter, (Lux, Lumens/m2) Luminous Flux: Perceivable light power from a source, (Lumens) Use the lux meter

Bifano, Thomas

216

Specific light in sculpture  

E-Print Network [OSTI]

Specific light is defined as light from artificial or altered natural sources. The use and manipulation of light in three dimensional sculptural work is discussed in an historic and contemporary context. The author's work ...

Powell, John William

1989-01-01T23:59:59.000Z

217

Electron Transport in a Two-Dimensional Electron Gas at GaAs/AlGaAs Heterointerface  

E-Print Network [OSTI]

in condensed matters. Two-dimensional electron gas (2DEG) at the GaAs/AlGaAs hetero-interface o ersThesis Electron Transport in a Two-Dimensional Electron Gas at GaAs/AlGaAs Heterointerface under of the art samples, the mean free path of electrons exceeds 10;4 m at low temperature. The achievement

Katsumoto, Shingo

218

InAsGaPInGaP high-temperature power Schottky rectifier and J. M. Woodall  

E-Print Network [OSTI]

°C. Further improvement of the thermal stability is expected to be achieved by reducing the diffusion is thought to be due to strong covalent bonding at the InAs/GaP interface. The InAs/GaP heterointerface effectively blocks impurity diffusion. Since InGaP is superior to GaP for high-power applica- tions, as shown

Woodall, Jerry M.

219

GaTe semiconductor for radiation detection  

DOE Patents [OSTI]

GaTe semiconductor is used as a room-temperature radiation detector. GaTe has useful properties for radiation detectors: ideal bandgap, favorable mobilities, low melting point (no evaporation), non-hygroscopic nature, and availability of high-purity starting materials. The detector can be used, e.g., for detection of illicit nuclear weapons and radiological dispersed devices at ports of entry, in cities, and off shore and for determination of medical isotopes present in a patient.

Payne, Stephen A. (Castro Valley, CA); Burger, Arnold (Nashville, TN); Mandal, Krishna C. (Ashland, MA)

2009-06-23T23:59:59.000Z

220

Room-temperature mid-infrared “M”-type GaAsSb/InGaAs quantum well lasers on InP substrate  

SciTech Connect (OSTI)

We have demonstrated experimentally the InP-based “M”-type GaAsSb/InGaAs quantum-well (QW) laser lasing at 2.41??m at room temperature by optical pumping. The threshold power density per QW and extracted internal loss were about 234?W/cm{sup 2} and 20.5?cm{sup ?1}, respectively. The temperature-dependent photoluminescence (PL) and lasing spectra revealed interesting characteristics for this type of lasers. Two distinct regions in the temperature dependent threshold behavior were observed and the transition temperature was found to coincide with the cross over point of the PL and lasing emission peaks. The current-voltage characteristic of “M”-type QW laser was superior to the inverse “W”-type one due to its thinner barrier for holes. Further improvement of the “M”-type QW structure could lead to a cost-effective mid-infrared light source.

Chang, Chia-Hao; Li, Zong-Lin; Pan, Chien-Hung; Lu, Hong-Ting; Lee, Chien-Ping; Lin, Sheng-Di, E-mail: sdlin@mail.nctu.edu.tw [Department of Electronics Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan (China)

2014-02-14T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Electroluminescence of InGaAs/GaAs quantum-size heterostructures with (III, Mn)V and Ni ferromagnetic injectors  

SciTech Connect (OSTI)

Electroluminescence characteristics of light-emitting diodes based on InGaAs/GaAs quantum well heterostructures with an injector layer made of ferromagnetic metal (Ni), semimetal compound (MnSb), or magnetic semiconductor (InMnAs) were comparatively studied. The general feature is electroluminescence quenching as the spacer layer thickness between a quantum well and a magnetic injector decreases. It was found that the temperature dependence of the electroluminescence in diodes with Ni and MnSb is caused by thermal ejection of carriers from the quantum well; in diodes with InMnAs, it is caused by the temperature dependence of the carrier concentration in magnetic semiconductor and thermal ejection of carriers from the quantum well in the high-temperature region.

Prokof'eva, M. M., E-mail: marinaprkfeva@rambler.ru [Lobachevsky State University (Russian Federation); Dorokhin, M. V.; Danilov, Yu. A.; Kudrin, A. V.; Vikhrova, O. V. [Lobachevsky State University of Nizhni Novgorod, Physicotechnical Research Institute (Russian Federation)

2010-11-15T23:59:59.000Z

222

Light sources based on semiconductor current filaments  

DOE Patents [OSTI]

The present invention provides a new type of semiconductor light source that can produce a high peak power output and is not injection, e-beam, or optically pumped. The present invention is capable of producing high quality coherent or incoherent optical emission. The present invention is based on current filaments, unlike conventional semiconductor lasers that are based on p-n junctions. The present invention provides a light source formed by an electron-hole plasma inside a current filament. The electron-hole plasma can be several hundred microns in diameter and several centimeters long. A current filament can be initiated optically or with an e-beam, but can be pumped electrically across a large insulating region. A current filament can be produced in high gain photoconductive semiconductor switches. The light source provided by the present invention has a potentially large volume and therefore a potentially large energy per pulse or peak power available from a single (coherent) semiconductor laser. Like other semiconductor lasers, these light sources will emit radiation at the wavelength near the bandgap energy (for GaAs 875 nm or near infra red). Immediate potential applications of the present invention include high energy, short pulse, compact, low cost lasers and other incoherent light sources.

Zutavern, Fred J. (Albuquerque, NM); Loubriel, Guillermo M. (Albuquerque, NM); Buttram, Malcolm T. (Sandia Park, NM); Mar, Alan (Albuquerque, NM); Helgeson, Wesley D. (Albuquerque, NM); O'Malley, Martin W. (Edgewood, NM); Hjalmarson, Harold P. (Albuquerque, NM); Baca, Albert G. (Albuquerque, NM); Chow, Weng W. (Cedar Crest, NM); Vawter, G. Allen (Albuquerque, NM)

2003-01-01T23:59:59.000Z

223

Near-surface depletion of antimony during the growth of GaAsSb and GaAs/GaAsSb nanowires  

SciTech Connect (OSTI)

The near-surface reduction of the Sb mole fraction during the growth of GaAsSb nanowires (NWs) and GaAs NWs with GaAsSb inserts has been studied using quantitative high-angle annular dark field scanning transmission electron microscopy (STEM). A model for diffusion of Sb in the hexagonal NWs was developed and employed in combination with the quantitative STEM analysis. GaAsSb NWs grown by Ga-assisted molecular beam epitaxy (MBE) and GaAs/GaAsSb NWs grown by Ga- and Au-assisted MBE were investigated. At the high temperatures employed in the NW growth, As-Sb exchange at and outward diffusion of Sb towards the surface take place, resulting in reduction of the Sb concentration at and near the surface in the GaAsSb NWs and the GaAsSb inserts. In GaAsSb NWs, an increasing near-surface depletion of Sb was observed towards the bottom of the NW due to longer exposure to the As beam flux. In GaAsSb inserts, an increasing change in the Sb concentration profile was observed with increasing post-insert axial GaAs growth time, resulting from a combined effect of radial GaAs overgrowth and diffusion of Sb. The effect of growth temperature on the diffusion of Sb in the GaAsSb inserts was identified. The consequences of these findings for growth optimization and the optoelectronic properties of GaAsSb are discussed.

Kauko, H.; Helvoort, A. T. J. van, E-mail: a.helvoort@ntnu.no [Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim (Norway); Fimland, B. O.; Munshi, A. M. [Department of Electronics and Telecommunications, NTNU, Trondheim (Norway); Grieb, T.; Müller, K.; Rosenauer, A. [Institut für Festkörperphysik, Universität Bremen, Bremen (Germany)

2014-10-14T23:59:59.000Z

224

REGULAR PAPER Improvement of Surge Protection by Using an AlGaN/GaN-Based  

E-Print Network [OSTI]

the metal oxide varistor (MOV) and resistor (R) in a state-of-the-art surge protection circuit), metal oxide varistor (MOV), and transient voltage suppressor (TVS) diodes are the state-of-the- artREGULAR PAPER Improvement of Surge Protection by Using an AlGaN/GaN-Based Metal­Semiconductor­Metal

Chow, Lee

225

Lattice-matched epitaxial GaInAsSb/GaSb thermophotovoltaic devices  

SciTech Connect (OSTI)

The materials development of Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} alloys for lattice-matched thermophotovoltaic (TPV) devices is reported. Epilayers with cutoff wavelength 2--2.4 {micro}m at room temperature and lattice-matched to GaSb substrates were grown by both low-pressure organometallic vapor phase epitaxy and molecular beam epitaxy. These layers exhibit high optical and structural quality. For demonstrating lattice-matched thermophotovoltaic devices, p- and n-type doping studies were performed. Several TPV device structures were investigated, with variations in the base/emitter thicknesses and the incorporation of a high bandgap GaSb or AlGaAsSb window layer. Significant improvement in the external quantum efficiency is observed for devices with an AlGaAsSb window layer compared to those without one.

Wang, C.A.; Choi, H.K.; Turner, G.W.; Spears, D.L.; Manfra, M.J. [Massachusetts Inst. of Tech., Lexington, MA (United States). Lincoln Lab.; Charache, G.W. [Lockheed Martin, Inc., Schenectady, NY (United States)

1997-05-01T23:59:59.000Z

226

Gallium surface diffusion on GaAs (001) surfaces measured by crystallization dynamics of Ga droplets  

SciTech Connect (OSTI)

We present accurate measurements of Ga cation surface diffusion on GaAs surfaces. The measurement method relies on atomic force microscopy measurement of the morphology of nano–disks that evolve, under group V supply, from nanoscale group III droplets, earlier deposited on the substrate surface. The dependence of the radius of such nano-droplets on crystallization conditions gives direct access to Ga diffusion length. We found an activation energy for Ga on GaAs(001) diffusion E{sub A}=1.31±0.15 eV, a diffusivity prefactor of D{sub 0}?=?0.53(×2.1±1) cm{sup 2} s{sup ?1} that we compare with the values present in literature. The obtained results permit to better understand the fundamental physics governing the motion of group III ad–atoms on III–V crystal surfaces and the fabrication of designable nanostructures.

Bietti, Sergio, E-mail: sergio.bietti@mater.unimib.it; Somaschini, Claudio; Esposito, Luca; Sanguinetti, Stefano [L–NESS and Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, Via Cozzi 55, I–20125 Milano (Italy); Fedorov, Alexey [L–NESS and CNR–IFN, via Anzani 42, I-22100 Como (Italy)

2014-09-21T23:59:59.000Z

227

Study and development of tunable, single mode AlGaAs/GaAs lasers  

SciTech Connect (OSTI)

Liquid phase epitaxy has been employed in this study to fabricate two-section wavelength tunable lasers. GaAs/AlGaAs and In GaAsP/InP material system have been used for fabricating the lasers. Both direct (butt) coupling and evanescent coupling approaches have been studied. The complications associated with the regrowth process have been responsible for poor laser performance. Some DBR gratings for three-section lasers have been made using the electron beam lithography at UCSD. A simple set up has been tested to measure the wavelength shift of GaAs/AlGaAs lasers. Also, a simple structure which avoids the regrowth process has been proposed for the two-section laser. 9 refs., 14 figs.

Yu, P.K.L.; Liu, J.C. (California Univ., San Diego, La Jolla, CA (USA). Dept. of Electrical and Computer Engineering)

1990-09-01T23:59:59.000Z

228

Le travail comme capacit : de la subordination la libert ?1 Sen met au centre de sa conception du dveloppement, l'institution d'un "libre march de l'emploi", par  

E-Print Network [OSTI]

capacité repose en premier lieu, dans l'analyse d'Amartya Sen, sur la liberté réelle de choix en se1 Le travail comme « capacité » : de la subordination à la liberté ?1 Résumé : Sen met au centre de conception du « libre marché de l'emploi » dans la réflexion de Sen, à partir de sa conception du

Paris-Sud XI, Université de

229

Lighting and Daylight Harvesting  

E-Print Network [OSTI]

exposing us to the latest products and technologies. Daylight Harvesting A system of controlling the direction and the quantity of light both natural and artificial within a given space. This implies: Control of fenestration in terms of size..., transmission and direction. Control of reflected light within a space. Control of electric light in terms of delivery and amount Daylight harvesting systems are typically designed to maintain a minimum recommended light level. This light level...

Bos, J.

2011-01-01T23:59:59.000Z

230

c IEEE, 2013. This is the author's version of the work. It is posted here by permission of IEEE for your personal use. Not for redistribution. The definitive version is accepted for 2013 IEEE Online Conference on Green Communications (OnlineGreenComm 2013  

E-Print Network [OSTI]

and backbone network) [2]. However, the energy consumption in wired access networks is proportional's energy consumption are expected (potentially even overtaking the access network's consumption [3 Conference on Green Communications (OnlineGreenComm 2013). Power Consumption Evaluation of Circuit

Wichmann, Felix

231

Quantum confinement in GaP nanoclusters  

SciTech Connect (OSTI)

We have prepared GaP and GaAs nanoclusters from organometallic condensation reactions of E[Si(ChH{sub 3})3]3 (E = P, As) and GaCl{sub 3}. The size of the as synthesized clusters is 10 {Angstrom} to 15 {Angstrom}. Larger clusters of 20 {Angstrom} to 30 {Angstrom} size were obtained by thermal annealing of the as grown material. X-ray diffraction and transmission electron microscopy confirm the high crystalline quality. A lattice contraction of 6.7% could be seen for 10 {Angstrom} sized GaAs clusters. The clusters are nearly spherical in shape. Optical absorption spectra show a distinct line which can be assigned to the fundamental transition of the quantum confined electronic state. The measured blue shift, with respect to the GaP bulk absorption edge is 0.53 eV. As the cluster is smaller than the exciton radius, we can calculate the cluster size from this blue shift and obtain 20.2 {Angstrom}, consistent with the results from X-ray diffraction of 19.5 {Angstrom} for the same sample.

Laurich, B.K.; Smith, D.C.; Healy, M.D.

1994-06-01T23:59:59.000Z

232

Effect of antimony nano-scale surface-structures on a GaSb/AlAsSb distributed Bragg reflector  

SciTech Connect (OSTI)

Effects of antimony crystallization on the surface of GaSb during low temperature molecular beam epitaxy growth are investigated. The geometry of these structures is studied via transmission electron and atomic force microscopies, which show the surface metal forms triangular-shaped, elongated nano-wires with a structured orientation composed entirely of crystalline antimony. By depositing antimony on a GaSb/AlAsSb distributed Bragg reflector, the field is localized within the antimony layer. Polarization dependent transmission measurements are carried out on these nano-structures deposited on a GaSb/AlAsSb distributed Bragg reflector. It is shown that the antimony-based structures at the surface favor transmission of light polarized perpendicular to the wires.

Husaini, S.; Shima, D.; Ahirwar, P.; Rotter, T. J.; Hains, C. P.; Dang, T.; Bedford, R. G.; Balakrishnan, G. [Air Force Research Laboratory, Sensors Directorate, Wright-Patterson AFB, Dayton, OH 45433 (United States)] [Air Force Research Laboratory, Sensors Directorate, Wright-Patterson AFB, Dayton, OH 45433 (United States)

2013-02-11T23:59:59.000Z

233

Ab initio study on noncompensated CrO codoping of GaN for enhanced solar energy conversion  

SciTech Connect (OSTI)

We describe a novel photocatalyst obtained by codoping GaN with CrO, according to a new "noncompensated" codoping concept based on first-principles calculations. The approach enables controllable narrowing of the GaN band gap with significantly enhanced carrier mobility and photocatalytic activity in the visible light region and thus offers immense potential for application in solar energy conversion, water splitting, and a variety of solar-assisted photocatalysis. Our calculations indicate that the formation energy for the cation doping is greatly reduced by noncompensated codoping with an anion. Although Cr doping alone can split the band gap with the formation of an intermediate band, the mobility is low due to carrier trapping by the localized states. The first-principles calculations also demonstrate that CrO codoping of GaN shifts the Fermi level into the conduction band resulting in high carrier density and mobility.

Pan, Hui [ORNL; Gu, Baohua [ORNL; Eres, Gyula [ORNL; Zhang, Zhenyu [ORNL

2010-03-01T23:59:59.000Z

234

Defect studies in low-temperature-grown GaAs  

SciTech Connect (OSTI)

High content of excess As is incorporated in GaAs grown by low-temperature molecular-beam-epitaxy (LTMBE). The excess As exists primarily as As antisite defects AsGa and a lesser extent of gallium vacancies V{sub Ga}. The neutral AsGa-related defects were measured by infrared absorption at 1{mu}m. Gallium vacancies, V{sub Ga}, was investigated by slow positron annihilation. Dependence of defect contents on doping was studied by Si and Be dopants. No free carriers are generated by n-type or p-type doping up to 10{sup 19} cm{sup {minus}3} Si or Be. Raman data indicate Be occupies Ga substitutional sites but Si atom is not substitutional. Si induces more As{sub Ga} in the layer. As As{sub Ga} increases, photoquenchable As{sub Ga} decreases. Fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing reduces neutral As{sub Ga} content around 500C, similar to irradiation damaged and plastically deformed Ga{sub As}, as opposed to bulk grown GaAs in which As{sub Ga}-related defects are stable up to 1100C. The lower temperature defect removal is due to V{sub Ga} enhanced diffusion of As{sub Ga} to As precipitates. The supersaturated V{sub GA} and also decreases during annealing. Annealing kinetics for As{sub Ga}-related defects gives 2.0 {plus_minus} 0.3 eV and 1.5 {plus_minus} 0.3 eV migration enthalpies for the As{sub Ga} and V{sub Ga}. This represents the difference between Ga and As atoms hopping into the vacancy. The non-photoquenchable As{sub Ga}-related defects anneal with an activation energy of 1.1 {plus_minus} 0.3eV. Be acceptors can be activated by 800C annealing. Temperature difference between defect annealing and Be activation formation of As{sub Ga}-Be{sub Ga} pairs. Si donors can only be partially activated.

Bliss, D.E.

1992-11-01T23:59:59.000Z

235

Defect studies in low-temperature-grown GaAs  

SciTech Connect (OSTI)

High content of excess As is incorporated in GaAs grown by low-temperature molecular-beam-epitaxy (LTMBE). The excess As exists primarily as As antisite defects AsGa and a lesser extent of gallium vacancies V[sub Ga]. The neutral AsGa-related defects were measured by infrared absorption at 1[mu]m. Gallium vacancies, V[sub Ga], was investigated by slow positron annihilation. Dependence of defect contents on doping was studied by Si and Be dopants. No free carriers are generated by n-type or p-type doping up to 10[sup 19] cm[sup [minus]3] Si or Be. Raman data indicate Be occupies Ga substitutional sites but Si atom is not substitutional. Si induces more As[sub Ga] in the layer. As As[sub Ga] increases, photoquenchable As[sub Ga] decreases. Fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing reduces neutral As[sub Ga] content around 500C, similar to irradiation damaged and plastically deformed Ga[sub As], as opposed to bulk grown GaAs in which As[sub Ga]-related defects are stable up to 1100C. The lower temperature defect removal is due to V[sub Ga] enhanced diffusion of As[sub Ga] to As precipitates. The supersaturated V[sub GA] and also decreases during annealing. Annealing kinetics for As[sub Ga]-related defects gives 2.0 [plus minus] 0.3 eV and 1.5 [plus minus] 0.3 eV migration enthalpies for the As[sub Ga] and V[sub Ga]. This represents the difference between Ga and As atoms hopping into the vacancy. The non-photoquenchable As[sub Ga]-related defects anneal with an activation energy of 1.1 [plus minus] 0.3eV. Be acceptors can be activated by 800C annealing. Temperature difference between defect annealing and Be activation formation of As[sub Ga]-Be[sub Ga] pairs. Si donors can only be partially activated.

Bliss, D.E.

1992-11-01T23:59:59.000Z

236

Carrier capture dynamics of single InGaAs/GaAs quantum-dot layers  

SciTech Connect (OSTI)

Using 800 nm, 25-fs pulses from a mode locked Ti:Al{sub 2}O{sub 3} laser, we have measured the ultrafast optical reflectivity of MBE-grown, single-layer In{sub 0.4}Ga{sub 0.6}As/GaAs quantum-dot (QD) samples. The QDs are formed via two-stage Stranski-Krastanov growth: following initial InGaAs deposition at a relatively low temperature, self assembly of the QDs occurs during a subsequent higher temperature anneal. The capture times for free carriers excited in the surrounding GaAs (barrier layer) are as short as 140 fs, indicating capture efficiencies for the InGaAs quantum layer approaching 1. The capture rates are positively correlated with initial InGaAs thickness and annealing temperature. With increasing excited carrier density, the capture rate decreases; this slowing of the dynamics is attributed to Pauli state blocking within the InGaAs quantum layer.

Chauhan, K. N.; Riffe, D. M.; Everett, E. A.; Kim, D. J.; Yang, H. [Physics Department, Utah State University, Logan, Utah 84322-4415 (United States)] [Physics Department, Utah State University, Logan, Utah 84322-4415 (United States); Shen, F. K. [Center for Surface Analysis and Applications, Utah State University, Logan, Utah 84322-4415 (United States)] [Center for Surface Analysis and Applications, Utah State University, Logan, Utah 84322-4415 (United States)

2013-05-28T23:59:59.000Z

237

Strain-induced fundamental optical transition in (In,Ga)As/GaP quantum dots  

SciTech Connect (OSTI)

The nature of the ground optical transition in an (In,Ga)As/GaP quantum dot is thoroughly investigated through a million atoms supercell tight-binding simulation. Precise quantum dot morphology is deduced from previously reported scanning-tunneling-microscopy images. The strain field is calculated with the valence force field method and has a strong influence on the confinement potentials, principally, for the conduction band states. Indeed, the wavefunction of the ground electron state is spatially confined in the GaP matrix, close to the dot apex, in a large tensile strain region, having mainly Xz character. Photoluminescence experiments under hydrostatic pressure strongly support the theoretical conclusions.

Robert, C., E-mail: cedric.robert@insa-rennes.fr, E-mail: cedric.robert@tyndall.ie; Pedesseau, L.; Cornet, C.; Jancu, J.-M.; Even, J.; Durand, O. [Université Européenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 Avenue des Buttes de Coësmes, 35708 Rennes (France)] [Université Européenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 Avenue des Buttes de Coësmes, 35708 Rennes (France); Nestoklon, M. O. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation)] [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Pereira da Silva, K. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain) [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); Departamento de Física, Universidade Federal do Ceará, P.O. Box 6030, Fortaleza–CE, 60455-970 (Brazil); Alonso, M. I. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain)] [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); Goñi, A. R. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain) [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); ICREA, Passeig Lluís Companys 23, 08010 Barcelona (Spain); Turban, P. [Equipe de Physique des Surfaces et Interfaces, Institut de Physique de Rennes UMR UR1-CNRS 6251, Université de Rennes 1, F-35042 Rennes Cedex (France)] [Equipe de Physique des Surfaces et Interfaces, Institut de Physique de Rennes UMR UR1-CNRS 6251, Université de Rennes 1, F-35042 Rennes Cedex (France)

2014-01-06T23:59:59.000Z

238

Nucleation and Growth of GaN on GaAs (001) Substrates  

SciTech Connect (OSTI)

The nucleation of GaN thin films on GaAs is investigated for growth at 620 "C. An rf plasma cell is used to generate chemically active nitrogen from N2. An arsenic flux is used in the first eight monolayer of nitride growth to enhance nucleation of the cubic phase. Subsequent growth does not require an As flux to preserve the cubic phase. The nucleation of smooth interfaces and GaN films with low stacking fault densities is dependent upon relative concentrations of active nitrogen species in the plasma and on the nitrogen to gallium flux ratio.

Drummond, Timothy J.; Hafich, Michael J.; Heller, Edwin J.; Lee, Stephen R.; Liliental-Weber, Zuzanna; Ruvimov, Sergei; Sullivan, John P.

1999-05-03T23:59:59.000Z

239

Optical spectroscopy of quantum confined states in GaAs/AlGaAs quantum well tubes  

SciTech Connect (OSTI)

We have investigated the quantum confinement of electronic states in GaAs/Al{sub x}Ga{sub 1?x}As nanowire heterostructures which contain radial GaAs quantum wells of either 4nm or 8nm. Photoluminescence and photoluminescence excitation spectroscopy are performed on single nanowires. We observed emission and excitation of electron and hole confined states. Numerical calculations of the quantum confined states using the detailed structural information on the quantum well tubes show excellent agreement with these optical results.

Shi, Teng; Fickenscher, Melodie; Smith, Leigh; Jackson, Howard [Department of Physics, University of Cincinnati, Cincinnati, OH 45221 (United States); Yarrison-Rice, Jan [Department of Physics, Miami University, Oxford, OH 45056 (United States); Gao, Qiang; Tan, Hoe; Jagadish, Chennupati [Department of Electronic Materials and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Etheridge, Joanne [Monash Centre for Electron Microscopy, Monash University, Victoria, 3800 (Australia); Wong, Bryan M. [Materials Chemistry Department, Sandia National Laboratories, Livermore, CA 94551 (United States)

2013-12-04T23:59:59.000Z

240

On strongly GA-convex functions and stochastic processes  

SciTech Connect (OSTI)

In this study, we introduce strongly GA-convex functions and stochastic processes. We provide related well-known Kuhn type results and Hermite-Hadamard type inequality for strongly GA-convex functions and stochastic processes.

Bekar, Nurgül Okur [Department of Statistics, Giresun University, Giresun (Turkey); Akdemir, Hande Günay; ??can, ?mdat [Department of Mathematics, Giresun University, Giresun (Turkey)

2014-08-20T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Energy absorption in Ni-Mn-Ga/ polymer composites  

E-Print Network [OSTI]

In recent years Ni-Mn-Ga has attracted considerable attention as a new kind of actuator material. Off-stoichiometric single crystals of Ni2MnGa can regularly exhibit 6% strain in tetragonal martensites and orthorhombic ...

Feuchtwanger, Jorge

2006-01-01T23:59:59.000Z

242

The effects of Si-doped prelayers on the optical properties of InGaN/GaN single quantum well structures  

SciTech Connect (OSTI)

In this paper, we report on the effects of including Si-doped (In)GaN prelayers on the low temperature optical properties of a blue-light emitting InGaN/GaN single quantum well. We observed a large blue shift of the photoluminescence peak emission energy and significant increases in the radiative recombination rate for the quantum well structures that incorporated Si-doped prelayers. Simulations of the variation of the conduction and valence band energies show that a strong modification of the band profile occurs for the quantum wells on Si-doped prelayers due to an increase in strength of the surface polarization field. The enhanced surface polarization field opposes the built-in field across the quantum well and thus reduces this built-in electric field. This reduction of the electric field across the quantum well reduces the Quantum Confined Stark Effect and is responsible for the observed blue shift and the change in the recombination dynamics.

Davies, M. J., E-mail: Matthew.Davies-2@Manchester.ac.uk; Dawson, P. [School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL (United Kingdom); Massabuau, F. C.-P.; Oliver, R. A.; Kappers, M. J.; Humphreys, C. J. [Department of Material Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

2014-09-01T23:59:59.000Z

243

Accurate characterization and improvement of GaAs microstrip attenuation  

E-Print Network [OSTI]

Convergence. III. E. 6 Final Model. III. F Simulation Results for 100 um GaAs. . III. F. 1 On-GaAs Microstrip. III. I', 2 Suspended Microstrip Line . . . . 50 . . . . 51 . . . . 54 . . . . 56 . . . . 56 . . . 56 . . . . 64 64 . . . , 64 III. F. 3... Comparison Between On-GaAs and Suspcndcd Microstrip . . . 68 III. F. 4 Microstrip Inductance III. G EM Parameters in CAD Simulations . . III. H Simulation Results for 150 um GaAs. III. I Conclusions and Recommendations. IV RESEARCH ACCOMPLISHMENTS...

Carroll, James Mason

2012-06-07T23:59:59.000Z

244

Kyler Nelson Light Timer  

E-Print Network [OSTI]

designated by the user, the Arduino board will dim the light to save energy. The user designates the time instance, the light is dimmed using pulse width modulation (PWM) in the Arduino's pin number 11

Kachroo, Pushkin

245

Study of gain and photoresponse characteristics for back-illuminated separate absorption and multiplication GaN avalanche photodiodes  

SciTech Connect (OSTI)

The gain and photoresponse characteristics have been numerically studied for back-illuminated separate absorption and multiplication (SAM) GaN avalanche photodiodes (APDs). The parameters of fundamental models are calibrated by simultaneously comparing the simulated dark and light current characteristics with the experimental results. Effects of environmental temperatures and device dimensions on gain characteristics have been investigated, and a method to achieve the optimum thickness of charge layer is obtained. The dependence of gain characteristics and breakdown voltage on the doping concentration of the charge layer is also studied in detail to get the optimal charge layer. The bias-dependent spectral responsivity and quantum efficiency are then presented to study the photoresponse mechanisms inside SAM GaN APDs. It is found the responsivity peak red-shifts at first due to the Franz-Keldysh effect and then blue-shifts due to the reach-through effect of the absorption layer. Finally, a new SAM GaN/AlGaN heterojunction APD structure is proposed for optimizing SAM GaN APDs.

Wang, Xiaodong; Pan, Ming; Hou, Liwei; Xie, Wei [No. 50 Research Institute of China Electronics Technology Group Corporation, 200331 Shanghai (China); Hu, Weida, E-mail: wdhu@mail.sitp.ac.cn; Xu, Jintong; Li, Xiangyang; Chen, Xiaoshuang, E-mail: xschen@mail.sitp.ac.cn; Lu, Wei [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 200083 Shanghai (China)

2014-01-07T23:59:59.000Z

246

Height stabilization of GaSb/GaAs quantum dots by Al-rich capping  

SciTech Connect (OSTI)

GaSb quantum dots (QDs) in a GaAs matrix are investigated with cross-sectional scanning tunneling microscopy (X-STM) and photoluminescence (PL). We observe that Al-rich capping materials prevent destabilization of the nanostructures during the capping stage of the molecular beam epitaxy (MBE) growth process and thus preserves the QD height. However, the strain induced by the absence of destabilization causes many structural defects to appear around the preserved QDs. These defects originate from misfit dislocations near the GaSb/GaAs interface and extend into the capping layer as stacking faults. The lack of a red shift in the QD PL suggests that the preserved dots do not contribute to the emission spectra. We suggest that a better control over the emission wavelength and an increase of the PL intensity is attainable by growing smaller QDs with an Al-rich overgrowth.

Smakman, E. P., E-mail: e.p.smakman@tue.nl; Koenraad, P. M. [Department of Applied Physics, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven (Netherlands); DeJarld, M.; Martin, A. J.; Millunchick, J. [Department of Material Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Luengo-Kovac, M.; Sih, V. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2014-09-01T23:59:59.000Z

247

AIRPORT LIGHTING Session Highlights  

E-Print Network [OSTI]

AIRPORT LIGHTING Session Highlights In May 2002, the Airport Technical Assistance Program, also known as AirTAP, sponsored three airport-lighting training sessions at different locations in Minnesota information on airport lighting and navigational aid equipment selection, funding, maintenance, and operation

Minnesota, University of

248

Advanced Demand Responsive Lighting  

E-Print Network [OSTI]

Advanced Demand Responsive Lighting Host: Francis Rubinstein Demand Response Research Center demand responsive lighting systems ­ Importance of dimming ­ New wireless controls technologies · Advanced Demand Responsive Lighting (commenced March 2007) #12;Objectives · Provide up-to-date information

249

Analysis of the AlGaN/GaN vertical bulk current on Si, sapphire, and free-standing GaN substrates  

SciTech Connect (OSTI)

The vertical bulk (drain-bulk) current (I{sub db}) properties of analogous AlGaN/GaN hetero-structures molecular beam epitaxially grown on silicon, sapphire, and free-standing GaN (FS-GaN) have been evaluated in this paper. The experimental I{sub db} (25-300 Degree-Sign C) have been well reproduced with physical models based on a combination of Poole-Frenkel (trap assisted) and hopping (resistive) conduction mechanisms. The thermal activation energies (E{sub a}), the (soft or destructive) vertical breakdown voltage (V{sub B}), and the effect of inverting the drain-bulk polarity have also been comparatively investigated. GaN-on-FS-GaN appears to adhere to the resistive mechanism (E{sub a} = 0.35 eV at T = 25-300 Degree-Sign C; V{sub B} = 840 V), GaN-on-sapphire follows the trap assisted mechanism (E{sub a} = 2.5 eV at T > 265 Degree-Sign C; V{sub B} > 1100 V), and the GaN-on-Si is well reproduced with a combination of the two mechanisms (E{sub a} = 0.35 eV at T > 150 Degree-Sign C; V{sub B} = 420 V). Finally, the relationship between the vertical bulk current and the lateral AlGaN/GaN transistor leakage current is explored.

Perez-Tomas, A.; Fontsere, A.; Llobet, J. [IMB-CNM-CSIC, Campus UAB, 08193 Bellaterra, Barcelona, CAT (Spain); Placidi, M. [IREC, Jardins Dones de Negre 1, 08930 Sant Adria de Besos, Barcelona (Spain); Rennesson, S.; Chenot, S.; Moreno, J. C.; Cordier, Y. [CRHEA-CNRS, Rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France); Baron, N. [CRHEA-CNRS, Rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France); PICOGIGA International, Pl M. Rebuffat, Courtaboeuf 7, 91140 Villejust (France)

2013-05-07T23:59:59.000Z

250

Multiband GaNAsP Quaternary Alloys  

SciTech Connect (OSTI)

We have synthesized GaN{sub x}As{sub 1-y}P{sub y} alloys (x {approx} 0.3-1% and y = 0-0.4) using nitrogen N ion implantation into GaAsP epilayers followed by pulsed laser melting and rapid thermal annealing techniques. As predicted by the band anticrossing model, the incorporation of N splits the conduction band (E{sub M}) of the GaAs{sub 1-y}P{sub y} substrate, and strong optical transitions from the valence band to the lower (E{sub -}) and upper (E{sub +}) conduction subbands are observed. The relative strengths of the E{sub -} and E{sub +} transition change as the localized N level E{sub N} emerges from the conduction band forming narrow intermediate band for y > 0.3. The results show that GaN{sub x}As{sub 1-x-y}P{sub y} alloys with y > 0.3 is a three band semiconductor alloy with potential applications for high-efficiency intermediate band solar cells.

Yu, K.M.; Walukiewicz, W.; Ager III, J.W.; Bour, D.; Farshchi,R.; Dubon, O.D.; Li, S.X.; Sharp, I.D.; Haller, E.E.

2005-12-08T23:59:59.000Z

251

Light emitting device comprising phosphorescent materials for white light generation  

DOE Patents [OSTI]

The present invention relates to phosphors for energy downconversion of high energy light to generate a broadband light spectrum, which emit light of different emission wavelengths.

Thompson, Mark E.; Dapkus, P. Daniel

2014-07-22T23:59:59.000Z

252

Light Duty Combustion Research: Advanced Light-Duty Combustion...  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

Combustion Research: Advanced Light-Duty Combustion Experiments Light Duty Combustion Research: Advanced Light-Duty Combustion Experiments 2009 DOE Hydrogen Program and Vehicle...

253

Nano-photonic Light Trapping In Thin Film Solar Dennis M. Callahan Jr.  

E-Print Network [OSTI]

Nano-photonic Light Trapping In Thin Film Solar Cells Thesis by Dennis M. Callahan Jr. In Partial. Jeremy Munday for helping me get started on the thin-film GaAs project and for all the time we spent to thank Dr. Jonathan Grandidier for working closely with me for a couple years on the nano sphere solar

Winfree, Erik

254

Nanoparticle-induced light scattering for improved performance of quantum-well solar cells  

E-Print Network [OSTI]

performance of InP/InGaAsP quantum-well waveguide solar cells via light scattering from deposited dielectric of quantum wells to ensure high photon absorption efficiency and increased short-circuit current den- sity homojunction device by extending the absorption spectrum to longer wavelengths.6,7 We show here that nor- mally

Yu, Edward T.

255

A New Combustion Synthesis Method for GaN:Eu3+ and Ga2O3 :Eu3+  

E-Print Network [OSTI]

A New Combustion Synthesis Method for GaN:Eu3+ and Ga2O3 :Eu3+ Luminescent Powders G. A. Hirata1 between the precursors. The preparation of Eu-doped Ga2O3 powders was achieved using a new combustion)3 and Ga(NO3)3 as the precursors and hydrazine as (non-carbonaceous) fuel. A spontaneous combustion

McKittrick, Joanna

256

Control of the dephasing process due to many-body interactions among excitons by using non-Markovian effect in GaAs single quantum well  

SciTech Connect (OSTI)

We show the coherent control of dephasing process of exciton polarization due to heavy hole-heavy hole and heavy hole-light hole scatterings in a GaAs single quantum well. The memory time of the exction scattering is estimated as 0.47 ps.

Ogawa, Y.; Minami, F. [Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan)

2013-12-04T23:59:59.000Z

257

AlGaAs/GaAs photovoltaic converters for high power narrowband radiation  

SciTech Connect (OSTI)

AlGaAs/GaAs-based laser power PV converters intended for operation with high-power (up to 100 W/cm{sup 2}) radiation were fabricated by LPE and MOCVD techniques. Monochromatic (? = 809 nm) conversion efficiency up to 60% was measured at cells with back surface field and low (x = 0.2) Al concentration 'window'. Modules with a voltage of 4 V and the efficiency of 56% were designed and fabricated.

Khvostikov, Vladimir; Kalyuzhnyy, Nikolay; Mintairov, Sergey; Potapovich, Nataliia; Shvarts, Maxim; Sorokina, Svetlana; Andreev, Viacheslav [Ioffe Physical-Technical Institute, 26 Polytechnicheskaya, St. Petersburg, 194021 (Russian Federation); Luque, Antonio [Ioffe Physical-Technical Institute, 26 Polytechnicheskaya, St. Petersburg, 194021, Russia and Instituto de Energia Solar, Universidad Politecnica de Madrid, Madrid (Spain)

2014-09-26T23:59:59.000Z

258

Recent progress in InGaAsSb/GaSb TPV devices  

SciTech Connect (OSTI)

AstroPower is developing InGaAsSb thermophotovoltaic (TPV) devices. This photovoltaic cell is a two-layer epitaxial InGaAsSb structure formed by liquid-phase epitaxy on a GaSb substrate. The (direct) bandgap of the In{sub 1{minus}x}Ga{sub x}As{sub 1{minus}y}Sb{sub y} alloy is 0.50 to 0.55 eV, depending on its exact alloy composition (x,y); and is closely lattice-matched to the GaSb substrate. The use of the quaternary alloy, as opposed to a ternary alloy--such as, for example InGaAs/InP--permits low bandgap devices optimized for 1,000 to 1,500 C thermal sources with, at the same time, near-exact lattice matching to the GaSb substrate. Lattice matching is important since even a small degree of lattice mismatch degrades device performance and reliability and increases processing complexity. Internal quantum efficiencies as high as 95% have been measured at a wavelength of 2 microns. At 1 micron wavelengths, internal quantum efficiencies of 55% have been observed. The open-circuit voltage at currents of 0.3 A/cm{sup 2} is 0.220 volts and 0.280 V for current densities of 2 A/cm{sup 2}. Fill factors of 56% have been measured at 60 mA/cm{sup 2}. However, as current density increases there is some decrease in fill factor. The results to date show that the GaSb-based quaternary compounds provide a viable and high performance energy conversion solution for thermophotovoltaic systems operating with 1,000 to 1,500 C source temperatures.

Shellenbarger, Z.A.; Mauk, M.G.; DiNetta, L.C. [AstroPower, Inc., Newark, DE (United States); Charache, G.W. [Lockheed Martin Corp., Schenectady, NY (United States)

1996-05-01T23:59:59.000Z

259

Radio-frequency reflectometry on an undoped AlGaAs/GaAs single electron transistor  

SciTech Connect (OSTI)

Radio frequency reflectometry is demonstrated in a sub-micron undoped AlGaAs/GaAs device. Undoped single electron transistors (SETs) are attractive candidates to study single electron phenomena, due to their charge stability and robust electronic properties after thermal cycling. However, these devices require a large top-gate, which is unsuitable for the fast and sensitive radio frequency reflectometry technique. Here, we demonstrate that rf reflectometry is possible in an undoped SET.

MacLeod, S. J.; See, A. M.; Keane, Z. K.; Scriven, P.; Micolich, A. P.; Hamilton, A. R., E-mail: Alex.Hamilton@unsw.edu.au [School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Aagesen, M.; Lindelof, P. E. [Nanoscience Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen (Denmark)] [Nanoscience Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen (Denmark)

2014-01-06T23:59:59.000Z

260

Lattice-Mismatched GaAs/InGaAs Two-Junction Solar Cells by Direct Wafer Bonding  

SciTech Connect (OSTI)

Direct bonded interconnect between subcells of a lattice-mismatched III-V compound multijunction cell would enable dislocation-free active regions by confining the defect network needed for lattice mismatch accommodation to tunnel junction interfaces, while metamorphic growth inevitably results in less design flexibility and lower material quality than is desirable. The first direct-bond interconnected multijunction solar cell, a two-terminal monolithic GaAs/InGaAs two-junction solar cell, is reported and demonstrates viability of direct wafer bonding for solar cell applications. The tandem cell open-circuit voltage was approximately the sum of the subcell open-circuit voltages. This achievement shows direct bonding enables us to construct lattice-mismatched III-V multijunction solar cells and is extensible to an ultrahigh efficiency InGaP/GaAs/InGaAsP/InGaAs four-junction cell by bonding a GaAs-based lattice-matched InGaP/GaAs subcell and an InP-based lattice-matched InGaAsP/InGaAs subcell. The interfacial resistance experimentally obtained for bonded GaAs/InP smaller than 0.10 Ohm-cm{sup 2} would result in a negligible decrease in overall cell efficiency of {approx}0.02%, under 1-sun illumination.

Tanabe, K.; Aiken, D. J.; Wanlass, M. W.; Morral, A. F.; Atwater, H. A.

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
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261

Fractal quantum well heterostructures for broadband light emitters  

SciTech Connect (OSTI)

We examine carrier relaxation and radiative recombination in AlGaAs based near IR and AlGaInP based visible fractal quantum well heterostructures. Through temperature dependent photoluminescence, we demonstrate that enhanced population of higher lying energy levels can be achieved by varying the thickness of the layers in the fractal heterostructurd. This distribution of carriers results in room temperature emission over a relatively broad range of wavelengths: approximately 700--855 nm for AlGaAs structures and 575--650 nm for AlGaInP structures. Spectra are compared to theoretical calculations to evaluate the non-equilibrium nature of the carrier distributions. Time resolved photoluminescence measurements demonstrate an approximately linear relationship between the radiative decay time and the layer thickness of the structure. Correspondingly, integrated luminescence measurements at room temperature reveal a factor of four increase in the light output efficiency of the structure as the fractal layer thickness is increased from 50 {angstrom} to 400 {angstrom}. The applicability of these heterostructures to broadband LEDs is discussed.

Crawford, M.H.; Gourley, P.L.; Meissner, K.E.; Sinclair, M.B.; Jones, E.D.; Chow, W.W.; Schneider, R.P. Jr.

1994-12-31T23:59:59.000Z

262

Photonic crystal light source  

DOE Patents [OSTI]

A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

Fleming, James G. (Albuquerque, NM); Lin, Shawn-Yu (Albuquerque, NM); Bur, James A. (Corrales, NM)

2004-07-27T23:59:59.000Z

263

Point defect balance in epitaxial GaSb  

SciTech Connect (OSTI)

Positron annihilation spectroscopy in both conventional and coincidence Doppler broadening mode is used for studying the effect of growth conditions on the point defect balance in GaSb:Bi epitaxial layers grown by molecular beam epitaxy. Positron annihilation characteristics in GaSb are also calculated using density functional theory and compared to experimental results. We conclude that while the main positron trapping defect in bulk samples is the Ga antisite, the Ga vacancy is the most prominent trap in the samples grown by molecular beam epitaxy. The results suggest that the p–type conductivity is caused by different defects in GaSb grown with different methods.

Segercrantz, N., E-mail: natalie.segercrantz@aalto.fi; Slotte, J.; Makkonen, I.; Kujala, J.; Tuomisto, F. [Department of Applied Physics, Aalto University, P.O. Box 14100, FIN-00076 Aalto Espoo (Finland); Song, Y.; Wang, S. [Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Göteborg (Sweden); State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences 865 Changning Road, Shanghai 200050 (China)

2014-08-25T23:59:59.000Z

264

Light extraction from organic light-emitting diodes for lighting applications by sand-blasting  

E-Print Network [OSTI]

Light extraction from organic light-emitting diodes for lighting applications by sand@ust.hk Abstract: Light extraction from organic light-emitting diodes (OLEDs) by scattering the light is one of the effective methods for large-area lighting applications. In this paper, we present a very simple and cost

265

HIGH-EFFICIENCY NITRIDE-BASED SOLID-STATE LIGHTING  

SciTech Connect (OSTI)

In this semiannual report we summarize the progress obtained in the first six months with the support of DoE contract No.DE-FC26-01NT41203, entitled ''High-Efficiency Nitride-Based Solid-State Lighting''. The two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and Rensselaer Polytechnic Institute (led by Dr. N. Narendran), are pursuing the goals of this contract from thin film growth, characterization, and packaging standpoints. The UCSB team has made significant progress in the development of GaN vertical cavity surface-emitting lasers (VCSELs) as well as light-emitting diodes (LEDs) with AlGaN active regions emitting in the ultraviolet (UV). The Rensselaer team has developed target specifications for some of the key parameters for the proposed solid-state lighting system, including a luminous flux requirement matrix for various lighting applications, optimal spectral power distributions, and the performance characteristics of currently available commercial LEDs for eventual comparisons to the devices developed in the scope of this project.

Dr. Paul T. Fini; Prof. Shuji Nakamura

2002-04-30T23:59:59.000Z

266

HIGH-EFFICIENCY NITRIDE-BASED SOLID-STATE LIGHTING  

SciTech Connect (OSTI)

In this annual report we summarize the progress obtained in the first year with the support of DoE contract No.DE-FC26-01NT41203, entitled ''High-Efficiency Nitride-Based Solid-State Lighting''. The two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and Rensselaer Polytechnic Institute (led by Dr. N. Narendran), are pursuing the goals of this contract from thin film growth, characterization, and packaging standpoints. The UCSB team has made significant progress in the development of GaN vertical cavity surface-emitting lasers (VCSELs) as well as light-emitting diodes (LEDs) with AlGaN active regions emitting in the ultraviolet (UV). The Rensselaer team has developed target specifications for some of the key parameters for the proposed solid-state lighting system, including a luminous flux requirement matrix for various lighting applications, optimal spectral power distributions, and the performance characteristics of currently available commercial LEDs for eventual comparisons to the devices developed in the scope of this project.

Dr. Paul T. Fini; Prof. Shuji Nakamura

2002-09-01T23:59:59.000Z

267

SMART LIGHTING SYSTEMS ULTIMATE LIGHTING The Smart Lighting  

E-Print Network [OSTI]

Integration (Holistic Integrated Design) · Sensors as important as LEDs · Interconnected systems (human, building, grid) · Artistic Design Freedom · Lighting is Health, Entertainment, Information and Illumination Cost at any brightness · Chip level integrated electronics THE ERC RESEARCH COVERS THE ENTIRE SUPPLY

Linhardt, Robert J.

268

Reactive codoping of GaAlInP compound semiconductors  

DOE Patents [OSTI]

A GaAlInP compound semiconductor and a method of producing a GaAlInP compound semiconductor are provided. The apparatus and method comprises a GaAs crystal substrate in a metal organic vapor deposition reactor. Al, Ga, In vapors are prepared by thermally decomposing organometallic compounds. P vapors are prepared by thermally decomposing phospine gas, group II vapors are prepared by thermally decomposing an organometallic group IIA or IIB compound. Group VIB vapors are prepared by thermally decomposing a gaseous compound of group VIB. The Al, Ga, In, P, group II, and group VIB vapors grow a GaAlInP crystal doped with group IIA or IIB and group VIB elements on the substrate wherein the group IIA or IIB and a group VIB vapors produced a codoped GaAlInP compound semiconductor with a group IIA or IIB element serving as a p-type dopant having low group II atomic diffusion.

Hanna, Mark Cooper (Boulder, CO); Reedy, Robert (Golden, CO)

2008-02-12T23:59:59.000Z

269

The performance of double active region InGaAsP lasers  

SciTech Connect (OSTI)

In this paper the light-current characteristic and temperature behavior of the double-carrier-confinement (DCC) InGaAsP laser are shown largely to be determined by auger recombination. The carrier distributions in the two active regions, especially their relative fractions, play a major role in device behavior. A self-consistent, comprehensive numerical laser model is used to analyze a set of devices showing that superlinearity and possibly bistability are due to saturable absorption in the second active region and that a high characteristic temperature is usually tied with a higher threshold current density because of substantial Auger recombination rates in this type of device.

Champagne, A.; Maciejko, R. (Dept. of Engineering Physics, Ecole Polytechnique, Montreal, Quebec H3C 3A7 (CA)); Glinski, J.M. (Bell-Northern Research, Nepean, Ontario K1Y 4H7 (CA))

1991-10-01T23:59:59.000Z

270

Evaluation of GaN substrates grown in supercritical basic ammonia  

SciTech Connect (OSTI)

GaN crystals grown by the basic ammonothermal method were investigated for their use as substrates for device regrowth. X-ray diffraction analysis indicated that the substrates contained multiple grains while secondary ion mass spectroscopy (SIMS) revealed a high concentration of hydrogen, oxygen, and sodium. Despite these drawbacks, the emission from the light emitting diode structures grown by metal organic chemical vapor deposition on both the c-plane and m-plane epitaxial wafers was demonstrated. The SIMS depth profiles showed that the diffusion of the alkali metal from the substrate into the epitaxial film was small, especially in the m-direction.

Saito, Makoto; Yamada, Hisashi; Iso, Kenji; Sato, Hitoshi; Hirasawa, Hirohiko; Kamber, Derrick S.; Hashimoto, Tadao; Baars, Steven P. den; Speck, James S.; Nakamura, Shuji [Materials Department, University of California, Santa Barbara, California 93106 (United States)

2009-02-02T23:59:59.000Z

271

Nano-scale characterization of GaAsP/GaAs strained superlattice structure by nano-beam electron diffraction  

SciTech Connect (OSTI)

Distribution of lattice strain in a GaAsP/GaAs superlattice with a periodicity of 10?nm thickness, deposited on a 100?nm GaAs basal layer has been measured by nano-beam electron diffraction. The superlattice on the (001) plane of the basal GaAs layer shows a constant lattice strain from the bottom to the top layers, whereas the superlattice on the basal GaAs surface sloped by 16° from the (001) plane shows a variation of the lattice strain and crystal orientation. The difference of the strain distributions was discussed from the viewpoint of average strain. This tilt was explained by an atomistic model.

Jin, Xiuguang [Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Nakahara, Hirotaka [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Saitoh, Koh; Tanaka, Nobuo [EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Takeda, Yoshikazu [Nagoya Industrial Science Research Institute, Nagoya 464-0819 (Japan); Aichi Synchrotron Radiation Center, Aichi Science and Technology Foundation, Seto 489-0965 (Japan)

2014-03-17T23:59:59.000Z

272

Arnold Schwarzenegger LIGHTING RESEARCH PROGRAM  

E-Print Network [OSTI]

Project Summaries ELEMENT 2: ADVANCE LIGHTING TECHNOLOGIES PROJECT 2.1 LIGHT EMITTING DIODE (LED light emitting diodes (LED) technology for general lighting applications by developing a task lamp

273

Manipulation of emission energy in GaAs/AlGaAs core-shell nanowires with radial heterostructure  

SciTech Connect (OSTI)

Photoluminescence was studied in GaAs/AlGaAs nanowires (NWs) with different radial heterostructures. We demonstrated that manipulation of the emission energy may be achieved by appropriate choice of the shell structure. The emission at highest energy is generated in the NWs with tunneling thin AlGaAs inner shell and thin GaAs outer shell due to recombination of the photoexcited electrons confined in the outer shell with the holes in the core. Lower energy emission was shown to occur in the NWs with thick outer shell grown in the form of a short-period GaAs/AlGaAs multiple quantum well structure. In this case, the tunneling probability through the multiple quantum wells controls the energy emitted by the NWs. The doping of core results in dominated low energy emission from the GaAs core.

Barbosa, B. G.; Arakaki, H.; Souza, C. A. de; Pusep, Yu. A. [Instituto de Fisica de São Carlos, Universidade de São Paulo, 13560-970 Sao Carlos, SP (Brazil)

2014-03-21T23:59:59.000Z

274

Enhancement of current collection in epitaxial lift-off InAs/GaAs quantum dot thin film solar cell and concentrated photovoltaic study  

SciTech Connect (OSTI)

We report the fabrication of a thin film InAs/GaAs quantum dot solar cell (QD cell) by applying epitaxial lift-off (ELO) approach to the GaAs substrate. We confirmed significant current collection enhancement (?0.91?mA/cm{sup 2}) in the ELO-InAs QD cell within the wavelength range of 700?nm–900?nm when compared to the ELO-GaAs control cell. This is almost six times of the sub-GaAs bandgap current collection (?0.16?mA/cm{sup 2}) from the wavelength range of 900?nm and beyond, we also confirmed the ELO induced resonance cavity effect was able to increase the solar cell efficiency by increasing both the short circuit current and open voltage. The electric field intensity of the resonance cavity formed in the ELO film between the Au back reflector and the GaAs front contact layer was analyzed in detail by finite-differential time-domain (FDTD) simulation. We found that the calculated current collection enhancement within the wavelength range of 700?nm–900?nm was strongly influenced by the size and shape of InAs QD. In addition, we performed concentrated light photovoltaic study and analyzed the effect of intermediate states on the open voltage under varied concentrated light intensity for the ELO-InAs QD cell.

Sogabe, Tomah, E-mail: sogabe@mbe.rcast.u-tokyo.ac.jp; Shoji, Yasushi; Tamayo, Efrain; Okada, Yoshitaka [Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8504 (Japan); Mulder, Peter; Schermer, John [Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands)

2014-09-15T23:59:59.000Z

275

New Light Sources for Tomorrow's Lighting Designs  

E-Print Network [OSTI]

, pioneered for headlam~for the automotive industry, has led to the development of halo en capsule lamps for general lighting. The original90-watt family PAR 38 lamps using tungsten halogen capsules produces the sa amount of useful light in the beam as a I... quartz PAR lamps with similar benefi . Each of these tungsten halogen capsule PAR wattages are av ilable in narrow spot, spot, and flood beam patterns. The most recent developments in the PAR halogen psule family include two entirely new lamp designs...

Krailo, D. A.

276

National Synchrotron Light Source  

ScienceCinema (OSTI)

A tour of Brookhaven's National Synchrotron Light Source (NSLS), hosted by Associate Laboratory Director for Light Sources, Stephen Dierker. The NSLS is one of the world's most widely used scientific research facilities, hosting more than 2,500 guest researchers each year. The NSLS provides intense beams of infrared, ultraviolet, and x-ray light for basic and applied research in physics, chemistry, medicine, geophysics, environmental, and materials sciences.

BNL

2009-09-01T23:59:59.000Z

277

LED Lighting Retrofit  

E-Print Network [OSTI]

? Municipal Street Lighting Consortium ? American Public Power Association (APPA) ? Demonstration in Energy Efficiency Development (DEED) ? Source of funding and database of completed LED roadway projects 6 Rules of the Road ESL-KT-11-11-57 CATEE 2011..., 2011 ? 9 Solar-Assisted LED Case Study LaQuinta Hotel, Cedar Park, Texas ? Utilizes 18 - ActiveLED Solar-Assisted Parking Lot Lights ? Utilizes ?power management? to extend battery life while handling light output ? Reduces load which reduces PV...

Shaw-Meadow, N.

2011-01-01T23:59:59.000Z

278

High efficiency incandescent lighting  

DOE Patents [OSTI]

Incandescent lighting structure. The structure includes a thermal emitter that can, but does not have to, include a first photonic crystal on its surface to tailor thermal emission coupled to, in a high-view-factor geometry, a second photonic filter selected to reflect infrared radiation back to the emitter while passing visible light. This structure is highly efficient as compared to standard incandescent light bulbs.

Bermel, Peter; Ilic, Ognjen; Chan, Walker R.; Musabeyoglu, Ahmet; Cukierman, Aviv Ruben; Harradon, Michael Robert; Celanovic, Ivan; Soljacic, Marin

2014-09-02T23:59:59.000Z

279

Total Light Management  

Broader source: Energy.gov [DOE]

Presentation covers total light management, and is given at the Spring 2010 Federal Utility Partnership Working Group (FUPWG) meeting in Providence, Rhode Island.

280

Lighting Technology Panel  

Broader source: Energy.gov [DOE]

Presentation covers the Lighting Technology Panel for the Federal Utility Partnership Working Group (FUPWG) meeting, held on November 18-19, 2009. 

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Comparing Light Bulbs  

Broader source: Energy.gov [DOE]

In this exercise, students will use a light to demonstrate the difference between being energy-efficient and energy-wasteful, and learn what energy efficiency means.

282

Solid-State Lighting  

Broader source: Energy.gov (indexed) [DOE]

research and design. Quality LED luminaires require program designed to successfully move solid-state lighting precise design of several components -LED arrays, electronic into the...

283

Composition dependent valence band order in c-oriented wurtzite AlGaN layers  

SciTech Connect (OSTI)

The valence band order of polar wurtzite aluminum gallium nitride (AlGaN) layers is analyzed for a dense series of samples, grown heteroepitaxially on sapphire substrates, covering the complete composition range. The excitonic transition energies, found by temperature dependent photoluminescence (PL) spectroscopy, were corrected to the unstrained state using input from X-ray diffraction. k?p theory yields a critical relative aluminum concentration x{sub c}=(0.09±0.05) for the crossing of the uppermost two valence bands for strain free material, shifting to higher values for compressively strained samples, as supported by polarization dependent PL. The analysis of the strain dependent valence band crossing reconciles the findings of other research groups, where sample strain was neglected. We found a bowing for the energy band gap to the valence band with ?{sub 9} symmetry of b{sub ?{sub 9}}=0.85eV, and propose a possible bowing for the crystal field energy of b{sub cf}=?0.12eV. A comparison of the light extraction efficiency perpendicular and parallel to the c axis of Al{sub x}Ga{sub 1-x}N/Al{sub y}Ga{sub 1-y}N quantum well structures is discussed for different compositions.

Neuschl, B., E-mail: benjamin.neuschl@uni-ulm.de; Helbing, J.; Knab, M.; Lauer, H.; Madel, M.; Thonke, K. [Institute of Quantum Matter / Semiconductor Physics Group, University of Ulm, Albert-Einstein-Allee 45, 89069 Ulm (Germany); Meisch, T.; Forghani, K.; Scholz, F. [Institute of Optoelectronics, University of Ulm, Albert-Einstein-Allee 45, 89069 Ulm (Germany); Feneberg, M. [Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg (Germany)

2014-09-21T23:59:59.000Z

284

0.7-eV GaInAs Junction for a GaInP/GaAs/GaInAs(1eV)/GaInAs(0.7eV) Four-Junction Solar Cell  

SciTech Connect (OSTI)

We discuss recent developments in III-V multijunction solar cells, focusing on adding a fourth junction to the Ga{sub 0.5}In{sub 0.5} P/GaAs/Ga{sub 0.75}In{sub 0.25}As inverted three-junction cell. This cell, grown inverted on GaAs so that the lattice-mismatched Ga{sub 0.75}In{sub 0.25}As third junction is the last one grown, has demonstrated 38% efficiency, and 40% is likely in the near future. To achieve still further gains, a lower-bandgap Ga{sub x}In{sub 1-x}As fourth junction could be added to the three-junction structure for a four-junction cell whose efficiency could exceed 45% under concentration. Here, we present the initial development of the Ga{sub x}In{sub 1-x}As fourth junction. Junctions of various bandgaps ranging from 0.88 to 0.73 eV were grown, in order to study the effect of the different amounts of lattice mismatch. At a bandgap of 0.88 eV, junctions were obtained with very encouraging {approx}80% quantum efficiency, 57% fill factor, and 0.36 eV open-circuit voltage. The device performance degrades with decreasing bandgap (i.e., increasing lattice mismatch). We model the four-junction device efficiency vs. fourth junction bandgap to show that an 0.7-eV fourth-junction bandgap, while optimal if it could be achieved in practice, is not necessary; an 0.9-eV bandgap would still permit significant gains in multijunction cell efficiency while being easier to achieve than the lower-bandgap junction.

Friedman, D. J.; Geisz, J. F.; Norman, A. G.; Wanlass, M. W.; Kurtz, S. R.

2006-01-01T23:59:59.000Z

285

New red phosphor for near-ultraviolet light-emitting diodes with high color-purity  

SciTech Connect (OSTI)

New red phosphors, Na{sub 5}Eu(MoO{sub 4}){sub 4} doped with boron oxide were prepared by the solid-state reaction. Their structure and photo-luminescent properties were investigated. With the introduction of boron oxide, the red emission intensity of the phosphors under 395 nm excitation is strengthened, with high color-purity (x = 0.673, y = 0.327). The single red light-emitting diode was obtained by combining InGaN chip with the red phosphor, bright red light can be observed by naked eyes from the red light-emitting diodes under a forward bias of 20 mA.

Wang, Zhengliang, E-mail: wzhl_ww@yahoo.com.cn [School of Chemistry and Biotechnology, Yunnan Nationalities University, Kunming, Yunnan 650031 (China)] [School of Chemistry and Biotechnology, Yunnan Nationalities University, Kunming, Yunnan 650031 (China); He, Pei; Wang, Rui [School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275 (China)] [School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275 (China); Zhao, Jishou [School of Chemistry and Biotechnology, Yunnan Nationalities University, Kunming, Yunnan 650031 (China)] [School of Chemistry and Biotechnology, Yunnan Nationalities University, Kunming, Yunnan 650031 (China); Gong, Menglian [School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275 (China)] [School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275 (China)

2010-02-15T23:59:59.000Z

286

OpenGL Lighting 13. OpenGL Lighting  

E-Print Network [OSTI]

OpenGL Lighting 13. OpenGL Lighting · Overview of Lighting in OpenGL In order for lighting to have an effect in OpenGL, two things are required: A light An object to be lit Lights can be set to any color determine how they reflect the light which hits them. The color(s) of an object is determined

McDowell, Perry

287

Efficiency enhancement of InGaN/GaN solar cells with nanostructures  

SciTech Connect (OSTI)

We demonstrate InGaN/GaN multi-quantum-well solar cells with nanostructures operating at a wavelength of 520?nm. Nanostructures with a periodic nanorod or nanohole array are fabricated by means of modified nanosphere lithography. Under 1 sun air-mass 1.5 global spectrum illumination, a fill factor of 50 and an open circuit voltage of 1.9?V are achieved in spite of very high indium content in InGaN alloys usually causing degradation of crystal quality. Both the nanorod array and the nanohole array significantly improve the performance of solar cells, while a larger enhancement is observed for the nanohole array, where the conversion efficiency is enhanced by 51%.

Bai, J.; Yang, C. C.; Athanasiou, M.; Wang, T. [Department of Electronics and Electrical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

2014-02-03T23:59:59.000Z

288

Graphene in ohmic contact for both n-GaN and p-GaN  

SciTech Connect (OSTI)

The wrinkles of single layer graphene contacted with either n-GaN or p-GaN were found both forming ohmic contacts investigated by conductive atomic force microscopy. The local I–V results show that some of the graphene wrinkles act as high-conductive channels and exhibiting ohmic behaviors compared with the flat regions with Schottky characteristics. We have studied the effects of the graphene wrinkles using density-functional-theory calculations. It is found that the standing and folded wrinkles with zigzag or armchair directions have a tendency to decrease or increase the local work function, respectively, pushing the local Fermi level towards n- or p-type GaN and thus improving the transport properties. These results can benefit recent topical researches and applications for graphene as electrode material integrated in various semiconductor devices.

Zhong, Haijian; Liu, Zhenghui; Shi, Lin; Xu, Gengzhao; Fan, Yingmin; Huang, Zengli [Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Wang, Jianfeng; Ren, Guoqiang; Xu, Ke, E-mail: kxu2006@sinano.ac.cn [Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Suzhou Nanowin Science and Technology Co., Ltd., Suzhou 215123 (China)

2014-05-26T23:59:59.000Z

289

Direct observation of Ga-rich microdomains in crack-free AlGaN grown on patterned GaNsapphire substrates  

E-Print Network [OSTI]

.e., a homogeneous aluminum content, is found near the sample surface. However, the strong rise of quantum efficiency for AlGaN because the Al alloys also nucleate on the mask materials. Recently, growth on patterned structured into a periodic grid of trenches and terraces along 1100 . Prior to the final AlGaN ( Al 0

Nabben, Reinhard

290

Measurement of electron beam polarization from unstrained GaAs via two-photon photoemission  

SciTech Connect (OSTI)

Two-photon absorption of 1560 nm light was used to generate polarized electron beams from unstrained GaAs photocathodes of varying thickness: 625 {mu}m, 0.32 {mu}m, and 0.18 {mu}m. For each photocathode, the degree of spin polarization of the photoemitted beam was less than 50%, contradicting earlier predictions based on simple quantum mechanical selection rules for spherically-symmetric systems but consistent with the more sophisticated model of Bhat et al. (Phys. Rev. B 71 (2005) 035209). Polarization via two-photon absorption was the highest from the thinnest photocathode sample and comparable to that obtained via one-photon absorption (using 778 nm light), with values 40.3 +- 1.0% and 42.6 +- 1.0%, respectively.

McCarter, James L. [Univ. of Virginia, Charlottesville, VA (United States); Afanasev, A. [George Washington Univ., Washingon, DC (United States); Gay, T. J. [Univ. of Nebraska, Lincoln, NE (United States); Hansknecht, John C. [JLAB, Newport News, VA (United States); Kechiantz, A. [George Washington Univ., Washingon, DC (United States); Poelker, B. Matthew [JLAB, Newport News, VA (United States)

2014-02-01T23:59:59.000Z

291

Fano Resonance in GaAs 2D Photonic Crystal Nanocavities  

SciTech Connect (OSTI)

We report the results of polarization resolved reflectivity experiments in GaAs air-bridge photonic crystals with L3 cavities. We show that the fundamental L3 cavity mode changes, in a controlled way, from a Lorentzian symmetrical lineshape to an asymmetrical form when the linear polarization of the incident light is rotated in the plane of the crystal. The different lineshapes are well fitted by the Fano asymmetric equation, implying that a Fano resonance is present in the reflectivity. We use the scattering matrix method to model the Fano interference between a localized discrete state (the cavity fundamental mode) and a background of continuum states (the light reflected from the crystal slab in the vicinity of the cavity) with very good agreement with the experimental data.

Valentim, P. T.; Guimaraes, P.S. S. [Departamento de Fisica, Universidade Federal de Minas Gerais, Belo Horizonte (Brazil); Instituto Nacional de Ciencia e Tecnologia de Nanodispositivos Semicondutores - INCT-DISSE (Brazil); Luxmoore, I. J.; Szymanski, D.; Whittaker, D. M.; Fox, A. M.; Skolnick, M. S. [Department of Physics and Astronomy, University of Sheffield, Sheffield (United Kingdom); Vasco, J. P. [Instituto de Fisica, Universidad de Antioquia, Medellin (Colombia); Vinck-Posada, H. [Departamento de Fisica, Facultad de Ciencias, Universidad Nacional de Colombia, Bogota (Colombia)

2011-12-23T23:59:59.000Z

292

Thickness dependence of magnetic anisotropy in thin Ni films electrodeposited onto the (011) and (001) surfaces of n-GaAs  

SciTech Connect (OSTI)

Brillouin light scattering from thermal spin waves has been exploited to investigate the thickness dependence of magnetic anisotropy of Ni films, with thickness in the range 7-35 nm, grown by electrodeposition onto either (011)- or (001)-GaAs substrates. In the former case, Ni films exhibit a well-defined in-plane uniaxial anisotropy induced by the symmetry of the substrate. In the case of the (001)-GaAs substrate, instead, the magnetic anisotropy results from a combination of both a fourfold and a twofold contribution. The physical mechanisms responsible for the observed anisotropy, as well as its dependence on film thickness, are discussed in detail.

Gubbiotti, G.; Carlotti, G.; Tacchi, S.; Liu, Y.-K.; Scheck, C.; Schad, R.; Zangari, G. [INFM CRS-SOFT, c/o Universita di Roma 'La Sapienza', I-00185, Rome (Italy); INFM UdR-Perugia, c/o Dipartimento di Fisica, Universita di Perugia, Via A. Pascoli, 06123 Perugia (Italy); INFM-National Center for nanoStructures and bioSystem at Surfaces (S3) Modena, and Dipartimento di Fisica, Universita di Perugia, Via A. Pascoli, 06123 Perugia (Italy); IINFM UdR-Perugia, Dipartimento di Fisica, Universita di Perugia, Via A. Pascoli, 06123 Perugia (Italy); MINT Center, University of Alabama, Tuscaloosa Alabama 35401 (United States); Department of Materials Science and Engineering and Center for Electrochemical Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States)

2005-05-15T23:59:59.000Z

293

Light intensity compressor  

DOE Patents [OSTI]

In a system for recording images having vastly differing light intensities over the face of the image, a light intensity compressor is provided that utilizes the properties of twisted nematic liquid crystals to compress the image intensity. A photoconductor or photodiode material that is responsive to the wavelength of radiation being recorded is placed adjacent a layer of twisted nematic liquid crystal material. An electric potential applied to a pair of electrodes that are disposed outside of the liquid crystal/photoconductor arrangement to provide an electric field in the vicinity of the liquid crystal material. The electrodes are substantially transparent to the form of radiation being recorded. A pair of crossed polarizers are provided on opposite sides of the liquid crystal. The front polarizer linearly polarizes the light, while the back polarizer cooperates with the front polarizer and the liquid crystal material to compress the intensity of a viewed scene. Light incident upon the intensity compressor activates the photoconductor in proportion to the intensity of the light, thereby varying the field applied to the liquid crystal. The increased field causes the liquid crystal to have less of a twisting effect on the incident linearly polarized light, which will cause an increased percentage of the light to be absorbed by the back polarizer. The intensity of an image may be compressed by forming an image on the light intensity compressor.

Rushford, Michael C. (Livermore, CA)

1990-01-01T23:59:59.000Z

294

Splayed mirror light pipes  

SciTech Connect (OSTI)

An expression is given for the transmission of the rectangular-section mirror light pipe. The expression is used to model throughputs for simulated solar conditions over a calender year. It is found that the splaying of a mirror light pipe results in a significant increase in throughputs particularly in winter months. (author)

Swift, P.D. [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)

2010-02-15T23:59:59.000Z

295

Explosively pumped laser light  

DOE Patents [OSTI]

A single shot laser pumped by detonation of an explosive in a shell casing. The shock wave from detonation of the explosive causes a rare gas to luminesce. The high intensity light from the gas enters a lasing medium, which thereafter outputs a pulse of laser light to disable optical sensors and personnel.

Piltch, Martin S. (Los Alamos, NM); Michelotti, Roy A. (Los Alamos, NM)

1991-01-01T23:59:59.000Z

296

Reducing home lighting expenses  

SciTech Connect (OSTI)

Ways to reduce lighting expenses are summarized. These include: turning off lights when not in use; keeping fixtures and lamps clean; replacing lamps with more efficient types; using three-way bulbs; use of daylighting; buying fewer lamps and reducing lamp wattage; consider repainting rooms; replacing recessed fixtures with tracklighting; and using efficient lamps for outdoor use. (MCW)

Aimone, M.A.

1981-02-01T23:59:59.000Z

297

GaAs single quantum dot embedded into AlGaAs nanowire  

SciTech Connect (OSTI)

We report on a study of the photoluminescence spectra taken from quasi one-dimensional and quasi zero-dimensional semiconductor heterostructures. The structures were grown by molecular-beam epitaxy in (111) direction and were cylindrical nanowires based on AlGaAs, of 20 - 50 nm in diameter and 0.5 - 1 ?m in length. Inside the nanowires contain one or two GaAs quantum dots, of 2 nm thick and 15 - 45 nm in diameter. We studied a single nanowire. The photoluminescence and photoluminescence excitation spectra were registered as a function of the intensity of optical excitation.

Kochereshko, V. P.; Kats, V. N. [A.F.Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021, St. Petersburg, Russia and Spin Optics Laboratory, Saint Petersburg State University, Ul'yanovskaya 1, Petrodvorets, St. Petersburg, 198904 (Russian Federation); Platonov, A. V. [A.F.Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021, St. Petersburg (Russian Federation); Cirlin, G. E.; Bouravleuv, A. D.; Samsonenko, Yu. B. [A.F.Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021, St. Petersburg, Russia and St. Petersburg Academic University of the RAS Khlopina 8/3, 195220, St. Petersburg (Russian Federation); Besombes, L.; Mariette, H. [CEA-CNRS group Nanophysique et Semiconducteurs, CEA, INAC, SP2M, and Institut Néel, 17 rue des Martyrs, F-38054 Grenoble (France)

2013-12-04T23:59:59.000Z

298

Wavelength limits for InGaN quantum wells on GaN  

SciTech Connect (OSTI)

The emission wavelength of coherently strained InGaN quantum wells (QW) is limited by the maximum thickness before relaxation starts. For high indium contents x>40% the resulting wavelength decreases because quantum confinement dominates. For low indium content x<40% the electron hole wave function overlap (and hence radiative emission) is strongly reduced with increasing QW thickness due to the quantum confined Stark effect and imposes another limit. This results in a maximum usable emission wavelength at around 600?nm for QWs with 40%-50% indium content. Relaxed InGaN buffer layers could help to push this further, especially on non- and semi-polar orientations.

Pristovsek, Markus, E-mail: markus@pristovsek.de [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)] [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)

2013-06-17T23:59:59.000Z

299

Application of the ASME code in the design of the GA-4 and GA-9 casks  

SciTech Connect (OSTI)

General Atomics (GA) is developing two spent fuel shipping casks for transport by legal weight truck (LWT). The casks are designed to the loading, environmental conditions and safety requirements defined in Title 10 of the Code of Federal Regulations, Part 71 (10CFR71). To ensure that all components of the cask meet the 10CFR71 rules, GA established structural design criteria for each component based on NRC Regulatory Guides and the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). This paper discusses the criteria used for different cask components, how they were applied and the conservatism and safety margins built into the criteria and assumption.

Mings, W.J. (USDOE Idaho Field Office, Idaho Falls, ID (United States)); Koploy, M.A. (General Atomics, San Diego, CA (United States))

1992-01-01T23:59:59.000Z

300

Application of the ASME code in the design of the GA-4 and GA-9 casks  

SciTech Connect (OSTI)

General Atomics (GA) is developing two spent fuel shipping casks for transport by legal weight truck (LWT). The casks are designed to the loading, environmental conditions and safety requirements defined in Title 10 of the Code of Federal Regulations, Part 71 (10CFR71). To ensure that all components of the cask meet the 10CFR71 rules, GA established structural design criteria for each component based on NRC Regulatory Guides and the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). This paper discusses the criteria used for different cask components, how they were applied and the conservatism and safety margins built into the criteria and assumption.

Mings, W.J. [USDOE Idaho Field Office, Idaho Falls, ID (United States); Koploy, M.A. [General Atomics, San Diego, CA (United States)

1992-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Origins of ion irradiation-induced Ga nanoparticle motion on GaAs surfaces  

SciTech Connect (OSTI)

We have examined the origins of ion irradiation-induced nanoparticle (NP) motion. Focused-ion-beam irradiation of GaAs surfaces induces random walks of Ga NPs, which are biased in the direction opposite to that of ion beam scanning. Although the instantaneous NP velocities are constant, the NP drift velocities are dependent on the off-normal irradiation angle, likely due to a difference in surface non-stoichiometry induced by the irradiation angle dependence of the sputtering yield. It is hypothesized that the random walks are initiated by ion irradiation-induced thermal fluctuations, with biasing driven by anisotropic mass transport.

Kang, M.; Wu, J. H.; Chen, H. Y.; Thornton, K.; Goldman, R. S. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Sofferman, D. L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, Adelphi University, Garden City, New York 11530-0701 (United States); Beskin, I. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)] [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

2013-08-12T23:59:59.000Z

302

Temperature dependency of the emission properties from positioned In(Ga)As/GaAs quantum dots  

SciTech Connect (OSTI)

In this letter we study the influence of temperature and excitation power on the emission linewidth from site-controlled InGaAs/GaAs quantum dots grown on nanoholes defined by electron beam lithography and wet chemical etching. We identify thermal electron activation as well as direct exciton loss as the dominant intensity quenching channels. Additionally, we carefully analyze the effects of optical and acoustic phonons as well as close-by defects on the emission linewidth by means of temperature and power dependent micro-photoluminescence on single quantum dots with large pitches.

Braun, T.; Schneider, C.; Maier, S.; Forchel, A.; Höfling, S.; Kamp, M. [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074, Würzburg (Germany); Igusa, R.; Iwamoto, S.; Arakawa, Y. [University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

2014-09-15T23:59:59.000Z

303

AlGaAs/GaAs quantum well infrared detectors and modulators  

E-Print Network [OSTI]

to the quantum well. This optical transition wavelength lies in the mid infrared region of the spectrum. To get a more realistic picture of the optical transition in a 1-D quantum well, the non-parabolicity of the conduction band of GaAs is taken... into consideration. Further it is seen that with the change in temperature and doping concentration the width and peak of the absorption curve also changes. Based on the above calculations and results an AIGaAs/GaAs quantum well infrared photodetector...

Dave, Digant Praful

1990-01-01T23:59:59.000Z

304

Radiation Hard AlGaN Detectors and Imager  

SciTech Connect (OSTI)

Radiation hardness of AlGaN photodiodes was tested using a 65 MeV proton beam with a total proton fluence of 3x10{sup 12} protons/cm{sup 2}. AlGaN Deep UV Photodiode have extremely high radiation hardness. These new devices have mission critical applications in high energy density physics (HEDP) and space explorations. These new devices satisfy radiation hardness requirements by NIF. NSTec is developing next generation AlGaN optoelectronics and imagers.

None

2012-05-01T23:59:59.000Z

305

VIRTUAL LIGHT: DIGITALLY-GENERATED LIGHTING FOR VIDEO CONFERENCING APPLICATIONS  

E-Print Network [OSTI]

VIRTUAL LIGHT: DIGITALLY-GENERATED LIGHTING FOR VIDEO CONFERENCING APPLICATIONS Andrea Basso method to improve the lighting conditions of a real scene or video sequence. In particular we concentrate on modifying real light sources intensities and inserting virtual lights into a real scene viewed from a fixed

Fisher, Kathleen

306

Lighting affects appearance LightSource emits photons  

E-Print Network [OSTI]

1 Lighting affects appearance #12;2 LightSource emits photons Photons travel in a straight line). And then some reach the eye/camera. #12;3 Reflectance Model how objects reflect light. Model light sources Algorithms for computing Shading: computing intensities within polygons Determine what light strikes what

Jacobs, David

307

Inductively Coupled Plasma and Electron Cyclotron Resonance Plasma Etching of InGaAlP Compound Semiconductor System  

SciTech Connect (OSTI)

Current and future generations of sophisticated compound semiconductor devices require the ability for submicron scale patterning. The situation is being complicated since some of the new devices are based on a wider diversity of materials to be etched. Conventional IUE (Reactive Ion Etching) has been prevalent across the industry so far, but has limitations for materials with high bond strengths or multiple elements. IrI this paper, we suggest high density plasmas such as ECR (Electron Cyclotron Resonance) and ICP (Inductively Coupled Plasma), for the etching of ternary compound semiconductors (InGaP, AIInP, AlGaP) which are employed for electronic devices like heterojunction bipolar transistors (HBTs) or high electron mobility transistors (HEMTs), and photonic devices such as light-emitting diodes (LEDs) and lasers. High density plasma sources, opeiating at lower pressure, are expected to meet target goals determined in terms of etch rate, surface morphology, surface stoichiometry, selectivity, etc. The etching mechanisms, which are described in this paper, can also be applied to other III-V (GaAs-based, InP-based) as well as III-Nitride since the InGaAIP system shares many of the same properties.

Abernathy, C.R.; Hobson, W.S.; Hong, J.; Lambers, E.S.; Pearton, S.J.; Shul, R.J.

1998-11-04T23:59:59.000Z

308

Nitrogen-concentration control in GaNAs/AlGaAs quantum wells using nitrogen ?-doping technique  

SciTech Connect (OSTI)

GaNAs/Al{sub 0.35}Ga{sub 0.65}As multiple quantum wells (MQWs) with nitrogen ?-doping were fabricated on GaAs (100) substrates by plasma-assisted molecular beam epitaxy. High controllability of nitrogen-concentrations in the MQWs was achieved by tuning nitrogen ?-doping time. The maximum nitrogen concentration in the MQWs was 2.8%. The MQWs exhibit intense, narrow photoluminescence emission.

Mano, Takaaki; Jo, Masafumi; Kuroda, Takashi; Noda, Takeshi; Sugimoto, Yoshimasa; Sakuma, Yoshiki [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Elborg, Martin; Sakoda, Kazuaki [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan and Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan)

2014-05-15T23:59:59.000Z

309

Phosphor-free nanopyramid white light-emitting diodes grown on (101{sup ¯}1) planes using nanospherical-lens photolithography  

SciTech Connect (OSTI)

We reported a high-efficiency and low-cost nano-pattern method, the nanospherical-lens photolithography technique, to fabricate a SiO{sub 2} mask for selective area growth. By controlling the selective growth, we got a highly ordered hexagonal nanopyramid light emitting diodes with InGaN/GaN quantum wells grown on nanofacets, demonstrating an electrically driven phosphor-free white light emission. We found that both the quantum well width and indium incorporation increased linearly along the (101{sup ¯}1) planes towards the substrate and the perpendicular direction to the (101{sup ¯}1) planes as well. Such spatial distribution was responsible for the broadband emission. Moreover, using cathodoluminescence techniques, it was found that the blue emission originated from nanopyramid top, resembling the quantum dots, green emission from the InGaN quantum wells layer at the middle of sidewalls, and yellow emission mainly from the bottom of nanopyramid ridges, similar to the quantum wires.

Wu, Kui [State Key Laboratory of Solid-State Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China) [State Key Laboratory of Solid-State Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Department of Electronic Engineering, Tsinghua National Laboratory for Information Science and Technology/State Key Lab on Integrated Optoelectronics, Tsinghua University, Beijing 100084 (China); Wei, Tongbo, E-mail: tbwei@semi.ac.cn; Wei, Xuecheng; Zheng, Haiyang; Chen, Yu; Lu, Hongxi; Wang, Junxi; Li, Jinmin [State Key Laboratory of Solid-State Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)] [State Key Laboratory of Solid-State Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Lan, Ding [National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080 (China)] [National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080 (China); Huang, Kai [Platform of Characterization and Test, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215000 (China)] [Platform of Characterization and Test, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215000 (China); Luo, Yi [Department of Electronic Engineering, Tsinghua National Laboratory for Information Science and Technology/State Key Lab on Integrated Optoelectronics, Tsinghua University, Beijing 100084 (China)] [Department of Electronic Engineering, Tsinghua National Laboratory for Information Science and Technology/State Key Lab on Integrated Optoelectronics, Tsinghua University, Beijing 100084 (China)

2013-12-09T23:59:59.000Z

310

Green Light Pulse Oximeter  

DOE Patents [OSTI]

A reflectance pulse oximeter that determines oxygen saturation of hemoglobin using two sources of electromagnetic radiation in the green optical region, which provides the maximum reflectance pulsation spectrum. The use of green light allows placement of an oximetry probe at central body sites (e.g., wrist, thigh, abdomen, forehead, scalp, and back). Preferably, the two green light sources alternately emit light at 560 nm and 577 nm, respectively, which gives the biggest difference in hemoglobin extinction coefficients between deoxyhemoglobin, RHb, and oxyhemoglobin, HbO.sub.2.

Scharf, John Edward (Oldsmar, FL)

1998-11-03T23:59:59.000Z

311

White light velocity interferometer  

DOE Patents [OSTI]

The invention is a technique that allows the use of broadband and incoherent illumination. Although denoted white light velocimetry, this principle can be applied to any wave phenomenon. For the first time, powerful, compact or inexpensive sources can be used for remote target velocimetry. These include flash and arc lamps, light from detonations, pulsed lasers, chirped frequency lasers, and lasers operating simultaneously in several wavelengths. The technique is demonstrated with white light from an incandescent source to measure a target moving at 16 m/s.

Erskine, David J. (Oakland, CA)

1997-01-01T23:59:59.000Z

312

White light velocity interferometer  

DOE Patents [OSTI]

The invention is a technique that allows the use of broadband and incoherent illumination. Although denoted white light velocimetry, this principle can be applied to any wave phenomenon. For the first time, powerful, compact or inexpensive sources can be used for remote target velocimetry. These include flash and arc lamps, light from detonations, pulsed lasers, chirped frequency lasers, and lasers operating simultaneously in several wavelengths. The technique is demonstrated with white light from an incandescent source to measure a target moving at 16 m/s. 41 figs.

Erskine, D.J.

1997-06-24T23:59:59.000Z

313

White light velocity interferometer  

DOE Patents [OSTI]

The invention is a technique that allows the use of broadband and incoherent illumination. Although denoted white light velocimetry, this principle can be applied to any wave phenomenon. For the first time, powerful, compact or inexpensive sources can be used for remote target velocimetry. These include flash and arc lamps, light from detonations, pulsed lasers, chirped frequency lasers, and lasers operating simultaneously in several wavelengths. The technique is demonstrated with white light from an incandescent source to measure a target moving at 16 m/s.

Erskine, David J. (Oakland, CA)

1999-01-01T23:59:59.000Z

314

White light velocity interferometer  

DOE Patents [OSTI]

The invention is a technique that allows the use of broadband and incoherent illumination. Although denoted white light velocimetry, this principle can be applied to any wave phenomenon. For the first time, powerful, compact or inexpensive sources can be used for remote target velocimetry. These include flash and arc lamps, light from detonations, pulsed lasers, chirped frequency lasers, and lasers operating simultaneously in several wavelengths. The technique is demonstrated with white light from an incandescent source to measure a target moving at 16 m/s. 41 figs.

Erskine, D.J.

1999-06-08T23:59:59.000Z

315

GaAs/AlGaAs nanostructured composites for free-space and integrated optical devices  

E-Print Network [OSTI]

after development with MIBK:IPA=1:2 for 2min. Different fillon GaAs developed with MIBK:IPA=1:2 for (a) 1 min; (b) 2d) shows a nonoptimized developer, MIBK:IPA=2:1, used for 3

Tsai, Chia-Ho

2006-01-01T23:59:59.000Z

316

Lakeview Light and Power- Commercial Lighting Rebate Program  

Broader source: Energy.gov [DOE]

Lakeview Light and Power offers a commercial lighting rebate program. Rebates apply to the installation of energy efficient lighting retrofits in non-residential buildings. The rebate program is...

317

O?[]O? nuclear ?-decay of ?²Ga  

E-Print Network [OSTI]

information, MARS was focused such that only fully stripped N=Z ions were passed, with the vast majority of them being Ga. The second phase of the experiment was a I3-y coincidence experiment. At the back-end of MARS, a 1" x 1 '!4" x 3" four..., using the Weinberg-Salam model of electroweak interactions, to be [23]: A& ? d, ?= ? [41n(mz/m )+ln(m /m?)+2K+A +" ]. (16) Here mz is the mass of the Z boson, me the proton mass, mx is the low energy cutoff for the second and third terms that arise...

Hyman, Bruce Carl

1999-01-01T23:59:59.000Z

318

General Atomics (GA) | Princeton Plasma Physics Lab  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary)morphinanInformation Desert Southwest Region service area. TheEPSCIResearch to sponsorGeneral Atomics (GA)

319

GA SNC Solar | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of Inspector GeneralDepartmentAUDIT REPORTOpen EnergyBoard" form. To create aGA SNC Solar Jump to:

320

Light emission patterns from stadium-shaped semiconductor microcavity lasers  

E-Print Network [OSTI]

We study light emission patterns from stadium-shaped semiconductor (GaAs) microcavity lasers theoretically and experimentally. Performing systematic wave calculations for passive cavity modes, we demonstrate that the averaging by low-loss modes, such as those realized in multi-mode lasing, generates an emission pattern in good agreement with the ray model's prediction. In addition, we show that the dependence of experimental far-field emission patterns on the aspect ratio of the stadium cavity is well reproduced by the ray model.

Susumu Shinohara; Takehiro Fukushima; Takahisa Harayama

2008-03-10T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Theoretical studies of optical gain tuning by hydrostatic pressure in GaInNAs/GaAs quantum wells  

SciTech Connect (OSTI)

In order to describe theoretically the tuning of the optical gain by hydrostatic pressure in GaInNAs/GaAs quantum wells (QWs), the optical gain calculations within kp approach were developed and applied for N-containing and N-free QWs. The electronic band structure and the optical gain for GaInNAs/GaAs QW were calculated within the 10-band kp model which takes into account the interaction of electron levels in the QW with the nitrogen resonant level in GaInNAs. It has been shown that this interaction increases with the hydrostatic pressure and as a result the optical gain for GaInNAs/GaAs QW decreases by about 40% and 80% for transverse electric and transverse magnetic modes, respectively, for the hydrostatic pressure change from 0 to 40 kilobars. Such an effect is not observed for N-free QWs where the dispersion of electron and hole energies remains unchanged with the hydrostatic pressure. This is due to the fact that the conduction and valence band potentials in GaInAs/GaAs QW scale linearly with the hydrostatic pressure.

Gladysiewicz, M.; Wartak, M. S. [Institute of Physics, Wroclaw University of Technology, 50-370 Wroclaw, Wybrzeze Wyspianskiego 27 (Poland); Department of Physics and Computer Science, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 (Canada); Kudrawiec, R. [Institute of Physics, Wroclaw University of Technology, 50-370 Wroclaw, Wybrzeze Wyspianskiego 27 (Poland)

2014-01-21T23:59:59.000Z

322

Correlating electroluminescence characterization and physics-based models of InGaN/GaN LEDs: Pitfalls and open issues  

SciTech Connect (OSTI)

Electroluminescence (EL) characterization of InGaN/GaN light-emitting diodes (LEDs), coupled with numerical device models of different sophistication, is routinely adopted not only to establish correlations between device efficiency and structural features, but also to make inferences about the loss mechanisms responsible for LED efficiency droop at high driving currents. The limits of this investigative approach are discussed here in a case study based on a comprehensive set of current- and temperature-dependent EL data from blue LEDs with low and high densities of threading dislocations (TDs). First, the effects limiting the applicability of simpler (closed-form and/or one-dimensional) classes of models are addressed, like lateral current crowding, vertical carrier distribution nonuniformity, and interband transition broadening. Then, the major sources of uncertainty affecting state-of-the-art numerical device simulation are reviewed and discussed, including (i) the approximations in the transport description through the multi-quantum-well active region, (ii) the alternative valence band parametrizations proposed to calculate the spontaneous emission rate, (iii) the difficulties in defining the Auger coefficients due to inadequacies in the microscopic quantum well description and the possible presence of extra, non-Auger high-current-density recombination mechanisms and/or Auger-induced leakage. In the case of the present LED structures, the application of three-dimensional numerical-simulation-based analysis to the EL data leads to an explanation of efficiency droop in terms of TD-related and Auger-like nonradiative losses, with a C coefficient in the 10{sup ?30} cm{sup 6}/s range at room temperature, close to the larger theoretical calculations reported so far. However, a study of the combined effects of structural and model uncertainties suggests that the C values thus determined could be overestimated by about an order of magnitude. This preliminary attempt at uncertainty quantification confirms, beyond the present case, the need for an improved description of carrier transport and microscopic radiative and nonradiative recombination mechanisms in device-level LED numerical models.

Calciati, Marco; Vallone, Marco; Zhou, Xiangyu; Ghione, Giovanni [Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino (Italy); Goano, Michele, E-mail: michele.goano@polito.it; Bertazzi, Francesco [Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino (Italy); IEIIT-CNR, Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino (Italy); Meneghini, Matteo; Meneghesso, Gaudenzio; Zanoni, Enrico [Dipartimento di Ingegneria dell'Informazione, Università di Padova, Via Gradenigo 6/B, 35131 Padova (Italy); Bellotti, Enrico [Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, 02215 Boston, MA (United States); Verzellesi, Giovanni [Dipartimento di Scienze e Metodi dell'Ingegneria, Università di Modena e Reggio Emilia, 42122 Reggio Emilia (Italy); Zhu, Dandan; Humphreys, Colin [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

2014-06-15T23:59:59.000Z

323

Mesoscopic photovoltaic effect in GaAs/Ga1-xAlxAs Aharonov-Bohm rings L. Angers, A. Chepelianskii, R. Deblock, B. Reulet, and H. Bouchiat  

E-Print Network [OSTI]

Mesoscopic photovoltaic effect in GaAs/Ga1-xAlxAs Aharonov-Bohm rings L. Angers, A. Chepelianskii specific dc voltage. We have investigated this photovoltaic PV effect on GaAs/Ga1-xAlxAs Aharonov is generally done by measuring the dc induced signal sometimes called photovoltaic effect which has also given

Shepelyansky, Dima

324

Electrical spin injection into InGaAs/GaAs quantum wells: A comparison between MgO tunnel barriers grown by sputtering and molecular beam epitaxy methods  

SciTech Connect (OSTI)

An efficient electrical spin injection into an InGaAs/GaAs quantum well light emitting diode is demonstrated thanks to a CoFeB/MgO spin injector. The textured MgO tunnel barrier is fabricated by two different techniques: sputtering and molecular beam epitaxy. The maximal spin injection efficiency is comparable for both methods. Additionally, the effect of annealing is also investigated for the two types of samples. Both samples show the same trend: an increase of the electroluminescence circular polarization (P{sub c}) with the increase of annealing temperature, followed by a saturation of P{sub c} beyond 350?°C annealing. Since the increase of P{sub c} starts well below the crystallization temperature of the full CoFeB bulk layer, this trend could be mainly due to an improvement of chemical structure at the top CoFeB/MgO interface. This study reveals that the control of CoFeB/MgO interface is essential for an optimal spin injection into semiconductor.

Barate, P.; Zhang, T. T.; Vidal, M.; Renucci, P.; Marie, X.; Amand, T. [Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 avenue de Rangueil, 31077 Toulouse (France); Liang, S.; Devaux, X.; Hehn, M.; Mangin, S.; Lu, Y., E-mail: yuan.lu@univ-lorraine.fr [Institut Jean Lamour, UMR 7198, CNRS-Nancy Université, BP 239, 54506 Vandoeuvre (France); Frougier, J.; Jaffrès, H.; George, J. M. [Unité Mixte de Physique CNRS/Thales and Université Paris-Sud 11, 1 avenue A. Fresnel, 91767 Palaiseau (France); Xu, B.; Wang, Z. [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083 (China); Zheng, Y. [Institut des NanoSciences de Paris, UPMC, CNRS UMR 7588, 4 place Jussieu, 75005 Paris (France); Tao, B. [Institut Jean Lamour, UMR 7198, CNRS-Nancy Université, BP 239, 54506 Vandoeuvre (France); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190 (China); Han, X. F. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190 (China)

2014-07-07T23:59:59.000Z

325

Light Vector Mesons  

E-Print Network [OSTI]

This article reviews the current status of experimental results obtained in the measurement of light vector mesons produced in proton-proton and heavy ion collisions at different energies. The review is focused on two phenomena related to the light vector mesons; the modification of the spectral shape in search of Chiral symmetry restoration and suppression of the meson production in heavy ion collisions. The experimental results show that the spectral shape of light vector mesons are modified compared to the parameters measured in vacuum. The nature and the magnitude of the modification depends on the energy density of the media in which they are produced. The suppression patterns of light vector mesons are different from the measurements of other mesons and baryons. The mechanisms responsible for the suppression of the mesons are not yet understood. Systematic comparison of existing experimental results points to the missing data which may help to resolve the problem.

Alexander Milov

2008-12-21T23:59:59.000Z

326

National Synchrotron Light Source  

ScienceCinema (OSTI)

A tour of Brookhaven's National Synchrotron Light Source (NSLS). The NSLS is one of the world's most widely used scientific research facilities, hosting more than 2,500 guest researchers each year. The NSLS provides intense beams of infrared, ultraviole

None

2010-01-08T23:59:59.000Z

327

Efficient Light Sources Today  

E-Print Network [OSTI]

This paper reviews new lamp and lighting technology in terms of application and economic impact. Included are the latest advances in High Intensity Discharge systems, energy saving fluorescent lamps and ballasts, and the new state of the art high...

Hart, A. L.

1982-01-01T23:59:59.000Z

328

Natural lighting and skylights  

E-Print Network [OSTI]

outlined herein, the feasibility of using scale models for studying skylights is also an established fact. The method of analysis by models can be a valuable tool to any designer who is concerned about day-lighting....

Evans, Benjamin Hampton

1961-01-01T23:59:59.000Z

329

Reading Municipal Light Department- Business Lighting Rebate Program  

Broader source: Energy.gov [DOE]

Reading Municipal Light Department (RMLD) offers incentives for non-residential customers to install energy efficient lights and sensors in existing facilities. In addition to rebates for the...

330

Types of Lighting in Commercial Buildings - Lighting Characteristics  

Annual Energy Outlook 2013 [U.S. Energy Information Administration (EIA)]

of a light source's accuracy in rendering different colors when compared to a reference light source. The highest attainable CRI is 100. Lamps with CRIs above 70 are...

331

Columbia Water and Light- HVAC and Lighting Efficiency Rebates  

Broader source: Energy.gov [DOE]

Columbia Water and Light (CWL) offers rebates to its commercial and industrial customers for the purchase of high efficiency HVAC installations and efficient lighting. Incentives for certain...

332

Induction Lighting: An Old Lighting Technology Made New Again...  

Broader source: Energy.gov (indexed) [DOE]

around the same time that his rival, Thomas Edison, was working to improve the incandescent light bulb. In the early 1990s, several major lighting manufacturers introduced...

333

Peninsula Light Company- Commercial Efficient Lighting Rebate Program  

Broader source: Energy.gov [DOE]

Peninsula Light Company (PLC) offers a rebate program for commercial customers who wish to upgrade to energy efficient lighting. Participating customers must be served by PLC commercial service....

334

Development of a Bulk GaN Growth Technique for Low Defect Density...  

Broader source: Energy.gov (indexed) [DOE]

current due to bulk defects GaN is Grown Heteroepitaxially on Sapphire (and Silicon Carbide) Substrates * As grown GaN nucleation layers contain disordered GaN with many...

335

Reliability of AlGaN/GaN high electron mobility transistors on low dislocation density bulk GaN substrate: Implications of surface step edges  

SciTech Connect (OSTI)

To enable gaining insight into degradation mechanisms of AlGaN/GaN high electron mobility transistors, devices grown on a low-dislocation-density bulk-GaN substrate were studied. Gate leakage current and electroluminescence (EL) monitoring revealed a progressive appearance of EL spots during off-state stress which signify the generation of gate current leakage paths. Atomic force microscopy evidenced the formation of semiconductor surface pits at the failure location, which corresponds to the interaction region of the gate contact edge and the edges of surface steps.

Killat, N., E-mail: Nicole.Killat@bristol.ac.uk, E-mail: Martin.Kuball@bristol.ac.uk; Montes Bajo, M.; Kuball, M., E-mail: Nicole.Killat@bristol.ac.uk, E-mail: Martin.Kuball@bristol.ac.uk [Center for Device Thermography and Reliability (CDTR), H.H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Paskova, T. [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States) [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States); Materials Science and Engineering Department, North Carolina State University, Raleigh, North Carolina 27695 (United States); Evans, K. R. [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States)] [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States); Leach, J. [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States) [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States); Electrical and Computer Engineering Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Li, X.; Özgür, Ü.; Morkoç, H. [Electrical and Computer Engineering Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)] [Electrical and Computer Engineering Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Chabak, K. D.; Crespo, A.; Gillespie, J. K.; Fitch, R.; Kossler, M.; Walker, D. E.; Trejo, M.; Via, G. D.; Blevins, J. D. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States)] [Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States)

2013-11-04T23:59:59.000Z

336

Solid state lighting component  

DOE Patents [OSTI]

An LED component comprising an array of LED chips mounted on a planar surface of a submount with the LED chips capable of emitting light in response to an electrical signal. The LED chips comprise respective groups emitting at different colors of light, with each of the groups interconnected in a series circuit. A lens is included over the LED chips. Other embodiments can comprise thermal spreading structures included integral to the submount and arranged to dissipate heat from the LED chips.

Yuan, Thomas; Keller, Bernd; Ibbetson, James; Tarsa, Eric; Negley, Gerald

2010-10-26T23:59:59.000Z

337

Solid state lighting component  

DOE Patents [OSTI]

An LED component comprising an array of LED chips mounted on a planar surface of a submount with the LED chips capable of emitting light in response to an electrical signal. The LED chips comprise respective groups emitting at different colors of light, with each of the groups interconnected in a series circuit. A lens is included over the LED chips. Other embodiments can comprise thermal spreading structures included integral to the submount and arranged to dissipate heat from the LED chips.

Keller, Bernd; Ibbetson, James; Tarsa, Eric; Negley, Gerald; Yuan, Thomas

2012-07-10T23:59:59.000Z

338

High-Efficiency Nitride-Based Solid-State Lighting  

SciTech Connect (OSTI)

In this final technical progress report we summarize research accomplished during Department of Energy contract DE-FC26-01NT41203, entitled ''High-Efficiency Nitride-Based Solid-State Lighting''. Two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and the Lighting Research Center at Rensselaer Polytechnic Institute (led by Dr. N. Narendran), pursued the goals of this contract from thin film growth, characterization, and packaging/luminaire design standpoints. The UCSB team initially pursued the development of blue gallium nitride (GaN)-based vertical-cavity surface-emitting lasers, as well as ultraviolet GaN-based light emitting diodes (LEDs). In Year 2, the emphasis shifted to resonant-cavity light emitting diodes, also known as micro-cavity LEDs when extremely thin device cavities are fabricated. These devices have very directional emission and higher light extraction efficiency than conventional LEDs. Via the optimization of thin-film growth and refinement of device processing, we decreased the total cavity thickness to less than 1 {micro}m, such that micro-cavity effects were clearly observed and a light extraction efficiency of over 10% was reached. We also began the development of photonic crystals for increased light extraction, in particular for so-called ''guided modes'' which would otherwise propagate laterally in the device and be re-absorbed. Finally, we pursued the growth of smooth, high-quality nonpolar a-plane and m-plane GaN films, as well as blue light emitting diodes on these novel films. Initial nonpolar LEDs showed the expected behavior of negligible peak wavelength shift with increasing drive current. M-plane LEDs in particular show promise, as unpackaged devices had unsaturated optical output power of {approx} 3 mW at 200 mA drive current. The LRC's tasks were aimed at developing the subcomponents necessary for packaging UCSB's light emitting diodes, and packaging them to produce a white light fixture. During the third and final year of the project, the LRC team investigated alternate packaging methods for the white LED device to achieve at least 25 percent more luminous efficacy than traditional white LEDs; conducted optical ray-tracing analyses and human factors studies to determine the best form factor for the white light source under development, in terms of high luminous efficacy and greater acceptance by subjects; and developed a new die encapsulant using silicone-epoxy resins that showed less yellowing and slower degradation. At the conclusion of this project, the LRC demonstrated a new packaging method, called scattered photon extraction (SPE), that produced an average luminous flux and corresponding average efficacy of 90.7 lm and 36.3 lm/W, respectively, compared with 56.5 lm and 22.6 lm/W for a similar commercial white LED package. At low currents, the SPE package emitted white light with an efficacy of over 80 lm/W and had chromaticity values very close to the blackbody locus. The SPE package showed an overall improvement of 61% for this particular comparison, exceeding the LRC's third-year goal of 25% improvement.

Paul T. Fini; Shuji Nakamura

2005-07-30T23:59:59.000Z

339

Light and Energy -Daylight measurements  

E-Print Network [OSTI]

Light and Energy - Daylight measurements #12;Light and Energy - Daylight measurements Authors: Jens;3 Title Light and Energy Subtitle Daylight measurements Authors Jens Christoffersen, Ásta Logadóttir ........................................................................................................ 5 Daylight quantity

340

Energy Conservation in Industrial Lighting  

E-Print Network [OSTI]

In order to reduce energy use in lighting Union Carbide recently issued drastically reduced new lighting level standards. A computerized lighting cost program was also developed. Using this program a number of additional energy saving techniques...

Meharg, E.

1979-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Lighting and the Bottom Line  

E-Print Network [OSTI]

A discussion of the cost of light and how it relates to the cost of people. The new Illuminating Engineering Society recommended method of determining lighting levels will be explained. Also several ways of providing good lighting to increase...

Christensen, M.

1981-01-01T23:59:59.000Z

342

Light diffusing fiber optic chamber  

DOE Patents [OSTI]

A light diffusion system for transmitting light to a target area. The light is transmitted in a direction from a proximal end to a distal end by an optical fiber. A diffusing chamber is operatively connected to the optical fiber for transmitting the light from the proximal end to the distal end and transmitting said light to said target area. A plug is operatively connected to the diffusing chamber for increasing the light that is transmitted to the target area.

Maitland, Duncan J. (Lafayette, CA)

2002-01-01T23:59:59.000Z

343

The Essentials for GA Water Planning The Relationship  

E-Print Network [OSTI]

" FL Water Law Regulated Riparianism "Heavy" Admin Water Law ? #12;Comprehensive Water Resource Study Supply a. Water Allocation ­ Withdrawal Permit Program b. Water Storage & Delivery c. Interbasin TransferThe Essentials for GA Water Planning The Relationship Between the Proposed GA State Comprehensive

Rosemond, Amy Daum

344

CoNiGa High Temperature Shape Memory Alloys  

E-Print Network [OSTI]

commercially successful SMAs such as NiTi and Cu-based alloys. In recent years, the CoNiGa system has emerged as a new ferromagnetic shape memory alloy with some compositions exhibiting high martensitic transformation temperatures which makes CoNiGa a potential...

Dogan, Ebubekir

2011-10-21T23:59:59.000Z

345

Temperature-induced martensite in magnetic shape memory Fe{sub 2}MnGa observed by photoemission electron microscopy  

SciTech Connect (OSTI)

The magnetic domain structure in single crystals of a Heusler shape memory compound near the composition Fe{sub 2}MnGa was observed during phase transition by photoelectron emission microscopy at Beamline 11.0.1.1 of the Advanced Light Source. The behavior is comparable with recent observations of an adaptive martensite phase in prototype Ni{sub 2}MnGa, although the pinning in the recent work is an epitaxial interface and in this work the e#11;ective pinning plane is a boundary between martensitic variants that transform in a self-accommodating way from the single crystal austenite phase present at high temperatures. Temperature dependent observations of the twinning structure give information as to the coupling behavior between the magnetism and the structural evolution.

Jenkins, Catherine; Scholl, Andreas; Kainuma, R.; Elmers, Hans-Joachim; Omori, Toshihiro

2012-01-18T23:59:59.000Z

346

July 18, 2012 Using QECBs for Street Lighting Upgrades  

E-Print Network [OSTI]

lighting technologies (e.g. light-emitting diodes, induction lighting) can reduce street light energy

347

Efficiency Maine Residential Lighting Program  

Broader source: Energy.gov [DOE]

Efficiency Maine's Residential Lighting Program works directly with retailers and manufacturers to encourage residential customers to purchase energy-efficient lighting. Rebate amounts average $1...

348

Partially filled intermediate band of Cr-doped GaN films  

SciTech Connect (OSTI)

We investigated the band structure of sputtered Cr-doped GaN (GaCrN) films using optical absorption, photoelectron yield spectroscopy, and charge transport measurements. It was found that an additional energy band is formed in the intrinsic band gap of GaN upon Cr doping, and that charge carriers in the material move in the inserted band. Prototype solar cells showed enhanced short circuit current and open circuit voltage in the n-GaN/GaCrN/p-GaN structure compared to the GaCrN/p-GaN structure, which validates the proposed concept of an intermediate-band solar cell.

Sonoda, S. [Department of Electronics, Kyoto Institute of Technology, Kyoto 606-8585 (Japan)

2012-05-14T23:59:59.000Z

349

Elastic properties of Pu metal and Pu-Ga alloys  

SciTech Connect (OSTI)

We present elastic properties, theoretical and experimental, of Pu metal and Pu-Ga ({delta}) alloys together with ab initio equilibrium equation-of-state for these systems. For the theoretical treatment we employ density-functional theory in conjunction with spin-orbit coupling and orbital polarization for the metal and coherent-potential approximation for the alloys. Pu and Pu-Ga alloys are also investigated experimentally using resonant ultrasound spectroscopy. We show that orbital correlations become more important proceeding from {alpha} {yields} {beta} {yields} {gamma} plutonium, thus suggesting increasing f-electron correlation (localization). For the {delta}-Pu-Ga alloys we find a softening with larger Ga content, i.e., atomic volume, bulk modulus, and elastic constants, suggest a weakened chemical bonding with addition of Ga. Our measurements confirm qualitatively the theory but uncertainties remain when comparing the model with experiments.

Soderlind, P; Landa, A; Klepeis, J E; Suzuki, Y; Migliori, A

2010-01-05T23:59:59.000Z

350

A wide-bandwidth low-noise InGaAsP-InAlAs superlattice avalanche photodiode with a flip-chip structure for wavelengths of 1. 3 and 1. 55 [mu]m  

SciTech Connect (OSTI)

This paper reports the fabrication of a flip-chip InGaAsP-InAlAs superlattice avalanche photodiode using gas source molecular beam epitaxy. The incident light reaches the InGaAs photoabsorption layer through the InP substrate and an InGaAsP-InAlAs superlattice multiplication region which are transparent for wavelengths of 1.55 and 1.3 [mu]m. The light reflection by the electrode enables the absorption layer to be as thin as 0.8 [mu]m without significantly reducing the quantum efficiency. A maximum bandwidth of 17 GHz was obtained at a low multiplication factor because of the transit time through the absorption layer is reduced.

Kagawa, Toshiaki; Kawamura, Yuichi; Iwamura, Hidetoshi (NTT Opto-electronics Labs., Atsugi-shi, Kanagawa (Japan))

1993-05-01T23:59:59.000Z

351

Output Harmonic Termination Techniques for AlGaN/GaN HEMT Power Amplifiers Using Active Integrated Antenna Approach  

E-Print Network [OSTI]

Output Harmonic Termination Techniques for AlGaN/GaN HEMT Power Amplifiers Using Active Integrated 1200, Los Angeles, CA 90045 Abstract -- In this paper, effects of output harmonic terminations on PAE termination, we observe a substantial increase in PAE and output power. Further, we demonstrate the high

Itoh, Tatsuo

352

AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors using barium strontium titanate  

E-Print Network [OSTI]

AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors using barium strontium-effect transistors have been formed by incorporating barium strontium titanate (BST) deposited by rf magnetron in increased leakage. Due to its large dielectric constant, barium strontium ti- tanate [Ba1-xSrxTiO3, (BST

York, Robert A.

353

Mn-doped Ga(As,P) and (Al,Ga)As ferromagnetic semiconductors: Electronic structure calculations  

E-Print Network [OSTI]

A remarkable progress towards functional ferromagnetic semiconductor materials for spintronics has been achieved in p-type (Ga,Mn)As. Robust hole-mediated ferromagnetism has, however, been observed also in other III-V hosts such as antimonides, Ga...

Masek, J.; Kudrnovsky, J.; Maca, F.; Sinova, Jairo; MacDonald, A. H.; Campion, R. P.; Gallagher, B. L.; Jungwirth, T.

2007-01-01T23:59:59.000Z

354

High-Performance Integrated Dual-Gate AlGaN/GaN Enhancement-Mode Transistor  

E-Print Network [OSTI]

In this letter, we present a new AlGaN/GaN enhancement-mode (E-mode) transistor based on a dual-gate structure. The dual gate allows the transistor to combine an E-mode behavior with low on-resistance and very high breakdown ...

Lu, Bin

355

Fabrication of quantum point contacts by engraving GaAsAlGaAs heterostructures with a diamond tip  

E-Print Network [OSTI]

by hot-filament chemical vapor deposition of polycrystalline diamond onto a prepat- terned siliconFabrication of quantum point contacts by engraving GaAsÕAlGaAs heterostructures with a diamond tip for publication 17 July 2002 We use the all-diamond tip of an atomic force microscope for the direct engraving

Hohls, Frank

356

OPTIMIZATION OF GaN WINDOW LAYER FOR InGaN SOLAR CELLS USING POLARIZATION EFFECT  

E-Print Network [OSTI]

on the design of wide-band gap GaN window layers for InGaN solar cells. Window layers serve to passivate the top into account during design of the solar cell to improve its collection efficiency. Previously, we have. The present work is a subset of the design optimization process for such solar cells, where we focus

Honsberg, Christiana

357

Si-CMOS-Like Integration of AlGaN/GaN Dielectric-Gated High-Electron-Mobility Transistors  

E-Print Network [OSTI]

the engineering of high mobility, high carrier density channels at III-Nitride heterointerfaces. In order to seize market share from silicon, the cost of manufacturing GaN-based devices must be further reduced. With the successful realization of 200mm Ga...

Johnson, Derek Wade

2014-07-31T23:59:59.000Z

358

Analysis of the reduced thermal conductivity in InGaAs/GaAs quantum dot lasers from chirp characteristics  

E-Print Network [OSTI]

injection which we term "thermal impact" , the ther- mal conductivity of the active region is estimatedAnalysis of the reduced thermal conductivity in InGaAs/GaAs quantum dot lasers from chirp; published online 21 September 2006 The thermal conductivity of self-organized quantum dot QD active regions

Klotzkin, David

359

Diffusion of a Ga adatom on the GaAs(001)c(44)heterodimer surface: A first principles study  

E-Print Network [OSTI]

Diffusion of a Ga adatom on the GaAs(001)c(4×4)heterodimer surface: A first principles study J Diffusion barriers Reconstruction Density functional calculations The adsorption and diffusion behavior functional theory (DFT) computations in the local density approxima- tion. Structural and bonding features

Khare, Sanjay V.

360

Electric field dependent radiative decay kinetics of polar InGaN/GaN quantum heterostructures at low fields  

E-Print Network [OSTI]

Electric field dependent radiative decay kinetics of polar InGaN/GaN quantum heterostructures with increasing external electric field, with the radiative component exhibiting weaker field dependence. © 2009 applied electric field in Ref. 12, the electric field dependent radiative recombination in particular has

Demir, Hilmi Volkan

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Optical study of hydrogen-irradiated GaAsN/GaAs heterostructures M. Geddo,1,a)  

E-Print Network [OSTI]

Optical study of hydrogen-irradiated GaAsN/GaAs heterostructures M. Geddo,1,a) M. Patrini,1 G; accepted 5 May 2011; published online 20 June 2011) The effect of hydrogen irradiation on the optical for fiber optic communications. These promising results in view of the development of waveguides deserve

362

An AlGaAsGaAs quantum cascade laser operating with a thermoelectric cooler for spectroscopy of NH3  

E-Print Network [OSTI]

out using a compact thermo-electrically cooled laser package. The QCL described here is designedAn AlGaAs­GaAs quantum cascade laser operating with a thermoelectric cooler for spectroscopy of NH3. Langford b a Department of Electronics and Electrical Engineering, Rankine Building, University of Glasgow

363

Infrared reflection of GaN and AlGaN thin film heterostructures with AlN buffer layers  

E-Print Network [OSTI]

Infrared reflection of GaN and AlGaN thin film heterostructures with AlN buffer layers C. Wetzel, Nagoya, Japan Received 11 December 1995; accepted for publication 21 February 1996 Infrared reflection, their alloys and potential substrates need to be investigated as well. Here we present a study of the infrared

Wetzel, Christian M.

364

Lighting affects appearance LightSource emits photons  

E-Print Network [OSTI]

1 Lighting affects appearance #12;2 LightSource emits photons Photons travel in a straight line). And then some reach the eye/camera. #12;3 Basic fact: Light is linear Double intensity of sources, double photons reaching eye. Turn on two lights, and photons reaching eye are same as sum of number when each

Jacobs, David

365

ECE 466: LED Lighting Systems -Incandescent lightings rise and  

E-Print Network [OSTI]

versus cost - Power Electronic Drives for CFL and LED light sources to achieve dimmable operation - Basic electric AC and DC circuits at Sophomore level or equivalents Absolutes Lighting System Requirements index as a metric of a light source - Power Electronic Energy sources driving light sources in a compact

Schumacher, Russ

366

Lighting and Surfaces 11.1 Introduction to Lighting  

E-Print Network [OSTI]

-object-at-a-time. "Intrinsic" light is the light emitted by the object itself, such as the glow from a TV screen, a light-emitting diode, or a star. "Ambient" light is an illumination that seems to come from all sides. In the real

Boyd, John P.

367

Sandia National Laboratories: White Light Creation Architectures  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

TechnologiesWhite Light Creation Architectures White Light Creation Architectures Overview of SSL White Light Creation Architectures The entire spectral range of visible light can...

368

Advanced Epi Tools for Gallium Nitride Light Emitting Diode Devices  

SciTech Connect (OSTI)

Over the course of this program, Applied Materials, Inc., with generous support from the United States Department of Energy, developed a world-class three chamber III-Nitride epi cluster tool for low-cost, high volume GaN growth for the solid state lighting industry. One of the major achievements of the program was to design, build, and demonstrate the world’s largest wafer capacity HVPE chamber suitable for repeatable high volume III-Nitride template and device manufacturing. Applied Materials’ experience in developing deposition chambers for the silicon chip industry over many decades resulted in many orders of magnitude reductions in the price of transistors. That experience and understanding was used in developing this GaN epi deposition tool. The multi-chamber approach, which continues to be unique in the ability of the each chamber to deposit a section of the full device structure, unlike other cluster tools, allows for extreme flexibility in the manufacturing process. This robust architecture is suitable for not just the LED industry, but GaN power devices as well, both horizontal and vertical designs. The new HVPE technology developed allows GaN to be grown at a rate unheard of with MOCVD, up to 20x the typical MOCVD rates of 3{micro}m per hour, with bulk crystal quality better than the highest-quality commercial GaN films grown by MOCVD at a much cheaper overall cost. This is a unique development as the HVPE process has been known for decades, but never successfully commercially developed for high volume manufacturing. This research shows the potential of the first commercial-grade HVPE chamber, an elusive goal for III-V researchers and those wanting to capitalize on the promise of HVPE. Additionally, in the course of this program, Applied Materials built two MOCVD chambers, in addition to the HVPE chamber, and a robot that moves wafers between them. The MOCVD chambers demonstrated industry-leading wavelength yield for GaN based LED wafers and industry-leading uptime enabled in part by a novel in-situ cleaning process developed in this program.

Patibandla, Nag; Agrawal, Vivek

2012-12-01T23:59:59.000Z

369

Single photon emission from site-controlled InGaN/GaN quantum dots  

SciTech Connect (OSTI)

Single photon emission was observed from site-controlled InGaN/GaN quantum dots. The single-photon nature of the emission was verified by the second-order correlation function up to 90?K, the highest temperature to date for site-controlled quantum dots. Micro-photoluminescence study on individual quantum dots showed linearly polarized single exciton emission with a lifetime of a few nanoseconds. The dimensions of these quantum dots were well controlled to the precision of state-of-the-art fabrication technologies, as reflected in the uniformity of their optical properties. The yield of optically active quantum dots was greater than 90%, among which 13%–25% exhibited single photon emission at 10?K.

Zhang, Lei; Hill, Tyler A.; Deng, Hui, E-mail: dengh@umich.edu [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109 (United States)] [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109 (United States); Teng, Chu-Hsiang; Lee, Leung-Kway; Ku, Pei-Cheng, E-mail: peicheng@umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109 (United States)] [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109 (United States)

2013-11-04T23:59:59.000Z

370

Large linear magnetoresistance in a GaAs/AlGaAs heterostructure  

SciTech Connect (OSTI)

We report non-saturating linear magnetoresistance (MR) in a two-dimensional electron system (2DES) at a GaAs/AlGaAs heterointerface in the strongly insulating regime. We achieve this by driving the gate voltage below the pinch-off point of the device and operating it in the non-equilibrium regime with high source-drain bias. Remarkably, the magnitude of MR is as large as 500% per Tesla with respect to resistance at zero magnetic field, thus dwarfing most non-magnetic materials which exhibit this linearity. Its primary advantage over most other materials is that both linearity and the enormous magnitude are retained over a broad temperature range (0.3 K to 10 K), thus making it an attractive candidate for cryogenic sensor applications.

Aamir, Mohammed Ali, E-mail: aamir@physics.iisc.ernet.in; Goswami, Srijit, E-mail: aamir@physics.iisc.ernet.in; Ghosh, Arindam [Department of Physics, Indian Institute of Science, Bangalore 560 012 (India); Baenninger, Matthias; Farrer, Ian; Ritchie, David A. [Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Tripathi, Vikram [Department of Theoretical Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Pepper, Michael [Department of Electrical and Electronic Engineering, University College, London WC1E 7JE (United Kingdom)

2013-12-04T23:59:59.000Z

371

Enhanced optical property in quaternary GaInAsSb/AlGaAsSb quantum wells  

SciTech Connect (OSTI)

High quality GaInAsSb/AlGaAsSb quantum wells (QWs) have been grown by molecular beam epitaxy using proper interface treatments. By controlling the group-V elements at interfaces, we obtained excellent optical quality QWs, which were free from undesired localized trap states, which may otherwise severely affect the exciton recombination. Strong and highly efficient exciton emissions up to room temperature with a wavelength of 2.2 ?m were observed. A comprehensive investigation on the QW quality was carried out using temperature dependent and power dependent photoluminescence (PL) measurements. The PL emission intensity remains nearly constant at low temperatures and is free from the PL quenching from the defect induced localized states. The temperature dependent emission energy had a bulk-like behavior, indicating high quality well/barrier interfaces. Because of the uniformity of the QWs and smooth interfaces, the low temperature limit of inhomogeneous line width broadening is as small as 5?meV.

Lin, Chien-Hung, E-mail: chlin.ee97g@g2.nctu.edu.tw; Lee, Chien-Ping [Department of Electronics Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan (China)

2014-10-21T23:59:59.000Z

372

Pupillary efficient lighting system  

DOE Patents [OSTI]

A lighting system having at least two independent lighting subsystems each with a different ratio of scotopic illumination to photopic illumination. The radiant energy in the visible region of the spectrum of the lighting subsystems can be adjusted relative to each other so that the total scotopic illumination of the combined system and the total photopic illumination of the combined system can be varied independently. The dilation or contraction of the pupil of an eye is controlled by the level of scotopic illumination and because the scotopic and photopic illumination can be separately controlled, the system allows the pupil size to be varied independently of the level of photopic illumination. Hence, the vision process can be improved for a given level of photopic illumination.

Berman, Samuel M. (San Francisco, CA); Jewett, Don L. (Mill Valley, CA)

1991-01-01T23:59:59.000Z

373

Light harvesting arrays  

DOE Patents [OSTI]

A light harvesting array useful for the manufacture of devices such as solar cells comprises: (a) a first substrate comprising a first electrode; and (b) a layer of light harvesting rods electrically coupled to the first electrode, each of the light harvesting rods comprising a polymer of Formula I: X.sup.1.paren open-st.X.sup.m+1).sub.m (I) wherein m is at least 1, and may be from two, three or four to 20 or more; X.sup.1 is a charge separation group (and preferably a porphyrinic macrocycle, which may be one ligand of a double-decker sandwich compound) having an excited-state of energy equal to or lower than that of X.sup.2, and X.sup.2 through X.sup.m+1 are chromophores (and again are preferably porphyrinic macrocycles).

Lindsey, Jonathan S. (Raleigh, NC)

2002-01-01T23:59:59.000Z

374

Light emitting ceramic device  

DOE Patents [OSTI]

A light-emitting ceramic based panel, hereafter termed "electroceramescent" panel, is herein claimed. The electroceramescent panel is formed on a substrate providing mechanical support as well as serving as the base electrode for the device. One or more semiconductive ceramic layers directly overlay the substrate, and electrical conductivity and ionic diffusion are controlled. Light emitting regions overlay the semiconductive ceramic layers, and said regions consist sequentially of a layer of a ceramic insulation layer and an electroluminescent layer, comprised of doped phosphors or the equivalent. One or more conductive top electrode layers having optically transmissive areas overlay the light emitting regions, and a multi-layered top barrier cover comprising one or more optically transmissive non-combustible insulation layers overlay said top electrode regions.

Valentine, Paul; Edwards, Doreen D.; Walker, Jr., William John; Slack, Lyle H.; Brown, Wayne Douglas; Osborne, Cathy; Norton, Michael; Begley, Richard

2010-05-18T23:59:59.000Z

375

Strain relaxation effect by nanotexturing InGaN/GaN multiple quantum well  

SciTech Connect (OSTI)

The relaxation of lattice-mismatched strain by deep postetching was systematically investigated for InGaN/GaN multiple quantum wells (MQWs). A planar heterojunction wafer, which included an In{sub 0.21}Ga{sub 0.79}N (3.2 nm)/GaN (14.8 nm) MQW, was etched by inductively coupled plasma dry etching, to fabricate high-density nanopillar, nanostripe, and nanohole arrays. The etching depth was 570 nm for all nanostructures. The diameter of the nanopillars was varied from 50 to 300 nm, then the mesa stripe width of the nanostripes and the diameter of the nanoholes were varied from 100 nm to 440 nm and 50 nm to 310 nm, respectively. The effect of strain relaxation on various optical properties was investigated. For example, in an array of nanopillars with diameter 130 nm and interval 250 nm, a large blueshift in the photoluminescence (PL) emission peak from 510 nm (as-grown) to 459 nm occurred at room temperature (RT). PL internal quantum efficiency (defined by the ratio of PL integral intensity at 300 K to that at 4.2 K) was enhanced from 34% (as-grown) to 60%, and the PL decay time at 4.2 K was reduced from 22 ns (as-grown) to 4.2 ns. These results clearly indicate the reduction of lattice-mismatched strain by postetching, which enhanced strain reduction with decreasing nanopillar diameter down to a diameter of 130 nm, where the strain reduction became saturated. The dependence of RT-PL decay time on nanopillar diameter was measured, and the surface nonradiative recombination velocity was estimated to be 5.8x10{sup 2} cm/s. This relatively slow rate indicates a little etching damage.

Ramesh, V.; Kikuchi, A.; Kishino, K. [Department of Electrical and Electronics Engineering, Sophia University, Tokyo 102-8554, Japan and Nano-technology Research Center, Sophia University, Tokyo 102-8554 (Japan); CREST, JST, Saitama 332-0012 (Japan); Funato, M.; Kawakami, Y. [CREST, JST, Saitama 332-0012 (Japan); Department of Electronics Science and Engineering, Kyoto University, Kyoto 615-8510 (Japan)

2010-06-15T23:59:59.000Z

376

Radioluminescent lighting technology  

SciTech Connect (OSTI)

The glow-in-the-dark stereotype that characterizes the popular image of nuclear materials is not accidental. When the French scientist, Henri Becquerel, first discovered radioactivity in 1896, he was interested in luminescence. Radioluminescence, the production of light from a mixture of energetic and passive materials, is probably the oldest practical application of the unstable nucleus. Tritium-based radioluminescent lighting, in spite of the biologically favorable character of the gaseous tritium isotope, was included in the general tightening of environmental and safety regulations. Tritium light manufacturers would have to meet two fundamental conditions: (1) The benefit clearly outweighed the risk, to the extent that even the perceived risk of a skeptical public would be overcome. (2) The need was significant enough that the customer/user would be willing and able to afford the cost of regulation that was imposed both in the manufacture, use and eventual disposal of nuclear materials. In 1981, researchers at Oak Ridge National Laboratory were investigating larger radioluminescent applications using byproduct nuclear material such as krypton-85, as well as tritium. By 1982, it appeared that large source, (100 Curies or more) tritium gas tube, lights might be useful for marking runways and drop zones for military operations and perhaps even special civilian aviation applications. The successful development of this idea depended on making the light bright enough and demonstrating that large gas tube sources could be used and maintained safely in the environment. This successful DOE program is now in the process of being completed and closed-out. Working closely with the tritium light industry, State governments and other Federal agencies, the basic program goals have been achieved. This is a detailed report of what they have learned, proven, and discovered. 91 refs., 29 figs., 5 tabs. (JF)

Not Available

1990-01-01T23:59:59.000Z

377

MANDATORY MEASURES INDOOR LIGHTING CONTROLS  

E-Print Network [OSTI]

MANDATORY MEASURES INDOOR LIGHTING CONTROLS (Reference: Sub-Chapter 4, Section 130.1) #12;SECTION 4 MANDATORY LIGHTING CONTROLS 1. 130.1 (a) Area Controls: Manual controls that control lighting in each area separately 2. 130.1 (b) Multi-level Controls: Allow occupants to choose the appropriate light level for each

California at Davis, University of

378

MANDATORY MEASURES INDOOR LIGHTING CONTROLS  

E-Print Network [OSTI]

MANDATORY MEASURES INDOOR LIGHTING CONTROLS (Reference: Sub-Chapter 4, Section 130.1) #12;SECTION 3 MANDATORY LIGHTING CONTROLS 1. 130.1 (a) Area Controls: Manual controls that control lighting in each area separately 2. 130.1 (b) Multi-level Controls: "Dimmability." Allow occupants to choose the appropriate light

California at Davis, University of

379

LIGHTING 101 1. Common terminology  

E-Print Network [OSTI]

SECTION 3 LIGHTING 101 1. Common terminology 2. Sources & luminaires 3. Controls #12;SECTION 3SECTION 3 DISCUSSION: COMMON LIGHTING TERMINOLOGY 1. What are the definitions of the following lighting terms? 2. Do you use these terms in professional practice? 3. What other lighting terminology do you use

California at Davis, University of

380

MANDATORY MEASURES INDOOR LIGHTING CONTROLS  

E-Print Network [OSTI]

MANDATORY MEASURES INDOOR LIGHTING CONTROLS (Reference: Sub-Chapter 4, Section 130.1) #12;SECTION 5 MANDATORY LIGHTING CONTROLS 1. Area Controls: Manual controls that control lighting in each area separately 2. Multi-level Controls: Allow occupants to choose the appropriate light level for each area 3. Shut

California at Davis, University of

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

LIGHTING 101 1. Common terminology  

E-Print Network [OSTI]

LIGHTING 101 1. Common terminology 2. Sources and luminaires 3. Controls #12;SECTION 2 DISCUSSION: COMMON LIGHTING TERMINOLOGY 1. What are the definitions of the following lighting terms? 2. Do you use these terms in professional practice? 3. What other lighting terminology do you use on the job? SLIDE 14

California at Davis, University of

382

Extreme Ultraviolet Light Chris Cosio  

E-Print Network [OSTI]

Prospectus Extreme Ultraviolet Light Chris Cosio #12;The field of extreme ultraviolet light (XUV to the way XUV interacts with object, XUV properties are difficult to observe. Extreme ultraviolet light is absorbed by all objects it comes in contact with. Furthermore, extreme ultraviolet light also has low

Hart, Gus

383

Windows and lighting program  

SciTech Connect (OSTI)

More than 30% of all energy use in buildings is attributable to two sources: windows and lighting. Together they account for annual consumer energy expenditures of more than $50 billion. Each affects not only energy use by other major building systems, but also comfort and productivity -- factors that influence building economics far more than does direct energy consumption alone. Windows play a unique role in the building envelope, physically separating the conditioned space from the world outside without sacrificing vital visual contact. Throughout the indoor environment, lighting systems facilitate a variety of tasks associated with a wide range of visual requirements while defining the luminous qualities of the indoor environment. Windows and lighting are thus essential components of any comprehensive building science program. Despite important achievements in reducing building energy consumption over the past decade, significant additional savings are still possible. These will come from two complementary strategies: (1) improve building designs so that they effectively apply existing technologies and extend the market penetration of these technologies; and (2) develop advanced technologies that increase the savings potential of each application. Both the Windows and Daylighting Group and the Lighting System Research Group have made substantial contributions in each of these areas, and continue to do so through the ongoing research summarized here. 23 refs., 16 figs.

Not Available

1990-06-01T23:59:59.000Z

384

Radioluminescent polymer lights  

SciTech Connect (OSTI)

The preparation of radioluminescent light sources where the tritium is located on the aryl-ring in a polymer has been demonstrated with deuterium/tritium substitution. This report discusses tests, results, and future applications of radioluminescent polymers. 10 refs. (FI)

Jensen, G.A.; Nelson, D.A.; Molton, P.M.

1990-09-01T23:59:59.000Z

385

Sweetness and light   

E-Print Network [OSTI]

1. Sweetness and Light. A novel. Judi lives in a nice, clean house with her seventeen year old stepson, who won’t talk to her in anything but monosyllables. His father, Nelson, and she are struggling to relate to each ...

Craig, Katie

2014-07-03T23:59:59.000Z

386

Field dependent emission rates in radiation damaged GaAs  

SciTech Connect (OSTI)

We have measured the temperature and field dependence of emission rates from five traps in electron damaged GaAs. Four of the traps have previously been identified as radiation defects. One of the traps, seen in higher doped diodes, has not been previously identified. We have fit the data to a multiphonon emission theory that allows recombination in GaAs to be characterized over a broad range of temperature and electric field. These results demonstrate an efficient method to calculate field-dependent emission rates in GaAs.

Fleming, R. M.; Myers, S. M.; Wampler, W. R.; Lang, D. V.; Seager, C. H.; Campbell, J. M. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1415 (United States)

2014-07-07T23:59:59.000Z

387

Pulsed Electrical Spin Injection into InGaAs Quantum Dots: Studies of the Electroluminescence Polarization Dynamics  

SciTech Connect (OSTI)

We present time-resolved studies of the spin polarization dynamics during and after initialization through pulsed electrical spin injection into InGaAs quantum dots embedded in a p-i-n-type spin-injection light-emitting diode. Experiments are performed with pulse widths in the nanosecond range and a time-resolved single photon counting setup is used to detect the subsequent electroluminescence. We find evidence that the achieved spin polarization shows an unexpected temporal behavior, attributed mainly to many-carrier and non-equilibrium effects in the device.

Asshoff, P.; Loeffler, W.; Fluegge, H.; Zimmer, J.; Mueller, J.; Westenfelder, B.; Hu, D. Z.; Schaadt, D. M.; Kalt, H.; Hetterich, M. [Institut fuer Angewandte Physik and DFG Center for Functional Nanostructures (CFN), Universitaet Karlsruhe, 76131 Karlsruhe (Germany)

2010-01-04T23:59:59.000Z

388

Highly polarized emission in spin resolved photoelectron spectroscopy of alpha-Fe(001)/GaAs(001)  

SciTech Connect (OSTI)

Highly spin-polarized sources of electrons, Integrated into device design, remain of great interest to the spintronic and magneto-electronic device community Here, the growth of Fe upon GaAs(001) has been studied with photoelectron spectroscopy (PES), including Spin Resolved PES. Despite evidence of atomic level disorder such as intermixing, an over-layer with the spectroscopic signature of alpha-Fe(001), with a bcc real space ordering, Is obtained The results will be discussed in light of the possibility of using such films as a spin-polarized source in device applications.

Tobin, James; Yu, Sung Woo; Morton, Simon; Waddill, George; Thompson, Jamie; Neal, James; Spangenberg, Matthais; Shen, T.H.

2009-05-19T23:59:59.000Z

389

Effect of Sb on the Properties of GaInP Top Cells (Presentation)  

SciTech Connect (OSTI)

The summary of this report is that: (1) Sb can be used to increase V{sub oc} of a GaInP top cell; (2) the photovoltaic quality of GaInP is relatively unaffected by the presence of Sb; and (3) Sb-doped GaInP/GaAs tandem cells show promise for achieving efficiencies over 32%.

Olson, J. M.; McMahon, W. E.; Kurtz, S.

2006-05-01T23:59:59.000Z

390

Surface Science Analysis of GaAs Photocathodes Following Sustained Electron Beam Delivery  

SciTech Connect (OSTI)

Degradation of the photocathode materials employed in photoinjectors represents a challenge for sustained operation of nuclear physics accelerators and high power Free Electron Lasers (FEL). Several photocathode degradation processes are suspected, including defect formation by ion back bombardment, photochemistry of surface adsorbed species and irradiation-induced surface defect formation. To better understand the mechanisms of photocathode degradation, we have conducted surface and bulk analysis studies of two GaAs photocathodes removed from the FEL photoinjector after delivering electron beam for a few years. The analysis techniques include Helium Ion Microscopy (HIM), Rutherford Backscattering Spectrometry (RBS), Atomic Force Microscopy (AFM) and Secondary Ion Mass Spectrometry (SIMS). In addition, strained super-lattice GaAs photocathode samples, removed from the CEBAF photoinjector were analyzed using Transmission Electron Microscopy (TEM) and SIMS. This analysis of photocathode degradation during nominal photoinjector operating conditions represents first steps towards developing robust new photocathode designs necessary for generating sub-micron emittance electron beams required for both fourth generation light sources and intense polarized CW electron beams for nuclear and high energy physics facilities.

Shutthanandan, V.; Zhu, Zihua; Stutzman, Marcy L.; Hannon, Fay; Hernandez-Garcia, Carlos; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Thevuthasan, Suntharampillai; Hess, Wayne P.

2012-06-12T23:59:59.000Z

391

Microscopic, electrical and optical studies on InGaN/GaN quantum wells based LED devices  

SciTech Connect (OSTI)

We report here on the micro structural, electronic and optical properties of a GaN-based InGaN/GaN MQW LED grown by the MOVPE method. The present study shows that the threading dislocations present in these LED structures are terminated as V pits at the surface and have an impact on the electrical and optical activity of these devices. It has been pointed that these dislocations were of edge, screw and mixed types. EBIC maps suggest that the electrically active defects are screw and mixed dislocations and behave as nonradiative recombinant centres.

Mutta, Geeta Rani; Venturi, Giulia; Castaldini, Antonio; Cavallini, Anna [Department of Physics and Astronomy, University of Bologna, Viale Carlo Berti Pichat 6/II, 40127 Bologna (Italy); Meneghini, Matteo; Zanoni, Enrico; Meneghesso, Gaudenzio [University of Padova, Department of Information Engineering, via Gradenigo 6/B, Padova 35131 (Italy); Zhu, Dandan; Humphreys, Colin [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom)

2014-02-21T23:59:59.000Z

392

Waveguide effect of GaAsSb quantum wells in a laser structure based on GaAs  

SciTech Connect (OSTI)

The waveguide effect of GaAsSb quantum wells in a semiconductor-laser structure based on GaAs is studied theoretically and experimentally. It is shown that quantum wells themselves can be used as waveguide layers in the laser structure. As the excitation-power density attains a value of 2 kW/cm{sup 2} at liquid-nitrogen temperature, superluminescence at the wavelength corresponding to the optical transition in bulk GaAs (at 835 nm) is observed.

Aleshkin, V. Ya. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)] [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Afonenko, A. A. [Belarussian State University (Belarus)] [Belarussian State University (Belarus); Dikareva, N. V. [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation)] [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation); Dubinov, A. A., E-mail: sanya@ipm.sci-nnov.ru; Kudryavtsev, K. E.; Morozov, S. V. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)] [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Nekorkin, S. M. [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation)] [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation)

2013-11-15T23:59:59.000Z

393

Solid-state lighting : lamp targets and implications for the semiconductor chip.  

SciTech Connect (OSTI)

A quiet revolution is underway. Over the next 5-10 years inorganic-semiconductor-based solid-state lighting technology is expected to outperform first incandescent, and then fluorescent and high-intensity-discharge, lighting. Along the way, many decision points and technical challenges will be faced. To help understand these challenges, the U.S. Department of Energy, the Optoelectronics Industry Development Association and the National Electrical Manufacturers Association recently updated the U.S. Solid-State Lighting Roadmap. In the first half of this paper, we present an overview of the high-level targets of the inorganic-semiconductor part of that update. In the second half of this paper, we discuss some implications of those high-level targets on the GaN-based semiconductor chips that will be the 'engine' for solid-state lighting.

Tsao, Jeffrey Yeenien

2003-08-01T23:59:59.000Z

394

Advances in InGaAs/InP single-photon detector systems for quantum communication  

E-Print Network [OSTI]

Single-photon detectors (SPDs) are the most sensitive instruments for light detection. In the near-infrared range, SPDs based on III-V compound semiconductor avalanche photodiodes have been extensively used during the past two decades for diverse applications due to their advantages in practicality including small size, low cost and easy operation. In the past decade, the rapid developments and increasing demands in quantum information science have served as key drivers to improve the device performance of single-photon avalanche diodes and to invent new avalanche quenching techniques. This Review aims to introduce the technology advances of InGaAs/InP single-photon detector systems in the telecom wavelengths and the relevant quantum communication applications, and particularly to highlight recent emerging techniques such as high-frequency gating at GHz rates and free-running operation using negative-feedback avalanche diodes. Future perspectives of both the devices and quenching techniques are summarized.

Zhang, Jun; Zbinden, Hugo; Pan, Jian-Wei

2015-01-01T23:59:59.000Z

395

Advances in InGaAs/InP single-photon detector systems for quantum communication  

E-Print Network [OSTI]

Single-photon detectors (SPDs) are the most sensitive instruments for light detection. In the near-infrared range, SPDs based on III-V compound semiconductor avalanche photodiodes have been extensively used during the past two decades for diverse applications due to their advantages in practicality including small size, low cost and easy operation. In the past decade, the rapid developments and increasing demands in quantum information science have served as key drivers to improve the device performance of single-photon avalanche diodes and to invent new avalanche quenching techniques. This Review aims to introduce the technology advances of InGaAs/InP single-photon detector systems in the telecom wavelengths and the relevant quantum communication applications, and particularly to highlight recent emerging techniques such as high-frequency gating at GHz rates and free-running operation using negative-feedback avalanche diodes. Future perspectives of both the devices and quenching techniques are summarized.

Jun Zhang; Mark A. Itzler; Hugo Zbinden; Jian-Wei Pan

2015-01-26T23:59:59.000Z

396

Beta-decay branching ratios of 62Ga  

E-Print Network [OSTI]

Beta-decay branching ratios of 62Ga have been measured at the IGISOL facility of the Accelerator Laboratory of the University of Jyvaskyla. 62Ga is one of the heavier Tz = 0, 0+ -> 0+ beta-emitting nuclides used to determine the vector coupling constant of the weak interaction and the Vud quark-mixing matrix element. For part of the experimental studies presented here, the JYFLTRAP facility has been employed to prepare isotopically pure beams of 62Ga. The branching ratio obtained, BR= 99.893(24)%, for the super-allowed branch is in agreement with previous measurements and allows to determine the ft value and the universal Ft value for the super-allowed beta decay of 62Ga.

A. Bey; B. Blank; G. Canchel; C. Dossat; J. Giovinazzo; I. Matea; V. Elomaa; T. Eronen; U. Hager; M. Hakala; A. Jokinen; A. Kankainen; I. Moore; H. Penttila; S. Rinta-Antila; A. Saastamoinen; T. Sonoda; J. Aysto; N. Adimi; G. De France; J. C. Thomas; G. Voltolini; T. Chaventré

2008-04-17T23:59:59.000Z

397

Linear and nonlinear optical properties of GaAs/Al{sub x}Ga{sub 1?x}As/GaAs/Al{sub y}Ga{sub 1?y}As multi-shell spherical quantum dot  

SciTech Connect (OSTI)

In this work, the optical properties of GaAs/Al{sub x}Ga{sub 1?x}As/GaAs/Al{sub y}Ga{sub 1?y}As multi-shell quantum dot heterostructure have been studied as a function of Al doping concentrations for cases with and without a hydrogenic donor atom. It has been observed that the absorption coefficient strength and/or resonant absorption wavelength can be adjusted by changing the Al content of inner-barrier and/or outer-barrier regions. Besides, it has been shown that the donor atom has an important effect on the control of the electronic and optical properties of the structure. The results have been presented as a function of the Al contents of the inner-barrier x and outer-barrier y regions and probable physical reasons have been discussed.

Emre Kavruk, Ahmet, E-mail: aekavruk@selcuk.edu.tr, E-mail: aekavruk@gmail.com; Koc, Fatih [Physics Department, Faculty of Sciences, Selcuk University, 42075 Konya (Turkey); Sahin, Mehmet, E-mail: mehmet.sahin@agu.edu.tr, E-mail: mehsahin@gmail.com [Physics Department, Faculty of Sciences, Selcuk University, 42075 Konya (Turkey); Department of Material Sciences and Nanotechnology Engineering, Abdullah Gul University, Kayseri (Turkey)

2013-11-14T23:59:59.000Z

398

Transverse acoustic actuation of Ni-Mn-Ga single crystals  

E-Print Network [OSTI]

Two methods for the transverse acoustic actuation of {110}-cut Ni-Mn-Ga single crystals are discussed. In this actuation mode, crystals are used that have the {110}- type twinning planes parallel to the base of the crystal. ...

Simon, Jesse Matthew

2007-01-01T23:59:59.000Z

399

Lattice vibrations of pure and doped GaSe  

SciTech Connect (OSTI)

The Bridgman method is used to grow especially undoped and doped single crystals of GaSe. Composition and impurity content of the grown crystals were determined using X-ray fluorescence (XRF) method. X-ray diffraction, Raman scattering, photoluminescence (PL), and IR transmission measurements were performed at room temperature. The long wavelength lattice vibrations of four modifications of GaSe were described in the framework of modified one-layer linear-chain model which also takes into consideration the interaction of the selenium (Se) atom with the second nearest neighbor gallium (Ga) atom in the same layer. The existence of an eight-layer modification of GaSe is suggested and the vibrational frequencies of this modification are explained in the framework of a lattice dynamical model considered in the present work. Frequencies and the type of vibrations (gap, local, or resonance) for the impurity atoms were calculated and compared with the experimental results.

Allakhverdiev, K. [Materials Institute, Marmara Research Center, TUBITAK, Gebze/Kocaeli 41470 (Turkey) and Institute of Physics, Azerbaijan National Academy of Sciences, Baku AZ1143 (Azerbaijan)]. E-mail: kerim.allahverdi@mam.gov.tr; Baykara, T. [Materials Institute, Marmara Research Center, TUBITAK, Gebze/Kocaeli 41470 (Turkey); Ellialtioglu, S. [Department of Physics, Middle East Technical University, Ankara 06531 (Turkey); Hashimzade, F. [Institute of Physics, Azerbaijan National Academy of Sciences, Baku AZ1143 (Azerbaijan); Huseinova, D. [Institute of Physics, Azerbaijan National Academy of Sciences, Baku AZ1143 (Azerbaijan); Kawamura, K. [Institute of Materials Science, University of Tsukuba 305-8573 (Japan); Kaya, A.A. [Materials Institute, Marmara Research Center, TUBITAK, Gebze/Kocaeli 41470 (Turkey); Kulibekov, A.M. [Department of Physics, Mugla University, Mugla 48000 (Turkey); Onari, S. [Institute of Materials Science, University of Tsukuba 305-8573 (Japan)

2006-04-13T23:59:59.000Z

400

Evaporation-based Ge/.sup.68 Ga Separation  

DOE Patents [OSTI]

Micro concentrations of .sup.68 Ga in secular equilibrium with .sup.68 Ge in strong aqueous HCl solution may readily be separated in ionic form from the .sup.68 Ge for biomedical use by evaporating the solution to dryness and then leaching the .sup.68 Ga from the container walls with dilute aqueous solutions of HCl or NaCl. The chloro-germanide produced during the evaporation may be quantitatively recovered to be used again as a source of .sup.68 Ga. If the solution is distilled to remove any oxidizing agents which may be present as impurities, the separation factor may easily exceed 10.sup.5. The separation is easily completed and the .sup.68 Ga made available in ionic form in 30 minutes or less.

Mirzadeh, Saed (Albuquerque, NM); Whipple, Richard E. (Los Alamos, NM); Grant, Patrick M. (Los Alamos, NM); O'Brien, Jr., Harold A. (Los Alamos, NM)

1981-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Nonequilibrium lighting plasmas  

SciTech Connect (OSTI)

In this paper the science of a variety of devices employing nonequilibrium lighting plasmas is reviewed. The devices include the fluorescent lamp, the low-pressure sodium lamp, the neon sign, ultraviolet lamps, glow indicators, and a variety of devices used by spectroscopists, such as the hollow cathode light source. The plasma conditions in representative commercial devices are described. Recent research on the electron gas, the role of heavy particles, spatial and temporal inhomogeneities, and new electrodeless excitation schemes is reviewed. Areas of future activity are expected to be in new applications of high-frequency electronics to commercial devices, new laser-based diagnostics of plasma conditions, and more sophisticated models requiring more reliable and extensive rate coefficient data.

Dakin, J.T. (GE Lighting, Nela Park, Cleveland, OH (US))

1991-12-01T23:59:59.000Z

402

Light cone matrix product  

SciTech Connect (OSTI)

We show how to combine the light-cone and matrix product algorithms to simulate quantum systems far from equilibrium for long times. For the case of the XXZ spin chain at {Delta} = 0.5, we simulate to a time of {approx} 22.5. While part of the long simulation time is due to the use of the light-cone method, we also describe a modification of the infinite time-evolving bond decimation algorithm with improved numerical stability, and we describe how to incorporate symmetry into this algorithm. While statistical sampling error means that we are not yet able to make a definite statement, the behavior of the simulation at long times indicates the appearance of either 'revivals' in the order parameter as predicted by Hastings and Levitov (e-print arXiv:0806.4283) or of a distinct shoulder in the decay of the order parameter.

Hastings, Matthew B [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

403

OLEDS FOR GENERAL LIGHTING  

SciTech Connect (OSTI)

The goal of this program was to reduce the long term technical risks that were keeping the lighting industry from embracing and developing organic light-emitting diode (OLED) technology for general illumination. The specific goal was to develop OLEDs for lighting to the point where it was possible to demonstrate a large area white light panel with brightness and light quality comparable to a fluorescence source and with an efficacy comparable to that of an incandescent source. it was recognized that achieving this would require significant advances in three area: (1) the improvement of white light quality for illumination, (2) the improvement of OLED energy efficiency at high brightness, and (3) the development of cost-effective large area fabrication techniques. The program was organized such that, each year, a ''deliverable'' device would be fabricated which demonstrated progress in one or more of the three critical research areas. In the first year (2001), effort concentrated on developing an OLED capable of generating high illumination-quality white light. Ultimately, a down-conversion method where a blue OLED was coupled with various down-conversion layers was chosen. Various color and scattering models were developed to aid in material development and device optimization. The first year utilized this approach to deliver a 1 inch x 1 inch OLED with higher illumination-quality than available fluorescent sources. A picture of this device is shown and performance metrics are listed. To their knowledge, this was the first demonstration of true illumination-quality light from an OLED. During the second year, effort concentrated on developing a scalable approach to large area devices. A novel device architecture consisting of dividing the device area into smaller elements that are monolithically connected in series was developed. In the course of this development, it was realized that, in addition to being scalable, this approach made the device tolerant to the most common OLED defect--electrical shorts. This architecture enabled the fabrication of a 6 inch x 6 inch OLED deliverable for 2002. A picture of this deliverable is shown and the performance metrics are listed. At the time, this was the highest efficiency, highest lumen output illumination-quality OLED in existence. The third year effort concentrated on improving the fabrication yield of the 6 inch x 6 inch devices and improving the underlying blue device efficiency. An efficiency breakthrough was achieved through the invention of a new device structure such that now 15 lumen per watt devices could be fabricated. A 2 feet x 2 feet OLED panel consisting of sixteen 6 inch x 6 inch high efficiency devices tiled together was then fabricated. Pictures of this panel are shown with performance metrics listed. This panel met all project objectives and was the final deliverable for the project. It is now the highest efficiency, highest lumen output, illumination-quality OLED in existence.

Anil Duggal; Don Foust; Chris Heller; Bill Nealon; Larry Turner; Joe Shiang; Nick Baynes; Tim Butler; Nalin Patel

2004-02-29T23:59:59.000Z

404

Fusion pumped light source  

DOE Patents [OSTI]

Apparatus is provided for generating energy in the form of light radiation. A fusion reactor is provided for generating a long, or continuous, pulse of high-energy neutrons. The neutron flux is coupled directly with the lasing medium. The lasing medium includes a first component selected from Group O of the periodic table of the elements and having a high inelastic scattering cross section. Gamma radiation from the inelastic scattering reactions interacts with the first component to excite the first component, which decays by photon emission at a first output wavelength. The first output wavelength may be shifted to a second output wavelength using a second liquid component responsive to the first output wavelength. The light outputs may be converted to a coherent laser output by incorporating conventional optics adjacent the laser medium.

Pappas, Daniel S. (Los Alamos, NM)

1989-01-01T23:59:59.000Z

405

Anti-phase domains in cubic GaN  

SciTech Connect (OSTI)

The existence of anti-phase domains in cubic GaN grown on 3C-SiC/Si (001) substrates by plasma-assisted molecular beam epitaxy is reported. The influence of the 3C-SiC/Si (001) substrate morphology is studied with emphasis on the anti-phase domains (APDs). The GaN nucleation is governed by the APDs of the substrate, resulting in equal plane orientation and the same anti-phase boundaries. The presence of the APDs is independent of the GaN layer thickness. Atomic force microscopy surface analysis indicates lateral growth anisotropy of GaN facets in dependence of the APD orientation. This anisotropy can be linked to Ga and N face types of the {l_brace}111{r_brace} planes, similar to observations of anisotropic growth in 3C-SiC. In contrast to 3C-SiC, however, a difference in GaN phase composition for the two types of APDs can be measured by electron backscatter diffraction, {mu}-Raman and cathodoluminescence spectroscopy.

Maria Kemper, Ricarda; Schupp, Thorsten; Haeberlen, Maik; Lindner, Joerg; Josef As, Donat [University of Paderborn, Department of Physics, Warburger Str. 100, D-33098 Paderborn (Germany); Niendorf, Thomas; Maier, Hans-Juergen [University of Paderborn, Lehrstuhl fuer Werkstoffkunde, Pohlweg 47-49, D-33098 Paderborn (Germany); Dempewolf, Anja; Bertram, Frank; Christen, Juergen [University of Magdeburg, Institut fuer Festkoerperphysik, P.O. Box 4120, D-39016 Magdeburg (Germany); Kirste, Ronny; Hoffmann, Axel [Technische Universitaet Berlin, Institute of Solid State Physics, Hardenbergstr. 36, D-10623 Berlin (Germany)

2011-12-15T23:59:59.000Z

406

Fabrication of Two-Dimensional Photonic Crystals in AlGaInP/GaInP Membranes by Inductively Coupled Plasma Etching  

E-Print Network [OSTI]

The fabrication process of two-dimensional photonic crystals in an AlGaInP/GaInP multi-quantum-well membrane structure is developed. The process includes high resolution electron-beam lithography, pattern transfer into ...

Chen, A.

407

Epitaxial growth of Cu,,In,Ga...Se2 on GaAs,,110... and A. Rockett  

E-Print Network [OSTI]

. INTRODUCTION The Cu(In, Ga)Se2 CIGS absorber layer in a recent record-efficiency CIGS solar cell1 has a 220.13 Commercially supplied ``epi-ready'' liquid- encapsulated Czo

Rockett, Angus

408

Turbo-Charged Lighting Design  

E-Print Network [OSTI]

TURBO-CHARGED LIGHTING DESIGN William H. Clark II Design Engineer O'Connell Robertson & Assoc Austin/ Texas ABSTRACT The task of the lighting designer has become very complex, involving thousands of choices for fixture types and hundreds...

Clark, W. H. II

409

Influence of stress on optical transitions in GaN nanorods containing a single InGaN/GaN quantum disk  

SciTech Connect (OSTI)

Cathodoluminescence (CL) hyperspectral imaging has been performed on GaN nanorods containing a single InGaN quantum disk (SQD) with controlled variations in excitation conditions. Two different nanorod diameters (200 and 280?nm) have been considered. Systematic changes in the CL spectra from the SQD were observed as the accelerating voltage of the electron beam and its position of incidence are varied. It is shown that the dominant optical transition in the SQD varies across the nanorod as a result of interplay between the contributions of the deformation potential and the quantum-confined Stark effect to the transition energy as consequence of radial variation in the pseudomorphic strain.

Zhuang, Y. D.; Shields, P. A.; Allsopp, D. W. E., E-mail: d.allsopp@bath.ac.uk [Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY (United Kingdom); Bruckbauer, J.; Edwards, P. R.; Martin, R. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

2014-11-07T23:59:59.000Z

410

The first principle study of Ni{sub 2}ScGa and Ni{sub 2}TiGa  

SciTech Connect (OSTI)

We computed the electronic structure, elastic moduli, vibrational properties, and Ni{sub 2}TiGa and Ni{sub 2}ScGa alloys in the cubic L2{sub 1} structure. The obtained equilibrium lattice constants of these alloys are in good agreement with available data. In cubic systems, there are three independent elastic constants, namely C{sub 11}, C{sub 12} and C{sub 44}. We calculated elastic constants in L2{sub 1} structure for Ni{sub 2}TiGa and Ni{sub 2}ScGa using the energy-strain method. The electronic band structure, total and partial density of states for these alloys were investigated within density functional theory using the plane-wave pseudopotential method implemented in Quantum-Espresso program package. From band structure, total and projected density of states, we observed metallic characters of these compounds. The electronic calculation indicate that the predominant contributions of the density of states at Fermi level come from the Ni 3d states and Sc 3d states for Ni{sub 2}TiGa, Ni 3d states and Sc 3d states for Ni{sub 2}ScGa. The computed density of states at Fermi energy are 2.22 states/eV Cell for Ni{sub 2}TiGa, 0.76 states/eV Cell for Ni{sub 2}ScGa. The vibrational properties were obtained using a linear response in the framework at the density functional perturbation theory. For the alloys, the results show that the L2{sub 1} phase is unstable since the phonon calculations have imagine modes.

Özduran, Mustafa [Ahi Evran Üniversitesi Fen Edebiyat Fakültesi Fizik Bölümü, K?r?ehir (Turkey); Turgut, Kemal [Yüksek Lisans Ö?rencisi, K?r?ehir (Turkey); Arikan, Nihat [Ahi Evran Üniversitesi E?itim Fakültesi ?lkö?retim Bölümü, K?r?ehir (Turkey); ?yigör, Ahmet; Candan, Abdullah [Ahi Evran Üniversitesi Merkezi Ara?t?rma Laboratuvar?, K?r?ehir (Turkey)

2014-10-06T23:59:59.000Z

411

Reduced lattice temperature high-speed operation of pseudomorphic InGaAdGaAs field-effect transistors  

E-Print Network [OSTI]

,um GaAs buffer, 170 A Ino.zGao,sAs strained channel, 50 A undoped Ale,,,Ga,,,As undoped spacer, S dimensions of 0.25 x 200 pm and 0.5 X 200 pm with a source-drain spacing of 2 ,um. The MODFETs have gate dimensions of 0.35~ 100 pm and 0.47X 100 pm with a source-drain spacing of 1 ,um. The MISFETs have

Kolodzey, James

412

Faster than Light Quantum Communication  

E-Print Network [OSTI]

Faster than light communication might be possible using the collapse of the quantum wave-function without any accompanying paradoxes.

A. Y. Shiekh

2008-04-05T23:59:59.000Z

413

Webinar: Fuel Cell Mobile Lighting  

Broader source: Energy.gov [DOE]

Video recording of the Fuel Cell Technologies Office webinar, Fuel Cell Mobile Lighting, originally presented on November 13, 2012.

414

Photodetector with enhanced light absorption  

DOE Patents [OSTI]

A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

Kane, James (Lawrenceville, NJ)

1985-01-01T23:59:59.000Z

415

Efficient directional spontaneous emission from an InGaAs/InP heterostructure with an integral parabolic reflector  

SciTech Connect (OSTI)

In order to increase the radiative efficiency and directivity of spontaneous emission from a lattice-matched InGaAs/InP heterostructure, we have polished the substrate into a parabolic reflector. We combine optical and thermal measurements to obtain the absolute external efficiency over a wide range of carrier densities. Using a simple model, the measurement is used to determine interface, radiative, and Auger recombination rates in the active material. At the optimal density, the quantum efficiency exceeds 60{percent} at room temperature. The divergence of the emitted light is less than 20{degree}. In fact, the beam profile is dominated by a 6{degree} wide lobe that can be swept across the field of emission by changing the excitation position. This suggests a way to create an all-electronic scanned light beam. {copyright} {ital 1998 American Institute of Physics.}

Gfroerer, T.H.; Cornell, E.A. [JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, Colorado, 80309-0440 (United States)] [JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, Colorado, 80309-0440 (United States); Wanlass, M.W. [National Renewable Energy Laboratory, Golden, Colorado, 80401 (United States)] [National Renewable Energy Laboratory, Golden, Colorado, 80401 (United States)

1998-11-01T23:59:59.000Z

416

Electroluminescence and phototrigger effect in single crystals of GaS{sub x}Se{sub 1-x} alloys  

SciTech Connect (OSTI)

The effects of switching and electroluminescence as well as the interrelation between these effects in single crystals of GaS{sub x}Se{sub 1-x} alloys are detected and studied. It is established that the threshold voltage for switching depends on temperature, resistivity, and composition of alloys, and also on the intensity and spectrum of photoactive light. As a result, a phototrigger effect is observed; this effect arises under irradiation with light from the fundamental-absorption region. Electroluminescence is observed in the subthreshold region of the current-voltage characteristic; the electroluminescence intensity decreases drastically to zero as the sample is switched from a high-resistivity state to a low-resistivity state. Experimental data indicating that the electroluminescence and the switching effect are based on the injection mechanism (as it takes place in other layered crystals of the III-V type) are reported.

Kyazym-Zade, A. G., E-mail: bsu_aydin@yahoo.com; Salmanov, V. M.; Mokhtari, A. G.; Dadashova, V. V.; Agaeva, A. A. [Baku State University (Azerbaijan)

2008-05-15T23:59:59.000Z

417

60 GHz Harmonic Optoelectronic Up-Conversion Using an InAlAs/InGaAs Metamorphic High-Electron-Mobility Transistor on a GaAs Substrate  

E-Print Network [OSTI]

60 GHz Harmonic Optoelectronic Up-Conversion Using an InAlAs/InGaAs Metamorphic High optoelectronic up-conversion using an InAlAs/InGaAs metamorphic high-electron-mobility transistor (HEMT) on a Ga 1 GHz signals into a 60 GHz band. After investigating the dependences of optoelectronic mixing

Choi, Woo-Young

418

Organometallic Vapor Phase Epitaxy of n-GaSb and n-GaInAsSb for Low Resistance Ohmic Contacts  

SciTech Connect (OSTI)

A comparison of n-GaSb and n-GaInAsSb epilayers for ohmic contacts in GaSb-based devices is studied. The epilayers were grown by organometallic vapor phase epitaxy and doped with Te. At similar electron concentrations, the atomic Te concentration, as determined by secondary ion mass spectroscopy, is more than 2 times higher in n-GaSb compared to n-GaInAsSb. In addition, the electron mobility is lower in n-GaSb than n-GaInAsSb at similar electron concentrations. The electron concentration saturates at about 1.3 x 10{sup 18} cm{sup -3} for n-GaSb, but linearly increases for n-GaInAsSb. Pd/Ge/Au/Pt/Au metallization was studied for ohmic contacts. A specific contact resistivity of 1 x 10{sup -5}{Omega}-cm{sup 2} for n-GaSb was measured. The specific contact resistivity can be greatly improved by contacting n-GaInAsSb, and a significantly lower specific contact resistivity of 2 x 10{sup -6} {Omega}-cm{sup 2} for n-GaInAsSb was measured.

C.A. Wang; D.A. Shiau; R.K. Huang; C.T. Harris; M.K. Connors

2003-07-10T23:59:59.000Z

419

The crucial role of doping for high repetition rate monolithic mode locking of multiple quantum well GaAs/AlGaAs lasers  

E-Print Network [OSTI]

have been operated in GaAs/AlGaAs and InP/InGaAsP mul- tiple quantum well MQW materials showed no evidence of mode-locked operation. Band-edge absorption spectra are also presented which

420

MANDATORY MEASURES OUTDOOR LIGHTING CONTROLS  

E-Print Network [OSTI]

MANDATORY MEASURES OUTDOOR LIGHTING CONTROLS (Reference: Sub-Chapter 4, Section 130.2) #12;SECTION level of each multi-tier garage. · General lighting must have occupant sensing controls with at least one control step between 20% and 50% of design lighting power · No more than 500 watts of rated

California at Davis, University of

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

MANDATORY MEASURES OUTDOOR LIGHTING CONTROLS  

E-Print Network [OSTI]

MANDATORY MEASURES OUTDOOR LIGHTING CONTROLS (Reference: Sub-Chapter 4, Section 130.2) #12;SECTION 5 Additions and Alterations Any alteration that increases the connected lighting load must meet all No measures required OUTDOOR LIGHTING11/20/2014 #12;SECTION 5 BACKLIGHT, UPLIGHT, AND GLARE (BUG) RATINGS

California at Davis, University of

422

MANDATORY MEASURES OUTDOOR LIGHTING CONTROLS  

E-Print Network [OSTI]

MANDATORY MEASURES OUTDOOR LIGHTING CONTROLS (Reference: Sub-Chapter 4, Section 130.2) #12;SECTION performance in relation to lighting trespass, sky glow, and high angle brightness. This is necessary in order to reduce light pollution, which has a negative effect on wildlife and the surrounding environments

California at Davis, University of

423

Arnold Schwarzenegger, LIGHTING RESEARCH PROGRAM  

E-Print Network [OSTI]

;#12;Prepared By: Lighting Research Center Andrew Bierman, Project Lead Troy, New York 12180 Managed ByArnold Schwarzenegger, Governor LIGHTING RESEARCH PROGRAM PROJECT 3.2 ENERGY EFFICIENT LOAD- SHEDDING LIGHTING TECHNOLOGY Prepared For: California Energy Commission Public Interest Energy Research

424

STATE OF CALIFORNIA RESIDENTIAL LIGHTING  

E-Print Network [OSTI]

STATE OF CALIFORNIA RESIDENTIAL LIGHTING CEC-CF-6R-LTG-01 (Revised 08/09) CALIFORNIA ENERGY COMMISSION INSTALLATION CERTIFICATE CF-6R-LTG-01 Residential Lighting (Page 1 of 6) Site Address: Enforcement Agency: Permit Number: 2008 Residential Compliance Forms August 2009 1. Kitchen Lighting Does project

425

Low temperature carrier redistribution dynamics in InGaN/GaN quantum wells  

SciTech Connect (OSTI)

We have studied the carrier recombination dynamics in an InGaN/GaN multiple quantum well structure as a function of emission energy and excitation density between temperatures of 10?K and 100?K. Under relatively low levels of excitation, the photoluminescence (PL) intensity and decay time of emission on the high energy side of the luminescence spectrum decrease strongly between 10?K and 50?K. In contrast, for emission detected on the low energy side of the spectrum, the PL intensity and decay time increase over the same temperature range. These results are consistent with a thermally activated carrier redistribution process in which the (temperature dependent) average timescale for carrier transfer into or out of a localised state depends on the energy of the given state. Thus, the transfer time out of shallow, weakly localised states is considerably shorter than the arrival time into more deeply localised states. This picture is consistent with carriers hopping between localisation sites in an uncorrelated disorder potential where the density of localised states decreases with increasing localisation depth, e.g., a exponential or Gaussian distribution resulting from random alloy disorder. Under significantly higher levels of excitation, the increased occupation fraction of the localised states results in a greater average separation distance between unoccupied localised states, causing a suppression of the spectral and dynamic signatures of the hopping transfer of carriers.

Badcock, T. J., E-mail: Thomas.badcock@crl.toshiba.co.uk; Dawson, P.; Davies, M. J. [School of Physics and Astronomy, Photon Science Institute, Alan Turing Building, University of Manchester, Manchester M13 9PL (United Kingdom); Kappers, M. J.; Massabuau, F. C.-P.; Oehler, F.; Oliver, R. A.; Humphreys, C. J. [Department of Materials Science and Metallurgy, 27 Charles Babbage Road, University of Cambridge, Cambridge CB3 0FS (United Kingdom)

2014-03-21T23:59:59.000Z

426

Testing of ethylene propylene seals for the GA-4/GA-9 casks  

SciTech Connect (OSTI)

The primary O-ring seal of the GA-4 and GA-9 casks was tested for leakage with a full-scale mockup of the cask lid and flange. Tests were performed at temperatures of ambient, {minus}41{degrees}, 121{degrees}, and 193{degrees}C. Shim plates between the lid and flange simulated gaps caused by thermal distortion. The testing used a helium mass spectrometer leak detector (MSLD). Results showed that the primary seal was leaktight for all test conditions. Helium permeation through the seal began in 13--23 minutes for the ambient tests and in 1--2 minutes for the tests at elevated temperatures. After each test several hours of the pumping were typically required to reduce the MSLD background reading to an acceptable level for the next test, indicating that the seal had become saturated with helium. To verify that the test results showed permeation and not real leakage, several response checks were conducted in which a calibrated leak source was inserted in the detector line near the seal. When the leak source was activated the detector responded within seconds.

Boonstra, R.H.

1993-08-01T23:59:59.000Z

427

Ultra low-resistance palladium silicide Ohmic contacts to lightly doped n-J. D. Yearsley, J. C. Lin, E. Hwang, S. Datta, and S. E. Mohney  

E-Print Network [OSTI]

Ultra low-resistance palladium silicide Ohmic contacts to lightly doped n- InGaAs J. D. Yearsley, J at the metal-germanium interface by the formation of epitaxial nickel digermanide NiGe2 using pulsed laser resistivity of metals on nitrogen-doped cuprous oxide (Cu2O) thin-films J. Appl. Phys. 112, 084508 (2012

Yener, Aylin

428

Amber-green light-emitting diodes using order-disorder Al[subscript x]In[subscript 1?x]P heterostructures  

E-Print Network [OSTI]

We demonstrate amber-green emission from Al[subscript x]In[subscript 1– x]P light-emitting diodes (LEDs) with luminescence peaked at 566?nm and 600?nm. The LEDs are metamorphically grown on GaAs substrates via a graded ...

Christian, Theresa M.

429

Contribution of alloy clustering to limiting the two-dimensional electron gas mobility in AlGaN/GaN and InAlN/GaN heterostructures: Theory and experiment  

SciTech Connect (OSTI)

The influence of alloy clustering on fluctuations in the ground state energy of the two-dimensional electron gas (2DEG) in AlGaN/GaN and InAlN/GaN heterostructures is studied. We show that because of these fluctuations, alloy clustering degrades the mobility even when the 2DEG wavefunction does not penetrate the alloy barrier unlike alloy disorder scattering. A comparison between the results obtained for AlGaN/GaN and InAlN/GaN heterostructures shows that alloy clustering limits the 2DEG mobility to a greater degree in InAlN/GaN heterostructures. Our study also reveals that the inclusion of an AlN interlayer increases the limiting mobility from alloy clustering. Moreover, Atom probe tomography is used to demonstrate the random nature of the fluctuations in the alloy composition.

Ahmadi, Elaheh; Mishra, Umesh K. [Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106 (United States); Chalabi, Hamidreza [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305 (United States); Kaun, Stephen W.; Shivaraman, Ravi; Speck, James S. [Materials Department, University of California, Santa Barbara, California 93106 (United States)

2014-10-07T23:59:59.000Z

430

Pedestrian Friendly Outdoor Lighting  

SciTech Connect (OSTI)

This GATEWAY report discusses the problems of pedestrian lighting that occur with all technologies with a focus on the unique optical options and opportunities offered by LEDs through the findings from two pedestrian-focused projects, one at Stanford University in California, and one at the Chautauqua Institution in upstate New York. Incorporating user feedback this report reviews the tradeoffs that must be weighed among visual comfort, color, visibility, efficacy and other factors to stimulate discussion among specifiers, users, energy specialists, and in industry in hopes that new approaches, metrics, and standards can be developed to support pedestrian-focused communities, while reducing energy use.

Miller, Naomi J.; Koltai, Rita; McGowan, Terry

2013-12-31T23:59:59.000Z

431

Advances in Lighting  

E-Print Network [OSTI]

colour rendition. The quartz-halogen incandescent lam s operate at higher temperatures, and have a somewhat higher efficacy, but they are rarely used except for special applicati ns. 3-2 High Intensity Discharge Lamps. Mercury is the grandfather... of the H.I.D. lamps. Its blue-green light, has been used almost exclusively for streetlighti and, often with colour-improving phospho it is still being used in industrial and commercial applications. Reactor-type ballasted mercury lamps can now...

Tumber, A. J.

1981-01-01T23:59:59.000Z

432

Lights, Conformational Change... Action!  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: VegetationEquipment Surfaces and Interfaces Sample6, 2011 LawrenceEfeedstocksHomesLighting the

433

Lighting | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating Solar Powerstories on climateJuno Beach,October,Lighthouse Solar Jump to:Lighting Jump

434

Ecological Consequences of Artificial Night Lighting  

E-Print Network [OSTI]

of Artificial Night Lighting Catherine Rich and Travisof artificial night lighting. This book provides editedage of modern urban lighting was ushered in. Coincidentally,

Piselli, Kathy

2006-01-01T23:59:59.000Z

435

LIGHTING CONTROLS: SURVEY OF MARKET POTENTIAL  

E-Print Network [OSTI]

REFERENCES Task Report to Lighting Systems Research,Berkeley Laboratory, "Lighting Control System Market1980). Task Report to Lighting Systems Research, Lawrence

Verderber, R.R.

2010-01-01T23:59:59.000Z

436

Demand Responsive Lighting: A Scoping Study  

E-Print Network [OSTI]

3 3.0 Previous Experience with Demand Responsive Lighting11 4.3. Prevalence of Lighting13 4.4. Impact of Title 24 on Lighting

Rubinstein, Francis; Kiliccote, Sila

2007-01-01T23:59:59.000Z

437

Municipal Consortium LED Street Lighting Workshop Presentations...  

Broader source: Energy.gov (indexed) [DOE]

A Rational View of LM-79 Reports, IES Files, and Product Variation Gary Steinberg, GE Lighting Solutions Solid-State Street Lighting: Calculating Light Loss Factors Dana Beckwith,...

438

Municipal Consortium LED Street Lighting Workshop Presentations...  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

National Association of Energy Services Companies Calculating Light Loss Factors for Solid-State Lighting Systems Chad Stalker, Philips Lumileds Lighting Intro to MSSLC's...

439

Sandia National Laboratories: Light Creation Materials  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

TechnologiesLight Creation Materials Light Creation Materials Overview of SSL Light Creation Materials Different families of inorganic semiconductor materials can...

440

Photon echo studies of photosynthetic light harvesting  

E-Print Network [OSTI]

of the B800-B820 light-harvesting complex. Proc Natl Acadphotosynthetic light harvesting Elizabeth L. Read Æ Hohjaitransfer events in light harvesting. Here, we outline the

Read, Elizabeth L.; Lee, Hohjai; Fleming, Graham R.

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Sandia National Laboratories: Light Creation Materials  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

EFRCOverviewLight Creation Materials Light Creation Materials Overview of SSL Light Creation Materials Different families of inorganic semiconductor materials can contribute to...

442

Efficiency Improvement of Nitride-Based Solid State Light Emitting Materials -- CRADA Final Report  

SciTech Connect (OSTI)

The development of In{sub x}Ga{sub 1-x} N/GaN thin film growth by Molecular Beam Epitaxy has opened a new route towards energy efficient solid-state lighting. Blue and green LED's became available that can be used to match the whole color spectrum of visible light with the potential to match the eye response curve. Moreover, the efficiency of such devices largely exceeds that of incandescent light sources (tungsten filaments) and even competes favorably with lighting by fluorescent lamps. It is, however, also seen in Figure 1 that it is essential to improve on the luminous performance of green LED's in order to mimic the eye response curve. This lack of sufficiently efficient green LED's relates to particularities of the In{sub x}Ga{sub 1-x}N materials system. This ternary alloy system is polar and large strain is generated during a lattice mismatched thin film growth because of the significantly different lattice parameters between GaN and InN and common substrates such as sapphire. Moreover, it is challenging to incorporate indium into GaN at typical growth temperatures because a miscibility gap exists that can be modified by strain effects. As a result a large parameter space needs exploration to optimize the growth of In{sub x}Ga{sub 1-x}N and to date it is unclear what the detailed physical processes are that affect device efficiencies. In particular, an inhomogeneous distribution indium in GaN modifies the device performance in an unpredictable manner. As a result technology is pushed forward on a trial and error basis in particular in Asian countries such as Japan and Korea, which dominate the market and it is desirable to strengthen the competitiveness of the US industry. This CRADA was initiated to help Lumileds Lighting/USA boosting the performance of their green LED's. The tasks address the distribution of the indium atoms in the active area of their blue and green LED's and its relation to internal and external quantum efficiencies. Procedures to measure the indium distribution with near atomic resolution were developed and applied to test samples and devices that were provided by Lumilids. Further, the optical performance of the device materials was probed by photoluminescence, electroluminescence and time resolved optical measurements. Overall, the programs objective is to provide a physical basis for the development of a simulation program that helps making predictions to improve the growth processes such that the device efficiency can be increased to about 20%. Our study addresses all proposed aspects successfully. Carrier localization, lifetime and recombination as well as the strain-induced generation of electric fields were characterized and modeled. Band gap parameters and their relation to the indium distribution were characterized and modeled. Electron microscopy was developed as a unique tool to measure the formation of indium clusters on a nanometer length scale and it was demonstrated that strain induced atom column displacements can reliably be determined in any materials system with a precision that approaches 2 pm. The relation between the local indium composition x and the strain induced lattice constant c(x) in fully strained In{sub x}Ga{sub 1-x}N quantum wells was found to be: c(x) = 0.5185 + {alpha}x with {alpha} = 0.111 nm. It was concluded that the local indium concentration in the final product can be modulated by growth procedures in a predictable manner to favorably affect external quantum efficiencies that approached target values and that internal quantum efficiencies exceeded them.

Kisielowski, Christian; Weber, Eicke

2010-05-13T23:59:59.000Z

443

Nano-scale luminescence characterization of individual InGaN/GaN quantum wells stacked in a microcavity using scanning transmission electron microscope cathodoluminescence  

SciTech Connect (OSTI)

Using cathodoluminescence spectroscopy directly performed in a scanning transmission electron microscope at liquid helium temperatures, the optical and structural properties of a 62 InGaN/GaN multiple quantum well embedded in an AlInN/GaN based microcavity are investigated at the nanometer scale. We are able to spatially resolve a spectral redshift between the individual quantum wells towards the surface. Cathodoluminescence spectral linescans allow directly visualizing the critical layer thickness in the quantum well stack resulting in the onset of plastic relaxation of the strained InGaN/GaN system.

Schmidt, Gordon, E-mail: Gordon.Schmidt@ovgu.de; Müller, Marcus; Veit, Peter; Bertram, Frank; Christen, Jürgen [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg (Germany); Glauser, Marlene; Carlin, Jean-François; Cosendey, Gatien; Butté, Raphaël; Grandjean, Nicolas [Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

2014-07-21T23:59:59.000Z

444

Suppression of nuclear spin diffusion at a GaAs/AlGaAs interface measured with a single quantum dot nano-probe  

E-Print Network [OSTI]

Nuclear spin polarization dynamics are measured in optically pumped individual GaAs/AlGaAs interface quantum dots by detecting the time-dependence of the Overhauser shift in photoluminescence (PL) spectra. Long nuclear polarization decay times of ~ 1 minute have been found indicating inefficient nuclear spin diffusion from the GaAs dot into the surrounding AlGaAs matrix in externally applied magnetic field. A spin diffusion coefficient two orders lower than that previously found in bulk GaAs is deduced.

A. E. Nikolaenko; E. A. Chekhovich; M. N. Makhonin; I. W. Drouzas; A. B. Vankov; J. Skiba-Szymanska; M. S. Skolnick; P. Senellart; A. Lemaitre; A. I. Tartakovskii

2009-01-15T23:59:59.000Z

445

Maskless lateral epitaxial overgrowth of GaN on sapphire  

SciTech Connect (OSTI)

The authors demonstrate a technique of lateral epitaxial overgrowth (LEO) of GaN, termed maskless LEO, in which no mask is deposited prior to LEO regrowth. Instead, a bulk (> 2 {micro}m) GaN layer on sapphire is selectively dry etched, leaving {approximately} 5 {micro}m-wide stripe mesas oriented in the <10{bar 1}0>{sub GaN} direction, with a 20 {micro}m period. These stripes serve as seeds for LEO GaN growth, which proceeds from the tops of the stripes and expands laterally, resulting in a T, or overhang, morphology. As for LEO over an SiO{sub 2} mask, significant defect reduction (from {approximately} 10{sup 9} cm{sup {minus}2} to {approximately} 10{sup 6} cm{sup {minus}2}) is observed in cross-sectional transmission electron microscopy (TEM). Atomic force microscopy of the top surface of the LEO GaN reveals that no threading dislocations with screw component terminate at the surfaces of laterally overgrown regions. X-ray diffraction measurements reveal that the wings exhibit a crystallographic tilt away from the seed regions in an azimuth perpendicular to the stripe direction; the tilt angle ({approximately} 0.4--0.5{degree}) is relatively independent of growth temperature and wing aspect ratio.

Fini, P.; Marchand, H.; Ibbetson, J.P.; Moran, B.; Zhao, L.; Denbaars, S.P.; Speck, J.S.; Mishra, U.K.

1999-07-01T23:59:59.000Z

446

Pulsed laser annealing of Be-implanted GaN  

SciTech Connect (OSTI)

Postimplantation thermal processing of Be in molecular-beam-epitaxy-grown GaN by rapid thermal annealing (RTA) and pulsed laser annealing (PLA) was investigated. It has been found that the activation of Be dopants and the repair of implantation-induced defects in GaN films cannot be achieved efficiently by conventional RTA alone. On the other hand, good dopant activation and surface morphology and quality were obtained when the Be-implanted GaN film was annealed by PLA with a 248 nm KrF excimer laser. However, observations of off-resonant micro-Raman and high-resolution x-ray-diffraction spectra indicated that crystal defects and strain resulting from Be implantation were still existent after PLA, which probably degraded the carrier mobility and limited the activation efficiency to some extent. This can be attributed to the shallow penetration depth of the 248 nm laser in GaN, which only repaired the crystal defects in a thin near-surface layer, while the deeper defects were not annealed out well. This situation was significantly improved when the Be-implanted GaN was subjected to a combined process of PLA followed by RTA, which produced good activation of the dopants, good surface morphology, and repaired bulk and surface defects well.

Wang, H.T.; Tan, L.S.; Chor, E.F. [Centre for Optoelectronics, Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

2005-11-01T23:59:59.000Z

447

Intrinsic nature of visible-light absorption in amorphous semiconducting oxides  

SciTech Connect (OSTI)

To enlighten microscopic origin of visible-light absorption in transparent amorphous semiconducting oxides, the intrinsic optical property of amorphous InGaZnO{sub 4} is investigated by considering dipole transitions within the quasiparticle band structure. In comparison with the crystalline InGaZnO{sub 4} with the optical gap of 3.6 eV, the amorphous InGaZnO{sub 4} has two distinct features developed in the band structure that contribute to significant visible-light absorption. First, the conduction bands are down-shifted by 0.55 eV mainly due to the undercoordinated In atoms, reducing the optical gap between extended states to 2.8 eV. Second, tail states formed by localized oxygen p orbitals are distributed over ?0.5 eV near the valence edge, which give rise to substantial subgap absorption. The fundamental understanding on the optical property of amorphous semiconducting oxides based on underlying electronic structure will pave the way for resolving instability issues in recent display devices incorporating the semiconducting oxides.

Kang, Youngho; Song, Hochul; Han, Seungwu, E-mail: hansw@snu.ac.kr [Department of Materials Science and Engineering, Seoul National University, Seoul 151-755 (Korea, Republic of); Nahm, Ho-Hyun [Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747 (Korea, Republic of); Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Jeon, Sang Ho; Cho, Youngmi [CAE Team, Samsung Display Co., Ltd, 95 Samsung 2-ro, Giheung-gu, Youngin-City, Gyeonggi-Do 446-711 (Korea, Republic of)

2014-03-01T23:59:59.000Z

448

Dark defects in InGaAsP/InP double heterostructure lasers under accelerated aging  

SciTech Connect (OSTI)

Degradation modes due to dark defects under accelerated aging for InGaAsP/InP double heterostructure lasers are investigated by monitoring pulse threshold current, leak current, absorption coefficient, gain factor, and electroluminescence topograph. Most of the dark defects are dark spot defects (DSD's) and there are only few <100> dark line defects. At the initial stage of the degradation, these dark defects scarcely absorb the emitted light, and the reduction of gain factor causes the increase of pulse threshold current. After this stage, dark defects begin to act as absorber of the emitted light. The generation time of such DSD's strongly depends on the injected current density but only weakly on the junction temperature in the range of 25/sup 0/ to 250/sup 0/C. The activation energies for the generation time of the first dark spot defect and the growing speed of <100> dark line defects are estimated to be 0.16 and 0.2 eV, respectively.

Fukuda, M.; Wakita, K.; Iwane, G.

1983-03-01T23:59:59.000Z

449

Energy Savings Estimates of Light Emitting Diodes in Niche Lighting...  

Office of Environmental Management (EM)

in Niche Lighting Applications Prepared for: Building Technologies Program Office of Energy Efficiency and Renewable Energy U.S. Department of Energy Prepared by: Navigant...

450

Light modulating device  

DOE Patents [OSTI]

In a device for transmitting light, means for controlling the transmissivity of the device, including a ceramic, reversibly electrochromic, crystalline element having a highly reflective state when injected with electrons and charge compensating ions and a highly transmissive state when the electrons and ions are removed, the crystalline element being characterized as having a reflectivity of at least 50% in the reflective state and not greater than 10% in the transmissive state, and means for modulating the crystalline element between the reflective and transmissive states by injecting ions into the crystalline element in response to an applied electrical current of a first polarity and removing the ions in response to an applied electrical current of a second polarity.

Rauh, R. David (Newton, MA); Goldner, Ronald B. (Lexington, MA)

1989-01-01T23:59:59.000Z

451

Light modulating device  

DOE Patents [OSTI]

In a device for transmitting light, means for controlling the transmissivity of the device, including a ceramic, reversibly electrochromic, crystalline element having a highly reflective state when injected with electrons and charge compensating ions and a highly transmissive state when the electrons and ions are removed, the crystalline element being characterized as having a reflectivity of at least 50% in the reflective state and not greater than 10% in the transmissive state, and means for modulating the crystalline element between the reflective and transmissive states by injecting ions into the crystalline element in response to an applied electrical current of a first polarity and removing the ions in response to an applied electrical current of a second polarity are disclosed. 1 fig.

Rauh, R.D.; Goldner, R.B.

1989-12-26T23:59:59.000Z

452

Energy and lighting  

SciTech Connect (OSTI)

Advances in research for new types of lighting with increased efficacies (lumens/watt) are discussed in the following areas: (1) high-frequency, solid-state ballasts, (2) isotopic enhancement of mercury isotopes, (3) magnetic augmentation, (4) electrodeless, ultra-high frequency, (5) tuned phosphors, (6) two-photon phosphors, (7) heat mirrors, and (3) advanced control circuits to take advantage of daylight and occupancy. As of 1985, improvements in efficacy have been accomplished on an economic basis to save energy for (1) high-frequency ballasts (25%), (2) isotopic enhancement (5%), and (8) advanced control circuits (up to 50%). Most of these advances depend on a deeper understanding of the weakly ionized plasma as a radiating and diffusing medium. 3 figures, 4 tables.

Berman, S.

1985-01-01T23:59:59.000Z

453

Cost effective lighting  

SciTech Connect (OSTI)

Long-life replacement lamps for the incandescent lamp have been evaluated with regard to their cost effectiveness. The replacements include the use of energy buttons that extend lamp life as well as an adaptive fluorescent circline lamp that will fit into existing incandescent lamp sockets. The initial, operating, and replacement costs for one million lumen-hours are determined for each lamp system. We find the most important lighting cost component is the operating cost. Using lamps that are less efficient or devices that cause lamps to operate less efficiently are not cost-effective. The adaptive fluorescent circline lamp, even at an initial cost of $15.00, is the most cost effective source of illumination compared to the incandescent lamp and lamp systems examined. 3 refs., 6 tabs.

Morse, O.; Verderber, R.

1987-07-01T23:59:59.000Z

454

Posters | Posters --721 Exploring lighting cultures  

E-Print Network [OSTI]

Posters | Posters -- 721 Exploring lighting cultures Beyond light and emotions Vincent LAGANIER 1 , Jasmine van der POL 2 1. Lighting Applications Services (LiAS), Philips Lighting, France vincent.laganier@philips.com 2

Boyer, Edmond

455

Creative and Constructive Play with Light  

E-Print Network [OSTI]

children identify objects with these properties. Predict what materials light will pass through. Use paint and mixing light. Mixing paint creates a muddy brown or black. Mixing light creates white light

456

GaAs-based high temperature electrically pumped polariton laser  

SciTech Connect (OSTI)

Strong coupling effects and polariton lasing are observed at 155?K with an edge-emitting GaAs-based microcavity diode with a single Al{sub 0.31}Ga{sub 0.69}As/Al{sub 0.41}Ga{sub 0.59}As quantum well as the emitter. The threshold for polariton lasing is observed at 90?A/cm{sup 2}, accompanied by a reduction of the emission linewidth to 0.85?meV and a blueshift of the emission wavelength by 0.89?meV. Polariton lasing is confirmed by the observation of a polariton population redistribution in momentum space and spatial coherence. Conventional photon lasing is recorded in the same device at higher pump powers.

Baten, Md Zunaid; Bhattacharya, Pallab, E-mail: pkb@eecs.umich.edu; Frost, Thomas; Deshpande, Saniya; Das, Ayan [Center for Photonic and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Lubyshev, Dimitri; Fastenau, Joel M.; Liu, Amy W. K. [IQE, Inc., 119 Technology Drive, Bethlehem, Pennsylvania 18015 (United States)

2014-06-09T23:59:59.000Z

457

Simulation of Npn and Pnp AlGaN/GaN heterojunction bipolar transistors performances: Limiting factors and optimum design  

SciTech Connect (OSTI)

The performance capabilities of Npn and Pnp AlGaN/GaN heterojunction bipolar transistors have been investigated by using a drift-diffusion transport model. Numerical results have been employed to study the effect of the p-type Mg doping and its incomplete ionization on device performance. The high base resistance induced by the deep acceptor level is found to be the cause of limited current gain values for Npn devices. Several computation approaches have been considered to improve their performance. Reasonable improvement of the DC current gain {beta} is observed by realistically reducing the base thickness in accordance with processing limitations. Base transport enhancement is also predicted by the introduction of a quasi-electric field in the base. The impact of the base resistivity on high-frequency characteristics is investigated for Npn AlGaN/GaN devices. Optimized predictions with maximum oscillation frequency value as high as f{sub MAX} = 20 GHz and a unilateral power gain--U = 25 dB make this bipolar GaN-based technology compatible with communication applications. Simulation results reveal that the restricted amount of free carriers from the p-doped emitter limits Pnp's DC performances operating in common emitter configuration. A preliminary analysis of r.f. characteristics for the Pnp counterpart indicates limited performance mainly caused by the degraded hole mobility.

MONIER,C.; REN,F.; HAN,JUNG; CHANG,PING-CHIH; SHUL,RANDY J.; LEE,K.P.; ZHANG,A.P.; BACA,ALBERT G.; PEARTON,S.J.

2000-04-25T23:59:59.000Z

458

The impact of trench defects in InGaN/GaN light emitting diodes and implications for the “green gap” problem  

E-Print Network [OSTI]

of Physics and Astronomy, Alan Turing Building, University of Manchester, Manchester M13 9PL, UK 3 Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, Leo-Brandt- Straße, D-52425 Jülich, Germany 4 Monash...

Massabuau, F. C.-P.; Davies, M. J.; Oehler, F.; Pamenter, S. K.; Thrush, E. J.; Kappers, M. J.; Kovács, A.; Williams, T.; Hopkins, M. A.; Humphreys, C. J.; Dawson, P.; Dunin-Borkowski, R. E.; Etheridge, J.; Allsopp, D. W. E.; Oliver, R. A.

2014-09-19T23:59:59.000Z

459

Gas-source molecular beam epitaxial growth and characterization of the (Al,In,Ga)NP/GaP material system and Its applications to light-emitting diodes  

E-Print Network [OSTI]

T.P. , IEE Proceedings-Optoelectronics 144, 1 (1997). Kishof Energy (BTS) and the Optoelectronics Industry Developmentin semiconductor optoelectronics in recent years. Within two

Odnoblyudov, Vladimir

2006-01-01T23:59:59.000Z

460

Charge Profiling of the p-AlGaN Electron Blocking Layer in AlGaInN Light Emitting Diode Structures  

E-Print Network [OSTI]

-layers. Placement, doping, and dimensions thereof are deemed critical to the stabilization of the injection-3 . A spacer layer of 20 ­ 100 nm separates the n-side and the quantum well region. Like the barrier

Wetzel, Christian M.

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Investigation of efficiency droop for InGaN-based UV light-emitting diodes with InAlGaN barrier  

E-Print Network [OSTI]

applications in photocatalytic deodorizing such as air conditioner,1 and there have been interests in solid

462

Mid-ultraviolet light-emitting diode detects dipicolinic acid.  

SciTech Connect (OSTI)

Dipicolinic acid (DPA, 2,6-pyridinedicarboxylic acid) is a substance uniquely present in bacterial spores such as that from anthrax (B. anthracis). It is known that DPA can be detected by the long-lived fluorescence of its terbium chelate; the best limit of detection (LOD) reported thus far using a large benchtop gated fluorescence instrument using a pulsed Xe lamp is 2 nM. We use a novel AlGaN light-emitting diode (LED) fabricated on a sapphire substrate that has peak emission at 291 nm. Although the overlap of the emission band of this LED with the absorption band of Tb-DPA ({lambda}{sub max} doublet: 273, 279 nm) is not ideal, we demonstrate that a compact detector based on this LED and an off-the-shelf gated photodetection module can provide an LOD of 0.4 nM, thus providing a basis for convenient early warning detectors.

Bogart, Katherine Huderle Andersen; Lee, Stephen Roger; Temkin, Henryk (Texas Tech University, Lubbock, TX); Crawford, Mary Hagerott; Dasgupta, Purnendu K. (Texas Tech University, Lubbock, TX); Li, Qingyang (Texas Tech University, Lubbock, TX); Allerman, Andrew Alan; Fischer, Arthur Joseph

2005-06-01T23:59:59.000Z

463

Embodied Energy and Off-Grid Lighting  

E-Print Network [OSTI]

as a point of comparison with LED lighting product embodieda fairer comparison between off- grid LED lighting and other

Alstone, Peter

2012-01-01T23:59:59.000Z

464

Overcoming Common Pitfalls: Energy Efficient Lighting Projects...  

Broader source: Energy.gov (indexed) [DOE]

Overcoming Common Pitfalls: Energy Efficient Lighting Projects Overcoming Common Pitfalls: Energy Efficient Lighting Projects Transcript Presentation More Documents & Publications...

465

Automatic Mechetronic Wheel Light Device  

DOE Patents [OSTI]

A wheel lighting device for illuminating a wheel of a vehicle to increase safety and enhance aesthetics. The device produces the appearance of a "ring of light" on a vehicle's wheels as the vehicle moves. The "ring of light" can automatically change in color and/or brightness according to a vehicle's speed, acceleration, jerk, selection of transmission gears, and/or engine speed. The device provides auxiliary indicator lights by producing light in conjunction with a vehicle's turn signals, hazard lights, alarm systems, and etc. The device comprises a combination of mechanical and electronic components and can be placed on the outer or inner surface of a wheel or made integral to a wheel or wheel cover. The device can be configured for all vehicle types, and is electrically powered by a vehicle's electrical system and/or battery.

Khan, Mohammed John Fitzgerald (Silver Spring, MD)

2004-09-14T23:59:59.000Z

466

Simple intrinsic defects in GaAs : numerical supplement.  

SciTech Connect (OSTI)

This Report presents numerical tables summarizing properties of intrinsic defects in gallium arsenide, GaAs, as computed by density functional theory. This Report serves as a numerical supplement to the results published in: P.A. Schultz and O.A. von Lilienfeld, 'Simple intrinsic defects in GaAs', Modelling Simul. Mater. Sci Eng., Vol. 17, 084007 (2009), and intended for use as reference tables for a defect physics package in device models. The numerical results for density functional theory calculations of properties of simple intrinsic defects in gallium arsenide are presented.

Schultz, Peter Andrew

2012-04-01T23:59:59.000Z

467

AlP/GaP distributed Bragg reflectors  

SciTech Connect (OSTI)

Distributed Bragg reflectors with high reflectivity bands centered at wavelengths from 530 to 690 nm (green to red) based on AlP/GaP quarter-wave stacks are prepared on (001)GaP using gas-source molecular-beam epitaxy. Additionally, the complex refractive index of AlP is measured using spectroscopic ellipsometry within the range of 330-850 nm in order to facilitate an accurate reflector design. Structures consisting of 15 quarter-wave stacks reach a peak reflectance between 95% and 98%, depending on the spectral position of the maximum.

Emberger, Valentin; Hatami, Fariba; Ted Masselink, W. [Department of Physics, Humboldt-Universitaet zu Berlin, Newtonstrasse 15, D-12489 Berlin (Germany); Peters, Sven [Sentech Instruments GmbH, Schwarzschildstr. 2, 12489 Berlin (Germany)

2013-07-15T23:59:59.000Z

468

Light incoherence theory revisited by Heisenberg time-energy uncertainty challenges solar cell optimization  

E-Print Network [OSTI]

Optimization of the efficiency of solar cells is a major challenge for renewable energies. Using a rigorous theoretical approach, we show that the photocurrent generated in a solar cell depends strongly on the degree of coherence of the incident light. In accordance with Heisenberg uncertainty time-energy, incoherent light at photons of carrier energy lower than the active material bandgap can be absorbed whereas coherent light at the same carrier energy cannot. We identify cases where incoherence does enhance efficiency. This result has a dramatical impact on the way solar cells must be optimized regarding sunlight. As an illustration, surface-corrugated GaAs and c-Si thin-film solar cells are considered.

Herman, Aline; Deparis, Olivier

2014-01-01T23:59:59.000Z

469

III-nitride nanowires : novel materials for solid-state lighting.  

SciTech Connect (OSTI)

Although planar heterostructures dominate current solid-state lighting architectures (SSL), 1D nanowires have distinct and advantageous properties that may eventually enable higher efficiency, longer wavelength, and cheaper devices. However, in order to fully realize the potential of nanowire-based SSL, several challenges exist in the areas of controlled nanowire synthesis, nanowire device integration, and understanding and controlling the nanowire electrical, optical, and thermal properties. Here recent results are reported regarding the aligned growth of GaN and III-nitride core-shell nanowires, along with extensive results providing insights into the nanowire properties obtained using cutting-edge structural, electrical, thermal, and optical nanocharacterization techniques. A new top-down fabrication method for fabricating periodic arrays of GaN nanorods and subsequent nanorod LED fabrication is also presented.

Wang, George T.; Upadhya, Prashanth C. (Los Alamos National Laboratory, Los Alamos, NM); Prasankumar, Rohit P. (Los Alamos National Laboratory, Los Alamos, NM); Armstrong, Andrew M.; Huang, Jian Yu; Li, Qiming; Talin, Albert Alec (NIST, Gaithersburg, MD)

2010-12-01T23:59:59.000Z

470

Utility lighting summit proves illuminating  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Utility-lighting-summit-proves-illuminating Sign In About | Careers | Contact | Investors | bpa.gov Search News & Us Expand News & Us Projects & Initiatives Expand Projects...

471

Linac Coherent Light Source Overview  

ScienceCinema (OSTI)

Take an animated tour of the Linac Coherent Light Source (LCLS). Follow the laser pulse from the injector gun all the way through to the Far Experimental Hall.

None

2013-05-29T23:59:59.000Z

472

Light Water Reactor Sustainability Newsletter  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

and nuclear waste disposal. Dr. Corradini has extensive research experience in the phenomenology of beyond design basis Meet the New LWRS Program Pathway Lead accidents in light...

473

LED Lighting Off the Grid  

Energy Savers [EERE]

D. & Kammen, D. M. Decentralized energy systems for clean electricity access. Nature Climate Change accepted, in press, (2015). Off-Grid Status Quo : Fuel Based Lighting...

474

Pedestrian-Friendly Nighttime Lighting  

Broader source: Energy.gov [DOE]

This November 19, 2013 webinar presented issues and considerations related to pedestrian-friendly nighttime lighting, such as color rendering, safety, and adaptation. When it comes to outdoor...

475

Light Water Reactor Sustainability Newsletter  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

hydraulics software RELAP-7 (which is under development in the Light Water Reactor Sustainability LWRS Program). A novel interaction between the probabilistic part (i.e., RAVEN)...

476

Light Water Reactor Sustainability Newsletter  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

30-35, August 2012. Clayton, D. A. and M. S. Hileman, 2012, Light Water Reactor Sustainability Non-Destructive Evaluation for Concrete Research and Development Roadmap, ORNLTM-...

477

Linac Coherent Light Source Overview  

Broader source: Energy.gov [DOE]

Take an animated tour of the Linac Coherent Light Source (LCLS). Follow the laser pulse from the injector gun all the way through to the Far Experimental Hall.

478

Lighting with Paint FABIO PELLACINI  

E-Print Network [OSTI]

Lighting with Paint FABIO PELLACINI Dartmouth College and FRANK BATTAGLIA, R. KEITH MORLEY, animation, rendering, optimization, painting ACM Reference Format: Pellacini, F., Battaglia, F., Morley, R

Pellacini, Fabio

479

Corrosion-induced degradation of GaAs PHEMTs under operation in high humidity conditions  

E-Print Network [OSTI]

We have comprehensively investigated the degradation mechanism of AlGaAs/InGaAs pseudomorphic high-electron-mobility transistors (PHEMTs) under operation in high humidity conditions. PHEMTs degradation under high humidity ...

Hisaka, Takayuki

480

Electric field engineering in GaN high electron mobility transistors  

E-Print Network [OSTI]

In the last few years, AlGaN/GaN high electron mobility transistors (HEMTs) have become the top choice for power amplification at frequencies up to 20 GHz. Great interest currently exists in industry and academia to increase ...

Zhao, Xu, S.M. Massachusetts Institute of Technology

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "light comm ga" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

Site-controlled fabrication of Ga nanodroplets by focused ion beam  

SciTech Connect (OSTI)

Ga droplets are created by focused ion beam irradiation of GaAs surface. We report that ordered Ga droplets can be formed on the GaAs surface without any implantation damage. The droplets are characterized with bigger sizes than those droplets formed on damaged area. These aligned Ga droplets are formed via the migration of Ga atoms from ion irradiation area to the edge of undamaged GaAs surface and further nucleation into droplets. The morphological evolution and size distribution of these nanodroplets are investigated systematically with different beam irradiation time and incident angles. Based on this method, well positioned Ga nanodroplets, such as chains, are achieved by using focus ion beam patterning. The controllable assembly of droplets on undamaged semiconductor surface can be used to fabricate templates, to fabricate quantum structures and quantum devices by droplet epitaxy technique.

Xu, Xingliang; Wang, Zhiming M., E-mail: zhmwang@gmail.com [State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083 (China); Wu, Jiang; Li, Handong; Zhou, Zhihua [State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Wang, Xiaodong [Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083 (China)

2014-03-31T23:59:59.000Z

482

Device-level thermal analysis of GaN-based electronics  

E-Print Network [OSTI]

Gallium nitride (GaN)-based microelectronics are one of the most exciting semiconductor technologies for high power density and high frequency electronics. The excellent electrical properties of GaN and its related alloys ...

Bagnall, Kevin Robert

2013-01-01T23:59:59.000Z