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1

Molecular beam epitaxy of SrTiO3 with a growth window  

E-Print Network (OSTI)

Materials Fundamentals of Molecular Beam Epitaxy (AcademicMolecular beam epitaxy of SrTiO 3 with a growth windowgrowth window in conventional molecular beam epitaxy (MBE)

Stemmer, Susanne

2009-01-01T23:59:59.000Z

2

Photoluminescence study of GaAs films on Si(100) grown by atomic hydrogen-assisted molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Keywords: atomic hydrogen-mediated epitaxy, lattice-mismatched heteroepitaxy, minority carrier lifetime, molecular beam epitaxy, photoluminescence decay, solar cells

Yoshitaka Okada; Shigeru Ohta; Akio Kawabata; Hirofumi Shimomura; Mitsuo Kawabe

1994-03-01T23:59:59.000Z

3

Method of deposition by molecular beam epitaxy  

DOE Patents (OSTI)

A method is described for reproducibly controlling layer thickness and varying layer composition in an MBE deposition process. In particular, the present invention includes epitaxially depositing a plurality of layers of material on a substrate with a plurality of growth cycles whereby the average of the instantaneous growth rates for each growth cycle and from one growth cycle to the next remains substantially constant as a function of time.

Chalmers, Scott A. (Albuquerque, NM); Killeen, Kevin P. (Albuquerque, NM); Lear, Kevin L. (Albuquerque, NM)

1995-01-01T23:59:59.000Z

4

Si(001):B gas-source molecular-beam epitaxy: Boron surface segregation and its effect on film growth kinetics  

E-Print Network (OSTI)

The use of disilane (Si2H6) rather than silane (SiH4) for Si 001 gas-source molecular-beam epitaxy GS

Spila, Timothy P.

5

Fabrication of precision high quality facets on molecular beam epitaxy material  

DOE Patents (OSTI)

Fabricating mirrored vertical surfaces on semiconductor layered material grown by molecular beam epitaxy (MBE). Low energy chemically assisted ion beam etching (CAIBE) is employed to prepare mirrored vertical surfaces on MBE-grown III-V materials under unusually low concentrations of oxygen in evacuated etching atmospheres of chlorine and xenon ion beams. UV-stabilized smooth-surfaced photoresist materials contribute to highly vertical, high quality mirrored surfaces during the etching.

Petersen, Holly E. (Tracy, CA); Goward, William D. (Antioch, CA); Dijaili, Sol P. (Moraga, CA)

2001-01-01T23:59:59.000Z

6

Deposition of hetero-epitaxial In{sub 2}O{sub 3} thin films by molecular beam epitaxy  

SciTech Connect

Highly oriented thin film In{sub 2}O{sub 3} was heteroepitaxially grown on optically polished (100) plane of single crystalline yttria stabilized zirconia (YSZ) substrate using Molecular Beam Epitaxy (MBE). Full-width at half-maximum (FWHM) of X-ray rocking-curve showed 0.08{degree} for In{sub 2}O{sub 3} 200 nm thick layers indicating that excellent uniformity orientation compared with the heteroepitaxially-grown In{sub 2}O{sub 3} epitaxially deposited by the conventional methods such as electron-beam (e-beam) evaporation or sputtering method. The minimum yield ({chi}{sub min}) of the MBE grown in In{sub 2}O{sub 3} film of Rutherford Backscattering Spectrometry (RBS) was also extremely small value 3.1%, implying the very high crystallinity.

Taga, N.; Maekawa, M. [Asahi Glass Co., Ltd., Yokohama (Japan). Research Center; Shigesato, Y.; Yasui, I. [Univ. of Tokyo (Japan). Inst. of Industrial Science; Haynes, T.E. [Oak Ridge National Lab., TN (United States). Solid State Div.

1996-05-01T23:59:59.000Z

7

Molecular beam epitaxy passivation studies of Ge and III-V semiconductors for advanced CMOS  

Science Conference Proceedings (OSTI)

Future CMOS technologies will require the use of substrate material with a very high mobility in order to fulfil the performance requirements. Therefore, combination of Ge p-MOS with n-MOS devices made out of high mobility III/V compounds, such as GaAs, ... Keywords: High mobility semiconductors, Molecular beam epitaxy (MBE), Passivation

C. Merckling; J. Penaud; D. Kohen; F. Bellenger; A. Alian; G. Brammertz; M. El-Kazzi; M. Houssa; J. Dekoster; M. Caymax; M. Meuris; M. M. Heyns

2009-07-01T23:59:59.000Z

8

Low-temperature grown graphene films by using molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Complete graphene film is prepared by depositing carbon atoms directly on Cu foils in a molecular beam epitaxy chamber at 300 Degree-Sign C. The Raman spectrum of the film has indicated that high-quality few-layer graphene is obtained. With back-gated transistor architecture, the characteristic current modulation of graphene transistors is observed. Following the similar growth procedure, graphitization is observed at room temperature, which is consistent with the molecular dynamics simulations of graphene growth.

Lin, Meng-Yu [Institute of Electronics, National Taiwan University, Taipei, Taiwan (China); Research Center for Applied Sciences, Academia Sinica, Nankang, Taipei, Taiwan (China); Guo, Wei-Ching; Wang, Pro-Yao [Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung, Taiwan (China); Wu, Meng-Hsun [College of Photonics, National Chiao-Tung University, Tainan, Taiwan (China); Liu, Te-Huan; Chang, Chien-Cheng [Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan (China); Pao, Chun-Wei; Lin, Shih-Yen [Research Center for Applied Sciences, Academia Sinica, Nankang, Taipei, Taiwan (China); Lee, Si-Chen [Institute of Electronics, National Taiwan University, Taipei, Taiwan (China)

2012-11-26T23:59:59.000Z

9

Site-controlled Ag nanocrystals grown by molecular beam epitaxy-Towards plasmonic integration technology  

Science Conference Proceedings (OSTI)

We demonstrate site-controlled growth of epitaxial Ag nanocrystals on patterned GaAs substrates by molecular beam epitaxy with high degree of long-range uniformity. The alignment is based on lithographically defined holes in which position controlled InAs quantum dots are grown. The Ag nanocrystals self-align preferentially on top of the InAs quantum dots. No such ordering is observed in the absence of InAs quantum dots, proving that the ordering is strain-driven. The presented technique facilitates the placement of active plasmonic nanostructures at arbitrarily defined positions enabling their integration into complex devices and plasmonic circuits.

Urbanczyk, Adam [COBRA Research Institute on Communication Technology, Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Noetzel, Richard [Institute for Systems based on Optoelectronics and Microtechnology (ISOM), ETSI Telecommunication, Technical University of Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)

2012-12-15T23:59:59.000Z

10

Reflection mass spectrometry technique for monitoring and controlling composition during molecular beam epitaxy  

DOE Patents (OSTI)

This invention is comprised of a method for on-line accurate monitoring and precise control of molecular beam epitaxial growth of Groups III-III-V or Groups III-V-V layers in an advanced semiconductor device incorporates reflection mass spectrometry. The reflection mass spectrometry is responsive to intentional perturbations in molecular fluxes incident on a substrate by accurately measuring the molecular fluxes reflected from the substrate. The reflected flux is extremely sensitive to the state of the growing surface and the measurements obtained enable control of newly forming surfaces that are dynamically changing as a result of growth.

Brennan, T.M.; Hammons, B.E.; Tsao, J.Y.

1990-08-15T23:59:59.000Z

11

Reflection mass spectrometry technique for monitoring and controlling composition during molecular beam epitaxy  

DOE Patents (OSTI)

A method for on-line accurate monitoring and precise control of molecular beam epitaxial growth of Groups III-III-V or Groups III-V-V layers in an advanced semiconductor device incorporates reflection mass spectrometry. The reflection mass spectrometry is responsive to intentional perturbations in molecular fluxes incident on a substrate by accurately measuring the molecular fluxes reflected from the substrate. The reflected flux is extremely sensitive to the state of the growing surface and the measurements obtained enable control of newly forming surfaces that are dynamically changing as a result of growth.

Brennan, Thomas M. (Albuquerque, NM); Hammons, B. Eugene (Tijeras, NM); Tsao, Jeffrey Y. (Albuquerque, NM)

1992-01-01T23:59:59.000Z

12

The control of size and areal density of InAs self-assembled quantum dots in selective area molecular beam epitaxy on GaAs (001) surface  

Science Conference Proceedings (OSTI)

The growth of InAs quantum dots (QDs) on GaAs (001) substrates by selective area molecular beam epitaxy (SA-MBE) with dielectric mask is investigated. The GaAs polycrystals on the mask, which is formed during growth due to low GaAs selectivity between ... Keywords: InAs quantum dots, Molecular beam epitaxy, Selective area epitaxy

J. C. Lin; P. W. Fry; R. A. Hogg; M. Hopkinson; I. M. Ross; A. G. Cullis; R. S. Kolodka; A. I. Tartakovskii; M. S. Skolnick

2006-12-01T23:59:59.000Z

13

High-quality epitaxial CoFe/Si(111) heterostructures fabricated by low-temperature molecular beam epitaxy  

SciTech Connect

We demonstrate atomically controlled heterojunctions consisting of ferromagnetic CoFe alloys and silicon (Si) using low-temperature molecular beam epitaxy with a good atomic matching at the (111) plane. The saturation magnetization of the CoFe layers grown reaches {approx}85% of the value of bulk samples reported so far, and can be systematically controlled by tuning the ratio of Co to Fe, indicating that the silicidation reactions between CoFe and Si are suppressed and the heterojunctions are very high quality. We find that the Schottky barrier height of the high-quality CoFe/Si(111) junctions is unexpectedly low compared to the previous data for other metal/Si ones, implying the reduction in the Fermi-level-pinning effect. We can expand the available high-quality ferromagnet/Si heterostructures in the field of Si-based spintronics.

Maeda, Y.; Yamada, S.; Ando, Y.; Yamane, K.; Miyao, M. [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Hamaya, K. [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); PRESTO, Japan Science and Technology Agency, Sanbancho, Tokyo 102-0075 (Japan)

2010-11-08T23:59:59.000Z

14

Demonstration of molecular beam epitaxy and a semiconducting band structure for I-Mn-V compounds  

SciTech Connect

Our ab initio theory calculations predict a semiconducting band structure of I-Mn-V compounds. We demonstrate on LiMnAs that high-quality materials with group-I alkali metals in the crystal structure can be grown by molecular beam epitaxy. Optical measurements on the LiMnAs epilayers are consistent with the theoretical electronic structure. Our calculations also reproduce earlier reports of high antiferromagnetic ordering temperature and predict large, spin-orbit-coupling-induced magnetic anisotropy effects. We propose a strategy for employing antiferromagnetic semiconductors in high-temperature semiconductor spintronics.

Jungwirth, T. [Institute of Physics ASCR, v.v.i., Cukrovarnicka 10, 162 53 Praha 6 (Czech Republic); School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Novak, V.; Cukr, M.; Zemek, J. [Institute of Physics ASCR, v.v.i., Cukrovarnicka 10, 162 53 Praha 6 (Czech Republic); Marti, X.; Horodyska, P.; Nemec, P.; Holy, V. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2 (Czech Republic); Maca, F.; Shick, A. B.; Masek, J.; Kuzel, P. [Institute of Physics ASCR, v.v.i., Na Slovance 2, 182 21 Praha 8 (Czech Republic); Nemec, I. [Faculty of Science, Charles University in Prague, Hlavova 2030, 128 40 Prague 2 (Czech Republic); Gallagher, B. L.; Campion, R. P.; Foxon, C. T. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Wunderlich, J. [Institute of Physics ASCR, v.v.i., Cukrovarnicka 10, 162 53 Praha 6 (Czech Republic); Hitachi Cambridge Laboratory, Cambridge CB3 0HE (United Kingdom)

2011-01-15T23:59:59.000Z

15

Graphene growth by molecular beam epitaxy on the carbon-face of SiC  

SciTech Connect

Graphene layers have been grown by molecular beam epitaxy (MBE) on the (0001) C-face of SiC and have been characterized by atomic force microscopy, low energy electron diffraction (LEED), and UV photoelectron spectroscopy. Contrary to the graphitization process, the step-terrace structure of SiC is fully preserved during the MBE growth. LEED patterns show multiple orientation domains which are characteristic of graphene on SiC (0001), indicating non-Bernal rotated graphene planes. Well-defined Dirac cones, typical of single-layer graphene, have been observed in the valence band for few graphene layers by synchrotron spectroscopy, confirming the electronic decoupling of graphene layers.

Moreau, E.; Godey, S.; Ferrer, F. J.; Vignaud, D.; Wallart, X. [IEMN, UMR CNRS 8520, Avenue Poincare, P.O. Box 60069, 59652 Villeneuve d'Ascq Cedex (France); Avila, J.; Asensio, M. C. [Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin-BP 48, 91192 Gif sur Yvette Cedex (France); Bournel, F.; Gallet, J.-J. [LCPM, Universite Pierre et Marie Curie, UMR CNRS 7614, 75231 Paris Cedex (France)

2010-12-13T23:59:59.000Z

16

A portable molecular beam epitaxy system for in situ x-ray investigations at synchrotron beamlines  

SciTech Connect

A portable synchrotron molecular beam epitaxy (MBE) system is designed and applied for in situ investigations. The growth chamber is equipped with all the standard MBE components such as effusion cells with shutters, main shutter, cooling shroud, manipulator, reflection high energy electron diffraction setup, and pressure gauges. The characteristic feature of the system is the beryllium windows which are used for in situ x-ray measurements. An UHV sample transfer case allows in vacuo transfer of samples prepared elsewhere. We describe the system design and demonstrate its performance by investigating the annealing process of buried InGaAs self-organized quantum dots.

Slobodskyy, T. [Institute for Synchrotron Radiation, Karlsruhe Institute of Technology - 76344 Eggenstein-Leopoldshafen (Germany); Institut fuer Angewandte Physik und Zentrum fuer Mikrostrukturforschung, Jungiusstrasse 11, D-20355 Hamburg (Germany); Schroth, P.; Grigoriev, D.; Minkevich, A. A.; Baumbach, T. [Institute for Synchrotron Radiation, Karlsruhe Institute of Technology - 76344 Eggenstein-Leopoldshafen (Germany); Hu, D. Z.; Schaadt, D. M. [Institute for Applied Physics/DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Institute for Energy Research and Physical Technologies, Technical University Clausthal, Am Stollen 19B, 38640 Goslar (Germany)

2012-10-15T23:59:59.000Z

17

Electrical properties and interfacial chemical environments of in situ atomic layer deposited Al2O3 on freshly molecular beam epitaxy grown GaAs  

Science Conference Proceedings (OSTI)

Interfacial chemical analyses and electrical characterization of in situ atomic layer deposited (ALD) Al"2O"3 on freshly molecular beam epitaxy (MBE) grown n- and p- GaAs (001) with a (4x6) surface reconstruction are performed. The capacitance-voltage ... Keywords: Atomic layer deposition, III-V compound semiconductor, Molecular beam epitaxy

Y. H. Chang; M. L. Huang; P. Chang; C. A. Lin; Y. J. Chu; B. R. Chen; C. L. Hsu; J. Kwo; T. W. Pi; M. Hong

2011-04-01T23:59:59.000Z

18

Epitaxial growth of MgO and Fe/MgO/Fe magnetic tunnel junctions on (100)-Si by molecular beam epitaxy  

SciTech Connect

Epitaxial growth of MgO barrier on Si is of technological importance due to the symmetry filtering effect of the MgO barrier in conjunction with bcc-ferromagnets. We study the epitaxial growth of MgO on (100)-Si by molecular beam epitaxy. MgO matches Si with 4:3 cell ratio, which renders Fe to be 45 deg. rotated relative to Si, in sharp contrast to the direct epitaxial growth of Fe on Si. The compressive strains from Si lead to the formation of small angle grain boundaries in MgO below 5 nm, and also affect the transport characteristics of Fe/MgO/Fe magnetic tunnel junctions formed on top.

Miao, G. X.; Veenhuizen, M. J. van; Moodera, J. S. [Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Chang, J. Y. [Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Center for Spintronics Research, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Thiel, K.; Seibt, M.; Eilers, G.; Muenzenberg, M. [IV.Physikalisches Institut, Universitaet Goettingen, Goettingen 37073 (Germany)

2008-10-06T23:59:59.000Z

19

Growth of p-type and n-type m-plane GaN by molecular beam epitaxy  

E-Print Network (OSTI)

cm ?3 corresponding to p-type ?lm conductivi- ties as highOF APPLIED PHYSICS 100, 063707 ?2006? Growth of p-type andn-type m-plane GaN by molecular beam epitaxy M. McLaurin, a?

McLaurin, M; Mates, T E; Wu, F; Speck, J S

2006-01-01T23:59:59.000Z

20

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

SciTech Connect

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

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

Molecular beam epitaxy of SrTiO{sub 3} with a growth window  

Science Conference Proceedings (OSTI)

Many complex oxides with only nonvolatile constituents do not have a wide growth window in conventional molecular beam epitaxy (MBE) approaches, which makes it difficult to obtain stoichiometric films. Here it is shown that a growth window in which the stoichiometry is self-regulating can be achieved for SrTiO{sub 3} films by using a hybrid MBE approach that uses a volatile metal-organic source for Ti, titanium tetra isopropoxide (TTIP). The growth window widens and shifts to higher TTIP/Sr flux ratios with increasing temperature, showing that it is related to the desorption of the volatile TTIP. We demonstrate stoichiometric, highly perfect, insulating SrTiO{sub 3} films. The approach can be adapted for the growth of other complex oxides that previously were believed to have no wide MBE growth window.

Jalan, Bharat; Moetakef, Pouya; Stemmer, Susanne [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)

2009-07-20T23:59:59.000Z

22

Fe-doped InN layers grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Iron(Fe)-doped InN (InN:Fe) layers have been grown by molecular beam epitaxy. It is found that Fe-doping leads to drastic increase of residual electron concentration, which is different from the semi-insulating property of Fe-doped GaN. However, this heavy n-type doping cannot be fully explained by doped Fe-concentration ([Fe]). Further analysis shows that more unintentionally doped impurities such as hydrogen and oxygen are incorporated with increasing [Fe] and the surface is degraded with high density pits, which probably are the main reasons for electron generation and mobility reduction. Photoluminescence of InN is gradually quenched by Fe-doping. This work shows that Fe-doping is one of good choices to control electron density in InN.

Wang Xinqiang; Liu Shitao; Ma Dingyu; Zheng Xiantong; Chen Guang; Xu Fujun; Tang Ning; Shen Bo [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Zhang Peng; Cao Xingzhong; Wang Baoyi [State Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Huang Sen; Chen, Kevin J. [Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology (Hong Kong); Zhou Shengqiang [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01314 Dresden (Germany); Yoshikawa, Akihiko [Center for SMART Green Innovation Research, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan)

2012-10-22T23:59:59.000Z

23

High electron mobility in Ga(In)NAs films grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

We report the highest mobility values above 2000 cm{sup 2}/Vs in Si doped GaNAs film grown by molecular beam epitaxy. To understand the feature of the origin which limits the electron mobility in GaNAs, temperature dependences of mobility were measured for high mobility GaNAs and referential low mobility GaInNAs. Temperature dependent mobility for high mobility GaNAs is similar to the GaAs case, while that for low mobility GaInNAs shows large decrease in lower temperature region. The electron mobility of high quality GaNAs can be explained by intrinsic limiting factor of random alloy scattering and extrinsic factor of ionized impurity scattering.

Miyashita, Naoya; Ahsan, Nazmul; Monirul Islam, Muhammad; Okada, Yoshitaka [Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Inagaki, Makoto [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku-ku, Nagoya 468-8511, Aichi (Japan); Yamaguchi, Masafumi [Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Toyota Technological Institute, 2-12-1 Hisakata, Tempaku-ku, Nagoya 468-8511, Aichi (Japan)

2012-11-26T23:59:59.000Z

24

Mechanism of Charge Transport in Cobalt and Iron Phthalocyanine Thin Films Grown by Molecular Beam Epitaxy  

Science Conference Proceedings (OSTI)

Cobalt phthalocyanine (CoPc), iron phthalocyanine (FePc) and their composite (CoPc-FePc) films have been grown by molecular beam epitaxy (MBE). Grazing incidence X-ray diffraction (GIXRD) and scanning electron microscope (SEM) studies showed that composite films has better structural ordering compared to individual CoPc and FePc films. The temperature dependence of resistivity (in the temperature range 25 K- 100 K) showed that composite films are metallic, while individual CoPc and FePc films are in the critical regime of metal-to-insulator (M-I) transition The composite films show very high mobility of 110 cm{sup 2} V{sup -1} s{sup -1} at room temperature i.e. nearly two order of magnitude higher compared to pure CoPc and FePc films.

Kumar, Arvind; Samanta, Soumen; Singh, Ajay; Debnath, A. K.; Aswal, D. K.; Gupta, S. K. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

2011-12-12T23:59:59.000Z

25

NO-assisted molecular-beam epitaxial growth of nitrogen substituted EuO  

Science Conference Proceedings (OSTI)

We have investigated a method for substituting oxygen with nitrogen in EuO thin films, which is based on molecular beam epitaxy distillation with NO gas as the oxidizer. By varying the NO gas pressure, we produce crystalline, epitaxial EuO{sub 1-x}N{sub x} films with good control over the films' nitrogen concentration. In situ x-ray photoemission spectroscopy reveals that nitrogen substitution is connected to the formation Eu{sup 3+}4f{sup 6} and a corresponding decrease in the number of Eu{sup 2+}4f{sup 7}, indicating that nitrogen is being incorporated in its 3{sup -} oxidation state. While small amounts of Eu{sup 3+} in over-oxidized Eu{sub 1-{delta}}O thin films lead to a drastic suppression of the ferromagnetism, the formation of Eu{sup 3+} in EuO{sub 1-x}N{sub x} still allows the ferromagnetic phase to exist with an unaffected T{sub c}, thus providing an ideal model system to study the interplay between the magnetic f{sup 7} (J = 7/2) and the non-magnetic f{sup 6} (J = 0) states close to the Fermi level.

Wicks, R. [Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1 (Canada); Altendorf, S. G.; Caspers, C.; Kierspel, H.; Sutarto, R. [II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany); Tjeng, L. H. [II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany); Max Planck Institute for Chemical Physics of Solids, 01187 Dresden (Germany); Damascelli, A. [Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1 (Canada); Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4 (Canada)

2012-04-16T23:59:59.000Z

26

Ultra-low resistance ohmic contacts to GaN with high Si doping concentrations grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Ti/Al/Ni/Au ohmic contacts were formed on heavily doped n{sup +} metal-polar GaN samples with various Si doping concentrations grown by molecular beam epitaxy. The contact resistivity (R{sub C}) and sheet resistance (R{sub sh}) as a function of corresponding GaN free carrier concentration (n) were measured. Very low R{sub C} values (electron mobility transistors.

Afroz Faria, Faiza; Guo Jia; Zhao Pei; Li Guowang; Kumar Kandaswamy, Prem; Wistey, Mark; Xing Huili; Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)

2012-07-16T23:59:59.000Z

27

Usage of antimony segregation for selective doping of Si in molecular beam epitaxy  

SciTech Connect

An original approach to selective doping of Si by antimony (Sb) in molecular beam epitaxy (MBE) is proposed and verified experimentally. This approach is based on controllable utilization of the effect of Sb segregation. In particular, the sharp dependence of Sb segregation on growth temperature in the range of 300-550 deg. C is exploited. The growth temperature variations between the kinetically limited and maximum segregation regimes are suggested to be utilized in order to obtain selectively doped structures with abrupt doping profiles. It is demonstrated that the proposed technique allows formation of selectively doped Si:Sb layers, including delta ({delta}-)doped layers in which Sb concentrations can be varied from 5 x 10{sup 15} to 10{sup 20} cm{sup -3}. The obtained doped structures are shown to have a high crystalline quality and the short-term growth interruptions, which are needed to change the substrate temperature, do not lead to any significant accumulation of background impurities in grown samples. Realization of the proposed approach requires neither too low (<300 deg. C), nor too high (>600 deg. C) growth temperatures or any special equipment for the MBE machines.

Yurasov, D. V.; Drozdov, M. N.; Murel, A. V.; Shaleev, M. V.; Novikov, A. V. [Institute for Physics of Microstructures Russian Academy of Sciences, 603950, Nizhny Novgorod, GSP-105 (Russian Federation); Zakharov, N. D. [Max-Planck-Institut fur Mikrostrukturphysik, Weinberg 2, 06120 Halle/Saale (Germany)

2011-06-01T23:59:59.000Z

28

Lattice-registered growth of GaSb on Si (211) with molecular beam epitaxy  

Science Conference Proceedings (OSTI)

A GaSb film was grown on a Si(211) substrate using molecular beam epitaxy indicating full lattice relaxation as well as full lattice registration and dislocation-free growth in the plane perpendicular to the [01 - 1]-direction. Heteroepitaxy of GaSb on a Si(211) substrate is dominated by numerous first order and multiple higher order micro-twins. The atomic-resolved structural study of GaSb films by high-angle annular dark-field scanning transmission electron microscopy reveals that slight tilt, along with twinning, favors the lattice registry to Si(211) substrates. Preferential bonding of impinging Ga and Sb atoms at the interface due to two distinctive bonding sites on the Si(211) surface enables growth that is sublattice-ordered and free of anti-phase boundaries. The role of the substrate orientation on the strain distribution of GaSb epilayers is further elucidated by investigating the local change in the lattice parameter using the geometric phase analysis method and hence effectiveness of the lattice tilting in reducing the interfacial strain was confirmed further.

Hosseini Vajargah, S.; Botton, G. A. [Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Canadian Centre for Electron Microscopy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Ghanad-Tavakoli, S. [Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Preston, J. S.; Kleiman, R. N. [Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Department of Engineering Physics, McMaster University, Hamilton, Ontario L8S 4L7 (Canada)

2012-11-01T23:59:59.000Z

29

High temperature step-flow growth of gallium phosphide by molecular beam epitaxy and metalorganic chemical vapor deposition  

Science Conference Proceedings (OSTI)

Post-growth surface morphologies of high-temperature homoepitaxial GaP films grown by molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) have been studied. Smooth, stepped surface morphologies of MBE-grown layers, measured by atomic force microscopy, were found for a wide range of substrate temperatures and P{sub 2}:Ga flux ratios. A MOCVD-based growth study performed under similar conditions to MBE-grown samples shows a nearly identical smooth, step-flow surface morphology, presenting a convergence of growth conditions for the two different methods. The additional understanding of GaP epitaxy gained from this study will impact its use in applications that include GaP-based device technologies, III-V metamorphic buffers, and III-V materials integration with silicon.

Ratcliff, C. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Grassman, T. J.; Ringel, S. A. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Institute for Materials Research, Ohio State University, Columbus, Ohio 43210 (United States); Carlin, J. A. [Institute for Materials Research, Ohio State University, Columbus, Ohio 43210 (United States)

2011-10-03T23:59:59.000Z

30

Growth of AlN/SiC/AlN quantum wells on Si(111) by molecular beam epitaxy  

SciTech Connect

AlN/SiC/AlN quantum well structures have been grown on Si(111) by molecular beam epitaxy at 700 deg. C. The microstructure is single-crystal wurtzite AlN and cubic SiC with stacking sequence disorder. Depth profiles taken by Auger electron spectroscopy indicate that the ratio of Si to C is about 5:4. Layers with lower carbon content exhibit regions with five-fold superstructures. Fourier transform infrared spectroscopy confirms the presence of Al-N and Si-C bonds. Our work demonstrates the feasibility of a low-temperature synthesis route for epitaxial SiC and AlN/SiC heterostructures on Si.

Cheng Yana [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); Beresford, Roderic [School of Engineering, Brown University, Providence, Rhode Island 02912 (United States)

2012-06-04T23:59:59.000Z

31

Surface morphologies of homoepitaxial ZnO on Zn- and O-polar substrates by plasma assisted molecular beam epitaxy  

SciTech Connect

Homoepitaxial ZnO layers are grown on Zn-polar (0001) and O-polar (0001) surfaces of single crystal ZnO substrates by plasma assisted molecular beam epitaxy. It is found that the growth conditions to obtain smooth surfaces are significantly different for the two surface polarities. For growth on Zn-polar surface, moderate temperature (650 deg. C) and highly O-rich condition (low Zn/O{sub 2}) are required, while high temperature (1000-1050 deg. C) and Zn-rich condition (high Zn/O{sub 2} ratio) are essential for growth on O-polar surfaces.

Xu Huaizhe; Ohtani, K.; Yamao, M.; Ohno, H. [Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2006-08-14T23:59:59.000Z

32

Insights in High-Temperature Superconductivity from the Study of Films and Heterostructures Synthesized by Molecular Beam Epitaxy  

Science Conference Proceedings (OSTI)

Using molecular beam epitaxy, we synthesize atomically smooth thin films, multilayers and superlattices of cuprate high-temperature superconductors (HTS). Such heterostructures enable novel experiments that probe the basicphysics of HTS. For example, we have established that HTS and antiferromagnetic phases separate on ngstrom scale, while the pseudo-gap state apparently mixes with HTS over an anomalously large length scale ('Giant Proximity Effect'). Here, we briefly review our most recent experiments on such films and superlattices. The new results include an unambiguous demonstration of strong coupling of in-plane charge excitations to out-of-plane lattice vibrations and the discovery of interface HTS.

Bozovic,I.

2009-01-09T23:59:59.000Z

33

Molecular-beam epitaxy and robust superconductivity of stoichiometric FeSe crystalline films on bilayer graphene  

Science Conference Proceedings (OSTI)

We report on molecular beam epitaxy growth of stoichiometric and superconducting FeSe crystalline thin films on double-layer graphene. Layer-by-layer growth of high-quality films has been achieved in a well-controlled manner by using Se-rich condition, which allow us to investigate the thickness-dependent superconductivity of FeSe. In situ low-temperature scanning tunneling spectra reveal that the local superconducting gap in the quasiparticle density of states is visible down to two triple layers for the minimum measurement temperature of 2.2 K, and that the transition temperature T{sub c} scales inversely with film thickness.

Song Canli; Jiang Yeping; Xue Qikun [State Key Laboratory for Surface Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); State Key Laboratory for Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084 (China); Wang Yilin; Li Zhi; Wang Lili; He Ke; Ma Xucun [State Key Laboratory for Surface Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Chen Xi [State Key Laboratory for Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084 (China)

2011-07-01T23:59:59.000Z

34

Growth of SrTiO{sub 3}(110) film by oxide molecular beam epitaxy with feedback control  

SciTech Connect

By controlling the growth of complex oxide films with atomic precision, emergent phenomena and fascinating properties have been discovered, and even been manipulated. With oxide molecular beam epitaxy (OMBE) we grow high-quality SrTiO{sub 3}(110) films by evaporating Sr and Ti metals with separate controls of the open/close timing of the shutters. The incident electron beam angle of the reflective high energy electron diffraction (RHEED) is adjusted to make the (01) beam sensitive to surface chemical concentration. By monitoring such an intensity, we tune the shutter timing to synchronize the evaporation amount of Sr and Ti in real-time. The intensity is further used as a feedback control signal for automatic growth optimization to fully compensate the possible fluctuation of the source flux rates upon extended growth. A 22 nm-thick film is obtained with the precision of metal cation stoichiometry better than 0.5%.

Feng Jiagui; Yang Fang; Yang Yang; Gu Lin; Guo Jiandong [Beijing National Laboratory for Condensed-Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wang Zhiming [Beijing National Laboratory for Condensed-Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna (Austria); Zhang Jiandi [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70808 (United States)

2012-12-15T23:59:59.000Z

35

GaAs structures with InAs and As quantum dots produced in a single molecular beam epitaxy process  

Science Conference Proceedings (OSTI)

Epitaxial GaAs layers containing InAs semiconductor quantum dots and As metal quantum dots are grown by molecular beam epitaxy. The InAs quantum dots are formed by the Stranskii-Krastanow mechanism, whereas the As quantum dots are self-assembled in the GaAs layer grown at low temperature with a large As excess. The microstructure of the samples is studied by transmission electron microscopy. It is established that the As metal quantum dots formed in the immediate vicinity of the InAs semiconductor quantum dots are larger in size than the As quantum dots formed far from the InAs quantum dots. This is apparently due to the effect of strain fields of the InAs quantum dots upon the self-assembling of As quantum dots. Another phenomenon apparently associated with local strains around the InAs quantum dots is the formation of V-like defects (stacking faults) during the overgrowth of the InAs quantum dots with the GaAs layer by low-temperature molecular beam epitaxy. Such defects have a profound effect on the self-assembling of As quantum dots. Specifically, on high-temperature annealing needed for the formation of large-sized As quantum dots by Ostwald ripening, the V-like defects bring about the dissolution of the As quantum dots in the vicinity of the defects. In this case, excess arsenic most probably diffuses towards the open surface of the sample via the channels of accelerated diffusion in the planes of stacking faults.

Nevedomskii, V. N., E-mail: nevedom@mail.ioffe.ru; Bert, N. A.; Chaldyshev, V. V., E-mail: Chald@gvg.ioffe.ru [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Preobrazhenskii, V. V.; Putyato, M. A.; Semyagin, B. R. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Division (Russian Federation)

2009-12-15T23:59:59.000Z

36

Self-organized GaAs patterns on misoriented GaAs (111)B substrates using dilute nitrides by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Recently, the growth of patterned surfaces is being used to demonstrate the site control of the three-dimensional nanostructures, and in particular quantum dots. Nevertheless the pre-patterning techniques show some disadvantages. In this work, we report ... Keywords: Dilute nitrides, InAs, Molecular beam epitaxy, Patterned surface, Quantum dots

R. Gargallo; J. Miguel-Snchez; . Guzmn; U. Jahn; E. Muoz

2006-12-01T23:59:59.000Z

37

CdSe/CdTe type-II superlattices grown on GaSb (001) substrates by molecular beam epitaxy  

SciTech Connect

CdSe/CdTe superlattices are grown on GaSb substrates using molecular beam epitaxy. X-ray diffraction measurements and cross-sectional transmission electron microscopy images indicate high crystalline quality. Photoluminescence (PL) measurements show the effective bandgap varies with the superlattice layer thicknesses and confirm the CdSe/CdTe heterostructure has a type-II band edge alignment. The valence band offset between unstrained CdTe and CdSe is determined as 0.63 {+-} 0.06 eV by fitting the measured PL peak positions using the envelope function approximation and the Kronig-Penney model. These results suggest that CdSe/CdTe superlattices are promising candidates for multi-junction solar cells and other optoelectronic devices based on GaSb substrates.

Li Jingjing; Liu Shi; Wang Shumin; Ding Ding; Johnson, Shane R.; Zhang Yonghang [Center for Photonics Innovation, Arizona State University, Tempe, Arizona 85287 (United States); School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287 (United States); Liu Xinyu; Furdyna, Jacek K. [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Smith, David J. [Center for Photonics Innovation, Arizona State University, Tempe, Arizona 85287 (United States); Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States)

2012-03-19T23:59:59.000Z

38

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

SciTech Connect

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

39

Molecular beam epitaxy-grown wurtzite MgS thin films for solar-blind ultra-violet detection  

SciTech Connect

Molecular beam epitaxy grown MgS on GaAs(111)B substrate was resulted in wurtzite phase, as demonstrated by detailed structural characterizations. Phenomenological arguments were used to account for why wurtzite phase is preferred over zincblende phase or its most stable rocksalt phase. Results of photoresponse and reflectance measurements performed on wurtzite MgS photodiodes suggest a direct bandgap at around 5.1 eV. Their response peaks at 245 nm with quantum efficiency of 9.9% and enjoys rejection of more than three orders at 320 nm and close to five orders at longer wavelengths, proving the photodiodes highly competitive in solar-blind ultraviolet detection.

Lai, Y. H.; He, Q. L. [Nano Science and Nano Technology Program, The Hong Kong University of Science and Technology, HKSAR, People's Republic of China (China) [Nano Science and Nano Technology Program, The Hong Kong University of Science and Technology, HKSAR, People's Republic of China (China); Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, HKSAR, People's Republic of China (China); Cheung, W. Y.; Lok, S. K.; Wong, K. S.; Sou, I. K. [Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, HKSAR, People's Republic of China (China)] [Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, HKSAR, People's Republic of China (China); Ho, S. K. [Faculty of Science and Technology, University of Macau, Macau, People's Republic of China (China)] [Faculty of Science and Technology, University of Macau, Macau, People's Republic of China (China); Tam, K. W. [Department of Electrical and Electronics Engineering, University of Macau, Macau, People's Republic of China (China)] [Department of Electrical and Electronics Engineering, University of Macau, Macau, People's Republic of China (China)

2013-04-29T23:59:59.000Z

40

Effect of in-situ oxygen on the electronic properties of graphene grown by carbon molecular beam epitaxy grown  

Science Conference Proceedings (OSTI)

We report that graphene grown by molecular beam epitaxy from solid carbon (CMBE) on (0001) SiC in the presence of unintentional oxygen exhibits a small bandgap on the order of tens of meV. The presence of bandgaps is confirmed by temperature dependent Hall effect and resistivity measurements. X-ray photoelectron spectroscopy (XPS) measurements suggest that oxygen incorporates into the SiC substrate in the form of O-Si-C and not into the graphene as graphene oxide or some other species. The effect is independent of the carrier type of the graphene. Temperature dependent transport measurements show the presence of hopping conduction in the resistivity and a concurrent disappearance of the Hall voltage. Interactions between the graphene layers and the oxidized substrate are believed to be responsible for the bandgap.

Park, Jeongho; Mitchel, W. C.; Back, Tyson C. [Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXPS), Wright-Patterson AFB, Ohio 45433-7707 (United States); Elhamri, Said [Department of Physics, University of Dayton, Dayton, Ohio 45469 (United States)

2012-03-26T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" from the National Library of EnergyBeta (NLEBeta).
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41

Molecular beam epitaxy growth of PbSe on Si (211) using a ZnTe buffer layer  

Science Conference Proceedings (OSTI)

The authors report the results of successful growth of single crystalline PbSe on Si (211) substrates with ZnTe as a buffer layer by molecular beam epitaxy. Single crystalline PbSe with (511) orientation was achieved on ZnTe/Si (211), as evidenced by RHEED patterns indicative of 2 dimensional (2D) growth, x ray diffraction rocking curves with a full width at half maximum as low as 153 arc sec and mobility as large as 1.1x10{sup 4}cm{sup 2}V{sup -1}s{sup -1} at 77 K. Cross hatch patterns were found on the PbSe(511) surface in Nomarski filtered microscope images suggesting the presence of a surface thermal strain relaxation mechanism, which was confirmed by Fourier transformed high resolution transmission electron microscope images.

Wang, X. J.; Chang, Y.; Hou, Y. B.; Becker, C. R.; Kodama, R.; Aqariden, F.; Sivananthan, S. [Microphysics Laboratory, Physics Department, University of Illinois at Chicago, Illinois 60607 (United States); Microphysics Laboratory, Physics Department, University of Illinois at Chicago, Illinois 60607 and Physics Department and Quantum Functional Semiconductor Research Center, Dongguk University 3-26, Seoul 100-715 (Korea, Republic of); Microphysics Laboratory, Physics Department, University of Illinois at Chicago, Illinois 60607 (United States); EPIR Technologies, Bolingbrook, Illinois 60440 (United States); Microphysics Laboratory, Physics Department, University of Illinois at Chicago, Illinois 60607 and EPIR Technologies, Bolingbrook, Illinois 60440 (United States)

2011-09-15T23:59:59.000Z

42

Growth of high Bi concentration GaAs{sub 1-x}Bi{sub x} by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

The incorporation of Bi is investigated in the molecular beam epitaxy growth of GaAs{sub 1-x}Bi{sub x}. Bi content increases rapidly as the As{sub 2}:Ga flux ratio is lowered to 0.5 and then saturates for lower flux ratios. Growth under Ga and Bi rich conditions shows that Bi content increases strongly with decreasing temperature. A model is proposed where Bi from a wetting layer incorporates through attachment to Ga-terminated surface sites. The weak Ga-Bi bond can be broken thermally, ejecting Bi back into the wetting layer. Highly crystalline films with up to 22% Bi were grown at temperatures as low as 200 Degree-Sign C.

Lewis, R. B. [Department of Physics and Astronomy, University of British Columbia, V6T 1Z1 Vancouver (Canada); Department of Electrical and Computer Engineering, University of Victoria, V8W 3P6 Victoria (Canada); Masnadi-Shirazi, M. [Department of Electrical and Computer Engineering, University of Victoria, V8W 3P6 Victoria (Canada); Department of Electrical and Computer Engineering, University of British Columbia, V6T 1Z4 Vancouver (Canada); Tiedje, T. [Department of Electrical and Computer Engineering, University of Victoria, V8W 3P6 Victoria (Canada)

2012-08-20T23:59:59.000Z

43

Intrinsic ultrathin topological insulators grown via molecular beam epitaxy characterized by in-situ angle resolved photoemission spectroscopy  

Science Conference Proceedings (OSTI)

We demonstrate the capability of growing high quality ultrathin (10 or fewer quintuple layers) films of the topological insulators Bi{sub 2}Se{sub 3} and Bi{sub 2}Te{sub 3} using molecular beam epitaxy. Unlike previous growth techniques, which often pin the Fermi energy in the conduction band for ultrathin samples, our samples remain intrinsic bulk insulators. We characterize these films using in-situ angle resolved photoemission spectroscopy, which is a direct probe of bandstructure, and ex-situ atomic force microscopy. We find that the conduction band lies above the Fermi energy, indicating bulk insulating behavior with only the surface states crossing the Fermi energy. The use of a thermal cracker allows for more stoichiometric flux rates during growth, while still creating intrinsically doped films, paving the way for future improvements in growth of topological insulators.

Lee, J. J.; Vishik, I. M.; Ma, Y.; Shen, Z. X. [Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Schmitt, F. T.; Moore, R. G. [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, California 94305 (United States)

2012-07-02T23:59:59.000Z

44

Molecular beam epitaxy growth of high quality p-doped SnS van der Waals epitaxy on a graphene buffer layer  

Science Conference Proceedings (OSTI)

We report on the systematic investigation of optoelectronic properties of tin (IV) sulfide (SnS) van der Waals epitaxies (vdWEs) grown by molecular beam epitaxy (MBE) technique. Energy band simulation using commercial CASTEP code indicates that SnS has an indirect bandgap of size 0.982 eV. Furthermore, our simulation shows that elemental Cu can be used as a p-type dopant for the material. Growth of high quality SnS thin films is accomplished by MBE technique using graphene as the buffer layer. We observed significant reduction in the rocking curve FWHM over the existing published values. Crystallite size in the range of 2-3 {mu}m is observed which is also significantly better than the existing results. Measurement of the absorption coefficient, {alpha}, is performed using a Hitachi U-4100 Spectrophotometer system which demonstrate large values of {alpha} of the order of 10{sup 4} cm{sup -1}. Sharp cutoff in the values of {alpha}, as a function of energy, is observed for the films grown using a graphene buffer layer indicating low concentration of localized states in the bandgap. Cu-doping is achieved by co-evaporation technique. It is demonstrated that the hole concentration of the films can be controlled between 10{sup 16} cm{sup -3} and 5 x 10{sup 17}cm{sup -3} by varying the temperature of the Cu K-cell. Hole mobility as high as 81 cm{sup 2}V{sup -1}s{sup -1} is observed for SnS films on graphene/GaAs(100) substrates. The improvements in the physical properties of the films are attributed to the unique layered structure and chemically saturated bonds at the surface for both SnS and the graphene buffer layer. Consequently, the interaction between the SnS thin films and the graphene buffer layer is dominated by van der Waals force and structural defects at the interface, such as dangling bonds or dislocations, are substantially reduced.

Wang, W.; Leung, K. K.; Fong, W. K.; Wang, S. F.; Surya, C. [Department of Electronic and Information Engineering and Photonics Research Centre, Hong Kong Polytechnic University (Hong Kong); Hui, Y. Y.; Lau, S. P. [Department of Applied Physics, Hong Kong Polytechnic University (Hong Kong); Chen, Z.; Shi, L. J.; Cao, C. B. [Research Center of Materials Science, Beijing Institute of Technology, Beijing 100081 (China)

2012-05-01T23:59:59.000Z

45

Growth study of nonpolar Zn{sub 1-x}Mg{sub x}O epitaxial films on a-plane bulk ZnO by plasma-assisted molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Nonpolar Zn{sub 1-x}Mg{sub x}O epitaxial films were grown by plasma-assisted molecular beam epitaxy on a-plane ZnO substrates. A smooth surface morphology was accomplished under oxygen-rich growth conditions. The benefits of the use of ZnO substrates on the structural properties are reflected by a low-density of threading dislocations. Furthermore, no indications for the generation of basal plane stacking faults are found. The pseudomorphic growth on a-plane ZnO substrates efficiently locks the epitaxial Zn{sub 1-x}Mg{sub x}O films to the wurtzite structure up to x = 0.25. The Mg concentration is not constant and increases with larger thickness. The optical properties reflect the influence of alloy disorder.

Laumer, Bernhard [Walter Schottky Institut and Physics Department, Technische Universitaet Muenchen, Am Coulombwall 4, 85748 Garching (Germany); I. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany); Schuster, Fabian; Stutzmann, Martin [Walter Schottky Institut and Physics Department, Technische Universitaet Muenchen, Am Coulombwall 4, 85748 Garching (Germany); Bergmaier, Andreas; Dollinger, Guenther [Universitaet der Bundeswehr Muenchen, Fakultaet fuer Luft- und Raumfahrttechnik, Werner-Heisenberg-Weg 39, 85577 Neubiberg (Germany); Vogel, Stephen; Gries, Katharina I.; Volz, Kerstin [Philipps-Universitaet, Material Sciences Center-Structure and Technology Research Laboratory and Faculty of Physics, Hans-Meerwein-Strasse, 35032 Marburg (Germany); Eickhoff, Martin [I. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany)

2012-09-17T23:59:59.000Z

46

Magnetic properties of MnSb inclusions formed in GaSb matrix directly during molecular beam epitaxial growth  

Science Conference Proceedings (OSTI)

Despite of intensive search for the proper semiconductor base materials for spintronic devices working at room temperature no appropriate material based on ferromagnetic semiconductors has been found so far. We demonstrate that the phase segregated system with MnSb hexagonal inclusions inside the GaSb matrix, formed directly during the molecular beam epitaxial growth reveals the ferromagnetic properties at room temperature and is a good candidate for exploitation in spintronics. Furthermore, the MnSb inclusions with only one crystalline structure were identified in this GaMn:MnSb granular material. The SQUID magnetometry confirmed that this material exhibits ferromagnetic like behavior starting from helium up to room temperature. Moreover, the magnetic anisotropy was found which was present also at room temperature, and it was proved that by choosing a proper substrate it is possible to control the direction of easy axis of inclusions' magnetization moment between in-plane and out-of-plane; the latter is important in view of potential applications in spintronic devices.

Lawniczak-Jablonska, Krystyna; Wolska, Anna; Klepka, Marcin T.; Kret, Slawomir; Kurowska, Boguslawa; Kowalski, Bogdan J. [Institute of Physics PAS, al. Lotnikow 32/46, 02-668 Warsaw (Poland); Gosk, Jacek [Institute of Experimental Physics, University of Warsaw, Hoza 69, 00-681 Warsaw (Poland); Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw (Poland); Twardowski, Andrzej; Wasik, Dariusz; Kwiatkowski, Adam [Institute of Experimental Physics, University of Warsaw, Hoza 69, 00-681 Warsaw (Poland); Sadowski, Janusz [Institute of Physics PAS, al. Lotnikow 32/46, 02-668 Warsaw (Poland); MAX-Lab, Lund University, SE-221 00 Lund (Sweden)

2011-04-01T23:59:59.000Z

47

Effects of growth temperature on Mg-doped GaN grown by ammonia molecular beam epitaxy  

SciTech Connect

The hole concentration p in Mg-doped GaN films grown by ammonia molecular beam epitaxy depends strongly on the growth temperature T{sub GR}. At T{sub GR}=760 Degree-Sign C, GaN:Mg films showed a hole concentration of p=1.2 Multiplication-Sign 10{sup 18} cm{sup -3} for [Mg]=4.5 Multiplication-Sign 10{sup 19} cm{sup -3}, while at T{sub GR}=840 Degree-Sign C, p=4.4 Multiplication-Sign 10{sup 16} cm{sup -3} for [Mg]=7 Multiplication-Sign 10{sup 19} cm{sup -3}. Post-growth annealing did not increase p. The sample grown at 760 Degree-Sign C exhibited a low resistivity of 0.7 {Omega}cm. The mobility for all the samples was around 3-7 cm{sup 2}/V s. Temperature-dependent Hall measurements and secondary ion mass spectroscopy suggest that the samples grown at T{sub GR}>760 Degree-Sign C are compensated by an intrinsic donor rather than hydrogen.

Hurni, Christophe A.; Lang, Jordan R.; Burke, Peter G.; Speck, James S. [Materials Department, University of California, Santa Barbara, 93106-5050 California (United States)

2012-09-03T23:59:59.000Z

48

Piezoelectric InAs (211)B quantum dots grown by molecular beam epitaxy: Structural and optical properties  

Science Conference Proceedings (OSTI)

The structural and optical properties of piezoelectric (211)B InAs nanostructures grown by molecular beam epitaxy are systematically investigated as a function of the various growth parameters. Depending on the specific growth conditions, we show that the InAs nanostructures take the form of a quantum dot (QD) or a quantum dash, their height ranges between 2 and 20 nm, and their density varies from a few times 10{sup 8} cm{sup -2} all the way up to a few times 10{sup 10} cm{sup -2}. The (211)B QDs are characterized by large aspect ratios, which are compatible with a truncated pyramid morphology. By analyzing the QD emission spectrum, we conclude that only small size QDs, with heights less than 3 nm, are optically active. This is consistent with high resolution transmission electron microscopy observations showing that large QDs contain misfit dislocations, whereas small QDs are dislocation-free. The formation of a two-dimensional wetting layer is observed optically, and its thickness is determined to be between 0.30 and 0.39 nm. Finally, the large blueshift in the QD emission observed with increasing excitation power represents a clear evidence of the strong built-in piezoelectric field present in these dots.

Dialynas, G. E. [Department of Physics, University of Crete, P.O. Box 2208, 71003 Heraklion (Greece); Kalliakos, S.; Xenogianni, C. [Department of Materials Science and Technology, University of Crete, P.O. Box 2208, 71003 Heraklion (Greece); Androulidaki, M. [Microelectronics Research Group, IESL-FORTH, P.O. Box 1385, 71110 Heraklion (Greece); Kehagias, T.; Komninou, P. [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Savvidis, P. G.; Pelekanos, N. T. [Department of Materials Science and Technology, University of Crete, P.O. Box 2208, 71003 Heraklion (Greece); Microelectronics Research Group, IESL-FORTH, P.O. Box 1385, 71110 Heraklion (Greece); Hatzopoulos, Z. [Department of Physics, University of Crete, P.O. Box 2208, 71003 Heraklion (Greece); Microelectronics Research Group, IESL-FORTH, P.O. Box 1385, 71110 Heraklion (Greece)

2010-11-15T23:59:59.000Z

49

Deep levels in a-plane, high Mg-content Mg{sub x}Zn{sub 1-x}O epitaxial layers grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Deep level defects in n-type unintentionally doped a-plane Mg{sub x}Zn{sub 1-x}O, grown by molecular beam epitaxy on r-plane sapphire were fully characterized using deep level optical spectroscopy (DLOS) and related methods. Four compositions of Mg{sub x}Zn{sub 1-x}O were examined with x = 0.31, 0.44, 0.52, and 0.56 together with a control ZnO sample. DLOS measurements revealed the presence of five deep levels in each Mg-containing sample, having energy levels of E{sub c} - 1.4 eV, 2.1 eV, 2.6 V, and E{sub v} + 0.3 eV and 0.6 eV. For all Mg compositions, the activation energies of the first three states were constant with respect to the conduction band edge, whereas the latter two revealed constant activation energies with respect to the valence band edge. In contrast to the ternary materials, only three levels, at E{sub c} - 2.1 eV, E{sub v} + 0.3 eV, and 0.6 eV, were observed for the ZnO control sample in this systematically grown series of samples. Substantially higher concentrations of the deep levels at E{sub v} + 0.3 eV and E{sub c} - 2.1 eV were observed in ZnO compared to the Mg alloyed samples. Moreover, there is a general invariance of trap concentration of the E{sub v} + 0.3 eV and 0.6 eV levels on Mg content, while at least and order of magnitude dependency of the E{sub c} - 1.4 eV and E{sub c} - 2.6 eV levels in Mg alloyed samples.

Guer, Emre [Department of Physics, Faculty of Science, Atatuerk University, Erzurum 25240 (Turkey); 205 Dreese Laboratory, Department of Electrical and Computer Engineering, The Ohio State University, 2015 Neil Avenue, Columbus, Ohio 43210-1272 (United States); Tabares, G.; Hierro, A. [Dpto. Ingenieria Electronica and ISOM, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Arehart, A.; Ringel, S. A. [205 Dreese Laboratory, Department of Electrical and Computer Engineering, Ohio State University, 2015 Neil Avenue, Columbus, Ohio 43210-1272 (United States); Chauveau, J. M. [CRHEA-CNRS, 06560 Valbonne (France); University of Nice Sophia Antipolis, ParcValrose, 06102 Nice Cedex 2 (France)

2012-12-15T23:59:59.000Z

50

Deep traps in nonpolar m-plane GaN grown by ammonia-based molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Deep level defects in nonpolar m-plane GaN grown by ammonia-based molecular beam epitaxy were characterized using deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS) and compared with polar c-plane GaN that was grown simultaneously in the same growth run. Significant differences in both the levels present and their concentrations were observed upon comparison of both growth orientations. DLTS revealed electron traps with activation energies of 0.14 eV, 0.20 eV, and 0.66 eV in the m-plane material, with concentrations that were {approx}10-50 x higher than traps of similar activation energies in the c-plane material. Likewise, DLOS measurements showed {approx}20 x higher concentrations of both a C{sub N} acceptor-like state at E{sub C} - 3.26 eV, which correlates with a high background carbon concentration observed by secondary ion mass spectroscopy for the m-plane material [A. Armstrong, A. R. Arehart, B. Moran, S. P. DenBaars, U. K. Mishra, J. S. Speck, and S. A. Ringel, Appl. Phys. Lett. 84, 374 (2004)], and the V{sub Ga}-related state level at E{sub C} - 2.49 eV, which is consistent with an enhanced yellow luminescence observed by photoluminescence. The findings suggest a strong impact of growth dynamics on the incorporation of impurities and electrically active native point defects as a function of GaN growth plane polarity.

Zhang, Z.; Arehart, A. R. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Hurni, C. A.; Speck, J. S. [Department of Materials, University of California, Santa Barbara, California 93106-5050 (United States); Yang, J. [Department of Materials Science and Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Myers, R. C.; Ringel, S. A. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Department of Materials Science and Engineering, Ohio State University, Columbus, Ohio 43210 (United States)

2012-01-30T23:59:59.000Z

51

High-T{sub c} and high-J{sub c} SmFeAs(O,F) films on fluoride substrates grown by molecular beam epitaxy  

SciTech Connect

Superconducting thin films of SmFeAs(O,F) were prepared by molecular beam epitaxy on fluoride substrates. In our process, F-free SmFeAsO films were grown first, and F was subsequently introduced to the films by diffusion from an overlayer of SmF{sub 3}. By this simple process, record high T{sub c}, namely, T{sub c}{sup on} (T{sub c}{sup end}) = 57.8 K (56.4 K) was obtained in a film on CaF{sub 2}. Furthermore, the films on CaF{sub 2} showed high critical current density over 1 MA/cm{sup 2} in the self-field at 5 K. The correlation between superconductivity and epitaxial strain in SmFeAs(O,F) films is discussed.

Ueda, Shinya; Takeda, Soichiro; Takano, Shiro; Naito, Michio [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); TRIP, Japan Science and Technology Agency (JST), Chiyoda, Tokyo 102-0075 (Japan); Yamamoto, Akiyasu [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2011-12-05T23:59:59.000Z

52

Molecular beam epitaxy growth of exchange-biased PtMn/NiFe bilayers with a spontaneously ordered PtMn layer  

Science Conference Proceedings (OSTI)

We report the direct epitaxial growth of equiatomic ordered antiferromagnetic PtMn layers by molecular beam epitaxy. Such layers are used in giant magnetoresistance spin valve sensors as the antiferromagnetic pinning layer. Structural characterization and phase identification confirmed the spontaneous formation of the chemically ordered face-centered-tetragonal (L1{sub 0}) phase of PtMn with about 87.4% ordering. Based on the antiferromagnetic PtMn layer, we prepared exchange-biased PtMn/NiFe bilayers with various PtMn thicknesses. The exchange anisotropy field of the bilayer with NiFe grown on PtMn stabilizes at about 50 Oe beyond a PtMn thickness of 15 nm. Although the exchange anisotropy field is small compared to that of the polycrystalline system, the antiferromagnetic domain structure is stable over repetitive external magnetic field cycling and no training effect is observed.

Choi, Y. S.; Petford-Long, A. K.; Ward, R. C. C.; Fan, R.; Goff, J. P.; Hase, T. P. A. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Department of Physics, University of Durham, Durham DH1 3LE (United Kingdom)

2006-04-15T23:59:59.000Z

53

High electron mobility through the edge states in random networks of c-axis oriented wedge-shaped GaN nanowalls grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Transport and optical properties of random networks of c-axis oriented wedge-shaped GaN nanowalls grown spontaneously on c-plane sapphire substrates through molecular beam epitaxy are investigated. Our study suggests a one dimensional confinement of carriers at the top edges of these connected nanowalls, which results in a blue shift of the band edge luminescence, a reduction of the exciton-phonon coupling, and an enhancement of the exciton binding energy. Not only that, the yellow luminescence in these samples is found to be completely suppressed even at room temperature. All these changes are highly desirable for the enhancement of the luminescence efficiency of the material. More interestingly, the electron mobility through the network is found to be significantly higher than that is typically observed for GaN epitaxial films. This dramatic improvement is attributed to the transport of electrons through the edge states formed at the top edges of the nanowalls.

Bhasker, H. P.; Dhar, S.; Sain, A. [Physics Department, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Kesaria, Manoj; Shivaprasad, S. M. [International Centre for Material Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

2012-09-24T23:59:59.000Z

54

X-ray magnetic circular dichroism of ferromagnetic Co{sub 4}N epitaxial films on SrTiO{sub 3}(001) substrates grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

5-nm thick Co{sub 4}N layers capped with 3-nm thick Au layers were grown epitaxially on SrTiO{sub 3}(001) substrates by molecular beam epitaxy using solid Co and a radio-frequency NH{sub 3} plasma. Spin and orbital magnetic moments of the Co{sub 4}N layers were estimated using x-ray magnetic circular dichroism (XMCD) measurements at 300 K. The site-averaged Co 3d spin magnetic moment is evaluated to be about 1.4 {mu}{sub B}, which is smaller than that predicted theoretically (1.58 {mu}{sub B}). The element-specific XMCD intensities for the Co L{sub 3} edge and N K edge show that the magnetic moment is induced at the N atoms.

Ito, Keita; Harada, Kazunori; Toko, Kaoru; Suemasu, Takashi [Institute of Applied Physics, University of Tsukuba, Ibaraki 305-8573 (Japan); Ye, Mao; Kimura, Akio [Graduate School of Science, Hiroshima University, Hiroshima 739-8526 (Japan); Takeda, Yukiharu; Saitoh, Yuji [Japan Atomic Energy Agency (JAEA), SPring-8, Hyogo 679-5198 (Japan); Akinaga, Hiro [National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki 305-8569 (Japan)

2011-12-19T23:59:59.000Z

55

Strong room-temperature ferromagnetism of high-quality lightly Mn-doped ZnO grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Strong room-temperature ferromagnetism is demonstrated in single crystalline Mn-doped ZnO grown by molecular beam epitaxy. With a low Mn concentration of 2 Multiplication-Sign 10{sup 19} cm{sup -3}, Mn-doped ZnO films exhibited room-temperature ferromagnetism with a coercivity field larger than 200 Oe, a large saturation moment of 6 {mu}{sub B}/ion, and a large residue moment that is {approx}70% of the saturation magnetization. Isolated ions with long range carrier mediated spin-spin coupling may be responsible for the intrinsic ferromagnetism.

Zuo Zheng; Zhou Huimei; Olmedo, Mario J.; Kong Jieying; Liu Jianlin [Quantum Structures Laboratory, Department of Electrical Engineering, University of California - Riverside, Riverside, California 92521 (United States); Beyermann, Ward P. [Department of Physics and Astronomy, University of California - Riverside, Riverside, California 92521 (United States); Zheng Jianguo [Laboratory for Electron and X-ray Instrumentation, California Institute for Telecommunications and Information Technology, University of California - Irvine, Irvine, California 92697 (United States); Xin Yan [NHMFL, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, Florida 32310-3706 (United States)

2012-09-01T23:59:59.000Z

56

Band gap tunability of molecular beam epitaxy grown lateral composition modulated GaInP structures by controlling V/III flux ratio  

Science Conference Proceedings (OSTI)

Lateral composition modulated (LCM) GaInP structures were grown on (001) GaAs substrate by molecular beam epitaxy with different V/III flux ratios. Band gap of LCM structures could be tuned from 1.93 eV to 1.83 eV by decreasing flux ratio while maintaining the same photoluminescence intensity, enhanced light absorption, and widened absorption spectrum. It is shown that for band gap tuning of LCM structures, flux ratio adjustment is a more viable method compared to growth temperature adjustment.

Park, K. W. [School of Information and Communications, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Park, C. Y. [Micro Systems Laboratory, Samsung Advanced Institute of Technology, Yongin 446-712 (Korea, Republic of); Lee, Y. T. [School of Information and Communications, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Department of Photonics and Applied Physics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

2012-07-30T23:59:59.000Z

57

Electron scattering mechanisms in GZO films grown on a-sapphire substrates by plasma-enhanced molecular beam epitaxy  

Science Conference Proceedings (OSTI)

We report on the mechanisms governing electron transport using a comprehensive set of ZnO layers heavily doped with Ga (GZO) grown by plasma-enhanced molecular-beam epitaxy on a-plane sapphire substrates with varying oxygen-to-metal ratios and Ga fluxes. The analyses were conducted by temperature dependent Hall measurements which were supported by microstructural investigations as well. Highly degenerate GZO layers with n > 5 x 10{sup 20} cm{sup -3} grown under metal-rich conditions (reactive oxygen-to-metal ratio mobility in the temperature range from 15 to 330 K and the grain-boundary scattering governed by quantum-mechanical tunnelling is negligible. However, due to the polar nature of ZnO having high crystalline quality, polar optical phonon scattering cannot be neglected for temperatures above 150 K, because it further reduces mobility although its effect is still substantially weaker than the ionized impurity scattering even at room temperature (RT). Analysis of transport measurements and sample microstructures by x-ray diffraction and transmission electron microscopy led to a correlation between the grain sizes in these layers and mobility even for samples with a carrier concentration in the upper 10{sup 20} cm{sup -3} range. In contrast, electron transport in GZO layers grown under oxygen-rich conditions (reactive oxygen-to-metal ratio >1), which have inclined grain boundaries and relatively smaller grain sizes of 10-20 nm by x-ray diffraction, is mainly limited by compensation caused by acceptor-type point-defect complexes, presumably (Ga{sub Zn}-V{sub Zn}), and scattering on grain boundaries. The GZO layers with n mobility but with much higher RT mobility values compared to the samples grown under oxygen-rich conditions [34 vs. 7.5 cm{sup 2}/V{center_dot}s]. Properties of GZO layers grown under different conditions clearly indicate that to achieve highly conductive GZO, metal-rich conditions instead of oxygen-rich conditions have to be used.

Liu, H. Y.; Avrutin, V.; Izyumskaya, N.; Oezguer, Ue.; Morkoc, H. [Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Yankovich, A. B.; Kvit, A. V.; Voyles, P. M. [Department of Materials Science and Engineering, University Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2012-05-15T23:59:59.000Z

58

Growth and photoluminescence of self-catalyzed GaP/GaNP core/shell nanowires on Si(111) by gas source molecular beam epitaxy  

Science Conference Proceedings (OSTI)

We report a study on self-catalyzed GaP/GaNP core/shell nanowires (NWs) grown on Si(111) by gas-source molecular beam epitaxy. Scanning electron microscopy images show that vertical and uniform GaP NWs and GaP/GaNP core/shell NWs are grown on Si(111). The density ranges from {approx}1 x 10{sup 7} to {approx}5 x 10{sup 8} cm{sup -2} across the substrate. Typical diameters are {approx}110 nm for GaP NWs and {approx}220 nm for GaP/GaNP NWs. Room temperature photoluminescence (PL) signal from the GaP/GaNP core/shell NWs confirms that N is incorporated in the shell and the average N content is {approx}0.9%. The PL low-energy tail is significantly reduced, compared to bulk GaNP.

Kuang, Y. J. [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Sukrittanon, S. [Graduate Program of Material Science and Engineering, University of California, San Diego, La Jolla, California 92093 (United States); Li, H. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States); Tu, C. W. [Graduate Program of Material Science and Engineering, University of California, San Diego, La Jolla, California 92093 (United States); Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

2012-01-30T23:59:59.000Z

59

High external quantum efficiency and fill-factor InGaN/GaN heterojunction solar cells grown by NH{sub 3}-based molecular beam epitaxy  

SciTech Connect

High external quantum efficiency (EQE) p-i-n heterojunction solar cells grown by NH{sub 3}-based molecular beam epitaxy are presented. EQE values including optical losses are greater than 50% with fill-factors over 72% when illuminated with a 1 sun AM0 spectrum. Optical absorption measurements in conjunction with EQE measurements indicate an internal quantum efficiency greater than 90% for the InGaN absorbing layer. By adjusting the thickness of the top p-type GaN window contact layer, it is shown that the short-wavelength (<365 nm) quantum efficiency is limited by the minority carrier diffusion length in highly Mg-doped p-GaN.

Lang, J. R.; Hurni, C. A.; Cruz, S. C.; Matioli, E.; Speck, J. S. [Department of Materials, University of California, Santa Barbara, California 93106 (United States); Neufeld, C. J.; Mishra, U. K. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

2011-03-28T23:59:59.000Z

60

Step-flow anisotropy of the m-plane GaN (1100) grown under nitrogen-rich conditions by plasma-assisted molecular beam epitaxy  

Science Conference Proceedings (OSTI)

The homoepitaxial growth of m-plane (1100) GaN was investigated by plasma-assisted molecular beam epitaxy under nitrogen-rich conditions. The surface morphologies as a function of sample miscut were studied, providing evidence for a strong growth anisotropy that is a consequence of the anisotropy of Ga adatom diffusion barriers on the m-plane surface recently calculated ab initio[Lymperakis and Neugebauer, Phys. Rev. B 79, 241308(R) (2009)]. We found that substrate miscut toward [0001] implies a step flow toward while substrate miscut toward [0001] causes formation of atomic steps either perpendicular or parallel to the [0001] direction, under N-rich conditions at 730 deg C. We describe the growth conditions for achieving atomically flat m-plane GaN layers with parallel atomic steps.

Sawicka, Marta; Siekacz, Marcin; Skierbiszewski, Czeslaw [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, PL-01-142 Warszawa (Poland); TopGaN Ltd., Sokolowska 29/37, PL-01-142 Warszawa (Poland); Turski, Henryk; Krysko, Marcin; DziePcielewski, Igor; Grzegory, Izabella [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, PL-01-142 Warszawa (Poland); Smalc-Koziorowska, Julita [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, PL-01-142 Warszawa (Poland); TopGaN Ltd., Sokolowska 29/37, PL-01-142 Warszawa (Poland); Warsaw University of Technology, Faculty of Material Science and Engineering, Woloska 141, PL-02-507 Warszawa (Poland)

2011-06-15T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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to obtain the most current and comprehensive results.


61

Metalorganic molecular beam epitaxial growth of semi-insulating GaInAsP (? g =1.05?? m ): Fe optical waveguides for integrated photonic devices  

Science Conference Proceedings (OSTI)

Irondoping of InP and GaInAsP (? g =1.05?? m ) layers grown by metalorganic molecular beam epitaxy was studied using elemental sourcematerial in combination with a conventional effusion cell. This study was aimed at the creation of semi-insulating optical waveguides under growth conditions compatible with selective area growth. Secondary ion mass spectroscopy measurements revealed a reproducible and homogeneous incorporation behavior of the irondopant in the materials investigated. Resistivities in excess of 10 9 ??? cm were obtained for both compositions at medium doping levels. GaInAsP/InP waveguide structures grown at 485? C the minimum temperature necessary for selective depositionexhibited averaged resistivities of 510 7 ??? cm in combination with optical losses of 2.50.5? dB/cm .

H. Knzel; P. Albrecht; S. Ebert; R. Gibis; P. Harde; R. Kaiser; H. Kizuki; S. Malchow

1998-01-01T23:59:59.000Z

62

Role of adsorption kinetics in the low-temperature Si growth by gas-source molecular beam epitaxy: In situ observations and detailed modeling of the growth  

SciTech Connect

The growth rate and surface hydrogen coverage during Si gas-source molecular beam epitaxy using disilane have been obtained as functions of both the growth temperature and the source-gas pressure. The activation energy of the low-temperature (<600{sup o}C) growth rate was found to increase with the source-gas pressure, indicating a contribution by the adsorption process in these low-temperature growth kinetics. Several growth models have been constructed based on the results, among which the two-site/four-site-adsorption model [M. Suemitsu Jpn. J. Appl. Phys., Part 236, L625 (1997)] showed the best fit to both the growth rate and the hydrogen coverage. {copyright} 2001 American Institute of Physics.

Murata, Takeshi; Nakazawa, Hideki; Tsukidate, Yoshikazu; Suemitsu, Maki

2001-08-06T23:59:59.000Z

63

Properties of molecular beam epitaxy grown Eu{sub x}(transition metal){sub y} films (transition metals: Mn, Cr)  

Science Conference Proceedings (OSTI)

The electronic and crystallographic structures, as well as the magnetic properties, of Eu{sub x}(transition metal){sub y} (transition metals: Mn, Cr) thin films grown by molecular beam epitaxy were studied. Relative changes of the Eu/Mn and Eu/Cr ratios derived from the XPS lines, as well as x-ray reflectivity, indicate mixing of the Eu/Mn and Eu/Cr layers. Valency transitions from Eu{sup 2+} to Eu{sup 3+} were observed in both systems for most studied stoichiometries. A transition to a magnetically ordered phase was observed at 15 K, 40 K, and 62 K for selected films in the Eu-Mn system, and at 50 K for the film with a Eu/Cr ratio of 0.5.

Balin, K. [A. Chelkowski Institute of Physics, University of Silesia, Katowice, 40-007 (Poland); Center for Magnetism and Magnetic Nanostructures, University of Colorado at Colorado Springs, Colorado Springs, Colorado 80918 (United States); Nowak, A. [A. Chelkowski Institute of Physics, University of Silesia, Katowice, 40-007 (Poland); Laboratoire de Physique de l'Etat Condense, University du Maine, Le Mans Cedex, 72085 (France); Gibaud, A. [Laboratoire de Physique de l'Etat Condense, University du Maine, Le Mans Cedex, 72085 (France); Szade, J. [A. Chelkowski Institute of Physics, University of Silesia, Katowice, 40-007 (Poland); Celinski, Z. [Center for Magnetism and Magnetic Nanostructures, University of Colorado at Colorado Springs, Colorado Springs, Colorado 80918 (United States)

2011-04-01T23:59:59.000Z

64

Clarification of enhanced ferromagnetism in Be-codoped InMnP fabricated using Mn/InP:Be bilayers grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

The p-type InMnP:Be epilayers were prepared by the sequential growth of Mn/InP:Be bilayers using molecular-beam-epitaxy and the subsequent in-situ annealing at 200-300 deg. C. In triple-axis x-ray diffraction patterns, the samples revealed a shoulder peak indicative of intrinsic InMnP. The ferromagnetic transition in InMnP:Be was observed to occur at the elevated temperature of {approx}140 K, and the ferromagnetic spin-domains clearly appeared in magnetic force microscopy images. The improved ferromagnetic properties are attributed to the increased p-d hybridation due to high p-type conductivity of InMnP:Be (p {approx} 10{sup 20 }cm{sup -3}). The results suggest that enhanced ferromagnetism can be effectively obtained from Be-codoped InMnP.

Shon, Yoon; Lee, Sejoon; Taek Yoon, Im; Jeon, H. C.; Lee, D. J.; Kang, T. W. [Quantum-functional Semiconductor Research Center, Dongguk University-Seoul, Seoul 100-715 (Korea, Republic of); Song, J. D. [Center for Spintronics Research, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Yoon, Chong S. [Department of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, D. Y. [Department of Semiconductor Science, Dongguk University-Seoul, Seoul 100-715 (Korea, Republic of); Park, C. S. [School of Electrical Engineering, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-713 (Korea, Republic of)

2011-11-07T23:59:59.000Z

65

Formation behavior of Be{sub x}Zn{sub 1-x}O alloys grown by plasma-assisted molecular beam epitaxy  

SciTech Connect

We report the phase formation behavior of Be{sub x}Zn{sub 1-x}O alloys grown by plasma-assisted molecular beam epitaxy. We find the alloy with low- and high-Be contents could be obtained by alloying BeO into ZnO films. X-ray diffraction measurements shows the c lattice constant value shrinks, and room temperature absorption shows the energy band-gap widens after Be incorporated. However, the alloy with intermediate Be composition are unstable and segregated into low- and high-Be contents BeZnO alloys. We demonstrate the phase segregation of Be{sub x}Zn{sub 1-x}O alloys with intermediate Be composition resulted from large internal strain induced by large lattice mismatch between BeO and ZnO.

Chen, Mingming; Zhu, Yuan; Su, Longxing; Zhang, Quanlin; Chen, Anqi; Ji, Xu; Xiang, Rong; Gui, Xuchun; Wu, Tianzhun [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)] [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Pan, Bicai [Department of Physics and Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Department of Physics and Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Tang, Zikang [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China) [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

2013-05-20T23:59:59.000Z

66

Molecular beam epitaxy of InAlN lattice-matched to GaN with homogeneous composition using ammonia as nitrogen source  

Science Conference Proceedings (OSTI)

InAlN lattice-matched to GaN was grown by molecular beam epitaxy (MBE) using ammonia as the nitrogen source. The alloy composition, growth conditions, and strain coherence of the InAlN were verified by high resolution x-ray diffraction {omega}-2{theta} scans and reciprocal space maps. Scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy of the InAlN revealed the absence of lateral composition modulation that was observed in the films grown by plasma-assisted MBE. InAlN/AlN/GaN high electron mobility transistors with smooth surfaces were fabricated with electron mobilities exceeding 1600 cm{sup 2}/Vs and sheet resistances below 244 {Omega}/sq.

Wong, Man Hoi; Wu Feng; Hurni, Christophe A.; Choi, Soojeong; Speck, James S.; Mishra, Umesh K. [Department of Electrical and Computer Engineering and Materials Department, University of California, Santa Barbara, California 93106 (United States)

2012-02-13T23:59:59.000Z

67

Effect of AlN buffer layer properties on the morphology and polarity of GaN nanowires grown by molecular beam epitaxy  

SciTech Connect

Low-temperature AlN buffer layers grown via plasma-assisted molecular beam epitaxy on Si (111) were found to significantly affect the subsequent growth morphology of GaN nanowires. The AlN buffer layers exhibited nanowire-like columnar protrusions, with their size, shape, and tilt determined by the AlN V/III flux ratio. GaN nanowires were frequently observed to adopt the structural characteristics of the underlying AlN columns, including the size and the degree of tilt. Piezoresponse force microscopy and polarity-sensitive etching indicate that the AlN films and the protruding columns have a mixed crystallographic polarity. Convergent beam electron diffraction indicates that GaN nanowires are Ga-polar, suggesting that Al-polar columns are nanowire nucleation sites for Ga-polar nanowires. GaN nanowires of low density could be grown on AlN buffers that were predominantly N-polar with isolated Al-polar columns, indicating a high growth rate for Ga-polar nanowires and suppressed growth of N-polar nanowires under typical growth conditions. AlN buffer layers grown under slightly N-rich conditions (V/III flux ratio = 1.0 to 1.3) were found to provide a favorable growth surface for low-density, coalescence-free nanowires.

Brubaker, Matt D. [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); DARPA Center for Integrated Micro/Nano-Electromechanical Transducers (iMINT), University of Colorado, Boulder, Colorado 80309 (United States); Levin, Igor; Davydov, Albert V. [Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Rourke, Devin M.; Sanford, Norman A.; Bertness, Kris A. [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Bright, Victor M. [Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); DARPA Center for Integrated Micro/Nano-Electromechanical Transducers (iMINT), University of Colorado, Boulder, Colorado 80309 (United States)

2011-09-01T23:59:59.000Z

68

Indium and impurity incorporation in InGaN films on polar, nonpolar, and semipolar GaN orientations grown by ammonia molecular beam epitaxy  

SciTech Connect

The effects of NH{sub 3} flow, group III flux, and substrate growth temperature on indium incorporation and surface morphology have been investigated for bulk InGaN films grown by ammonia molecular beam epitaxy. The incorporation of unintentional impurity elements (H, C, O) in InGaN films was studied as a function of growth temperature for growth on polar (0001) GaN on sapphire templates, nonpolar (1010) bulk GaN, and semipolar (1122), (2021) bulk GaN substrates. Enhanced indium incorporation was observed on both (1010) and (2021) surfaces relative to c-plane, while reduced indium incorporation was observed on (1122) for co-loaded conditions. Indium incorporation was observed to increase with decreasing growth temperature for all planes, while being relatively unaffected by the group III flux rates for a 1:1 Ga:In ratio. Indium incorporation was found to increase at the expense of a decreased growth rate for higher ammonia flows; however, smooth surface morphology was consistently observed for growth on semipolar orientations. Increased concentrations of oxygen and hydrogen were observed on semipolar and nonpolar orientations with a clear trend of increased hydrogen incorporation with indium content.

Browne, David A.; Young, Erin C.; Lang, Jordan R.; Hurni, Christophe A.; Speck, James S. [Materials Department, University of California Santa Barbara, Santa Barbara, California 93106 (United States)

2012-07-15T23:59:59.000Z

69

Optical, magnetic, and transport behaviors of Ge{sub 1-x}Mn{sub x}Te ferromagnetic semiconductors grown by molecular-beam epitaxy  

SciTech Connect

The optical, magnetic, and transport behaviors of Ge{sub 1-x}Mn{sub x}Te (x=0.24 and 0.55) grown by solid-source molecular-beam epitaxy are investigated. X-ray diffraction shows that Ge{sub 1-x}Mn{sub x}Te crystallizes in rocksalt structure. The temperature-dependent magnetization (M-T) for x=0.55 sample gives a Curie paramagnetic temperature of {theta}{sub p}{approx}180 K, which is consistent with the temperature-dependent resistivity {rho}(T) measurement. Anomalous Hall effect is clearly observed in the samples and can be attributed to extrinsic skew scattering based on the scaling relationship of {rho}{sub xy}{proportional_to}{rho}{sub xx}{sup 1.06}. The magnetoresistance of Ge{sub 1-x}Mn{sub x}Te is isotropic and displays a clear hysterestic loop at low temperature, which resembles that of giant-magnetoresistance granular system in solids.

Chen, W. Q.; Bi, J. F.; Teo, K. L.; Liew, T.; Chong, T. C. [Information Storage Materials Laboratory, Electrical and Computer Engineering Department, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Singapore and Data Storage Institute, 5 Engineering Drive 1, Singapore 117608 (Singapore); Lim, S. T.; Sim, C. H. [Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456 (Singapore)

2008-09-15T23:59:59.000Z

70

Photoconduction efficiencies and dynamics in GaN nanowires grown by chemical vapor deposition and molecular beam epitaxy: A comparison study  

Science Conference Proceedings (OSTI)

The normalized gains, which determines the intrinsic photoconduction (PC) efficiencies, have been defined and compared for the gallium nitride (GaN) nanowires (NWs) grown by chemical vapor deposition (CVD) and molecular beam epitaxy (MBE). By excluding the contributions of experimental parameters and under the same light intensity, the CVD-grown GaN NWs exhibit the normalized gain which is near two orders of magnitude higher than that of the MBE-ones. The temperature-dependent time-resolved photocurrent measurement further indicates that the higher photoconduction efficiency in the CVD-GaN NWs is originated from the longer carrier lifetime induced by the higher barrier height ({phi}{sub B} = 160 {+-} 30 mV) of surface band bending. In addition, the experimentally estimated barrier height at 20 {+-} 2 mV for the MBE-GaN NWs, which is much lower than the theoretical value, is inferred to be resulted from the lower density of charged surface states on the non-polar side walls.

Chen, R. S. [Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Tsai, H. Y. [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Huang, Y. S. [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Chen, Y. T. [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China); Chen, L. C. [Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China); Chen, K. H. [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China); Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China)

2012-09-10T23:59:59.000Z

71

Strain relaxation in GaN/Al{sub x}Ga{sub 1-x}N superlattices grown by plasma-assisted molecular-beam epitaxy  

SciTech Connect

We have investigated the misfit relaxation process in GaN/Al{sub x}Ga{sub 1-x}N (x = 0.1, 0.3, 0.44) superlattices (SL) deposited by plasma-assisted molecular beam epitaxy. The SLs under consideration were designed to achieve intersubband absorption in the mid-infrared spectral range. We have considered the case of growth on GaN (tensile stress) and on AlGaN (compressive stress) buffer layers, both deposited on GaN-on-sapphire templates. Using GaN buffer layers, the SL remains almost pseudomorphic for x = 0.1, 0.3, with edge-type threading dislocation densities below 9 x 10{sup 8} cm{sup -2} to 2 x 10{sup 9} cm{sup -2}. Increasing the Al mole fraction to 0.44, we observe an enhancement of misfit relaxation resulting in dislocation densities above 10{sup 10} cm{sup -2}. In the case of growth on AlGaN, strain relaxation is systematically stronger, with the corresponding increase in the dislocation density. In addition to the average relaxation trend of the SL, in situ measurements indicate a periodic fluctuation of the in-plane lattice parameter, which is explained by the different elastic response of the GaN and AlGaN surfaces to the Ga excess at the growth front. The results are compared with GaN/AlN SLs designed for near-infrared intersubband absorption.

Kotsar, Y.; Bellet-Amalric, E.; Das, A.; Monroy, E. [CEA-Grenoble, INAC/SP2M/NPSC, 17 Rue des Martyrs, 38054 Grenoble cedex 9 (France); Doisneau, B. [SIMaP, Grenoble INP, Domaine Universitaire, BP 75, 38402 Saint Martin d'Heres (France); Sarigiannidou, E. [LMGP, Grenoble INP, 3 Parvis Louis Neel, BP 257, 38016 Grenoble cedex 1 (France)

2011-08-01T23:59:59.000Z

72

The adsorption-controlled growth of LuFe{sub 2}O{sub 4} by molecular-beam epitaxy  

Science Conference Proceedings (OSTI)

We report the growth of single-phase (0001)-oriented epitaxial films of the purported electronically driven multiferroic, LuFe{sub 2}O{sub 4}, on (111) MgAl{sub 2}O{sub 4}, (111) MgO, and (0001) 6H-SiC substrates. Film stoichiometry was regulated using an adsorption-controlled growth process by depositing LuFe{sub 2}O{sub 4} in an iron-rich environment at pressures and temperatures where excess iron desorbs from the film surface during growth. Scanning transmission electron microscopy reveals reaction-free film-substrate interfaces. The magnetization increases rapidly below 240 K, consistent with the paramagnetic-to-ferrimagnetic phase transition of bulk LuFe{sub 2}O{sub 4}. In addition to the {approx}0.35 eV indirect band gap, optical spectroscopy reveals a 3.4 eV direct band gap at the gamma point.

Brooks, Charles M. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Misra, Rajiv; Schiffer, Peter [Department of Physics and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Mundy, Julia A. [School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States); Zhang Lei, A.; Liu Zikui [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Holinsworth, Brian S.; O'Neal, Kenneth R.; Musfeldt, Janice L. [Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996 (United States); Heeg, Tassilo [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Zander, Willi; Schubert, J. [Peter Gruenberg Institut (PGI-9), JARA-Fundamentals of Future Information Technologies, Research Centre Juelich, D-52425 Juelich (Germany); Muller, David A. [School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States); Schlom, Darrell G. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

2012-09-24T23:59:59.000Z

73

Influence of V/III growth flux ratio on trap states in m-plane GaN grown by ammonia-based molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS) were utilized to investigate the behavior of deep states in m-plane, n-type GaN grown by ammonia-based molecular beam epitaxy (NH{sub 3}-MBE) as a function of systematically varied V/III growth flux ratios. Levels were detected at E{sub C} - 0.14 eV, E{sub C} - 0.21 eV, E{sub C} - 0.26 eV, E{sub C} - 0.62 eV, E{sub C} - 0.67 eV, E{sub C} - 2.65 eV, and E{sub C} - 3.31 eV, with the concentrations of several traps exhibiting systematic dependencies on V/III ratio. The DLTS spectra are dominated by traps at E{sub C} - 0.14 eV and E{sub C} - 0.67 eV, whose concentrations decreased monotonically with increasing V/III ratio and decreasing oxygen impurity concentration, and by a trap at E{sub C} - 0.21 eV that revealed no dependence of its concentration on growth conditions, suggestive of different physical origins. Higher concentrations of deeper trap states detected by DLOS with activation energies of E{sub C} - 2.65 eV and E{sub C} - 3.31 eV in each sample did not display measureable sensitivity to the intentionally varied V/III ratio, necessitating further study on reducing these deep traps through growth optimization for maximizing material quality of NH{sub 3}-MBE grown m-plane GaN.

Zhang, Z.; Arehart, A. R. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Hurni, C. A.; Speck, J. S. [Department of Materials, University of California, Santa Barbara, California 93106-5050 (United States); Ringel, S. A. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Institute for Materials Research, Ohio State University, Columbus, Ohio 43210 (United States)

2012-10-08T23:59:59.000Z

74

Structural, morphological, and magnetic characterization of In{sub 1-x}Mn{sub x}As quantum dots grown by molecular beam epitaxy  

SciTech Connect

In this paper, we present a method to order low temperature (LT) self-assembled ferromagnetic In{sub 1-x}Mn{sub x}As quantum dots (QDs) grown by molecular beam epitaxy (MBE). The ordered In{sub 1-x}Mn{sub x}As QDs were grown on top of a non-magnetic In{sub 0.4}Ga{sub 0.6}As/GaAs(100) QDs multi-layered structure. The modulation of the chemical potential, due to the stacking, provides a nucleation center for the LT In{sub 1-x}Mn{sub x}As QDs. For particular conditions, such as surface morphology and growth conditions, the In{sub 1-x}Mn{sub x}As QDs align along lines like chains. This work also reports the characterization of QDs grown on plain GaAs(100) substrates, as well as of the ordered structures, as function of Mn content and growth temperature. The substitutional Mn incorporation in the InAs lattice and the conditions for obtaining coherent and incoherent structures are discussed from comparison between Raman spectroscopy and x-ray analysis. Ferromagnetic behavior was observed for all structures at 2 K. We found that the magnetic moment axis changes from [110] in In{sub 1-x}Mn{sub x}As over GaAs to [1-10] for the ordered In{sub 1-x}Mn{sub x}As grown over GaAs template.

Ferri, F. A.; Marega, E. Jr. [Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Sao Carlos 13560-970, SP (Brazil); Coelho, L. N. [Instituto de Fisica, Universidade de Brasilia, Brasilia 70919-970, DF (Brazil); Kunets, V. P.; Salamo, G. J. [Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

2012-08-01T23:59:59.000Z

75

Strain control of AlGaN/GaN high electron mobility transistor structures on silicon (111) by plasma assisted molecular beam epitaxy  

Science Conference Proceedings (OSTI)

This paper reports on the use of plasma assisted molecular beam epitaxy of AlGaN/GaN-based high electron mobility transistor structures grown on 4 in. Si (111) substrates. In situ measurements of wafer curvature during growth proved to be a very powerful method to analyze the buffer layer's thickness dependent strain. The Ga/N ratio at the beginning of growth of the GaN buffer layer is the critical parameter to control the compressive strain of the entire grown structure. An engineered amount of compressive strain must be designed into the structure to perfectly compensate for the tensile strain caused by differences in the thermal expansion coefficient between the epi-layer and substrate during sample cool down from growth temperatures. A maximum film thickness of 4.2 {mu}m was achieved without the formation of any cracks and a negligible bow of the wafers below 10 {mu}m. Measurement of the as-grown wafers revealed depth profiles of the charge carrier concentration comparable to values achieved on SiC substrates and mobility values of the two dimensional electron gas in the range 1230 to 1350 cm{sup 2}/Vs at a charge carrier concentration of 6.5-7 10{sup 12}/cm{sup 2}. First results on processed wafers with 2 {mu}m thick buffer layer indicate very promising results with a resistance of the buffer, measured on 200 {mu}m long contacts with 15 {mu}m pitch, in the range of R > 10{sup 9}{Omega} at 100 V and breakdown voltages up to 550 V.

Aidam, Rolf; Diwo, Elke; Rollbuehler, Nicola; Kirste, Lutz; Benkhelifa, Fouad [Fraunhofer-Institute for Applied Solid State Physics, Tullastrasse 72, 79108 Freiburg (Germany)

2012-06-01T23:59:59.000Z

76

High quality ultrathin Bi{sub 2}Se{sub 3} films on CaF{sub 2} and CaF{sub 2}/Si by molecular beam epitaxy with a radio frequency cracker cell  

Science Conference Proceedings (OSTI)

We report a method to fabricate high quality Bi{sub 2}Se{sub 3} thin films using molecular beam epitaxy with a radio frequency cracker cell as an atomic selenium source. With Se-to-Bi ratios close to exact stoichiometry, optimal layer-by-layer growth of high quality Bi{sub 2}Se{sub 3} thin films with smooth surfaces has been achieved on CaF{sub 2}(111) substrates and Si(111) substrates with a thin epitaxial CaF{sub 2} buffer layer (CaF{sub 2}/Si). Transport measurements show a characteristic weak-antilocalization magnetoresistance in all the films, with the emergence of a weak-localization contribution in the ultrathin film limit. Quantum oscillations, attributed to the topological surface states have been observed, including in films grown on CaF{sub 2}/Si.

Zhang Li; Dolev, Merav [Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305 (United States); Hammond, Robert [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305 (United States); Liu Min [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); Palevski, Alexander [School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel); Kapitulnik, Aharon [Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States)

2012-10-08T23:59:59.000Z

77

Molecular Beam Epitaxial Growth of Bi2Te3 and Sb2Te3 Topological Insulators on GaAs (111) Substrates: A Potential Route to Fabricate Topological Insulator p-n Junction  

E-Print Network (OSTI)

High quality Bi2Te3 and Sb2Te3 topological insulators films were epitaxially grown on GaAs (111) substrate using solid source molecular beam epitaxy. Their growth and behavior on both vicinal and non-vicinal GaAs (111) substrates were investigated by reflection high-energy electron diffraction, atomic force microscopy, x-ray diffraction, and high resolution transmission electron microscopy. It is found that non-vicinal GaAs (111) substrate is better than a vicinal substrate to provide high quality Bi2Te3 and Sb2Te3 films. Hall and magnetoresistance measurements indicate that p type Sb2Te3 and n type Bi2Te3 topological insulator films can be directly grown on a GaAs (111) substrate, which may pave a way to fabricate topological insulator p-n junction on the same substrate, compatible with the fabrication process of present semiconductor optoelectronic devices.

Zhaoquan Zeng; Timothy A. Morgan; Dongsheng Fan; Chen Li; Yusuke Hirono; Xian Hu; Yanfei Zhao; Joon Sue Lee; Zhiming M. Wang; Jian Wang; Shuiqing Yu; Michael E. Hawkridge; Mourad Benamara; Gregory J. Salamo

2013-01-03T23:59:59.000Z

78

Optical properties of a-plane (Al, Ga)N/GaN multiple quantum wells grown on strain engineered Zn{sub 1-x}Mg{sub x}O layers by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Nonpolar (1120) Al{sub 0.2}Ga{sub 0.8}N/GaN multiple quantum wells (MQWs) have been grown by molecular beam epitaxy on (1120) Zn{sub 0.74}Mg{sub 0.26}O templates on r-plane sapphire substrates. The quantum wells exhibit well-resolved photoluminescence peaks in the ultra-violet region, and no sign of quantum confined Stark effect is observed in the complete multiple quantum well series. The results agree well with flat band quantum well calculations. Furthermore, we show that the MQW structures are strongly polarized along the [0001] direction. The origin of the polarization is discussed in terms of the strain anisotropy dependence of the exciton optical oscillator strengths.

Xia, Y.; Vinter, B.; Chauveau, J.-M. [CRHEA-CNRS, Rue Bernard Gregory, 06560 Valbonne (France); University of Nice Sophia-Antipolis, 06103 Nice (France); Brault, J.; Nemoz, M.; Teisseire, M.; Leroux, M. [CRHEA-CNRS, Rue Bernard Gregory, 06560 Valbonne (France)

2011-12-26T23:59:59.000Z

79

Two-dimensional weak anti-localization in Bi{sub 2}Te{sub 3} thin film grown on Si(111)-(7 Multiplication-Sign 7) surface by molecular beam epitaxy  

SciTech Connect

We report on low temperature transport studies of Bi{sub 2}Te{sub 3} topological insulator thin films grown on Si(111)-(7 Multiplication-Sign 7) surface by molecular beam epitaxy. A sharp increase in the magnetoresistance with magnetic field at low temperature indicates the existence of weak anti-localization. The measured weak anti-localization effect agrees well with the Hikami-Larkin-Nagaoka model, and the extracted phase coherence length shows a power-law dependence with temperature indicating the existence of a two-dimensional system. An insulating ground state has also been observed at low temperature showing a logarithmic divergence of the resistance that appears to be the influence of electron-electron interaction in a two-dimensional system.

Roy, Anupam; Guchhait, Samaresh; Sonde, Sushant; Dey, Rik; Pramanik, Tanmoy; Rai, Amritesh; Movva, Hema C. P.; Banerjee, Sanjay K. [Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States)] [Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States); Colombo, Luigi [Texas Instruments, 12500 TI Boulevard, Dallas, Texas 75266 (United States)] [Texas Instruments, 12500 TI Boulevard, Dallas, Texas 75266 (United States)

2013-04-22T23:59:59.000Z

80

H2S molecular beam passivation of Ge(001)  

Science Conference Proceedings (OSTI)

A fundamental issue regarding the introduction of high-mobility Ge channels in CMOS circuits is the electrical passivation of the interface with the high-k gate dielectric. In this paper, we investigate the passivation of p-Ge(001) using molecular H"2S. ... Keywords: H2S, High- semiconductors, Molecular beam epitaxy, Passivation

C. Merckling; Y. C. Chang; C. Y. Lu; J. Penaud; M. El-Kazzi; F. Bellenger; G. Brammertz; M. Hong; J. Kwo; M. Meuris; J. Dekoster; M. M. Heyns; M. Caymax

2011-04-01T23:59:59.000Z

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81

Application of hydrogenation to low-temperature cleaning of the Si(001) surface in the processes of molecular-beam epitaxy: Investigation by scanning tunneling microscopy, reflected high-energy electron diffraction, and high resolution transmission electron microscopy  

Science Conference Proceedings (OSTI)

Structural properties of the clean Si(001) surface obtained as a result of low-temperature (470-650 Degree-Sign C) pre-growth annealings of silicon wafers in a molecular-beam epitaxy chamber have been investigated. To decrease the cleaning temperature, a silicon surface was hydrogenated in the process of a preliminary chemical treatment in HF and NH{sub 4}F aqueous solutions. It has been shown that smooth surfaces composed of wide terraces separated by monoatomic steps can be obtained by dehydrogenation at the temperatures Greater-Than-Or-Equivalent-To 600 Degree-Sign C, whereas clean surfaces obtained at the temperatures clean surfaces on the temperature of hydrogen thermal desorption and the process of the preliminary chemical treatment. The frequency of detachment/attachment of Si dimers from/to the steps and effect of the Ehrlich-Schwoebel barrier on ad-dimer migration across steps have been found to be the most probable factors determining a degree of the resultant surface roughness.

Arapkina, L. V.; Krylova, L. A.; Chizh, K. V.; Chapnin, V. A.; Uvarov, O. V.; Yuryev, V. A. [A. M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilov Street, Moscow 119991 (Russian Federation)

2012-07-01T23:59:59.000Z

82

Molecular beam epitaxial growth of metamorphic AlInSb/GaInSb high-electron-mobility-transistor structures on GaAs substrates for low power and high frequency applications  

Science Conference Proceedings (OSTI)

We report on molecular beam epitaxial growth of AlInSb/GaInSb metamorphic high-electron-mobility-transistor structures for low power, high frequency applications on 4 in. GaAs substrates. The structures consist of a Ga{sub 0.4}In{sub 0.6}Sb channel embedded in Al{sub 0.4}In{sub 0.6}Sb barrier layers which are grown on top of an insulating metamorphic buffer, which is based on the linear exchange of Ga versus In and a subsequent exchange of As versus Sb. Precise control of group V fluxes and substrate temperature in the Al{sub 0.4}In{sub 0.6}As{sub 1-x}Sb{sub x} buffer is essential to achieve high quality device structures. Good morphological properties were achieved demonstrated by the appearance of crosshatching and root mean square roughness values of 2.0 nm. Buffer isolation is found to be >100 k{Omega}/{open_square} for optimized growth conditions. Hall measurements at room temperature reveal electron densities of 2.8x10{sup 12} cm{sup -2} in the channel at mobility values of 21.000 cm{sup 2}/V s for single-sided Te volume doping and 5.4x10{sup 12} cm{sup -2} and 17.000 cm{sup 2}/V s for double-sided Te {delta}-doping, respectively.

Loesch, R.; Aidam, R.; Kirste, L.; Leuther, A. [Fraunhofer Institute for Applied Solid-State Physics (IAF), Tullastrasse 72, 79108 Freiburg (Germany)

2011-02-01T23:59:59.000Z

83

Molecular beam kinetics  

SciTech Connect

The design of a crossed molecular beam ''supermachine'' for neutral-- neutral collisions is discussed. The universal electron bombardment ionizer, mass filter, and ion detection system of the detector, the supersonic nozzle sources, the differential pumping arrangement for the sources and detector, the time-of-flight detection of scattered products, and the overall configuration of the apparatus are described. The elastic scattering of two systems, CH$sub 4$ + Ar and NH$sub 3$ + Ar, has been measured using the supermachine with two supersonic nozzle sources. The rainbow structure and the interference oscillations are seen in each system. The best fit to the data was found using a Morse--Spline--Van der Waals (MSV) potential. The three potential parameters epsilon, r/sub m/, and $beta$ were found to be 2.20(+-0.04) x 10$sup -14$ ergs, 3.82(+-0.04)A, and 7.05 +- 0.20 for CH$sub 4$ + Ar, and 2.21(+-0.04) x 10$sup - 14$ ergs 3.93 (+-0.05)A, and 8.45 +- 0.30 for NH$sub 3$ + Ar. A new phenomenon in crossed molecular beams of condensation of a molecule on a cluster to form a complex was observed. A bromine molecule condensed on clusters of chlorine (Cl$sub 2$)/sub chi/ and ammonia (NH$sub 3$)/sub chi/. The value of chi for measurements in these experiments ranges from 7 to 40 for chlorine clusters and from 10 to 70 ammonia clusters. (auth)

Behrens, R. Jr.

1975-11-01T23:59:59.000Z

84

Growth temperature dependence of epitaxial Gd2O3 films on Si(111)  

Science Conference Proceedings (OSTI)

This article reports on the epitaxy of crystalline high @k oxide Gd"2O"3 layers on Si(111) for CMOS gate application. Epitaxial Gd"2O"3 thin films have been grown by Molecular Beam Epitaxy (MBE) on Si(111) substrates between 650 and 750^oC. The structural ... Keywords: Crystalline high ? oxide, Electrical properties, Gd2O3, Molecular beam epitaxy

G. Niu; B. Vilquin; N. Baboux; C. Plossu; L. Becerra; G. Saint-Grions; G. Hollinger

2009-07-01T23:59:59.000Z

85

14th international symposium on molecular beams  

SciTech Connect

This report discusses research being conducted with molecular beams. The general topic areas are as follows: Clusters I; reaction dynamics; atomic and molecular spectroscopy; clusters II; new techniques; photodissociation & dynamics; and surfaces.

Not Available

1992-09-01T23:59:59.000Z

86

14th international symposium on molecular beams  

Science Conference Proceedings (OSTI)

This report discusses research being conducted with molecular beams. The general topic areas are as follows: Clusters I; reaction dynamics; atomic and molecular spectroscopy; clusters II; new techniques; photodissociation dynamics; and surfaces.

Not Available

1992-01-01T23:59:59.000Z

87

Yuan T. Lee's Crossed Molecular Beam Experiment  

NLE Websites -- All DOE Office Websites (Extended Search)

Yuan T. Lee's Crossed Molecular Beam Experiment Yuan T. Lee's Crossed Molecular Beam Experiment Home | Staff | Search | Advisory Committee | User Facilities | Laboratories | Congress | Budget Yuan T. Lee's Crossed Molecular Beam Experiment http://web.archive.org/web/20000902074635/www.er.doe.gov/production/bes/YuanLee_Exp.html (1 of 4)4/7/2006 2:46:13 PM Yuan T. Lee's Crossed Molecular Beam Experiment The above illustration was drawn by Professor Yuan T. Lee, who shared the 1986 Nobel Prize in Chemistry. It shows the design for his crossed molecular beam experiment described in the story beginning on page 27 of "Basic Energy Sciences: Summary of Accomplishments" (DOE/ER-0455P, May 1990); the story is also copied below. The purpose of this experiment was to study the chemical reaction of sodium atoms with oxygen molecules. In the experiment, a beam of sodium atoms (green,

88

Impacts of anisotropic lattice relaxation on crystal mosaicity and luminescence spectra of m-plane Al{sub x}Ga{sub 1-x}N films grown on m-plane freestanding GaN substrates by NH{sub 3} source molecular beam epitaxy  

SciTech Connect

In-plane anisotropic lattice relaxation was correlated with the crystal mosaicity and luminescence spectra for m-plane Al{sub x}Ga{sub 1-x}N films grown on a freestanding GaN substrate by NH{sub 3}-source molecular beam epitaxy. The homoepitaxial GaN film exhibited A- and B-excitonic emissions at 8 K, which obeyed the polarization selection rules. For Al{sub x}Ga{sub 1-x}N overlayers, the m-plane tilt mosaic along c-axis was the same as the substrate as far as coherent growth was maintained (x{<=}0.25). However, it became more severe than along the a-axis for lattice-relaxed films (x{>=}0.52). The results are explained in terms of anisotropic lattice and thermal mismatches between the film and the substrate. Nonetheless, all the Al{sub x}Ga{sub 1-x}N films exhibited a near-band-edge emission peak and considerably weak deep emission at room temperature.

Hoshi, T.; Hazu, K.; Ohshita, K.; Kagaya, M.; Onuma, T.; Chichibu, S. F. [CANTech, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577 (Japan); Fujito, K. [Optoelectronics Laboratory, Mitsubishi Chemical Corporation, 1000 Higashi-Mamiana, Ushiku 300-1295 (Japan); Namita, H. [Mitsubishi Chemical Group Science and Technology Research Center, Inc., 8-3-1 Chuo, Ami, Inashiki 300-0332 (Japan)

2009-02-16T23:59:59.000Z

89

Low-temperature formation of epitaxial graphene on 6H-SiC induced by continuous electron beam irradiation  

Science Conference Proceedings (OSTI)

It is observed that epitaxial graphene forms on the surface of a 6H-SiC substrate by irradiating electron beam directly on the sample surface in high vacuum at relatively low temperature ({approx}670 Degree-Sign C). The symmetric shape and full width at half maximum of 2D peak in the Raman spectra indicate that the formed epitaxial graphene is turbostratic. The gradual change of the Raman spectra with electron beam irradiation time increasing suggests that randomly distributed small grains of epitaxial graphene form first and grow laterally to cover the entire irradiated area. The sheet resistance of epitaxial graphene film is measured to be {approx}6.7 k{Omega}/sq.

Go, Heungseok; Jeon, Youngeun; Park, Kibog [School of Electrical and Computer Engineering, KIER-UNIST Advanced Center for Energy, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); Kwak, Jinsung; Yoo, Jung-Woo; Youb Kim, Sung; Kwon, Soon-Yong [School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); Kim, Sung-Dae; Kim, Young-Woon [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Cheol Lee, Byung; Suk Kang, Hyun [Quantum Optics Laboratory, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Ko, Jae-Hyeon [Department of Physics, Hallym University, Chuncheon Gangwondo 200-702 (Korea, Republic of); Kim, Nam [Division of Convergence Technology, Korea Research Institute of Standards and Science, Daejeon 305-340 (Korea, Republic of); Kim, Bum-Kyu [Department of Physics, Chonbuk National University, Jeonju Chonbuk 561-756 (Korea, Republic of)

2012-08-27T23:59:59.000Z

90

Integration of functional epitaxial oxides into silicon: from high-k application to nanostructures  

Science Conference Proceedings (OSTI)

We will present results for crystalline gadolinium oxides on silicon in the cubic bixbyite structure grown by solid source molecular beam epitaxy. Additional oxygen supply during growth improves the dielectric properties significantly. Experimental results ... Keywords: Gadolinium oxide, Heterostructures, High-k material, Molecular beam epitaxy

H. J. Osten; M. Czernohorsky; R. Dargis; A. Laha; D. Khne; E. Bugiel; A. Fissel

2007-09-01T23:59:59.000Z

91

Dudley Herschbach: Chemical Reactions and Molecular Beams  

NLE Websites -- All DOE Office Websites (Extended Search)

Dudley Herschbach: Dudley Herschbach: Chemical Reactions and Molecular Beams Resources with Additional Information Dudley Herschbach Courtesy of Texas A&M University As a co-recipient of the 1986 Nobel Prize in Chemistry, 'Dudley Herschbach was cited for "providing a much more detailed understanding of how chemical reactions take place". Using molecular beams, he studied elementary reactions such as K + CH3I and K + Br2, where it became possible to correlate reaction dynamics with the electronic structures of reactants and products. Exchanges proceeded through a persistent complex that lasted for many rotational periods, with product angular distributions reflecting the degree of reagent entanglement. Later this work was extended to H + Cl2, Cl + HI, halogen substitution reactions with vinyl and allyl halides, as well as such systems as Xe + Ar2 → XeAr + Ar. Herschbach has been a pioneer in the measurement and theoretical interpretation of vector properties of reaction dynamics, a field known as "molecular stereodynamics".

92

Research, Oxide Molecular Beam Epitaxy Group, Condensed Matter...  

NLE Websites -- All DOE Office Websites (Extended Search)

What is the nature of the superconducting transition? What is the role of charge stripes (if any) in the HTS state? What is the nature of the overdoped metallic state - a...

93

Publications, Oxide Molecular Beam Epitaxy Group, Condensed Matter Physics  

NLE Websites -- All DOE Office Websites (Extended Search)

Publications Publications In Press M. P. M. Dean, G. Dellea, R. S. Springell, F. Yakhou-Harris, K. Kummer, N. B. Brookes, X. Liu, Y. Sun, J. Strle, T. Schmitt, L. Braicovich, G. Ghiringhelli, I. Bozovic and J. P. Hill. "Persistence of magnetic excitations in La2-xSrxCuOP4 from the undoped insulator to the heavily overdoped non-superconducting metal." Nature Materials (Submitted 2013). In press. J. Wu, O. Pelleg, G. Logvenov, A. T. Bollinger, Y. Sun, G. S. Boebinger, M. Vanevic, Z. Radovic and I. Bozovic. "Anomalous (in)dependence of interface superconductivity on carrier density." Nature Materials (Submitted 2012). In press. G. Dubuis, A. T. Bollinger, D. Pavuna and I. Bozovic. "On Field Effect Studies and Superconductor-Insulator Transition in High-Tc Cuprates."

94

Laboratories, Oxide Molecular Beam Epitaxy Group, Condensed Matter Physics  

NLE Websites -- All DOE Office Websites (Extended Search)

Laboratories: Photo Tour Laboratories: Photo Tour MBE Laboratory MBE Laboratory MBE Chamber MBE Chamber Temperature Controllers MBE Computers and Servers Pneumatic Hoses Transport between MBE Laboratory and Nano-Lithography Laboratory Backside of MBE chamber during growth, lit by Nano-Lithography Laboratory Nano-Lithography Laboratory Processing Chamber Laminar Flow Hood Mask Aligner Profilometer Probe Station Wire Bonder X-Ray Diffraction and Chemistry Laboratory X-Ray Diffraction System X-Ray Diffraction System X-Ray Diffraction System Chemistry Laboratory Chemistry Laboratory Mutual Inductance, Transport and Field Effect Laboratory Field Effect Measurement system Liquid Helium-4 Dipstick for Mutual Inductance Transport Measurement System COMBI Hall Effect, COMBI Transport and Mutual Inductance Measurements Laboratory

95

Applied Super Conductor Group, Oxide Molecular Beam Epitaxy Group,  

NLE Websites -- All DOE Office Websites (Extended Search)

AEMG Homepage AEMG Homepage Site Details Homepage Research Publications Presentations Facilities How to Contact Us Other Information Basic Energy Sciences Directorate Links BNL Site Index Can't View PDFs? Advanced Energy Materials Group Applied Superconductivity The applied superconductivity research (past funded by DOE Office of Electricity Delivery and Energy Reliability) is related to modernization of the U.S. power grid. One direction of the modernization is replacement of normal metal (copper, aluminum) transmission lines with High Temperature Superconducting (HTS) cables. Our group concentrates its effort on studying fundamental thermodynamics of nucleation and texture development of thick YBCO layers. High-performance YBCO layer is a critical element of modern second generation (2G) HTS wire.

96

Oxide Molecular Beam Epitaxy Group, Condensed Matter Physics...  

NLE Websites -- All DOE Office Websites (Extended Search)

(right) and U.S. Under Secretary of Science Raymond L. Orbach (middle) visiting the MBE lab, 2 June 2006. Left: Ivan Bozovic. Back row: BNL Director Sam Aronson (right) and...

97

Visitors, Oxide Molecular Beam Epitaxy Group, Condensed Matter...  

NLE Websites -- All DOE Office Websites (Extended Search)

University) Mar 23 2009 Prof. Efthimios Liarokapis (Nat. Technical University, Athens, Greece) Mar 22 2009 to Mar 4 2009 Dr. Scott Riggs, Zac Stegen and Jon Kemper (Florida State...

98

Collaborations, Oxide Molecular Beam Epitaxy Group, Condensed Matter  

NLE Websites -- All DOE Office Websites (Extended Search)

Collaborations Collaborations Collaborations at BNL Experiment COBRA X-ray crystallography Researchers Dr. Ron Pindak, Dr. Hua Zhou (NSLS), Dr. Yitzak Yacobi (Technion, Israel) Object of Study The atomic structure of interfaces in M-I bilayers Experiment High-resolution electron microscopy Researchers Dr. Yimei Zhu (CMPMS) Object of Study The atomic structure of HTS heterostructures; bi-crystal grain boundaries Experiment Synchrotron X-ray crystallography Researchers Dr. John Hill (CMPMS) Object of Study Spin excitation spectrum in ultrathin LSCO layers Experiment Ultrafast electron diffraction Researchers Dr. Xijie Wang (NSLS) Object of Study Photo-induced lattice expansion Collaborations in the United States Experiment Resonant soft X-ray scattering (SXRS) Researchers Prof. Peter Abbamonte, Dr. Serban Smadici (University of Illinois at Urbana-Champaign)

99

Epitaxial growth of Dy2O3 thin films on epitaxial Dy-germanide films on Ge(001) substrates  

Science Conference Proceedings (OSTI)

Ultra-thin films of Dy are grown on Ge(001) substrates by molecular beam deposition near room temperature and immediately annealed for solid phase epitaxy at higher temperatures, leading to the formation of DyGe"x films. Thin films of Dy"2O"3 are grown ... Keywords: Dy2O3 film, Ge(001) substrate, High-? oxide, Molecular beam epitaxy (MBE), Structural characterization, Transmission electron microscopy (TEM)

Md. Nurul Kabir Bhuiyan; Mariela Menghini; Jin Won Seo; Jean-Pierre Locquet

2011-04-01T23:59:59.000Z

100

Integration of low dimensional crystalline Si into functional epitaxial oxides  

Science Conference Proceedings (OSTI)

In this work we show that by efficiently exploiting the growth kinetics during molecular beam epitaxy (MBE) one could create Si nanostructures of different dimensions. Examples are Si quantum dots (QD) or quantum wells (QW), which are buried into an ... Keywords: Epitaxial gadolinium oxide, Nonvolatile memories, Oxide-semiconductor-oxide quantum well, Resonant tunneling diode, Si quantum dots

Apurba Laha; E. Bugiel; R. Dargis; D. Schwendt; M. Badylevich; V. V. Afanas'ev; A. Stesmans; A. Fissel; H. J. Osten

2009-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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.


101

Molecular beam deposition of LaAlO3 on silicon for sub-22nm CMOS technological nodes: Towards a perfect control of the oxide/silicon heterointerface  

Science Conference Proceedings (OSTI)

This work reports on the development of thin amorphous LaAlO"3 (LAO) layers on Si(001) for their integration as gate oxide in sub-22nm CMOS technologies. The crucial influence of the Si surface preparation is highlighted and an optimized surface preparation ... Keywords: Amorphous high-? dielectrics, Interfacial layer, LaAlO3, Molecular beam epitaxy, Surface preparation

S. Pelloquin; L. Becerra; G. Saint-Girons; C. Plossu; N. Baboux; D. Albertini; G. Grenet; G. Hollinger

2009-07-01T23:59:59.000Z

102

Photoelectron spectroscopy of supersonic molecular beams  

DOE Green Energy (OSTI)

A new technique for performing high resolution molecular photoelectron spectroscopy is described, beginning with its conceptual development, through the construction of a prototypal apparatus, to the initial applications on a particularly favorable molecular system. The distinguishing features of this technique are: (1) the introduction of the sample in the form of a collimated supersonic molecular beam; and (2) the use of an electrostatic deflection energy analyzer which is carefully optimized in terms of sensitivity and resolution. This combination makes it possible to obtain photoelectron spectra at a new level of detail for many small molecules. Three experiments are described which rely on the capability to perform rotationally-resolved photoelectron spectroscopy on the hydrogen molecule and its isotopes. The first is a measurement of the ionic vibrational and rotational spectroscopic constants and the vibrationally-selected photoionization cross sections. The second is a determination of the photoelectron asymmetry parameter, ..beta.., for selected rotational transitions. The third is an investigation of the rotational relaxation in a free jet expansion, using photoelectron spectroscopy as a probe of the rotational state population distributions. In the closing chapter an assessment is made of the successes and limitations of the technique, and an indication is given of areas for further improvement in future spectrometers.

Pollard, J.E.

1982-05-01T23:59:59.000Z

103

A Combined Crossed Molecular Beams and Electronic Structure Study...  

NLE Websites -- All DOE Office Websites (Extended Search)

Combined Crossed Molecular Beams and Electronic Structure Study on the Gas Phase Formation of Prototype Aromatic and Polycyclic Aromatic Hydrocarbons (PAHs) Ralf I. Kaiser Dept....

104

Molecular beam surface analysis. 1993 Summary report  

SciTech Connect

The Molecular Beam Surface Analysis (MBSA) program is developing both laboratory-based and potentially field-portable chemical analyses systems taking advantage of new surface analysis technology developed at the Idaho National Engineering Laboratory (INEL). The objective is to develop the means to rapidly detect and identify, with high specificity and high sensitivity, nonvolatile and low volatile organics found in Chemical Weapons (CW) and High Explosives (HE) feedstocks, agents, and decomposition products on surfaces of plants, rocks, paint chips, filters, smears of buildings, vehicles, equipment, etc.. Ideally, the method would involve no sample preparation and no waste generation, and would have the potential for being implemented as a field-portable instrument. In contrast to existing analytical methods that rely on sample volatility, MBSA is optimized for nonvolatile and low volatile compounds. This makes it amenable for rapidly screening field samples for CW agent decomposition products and feedstock chemicals and perhaps actual agents. In its final configuration (benchtop size) it could be operated in a non-laboratory environment (such as an office building) requiring no sample preparation chemistry or chemical supplies. It could also be included in a mobile laboratory used in on-site, ore remote site cooperative surveys, or in a standard laboratory, where it would provide fast screening of samples at minimal cost.

Appelhans, A.D.; Ingram, J.C.; Groenewold, G.S.; Dahl, D.A.; Delmore, J.E.

1993-09-01T23:59:59.000Z

105

Epitaxial growth on gas cluster ion-beam processed GaSb substrates using molecular-beam epitaxy  

E-Print Network (OSTI)

cluster in a dual-energy recipe that included a moderate energy 10 keV etch step followed by a low-energy with the ever increasing demand for portable electronics, has pro- vided the semiconductor industry investigation as they operate at low supply voltages with- out sacrificing performance. Antimonide

Florida, University of

106

Molecular Beam Mass Spectrometry (MBMS) (Revised) (Fact Sheet)  

DOE Green Energy (OSTI)

This fact sheet provides information about Molecular Beam Mass Spectrometry (MBMS) capabilities and applications at NREL's National Bioenergy Center. NREL has six MBMS systems that researchers and industry partners can use to understand thermochemical biomass conversion and biomass composition recalcitrance.

Not Available

2011-07-01T23:59:59.000Z

107

Molecular-Beam Mass-Spectrometric Analyses of Hydrocarbon Flames.  

E-Print Network (OSTI)

??Laminar flat flame combustion has been studied with molecular-beam mass-spectrometry (MBMS) for a fuel-rich cyclohexane (? = 2.003) flame, a fuel-lean toluene (? = 0.895), (more)

Gon, Saugata

2008-01-01T23:59:59.000Z

108

Epitaxial EuO thin films on GaAs  

SciTech Connect

We demonstrate the epitaxial growth of EuO on GaAs by reactive molecular beam epitaxy. Thin films are grown in an adsorption-controlled regime with the aid of an MgO diffusion barrier. Despite the large lattice mismatch, it is shown that EuO grows well on MgO(001) with excellent magnetic properties. Epitaxy on GaAs is cube-on-cube and longitudinal magneto-optic Kerr effect measurements demonstrate a large Kerr rotation of 0.57 deg., a significant remanent magnetization, and a Curie temperature of 69 K.

Swartz, A. G.; Ciraldo, J.; Wong, J. J. I.; Li Yan; Han Wei; Lin Tao; Shi, J.; Kawakami, R. K. [Department of Physics and Astronomy, University of California, Riverside, California 92521 (United States); Mack, S.; Awschalom, D. D. [Center for Spintronics and Quantum Computation, University of California, Santa Barbara, California 93106 (United States)

2010-09-13T23:59:59.000Z

109

Yuan T. Lee and Molecular Beam Studies  

Office of Scientific and Technical Information (OSTI)

and the spectroscopy of ionic and molecular clusters. Lee was born in Hsinchu, Taiwan, China and as a youth experienced the adversity of WWII and Japanese occupation. At the war's...

110

CROSSED MOLECULAR BEAM STUDIES OF CHEMILUMINESCENT REACTIONS  

E-Print Network (OSTI)

L , and M. A. D. F1uendy, Chemic 1ecular Beam 12. A. KantrowP. R. Br J I I Lawley. Chemic al an and 1ey, Chern. I 5) were of brass and chemic Each lens ho 1 der consists of a

Kahler, Carol Cuzens

2013-01-01T23:59:59.000Z

111

Process for depositing an oxide epitaxially onto a silicon substrate and structures prepared with the process  

DOE Patents (OSTI)

A process and structure involving a silicon substrate utilizes an ultra high vacuum and molecular beam epitaxy (MBE) methods to grow an epitaxial oxide film upon a surface of the substrate. As the film is grown, the lattice of the compound formed at the silicon interface becomes stabilized, and a base layer comprised of an oxide having a sodium chloride-type lattice structure grows epitaxially upon the compound so as to cover the substrate surface. A perovskite may then be grown epitaxially upon the base layer to render a product which incorporates silicon, with its electronic capabilities, with a perovskite having technologically-significant properties of its own.

McKee, Rodney A. (Kingston, TN); Walker, Frederick J. (Oak Ridge, TN)

1993-01-01T23:59:59.000Z

112

Reactive Collisions in Crossed Molecular Beams  

DOE R&D Accomplishments (OSTI)

The distribution of velocity vectors of reaction products is discussed with emphasis on the restrictions imposed by the conservation laws. The recoil velocity that carries the products away from the center of mass shows how the energy of reaction is divided between internal excitation and translation. Similarly, the angular distributions, as viewed from the center of mass, reflect the partitioning of the total angular momentum between angular momenta of individual molecules and orbital angular momentum associated with their relative motion. Crossed-beam studies of several reactions of the type M + RI yields R + MI are described, where M = K, Rb, Cs, and R = CH{sub 3}, C{sub 3}H{sub 5}, etc. The results show that most of the energy of reaction goes into internal excitation of the products and that the angular distribution is quite anisotropic, with most of the MI recoiling backward (and R forward) with respect to the incoming K beam. (auth)

Herschbach, D. R.

1962-02-00T23:59:59.000Z

113

Silicon in functional epitaxial oxides: A new group of nanostructures  

Science Conference Proceedings (OSTI)

The ability to integrate low-dimensional crystalline silicon into crystalline insulators with high dielectric constant (high-k) can open the way for a variety of novel applications ranging from high-k replacement in future nonvolatile memory devices ... Keywords: Molecular beam epitaxy, Nanocluster, Nanostructures, Quantum well, Rare-earth oxides, Silicon

A. Fissel; A. Laha; E. Bugiel; D. Khne; M. Czernohorsky; R. Dargis; H. J. Osten

2008-03-01T23:59:59.000Z

114

Clusters and Magnetism in Epitaxial Co-doped TiO? Anatase.  

SciTech Connect

We show that under certain conditions, highly Co-enriched Ti0? anatase clusters nucleate on epitaxial Ti0? anatase grown on LaA?O?(001) by oxygen plasma assisted molecular beam epitaxy. In the most extreme cases, virtually all incident Co segregates to the clusters, yielding a nanoscale ferromagnitic phase that is not ferromagnetic in homogeneous films of the same Co concentration. The nucleation of this phase simultaneous with continuous epitaxial film growth must be carefully monitored in order to avoid drawing false conclusions about the film structure

Chambers, Scott A.; Droubay, Timothy; Wang, Chong M.; Lea, Alan S.; Farrow, R.F.C; Folks, L.; Deline, V.; Anders, S.

2003-02-24T23:59:59.000Z

115

Reactions of carbon atoms using crossed pulsed molecular beams  

DOE Green Energy (OSTI)

The development of efficient carbon atom sources was carried out concurrently with studying reactions 1--3, and we already have intriguing results concerning these reactions, even though the development phase is still in progress. Our goals are to study reactions of carbon atoms with hydrogen, hydrogen chloride, and nitrous oxide include correlations between the energy distributions of the fragments, branching ratios, and kinetic energy dependences. These studies will provide prototypical examples of insertion and abstraction reaction dynamics. We also hope to accomplish the development of laser ablation as a reliable and versatile source of radicals for pulsed molecular beam studies. 4 refs.

Reisler, H.

1989-04-01T23:59:59.000Z

116

Quantum wells on indium gallium arsenic compositionally graded buffers realized by molecular beam epitaxy  

E-Print Network (OSTI)

For a long time, there has been a desire to extend the emission wavelength of GaAs-based quantum well lasers, with the aim of eventually replacing InP with GaAs as the substrate of choice for communication applications. ...

Choy, Henry Kwong Hin, 1974-

2005-01-01T23:59:59.000Z

117

Polarized Emission from Single GaN Quantum Dots Grown by Molecular Beam Epitaxy  

Science Conference Proceedings (OSTI)

Polarization resolved microphotoluminescence measurements of single MBE-grown GaN/Al(Ga)N quantum dots (QDs) have been performed. The exciton and biexciton peaks with full width at half maximum as narrow as dots, resulting in different built-in electric field. Moreover, a strongly linearly polarized emission is observed for the investigated dots with a degree of linear polarization of about 0.9, interpreted as the valence-band mixing induced by in-plane anisotropy due to strain and/or QD shape.

Amloy, S. [Department of Physics, Chemistry, and Biology (IFM), Linkoeping University, S-58183 Linkoeping (Sweden); Department of Physics, Faculty of Science, Thaksin University, 93110 Phattalung (Thailand); Yu, K. H.; Karlsson, K. F.; Holtz, P. O. [Department of Physics, Chemistry, and Biology (IFM), Linkoeping University, S-58183 Linkoeping (Sweden); Farivar, R.; Andersson, T. G. [Applied Semiconductor Physics, Department of Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Goeteborg (Sweden)

2011-12-23T23:59:59.000Z

118

Atom probe tomography characterisation of a laser diode structure grown by molecular beam epitaxy  

E-Print Network (OSTI)

by the two techniques. 7 2. Experiment The LD structure wafer was grown using a Veeco V80 MBE system, on a commercially available ultra-low TD density template consisting of ~10 m of GaN grown by MOVPE on a sapphire substrate (Lumilog ULD template... of Europe to growth of the sample. SEB also thanks the Institute of Physics for the award of the annual Roy prize for a doctoral thesis on condensed matter and material physics, and the 20 Centre for Advanced Structural Ceramics for the award...

Bennett, Samantha; Smeeton, Tim; Saxey, David; Smith, George; Hooper, Stewart; Heffernan, Jonathan; Humphreys, Colin; Oliver, Rachel

2012-03-06T23:59:59.000Z

119

K1, Molecular Beam Epitaxy of Catalyst-Free InGaN/GaN Nanowires ...  

Science Conference Proceedings (OSTI)

I4, Electrical Spin Injection in a Hybrid Organic/Inorganic Spin-Polarized Light Emitting Diode (Spin-LED) I5, Properties of MnAs/GaMnAs/MnAs Magnetic...

120

Molecular beam epitaxy of SrTiO3 with a growth window  

E-Print Network (OSTI)

Estimated MBE growth window for SrTiO 3 in conventional MBEregion shows the growth window for stoichiometric films with4 (color online): Growth window for stoichiometric SrTiO 3

Stemmer, Susanne

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

Molecular-Beam Epitaxially Grown MgB2 Thin Films and Superconducting Tunnel Junctions  

E-Print Network (OSTI)

Since the discovery of its superconducting properties in 2001, magnesium diboride has generated terrific scientific and engineering research interest around the world. With a 𝑇

Laloe, Jean-Baptiste

122

EE3, Molecular Beam Epitaxy of Very Thin Fluoride Films on Ge(111)  

Science Conference Proceedings (OSTI)

RTDs were fabricated on Ge substrates by using the initial fluoride layer grown under the optimized condition. The various fluoride layers grown by the single...

123

LATE NEWS: L7, Molecular Beam Epitaxy of N-Polar InGaN  

Science Conference Proceedings (OSTI)

L6, PECVD-SiN, Si or Si/Al2O3-Capped ED-Mode AlN/GaN Inverters Hide details for [

124

Investigation of Spin-Based Phenomena in Candidate Spintronic Materials by Molecular Beam Epitaxy  

E-Print Network (OSTI)

211 10.2 Mg Distillation and MgO Homoepitaxy . . . . . .Distillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .213 10.2 Evolution of Mg Distillation. . . . . . . . . . . .

Swartz, Adrian

2013-01-01T23:59:59.000Z

125

Cerenkov emission induced by external beam radiation stimulates molecular fluorescence  

SciTech Connect

Purpose: Cerenkov emission is induced when a charged particle moves faster than the speed of light in a given medium. Both x-ray photons and electrons produce optical Cerenkov photons in everyday radiation therapy of tissue; yet, this phenomenon has never been fully documented. This study quantifies the emissions and also demonstrates that the Cerenkov emission can excite a fluorophore, protoporphyrin IX (PpIX), embedded in biological phantoms. Methods: In this study, Cerenkov emission induced by radiation from a clinical linear accelerator is investigated. Biological mimicking phantoms were irradiated with x-ray photons, with energies of 6 or 18 MV, or electrons at energies 6, 9, 12, 15, or 18 MeV. The Cerenkov emission and the induced molecular fluorescence were detected by a camera or a spectrometer equipped with a fiber optic cable. Results: It is shown that both x-ray photons and electrons, at MeV energies, produce optical Cerenkov photons in tissue mimicking media. Furthermore, we demonstrate that the Cerenkov emission can excite a fluorophore, protoporphyrin IX (PpIX), embedded in biological phantoms. Conclusions: The results here indicate that molecular fluorescence monitoring during external beam radiotherapy is possible.

Axelsson, Johan; Davis, Scott C.; Gladstone, David J.; Pogue, Brian W. [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States); Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766 (United States); Thayer School of Engineering and Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States)

2011-07-15T23:59:59.000Z

126

On the theory of energy distributions of products of molecular beam reactions involving transient complexes*  

E-Print Network (OSTI)

On the theory of energy distributions of products of molecular beam reactions involving transient October 1974) Theoretical energy distributions of reaction products in molecular beam systems for the energy distributions of the products when 1 > j and j > l. I. INTRODUCTION In recent years illuminating

Marcus, Rudolph A.

127

Growth of pseudomorphic structures through organic epitaxy  

SciTech Connect

The control of molecular orientation in thin solid film phases of organic semiconductors is a basic factor for the exploitation of their physical properties for optoelectronic devices. We compare structural and optical properties of thin films of the organic semiconductor {alpha}-quarterthiophene grown by molecular beam epitaxy on different organic substrates. We show how epitactic interactions, characteristic of the surface of organic crystals, can drive the orientation of the crystalline overlayer and the selection of specific polymorphs and new pseudomorphic phases. We identify a key role in this phenomenon played by the marked groove-like corrugations present in some organic crystal surfaces. Since different polymorphs possess rather different performance in terms of, e.g., charge carrier mobility, this strategy is demonstrated to allow for the growth of oriented phases with enhanced physical properties, while keeping the substrate at room temperature. These results provide useful guidelines for the design of technological substrates for organic epitaxy and they substantiate the adoption of an organic epitaxy approach for the fabrication of optoelectronic devices based on thin films of organic semiconductors.

Kaviyil, Sreejith Embekkat; Sassella, Adele; Borghesi, Alessandro [Department of Materials Science, Universita degli Studi di Milano Bicocca, Via R. Cozzi 53, I-20125 Milan (Italy); Campione, Marcello [Department of Earth and Environmental Sciences, Universita degli Studi di Milano Bicocca, Piazza della Scienza 4, I-20126 Milan (Italy); Su Genbo; He Youping [Fujian Institute of Research on the Structure of Matter, Chinese Academy of Science, Fuzhou 350002 (China); Chen Chenjia [Department of Physics, Peking University, Beijing 100871 (China)

2012-12-14T23:59:59.000Z

128

Internal Energy Dependence of Molecular Condensation Coefficients Determined from Molecular Beam Surface Scattering Experiments  

DOE R&D Accomplishments (OSTI)

An experiment was performed which confirms the existence of an internal mode dependence of molecular sticking probabilities for collisions of molecules with a cold surface. The scattering of a velocity selected effusive beam of CCl{sub 4} from a 90 K CC1{sub 4} ice surface has been studied at five translational velocities and for two different internal temperatures. At a surface temperature of 90 K (approx. 99% sticking probability) a four fold increase in reflected intensity was observed for the internally excited (560 K) CC1{sub 4} relative to the room temperature (298 K) CC1{sub 4} at a translational velocity of 2.5 X 10{sup 4} cm/sec. For a surface temperature of 90 K all angular distributions were found to peak 15{sup 0} superspecularly independent of incident velocity.

Sibener, S. J.; Lee, Y. T.

1978-05-00T23:59:59.000Z

129

Molecular Ion Beam Transportation for Low Energy Ion Implantation  

SciTech Connect

A joint research and development of steady state intense boron ion sources for 100's of electron-volt ion implanters has been in progress for the past five years. Current density limitation associated with extracting and transporting low energy ion beams result in lower beam currents that in turn adversely affects the process throughput. The transport channel with electrostatic lenses for decaborane (B{sub 10}H{sub 14}) and carborane (C{sub 2}B{sub 10}H{sub 12}) ion beams transportation was developed and investigated. The significant increase of ion beam intensity at the beam transport channel output is demonstrated. The transport channel simulation, construction and experimental results of ion beam transportation are presented.

Kulevoy, T. V.; Kropachev, G. N.; Seleznev, D. N.; Yakushin, P. E.; Kuibeda, R. P.; Kozlov, A. V.; Koshelev, V. A. [Institute for Theoretical and Experimental Physics, Moscow, 117218 (Russian Federation); Hershcovitch, A.; Johnson, B. M. [Brookhaven National Laboratory, Upton, New York 11973 (United States); Gushenets, V. I.; Oks, E. M. [High Current Electronics Institute Russian Academy of Sciences, Tomsk, 634055 (Russian Federation); Polozov, S. M. [Moscow Engineering Physics Institute, Kashirskoe sh. 31, Moscow, 115409 (Russian Federation); Poole, H. J. [PVI, Oxnard, California 93031-5023 (United States)

2011-01-07T23:59:59.000Z

130

Crossed molecular beam studies of atmospheric chemical reaction dynamics  

SciTech Connect

The dynamics of several elementary chemical reactions that are important in atmospheric chemistry are investigated. The reactive scattering of ground state chlorine or bromine atoms with ozone molecules and ground state chlorine atoms with nitrogen dioxide molecules is studied using a crossed molecular beams apparatus with a rotatable mass spectrometer detector. The Cl + O{sub 3} {yields} ClO + O{sub 2} reaction has been studied at four collision energies ranging from 6 kcal/mole to 32 kcal/mole. The derived product center-of-mass angular and translational energy distributions show that the reaction has a direct reaction mechanism and that there is a strong repulsion on the exit channel. The ClO product is sideways and forward scattered with respect to the Cl atom, and the translational energy release is large. The Cl atom is most likely to attack the terminal oxygen atom of the ozone molecule. The Br + O{sub 3} {yields} ClO + O{sub 2} reaction has been studied at five collision energies ranging from 5 kcal/mole to 26 kcal/mole. The derived product center-of-mass angular and translational energy distributions are quite similar to those in the Cl + O{sub 3} reaction. The Br + O{sub 3} reaction has a direct reaction mechanism similar to that of the Cl + O{sub 3} reaction. The electronic structure of the ozone molecule seems to play the central role in determining the reaction mechanism in atomic radical reactions with the ozone molecule. The Cl + NO{sub 2} {yields} ClO + NO reaction has been studied at three collision energies ranging from 10.6 kcal/mole to 22.4 kcal/mole. The center-of-mass angular distribution has some forward-backward symmetry, and the product translational energy release is quite large. The reaction proceeds through a short-lived complex whose lifetime is less than one rotational period. The experimental results seem to show that the Cl atom mainly attacks the oxygen atom instead of the nitrogen atom of the NO{sub 2} molecule.

Zhang, Jingsong

1993-04-01T23:59:59.000Z

131

Magnetism and transport properties of epitaxial Fe-Ga thin films on GaAs(001)  

SciTech Connect

Epitaxial Fe-Ga thin films in disordered bcc {alpha}-Fe crystal structure (A2) have been grown on GaAs(001) by molecular beam epitaxy. The saturated magnetization (M{sub S}) decreased from 1371 to 1105 kA/m with increasing Ga concentration from 10.5 to 24.3 % at room temperature. The lattice parameter increased with the increase in Ga content because of the larger atomic radius of Ga atom than that of Fe. The increase in carrier density with Ga content caused in lower resistivity.

Duong Anh Tuan; Shin, Yooleemi; Cho, Sunglae [Department of Physics, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Dang Duc Dung [Department of Physics, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Department of General Physics, School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi (Viet Nam); Vo Thanh Son [Centers for Nanobioenineering and Spintronics, Chungnam National University, Daejon 350-746 (Korea, Republic of)

2012-04-01T23:59:59.000Z

132

Molecular Beam Studies of Hot Atom Chemical Reactions: Reactive Scattering of Energetic Deuterium Atoms  

DOE R&D Accomplishments (OSTI)

A brief review of the application of the crossed molecular beams technique to the study of hot atom chemical reactions in the last twenty years is given. Specific emphasis is placed on recent advances in the use of photolytically produced energetic deuterium atoms in the study of the fundamental elementary reactions D + H{sub 2} -> DH + H and the substitution reaction D + C{sub 2}H{sub 2} -> C{sub 2}HD + H. Recent advances in uv laser and pulsed molecular beam techniques have made the detailed study of hydrogen atom reactions under single collision conditions possible.

Continetti, R. E.; Balko, B. A.; Lee, Y. T.

1989-02-00T23:59:59.000Z

133

Molecular beam studies of hot atom chemical reactions: Reactive scattering of energetic deuterium atoms  

DOE Green Energy (OSTI)

A brief review of the application of the crossed molecular beams technique to the study of hot atom chemical reactions in the last twenty years is given. Specific emphasis is placed on recent advances in the use of photolytically produced energetic deuterium atoms in the study of the fundamental elementary reactions D + H/sub 2/ /minus/> DH + H and the substitution reaction D + C/sub 2/H/sub 2/ /minus/> C/sub 2/HD + H. Recent advances in uv laser and pulsed molecular beam techniques have made the detailed study of hydrogen atom reactions under single collision conditions possible. 18 refs., 9 figs.

Continetti, R.E.; Balko, B.A.; Lee, Y.T.

1989-02-01T23:59:59.000Z

134

Structural controlled magnetic anisotropy in Heusler L1{sub 0}-MnGa epitaxial thin films  

Science Conference Proceedings (OSTI)

Ferromagnetic L1{sub 0}-MnGa thin films have been epitaxially grown on GaN, sapphire, and MgO substrates using molecular beam epitaxy. Using diffraction techniques, the epitaxial relationships are determined. It is found that the crystalline orientation of the films differ due to the influence of the substrate. By comparing the magnetic anisotropy to the structural properties, a clear correlation could be established indicating that the in-plane and out-of-plane anisotropy is directly determined by the crystal orientation of the film and could be controlled via selection of the substrates. This result could be helpful in tailoring magnetic anisotropy in thin films for spintronic applications.

Wang Kangkang; Lu Erdong; Smith, Arthur R. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Knepper, Jacob W.; Yang Fengyuan [Department of Physics, Ohio State University, 191 Woodruff Ave., Columbus, Ohio 43210 (United States)

2011-04-18T23:59:59.000Z

135

An ultra-thin buffer layer for Ge epitaxial layers on Si  

SciTech Connect

Using an Fe{sub 3}Si insertion layer, we study epitaxial growth of Ge layers on a Si substrate by a low-temperature molecular beam epitaxy technique. When we insert only a 10-nm-thick Fe{sub 3}Si layer in between Si and Ge, epitaxial Ge layers can be obtained on Si. The detailed structural characterizations reveal that a large lattice mismatch of {approx}4% is completely relaxed in the Fe{sub 3}Si layer. This means that the Fe{sub 3}Si layers can become ultra-thin buffer layers for Ge on Si. This method will give a way to realize a universal buffer layer for Ge, GaAs, and related devices on a Si platform.

Kawano, M.; Yamada, S.; Tanikawa, K.; Miyao, M.; Hamaya, K. [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan)] [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Sawano, K. [Advanced Research Laboratories, Tokyo City University, 8-15-1 Todoroki, Tokyo 158-0082 (Japan)] [Advanced Research Laboratories, Tokyo City University, 8-15-1 Todoroki, Tokyo 158-0082 (Japan)

2013-03-25T23:59:59.000Z

136

Crossed Molecular Beam Studies and Dynamics of Decomposition of Chemically Activated Radicals  

DOE R&D Accomplishments (OSTI)

The power of the crossed molecular beams method in the investigation of the dynamics of chemical reactions lies mainly in the direct observation of the consequences of single collisions of well controlled reactant molecules. The primary experimental observations which provide information on reaction dynamics are the measurements of angular and velocity distributions of reaction products.

Lee, Y. T.

1973-09-00T23:59:59.000Z

137

Production of a slit skimmer for use in cold supersonic molecular beams  

Science Conference Proceedings (OSTI)

Cold molecular beams generated by skimming pulsed supersonic gas expansions normally employ conical skimmers. The use of slit shaped skimmers instead of conical skimmers can afford significant signal enhancements. At this time, however, slit shaped skimmers are not available commercially. We describe a straightforward method for producing functional slit skimmers.

Subramanian, Ranga; Sulkes, Mark [Department of Chemistry, Tulane University, New Orleans, Louisiana 70118 (United States)

2008-01-15T23:59:59.000Z

138

Ultra-sensitive high-precision spectroscopy of a fast molecular ion beam  

Science Conference Proceedings (OSTI)

Direct spectroscopy of a fast molecular ion beam offers many advantages over competing techniques, including the generality of the approach to any molecular ion, the complete elimination of spectral confusion due to neutral molecules, and the mass identification of individual spectral lines. The major challenge is the intrinsic weakness of absorption or dispersion signals resulting from the relatively low number density of ions in the beam. Direct spectroscopy of an ion beam was pioneered by Saykally and co-workers in the late 1980s, but has not been attempted since that time. Here, we present the design and construction of an ion beam spectrometer with several improvements over the Saykally design. The ion beam and its characterization have been improved by adopting recent advances in electrostatic optics, along with a time-of-flight mass spectrometer that can be used simultaneously with optical spectroscopy. As a proof of concept, a noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) setup with a noise equivalent absorption of {approx}2 x 10{sup -11} cm{sup -1} Hz{sup -1/2} has been used to observe several transitions of the Meinel 1-0 band of N{sub 2}{sup +} with linewidths of {approx}120 MHz. An optical frequency comb has been used for absolute frequency calibration of transition frequencies to within {approx}8 MHz. This work represents the first direct spectroscopy of an electronic transition in an ion beam, and also represents a major step toward the development of routine infrared spectroscopy of rotationally cooled molecular ions.

Mills, Andrew A.; Siller, Brian M.; Porambo, Michael W.; Perera, Manori; Kreckel, Holger [Department of Chemistry, University of Illinois, Urbana, Illinois 61801 (United States); McCall, Benjamin J. [Department of Chemistry, University of Illinois, Urbana, Illinois 61801 (United States); Departments of Physics and Astronomy, University of Illinois, Urbana, Illinois 61801 (United States)

2011-12-14T23:59:59.000Z

139

Growth and structure of epitaxial Pb{sub 1-x}Mn{sub x}Se(Ga) films  

Science Conference Proceedings (OSTI)

The growth and structure of Pb{sub 1-x}Mn{sub x}Se (Ga) (N{sub Ga} = 0.8 at %) films with thicknesses of 0.3-0.5 {mu}m, grown on single-crystal PbSe{sub 1-x}S{sub x} (100) substrates by molecular-beam epitaxy, have been studied. It is established that films grow in a face-centered cubic lattice with the (100) orientation, reproducing the substrate orientation. The optimal conditions for obtaining photosensitive epitaxial films with perfect crystal structure are determined (W{sub 1/2} = 70-80'').

Nuriyev, I. R., E-mail: mhagiyev@yahoo.com; Gadzhiyev, M. B.; Sadigov, R. M. [National Academy of Sciences of Azerbaijan, Institute of Physics (Azerbaijan)

2009-03-15T23:59:59.000Z

140

Giant tunneling magnetoresistance up to 410% at room temperature in fully epitaxial Co/MgO/Co magnetic tunnel junctions with bcc Co(001) electrodes  

SciTech Connect

Fully epitaxial Co(001)/MgO(001)/Co(001) magnetic tunnel junctions (MTJs) with metastable bcc Co(001) electrodes were fabricated with molecular beam epitaxy. The MTJs exhibited giant magnetoresistance (MR) ratios up to 410% at room temperature, the highest value reported to date. Temperature dependence of the MR ratio was observed to be very small compared with fully epitaxial Fe/MgO/Fe and textured CoFeB/MgO/CoFeB MTJs. The MR ratio of the Co/MgO/Co MTJ showed larger bias voltage dependence than that of the epitaxial Fe/MgO/Fe MTJs, which probably reflects the band structures of bcc Co and Fe for the k{sub parallel}=0 direction.

Yuasa, Shinji; Fukushima, Akio; Kubota, Hitoshi; Suzuki, Yoshishige; Ando, Koji [National Institute of Advanced Industrial Science and Technology (AIST), Nanoelectronics Research Institute, Tsukuba, Ibaraki 305-8568 (Japan) and SORST, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012 (Japan); National Institute of Advanced Industrial Science and Technology (AIST), Nanoelectronics Research Institute, Tsukuba, Ibaraki 305-8568 (Japan)

2006-07-24T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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to obtain the most current and comprehensive results.


141

Molecular-beam, laser-rf, double-resonance studies of calcium monohalide radicals  

SciTech Connect

The molecular-beam, laser-rf, double-resonance technique has been described a number of times. In essence, the occurrence of a radiofrequency (rf) transition in the electronic ground state of the molecule under study is detected by an increase in the laser-induced fluorescence of the molecular beam when the rf is on resonance. The technique makes it possible to measure small energy splittings (normally spin-rotational or hyperfine) in the electronic ground state of a molecule to an absolute precision of 1 kHz. The sensitivity of the technique is high because even a very small increase in fluorescence can be easily seen if the rf is swept repeatedly and digital data-handling techniques are used. The technique is useful for ionic as well as for neutral atoms and molecules.

Childs, W.J.; Cok, D.R.; Goodman, L.S.

1981-01-01T23:59:59.000Z

142

Shape transitions and island nucleation for Si/Ge molecular beam epitaxy on stripe-patterned Si (001) substrate  

Science Conference Proceedings (OSTI)

Si and Ge growth on the stripe patterned Si (001) substrates is studied using scanning tunneling microscopy. During Si buffer growth, the stripe morphology rapidly evolves from multifaceted ''U'' to ''V''-shaped forms. This involves successive transitions between different low energy (11n) side facets, where n continuously decreases from n=3 to 20. Ge growth on such stripes induces the formation of a pronounced side wall ripple structure when the Ge thickness exceeds three monolayers. This ripple structure consists of alternating (105) microfacets oriented perpendicularly to the stripes. Depending of the side wall geometry, Ge nanoislands subsequently nucleate either on the side walls or at the bottom of grooves. The latter only occurs for ''V''-shaped stripes, where the side wall ripples extend all the way from the top to the bottom of the grooves, allowing efficient downward mass transport. For multifaceted ''U'' stripes, the side wall ripples are interrupted by steeper side wall segments such that mounds and subsequently, pyramids and domes grow on the side walls instead of at the bottom of the grooves. The island shapes strongly depend on their position on the pattern topography, which also affects the critical coverage for island nucleation as well as for the transition from pyramids to domes. The mechanisms for nucleation at different positions are clarified by detailed analysis and the role of kinetic as well as energetic factors identified.

Sanduijav, B.; Chen, G.; Springholz, G. [Institut fuer Halbleiter- und Festkoerperphysik, Johannes Kepler University, A-4040 Linz (Austria); Matei, D. [Institut fuer Halbleiter- und Festkoerperphysik, Johannes Kepler University, A-4040 Linz (Austria); National Institute for Laser, Plasma and Radiation Physics, RO-077125 Bucharest (Romania)

2009-09-15T23:59:59.000Z

143

Silicon sheet with molecular beam epitaxy for high efficiency solar cells. Final technical report, March 22, 1982-April 30, 1984  

DOE Green Energy (OSTI)

A two-year program has been carried out for the Jet Propulsion Laboratory in which the UCLA silicon MBE facility has been used to attempt to grow silicon solar cells of high efficiency. MBE ofers the potential of growing complex and arbitrary doping profiles with 10 A depth resolution. It is the only technique taht can readily grow built-in front and back surface fields of any desired depth and value in silicon solar cells, or the more complicated profiles needed for a double junction cascade cell, all in silicon, connected in series by a tunnel junction. Although the dopant control required for such structures has been demonstrated in silicon by UCLA, crystal quality at the p-n junctions is still too poor to allow the other advantages to be exploited. Results from other laboratories indicate that this problem will soon be overcome. A computer analysis of the double cascade all in silicon shows that efficiencies can be raised over that of any single silicon cell by 1 or 2%, and that open circuit voltage of almost twice that of a single cell should be possible.

Not Available

1984-01-01T23:59:59.000Z

144

Molecular beam epitaxy growth of GaAsBi/GaAs/AlGaAs separate confinement heterostructures  

Science Conference Proceedings (OSTI)

GaAsBi/GaAs/AlGaAs separate confinement heterostructures are grown using an asymmetric temperature profile due to the low optimal growth temperature of GaAsBi; the bottom AlGaAs barrier is grown at 610 Degree-Sign C, while the GaAsBi quantum well and the top AlGaAs barrier are grown at 320 Degree-Sign C. Cross-sectional transmission electron microscopy and room temperature photoluminescence measurements indicate that this approach results in samples with excellent structural and optical properties. The high quality of the low temperature AlGaAs barrier is attributed to the presence of Bi on the surface as indicated by a (1 Multiplication-Sign 3) surface reconstruction persisting throughout the low temperature growth.

Fan Dongsheng; Yu Shuiqing [Department of Electrical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Zeng Zhaoquan; Hu Xian; Dorogan, Vitaliy G.; Li Chen; Benamara, Mourad; Hawkridge, Michael E.; Mazur, Yuriy I.; Salamo, Gregory J. [Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Johnson, Shane R. [School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287-6206 (United States); Wang, Zhiming M. [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China)

2012-10-29T23:59:59.000Z

145

Growth of BGaAs by Molecular-Beam Epitaxy and the Effects of a Bismuth Surfactant  

DOE Green Energy (OSTI)

Boron is potentially useful for strain balancing compressively strained materials such as InGaAs and GaAsBi that are being developed for use in optical and electronic devices. Understanding and improving the incorporation of boron in GaAs is an important first step toward the realization of these strain-balanced systems. Here, we show that the apparent boron incorporation in GaAs, determined from X-ray diffraction measurements, decreases as the substrate temperature is increased, although measurements of the metallurgical concentration of boron remain constant. This implies that boron is incorporating preferentially on non-substitutional sites as growth temperature is increased. The addition of a bismuth surfactant flux not only makes the epilayers smoother, but within a narrow range of substrate temperatures, restores the incorporation of substitutional boron.

Ptak, A. J.; Beaton, D. A.; Mascarenhas, A.

2012-07-15T23:59:59.000Z

146

Growth of silicon(1-x) germanium(x) from disilane and digermane by gas-source molecular beam epitaxy.  

E-Print Network (OSTI)

??The growth rate R of Si(001), Ge(001), and rm Sisb{1-x}Gesb{x}(001) films deposited on Si(001)2 times 1 substrates from rm Sisb2Hsb6 and rm Gesb2Hsb6 by gas-source (more)

Bramblett, Thomas Richard

1994-01-01T23:59:59.000Z

147

Graphene Synthesis by Thermal Cracker Enhanced Gas Source Molecular Beam Epitaxy and Its Applications in Flash Memory  

E-Print Network (OSTI)

in growing large-area graphene on Co substrates. 3.5that nanocrystal based graphene memory is promising for97, 123105 Chapter 5: Graphene nano dots memory capacitor

Zhan, Ning

2011-01-01T23:59:59.000Z

148

Hot electron transmission in metals using epitaxial NiSi{sub 2}/n-Si(111) interfaces  

SciTech Connect

We have investigated hot electron transmission across epitaxial metal-disilicide/n-Si(111) interfaces using ballistic electron emission microscopy (BEEM). Different crystal orientations of epitaxial NiSi{sub 2} were grown on a Si(111) substrate using molecular beam epitaxy. The presence of different interfaces of NiSi{sub 2} on Si(111) were confirmed by high resolution transmission electron microscopy. Electrical transport measurements reveal a clear rectifying Schottky interface with a barrier height of 0.69 eV. However, using BEEM, three different regions with different transmissions and Schottky barrier heights of 0.65 eV, 0.78 eV, and 0.71 eV are found. The addition of a thin Ni film on the NiSi{sub 2} layer strongly reduces the transmission in all the three regions and interestingly, almost equalizes the transmission across them.

Parui, S.; Wit, B.; Wees, B. J. van; Banerjee, T. [Physics of Nanodevices, Zernike Institute for Advanced Materials, University of Groningen (Netherlands); Bignardi, L.; Rudolf, P. [Surfaces and Thin Films, Zernike Institute for Advanced Materials, University of Groningen (Netherlands); Kooi, B. [Nanostructured Materials and Interfaces, Zernike Institute for Advanced Materials, University of Groningen (Netherlands)

2011-07-18T23:59:59.000Z

149

The Controller Synthesis of Metastable Oxides Utilizing Epitaxy and Epitaxial Stabilization  

SciTech Connect

Molecular beam epitaxy (MBE) has achieved unparalleled control in the integration of semiconductors at the nanometer. These advances were made through the use of epitaxy, epitaxial stabilization, and a combination of composition-control techniques including adsorption-controlled growth and RHEED-based composition control that we have developed, understood, and utilized for the growth of oxides. Also key was extensive characterization (utilizing RHEED, four-circle x-ray diffraction, AFM, TEM, and electrical characterization techniques) in order to study growth modes, optimize growth conditions, and probe the structural, dielectric, and ferroelectric properties of the materials grown. The materials that we have successfully engineered include titanates (PbTiO3, Bi4Ti3O12), tantalates (SrBi2Ta2O9), and niobates (SrBi2Nb2O9); layered combinations of these perovskite-related materials (Bi4Ti3O12-SrTiO3 and Bi4Ti3O12-PbTiO3 Aurivillius phases and metastable PbTiO3/SrTiO3 and BaTiO3/SrTiO3 superlattices), and new metastable phases (Srn+1TinO3n+1 Ruddlesden-Popper phases). The films were grown by reactive MBE and pulsed laser deposition (PLD). Many of these materials are either new or have been synthesized with the highest perfection ever reported. The controlled synthesis of such layered oxide heterostructures offers great potential for tailoring the superconducting, ferroelectric, and dielectric properties of these materials. These properties are important for energy technologies.

Schlom, Darrell

2003-12-02T23:59:59.000Z

150

Molecular beams studies of the energetics and dynamics of elementary chemical reactions  

DOE Green Energy (OSTI)

Quantum mechanical effects on the angular distribution of HF products from the F + H/sub 2/ reaction were studied using crossed atomic and molecular beams with a rotatable mass spectrometer detector and time-of-flight velocity analysis. Measurement of the singlet-triplet splitting of CH/sub 2/ from the recoil velocities of fragments from ketene photodissociation in a molecular beam is also reported. Partial center-of-mass angular distributions, and velocity flux contour maps have been derived for individual vibrational states of the HF product from the F + H/sub 2/ reaction at collision energies of 2 and 3 kcal/mole. The center-of-mass distributions were obtained by analysis of laboratory angular and time-of-flight measurements of the reactive scattering. The results are consistent with recent three dimensional quantum mechanical scattering calculations, which predict that resonance effects should appear in the product angular distributions in this energy range. The photofragmentation of ketene in a molecular beam was used to measure the singlet-triplet splitting in CH/sub 2/. A rare gas halide excimer laser operating at 351 nm (XeF) and 308 nm (XeCl) dissociated the ketene. Time-of-flight measurements of the fragment velocities allowed determination of the energetics of the dissociation. The /sup 1/A/sub 1/ - /sup 3/B/sub 1/ splitting in CH/sub 2/ was found to be 8.5 +- 0.8 kcal/mole. This agrees with many experimental results, but not with the value of 19.5 kcal/mole derived from recent photodetachment experiments on CH/sub 2//sup -/.

Hayden, C.C.

1982-05-01T23:59:59.000Z

151

Lattice-matched epitaxial GaInAsSb/GaSb thermophotovoltaic devices  

DOE Green Energy (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

152

Process for depositing epitaxial alkaline earth oxide onto a substrate and structures prepared with the process  

Science Conference Proceedings (OSTI)

A process and structure involving a silicon substrate utilize molecular beam epitaxy (MBE) and/or electron beam evaporation methods and an ultra-high vacuum facility to grow a layup of epitaxial alkaline earth oxide films upon the substrate surface. By selecting metal constituents for the oxides and in the appropriate proportions so that the lattice parameter of each oxide grown closely approximates that of the substrate or base layer upon which oxide is grown, lattice strain at the film/film or film/substrate interface of adjacent films is appreciably reduced or relieved. Moreover, by selecting constituents for the oxides so that the lattice parameters of the materials of adjacent oxide films either increase or decrease in size from one parameter to another parameter, a graded layup of films can be grown (with reduced strain levels therebetween) so that the outer film has a lattice parameter which closely approximates that of, and thus accomodates the epitaxial growth of, a pervoskite chosen to be grown upon the outer film.

McKee, Rodney A. (Kingston, TN); Walker, Frederick J. (Oak Ridge, TN)

1996-01-01T23:59:59.000Z

153

Adsorption of iso-/n-butane on an Anatase Thin Film: A Molecular Beam Scattering and TDS Study  

SciTech Connect

Binding energies and adsorption probabilities have been determined for n/iso-butane adsorption on an anatase thin film grown on SrTiO3(001) by means of thermal desorption spectroscopy (TDS) and molecular beam scattering. The sample has been characterized by x-ray diffraction (XRD) and Auger electrons spectroscopy (AES).

Goering, J.; Kadossov, E.; Burghaus, Uwe; Yu, Zhongqing; Thevuthasan, Suntharampillai; Saraf, Laxmikant V.

2007-07-01T23:59:59.000Z

154

Homobuffer thickness effect on the background electron carrier concentration of epitaxial ZnO thin films  

Science Conference Proceedings (OSTI)

Epitaxial ZnO thin films were grown on r-plane sapphire substrates using plasma-assisted molecular-beam epitaxy. ZnO homobuffer layers grown at a lower temperature were introduced to improve the crystallinity of the top ZnO thin films. Thicker homobuffer layers lead to better crystallinity of the subsequent epitaxial ZnO thin films due to the strain relaxation effect. Residual background electron carrier concentration in these undoped ZnO thin films first decreases, then increases as the buffer layer thickness increases from {approx}1 to 30 nm, with a minimum electron concentration of {approx}1x10{sup 17} cm{sup -3} occurring in ZnO homobuffer of {approx}5 nm. These results demonstrate that the optimized ZnO homobuffer thickness to achieve both good ZnO crystallinity and low residual electron concentration is determined by the relative electron carrier concentration ratios and mobility ratios between the buffer and epi-ZnO layers.

Yang, Z.; Zhou, H. M.; Li, L.; Zhao, J. Z.; Liu, J. L. [Department of Electrical Engineering, Quantum Structures Laboratory, University of California, Riverside, California 92521 (United States); Chen, W. V.; Yu, P. K. L. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

2010-09-15T23:59:59.000Z

155

Crossed molecular beams study of O({sup 1}D) reactions with H{sub 2} molecules  

DOE Green Energy (OSTI)

Reaction dynamics of O({sup 1}D) atoms with H{sub 2} molecules was reinvestigated using the crossed molecular beams technique with pulsed beams. The O({sup 1}D) beam was generated by photodissociating O{sub 3} molecules at 248 nm. Time-of-flight spectra and the laboratory angular distribution of the OH products were measured. The derived OH product center-of-mass flux-velocity contour diagram shows more backward scattered intensity with respect to the O({sup 1}D) beam. In contrast to previous studies which show that the insertion mechanism is the dominant process, our results indicate that the contribution from the collinear approach of the O({sup 1}D) atom to the H{sub 2} molecule on the first excited state potential energy surface is significant and the energy barrier for the collinear approach is therefore minimal. Despite the increased time resolution in this experiment, no vibrational structure in the OH product time-of-flight spectra was resolved. This is in agreement with LIF studies, which have shown that the rotational distributions of the OH products in all vibrational states are broad and highly inverted.

Miau, T.T.

1995-05-01T23:59:59.000Z

156

Chemical nature of the passivation layer depending on the oxidizing agent in Gd2O3/GeO2/Ge stacks grown by molecular beam deposition  

Science Conference Proceedings (OSTI)

In Ge-based metal oxide semiconductor technology, the insertion of a passivation layer seems to be crucial in unpinning the Fermi level at the interface and in reducing the amount of interface defects. GeO"2 was obtained by atomic oxygen (AO), molecular ... Keywords: Gadolinium oxide, Germanium, Molecular beam deposition, Passivation layer, Time-of-flight secondary ion mass spectrometry

A. Lamperti; S. Baldovino; A. Molle; M. Fanciulli

2011-04-01T23:59:59.000Z

157

Structure and features of the surface morphology of A{sup 4}B{sup 6} chalcogenide epitaxial films  

Science Conference Proceedings (OSTI)

The structure and features of the surface morphology of Pb{sub 1-x}Mn{sub x}Se (x = 0.03) epitaxial films grown on freshly cleaved BaF{sub 2}(111) faces and PbSe{sub 1-x}S{sub x}(100) (x = 0.12) single-crystal wafers were investigated by molecular beam condensation and the hot-wall method. It is shown that the epitaxial films, in accordance with the data in the literature for other chalcogenides, grow in the (111) and (100) planes, repeating the substrate orientation. Black aggregates are observed on the film surface of the films grown. The results obtained are compared with the data in the literature and generalized for other chalcogenides: A{sup 4}B{sup 6}:Pb (S, Se, Te); Pb{sub 1-x}Sn{sub x} (S, Se, Te); and Pb{sub 1-x}Mn (Se, Te). It is established that the formation of black aggregates, which are second-phase inclusions on the surface of epitaxial films obtained by vacuum thermal deposition, is characteristic of narrow-gap A{sup 4}B{sup 6} chalcogenides.

Nuriyev, I. R., E-mail: afinnazarov@yahoo.com [Azerbaijan National Academy of Sciences, Institute of Physics (Azerbaijan)

2009-12-15T23:59:59.000Z

158

Robust surface electronic properties of topological insulators: Bi{sub 2}Te{sub 3} films grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

The surface electronic properties of the important topological insulator Bi{sub 2}Te{sub 3} are shown to be robust under an extended surface preparation procedure, which includes exposure to atmosphere and subsequent cleaning and recrystallization by an optimized in situ sputter-anneal procedure under ultrahigh vacuum conditions. Clear Dirac-cone features are displayed in high-resolution angle-resolved photoemission spectra from the resulting samples, indicating remarkable insensitivity of the topological surface state to cleaning-induced surface roughness.

Plucinski, L.; Herdt, A. [Peter Gruenberg Institut (PGI-6), Forschungszentrum Juelich, D-52425 Juelich (Germany); Mussler, G.; Krumrain, J.; Gruetzmacher, D. [Peter Gruenberg Institut (PGI-9), Forschungszentrum Juelich, D-52425 Juelich (Germany); Juelich Aachen Research Alliance-Fundamentals of Future Information Technologies (JARA-FIT), D-52425 Juelich (Germany); Suga, S. [Peter Gruenberg Institut (PGI-6), Forschungszentrum Juelich, D-52425 Juelich (Germany); Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Schneider, C. M. [Peter Gruenberg Institut (PGI-6), Forschungszentrum Juelich, D-52425 Juelich (Germany); Juelich Aachen Research Alliance-Fundamentals of Future Information Technologies (JARA-FIT), D-52425 Juelich (Germany)

2011-05-30T23:59:59.000Z

159

The effect of encapsulation on the morphology and chemical composition of InAs/GaAs quantum dots grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

In order to fabricate an effective device structure based on InAs quantum dots (QDs), the QD layers must be encapsulated within a matrix that has a wider band gap. This encapsulation is usually achieved by the overgrowth of GaAs. Coherent strained InAs/GaAs ... Keywords: encapsulation, indium arsenide, quantum dots, transmission electron microscopy

D. Zhi; M. Wei; R. E. Dunin-Borkowski; P. A. Midgley; D. W. Pashley; T. S. Jones; B. A. Joyce; P. F. Fewster; P. J. Goodhew

2004-06-01T23:59:59.000Z

160

Ga{sub 1-x}Mn{sub x}N epitaxial films with high magnetization  

Science Conference Proceedings (OSTI)

We report on the fabrication of pseudomorphic wurtzite Ga{sub 1-x}Mn{sub x}N grown on GaN with Mn concentrations up to 10% using molecular beam epitaxy. According to Rutherford backscattering, the Mn ions are mainly at the Ga-substitutional positions, and they are homogeneously distributed according to depth-resolved Auger-electron spectroscopy and secondary-ion mass-spectroscopy measurements. A random Mn distribution is indicated by transmission electron microscopy, and no Mn-rich clusters are present for optimized growth conditions. A linear increase of the c-lattice parameter with increasing Mn concentration is found using x-ray diffraction. The ferromagnetic behavior is confirmed by superconducting quantum-interference measurements showing saturation magnetizations of up to 150 emu/cm{sup 3}.

Kunert, G.; Kruse, C.; Figge, S.; Hommel, D. [Semiconductor Epitaxy, Institute of Solid State Physics, University of Bremen, D-28359 Bremen (Germany); Dobkowska, S.; Jakiela, R.; Stefanowicz, W.; Sawicki, M. [Institute of Physics, Polish Academy of Science, PL-02-668 Warszawa (Poland); Li, Tian; Bonanni, A. [Institute for Semiconductor and Solid State Physics, Johannes Kepler University Linz, A 4040 Linz (Austria); Reuther, H.; Grenzer, J.; Borany, J. von [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, 01328 Dresden (Germany); Dietl, T. [Institute of Physics, Polish Academy of Science, PL-02-668 Warszawa (Poland); Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, PL-00-681 Warszawa (Poland)

2012-07-09T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

Molecular Beam Dumps as Tracers of Hadronic Cosmic Ray Sources: the Case of SNR IC443  

E-Print Network (OSTI)

The gamma-ray & neutrino visibility of cosmic ray (CR) accelerators will be dramatically increased by the presence of molecular material abutting such sites due to the increased probability of pion production -- and, in the case of neutral pions, subsequent gamma-decay. This was recognized by Pinkau, Montmerle, and Black & Fazio, and others in the 1970's. In an effort to examine the long-standing -- but unproven -- conjecture that galactic supernova remnants (SNRs) are indeed the sites of nucleonic CR acceleration to Hartman et al.,1999), and molecular clouds, at low Galactic latitudes (|b|0) mm wavelength data from the compilation of Dame, Hartmann & Thaddeus (2001), at the best estimates of the various SNR distances. We outline the overall correlative study and examine the interesting case of SNR IC443, a likely accelerator of CR nuclei.

Yousaf M. Butt; Diego F. Torres; Jorge A. Combi; Thomas M. Dame; Gustavo E. Romero

2002-06-09T23:59:59.000Z

162

Interface and Electronic Characterization of Thin Epitaxial Co3O4 Films  

Science Conference Proceedings (OSTI)

The interface and electronic structure of thin ({approx} 20-74 nm) Co{sub 3}O{sub 4}(1 1 0) epitaxial films grown by oxygen-assisted molecular beam epitaxy on MgAl{sub 2}O{sub 4}(1 1 0) single crystal substrates have been investigated by means of real and reciprocal space techniques. As-grown film surfaces are found to be relatively disordered and exhibit an oblique low energy electron diffraction (LEED) pattern associated with the O-rich CoO{sub 2} bulk termination of the (1 1 0) surface. Interface and bulk film structure are found to improve significantly with post-growth annealing at 820 K in air and display sharp rectangular LEED patterns, suggesting a surface stoichiometry of the alternative Co{sub 2}O{sub 2} bulk termination of the (1 1 0) surface. Non-contact atomic force microscopy demonstrates the presence of wide terraces separated by atomic steps in the annealed films that are not present in the as-grown structures; the step height of {approx}2.7 {angstrom} corresponds to two atomic layers and confirms a single termination for the annealed films, consistent with the LEED results. A model of the (1 x 1) surfaces that allows for compensation of the polar surfaces is presented.

Vaz, C.A.; Zhu, Y.; Wang, H.-Q.; Ahn, C.H.; Henrich, V.E.; Baykara, M.Z.; Schwendemann, T.C.; Pilet, N.; Albers, B.J.; Schwarz, U.D.; Zhang, L.H,; Wang, J.; Altman, E.I.

2009-01-15T23:59:59.000Z

163

Molecular Beam Dumps as Tracers of Hadronic Cosmic Ray Sources the Case of SNR IC443  

E-Print Network (OSTI)

The gamma-ray & neutrino visibility of cosmic ray (CR) accelerators will be dramatically increased by the presence of molecular material abutting such sites due to the increased probability of pion production -- and, in the case of neutral pions, subsequent gamma-decay. This was recognized by Pinkau, Montmerle, and Black & Fazio, and others in the 1970's. In an effort to examine the long-standing -- but unproven -- conjecture that galactic supernova remnants (SNRs) are indeed the sites of nucleonic CR acceleration to 0) mm wavelength data from the compilation of Dame, Hartmann & Thaddeus (2001), at the best estimates of the various SNR distances. We outline the overall correlative study and examine the interesting case of SNR IC443, a likely accelerator of CR nuclei.

Butt, Y M; Combi, J A; Dame, T M; Romero, G E; Butt, Yousaf M.; Torres, Diego F.; Combi, Jorge A.; Dame, Thomas; Romero, Gustavo E.

2002-01-01T23:59:59.000Z

164

Growth and structure of photosensitive Pb{sub 1-x}Mn{sub x}Te(Ga) epitaxial films  

Science Conference Proceedings (OSTI)

The growth and structure of (1-1.5)-{mu}m-thick Pb{sub 1-x}Mn{sub x}Te(Ga)(x = 0.06) films with 0.4-0.9 at % of gallium, grown on BaF{sub 2}(111) and Pb{sub 1-x}Sn{sub x}Te (x = 0.2) (100) substrates by molecular beam epitaxy, have been investigated. It is established that the films are crystallized into an fcc structure, and their growth planes are (111) and (100), according to the substrate orientation. The optimal conditions for obtaining high-resistivity photosensitive p-and n-type films with a perfect crystal structure (W{sub 1/2} = 80''-100'') have been determined.

Nuriev, I. R.; Sadygov, R. M.; Nazarov, A. M., E-mail: afinnazarov@yahoo.com [Azerbaijan National Academy of Sciences, Institute of Physics (Azerbaijan)

2008-05-15T23:59:59.000Z

165

Magnetic behaviour of europium epitaxial thin films  

Science Conference Proceedings (OSTI)

... Magnetic behaviour of europium epitaxial thin films. Philippe Mangin, University of Nancy and NCNR. We present the magnetic ...

166

Epitaxial Graphene: Designing a New Electronic Material  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, 2010 Electronic Materials Conference. Symposium, TMS 2010 Electronic Materials Conference. Presentation Title, Epitaxial...

167

Understanding controls on interfacial wetting at epitaxial graphene: Experiment and Theory  

SciTech Connect

The interaction of interfacial water with graphitic carbon at the atomic scale is studied as a function of the hydrophobicity of epitaxial graphene. High resolution x-ray reflectivity shows that the graphene-water contact angle is controlled by the average graphene thickness, due to the fraction of the film surface expressed as the epitaxial buffer layer whose contact angle (contact angle c = 73 ) is substantially smaller than that of multilayer graphene ( c = 93 ). Classical and ab initio molecular dynamics simulations show that the reduced contact angle of the buffer layer is due to both its epitaxy with the SiC substrate and the presence of interfacial defects. This insight clarifies the relationship between interfacial water structure and hydrophobicity, in general, and suggests new routes to control interface properties of epitaxial graphene.

Zhou, Hua [Argonne National Laboratory (ANL); Ganesh, Panchapakesan [ORNL; Presser, Volker [Drexel University; Wander, Matthew C [ORNL; Fenter, Paul [Argonne National Laboratory (ANL); Kent, Paul R [ORNL; Jiang, Deen [ORNL; Chialvo, Ariel A [ORNL; Mcdonough, John [Drexel University; Shuford, Kevin L [ORNL; Gogotsi, Yury G. [Drexel University

2012-01-01T23:59:59.000Z

168

Aberration corrected scanning transmission electron microscopy and electron energy loss spectroscopy studies of epitaxial Fe/MgO/(001)Ge heterostructures  

SciTech Connect

Aberration correction in the scanning transmission electron microscope combined with electron energy loss spectroscopy allows simultaneous mapping of the structure, the chemistry and even the electronic properties of materials in one single experiment with spatial resolutions of the order of one Angstrom. Here the authors will apply these techniques to the characterization of epitaxial Fe/MgO/(001)Ge and interfaces with possible applications for tunneling junctions, and the authors will show that epitaxial MgO films can be grown on a (001)Ge substrates by molecular beam epitaxy and how it is possible to map the chemistry of interfaces with atomic resolution. Epitaxial growth of insulator oxides on semiconductors constitutes a key issue within the field of electronics, and a considerably large effort has been devoted to harness the growth of high-k oxides on Si. Ge, due to its high electronic and hole mobility, is a very interesting alternative as a potential substrate for future high performance complementary metal-oxide-semiconductor field-effect transistors. However, a major issue is to avoid the high resistivity at the source and drain contacts ensuing from the pinning of the Fermi level at the valence-band maximum. It has been suggested that this problem could be fixed by depositing a thin insulating tunneling barrier between the Ge substrate and the metal contacts. In this case, single crystal epitaxy would represent an additional benefit, since it would lead to a reduction of interfacial defects and improved performance of the tunneling barrier. MgO has been suggested to fulfill such requisites. Furthermore, MgO has been demonstrated to be a good substrate for epitaxial growth of transition metals thin films, such as Fe and Co, thus avoiding the potential problem of chemical reactivity with Ge. In such a scenario, epitaxial deposition of high quality MgO films on Ge substrates is highly desirable. But in addition, successful epitaxial growth of MgO on a semiconductor would also constitute a plus for applications in spintronics, since the injection of a spin polarized current from a ferromagnetic electrode to a non-magnetic semiconductor requires the presence of a potential barrier. MgO represents a convenient choice because the symmetry filtering properties at the interface with transition metals would allow an efficient spin filtering effect. For this approach to succeed, a suitable semiconducting substrate where MgO can be grown epitaxially must be found. And again, while GaAs and Si have been investigated for such role, Ge has not received much attention so far. In this study the authors report on the atomic resolution characterization of high quality interfaces in Fe/MgO/(001)Ge heterostructures. The study of the defects, the inhomogeneities and the interface structure of such junctions is a must to pave the way toward future applications. For this aim, the combination of scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) is a most useful tool, since it allows these features to be probed with atomic resolution. Spherical aberration correction in the STEM allows for increased contrast, allowing even single atoms to be detected both in imaging and spectroscopy.

Gazquez Alabart, Jaume [ORNL; Varela del Arco, Maria [ORNL; Petti, D. [Politecnico di Milano; Cantoni, M. [Politecnico di Milano; Rinaldi, C. [Politecnico di Milano; Brivio, S. [Politecnico di Milano; Bertacco, R. [Politecnico di Milano

2011-01-01T23:59:59.000Z

169

Hyperfine and spin--rotational structure of CaBr X /sup 2/. sigma. (v = 0) by molecular-beam laser-rf double resonance  

SciTech Connect

The molecular-beam, laser--rf, double-resonance technique has been used to make high-precision measurements of the spin--rotation and hyperfine interactions in the X /sup 2/..sigma.. (v = 0) electronic ground state of Ca/sup 79/Br and Ca/sup 81/Br. The spin--rotation interaction is found to have a strong N dependence. The Frosch--Foley magnetic hyperfine parameters b and c and the electric--quadrupole hfs parameter eqQ are determined for both molecules.

Childs, W.J.; Cok, D.R.; Goodman, G.L.; Goodman, L.S.

1981-07-15T23:59:59.000Z

170

Cubic GaN Light Emitting Diode Grown by Metalorganic Vapor-Phase Epitaxy  

E-Print Network (OSTI)

this paper, we report on the doping characteristics of Si and Mg in the growth of cubic GaN by metalorganic vapor-phase epitaxy (MOVPE). We also report the growth of a p-n diode structure made of cubic GaN, and its characterization by electron-beam-induced-current (EBIC) and current injection measurements.

Hidenao Tanaka Member; Vapor-phase Epitaxy; Atsushi Nakadaira

2000-01-01T23:59:59.000Z

171

X-ray reciprocal space mapping of dislocation-mediated strain relaxation during InGaAs/GaAs(001) epitaxial growth  

Science Conference Proceedings (OSTI)

Dislocation-mediated strain relaxation during lattice-mismatched InGaAs/GaAs(001) heteroepitaxy was studied through in situ x-ray reciprocal space mapping (in situ RSM). At the synchrotron radiation facility SPring-8, a hybrid system of molecular beam epitaxy and x-ray diffractometry with a two-dimensional detector enabled us to perform in situ RSM at high-speed and high-resolution. Using this experimental setup, four results in terms of film properties were simultaneously extracted as functions of film thickness. These were the lattice constants, the diffraction broadenings along in-plane and out-of-plane directions, and the diffuse scattering. Based on correlations among these results, the strain relaxation processes were classified into four thickness ranges with different dislocation behavior. In addition, the existence of transition regimes between the thickness ranges was identified. Finally, the dominant dislocation behavior corresponding to each of the four thickness ranges and transition regimes was noted.

Sasaki, Takuo; Ohshita, Yoshio; Kamiya, Itaru; Yamaguchi, Masafumi [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku-ku, Nagoya 468-8511 (Japan); Suzuki, Hidetoshi [University of Miyazaki, 1-1 Gakuen, Kibanadai-nishi, Miyazaki 889-2154 (Japan); Takahasi, Masamitu [Japan Atomic Energy Agency, 1-1-1 Koto, Sayo, Hyogo 679-5148 (Japan)

2011-12-01T23:59:59.000Z

172

XAFS Study of Epitaxial CoxTi1-xO?-x Anatase  

SciTech Connect

Co doped TiO?-anatase is a promising candidate for a room-temperature ferromagnetic semiconductor. XAFS measurements have been used to investigate the local Co environment and Co valence for several Co-anatase films. The samples were grown on LaAlO?(001) by oxygen plasma assisted molecular beam epitaxy and on SrTiO? by atomic oxygen assisted MBE. Co concentrations were about 5%. The measurements were made at the PNC-CAT bending magnet and undulator beamlines at the Advanced Photon Source. For the films on LaAlO?, the near edge clearly shows the presence of only Co(??), and no evidence for metallic Co, while the films on SrTiO? showed significant metallic Co. Analysis of the extended fine structure for the LaAlO? films finds that the Co substitutes for Ti with some distortion of the lattice. Both in-plane and out-of-plane Co-O bonds are expanded from the Ti-O bonds in anatase. The in-plane bonds are expanded approximately twice as much. A deficit in the oxygen coordination number suggests a correlation of oxygen vacancies with Co sites.

Heald, Steve M.; Chambers, Scott A.; Droubay, Timothy

2005-01-01T23:59:59.000Z

173

Local Co Structure in Epitaxial Cox Ti?-xO?-x Anatase  

SciTech Connect

The quest for diluted magnetic semiconductors (DMS) which retain their magnetism at and above room temperature is spanning several classes of materials. Such materials are critically important in the development of spintronics as spin injectors for semiconductor heterostructures that can operate without cryogenic cooling. Group IV, III-V, and II-VI DMS materials typically exhibit Curie temperatures (Tc) well below ambient due to weak interaction of the magnetic impurities. Calculations based on the Zener model of magnetism suggest that the strongest interaction is that mediated by holes, and experimental studies carried out to date have borne out this prediciton. One notable exception is that of Mn-doped GaN, which grows n-type by gas-source molecular beam epitaxy under certain conditions, and appears to be ferromagnetic at room temperature. In addition, it has recently been shown that at least one oxide semiconductor - Co-doped TiO? anatase or CoxTi?-xO?-x - is ferromagnetic well above room temperature when doped n-type by oxygen vacancies for x < ~0.1, but the mechanism of magnetism remains unknown.

Chambers, Scott A.; Heald, Steve M.; Droubay, Timothy

2003-03-01T23:59:59.000Z

174

Epitaxial growth on silicon and characterization of MnF{sub 2} and ZnF{sub 2} layers with metastable orthorhombic structure  

SciTech Connect

The growth of MnF{sub 2} and ZnF{sub 2} layers on Si(001) and Si(111) substrates was studied by molecular-beam epitaxy. Calcium fluoride buffer layers with (001) (110), and (111) orientations were used to prevent chemical interaction of MnF{sub 2} and ZnF{sub 2} molecules with the Si substrate. The analysis of x-ray and reflection high-energy electron-diffraction (RHEED) patterns showed that MnF{sub 2} layers grow on all of these planes in the orthorhombic {alpha}-PbO{sub 2}-type crystal phase observed earlier only at high pressures and temperatures. Atomic force microscopy revealed a strong dependence of the surface morphology on the buffer orientation and growth temperature. The best-ordered MnF{sub 2} growth occurred at 500 deg. C on a CaF{sub 2} (110) buffer layer. The diffraction analysis enabled us to find the epitaxial relations at the MnF{sub 2}/CaF{sub 2} interface. A careful analysis of the RHEED patterns of the films grown on CaF{sub 2}(001) showed a similarity in the structure and growth modes between MnF{sub 2} and ZnF{sub 2} layers, with ZnF{sub 2} tending to form multiphase layers. These findings are in agreement with the x-ray diffraction measurements.

Kaveev, A.K.; Anisimov, O.V.; Banshchikov, A.G.; Kartenko, N.F.; Ulin, V.P.; Sokolov, N.S. [Ioffe Physico-Technical Institute Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation)

2005-07-01T23:59:59.000Z

175

Influence of growth rate on the epitaxial orientation and crystalline quality of CeO2 thin films grown on Al2O3(0001)  

SciTech Connect

Growth rate-induced epitaxial orientations and crystalline quality of CeO2 thin films grown on Al2O3(0001) by oxygen plasma-assisted molecular beam epitaxy were studied using in-situ and ex-situ characterization techniques. CeO2 grows as three-dimensional (3-D) islands and two-dimensional (2-D) layers at growth rates of 1-7 /min, and ?9 /min, respectively. The formation of epitaxial CeO2(100) and CeO2(111) thin films occurs at growth rates of 1 /min and ? 9 /min, respectively. Glancing incidence x-ray diffraction (GIXRD) measurements have shown that the films grown at intermediate growth rates (2-7 /min) consist of polycrystalline CeO2 along with CeO2(100). The thin film grown at 1 /min exhibits six in-plane domains, characteristic of well-aligned CeO2(100) crystallites. The content of the poorly-aligned CeO2(100) crystallites increases with increasing growth rate from 2 /min to 7 /min, and three out of six in-plane domains gradually decrease and eventually disappear, as confirmed by XRD pole figures. At growth rates ?9 /min, CeO2(111) film with single in-plane domain was identified. The formation of CeO2(100) 3-D islands at growth rates of 1-7 /min is a kinetically driven process unlike at growth rates ?9 /min which result in an energetically and thermodynamically more stable CeO2(111) surface.

Nandasiri, Manjula I.; Nachimuthu, Ponnusamy; Varga, Tamas; Shutthanandan, V.; Jiang, Weilin; Kuchibhatla, Satyanarayana V N T; Thevuthasan, Suntharampillai; Seal, Sudipta; Kayani, Asghar N.

2011-01-14T23:59:59.000Z

176

Understanding controls on interfacial wetting at epitaxial graphene: Experiment and Theory  

SciTech Connect

The interaction of water with graphitic carbon at the atomic scale is studied as a function of the hydrophobicity of epitaxial graphene. High resolution X-ray reflectivity combined with both classical and ab initio molecular dynamics simulations allows us to understand how the graphene-water interface changes as the hydrophobicity of intrinsic multilayer graphene (contact angle c = 93 ) is reduced by the presence of substrate and surface defect sites, leading to increased hydrophilicity ( c = 73 ) for zero-layer graphene (i.e., the epitaxial buffer layer). The relationship between water depletion and hydrophobicity (i.e., the hydrophobic gap) is also clarified by the current findings.

Zhou, Hua [Argonne National Laboratory (ANL); Ganesh, Panchapakesan [ORNL; Presser, Volker [Drexel University; Wander, Matthew C [ORNL; Fenter, Paul [Argonne National Laboratory (ANL); Kent, Paul R [ORNL; Jiang, Deen [ORNL; Chialvo, Ariel A [ORNL; Mcdonough, John [Drexel University; Shuford, Kevin L [ORNL; Gogotsi, Yury G. [Drexel University

2012-01-01T23:59:59.000Z

177

Beam History  

NLE Websites -- All DOE Office Websites (Extended Search)

Beam Status Beam History Print Beamline History Request Form To request a beam current histograph from the ALS storage ring beam histograph database, select the year, month, and...

178

Ion beam processing of advanced electronic materials  

SciTech Connect

This report contains research programs discussed at the materials research society symposia on ion beam processing of advanced electronic materials. Major topics include: shallow implantation and solid-phase epitaxy; damage effects; focused ion beams; MeV implantation; high-dose implantation; implantation in III-V materials and multilayers; and implantation in electronic materials. Individual projects are processed separately for the data bases. (CBS)

Cheung, N.W.; Marwick, A.D.; Roberto, J.B. (eds.) (California Univ., Berkeley, CA (USA); International Business Machines Corp., Yorktown Heights, NY (USA). Thomas J. Watson Research Center; Oak Ridge National Lab., TN (USA))

1989-01-01T23:59:59.000Z

179

LaAlO{sub 3}/Si capacitors: Comparison of different molecular beam deposition conditions and their impact on electrical properties  

Science Conference Proceedings (OSTI)

A study of the structural and electrical properties of amorphous LaAlO{sub 3} (LAO)/Si thin films fabricated by molecular beam deposition (MBD) is presented. Two substrate preparation procedures have been explored namely a high temperature substrate preparation technique-leading to a step and terraces surface morphology-and a chemical HF-based surface cleaning. The LAO deposition conditions were improved by introducing atomic plasma-prepared oxygen instead of classical molecular O{sub 2} in the chamber. An Au/Ni stack was used as the top electrode for its electrical characteristics. The physico-chemical properties (surface topography, thickness homogeneity, LAO/Si interface quality) and electrical performance (capacitance and current versus voltage and TunA current topography) of the samples were systematically evaluated. Deposition conditions (substrate temperature of 550 Degree-Sign C, oxygen partial pressure settled at 10{sup -6} Torr, and 550 W of power applied to the O{sub 2} plasma) and post-depositions treatments were investigated to optimize the dielectric constant ({kappa}) and leakage currents density (J{sub Gate} at Double-Vertical-Line V{sub Gate} Double-Vertical-Line = Double-Vertical-Line V{sub FB}- 1 Double-Vertical-Line ). In the best reproducible conditions, we obtained a LAO/Si layer with a dielectric constant of 16, an equivalent oxide thickness of 8.7 A, and J{sub Gate} Almost-Equal-To 10{sup -2}A/cm{sup 2}. This confirms the importance of LaAlO{sub 3} as an alternative high-{kappa} for ITRS sub-22 nm technology node.

Pelloquin, Sylvain; Baboux, Nicolas; Albertini, David; Hourani, Waeel; Plossu, Carole [Lyon Institute of Nanotechnologies (INL), INSA de Lyon, UMR CNRS 5270, 7 avenue Jean Capelle, Villeurbanne F-69621 (France); Saint-Girons, Guillaume; Penuelas, Jose; Grenet, Genevieve; Hollinger, Guy [Lyon Institute of Nanotechnologies (INL), Ecole Centrale de Lyon, UMR CNRS 5270, 36 avenue Guy de Collongue, Ecully F-69134 (France)

2013-01-21T23:59:59.000Z

180

Electric-dipole moment of CaF by molecular-beam, laser-rf, double-resonance study of Stark splittings  

SciTech Connect

The electronic structure of diatomic molecules is much more complex for open-shell sytems (radicals) than for the normal closed-shell systems, and the development of an adequate theoretical understanding will require a substantial upgrading of experimental knowledge in both quality and quantity. The alkaline-earth monohalide family of radicals, with only a single electron outside closed-shell cores, would appear to be a logical starting point for such studies, and there has been a great increase in work in this area in the last few years in spite of the special difficulties of working with free radicals. As the work of measuring the vibrational and rotational structure of the electronic states has become more complete, attention has turned to study of the much weaker spin-rotation and hyperfine interactions. Within the last three years, these interactions have been studied systematically at high precision in the calcium monohalide family with the molecular-beam, laser-rf double-resonance technique. The same method has now been modified and extended to make possible measurement of the electric-dipole moments of these molecules through observation of the Stark splittings of radiofrequency transitions. It is hoped that when considered together, the several types of data will make it possible to understand the ground-state electronic wave functions of these molecules at least qualitatively. 2 figures.

Childs, W.J.; Goodman, L.S.; Nielsen, U.; Pfeufer, V.

1984-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

See the Foundry's full equipment list See the Foundry's full equipment list Nanofabrication Capabilities & Tools Major Capabilities: Instruments and Labs Zeiss Crossbeam 1540 EsB The Molecular Foundry Zeiss Cross-beam is one of the most versatile lithographic and inspection tools allowing fabrication of complex prototypes for nanoelectronics, nano-optical antenna, modifying scanning probe tips, rapid electrical contacting and many other applications. The 1500XB Cross Beam combines the Gemini field emission column (FESEM) with the Orsay Physics focused ion beam (FIB). In addition, the instrument offers a multi-channel gas injection system to allow ion and electron beam induced deposition (IBID and EBID) and chemically assisted ion beam etching (CAIBE). The tool can be used for lithographic patterning of materials or

182

GaSb molecular beam epitaxial growth on p-InP(001) and passivation with in situ deposited Al{sub 2}O{sub 3} gate oxide  

SciTech Connect

The integration of high carrier mobility materials into future CMOS generations is presently being studied in order to increase drive current capability and to decrease power consumption in future generation CMOS devices. If III-V materials are the candidates of choice for n-type channel devices, antimonide-based semiconductors present high hole mobility and could be used for p-type channel devices. In this work we first demonstrate the heteroepitaxy of fully relaxed GaSb epilayers on InP(001) substrates. In a second part, the properties of the Al{sub 2}O{sub 3}/GaSb interface have been studied by in situ deposition of an Al{sub 2}O{sub 3} high-{kappa} gate dielectric. The interface is abrupt without any substantial interfacial layer, and is characterized by high conduction and valence band offsets. Finally, MOS capacitors show well-behaved C-V with relatively low D{sub it} along the bandgap, these results point out an efficient electrical passivation of the Al{sub 2}O{sub 3}/GaSb interface.

Merckling, C.; Brammertz, G.; Hoffmann, T. Y.; Caymax, M.; Dekoster, J. [Interuniversity Microelectronics Center (IMEC vzw), Kapeldreef 75, 3001, Leuven (Belgium); Sun, X. [Katholieke Universiteit Leuven, Celestijnelaan 200D, 3001, Leuven (Belgium); Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520-8284 (United States); Alian, A.; Heyns, M. [Interuniversity Microelectronics Center (IMEC vzw), Kapeldreef 75, 3001, Leuven (Belgium); Katholieke Universiteit Leuven, Celestijnelaan 200D, 3001, Leuven (Belgium); Afanas'ev, V. V. [Katholieke Universiteit Leuven, Celestijnelaan 200D, 3001, Leuven (Belgium)

2011-04-01T23:59:59.000Z

183

Structure of epitaxial (Fe,N) codoped rutile TiO2 thin films by x-ray absorption  

Science Conference Proceedings (OSTI)

Homoepitaxial thin films of Fe:TiO2 and (Fe,N):TiO2 were deposited on rutile(110) by molecular beam epitaxy. X-ray absorption near edge spectroscopy (XANES) spectra were collected at the Ti L-edge, Fe L-edge, O K-edge, N K-edge, and Ti K-edge. No evidence of structural disorder associated with a high concentration of oxygen vacancies is observed. Substitution of Fe for Ti could not be confirmed, although secondary phase Fe2O3 and metallic Fe can be ruled out. The similarity of the N K-edge spectra to O, and the presence of a strong x-ray linear dichroism (XLD) signal for the N K-edge, indicates that N is substitutional for O in the rutile lattice, and is not present as a secondary phase such as TiN. Simulations of the XANES spectra qualitatively confirm substitution, although N appears to be present in more than one local environment. Neither Fe:TiO2 nor (Fe,N):TiO2 exhibit intrinsic room temperature ferromagnetism, despite the presence of mixed valence Fe(II)/Fe(III) in the reduced (Fe,N):TiO2 film.

Kaspar, Tiffany C.; Ney, A.; Mangham, Andrew N.; Heald, Steve M.; Joly, Yves; Ney, V.; Wilhelm, F.; Rogalev, A.; Yakou, Flora; Chambers, Scott A.

2012-07-23T23:59:59.000Z

184

Molecular fountain.  

SciTech Connect

A molecular fountain directs slowly moving molecules against gravity to further slow them to translational energies that they can be trapped and studied. If the molecules are initially slow enough they will return some time later to the position from which they were launched. Because this round trip time can be on the order of a second a single molecule can be observed for times sufficient to perform Hz level spectroscopy. The goal of this LDRD proposal was to construct a novel Molecular Fountain apparatus capable of producing dilute samples of molecules at near zero temperatures in well-defined user-selectable, quantum states. The slowly moving molecules used in this research are produced by the previously developed Kinematic Cooling technique, which uses a crossed atomic and molecular beam apparatus to generate single rotational level molecular samples moving slowly in the laboratory reference frame. The Kinematic Cooling technique produces cold molecules from a supersonic molecular beam via single collisions with a supersonic atomic beam. A single collision of an atom with a molecule occurring at the correct energy and relative velocity can cause a small fraction of the molecules to move very slowly vertically against gravity in the laboratory. These slowly moving molecules are captured by an electrostatic hexapole guiding field that both orients and focuses the molecules. The molecules are focused into the ionization region of a time-of-flight mass spectrometer and are ionized by laser radiation. The new molecular fountain apparatus was built utilizing a new design for molecular beam apparatus that has allowed us to miniaturize the apparatus. This new design minimizes the volumes and surface area of the machine allowing smaller pumps to maintain the necessary background pressures needed for these experiments.

Strecker, Kevin E.; Chandler, David W.

2009-09-01T23:59:59.000Z

185

Beam History  

NLE Websites -- All DOE Office Websites (Extended Search)

Beam History Print Beamline History Request Form To request a beam current histograph from the ALS storage ring beam histograph database, select the year, month, and day, then...

186

Thermoelectric properties of epitaxial TbAs:InGaAs nanocomposites  

SciTech Connect

InGaAs lattice-matched to InP was grown by molecular beam epitaxy with randomly distributed TbAs nanoparticles for thermoelectric power generation applications. TbAs:InGaAs is expected to have a large thermoelectric figure of merit, ZT, particularly at high temperatures, owing to energy band alignment between the nanoparticles and their surrounding matrix. Here, the room temperature thermoelectric properties were measured as a function of TbAs concentration, revealing a maximum thermoelectric power factor of 2.38 W/mK{sup 2} and ZT of 0.19 with 0.2% TbAs. Trends in the thermoelectric properties closely resemble those found in comparable ErAs:InGaAs nanocomposite materials. However, nanoparticles were not observed by scanning transmission electron microscopy in the highest ZT TbAs:InGaAs sample, unlike the highest ZT ErAs:InGaAs sample (0.2% ErAs) and two higher concentration TbAs:InGaAs samples examined. Consistent with expectations concerning the positioning of the Fermi level in these materials, ZT was enhanced by TbAs incorporation largely due to a high Seebeck coefficient, whereas ErAs provided InGaAs with higher conductivity but a lower Seebeck coefficient than that of TbAs:InGaAs. Thermal conductivity was reduced significantly from that of intrinsic thin-film InGaAs only with TbAs concentrations greater than {approx}1.7%.

Clinger, Laura E.; Zide, Joshua M. O. [Materials Science and Engineering Department, University of Delaware, Newark, Delaware 19716 (United States); Pernot, Gilles; Shakouri, Ali [Electrical Engineering Department, University of California, Santa Cruz, California 95064 (United States); Buehl, Trevor E.; Burke, Peter G.; Gossard, Arthur C. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Palmstroem, Christopher J. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106 (United States)

2012-05-01T23:59:59.000Z

187

Substrate-Induced Band-Gap Opening in Epitaxial Graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

Substrate-Induced Band-Gap Opening in Epitaxial Graphene Substrate-Induced Band-Gap Opening in Epitaxial Graphene Print Wednesday, 26 March 2008 00:00 Prospective challengers to...

188

Quantification of Dopant Concentrations in Diluted Magnetic Semiconductors using Ion Beam Techniques  

SciTech Connect

It has recently been demonstrated that magnetically doped TiO2 and SnO2 show ferromagnetism at room-temperature and Curie temperatures above room temperature. However, accurate knowledge of dopant concentrations is necessary to quantify magnetic moments in these materials. Rutherford Backscattering spectrometry (RBS) is one of the powerful techniques to quantify magnetic transition metal dopant concentrations in these materials. However, in some cases, the interference of RBS signals for different dopants and substrate elements in these materials makes analysis difficult. In this work, we demonstrate that particle induced x-ray emission (PIXE) can be successfully used to quantify the magnetic transition element dopants in several room temperature ferromagnetic materials synthesized using three different synthesis methods: oxygen plasma assisted molecular beam epitaxy, ion implantation and wet chemical methods.

Shutthanandan, V.; Thevuthasan, Suntharampillai; Droubay, Timothy; Kaspar, Tiffany C.; Punnoose, Alex; Hays, Jason; Chambers, Scott A.

2006-08-01T23:59:59.000Z

189

PHOTOELECTRON PHOTOION MOLECULAR BEAM SPECTROSCOPY  

E-Print Network (OSTI)

Phase Experimental Station at SSRL A. B. C. D. Introductionmass spectrometer used at SSRL. The photon baam ia comingon the 8 (1-2) line at SSRL after passing through a 1500 A

Trevor, Dennis J.

2010-01-01T23:59:59.000Z

190

Growth of homo-epitaxial silicon at low temperatures using hot wire chemical vapor deposition  

DOE Green Energy (OSTI)

The authors report on the first known growth of high-quality epitaxial Si via the hot wire chemical vapor deposition (HWCVD) method. This method yields device-quality epitaxial Si at the comparatively low temperatures of 195 to 450 C, and relatively high growth rates of 3 to 20 {angstrom}/sec. Layers up to 4,500-{angstrom} thick have been grown. These epitaxial layers have been characterized by transmission electron microscopy (TEM), indicating large regions of nearly perfect atomic registration. Electron channeling patterns (ECPs) generated on a scanning electron microscope (SEM) have been used to characterize as well as optimize the growth process. Electron beam induced current (EBIC) characterization has also been performed, indicating defect densities as low as 5 x 104/cm{sup 2}. Secondary ion beam mass spectrometry (SIMS) data shows that these layers have reasonable impurity levels within the constraints of the current deposition system. Both n and p-type layers were grown, and p/n diodes have been fabricated.

Thiesen, J.; Jones, K.M.; Matson, R.; Reedy, R.; Crandall, R.; Iwaniczko, E.; Mahan, H.

1999-12-13T23:59:59.000Z

191

Catalytic Steam Reforming of Gasifier Tars: On-Line Monitoring of Tars with a Transportable Molecular-Beam Mass Spectrometer; Milestone Completion Report  

DOE Green Energy (OSTI)

A method for evaluating catalytic tar decomposition in real time is presented. The effectiveness of two catalysts are compared. A key technical and economic barrier to commercialization of biomass gasification technologies is the removal of tars that are unavoidably formed in this thermochemical process. Tars contain fuel value; however, they are problematic in gas engines (both reciprocating and turbine) because they condense in the fuel delivery system, forming deposits that negatively affect operation and efficiency. These tars also combust with high luminosity, potentially forming soot particles. The conventional technology for tar removal is wet scrubbing. Although this approach has shown some success, there are significant equipment and operating costs associated with it. In order to prevent the generation of toxic wastewater, the tars must be separated and either disposed as hazardous waste or, preferably, combusted in the gasification plant. A conceptually better approach is catalytic steam reforming of the tars to hydrogen and carbon monoxide (CO), effectively increasing the gasification efficiency and eliminating the problems mentioned above. In FY2000, Battelle Columbus Laboratories attempted to demonstrate integrated gasification-gas turbine operation using catalytic steam reforming of tars. NREL participated in those tests using the transportable molecular-beam mass spectrometer (TMBMS) to monitor the catalytic reactor's performance on-line [10]. Unfortunately, the pilot plant tests encountered operational problems that prevented conclusive determination of the efficacy of the selected catalyst (Battelle's DN34). In FY2001, NREL performed on-site tar steam reforming tests using a slip-stream of hot pyrolysis gas from the Thermochemical Process Development Unit (TCPDU), which was directed to a bench-scale fluidized bed reactor system designed expressly for this purpose. Supporting this effort, the TMBMS was employed to provide on-line analysis of the tar conversion. The gas composition changes were monitored by two identical gas chromatographs (GCs), and modified method 5 sampling was performed to obtain gravimetric conversion data. The combination of these analytical techniques provided definitive catalyst performance data, as well as linkage to previous and on-going work elsewhere. Two catalysts were tested: nickel (Ni) on potassium promoted alumina (Sued-Chemie C11-NK), used commercially for naphtha steam reforming, and alumina (Battelle's DN34) claimed to be effective for gasifier tar decomposition. In addition, sand was tested as an inert reference material.

Carpenter, D.; Ratcliff, M.; Dayton, D.

2002-05-01T23:59:59.000Z

192

Electrostatic transfer of epitaxial graphene to glass.  

SciTech Connect

We report on a scalable electrostatic process to transfer epitaxial graphene to arbitrary glass substrates, including Pyrex and Zerodur. This transfer process could enable wafer-level integration of graphene with structured and electronically-active substrates such as MEMS and CMOS. We will describe the electrostatic transfer method and will compare the properties of the transferred graphene with nominally-equivalent 'as-grown' epitaxial graphene on SiC. The electronic properties of the graphene will be measured using magnetoresistive, four-probe, and graphene field effect transistor geometries [1]. To begin, high-quality epitaxial graphene (mobility 14,000 cm2/Vs and domains >100 {micro}m2) is grown on SiC in an argon-mediated environment [2,3]. The electrostatic transfer then takes place through the application of a large electric field between the donor graphene sample (anode) and the heated acceptor glass substrate (cathode). Using this electrostatic technique, both patterned few-layer graphene from SiC(000-1) and chip-scale monolayer graphene from SiC(0001) are transferred to Pyrex and Zerodur substrates. Subsequent examination of the transferred graphene by Raman spectroscopy confirms that the graphene can be transferred without inducing defects. Furthermore, the strain inherent in epitaxial graphene on SiC(0001) is found to be partially relaxed after the transfer to the glass substrates.

Ohta, Taisuke; Pan, Wei; Howell, Stephen Wayne; Biedermann, Laura Butler; Beechem Iii, Thomas Edwin; Ross, Anthony Joseph, III

2010-12-01T23:59:59.000Z

193

Hyperfine structure of the X /sup 2/. sigma. /sup +/ ground state of Ca /sup 35/Cl and Ca /sup 37/Cl by molecular-beam, laser-rf double resonance  

Science Conference Proceedings (OSTI)

The hyperfine structure of the X /sup 2/..sigma../sup +/ state of Ca /sup 35/Cl and Ca /sup 37/Cl, unresolved in previous studies, has been investigated in detail by the molecular-beam, laser-rf, double-resonance technique. Results for the spin-rotation interaction and the dipole and quadrupole hfs constants are given in the form of Dunham coefficients so that the N'' and v'' dependence of each constant can be explicitly exhibited. The results, after dividing out the purely nuclear effects, fall between the corresponding values for CaF and CaBr, as expected.

Childs, W.J.; Cok, D.R.; Goodman, L.S.

1982-04-15T23:59:59.000Z

194

Beam Purification by Photodetachment  

Science Conference Proceedings (OSTI)

Ion beam purity is of crucial importance to many basic and applied studies. Selective photodetachment has been proposed to suppress unwanted species in negative ion beams while preserving the intensity of the species of interest. A highly efficient technique based on photodetachment in a gas-filled radio frequency quadrupole ion cooler has been demonstrated. In off-line experiments with stable ions, up to 104 times suppression of the isobar contaminants in a number of interesting radioactive negative ion beams has been demonstrated. For selected species, this technique promises experimental possibilities in studies on exotic nuclei, accelerator mass spectrometry, and fundamental properties of negative atomic and molecular ions.

Liu, Yuan [ORNL; Beene, James R [ORNL; Havener, Charles C [ORNL; Galindo-Uribarri, Alfredo {nmn} [ORNL; Andersson, P. [University of Gothenburg, Sweden; Lindahl, A. O. [University of Gothenburg, Sweden; Hanstorp, D. [University of Gothenburg, Sweden; Forstner, Dr. Oliver [University of Vienna, Austria; Gottwald, T. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Wendt, K. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany

2012-01-01T23:59:59.000Z

195

Self-assembly of InAs ring complexes on InP substrates by droplet epitaxy  

Science Conference Proceedings (OSTI)

We report the self-assembly of InAs ring complexes on InP (100) substrates by droplet epitaxy. Single-ring, ring-disk complex, and concentric double-ring structures were formed by controlling the As beam flux and substrate temperature. A clear photoluminescence signal was detected in a sample where InAs rings were embedded in InGaAs.

Noda, T.; Mano, T.; Jo, M.; Kawazu, T. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Sakaki, H. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Toyota Technological Institute, 2-12-1 Hisakata, Tempaku-ku, Nagoya 468-8511 (Japan)

2012-09-15T23:59:59.000Z

196

Epitaxial strontium titanate films grown by atomic layer deposition on SrTiO{sub 3}-buffered Si(001) substrates  

SciTech Connect

Epitaxial strontium titanate (STO) films have been grown by atomic layer deposition (ALD) on Si(001) substrates with a thin STO buffer layer grown by molecular beam epitaxy (MBE). Four unit cells of STO grown by MBE serve as the surface template for ALD growth. The STO films grown by ALD are crystalline as-deposited with minimal, if any, amorphous SiO{sub x} layer at the STO-Si interface. The growth of STO was achieved using bis(triisopropylcyclopentadienyl)-strontium, titanium tetraisopropoxide, and water as the coreactants at a substrate temperature of 250 Degree-Sign C. In situ x-ray photoelectron spectroscopy (XPS) analysis revealed that the ALD process did not induce additional Si-O bonding at the STO-Si interface. Postdeposition XPS analysis also revealed sporadic carbon incorporation in the as-deposited films. However, annealing at a temperature of 250 Degree-Sign C for 30 min in moderate to high vacuum (10{sup -6}-10{sup -9} Torr) removed the carbon species. Higher annealing temperatures (>275 Degree-Sign C) gave rise to a small increase in Si-O bonding, as indicated by XPS, but no reduced Ti species were observed. X-ray diffraction revealed that the as-deposited STO films were c-axis oriented and fully crystalline. A rocking curve around the STO(002) reflection gave a full width at half maximum of 0.30 Degree-Sign {+-} 0.06 Degree-Sign for film thicknesses ranging from 5 to 25 nm. Cross-sectional transmission electron microscopy revealed that the STO films were continuous with conformal growth to the substrate and smooth interfaces between the ALD- and MBE-grown STO. Overall, the results indicate that thick, crystalline STO can be grown on Si(001) substrates by ALD with minimal formation of an amorphous SiO{sub x} layer using a four-unit-cell STO buffer layer grown by MBE to serve as the surface template.

McDaniel, Martin D.; Posadas, Agham; Ngo, Thong Q.; Dhamdhere, Ajit; Smith, David J.; Demkov, Alexander A.; Ekerdt, John G. [Department of Chemical Engineering, University of Texas at Austin, 1 University Station C0400, Austin, Texas 78712 (United States); Department of Physics, University of Texas at Austin, 1 University Station C1600, Austin, Texas 78712 (United States); Department of Chemical Engineering, University of Texas at Austin, 1 University Station C0400, Austin, Texas 78712 (United States); Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Department of Physics, University of Texas at Austin, 1 University Station C1600, Austin, Texas 78712 (United States); Department of Chemical Engineering, University of Texas at Austin, 1 University Station C0400, Austin, Texas 78712 (United States)

2013-01-15T23:59:59.000Z

197

Junction Transport in Epitaxial Film Silicon Heterojunction Solar Cells: Preprint  

Science Conference Proceedings (OSTI)

We report our progress toward low-temperature HWCVD epitaxial film silicon solar cells on inexpensive seed layers, with a focus on the junction transport physics exhibited by our devices. Heterojunctions of i/p hydrogenated amorphous Si (a-Si) on our n-type epitaxial crystal Si on n++ Si wafers show space-charge-region recombination, tunneling or diffusive transport depending on both epitaxial Si quality and the applied forward voltage.

Young, D. L.; Li, J. V.; Teplin, C. W.; Stradins, P.; Branz, H. M.

2011-07-01T23:59:59.000Z

198

Selective epitaxy using the GILD process  

DOE Patents (OSTI)

The present invention comprises a method of selective epitaxy on a semiconductor substrate. The present invention provides a method of selectively forming high quality, thin GeSi layers in a silicon circuit, and a method for fabricating smaller semiconductor chips with a greater yield (more error free chips) at a lower cost. The method comprises forming an upper layer over a substrate, and depositing a reflectivity mask which is then removed over selected sections. Using a laser to melt the unmasked sections of the upper layer, the semiconductor material in the upper layer is heated and diffused into the substrate semiconductor material. By varying the amount of laser radiation, the epitaxial layer is formed to a controlled depth which may be very thin. When cooled, a single crystal epitaxial layer is formed over the patterned substrate. The present invention provides the ability to selectively grow layers of mixed semiconductors over patterned substrates such as a layer of Ge{sub x}Si{sub 1-x} grown over silicon. Such a process may be used to manufacture small transistors that have a narrow base, heavy doping, and high gain. The narrowness allows a faster transistor, and the heavy doping reduces the resistance of the narrow layer. The process does not require high temperature annealing; therefore materials such as aluminum can be used. Furthermore, the process may be used to fabricate diodes that have a high reverse breakdown voltage and a low reverse leakage current.

Weiner, K.H.

1990-12-31T23:59:59.000Z

199

Rapid, controllable growth of epitaxial silicon films - Energy ...  

Many of the current industry cells in ... A method of producing epitaxial silicon films on a c-Si wafer substrate using hot wire chemical vapor ...

200

Substrate-Induced Band-Gap Opening in Epitaxial Graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

Substrate-Induced Band-Gap Opening in Epitaxial Graphene Print Prospective challengers to silicon, the long-reigning king of semiconductors for computer chips and other electronic...

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201

Epitaxial silicon growth for solar cells. Final report  

DOE Green Energy (OSTI)

The objectives of this contract were: (1) to determine the feasibility of silicon epitaxial growth on low-cost silicon substrates for the development of silicon sheet capable of producing low-cost, high efficiency solar cells; (2) to achieve a goal of 12% (AM-0) efficient solar cells fabricated on thin epitaxial layers (<25 ..mu..m) grown on low-cost substrates; and (3) to evaluate the add-on cost for the epitaxial process and to develop low-cost epitaxial growth procedures for application in conjunction with low-cost silicon substrates. The basic epitaxial procedures and solar-cell fabrication and evaluation techniques are described, followed by a discussion of the development of baseline epitaxial solar-cell structures, grown on high-quality conventional silicon substrates. This work resulted in the definition of three basic structures which reproducibly yielded efficiencies in the range of 12 to 13.7%. These epitaxial growth procedures and baseline structures were then used to grow diagnostic layers and solar cells on four potentially low-cost silicon substrates. A description of the crystallographic properties of such layers and the performance of epitaxially grown solar cells fabricated on these materials is given. The major results were the achievement of cell efficiencies of 10.6 to 11.2% on multigrained substrates and approx. 13% on a low-cost single-crystal substrate. An advanced epitaxial reactor, the Rotary Disc, is described. The results of growing solar-cell structures of the baseline type and on low-cost substrates are given. The add-on cost for the epitaxial process is assessed. These cost estimates show a value of approx. 0.46/W using existing or near-term technologies and project an add-on cost of $0.10/W for future reactors.

D'Aiello, R.V.; Robinson, P.H.; Richman, D.

1979-04-01T23:59:59.000Z

202

Epitaxial oxygen sponges as low temperature catalysts | ornl.gov  

NLE Websites -- All DOE Office Websites (Extended Search)

Functional Materials for Energy Functional Materials for Energy Epitaxial oxygen sponges as low temperature catalysts September 10, 2013 Crystal structure of SrCoO2.5 superimposed on a scanning transmission electron microscopy image of an epitaxially stabilized oxygen sponge. Fast and reversible redox reactions at considerably reduced temperatures are achieved by epitaxial stabilization of multivalent transition metal oxides. This illustrates the unprecedented potential of complex oxides for oxide-ionics, where oxidation state changes are used for energy generation, storage and electrochemical sensing. Thermomechanical degradation reduces the overall performance and lifetime of many perovskite oxides undergoing reversible redox reactions, such as those found in solid oxide fuel cells, rechargeable batteries,

203

Effects of Epitaxial Graphene Stacking, Strain, and Thickness ...  

Science Conference Proceedings (OSTI)

Register as a New User ... Additionally, we have examined epitaxial graphene with mobility values of 25 18,100 cm2/Vs, and show that Raman topography is a...

204

Epitaxial CoSi2 on MOS devices  

DOE Patents (OSTI)

An Si.sub.x N.sub.y or SiO.sub.x N.sub.y liner is formed on a MOS device. Cobalt is then deposited and reacts to form an epitaxial CoSi.sub.2 layer underneath the liner. The CoSi.sub.2 layer may be formed through a solid phase epitaxy or reactive deposition epitaxy salicide process. In addition to high quality epitaxial CoSi.sub.2 layers, the liner formed during the invention can protect device portions during etching processes used to form device contacts. The liner can act as an etch stop layer to prevent excessive removal of the shallow trench isolation, and protect against excessive loss of the CoSi.sub.2 layer.

Lim, Chong Wee (Urbana, IL); Shin, Chan Soo (Daejeon, KR); Petrov, Ivan Georgiev (Champaign, IL); Greene, Joseph E. (Champaign, IL)

2005-01-25T23:59:59.000Z

205

Biaxially-Textured Photovoltaic Film Crystal Silicon on Ion Beam Assisted Deposition CaF2 Seed Layers on Glass  

SciTech Connect

We grow biaxially textured heteroepitaxial crystal silicon (c-Si) films on display glass as a low-cost photovoltaic material. We first fabricate textured CaF{sub 2} seed layers using ion-beam assisted deposition, then coat the CaF{sub 2} with a thin, evaporated epitaxial Ge buffer and finally deposit heteroepitaxial silicon on the Ge. The silicon is grown by hot-wire chemical vapor deposition, a high-rate, scalable epitaxy technology. Electron and X-ray diffraction confirm the biaxial texture of the CaF{sub 2} and epitaxial growth of the subsequent layers. Transmission electron microscopy reveals columnar silicon grains about 500 nm across. We fabricate a proof-of-concept epitaxial film c-Si solar cell with an open circuit voltage of 375 mV that is limited by minority carrier lifetime.

Groves, J. R.; Li, J. B.; Clemens, B. M.; LaSalvia, V.; Hasoon, F.; Branz, H. M.; Teplin, C. W.

2012-05-01T23:59:59.000Z

206

Surface-Induced Orientation Control of CuPc Molecules for the Epitaxial Growth of Highly Ordered Organic Crystals on Graphene  

Science Conference Proceedings (OSTI)

The epitaxial growth and preferred molecular orientation of copper phthalocyanine (CuPc) molecules on graphene has been systematically investigated and compared with growth on Si substrates, demonstrating the role of surface-mediated interactions in determining molecular orientation. X-ray scattering and diffraction, scanning tunneling microscopy, scanning electron microscopy, and first-principles theoretical calculations were used to show that the nucleation, orientation and packing of CuPc molecules on films of graphene are fundamentally different compared to those grown on Si substrates. Interfacial dipole interactions induced by charge transfer between CuPc molecules and graphene are shown to epitaxially align the CuPc mole-cules in a face-on orientation in a series of ordered superstructures. At high temperatures, CuPc molecules lie flat with respect to the graphene substrate to form strip-like CuPc crystals with micron sizes containing monocrystalline grains. Such large epitaxial crystals may potentially enable bulk-like properties to improve the device properties in organic electronics, which charge transport, exciton diffusion and dissociation are currently limited by grain size effects and molecular orientation.

Xiao, Kai [ORNL; Deng, Wan [ORNL; Keum, Jong Kahk [ORNL; Yoon, Mina [ORNL; Vlassiouk, Ivan V [ORNL; Clark, Kendal W [ORNL; Li, An-Ping [ORNL; Kravchenko, Ivan I [ORNL; Gu, Gong [University of Tennessee, Knoxville (UTK); Payzant, E Andrew [ORNL; Sumpter, Bobby [ORNL; Smith, Sean C [ORNL; Browning, Jim [ORNL; Geohegan, David B [ORNL

2013-01-01T23:59:59.000Z

207

MATERIAL QUALITY CHARACTERIZATION OF CDZNTE SUBSTRATES FOR HGCDTE EPITAXY.  

Science Conference Proceedings (OSTI)

CdZnTe (CZT) has been traditionally used as substrate for HgCdTe (MCT) epitaxy. The constraint of good lattice matching plays a fundamental role in the use of this substrate. In, fact, despite the difficulties in growing large area of affordable high-quality substrates, CZT wafers remain the best choice for high yield infrared devices. Nevertheless, material quality of the substrate and epilayer play a limiting role in IR focal plane array (FPA) detector technology. Furthermore, data suggest that the quality of the epilayer is affected by imperfections in the CZT substrate. In addition the pixel size for the current generation of FPAs (less than 20 {micro}m) suggests a need for detailed microscale characterization and an understanding of the substrates and epilayers on at least the spatial scale of the pixel dimensions. In an effort to understand the correlation between material quality and device performances, we have begun to study CZT substrates to investigate bulk and surface properties. The National Synchrotron Light Source (NSLS, BNL) permits a wide variety of material investigations that take advantage of the highly collimated photon radiation emitted from the X-ray and VUV-IR rings. Synchrotron radiation offers the capability to combine good resolution and shorter exposure times than conventional X-ray sources, which allow the ability for high-resolution mapping of relatively large areas in an acceptable amount of time. Transmission X-ray diffraction techniques, such as white beam topography and rocking curves, have already been used for bulk investigation [l] as well as IR transmission microspectroscopy. Surface studies on CZT substrates were performed using X-ray diffraction. By correlating results from the different material and device investigations, we offer a more complete characterization of bulk and surface crystalline quality and their effects on device performance. Information on the location of grain boundaries and precipitates, evaluation of impurity content, and stoichiometry variations will be reported. The ultimate goal is to understand the defects in CZT substrates and their effects on the performance and uniformity of MCT epilayers [2], and then to apply this understanding to produce better infrared detectors.

CARINI, G.A.; BOLOTNIKOV, A.E.; CAMARDA, G.S.; JAMES, R.B.; ET AL.

2005-08-18T23:59:59.000Z

208

Substrate-Induced Band-Gap Opening in Epitaxial Graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

Substrate-Induced Band-Gap Opening in Epitaxial Graphene Print Substrate-Induced Band-Gap Opening in Epitaxial Graphene Print Prospective challengers to silicon, the long-reigning king of semiconductors for computer chips and other electronic devices, have to overcome silicon's superb collection of materials properties as well as sophisticated fabrication technologies refined by six decades of effort by materials scientists and engineers. Graphene, one of the latest contenders, has a rather impressive list of features of its own but has lacked a key characteristic of all semiconductors, an energy gap (band gap) in its electronic band structure. A multi-institutional collaboration under the leadership of researchers with Berkeley Lab and the University of California, Berkeley, have now demonstrated that growing an epitaxial film of graphene on a silicon carbide substrate results in a significant band gap, 0.26 electron volts (eV), an important step toward making graphene useful as a semiconductor.

209

Substrate-Induced Band-Gap Opening in Epitaxial Graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

Substrate-Induced Band-Gap Opening in Epitaxial Graphene Print Substrate-Induced Band-Gap Opening in Epitaxial Graphene Print Prospective challengers to silicon, the long-reigning king of semiconductors for computer chips and other electronic devices, have to overcome silicon's superb collection of materials properties as well as sophisticated fabrication technologies refined by six decades of effort by materials scientists and engineers. Graphene, one of the latest contenders, has a rather impressive list of features of its own but has lacked a key characteristic of all semiconductors, an energy gap (band gap) in its electronic band structure. A multi-institutional collaboration under the leadership of researchers with Berkeley Lab and the University of California, Berkeley, have now demonstrated that growing an epitaxial film of graphene on a silicon carbide substrate results in a significant band gap, 0.26 electron volts (eV), an important step toward making graphene useful as a semiconductor.

210

High sensitive quasi freestanding epitaxial graphene gassensor on 6H-SiC  

E-Print Network (OSTI)

We have measured the electrical response to NO$_2$, N$_2$, NH$_3$ and CO for epitaxial graphene and quasi freestanding epitaxial graphene on 6H-SiC substrates. Quasi freestanding epitaxial graphene shows a 6 fold increase in NO2 sensitivity compared to epitaxial graphene. Both samples show a sensitivity better than the experimentally limited 1 ppb. The strong increase in sensitivity of quasi freestanding epitaxial graphene can be explained by a Fermi-energy close to the Dirac Point leading to a strongly surface doping dependent sample resistance. Both sensors show a negligible sensitivity to N$_2$, NH$_3$ and CO.

Iezhokin, I; Brongersma, S H; Giesbers, A J M; Flipse, C F J

2013-01-01T23:59:59.000Z

211

Ge epitaxial refill deposition techniques for fabricating pedestal transistor structures  

Science Conference Proceedings (OSTI)

An etch-epitaxial refill technique is described for the fabrication of integrated high-speed Ge transistor structures having a pedestal configuration. The device areas surrounding 0.1 ohm-cm mesa structures were refilled with Ge having a resistivity ...

V. J. Silvestri; T. B. Light; H. N. Yu; A. Reisman

1972-01-01T23:59:59.000Z

212

BEAM LINE  

NLE Websites -- All DOE Office Websites (Extended Search)

BEAM LINE BEAM LINE 45 W ILHELM ROENTGEN'S INITIAL DISCOVERY of X-radiation in 1895 led immediately to practical applications in medicine. Over the next few decades X rays proved to be an invaluable tool for the investigation of the micro-world of the atom and the development of the quantum theory of matter. Almost a century later, telescopes designed to detect X-radiation are indispensable for understanding the structure and evolution of the macro-world of stars, galaxies, and the Universe as a whole. The X-Ray Universe by WALLACE H. TUCKER X-ray images of the Universe are strikingly different from the usual visible-light images. 46 SUMMER 1995 did not think: I investigated." Undeterred by NASA's rejection of a proposal to search for cosmic X-radiation, Giacconi persuaded the

213

Accelerator beam profile analyzer  

DOE Patents (OSTI)

A beam profile analyzer employing sector or quadrant plates each servo controlled to outline the edge of a beam.

Godel, Julius B. (Bayport, NY); Guillaume, Marcel (Grivegnee, BE); Lambrecht, Richard M. (East Quogue, NY); Withnell, Ronald (East Setauket, NY)

1976-01-01T23:59:59.000Z

214

Methods of preparing flexible photovoltaic devices using epitaxial liftoff, and preserving the integrity of growth substrates used in epitaxial growth  

DOE Patents (OSTI)

There is disclosed methods of making photosensitive devices, such as flexible photovoltaic (PV) devices, through the use of epitaxial liftoff. Also described herein are methods of preparing flexible PV devices comprising a structure having a growth substrate, wherein the selective etching of protective layers yields a smooth growth substrate that us suitable for reuse.

Forrest, Stephen R; Zimmerman, Jeramy; Lee, Kyusang; Shiu, Kuen-Ting

2013-02-19T23:59:59.000Z

215

Cosine (Cobalt Silicide Growth Through Nitrogen-Induced Epitaxy) Process For Epitaxial Cobalt Silicide Formation For High Performance Sha  

DOE Patents (OSTI)

A method for forming an epitaxial cobalt silicide layer on a MOS device includes sputter depositing cobalt in an ambient to form a first layer of cobalt suicide on a gate and source/drain regions of the MOS device. Subsequently, cobalt is sputter deposited again in an ambient of argon to increase the thickness of the cobalt silicide layer to a second thickness.

Lim, Chong Wee (Urbana, IL); Shin, Chan Soo (Daejeon, KR); Gall, Daniel (Troy, NY); Petrov, Ivan Georgiev (Champaign, IL); Greene, Joseph E. (Champaign, IL)

2004-09-28T23:59:59.000Z

216

Steve Blankenship  

Science Conference Proceedings (OSTI)

... is in designing and building surface instrumentation and thin-film and molecular beam epitaxy systems, he also has a broad range of skills that can ...

2010-10-05T23:59:59.000Z

217

Beam purification by photodetachment (invited)  

Science Conference Proceedings (OSTI)

Ion beam purity is of crucial importance to many basic and applied studies in nuclear science. Selective photodetachment has been proposed to suppress unwanted species in negative ion beams while preserving the intensity of the species of interest. A highly efficient technique based on photodetachment in a gas-filled radio frequency quadrupole ion cooler has been demonstrated. In off-line experiments with stable ions, up to 10{sup 4} times suppression of the isobar contaminants in a number of interesting radioactive negative ion beams has been demonstrated. For selected species, this technique promises new experimental possibilities in studies on exotic nuclei, accelerator mass spectrometry, and fundamental properties of negative atomic and molecular ions.

Liu, Y.; Beene, J. R.; Galindo-Uribarri, A.; Havener, C. C. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Andersson, P.; Forstner, O. [Vera Laboratory, Fakultaet fuer Physik, Universitaet Wien, AT-1090 Wien (Austria); Gottwald, T.; Wendt, K. [Institute of Physics, Johannes Gutenberg-University Mainz, D-55099 Mainz (Germany); Hanstorp, D.; Lindahl, A. O. [Department of Physics, University of Gothenburg, SE-412 96 Gothenburg (Sweden)

2012-02-15T23:59:59.000Z

218

Vibrational spectra of nanowires measured using laser doppler vibrometry and STM studies of epitaxial graphene : an LDRD fellowship report.  

Science Conference Proceedings (OSTI)

A few of the many applications for nanowires are high-aspect ratio conductive atomic force microscope (AFM) cantilever tips, force and mass sensors, and high-frequency resonators. Reliable estimates for the elastic modulus of nanowires and the quality factor of their oscillations are of interest to help enable these applications. Furthermore, a real-time, non-destructive technique to measure the vibrational spectra of nanowires will help enable sensor applications based on nanowires and the use of nanowires as AFM cantilevers (rather than as tips for AFM cantilevers). Laser Doppler vibrometry is used to measure the vibration spectra of individual cantilevered nanowires, specifically multiwalled carbon nanotubes (MWNTs) and silver gallium nanoneedles. Since the entire vibration spectrum is measured with high frequency resolution (100 Hz for a 10 MHz frequency scan), the resonant frequencies and quality factors of the nanowires are accurately determined. Using Euler-Bernoulli beam theory, the elastic modulus and spring constant can be calculated from the resonance frequencies of the oscillation spectrum and the dimensions of the nanowires, which are obtained from parallel SEM studies. Because the diameters of the nanowires studied are smaller than the wavelength of the vibrometer's laser, Mie scattering is used to estimate the lower diameter limit for nanowires whose vibration can be measured in this way. The techniques developed in this thesis can be used to measure the vibrational spectra of any suspended nanowire with high frequency resolution Two different nanowires were measured - MWNTs and Ag{sub 2}Ga nanoneedles. Measurements of the thermal vibration spectra of MWNTs under ambient conditions showed that the elastic modulus, E, of plasma-enhanced chemical vapor deposition (PECVD) MWNTs is 37 {+-} 26 GPa, well within the range of E previously reported for CVD-grown MWNTs. Since the Ag{sub 2}Ga nanoneedles have a greater optical scattering efficiency than MWNTs, their vibration spectra was more extensively studied. The thermal vibration spectra of Ag{sub 2}Ga nanoneedles was measured under both ambient and low-vacuum conditions. The operational deflection shapes of the vibrating Ag{sub 2}Ga nanoneedles was also measured, allowing confirmation of the eigenmodes of vibration. The modulus of the crystalline nanoneedles was 84.3 {+-} 1.0 GPa. Gas damping is the dominate mechanism of energy loss for nanowires oscillating under ambient conditions. The measured quality factors, Q, of oscillation are in line with theoretical predictions of air damping in the free molecular gas damping regime. In the free molecular regime, Q{sub gas} is linearly proportional to the density and diameter of the nanowire and inversely proportional to the air pressure. Since the density of the Ag{sub 2}Ga nanoneedles is three times that of the MWNTs, the Ag{sub 2}Ga nanoneedles have greater Q at atmospheric pressures. Our initial measurements of Q for Ag{sub 2}Ga nanoneedles in low-vacuum (10 Torr) suggest that the intrinsic Q of these nanoneedles may be on the order of 1000. The epitaxial carbon that grows after heating (000{bar 1}) silicon carbide (SiC) to high temperatures (1450-1600) in vacuum was also studied. At these high temperatures, the surface Si atoms sublime and the remaining C atoms reconstruct to form graphene. X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM) were used to characterize the quality of the few-layer graphene (FLG) surface. The XPS studies were useful in confirming the graphitic composition and measuring the thickness of the FLG samples. STM studies revealed a wide variety of nanometer-scale features that include sharp carbon-rich ridges, moire superlattices, one-dimensional line defects, and grain boundaries. By imaging these features with atomic scale resolution, considerable insight into the growth mechanisms of FLG on the carbon-face of SiC is obtained.

Biedermann, Laura Butler

2009-09-01T23:59:59.000Z

219

Faceted ceramic fibers, tapes or ribbons and epitaxial devices therefrom  

SciTech Connect

A crystalline article includes a single-crystal ceramic fiber, tape or ribbon. The fiber, tape or ribbon has at least one crystallographic facet along its length, which is generally at least one meter long. In the case of sapphire, the facets are R-plane, M-plane, C-plane or A-plane facets. Epitaxial articles, including superconducting articles, can be formed on the fiber, tape or ribbon.

Goyal, Amit (Knoxville, TN)

2012-07-24T23:59:59.000Z

220

Simple beam profile monitor  

Science Conference Proceedings (OSTI)

An inexpensive beam profile monitor is based on the well proven rotating wire method. The monitor can display beam position and shape in real time for particle beams of most energies and beam currents up to 200{mu}A. Beam shape, position cross-section and other parameters are displayed on a computer screen.

Gelbart, W.; Johnson, R. R.; Abeysekera, B. [ASD Inc. Garden Bay, BC (Canada); Best Theratronics Ltd Ottawa Ontario (Canada); PharmaSpect Ltd., Burnaby BC (Canada)

2012-12-19T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

Final Report: Integrated Multiscale Modeling of Molecular Computing Devices  

Science Conference Proceedings (OSTI)

The general theme of this research has been to expand the capabilities of a simulation technique, Kinetic Monte Carlo (KMC) and apply it to study self-assembled nano-structures on epitaxial thin films. KMC simulates thin film growth and evolution by replacing the detailed dynamics of the system??s evolution, which might otherwise be studied using molecular dynamics, with an appropriate stochastic process.

Tim Schulze, University of Tennessee, Knoxville

2012-11-01T23:59:59.000Z

222

Growth of Thick, On-Axis SiC Epitaxial Layers by High Temperature ...  

Science Conference Proceedings (OSTI)

... Layers by High Temperature Halide CVD for High Voltage Power Devices ... rate, high temperature process ideally suited for thick epitaxial requirements.

223

A5, Photovoltaic-Quality Silicon Epitaxy by Hot-Wire CVD at Glass ...  

Science Conference Proceedings (OSTI)

However, PV applications require that the epitaxy be done at high growth rates and ... Using a simple growth rate model, we have optimized gas utilization and...

224

Dc slice imaging, crossed beam reaction of chlorine radical with butane.  

E-Print Network (OSTI)

?? We present an investigation of the reaction dynamics of Cl radicals with Butane using crossed molecular beams, at two collision energies: ~ 6.5 and (more)

Abdul ghani, Tarek Oussama

2012-01-01T23:59:59.000Z

225

New plasma source of hydrides for epitaxial growth. Final subcontract report, 15 April 1991--3 September 1993  

DOE Green Energy (OSTI)

This report describes a novel plasma-activated selenium source that was developed during the course of this subcontract and which is significantly different than any other heretofore reported in the scientific literature. It involves microwave excited, magnetically confined plasma sources that are intended to operate under electron cyclotron resonance (ECR) conditions at 2.455 GHz. This source is designed to excite and dissociate the molecular vapor evaporating or subliming from a heated solid or liquid reservoir. It can combine an effusion cell vapor flux with a stream of hydrogen or helium gas, enabling the in-situ generation of hydrides for use in low-pressure growth techniques where long mean free paths are desirable. Experiments were conducted to demonstrate a stable discharge within the source, and measures were identified to improve its operational characteristics. Application of this novel source is anticipated to enable a low-temperature, safe process for the growth of high-quality epitaxial compound semiconductor films. This reduction of epitaxial growth temperatures may enable the fabrication of novel photovoltaic devices that have heretofore been impossible due to the deleterious effects of interdiffusion at heterointerfaces resulting from the high temperatures required to grow adequate quality material using conventional processes.

Stanbery, B.J. [Boeing Defense & Space Group, Seattle, WA (United States)

1994-05-01T23:59:59.000Z

226

Relativistic electron beam generator  

DOE Patents (OSTI)

A relativistic electron beam generator for laser media excitation is described. The device employs a diode type relativistic electron beam source having a cathode shape which provides a rectangular output beam with uniform current density.

Mooney, L.J.; Hyatt, H.M.

1975-11-11T23:59:59.000Z

227

NK Muon Beam  

Science Conference Proceedings (OSTI)

The NK Muon Beam will be a modified version of the existing NT beam line. The decision to employ a modified version of the NT beam line was made based on considerations of cost and availability of the beam line. Preliminary studies considered use of other beam lines, e.g., the NW beam line, and even of moving the bubble chamber with its superconducting coils but were rejected for reasons such as cost, personnel limitations, and potential conflicts with other users.

Koizumi, G.

1988-09-28T23:59:59.000Z

228

Magnetismo Molecular (Molecular Magentism)  

SciTech Connect

The new synthesis processes in chemistry open a new world of research, new and surprising materials never before found in nature can now be synthesized and, as a wonderful result, observed a series of physical phenomena never before imagined. Among these are many new materials the molecular magnets, the subject of this book and magnetic properties that are often reflections of the quantum behavior of these materials. Aside from the wonderful experience of exploring something new, the theoretical models that describe the behavior these magnetic materials are, in most cases, soluble analytically, which allows us to know in detail the physical mechanisms governing these materials. Still, the academic interest in parallel this subject, these materials have a number of properties that are promising to be used in technological devices, such as in computers quantum magnetic recording, magnetocaloric effect, spintronics and many other devices. This volume will journey through the world of molecular magnets, from the structural description of these materials to state of the art research.

Reis, Mario S [Universidade Federal Fluminense, Brasil; Moreira Dos Santos, Antonio F [ORNL

2010-07-01T23:59:59.000Z

229

Improved thermal stability of Ni-silicides on Si: C epitaxial layers  

Science Conference Proceedings (OSTI)

The thermal stability of Ni-silicides on tensily strained in situ P doped Si:C epitaxial layers was evaluated. The baseline Ni silicidation process was shown to be compatible with Si:C Recessed Source-Drain (RSD) stressors for NMOS strain engineering ... Keywords: Epitaxy, Ni, SiC stressors, Silicide, Thermal stability

V. Machkaoutsan; S. Mertens; M. Bauer; A. Lauwers; K. Verheyden; K. Vanormelingen; P. Verheyen; R. Loo; M. Caymax; S. Jakschik; D. Theodore; P. Absil; S. G. Thomas; E. H. A. Granneman

2007-11-01T23:59:59.000Z

230

Stability and charge transfer at the interface between SiC(0001) and epitaxial graphene  

Science Conference Proceedings (OSTI)

Using density functional calculations, we address the energetics of the interface between the SiC(0001) substrate and the first covalently bonded epitaxial graphene layer. We consider a 63x63R30^o geometry showing the experimental periodicity, a simplified ... Keywords: Charge transfer, Energetic stability, Epitaxial graphene, Interfaces, Silicon carbide

Gabriele Sclauzero; Alfredo Pasquarello

2011-07-01T23:59:59.000Z

231

Si-nanoclusters embedded into epitaxial rare earth oxides: Potential candidate for nonvolatile memory applications  

Science Conference Proceedings (OSTI)

Using an unconventional approach, single crystalline Si-nanoclusters (Si-NCs) with uniform size and higher density were embedded into epitaxial rare earth oxide with two-dimensional spatial arrangements at a defined distance from the substrate using ... Keywords: Epitaxial rare earth oxide, MBE, Nonvolatile memory, Si-nanocluster

Apurba Laha; E. Bugiel; A. Fissel; H. J. Osten

2008-12-01T23:59:59.000Z

232

Measurement of beam energy spectrum and impurity content in high-power neutral beam injectors  

DOE Green Energy (OSTI)

The energy spectrum and impurity content of a high-power neutral beam are measured by implanting the beam into high-purity silicon crystals. The depth distribution of the beam particles is then measured by secondary ion mass spectrometry (SIMS); the penetration depth is a function of the incident particle energy. This is one of the few measurement techniques that can determine neutral beam energy components directly. From the results, percentages of atomic and molecular ions in the source plasma can be inferred. Use of deuterium as the source gas provides insight into the role of residual hydrogen in the ion source and accelerating grids and in the SIMS analysis. The principal impurities are carbon and oxygen. Preliminary data indicate that carbon can originate from both methane and carbon monoxide, while oxygen can come from molecular oxygen, carbon monoxide, and water. Results are given and future plans are discussed.

Langley, R.A.; Ryan, P.M.; Tsai, C.C.; Menon, M.M.; Botnick, E.M.; Magee, C.W.

1985-05-01T23:59:59.000Z

233

Engineering the interface between epitaxial lanthanide oxide thin films and Si substrates: a route towards tuning the electrical properties  

Science Conference Proceedings (OSTI)

The impact of interface layer composition on electrical properties of epitaxial Gd"2O"3 thin films on Si(001) substrates have been investigated. The electrical properties of epitaxial Gd"2O"3 thin films were improved significantly by controlled modification ... Keywords: Epitaxy, Gd2O3, High-K, Interface engineering

Apurba Laha; A. Fissel; H. J. Osten

2007-09-01T23:59:59.000Z

234

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

The People of the Molecular Foundry In addition to state-of-the-art instrumentation, Users at the Molecular Foundry benefit from the unique in-house expertise of its researchers....

235

Electronic states in epitaxial graphene fabricated on silicon carbide  

SciTech Connect

An analytical expression for the density of states of a graphene monolayer interacting with a silicon carbide surface (epitaxial graphene) is derived. The density of states of silicon carbide is described within the Haldane-Anderson model. It is shown that the graphene-substrate interaction results in a narrow gap of {approx}0.01-0.06 eV in the density of states of graphene. The graphene atom charge is estimated; it is shown that the charge transfer from the substrate is {approx}10{sup -3}-10{sup -2}e per graphene atom.

Davydov, S. Yu., E-mail: Sergei_Davydov@mail.ru [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation)

2011-08-15T23:59:59.000Z

236

Direct epitaxial growth of InP based heterostructures on SrTiO3/Si(001) crystalline templates  

Science Conference Proceedings (OSTI)

A study of the structural and optical properties of an InAsP/InP quantum well heterostructure grown on a crystalline SrTiO"3 (STO)/Si(001) template is presented. The mismatch between InP and STO is fully accommodated by an array of geometric dislocations ... Keywords: Accommodation, Highly dissimilar systems, Molecular beam epitaxiy, Monolithic integration

G. Saint-Girons; J. Cheng; A. Chettaoui; J. Penuelas; B. Gobaut; P. Regreny; L. Largeau; G. Patriarche; Claude Botella; G. Hollinger

2011-04-01T23:59:59.000Z

237

SUMMARY OF BEAM BEAM OBSERVATIONS DURING STORES IN RHIC.  

Science Conference Proceedings (OSTI)

During stores, the beam-beam interaction has a significant impact on the beam and luminosity lifetimes in RHIC. This was observed in heavy ion, and even more pronounced in proton collisions. Observations include measurements of beam-beam induced tune shifts, lifetime and emittance growth measurements with and without beam-beam interaction, and background rates as a function of tunes. In addition, RHIC is currently the only hadron collider in which strong-strong beam-beam effects can be seen. Coherent beam-beam modes were observed, and suppressed by tune changes. In this article we summarize the most important beam-beam observations made during stores so far.

FISCHER,W.

2003-05-19T23:59:59.000Z

238

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

The Molecular Foundry The Molecular Foundry Lawrence Berkeley National Laboratory One Cyclotron Road Building 67 Berkeley, CA 94720 Screen reader users: click here for plain HTML Go to Google Maps Home Molecular Foundry, Berkeley, CA Loading... Map Sat Ter Did you mean a different: Did you mean a different: Did you mean a different: Add Destination - Show options Hide options Get Directions Note: Public transit coverage may not be available in this area. Molecular Foundry, Berkeley, CA A Molecular Foundry 67 Cyclotron Rd, Berkeley, CA ‎ foundry.lbl.gov 3 reviews · "Berkeley Lab. About the Foundry. What is the Molecular Foundry? Research Themes; Foundry Careers; Media Gallery; Other User Facilities external link; Contact Us" - lbl.gov Directions Search nearby more See all 14 results for Molecular Foundry, Berkeley, CA

239

Optimal doping control of magnetic semiconductors via subsurfactant epitaxy  

SciTech Connect

Dilute magnetic semiconductors (DMS) with high ferromagnetic ordering temperatures (T{sub c}) have vast potential for advancing spin-based electronics or 'spintronics'. To date, achieving high-T{sub c} DMS typically required doping levels of order 5%. Such high doping levels inevitably compromise the structural homogeneity and carrier mobility of the DMS. Here, we establish 'subsurfactant epitaxy' as a novel kinetic pathway for synthesizing Mn-doped germanium with T{sub c} much higher than room temperature, at dramatically reduced doping levels. This is accomplished by optimal control of the diffusion kinetics of the dopant atoms near the growth front in two separate deposition steps. The first involves a submonolayer dose of Mn on Ge(100) at low temperature, which populates subsurface interstitial sites with Mn while suppressing lateral Mn diffusion and clustering. The second step involves epitaxial growth of Ge at elevated temperature, taking advantage of the strong floating ability of the interstitial Mn dopants towards the newly defined subsurface sites at the growth front. Most remarkably, the Mn dopants trapped inside the film are uniformly distributed at substitutional sites, and the resulting film exhibits ferromagnetism above 400 K at the nominal doping level of only 0.2%.

Zeng, Changgan [ORNL; Zhang, Zhenyu [ORNL; van Benthem, Klaus [ORNL; Chisholm, Matthew F [ORNL; Weitering, Harm H [ORNL

2008-01-01T23:59:59.000Z

240

Advances in large-area Hg1-xCdxTe photovoltaic detectors for remote-sensing applications  

Science Conference Proceedings (OSTI)

State-of-the-art large-area photovoltaic (PV) detectors fabricated in HgCdTe grown by molecular beam epitaxy (MBE) have been demonstrated for the Crosstrack Infrared Sounder (CrIS) instrument. Large-area devices (1 mm in diameter) yielded excellent electrical ... Keywords: HgCdTe, crosstrack infrared sounder, molecular beam epitaxy (MBE), photovoltaic detectors, remote sensing

P. S. Wijewarnasuriya; M. Zandian; J. Phillips; D. Edwall; R. E. Dewames; G. Hildebrandt; J. Bajaj; J. M. Arias; A. I. D'Souza; F. Moore

2002-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

Europhys. Lett., 65 (3), pp. 372378 (2004) DOI: 10.1209/epl/i2003-10090-6  

E-Print Network (OSTI)

and orientation. PACS. 61.66.Hq ­ Organic compounds. Abstract. ­ We present a real-time X-ray scattering study of the growth modes in organic molecular-beam epitaxy. We have studied the model system 3,4,9,10-perylene and consequences of our findings for the understanding of the organic molecular-beam epitaxy are discussed. Organic

Schreiber, Frank

242

Selective growth experiments on gallium arsenide (100) surfaces patterned using UV-nanoimprint lithography  

Science Conference Proceedings (OSTI)

We describe a nanoimprint lithography (NIL) process and subsequent solid-source molecular beam epitaxy (SSMBE) growth of III-V semiconductors on patterned substrates. In particular, growth of GaAs, GaInAs, and GaInP, and effects of growth temperature ... Keywords: Molecular beam epitaxy, Nanoimprint lithography, Patterned substrates, Selective growth

A. Tukiainen; J. Viheril; T. Niemi; T. Rytknen; J. Kontio; M. Pessa

2006-12-01T23:59:59.000Z

243

The effects of quantum dot coverage in InAs/(In)GaAs nanostructures for long wavelength emission  

Science Conference Proceedings (OSTI)

We present a study on the effects of quantum dot coverage on the properties of InAs dots embedded in GaAs and in metamorphic In0.15Ga0.85As confining layers grown by molecular beam epitaxy on GaAs substrates. We show that redshifted ... Keywords: Long wavelength emission, Molecular beam epitaxy, Quantum dot ripening, Quantum dots

G. Trevisi; L. Seravalli; P. Frigeri; M. Prezioso; J. C. Rimada; E. Gombia; R. Mosca; L. Nasi; C. Bocchi; S. Franchi

2009-03-01T23:59:59.000Z

244

Improvements of stacked self-assembled InAs/GaAs quantum dot structures for 1.3m applications  

Science Conference Proceedings (OSTI)

We propose the growth of thick 'spacer' layers (d) for high-quality 10-stack InAs/GaAs quantum dots (QDs) emitting at 1.23@mm without the use of strain reduction layers (SRLs). All samples were grown using molecular beam epitaxy (MBE) and extensively ... Keywords: Defect, Molecular beam epitaxy, Stacked quantum dot

J. Ng; M. Missous

2006-12-01T23:59:59.000Z

245

Si Nanostructures Embedded into Crystalline Rare Earth Oxide Matrix for Opto and Nano Electronic Devices  

Science Conference Proceedings (OSTI)

We describe a novel approach to grow Si nanostructures embedded into crystalline rare earth oxides using molecular beam epitaxy. By efficiently exploiting the growth kinetics during growth one could create nanostructures exhibiting various dimensions, ... Keywords: Si quantum dot, quantum confinement, nonvolatile memory, optoelectronics, rare earth oxide, molecular beam epitaxy

H. J. Osten; A. Laha; A. Fissel

2010-02-01T23:59:59.000Z

246

Characterization of polysilicon thin films for MEMS applications  

Science Conference Proceedings (OSTI)

The microstructure of thin polycrystalline films formed by molecular beam epitaxy (MBE) has been studied by transmission electron microscopy (TEM). Beneficial compressive residual stress was introduced by cavitation impacts. Surface morphology was characterized ... Keywords: defects, gavitation, molecular beam epitaxy, polysilicon film, transmission electron microscopy

Dan O. Macodiyo; Hitoshi Soyama; Kazuo Hayashi

2006-07-01T23:59:59.000Z

247

Tevatron beam-beam compensation project progress  

SciTech Connect

In this paper, we report the progress of the Tevatron Beam-Beam Compensation (BBC) project [1]. Electron beam induced proton and antiproton tuneshifts have been reported in [2], suppression of an antiproton emittance growth has been observed, too [1]. Currently, the first electron lens (TEL1) is in operational use as the Tevatron DC beam cleaner. We have made a lot of the upgrades to improve its stability [3]. The 2nd Tevatron electron lens (TEL2) is under the final phase of development and preparation for installation in the Tevatron.

Shiltsev, V.; Zhang, X.L.; Kuznetsov, G.; Pfeffer, H.; Saewert, G.; /Fermilab; Zimmermann, F.; /CERN; Tiunov, M.; /Novosibirsk, IYF; Bishofberger, K.; /UCLA; Bogdanov, I.; Kashtanov, E.; Kozub, S.; Sytnik, V.; Tkachenko, L.; /Serpukhov, IHEP

2005-05-01T23:59:59.000Z

248

ION BEAM COLLIMATOR  

DOE Patents (OSTI)

A device is described for defining a beam of high energy particles wherein the means for defining the beam in the horizontal and vertical dimension are separately adjustable and the defining members are internally cooled. In general, the device comprises a mounting block having a central opening through which the beam is projected, means for rotatably supporting two pairs of beam- forming members, passages in each member for the flow of coolant; the beam- forming members being insulated from each other and the block, and each having an end projecting into the opening. The beam-forming members are adjustable and may be cooperatively positioned to define the beam passing between the end of the members. To assist in projecting and defining the beam, the member ends have individual means connected thereto for indicating the amount of charge collected thereon due to beam interception.

Langsdorf, A.S. Jr.

1957-11-26T23:59:59.000Z

249

Beam position monitor  

DOE Patents (OSTI)

An apparatus for determining the position of an x-ray beam relative to a desired beam axis where the apparatus is positioned along the beam path so that a thin metal foil target intersects the x-ray beam generating fluorescent radiation. A PIN diode array is positioned so that a portion of the fluorescent radiation is intercepted by the array resulting in a series of electrical signals from the PIN diodes making up the array. The signals are then analyzed and the position of the x-ray beam is determined relative to the desired beam path.

Alkire, Randy W.; Rosenbaum, Gerold; Evans, Gwyndaf

2000-09-21T23:59:59.000Z

250

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

SEMINARS ARCHIVE The Molecular Foundry regularly offers seminars and events that feature compelling research and information for those who investigate at the nanoscale. Seminars...

251

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

EVENTS ARCHIVE The Molecular Foundry regularly offers seminars and events that feature compelling research and information for those who investigate at the nanoscale. Seminars...

252

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

efficient energy storage and conversion. Electron donors and acceptors at interfaces Molecular level design and synthesis has created tailor-made electron donors and acceptors...

253

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

Careers Information about current openings at the Molecular Foundry and complete application information is available from LBNL Human Resources. Please follow the application...

254

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

the Future, Atom by Atom Organized into six interdependent research Facilities, The Molecular Foundry, along with Berkeley Lab's additional User programs and affiliated research...

255

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

Sign-Up (Resource Database) Weekly Seminars Users' Executive Committee (UEC) The Molecular Foundry Users' Association is composed of all Foundry Users. Upon beginning work on...

256

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

Management Code of Conduct Conflict Resolution Beginning your project Access to the Molecular Foundry is free of charge for approved, non-proprietary research. (Proprietary...

257

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

SEMINARS The Molecular Foundry regularly offers seminars and events that feature compelling research and information for those who investigate at the nanoscale. Seminars occur on...

258

Beam injection into RHIC  

SciTech Connect

During the RHIC sextant test in January 1997 beam was injected into a sixth of one of the rings for the first time. The authors describe the injection zone and its bottlenecks. They report on the commissioning of the injection system, on beam based measurements of the kickers and the application program to steer the beam.

Fischer, W.; Hahn, H.; MacKay, W.W.; Satogata, T.; Tsoupas, N.; Zhang, W.

1997-07-01T23:59:59.000Z

259

Electron beam device  

DOE Patents (OSTI)

This patent pertains to an electron beam device in which a hollow target is symmetrically irradiated by a high energy, pulsed electron beam about its periphery and wherein the outer portion of the target has a thickness slightly greater than required to absorb the electron beam pulse energy. (auth)

Beckner, E.H.; Clauser, M.J.

1975-08-12T23:59:59.000Z

260

Epitaxial Growth and Characterization of Silicon Carbide Films  

DOE Green Energy (OSTI)

Silicon carbide (SiC) epitaxial layers have been grown in a chemical vapor deposition (CVD) system designed and fabricated in our laboratory. Silicon tetrachloride-propane as well as silane-propane were used as precursor gases. The hot zone was designed based on simulation by using numerical modeling. Growth rates up to 200 {mu}m could be achieved. A new growth-assisted hydrogen etching was developed to show the distribution of the micropipes present in the substrate. Higher growth rate was observed on off-axis (0 0 0 1) 4 H SiC compared to the on-axis (0 0 0 1) wafer and growth mechanism was explained.

Dhanaraj,G.; Dudley, M.; Chen, Y.; Ragothamachar, B.; Wu, B.; Zhang, H.

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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.


261

Three-fold diffraction symmetry in epitaxial graphene and the SiC substrate  

E-Print Network (OSTI)

Epitaxial Graphene and the SiC Substrate D.A. Siegel, 1, 2in graphene ?lms on 6H-SiC(0001) have been studied by lowgrown on the C face of SiC (which possesses azimuthal

Siegel, D A

2010-01-01T23:59:59.000Z

262

AlGaAsSb/GaSb Distributed Bragg Reflectors Grown by Organometallic Vapor Phase Epitaxy  

SciTech Connect

The first AlGaAsSb/GaSb quarter-wave distributed Bragg reflectors grown by metallic vapor phase epitaxy are reported. The peak reflectance is 96% for a 10-period structure.

C.A. Wang; C.J. Vineis; D.R. Calawa

2002-02-13T23:59:59.000Z

263

Epitaxial Ge/Il-V Heterostructures : MOCVD growth, characterization, and applications  

E-Print Network (OSTI)

Epitaxial Ge thin films are being investigated for many important roles in next generation microelectronics. Metal-oxide-semiconductor field effect transistors (MOSFETs) utilizing Ge channels have demonstrated dramatic ...

Bai, Yu, Ph.D. Massachusetts Institute of Technology

2011-01-01T23:59:59.000Z

264

BEAM CONTROL PROBE  

DOE Patents (OSTI)

A probe is described for intercepting a desired portion of a beam of charged particles and for indicating the spatial disposition of the beam. The disclosed probe assembly includes a pair of pivotally mounted vanes moveable into a single plane with adjacent edges joining and a calibrated mechanical arrangement for pivoting the vancs apart. When the probe is disposed in the path of a charged particle beam, the vanes may be adjusted according to the beam current received in each vane to ascertain the dimension of the beam.

Chesterman, A.W.

1959-03-17T23:59:59.000Z

265

Epitaxial VN,,001... Grown and Analyzed In situ by XPS and UPS. II. Analysis of Ar  

E-Print Network (OSTI)

Epitaxial VN,,001... Grown and Analyzed In situ by XPS and UPS. II. Analysis of Ar¿ Sputter Etched-welded to a Mo substrate heater. In Situ Preparation: The epitaxial VN 001 layers were grown in a multichamber that has been shown Ref. 1 to produce sharp 1 1 RHEED patterns. The target, a 5-cm-diam water-cooled V disk

Gall, Daniel

266

EUROv Super Beam Studies  

Science Conference Proceedings (OSTI)

Neutrino Super Beams use conventional techniques to significantly increase the neutrino beam intensity compared to the present neutrino facilities. An essential part of these facilities is an intense proton driver producing a beam power higher than a MW. The protons hit a target able to accept the high proton beam intensity. The produced charged particles are focused by a system of magnetic horns towards the experiment detectors. The main challenge of these projects is to deal with the high beam intensity for many years. New high power neutrino facilities could be build at CERN profiting from an eventual construction of a high power proton driver. The European FP7 Design Study EUROv, among other neutrino beams, studies this Super Beam possibility. This paper will give the latest developments in this direction.

Dracos, Marcos [IPHC, Universite de Strasbourg, CNRS/IN2P3, F-67037 Strasbourg (France)

2011-10-06T23:59:59.000Z

267

Molecular nanocomposites.  

Science Conference Proceedings (OSTI)

The goals of this project are to understand the fundamental principles that govern the formation and function of novel nanoscale and nanocomposite materials. Specific scientific issues being addressed include: design and synthesis of complex molecular precursors with controlled architectures, controlled synthesis of nanoclusters and nanoparticles, development of robust two or three-dimensionally ordered nanocomposite materials with integrated functionalities that can respond to internal or external stimuli through specific molecular interactions or phase transitions, fundamental understanding of molecular self-assembly mechanisms on multiple length scales, and fundamental understanding of transport, electronic, optical, magnetic, catalytic and photocatalytic properties derived from the nanoscale phenomena and unique surface and interfacial chemistry for DOE's energy mission.

Voigt, James A.

2010-03-01T23:59:59.000Z

268

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

is equipped with a variety of tools to aid in work with biomolecules, microbes, molecular biology techniques and cell culture. These tools include: a BioFlo fermentor (14 L),...

269

Strong-strong beam-beam simulation on parallel computer  

DOE Green Energy (OSTI)

The beam-beam interaction puts a strong limit on the luminosity of the high energy storage ring colliders. At the interaction points, the electromagnetic fields generated by one beam focus or defocus the opposite beam. This can cause beam blowup and a reduction of luminosity. An accurate simulation of the beam-beam interaction is needed to help optimize the luminosity in high energy colliders.

Qiang, Ji

2004-08-02T23:59:59.000Z

270

Beam-Gas  

NLE Websites -- All DOE Office Websites (Extended Search)

Gas Gas and Thermal Photon Scattering in the NLC Main Linac as a Source of Beam Halo P. Tenenbaum LCC-Note-0051 12-JAN-2001 Abstract Scattering of primary beam electrons off of residual gas molecules or blackbody radiation photons in the NLC main linac has been identified as a potential source of beam haloes which must be collimated in the beam delivery system. We consider the contributions from four scat- tering mechanisms: inelastic thermal-photon scattering, elastic beam-gas (Coulomb) scattering inelastic beam-gas (Bremsstrahlung) scattering, and atomic-electron scattering. In each case we develop the formalism necessary to estimate the backgrounds generated in the main linac, and determine the expected number of off-energy or large-amplitude particles from each process, assuming a main linac injection energy of 8 GeV and extraction energy of 500 GeV. 1 Introduction The

271

Particle beam injection system  

SciTech Connect

This invention provides a poloidal divertor for stacking counterstreaming ion beams to provide high intensity colliding beams. To this end, method and apparatus are provided that inject high energy, high velocity, ordered, atomic deuterium and tritium beams into a lower energy, toroidal, thermal equilibrium, neutral, target plasma column that is magnetically confined along an endless magnetic axis in a strong restoring force magnetic field having helical field lines to produce counterstreaming deuteron and triton beams that are received bent, stacked and transported along the endless axis, while a poloidal divertor removes thermal ions and electrons all along the axis to increase the density of the counterstreaming ion beams and the reaction products resulting therefrom. By balancing the stacking and removal, colliding, strong focused particle beams, reaction products and reactions are produced that convert one form of energy into another form of energy.

Jassby, Daniel L. (Princeton, NJ); Kulsrud, Russell M. (Princeton, NJ)

1977-01-01T23:59:59.000Z

272

Ion Beam Materials Lab  

NLE Websites -- All DOE Office Websites (Extended Search)

Facilities » Facilities » Ion Beam Materials Lab Ion Beam Materials Lab A new research frontier awaits! Our door is open and we thrive on mutually beneficial partnerships, collaborations that drive innovations and new technologies. April 12, 2012 Ion Beam Danfysik Implanter High Voltage Terminal. Contact Yongqiang Wang (505) 665-1596 Email Devoted to the characterization and modification of surfaces through the use of ion beams The Ion Beam Materials Laboratory (IBML) is a Los Alamos National Laboratory resource devoted to the characterization and modification of surfaces through the use of ion beams. The IBML provides and operates the core facilities, while supporting the design and implementation of specific apparati needed for experiments requested by users of the facility. The result is a facility with

273

Broad beam ion implanter  

DOE Patents (OSTI)

An ion implantation device for creating a large diameter, homogeneous, ion beam is described, as well as a method for creating same, wherein the device is characterized by extraction of a diverging ion beam and its conversion by ion beam optics to an essentially parallel ion beam. The device comprises a plasma or ion source, an anode and exit aperture, an extraction electrode, a divergence-limiting electrode and an acceleration electrode, as well as the means for connecting a voltage supply to the electrodes.

Leung, Ka-Ngo (Hercules, CA)

1996-01-01T23:59:59.000Z

274

BEAMS Crossword Puzzle  

NLE Websites -- All DOE Office Websites (Extended Search)

puzzle with words from the BEAMS Vocabulary List. Download this Activity Lab Pages Puzzle Puzzle Puzzle (cont) Puzzle (cont) Sample AnswersAnswer Key Ansewr Key Ansewr Key...

275

Electron Beam Melting (EBM)  

Science Conference Proceedings (OSTI)

Oct 18, 2011 ... Additive Manufacturing of Metals: Electron Beam Melting (EBM) I Sponsored by: MS&T Organization Program Organizers: Ian D. Harris, EWI;...

276

Electron Beam Melting  

Science Conference Proceedings (OSTI)

Oct 9, 2012 ... Additive Manufacturing of Metals: Electron Beam Melting Program Organizers: Ian Harris, EWI; Ola Harrysson, North Carolina State University;...

277

Molecular Foundry  

NLE Websites -- All DOE Office Websites

Berkeley Lab Berkeley Lab A-Z Index Phone Book Jobs Search DOE Berkeley Lab Berkeley Lab A-Z Index Phone Book Jobs Search DOE About the Foundry What is the Molecular Foundry? Research Themes Foundry Careers Media Gallery Other User Facilities external link Contact Us Go News & Highlights Users People Facilities Imaging and Manipulation Nanofabrication Theory Inorganic Biological Organic NCEM external link Seminars & Events Publications The Molecular Foundry is a Department of Energy-funded nanoscience research facility that provides users from around the world with access to cutting-edge expertise and instrumentation in a collaborative, multidisciplinary environment. Call for Proposals: The next deadline for standard proposals is Through March 31, 2014 Find out more information about becoming a Molecular Foundry facilities User. 2013 Annual User Meeting Postponed - Date TBD

278

Low temperature epitaxial growth of Ge on cube- textured Ni  

SciTech Connect

Quasi- single crystal Ge films were grown on [001]<010> textured Ni substrate at a temperature of 350 oC using an insulating buffer layer of CaF2. A direct deposition of Ge on Ni at 350 oC was shown to alloy with Ni. From x- ray pole figure analysis, it was shown that Ge grew epitaxially with the same orientation as CaF2 and the dispersions in the out- of- plane and in- plane directions were found to be 1.7 0.1o and 6 1o, respectively. In the out- of- plane direction, Ge[111]||CaF2[111]||Ni[001]. In addition, the Ge consisted of four equivalent in- plane oriented domains such that two mutually orthogonal directions: Ge 211 and Ge 011 are parallel to mutually orthogonal directions: Ni 110 and Ni 110 , respectively of the Ni(001) surface. This was shown to be originated from the four equivalent in- plane oriented domains of CaF2 created to minimize the mismatch strain between CaF2 and Ni in those directions.

GIARE, C [Rensselaer Polytechnic Institute (RPI); Palazzo, J [Rensselaer Polytechnic Institute (RPI); Goyal, Amit [ORNL; WANG, G [Rensselaer Polytechnic Institute (RPI); LU, T [Rensselaer Polytechnic Institute (RPI)

2012-01-01T23:59:59.000Z

279

Chemically homogeneous and thermally reversible oxidation of epitaxial graphene  

Science Conference Proceedings (OSTI)

With its exceptional charge mobility, graphene holds great promise for applications in next-generation electronics. In an effort to tailor its properties and interfacial characteristics, the chemical functionalization of graphene is being actively pursued. The oxidation of graphene via the Hummers method is most widely used in current studies, although the chemical inhomogeneity and irreversibility of the resulting graphene oxide compromises its use in high-performance devices. Here, we present an alternative approach for oxidizing epitaxial graphene using atomic oxygen in ultrahigh vacuum. Atomic-resolution characterization with scanning tunnelling microscopy is quantitatively compared to density functional theory, showing that ultrahigh-vacuum oxidization results in uniform epoxy functionalization. Furthermore, this oxidation is shown to be fully reversible at temperatures as low as 260 8C using scanning tunnelling microscopy and spectroscopic techniques. In this manner, ultrahigh-vacuum oxidation overcomes the limitations of Hummers-method graphene oxide, thus creating new opportunities for the study and application of chemically functionalized graphene.

Hossain, Md. Zakir [Northwestern University, Evanston; Johns, James E. [Northwestern University, Evanston; Bevan, Kirk H [ORNL; Karmel, Hunter J. [Northwestern University, Evanston; Liang, Yu Teng [Northwestern University, Evanston; Yoshimoto, Shinya [University of Tokyo, Tokyo, Japan; Mukai, Kozo [University of Tokyo, Tokyo, Japan; Koitaya, Tatanori [University of Tokyo, Tokyo, Japan; Yoshinobu, Jun [University of Tokyo, Tokyo, Japan; Kawai, Maki [University of Tokyo, Tokyo, Japan; Lear, Amanda M. [Indiana University; Kesmodel, Larry L. [Indiana University; Tait, Steven L. [Indiana University; Hersam, Mark C. [Northwestern University, Evanston

2012-01-01T23:59:59.000Z

280

Substrate misorientation effects on epitaxial GaInAsSb  

DOE Green Energy (OSTI)

The effect of substrate misorientation on the growth of GaInAsSb was studied for epilayers grown lattice-matched to GaSb substrates by low-pressure organometallic vapor phase epitaxy. The substrates were (100) misoriented 2 or 6{degree} toward (110), (111)A, or (111)B. The surface is mirror-like and featureless for layers grown with a 6{degree} toward (111)B misorientation, while, a slight texture was observed for layers grown on all other misorientations. The optical quality of layers, as determined by the full width at half-maximum of photoluminescence spectra measured at 4K, is significantly better for layers grown on substrates with a 6{degree} toward (111)B misorientation. The incorporation of Zn as a p-type dopant in GaInAsSb is about 1.5 times more efficient on substrates with 6{degree} toward (111)B misorientation compared to 2{degree} toward (110) misorientation. The external quantum efficiency of thermophotovoltaic devices is not, however, significantly affected by substrate misorientation.

Wang, C.A.; Choi, H.K.; Oakley, D.C. [Massachusetts Inst. of Tech., Lexington, MA (United States). Lincoln Lab.; Charache, G.W. [Lockheed Martin Corp., Schenectady, NY (United States)

1997-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

Laser beam generating apparatus  

DOE Patents (OSTI)

Laser beam generating apparatus including a septum segment disposed longitudinally within the tubular structure of the apparatus. The septum provides for radiatively dissipating heat buildup within the tubular structure and for generating relatively uniform laser beam pulses so as to minimize or eliminate radial pulse delays (the chevron effect). 11 figures.

Warner, B.E.; Duncan, D.B.

1993-12-28T23:59:59.000Z

282

Laser beam generating apparatus  

DOE Patents (OSTI)

Laser beam generating apparatus including a septum segment disposed longitudinally within the tubular structure of the apparatus. The septum provides for radiatively dissipating heat buildup within the tubular structure and for generating relatively uniform laser beam pulses so as to minimize or eliminate radial pulse delays (the chevron effect).

Warner, Bruce E. (Livermore, CA); Duncan, David B. (Auburn, CA)

1994-01-01T23:59:59.000Z

283

Laser beam generating apparatus  

DOE Patents (OSTI)

Laser beam generating apparatus including a septum segment disposed longitudinally within the tubular structure of the apparatus is described. The septum provides for radiatively dissipating heat buildup within the tubular structure and for generating relatively uniform laser beam pulses so as to minimize or eliminate radial pulse delays (the chevron effect). 7 figures.

Warner, B.E.; Duncan, D.B.

1994-02-15T23:59:59.000Z

284

Laser beam generating apparatus  

DOE Patents (OSTI)

Laser beam generating apparatus including a septum segment disposed longitudinally within the tubular structure of the apparatus. The septum provides for radiatively dissipating heat buildup within the tubular structure and for generating relatively uniform laser beam pulses so as to minimize or eliminate radial pulse delays (the chevron effect).

Warner, Bruce E. (Livermore, CA); Duncan, David B. (Auburn, CA)

1993-01-01T23:59:59.000Z

285

Beam Diagnostics for FACET  

SciTech Connect

FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration beginning in summer 2011. The nominal FACET parameters are 23GeV, 3nC electron bunches compressed to about 20 {micro}m long and focussed to about 10 {micro}m wide. Characterization of the beam-plasma interaction requires complete knowledge of the incoming beam parameters on a pulse-to-pulse basis. FACET diagnostics include Beam Position Monitors, Toroidal current monitors, X-ray and Cerenkov based energy spectrometers, optical transition radiation (OTR) profile monitors and coherent transition radiation (CTR) bunch length measurement systems. The compliment of beam diagnostics and their expected performance are reviewed. Beam diagnostic measurements not only provide valuable insights to the running and tuning of the accelerator but also are crucial for the PWFA experiments in particular. Beam diagnostic devices are being set up at FACET and will be ready for beam commissioning in summer 2011.

Li, S.Z.; Hogan, M.J.; /SLAC

2011-08-19T23:59:59.000Z

286

Laser beam alignment system  

DOE Patents (OSTI)

A plurality of pivotal reflectors direct a high-power laser beam onto a workpiece, and a rotatable reflector is movable to a position wherein it intercepts the beam and deflects a major portion thereof away from its normal path, the remainder of the beam passing to the pivotal reflectors through an aperture in the rotating reflector. A plurality of targets are movable to positions intercepting the path of light traveling to the pivotal reflectors, and a preliminary adjustment of the latter is made by use of a low-power laser beam reflected from the rotating reflector, after which the same targets are used to make a final adjustment of the pivotal reflectors with the portion of the high-power laser beam passed through the rotating reflector.

Kasner, William H. (11686 Althea Dr., Pittsburgh, PA 15235); Racki, Daniel J. (712 Union Cemetery Rd., Greensburg, PA 15601); Swenson, Clark E. (228 Scott Dr., Monroeville, PA 15146)

1984-01-01T23:59:59.000Z

287

Beam director design report  

Science Conference Proceedings (OSTI)

A design and fabrication effort for a beam director is documented. The conceptual design provides for the beam to pass first through a bending and focusing system (or ''achromat''), through a second achromat, through an air-to-vacuum interface (the ''beam window''), and finally through the vernier steering system. Following an initial concept study for a beam director, a prototype permanent magnet 30/sup 0/ beam-bending achromat and prototype vernier steering magnet were designed and built. In volume II, copies are included of the funding instruments, requests for quotations, purchase orders, a complete set of as-built drawings, magnetic measurement reports, the concept design report, and the final report on the design and fabrication project. (LEW)

Younger, F.C.

1986-08-01T23:59:59.000Z

288

First Beam to FACET  

Science Conference Proceedings (OSTI)

The SLAC 3km linear electron accelerator has been reconfigured to provide a beam of electrons to the new Facility for Advanced Accelerator Experimental Tests (FACET) while simultaneously providing an electron beam to the Linac Coherent Light Source (LCLS). On June 23, 2011, the first electron beam was transported through this new facility. Commissioning of FACET is in progress. On June 23, 2011, an electron beam was successfully transported through the new FACET system to a dump in Sector 20 in the linac tunnel. This was achieved while the last third of the linac, operating from the same control room, but with a separate injector system, was providing an electron beam to the Linac Coherent Light Source (LCLS), demonstrating that concurrent operation of the two facilities is practical. With the initial checkout of the new transport line essentially complete, attention is now turning toward compressing the electron bunches longitudinally and focusing them transversely to support a variety of accelerator science experiments.

Erickson, R.; Clarke, C.; Colocho, W.; Decker, F.-J.; Hogan, M.; Kalsi, S.; Lipkowitz, N.; Nelson, J.; Phinney, N.; Schuh, P.; Sheppard, J.; Smith, H.; Smith, T.; Stanek, M.; Turner, J.; Warren, J.; Weathersby, S.; Wienands, U.; Wittmer, W.; Woodley, M.; Yocky, G.; /SLAC

2011-12-13T23:59:59.000Z

289

B13+: Photodriven Molecular Wankel Engine  

Science Conference Proceedings (OSTI)

Synthetic molecular motors that are capable of delivering controlled movement upon energy input are one of the key building blocks in nanomachinery. The major energy sources of molecular motors are from chemical reactions, photon beams, or electric current, which are converted into mechanical forces through the excitation of the electronic states of the molecule. The energy scale of the electronic excitation is normally two orders of magnitude larger than the molecular vibrational frequencies. To reduce the heat dissipation and increase the energy utilization efficiency, a motor running purely on the electronic ground-state (GS) potential energy surfaces is highly desirable.

Zhang, Jin; Sergeeva, Alina P.; Sparta, Manuel; Alexandrova, Anastassia N.

2012-07-09T23:59:59.000Z

290

SPEAR3 Beam Line Availability  

NLE Websites -- All DOE Office Websites (Extended Search)

Beam Line Support | Floor Support | Administrative Support SPEAR3 Beam Line Availability Beam Line BL Type Technique(s) Status 1-4 X-ray Small and Wide Angle X-ray Scattering Open...

291

Chemical Vapor Deposition of Silicon Carbide Epitaxial Films and their Characterization  

DOE Green Energy (OSTI)

A chemical vapor deposition (CVD) system was designed and fabricated in our laboratory and SiC homo-epitaxial layers were grown in the CVD process using silicon tetrachloride and propane precursors with hydrogen as a carrier gas. The temperature field was generated using numerical modeling. Gas flow rates, temperature field, and the gradients are found to influence the growth rates of the epitaxial layers. Growth rates were found to increase as the temperature increased at high carrier gas flow rate, while at lower carrier gas flow rate, growth rates were observed to decrease as the temperature increased. Based on the equilibrium model, 'thermodynamically controlled growth' accounts for the growth rate reduction. The grown epitaxial layers were characterized using various techniques. Reduction in the threading screw dislocation (SD) density in the epilayers was observed. Suitable models were developed for explaining the reduction in the SD density as well as the conversion of basal plane dislocations (BPDs) into threading edge dislocations (TEDs).

Dhanaraj,G.; Chen, Y.; Dudley, M.; Cai, D.; Zhang, H.

2007-01-01T23:59:59.000Z

292

Method for rapid, controllable growth and thickness, of epitaxial silicon films  

DOE Patents (OSTI)

A method of producing epitaxial silicon films on a c-Si wafer substrate using hot wire chemical vapor deposition by controlling the rate of silicon deposition in a temperature range that spans the transition from a monohydride to a hydrogen free silicon surface in a vacuum, to obtain phase-pure epitaxial silicon film of increased thickness is disclosed. The method includes placing a c-Si substrate in a HWCVD reactor chamber. The method also includes supplying a gas containing silicon at a sufficient rate into the reaction chamber to interact with the substrate to deposit a layer containing silicon thereon at a predefined growth rate to obtain phase-pure epitaxial silicon film of increased thickness.

Wang, Qi (Littleton, CO); Stradins, Paul (Golden, CO); Teplin, Charles (Boulder, CO); Branz, Howard M. (Boulder, CO)

2009-10-13T23:59:59.000Z

293

Electron and laser beam welding  

SciTech Connect

This book contains 22 selections. Some of the titles are: Laser welding of chandelles to the plates of the sommier employed in the nuclear power plant core; Electron beam welding of hobbing cutters; Sealing welds in electron beam welding of thick metals; Development and application of high power electron beam welding; Electron beam welding of dissimilar metals (niobium, molybdenum, porous tungsten-molybdenum); Status of electron beam welding in the United States of America; and Electron and laser beam welding in Japan.

1986-01-01T23:59:59.000Z

294

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

See the Foundry's full equipment list See the Foundry's full equipment list Organic and Macromolecular Synthesis Capabilities & Tools Major Instruments and Capabilities AB SCIEX TF4800 MALDI TOF-TOF Mass Spectrometer This instrument is the tandem time-of-flight mass spectrometer systems, providing the excellent level of molecular mass coverage in the range of molecular masses 500 and 150,000 Da, high throughput, and confidence in both qualitative and quantitative analyses. The analyzer combines all of the advantages of MALDI in a flexible, easy-to-use, ultra-high-performance mass spectrometer with all the advanced capabilities of software. On-axis laser provides high sensitivity to identify and quantitate low-abundance compounds in complex samples. High-resolution precursor ion selection lets

295

Challenges in Accelerator Beam Instrumentation  

E-Print Network (OSTI)

The challenges in beam instrumentation and diagnostics for present and future particle accelerator projects are presented. A few examples for advanced hadron and lepton beam diagnostics are given.

Wendt, M

2009-01-01T23:59:59.000Z

296

Challenges in Accelerator Beam Instrumentation  

Science Conference Proceedings (OSTI)

The challenges in beam instrumentation and diagnostics for present and future particle accelerator projects are presented. A few examples for advanced hadron and lepton beam diagnostics are given.

Wendt, M.

2009-12-01T23:59:59.000Z

297

Frontiers of Particle Beam Physics  

E-Print Network (OSTI)

Low Emittance e--e+ Beams, Brookhaven National Laboratory,Island, NY, October 1988, Brookhaven National Laboratory,Low Emittance e--e+ Beams, Brookhaven National Laboratory,

Sessler, Andrew M.

2008-01-01T23:59:59.000Z

298

NEWTON's Molecular Biology Videos  

NLE Websites -- All DOE Office Websites (Extended Search)

Molecular Biology Videos Do you have a great molecular biology video? Please click our Ideas page. Featured Videos: University of Berkeley - Molecular Biology Lectures University...

299

Simulations of beam-beam and beam-wire interactions in RHIC  

SciTech Connect

The beam-beam interaction is one of the dominant sources of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and strong localized long-range beam-beam effects are experimentally investigated in the RHIC collider. Tune shift, beam transfer function, and beam loss rate are measured in dedicated experiments. In this paper, they report on simulations to study the effect of beam-wire interactions based on diffusive apertures, beam loss rates, and beam transfer function using a parallelized weak-strong beam simulation code (BBSIMC). The simulation results are compared with measurements performed in RHIC during 2007 and 2008.

Kim, Hyung J.; Sen, Tanaji; /Fermilab; Abreu, Natalia P.; Fischer, Wolfram; /Brookhaven

2009-02-01T23:59:59.000Z

300

Process for forming epitaxial perovskite thin film layers using halide precursors  

DOE Patents (OSTI)

A process for forming an epitaxial perovskite-phase thin film on a substrate. This thin film can act as a buffer layer between a Ni substrate and a YBa.sub.2 Cu.sub.3 O.sub.7-x superconductor layer. The process utilizes alkali or alkaline metal acetates dissolved in halogenated organic acid along with titanium isopropoxide to dip or spin-coat the substrate which is then heated to about 700.degree. C. in an inert gas atmosphere to form the epitaxial film on the substrate. The YBCO superconductor can then be deposited on the layer formed by this invention.

Clem, Paul G. (Albuquerque, NM); Rodriguez, Mark A. (Albuquerque, NM); Voigt, James A. (Corrales, NM); Ashley, Carol S. (Albuquerque, NM)

2001-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

Simulation study of beam-beam effects in ion beams with large space charge tuneshift  

Science Conference Proceedings (OSTI)

During low-energy operations with gold-gold collisions at 3.85 GeV beam energy, significant beam lifetime reductions have been observed due to the beam-beam interaction in the presence of large space charge tuneshifts. These beam-beam tuneshift parameters were about an order of magnitude smaller than during regular high energy operations. To get a better understanding of this effect, simulations have been performed. Recent results are presented.

Montag C.

2012-05-20T23:59:59.000Z

302

Neutral particle beam intensity controller  

DOE Patents (OSTI)

The neutral beam intensity controller is based on selected magnetic defocusing of the ion beam prior to neutralization. The defocused portion of the beam is dumped onto a beam dump disposed perpendicular to the beam axis. Selective defocusing is accomplished by means of a magnetic field generator disposed about the neutralizer so that the field is transverse to the beam axis. The magnetic field intensity is varied to provide the selected partial beam defocusing of the ions prior to neutralization. The desired focused neutral beam portion passes along the beam path through a defining aperture in the beam dump, thereby controlling the desired fraction of neutral particles transmitted to a utilization device without altering the kinetic energy level of the desired neutral particle fraction. By proper selection of the magnetic field intensity, virtually zero through 100% intensity control of the neutral beam is achieved.

Dagenhart, W.K.

1984-05-29T23:59:59.000Z

303

Courses on Beam Physics  

NLE Websites -- All DOE Office Websites (Extended Search)

Beam Physics Beam Physics The following is an incomplete listing of course available for beam physics. United States Particle Accelerator School The US Particle Accelerator School provides educational programs in the field of beams and their associated accelerator technologies not otherwise available to the community of science and technology. Joint Universities Accelerator School Each year JUAS provides a foundation course on accelerator physics and associated technologies. The US-CERN-Japan-Russia Joint Accelerator School The purpose of the US-CERN-Japan-Russia joint school is to better our relations by working together on an advanced topical course every two years, alternating between the U.S., western Europe, Japan and Russia. The last set of courses focused on the frontiers of accelerator technology in

304

1996 Beam Instrumentation Workshop  

NLE Websites -- All DOE Office Websites (Extended Search)

1996 Beam Instrumentation Workshop BIW '96 logo The Advanced Photon Source (APS) Argonne National Laboratory May 6-9, 1996 Dear Colleague: It is my pleasure to invite you to the...

305

BNL | ATF Beam Schedule  

NLE Websites -- All DOE Office Websites (Extended Search)

Beam Schedule (pdf) Beam Schedule (pdf) Sunday Monday Tuesday Wednesday Thursday Friday Saturday 22 1/2 Holiday Holiday 28 January Holiday 4 5 Maintenance 11 12 Maintenance 18 19 Holiday AE52 - DWFA (Euclid), BL2 25 February AE52 - DWFA (Euclid), BL2 1 2 AE50 - PWFA in QNR (UCLA), BL2 8 9 AE50 - PWFA in QNR (UCLA), BL2 15 16 Holiday AE50 - PWFA in QNR (UCLA), BL2 22 March 1 2 AE53 - Nonlinear Compton (UCLA) 8 9 AE53 - Nonlinear Compton (UCLA) 15 16 AE53 - Nonlinear Compton (UCLA) 22 23 29 Sunday Monday Tuesday Wednesday Thursday Friday Saturday User operations (E-beam in use) Ions - Ion generation User operations (laser in use) PWFA - Plasma Wakefield Acceleration User operations (E-beam and laser in use)

306

Intense ion beam generator  

DOE Patents (OSTI)

Methods and apparatus for producing intense megavolt ion beams are disclosed. In one embodiment, a reflex triode-type pulsed ion accelerator is described which produces ion pulses of more than 5 kiloamperes current with a peak energy of 3 MeV. In other embodiments, the device is constructed so as to focus the beam of ions for high concentration and ease of extraction, and magnetic insulation is provided to increase the efficiency of operation.

Humphries, Jr., Stanley (Ithaca, NY); Sudan, Ravindra N. (Ithaca, NY)

1977-08-30T23:59:59.000Z

307

Beam/seam alignment control for electron beam welding  

DOE Patents (OSTI)

This invention relates to a dynamic beam/seam alignment control system for electron beam welds utilizing video apparatus. The system includes automatic control of workpiece illumination, near infrared illumination of the workpiece to limit the range of illumination and camera sensitivity adjustment, curve fitting of seam position data to obtain an accurate measure of beam/seam alignment, and automatic beam detection and calculation of the threshold beam level from the peak beam level of the preceding video line to locate the beam or seam edges.

Burkhardt, Jr., James H. (Knoxville, TN); Henry, J. James (Oak Ridge, TN); Davenport, Clyde M. (Knoxville, TN)

1980-01-01T23:59:59.000Z

308

Small Spot, Brighter Beam  

NLE Websites -- All DOE Office Websites (Extended Search)

Small Spot, Brighter Beam Small Spot, Brighter Beam Small Spot, Brighter Beam Print Do you notice the brighter beam? During the most recent shutdown, all of the corrector magnets were replaced with sextupoles, reducing the horizontal emittance and increasing beam brightness. "This is part of ongoing improvement to keep the ALS on the cutting edge," says Alastair MacDowell, a beamline scientist on Beamline 12.2.2. The brightness has increased by a factor of about three in the storage ring. Beamlines on superbend or center-bend magnets will see the most noticeable increase in brightness, but the horizontal beam size and divergence have been substantially reduced at all beamlines. "We are starting to approach the resolution of many beamlines. Therefore, not every beamline will be able to resolve the full improvement," says Christoph Steier, project leader of the brightness upgrade. Though superbend and center-bend magnet source sizes are reduced by roughly a factor of three, "measured improvements so far range from a factor of 2-2.5," Steier says. He and MacDowell agree that the beamline optics are likely the limiting factor in resolving the full improvement at the beamlines.

309

Wire Scanner Beam Profile Measurements: LANSCE Facility Beam Development  

SciTech Connect

The Los Alamos Neutron Science Center (LANSCE) is replacing Wire Scanner (WS) beam profile measurement systems. Three beam development tests have taken place to test the new wire scanners under beam conditions. These beam development tests have integrated the WS actuator, cable plant, electronics processors and associated software and have used H{sup -} beams of different beam energy and current conditions. In addition, the WS measurement-system beam tests verified actuator control systems for minimum profile bin repeatability and speed, checked for actuator backlash and positional stability, tested the replacement of simple broadband potentiometers with narrow band resolvers, and tested resolver use with National Instruments Compact Reconfigurable Input and Output (cRIO) Virtual Instrumentation. These beam tests also have verified how trans-impedance amplifiers react with various types of beam line background noise and how noise currents were not generated. This paper will describe these beam development tests and show some resulting data.

Gilpatrick, John D. [Los Alamos National Laboratory; Batygin, Yuri K. [Los Alamos National Laboratory; Gonzales, Fermin [Los Alamos National Laboratory; Gruchalla, Michael E. [Los Alamos National Laboratory; Kutac, Vincent G. [Los Alamos National Laboratory; Martinez, Derwin [Los Alamos National Laboratory; Sedillo, James Daniel [Los Alamos National Laboratory; Pillai, Chandra [Los Alamos National Laboratory; Rodriguez Esparza, Sergio [Los Alamos National Laboratory; Smith, Brian G. [Los Alamos National Laboratory

2012-05-15T23:59:59.000Z

310

Molecular Phylogeny Reconstruction  

E-Print Network (OSTI)

Molecular Phylogeny Reconstruction Sudhir Kumar, Arizona State University, Tempe, Arizona, USA Alan Filipski, Arizona State University, Tempe, Arizona, USA Molecular phylogenetics deals with the inference molecular data. By modelling patterns of molecular change in protein and deoxyribonucleic acid (DNA

Kumar, Sudhir

311

SIMULATION STUDY OF THREE-DIMENSIONAL LASER COOLING SCHEMES FOR FAST STORED BEAMS  

SciTech Connect

Molecular dynamics (MD) approach is employed to study laser cooling of fast circulating beams in a storage ring. The authors compare several three-dimensional (3D) cooling methods, examining achievable minimum beam temperature. In particular, the stress is put upon the three coupling schemes, i.e. the dispersion-coupling scheme, the coupling-cavity scheme, and the tapered cooling scheme. The authors show that beam temperatures much lower than the currently achievable level could be reached with these schemes.

KIHARA,T.; OKAMOTO,H.; IWASHITA,Y.; OIDE,K.; LAMANNA,G.; WEI,J.

1998-06-22T23:59:59.000Z

312

Low energy electron beam induced vacancy activation in GaN  

Science Conference Proceedings (OSTI)

Experimental evidence on low energy electron beam induced point defect activation in GaN grown by metal-organic vapor phase epitaxy (MOVPE) is presented. The GaN samples are irradiated with a 5-20 keV electron beam of a scanning electron microscope and investigated by photoluminescence and positron annihilation spectroscopy measurements. The degradation of the band-to-band luminescence of the irradiated GaN films is associated with the activation of point defects. The activated defects were identified as in-grown Ga-vacancies. We propose that MOVPE-GaN contains a significant concentration of passive V{sub Ga}-H{sub n} complexes that can be activated by H removal during low energy electron irradiation.

Nykaenen, H.; Suihkonen, S.; Sopanen, M. [Department of Micro- and Nanosciences, Aalto University, P.O. Box 13500, FI-00076 Aalto (Finland); Kilanski, L. [Department of Applied Physics, Aalto University, P.O. Box 11100, FI-00076 Aalto (Finland); Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/56, 02-668 Warsaw (Poland); Tuomisto, F. [Department of Applied Physics, Aalto University, P.O. Box 11100, FI-00076 Aalto (Finland)

2012-03-19T23:59:59.000Z

313

Single element laser beam shaper  

DOE Patents (OSTI)

A single lens laser beam shaper for converting laser beams from any spatial profile to a flat-top or uniform spatial profile. The laser beam shaper includes a lens having two aspheric surfaces. The beam shaper significantly simplifies the overall structure in comparison with conventional 2-element systems and therefore provides great ease in alignment and reduction of cost.

Zhang, Shukui (Yorktown, VA); Michelle D. Shinn (Newport News, VA)

2005-09-13T23:59:59.000Z

314

Electron Beam Powder Bed Processes  

Science Conference Proceedings (OSTI)

Advanced Materials, Processes and Applications for Additive Manufacturing : Electron Beam Powder Bed Processes Program Organizers: Andrzej...

315

Characterization of Epitaxial Film Silicon Solar Cells Grown on Seeded Display Glass: Preprint  

DOE Green Energy (OSTI)

We report characterizations of epitaxial film crystal silicon (c-Si) solar cells with open-circuit voltages (Voc) above 560 mV. The 2-um absorber cells are grown by low-temperature (<750 degrees C) hot-wire CVD (HWCVD) on Corning EAGLE XG display glass coated with a layer-transferred (LT) Si seed. The high Voc is a result of low-defect epitaxial Si (epi-Si) growth and effective hydrogen passivation of defects. The quality of HWCVD epitaxial growth on seeded glass substrates depends on the crystallographic quality of the seed and the morphology of the epitaxial growth surface. Heterojunction devices consist of glass/c-Si LT seed/ epi n+ Si:P/epi n- Si:P/intrinsic a-Si:H/p+ a-Si:H/ITO. Similar devices grown on electronically 'dead' n+ wafers have given Voc {approx}630 mV and {approx}8% efficiency with no light trapping features. Here we study the effects of the seed surface polish on epi-Si quality, how hydrogenation influences the device character, and the dominant junction transport physics.

Young, D. L.; Grover, S.; Teplin, C.; Stradins, P.; LaSalvia, V.; Chuang, T. K.; Couillard, J. G.; Branz, H. M.

2012-06-01T23:59:59.000Z

316

Characterization of Epitaxial Film Silicon Solar Cells Grown on Seeded Display Glass: Preprint  

Science Conference Proceedings (OSTI)

We report characterizations of epitaxial film crystal silicon (c-Si) solar cells with open-circuit voltages (Voc) above 560 mV. The 2-um absorber cells are grown by low-temperature (EAGLE XG display glass coated with a layer-transferred (LT) Si seed. The high Voc is a result of low-defect epitaxial Si (epi-Si) growth and effective hydrogen passivation of defects. The quality of HWCVD epitaxial growth on seeded glass substrates depends on the crystallographic quality of the seed and the morphology of the epitaxial growth surface. Heterojunction devices consist of glass/c-Si LT seed/ epi n+ Si:P/epi n- Si:P/intrinsic a-Si:H/p+ a-Si:H/ITO. Similar devices grown on electronically 'dead' n+ wafers have given Voc {approx}630 mV and {approx}8% efficiency with no light trapping features. Here we study the effects of the seed surface polish on epi-Si quality, how hydrogenation influences the device character, and the dominant junction transport physics.

Young, D. L.; Grover, S.; Teplin, C.; Stradins, P.; LaSalvia, V.; Chuang, T. K.; Couillard, J. G.; Branz, H. M.

2012-06-01T23:59:59.000Z

317

Fabrication of magnetic tunnel junctions with epitaxial and textured ferromagnetic layers  

DOE Patents (OSTI)

This invention relates to magnetic tunnel junctions and methods for making the magnetic tunnel junctions. The magnetic tunnel junctions include a tunnel barrier oxide layer sandwiched between two ferromagnetic layers both of which are epitaxial or textured with respect to the underlying substrate upon which the magnetic tunnel junctions are grown. The magnetic tunnel junctions provide improved magnetic properties, sharper interfaces and few defects.

Chang, Y. Austin (Middleton, WI); Yang, Jianhua Joshua (Madison, WI)

2008-11-11T23:59:59.000Z

318

Reducing dislocations in semiconductors utilizing repeated thermal cycling during multistage epitaxial growth  

DOE Patents (OSTI)

Dislocation densities are reduced in growing semiconductors from the vapor phase by employing a technique of interrupting growth, cooling the layer so far deposited, and then repeating the process until a high quality active top layer is achieved. The method of interrupted growth, coupled with thermal cycling, permits dislocations to be trapped in the initial stages of epitaxial growth.

Fan, John C. C. (Chestnut Hill, MA); Tsaur, Bor-Yeu (Arlington, MA); Gale, Ronald P. (Bedford, MA); Davis, Frances M. (Framingham, MA)

1992-02-25T23:59:59.000Z

319

Reducing dislocations in semiconductors utilizing repeated thermal cycling during multistage epitaxial growth  

DOE Patents (OSTI)

Dislocation densities are reduced in growing semiconductors from the vapor phase by employing a technique of interrupting growth, cooling the layer so far deposited, and then repeating the process until a high quality active top layer is achieved. The method of interrupted growth, coupled with thermal cycling, permits dislocations to be trapped in the initial stages of epitaxial growth.

Fan, John C. C. (Chestnut Hill, MA); Tsaur, Bor-Yeu (Arlington, MA); Gale, Ronald P. (Bedford, MA); Davis, Frances M. (Framingham, MA)

1986-12-30T23:59:59.000Z

320

Ultrahigh growth rate of epitaxial silicon by chemical vapor deposition at low temperature with neopentasilane  

E-Print Network (OSTI)

- iane SiH4 to disilane Si2H6 , to trisilane, Si3H8 2 leads to increased epitaxy growth rates at the same growth rate was 0.6 nm/min, and the disilane growth rate was 8 nm/min. In this work, we explored the use

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321

From Molecular Computing to Molecular Programming  

E-Print Network (OSTI)

From Molecular Computing to Molecular Programming Masami Hagiya Graduate School of Science of the Japanese Molecular Computer Project, and foresee the future of the #12;eld. In addition to describing the major achievements of the project, Suyama's Dynamic Programming Molecular Computer and Sakamoto

Hagiya, Masami

322

Beam Characterizations at Femtosecond Electron Beam Facility  

SciTech Connect

The SURIYA project at the Fast Neutron Research Facility (FNRF) has been established and is being commissioning to generate femtosecond (fs) electron bunches. Theses short bunches are produced by a system consisting of an S-band thermionic cathode RF-gun, an alpha magnet (a-magnet) serving as a magnetic bunch compressor, and a SLAC-type linear accelerator (linac). The characteristics of its major components and the beam characterizations as well as the preliminary experimental results will be presented and discussed in this paper.

Rimjaem, S.; Jinamoon, V.; Kangrang, M.; Kusoljariyakul, K.; Saisut, J.; Thongbai, C.; Vilaithong, T.; Rhodes, M.W.; Wichaisirimongkol, P.; /Chiang Mai U.; Wiedemann, H.; /SLAC

2006-03-17T23:59:59.000Z

323

ICFA Beam Dynamics Newsletter  

SciTech Connect

The Collider-Accelerator Department at Brookhaven National Laboratory is building a high-brightness 500 mA capable Energy Recovery Linac (ERL) as one of its main R&D thrusts towards eRHIC, the polarized electron - hadron collider as an upgrade of the operating RHIC facility. The ERL is in final assembly stages, with injection commisioning starting in October 2012. The objective of this ERL is to serve as a platform for R&D into high current ERL, in particular issues of halo generation and control, Higher-Order Mode (HOM) issues, coherent emissions for the beam and high-brightness, high-power beam generation and preservation. The R&D ERL features a superconducting laser-photocathode RF gun with a high quantum efficiency photoccathode served with a load-lock cathode delivery system, a highly damped 5-cell accelerating cavity, a highly flexible single-pass loop and a comprehensive system of beam instrumentation. In this ICFA Beam Dynamics Newsletter article we will describe the ERL in a degree of detail that is not usually found in regular publications. We will discuss the various systems of the ERL, following the electrons from the photocathode to the beam dump, cover the control system, machine protection etc and summarize with the status of the ERL systems.

Ben-Zvi I.; Kuczewski A.; Altinbas, Z.; Beavis, D.; Belomestnykh,; Dai, J. et al

2012-07-01T23:59:59.000Z

324

Booster gold beam injection efficiency and beam loss  

SciTech Connect

The Relativistic Heavy Ion Collider (RHIC) at the BNL requires the AGS to provide gold beam with the intensity of 10{sup 9} ions per bunch. Over the years, the Tandem Van de Graaff has provided steadily increasing intensity of gold ion beams to the AGS Booster. However, the gold ion beam injection efficiency at the Booster has been found to decrease with the rising intensity of injected beams. As the result, for Tandem beams of the highest intensity, the Booster late intensity is lower than with slightly lower intensity Tandem beam. In this article, the authors present two experiments associated with the Booster injection efficiency and beam intensity. One experiment looks at the Booster injection efficiency by adjusting the Tandem beam intensity, and another looks at the beam life time while scraping the beam in the Booster. The studies suggest that the gold beam injection efficiency at the AGS Booster is related to the beam loss in the ring, rather than the intensity of injected beam or circulating beam.

Zhang, S.Y.; Ahrens, L.A.

1998-08-01T23:59:59.000Z

325

CROSSED MOLECULAR BEAM STUDIES OF UN-IMOLECULAR REACTION DYNAMICS  

E-Print Network (OSTI)

released in carbon-chlorine bond formation to redistributeIn the reaction of chlorine and fluorine atoms with vinylthe reaction of The reaction chlorine atoms with 1, 2 and 3-

Buss, R.J.

2010-01-01T23:59:59.000Z

326

Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

Theory of Nanostructured Materials Theory of Nanostructured Materials The Theory of Nanostructured Materials Facility at the Molecular Foundry is focused on expanding our understanding of materials at the nanoscale. Our research connects the structural and dynamical properties of materials to their functions, such as electrical conductivity and storage, light-harvesting for electricity and fuel, or gas separation and sequestration. We develop and employ a broad range of tools, including advanced electronic-structure theory, excited-state methods, model Hamiltonians, and statistical mechanical models. This combination of approaches reveals how materials behave at the nanoscale, in pursuit of materials and devices that meet global energy and sustainability needs. Electronic structure of complex materials and interfaces for energy

327

Beam-Based Alignment  

NLE Websites -- All DOE Office Websites (Extended Search)

One: One: Single-Bunch Comparative Study of Three Algorithms Peter Tenenbaum LCC-Note-0013 17-February-1999 Abstract We describe the results of a series of simulation studies of beam-based alignment of the NLC main linacs using the program LIAR. Three algorithms for alignment of quadrupoles and girders are consid- ered: the algorithm used in the ZDR, the ZDR algorithm combined with a post-alignment MICADO operation, and an algorithm which requires no steering dipoles but requires twice as many alignment segments per linac as the ZDR algorithm. The third algorithm appears to be the most robust, based on convergence time, required quad mover step sizes, and variation in extracted beam emittance as a function of BNS profile. We also study the effect of structure BPM resolution and ATL misalignments during the alignment process. 1 Introduction Beam-based alignment and steering of the

328

Colliding Crystalline Beams  

SciTech Connect

Crystalline Beams* are an ordered state of an ensemble of ions, circulating in a storage ring, with very small velocity fluctuations. They can be obtained from ordinary warm ion beams with the application of powerful cooling techniques (stochastic, electron, laser, ...). Depending on the focussing properties and dimensions of the storage ring, and on the ion beam density, several ground states are possible. All of them can be visualized as a bundle of n{sub s} symmetrically distributed, parallel strings. The longitudinal ion separation {lambda} is the same for all strings. The minimum temperature that can be achieved depends on die background noise of the cooling technique used. It is required for stability that the vibration amplitude of the ions is only a fraction of the separation {lambda}.

Haffmans, A.F.; Maletic, D.; Ruggiero, A.G.

1995-06-01T23:59:59.000Z

329

High-energy accelerator for beams of heavy ions  

DOE Patents (OSTI)

An apparatus for accelerating heavy ions to high energies and directing the accelerated ions at a target comprises a source of singly ionized heavy ions of an element or compound of greater than 100 atomic mass units, means for accelerating the heavy ions, a storage ring for accumulating the accelerated heavy ions and switching means for switching the heavy ions from the storage ring to strike a target substantially simultaneously from a plurality of directions. In a particular embodiment the heavy ion that is accelerated is singly ionized hydrogen iodide. After acceleration, if the beam is of molecular ions, the ions are dissociated to leave an accelerated singly ionized atomic ion in a beam. Extraction of the beam may be accomplished by stripping all the electrons from the atomic ion to switch the beam from the storage ring by bending it in magnetic field of the storage ring.

Martin, Ronald L. (La Grange, IL); Arnold, Richard C. (Chicago, IL)

1978-01-01T23:59:59.000Z

330

Tilting of carbon encapsulated metallic nanocolumns in carbon-nickel nanocomposite films by ion beam assisted deposition  

Science Conference Proceedings (OSTI)

The influence of assisting low-energy ({approx}50-100 eV) ion irradiation effects on the morphology of C:Ni ({approx}15 at. %) nanocomposite films during ion beam assisted deposition (IBAD) is investigated. It is shown that IBAD promotes the columnar growth of carbon encapsulated metallic nanoparticles. The momentum transfer from assisting ions results in tilting of the columns in relation to the growing film surface. Complex secondary structures are obtained, in which a significant part of the columns grows under local epitaxy via the junction of sequentially deposited thin film fractions. The influence of such anisotropic film morphology on the optical properties is highlighted.

Krause, Matthias [Helmholtz-Zentrum Dresden-Rossendorf, PF-510119, 01314 Dresden (Germany); Technische Universitaet Dresden, D-01062 Dresden (Germany); Muecklich, Arndt; Zschornak, Matthias; Wintz, Sebastian; Gemming, Sibylle; Abrasonis, Gintautas [Helmholtz-Zentrum Dresden-Rossendorf, PF-510119, 01314 Dresden (Germany); Oates, Thomas W. H. [Leibniz-Institut fuer Analytische Wissenschaft, ISAS e.V., Albert-Einstein-Str. 9, 12489 Berlin (Germany); Luis Endrino, Jose [Surfaces and Coatings Department, Instituto de Ciencia de Materiales de Madrid, c/Sor Juana Ines de la Cruz 3, Cantoblanco, 28049 Madrid (Spain); Baehtz, Carsten; Shalimov, Artem [Helmholtz-Zentrum Dresden-Rossendorf, PF-510119, 01314 Dresden (Germany); Rossendorf Beamline, European Synchrotron Radiation Facility, F-38043 Grenoble (France)

2012-07-30T23:59:59.000Z

331

BOOSTER GOLD BEAM INJECTION EFFICIENCY AND BEAM LOSS  

SciTech Connect

The Relativistic Heavy Ion Collider (RHIC) at the BNL requires the AGS to provide Gold beam with the intensity of 10{sup 9} ions per bunch. Over the years, the Tandem Van de Graaff has provided steadily increasing intensity of gold ion beams to the AGS Booster. However, the gold beam injection efficiency at the Booster has been found to decrease with the rising intensity of injected beams. As the result, for Tandem beams of the highest intensity, the Booster late intensity is lower than with slightly lower intensity Tandem beam. In this article, the authors present two experiments associated with the Booster injection efficiency and beam intensity. One experiment looks at the Booster injection efficiency by adjusting the Tandem beam intensity, and another looks at the beam life time while scraping the beam in the Booster. The studies suggest that the gold beam injection efficiency at the AGS Booster is related to the beam loss in the ring, rather than the intensity of injected beam or circulating beam. A close look at the effect of the lost gold ion at the Booster injection leads to the prediction that the lost gold ion creates large number of positive ions, and even larger number of electrons. The lost gold beam is also expected to create large numbers of neutral particles. In 1998 heavy ion run, the production of positive ions and electrons due to the lost gold beam has been observed. Also the high vacuum pressure due to the beam loss, presumably because of the neutral particles it created, has been measured. These results will be reported elsewhere.

ZHANG,S.Y.; AHRENS,L.A.

1998-06-22T23:59:59.000Z

332

Beam specie analyzer for intense neutral beams  

DOE Green Energy (OSTI)

A three-channel neutral particle energy analyzer has been fabricated and calibrated for H/sup 0/ particles. H/sup 0/ with energies 3.5-55 keV was passed through a N/sub 2/ gas cell maintained at charge equilibrium pressures. H/sup +/ ions formed by stripping collisions were energy analyzed by a 45/sup 0/, parabolic, electrostatic analyzer and detected by three Faraday cups spaced to intercept the full-, half-, and third-energy beam components. The conversion efficiency of the analyzer system increased from 0.11 at 3.5 keV to 0.54 at 55 keV with an accuracy of +- 3%.

Barnett, C.F.; Ray, J.A.

1981-03-01T23:59:59.000Z

333

Electron beam dynamics for the ISIS bremsstrahlung beam generation system  

E-Print Network (OSTI)

An electron beam transport system was designed for use in the Bremsstrahlung Beam Generation System of the Integrated Stand-off Inspection System (ISIS). The purpose of this electron transport system was to provide for ...

Block, Robert E. (Robert Edward)

2011-01-01T23:59:59.000Z

334

Beam current sensor  

DOE Patents (OSTI)

A current sensor for measuring the dc component of a beam of charged particles employs a superconducting pick-up loop probe, with twisted superconducting leads in combination with a Superconducting Quantum Interference Device (SQUID) detector. The pick-up probe is in the form of a single-turn loop, or a cylindrical toroid, through which the beam is directed and within which a first magnetic flux is excluded by the Meisner effect. The SQUID detector acts as a flux-to-voltage converter in providing a current to the pick-up loop so as to establish a second magnetic flux within the electrode which nulls out the first magnetic flux. A feedback voltage within the SQUID detector represents the beam current of the particles which transit the pick-up loop. Meisner effect currents prevent changes in the magnetic field within the toroidal pick-up loop and produce a current signal independent of the beam's cross-section and its position within the toroid, while the combination of superconducting elements provides current measurement sensitivities in the nano-ampere range.

Kuchnir, M.; Mills, F.E.

1984-09-28T23:59:59.000Z

335

Beam current sensor  

DOE Patents (OSTI)

A current sensor for measuring the DC component of a beam of charged particles employs a superconducting pick-up loop probe, with twisted superconducting leads in combination with a Superconducting Quantum Interference Device (SQUID) detector. The pick-up probe is in the form of a single-turn loop, or a cylindrical toroid, through which the beam is directed and within which a first magnetic flux is excluded by the Meisner effect. The SQUID detector acts as a flux-to-voltage converter in providing a current to the pick-up loop so as to establish a second magnetic flux within the electrode which nulls out the first magnetic flux. A feedback voltage within the SQUID detector represents the beam current of the particles which transit the pick-up loop. Meisner effect currents prevent changes in the magnetic field within the toroidal pick-up loop and produce a current signal independent of the beam's cross-section and its position within the toroid, while the combination of superconducting elements provides current measurement sensitivites in the nano-ampere range.

Kuchnir, Moyses (Elmhurst, IL); Mills, Frederick E. (Elburn, IL)

1987-01-01T23:59:59.000Z

336

Molecular Biology DEGREE PROGRAMME  

E-Print Network (OSTI)

BSc (Hons) Molecular Biology DEGREE PROGRAMME GUIDE 2013-2014 #12;BSc (Hons) Molecular Biology - Year 2 - Year 3 - Year 4 Introduction Molecular biology aims to understand living systems by focusing on the molecular components upon which they are built. Molecular biology is one of great successes of 20th century

Siddharthan, Advaith

337

Positive and Negative Ion Beam Merging System for Neutral Beam ...  

APPLICATIONS OF TECHNOLOGY: Semiconductor manufacturing; Low- and medium-energy ion implantation; Fusion plasma systems requiring neutral beam ...

338

Neutral particle beam intensity controller  

DOE Patents (OSTI)

A neutral beam intensity controller is provided for a neutral beam generator in which a neutral beam is established by accelerating ions from an ion source into a gas neutralizer. An amplitude modulated, rotating magnetic field is applied to the accelerated ion beam in the gas neutralizer to defocus the resultant neutral beam in a controlled manner to achieve intensity control of the neutral beam along the beam axis at constant beam energy. The rotating magnetic field alters the orbits of ions in the gas neutralizer before they are neutralized, thereby controlling the fraction of neutral particles transmitted out of the neutralizer along the central beam axis to a fusion device or the like. The altered path or defocused neutral particles are sprayed onto an actively cooled beam dump disposed perpendicular to the neutral beam axis and having a central open for passage of the focused beam at the central axis of the beamline. Virtually zero therough 100% intensity control is achieved by varying the magnetic field strength without altering the ion source beam intensity or its species yield.

Dagenhart, William K. (Oak Ridge, TN)

1986-01-01T23:59:59.000Z

339

Beam experiments towards high-intensity beams in RHIC  

SciTech Connect

Proton bunch intensities in RHIC are planned to be increased from 2 {center_dot} 10{sup 11} to 3 {center_dot} 10{sup 11} protons per bunch to increase the luminosity, together with head-on beam-beam compensation using electron lenses. To study the feasibility of the intensity increase, beam experiments are being performed. Recent experimental results are presented.

Montag C.; Ahrens, L.; Brennan, J.M.; Blaskiewicz, M.; Drees, A.; Fischer, W.; Hayes, T.; Huang, H.; Mernick, K.; Robert-Demolaize, G.; Smith, K.; Than, R.; Thieberger, P.; Yip, K.; Zeno, K.; Zhang, S.Y.

2012-05-20T23:59:59.000Z

340

JEM Table of Contents: March 1997  

Science Conference Proceedings (OSTI)

266-271] A.T. Ping, A.C. Schmitz, I. Adesida, M. Asif Khan, Q. Chen, and J.W. Yang. In Situ Control of GaN Growth by Molecular Beam Epitaxy [pp. 272-280

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

Archived Selected Headlines of Solid-State Lighting Headlines...  

NLE Websites -- All DOE Office Websites (Extended Search)

molecular beam epitaxy. The research was reported as "A Si-based quantum-dot light-emitting diode" in the March 7, 2005, issue of Applied Physics Letters. News item at...

342

JEM Abstracts: August 1996  

Science Conference Proceedings (OSTI)

A CdHgTe resonant cavity light emitting diode (RCLED) is proposed as a new infrared emitter. The device is prepared by molecular beam epitaxy on a CdZnTe

343

Focused ion beam direct fabrication of micro-optical elements: features compared with laser beam and electron beam direct writing  

E-Print Network (OSTI)

Three types of focused ion beam machine: focused ion beam milling (FIB milling), focused ion beam lithography (FIB lithography), and focused ion beam direct deposition (FIB deposition), are described in detail to compare ...

Fu, Yongqi

344

Dependence of the Photon Beam Characteristics on Electron Beam Parameters in Third Generation Synchrotron Light Sources  

E-Print Network (OSTI)

Dependence of the Photon Beam Characteristics on Electron Beam Parameters in Third Generation Synchrotron Light Sources

Ivanyan, M I; Tsakanov, V M

2002-01-01T23:59:59.000Z

345

Solid-phase epitaxy of silicon amorphized by implantation of the alkali elements rubidium and cesium  

Science Conference Proceedings (OSTI)

The redistribution of implanted Rb and Cs profiles in amorphous silicon during solid-phase epitaxial recrystallization has been investigated by Rutherford backscattering spectroscopy and secondary ion mass spectroscopy. For the implantation dose used in these experiments, the alkali atoms segregate at the a-Si/c-Si interface during annealing resulting in concentration peaks near the interface. In this way, the alkali atoms are moved towards the surface. Rutherford backscattering spectroscopy in ion channeling configuration was performed to measure average recrystallization rates of the amorphous silicon layers. Preliminary studies on the influence of the alkali atoms on the solid-phase epitaxial regrowth rate reveal a strong retardation compared to the intrinsic recrystallization rate.

Maier, R.; Haeublein, V.; Ryssel, H.; Voellm, H.; Feili, D.; Seidel, H.; Frey, L. [Lehrstuhl fuer Elektronische Bauelemente (LEB), Universitaet Erlangen-Nuernberg, Cauerstrasse 6, 91058 Erlangen (Germany); Fraunhofer-Institut fuer Integrierte Systeme und Bauelementetechnologie (IISB), Schottkystrasse 10, 91058 Erlangen (Germany); Lehrstuhl fuer Elektronische Bauelemente (LEB), Universitaet Erlangen-Nuernberg, Cauerstrasse 6, 91058 Erlangen (Germany) and Fraunhofer-Institut fuer Integrierte Systeme und Bauelementetechnologie (IISB), Schottkystrasse 10, 9 (Germany); Lehrstuhl fuer Mikromechanik, Mikrofluidik/ Mikroaktorik (LMM), Universitaet des Saarlandes, Campus A5.1, 66123 Saarbruecken (Germany); Lehrstuhl fuer Elektronische Bauelemente (LEB), Universitaet Erlangen-Nuernberg, Cauerstrasse 6, 91058 Erlangen (Germany) and Fraunhofer-Institut fuer Integrierte Systeme und Bauelementetechnologie (IISB), Schottkystrasse 10,91 (Germany)

2012-11-06T23:59:59.000Z

346

Method utilizing laser-processing for the growth of epitaxial p-n junctions  

DOE Patents (OSTI)

This invention is a new method for the formation of epitaxial p-n junctions in silicon. The method is relatively simple, rapid, and reliable. It produces doped epitaxial layers which are of well-controlled thickness and whose electrical properties are satisfactory. An illustrative form of the method comprises co-depositing a selected dopant and amorphous silicon on a crystalline silicon substrate to form a doped layer of amorphous silicon thereon. This layer then is irradiated with at least one laser pulse to generate a melt front which moves through the layer, into the silicon body to a depth effecting melting of virginal silicon, and back to the surface of the layer. The method may be conducted with dopants (e.g., boron and phosphorus) whose distribution coefficients approximate unity.

Young, R.T.; Narayan, J.; Wood, R.F.

1979-11-23T23:59:59.000Z

347

The Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

PEOPLE JOB OPPORTUNITIES USER'S ASSOCIATION CONTACT US Foundry Intranet DOE Basic Energy Sciences User Facilities Molecular Foundry Seminar "Tuning Phonons in Molecular...

348

NEWTON's Molecular Biology Archive  

NLE Websites -- All DOE Office Websites (Extended Search)

Molecular Biology Archive: Loading Most Recent Molecular Biology Questions: Cytoplasm pH DNA Extract and Cold Alcohol Albino Gene Loci Male Development Candy and Bacteria Revisited...

349

Beam-stack search: Integrating backtracking with beam search  

E-Print Network (OSTI)

We describe a method for transforming beam search into a complete search algorithm that is guaranteed to find an optimal solution. Called beam-stack search, the algorithm uses a new data structure, called a beam stack, that makes it possible to integrate systematic backtracking with beam search. The resulting search algorithm is an anytime algorithm that finds a good, sub-optimal solution quickly, like beam search, and then backtracks and continues to find improved solutions until convergence to an optimal solution. We describe a memory-efficient implementation of beam-stack search, called divide-and-conquer beam-stack search, as well as an iterative-deepening version of the algorithm. The approach is applied to domain-independent STRIPS planning, and computational results show its advantages.

Rong Zhou; Eric A. Hansen

2005-01-01T23:59:59.000Z

350

Laser beam guard clamps  

DOE Patents (OSTI)

A quick insert and release laser beam guard panel clamping apparatus having a base plate mountable on an optical table, a first jaw affixed to the base plate, and a spring-loaded second jaw slidably carried by the base plate to exert a clamping force. The first and second jaws each having a face acutely angled relative to the other face to form a V-shaped, open channel mouth, which enables wedge-action jaw separation by and subsequent clamping of a laser beam guard panel inserted through the open channel mouth. Preferably, the clamping apparatus also includes a support structure having an open slot aperture which is positioned over and parallel with the open channel mouth.

Dickson, Richard K. (Stockton, CA)

2010-09-07T23:59:59.000Z

351

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

1-5 1-5 Nov. 10, 2008 Nov. 11, 2008 Nov. 12, 2008 Nov. 13, 2008 Nov. 14, 2008 Nov. 15, 2008 Nov. 16, 2008 DOWN FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI BEAM LINE 7-1 Nov. 10, 2008 Nov. 11, 2008 Nov. 12, 2008 Nov. 13, 2008 Nov. 14, 2008 Nov. 15, 2008 Nov. 16, 2008 DOWN FACI FACI FACI FACI FACI FACI

352

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

1-5 1-5 Nov. 05, 2007 Nov. 06, 2007 Nov. 07, 2007 Nov. 08, 2007 Nov. 09, 2007 Nov. 10, 2007 Nov. 11, 2007 Unscheduled FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI BEAM LINE 7-1 Nov. 05, 2007 Nov. 06, 2007 Nov. 07, 2007 Nov. 08, 2007 Nov. 09, 2007 Nov. 10, 2007 Nov. 11, 2007 Unscheduled FACI FACI FACI FACI FACI FACI

353

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

4 4 Mar. 15, 2004 Mar. 16, 2004 Mar. 17, 2004 Mar. 18, 2004 Mar. 19, 2004 Mar. 20, 2004 Mar. 21, 2004 DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN BEAM LINE 1-5 Mar. 15, 2004 Mar. 16, 2004 Mar. 17, 2004 Mar. 18, 2004 Mar. 19, 2004 Mar. 20, 2004 Mar. 21, 2004 DOWN DOWN DOWN DOWN DOWN DOWN DOWN

354

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

5-1 5-1 Nov. 28, 2005 Nov. 29, 2005 Nov. 30, 2005 Dec. 01, 2005 Dec. 02, 2005 Dec. 03, 2005 Dec. 04, 2005 MA FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI FACI BEAM LINE 5-2 Nov. 28, 2005 Nov. 29, 2005 Nov. 30, 2005 Dec. 01, 2005 Dec. 02, 2005 Dec. 03, 2005 Dec. 04, 2005 MA FACI FACI FACI FACI FACI FACI

355

Ion beam generating apparatus  

DOE Patents (OSTI)

An ion generating apparatus utilizing a vacuum chamber, a cathode and an anode in the chamber. A source of electrical power produces an arc or discharge between the cathode and anode. The arc is sufficient to vaporize a portion of the cathode to form a plasma. The plasma is directed to an extractor which separates the electrons from the plasma, and accelerates the ions to produce an ion beam.

Brown, Ian G. (1088 Woodside Rd., Berkeley, CA 94708); Galvin, James (2 Commodore #276, Emeryville, CA 94608)

1987-01-01T23:59:59.000Z

356

Ion beam generating apparatus  

DOE Patents (OSTI)

An ion generating apparatus utilizing a vacuum chamber, a cathode and an anode in the chamber. A source of electrical power produces an arc or discharge between the cathode and anode. The arc is sufficient to vaporize a portion of the cathode to form a plasma. The plasma is directed to an extractor which separates the electrons from the plasma, and accelerates the ions to produce an ion beam. 10 figs.

Brown, I.G.; Galvin, J.

1987-12-22T23:59:59.000Z

357

Relativistic electron beam device  

DOE Patents (OSTI)

A design is given for an electron beam device for irradiating spherical hydrogen isotope bearing targets. The accelerator, which includes hollow cathodes facing each other, injects an anode plasma between the cathodes and produces an approximately 10 nanosecond, megajoule pulse between the anode plasma and the cathodes. Targets may be repetitively positioned within the plasma between the cathodes, and accelerator diode arrangement permits materials to survive operation in a fusion power source. (auth)

Freeman, J.R.; Poukey, J.W.; Shope, S.L.; Yonas, G.

1975-07-01T23:59:59.000Z

358

Stationary nonlinear Airy beams  

Science Conference Proceedings (OSTI)

We demonstrate the existence of an additional class of stationary accelerating Airy wave forms that exist in the presence of third-order (Kerr) nonlinearity and nonlinear losses. Numerical simulations and experiments, in agreement with the analytical model, highlight how these stationary solutions sustain the nonlinear evolution of Airy beams. The generic nature of the Airy solution allows extension of these results to other settings, and a variety of applications are suggested.

Lotti, A. [Dipartimento di Fisica e Matematica, Universita del'Insubria, Via Valleggio 11, I-22100 Como (Italy); Centre de Physique Theorique, CNRS, Ecole Polytechnique, F-91128 Palaiseau (France); Faccio, D. [Dipartimento di Fisica e Matematica, Universita del'Insubria, Via Valleggio 11, I-22100 Como (Italy); School of Engineering and Physical Sciences, SUPA, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Couairon, A. [Centre de Physique Theorique, CNRS, Ecole Polytechnique, F-91128 Palaiseau (France); Papazoglou, D. G. [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology, Hellas (FORTH), P.O. Box 1527, GR-71110 Heraklion (Greece); Materials Science and Technology Department, University of Crete, GR-71003 Heraklion (Greece); Panagiotopoulos, P.; Tzortzakis, S. [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology, Hellas (FORTH), P.O. Box 1527, GR-71110 Heraklion (Greece); Abdollahpour, D. [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology, Hellas (FORTH), P.O. Box 1527, GR-71110 Heraklion (Greece); Physics Department, University of Crete, GR-71003 Heraklion (Greece)

2011-08-15T23:59:59.000Z

359

Epitaxial europium oxide on Ni(100) with single-crystal quality  

SciTech Connect

High quality epitaxy of EuO on Ni(100) is developed in an in situ scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) study. A careful selection of the initial growth parameters is decisive to obtain a surface oxide suitable for the subsequent epitaxy of single phase EuO(100). After the creation of a three layer thick coalesced oxide film for the subsequent growth a distillation technique is applied. Appropriate annealing of films with up to 100 nm thickness generates sufficient conductivity for STM and electron spectroscopies. Oxygen vacancies are directly imaged by STM. They are of decisive importance for the metal-to-insulator transition around the temperature of the ferromagnetic-to-paramagnetic transition. A fast relaxation of the initial biaxial strain observed by LEED leaves little hope for an increase of the Curie temperature through epitaxial compression. Ex situ x-ray adsorption spectroscopy and magneto-optical Kerr effect microscopy measurements of thicker films are consistent with the stoichiometric single phase EuO with bulk properties.

Foerster, Daniel F.; Klinkhammer, Juergen; Busse, Carsten; Altendorf, Simone G.; Michely, Thomas; Hu Zhiwei; Chin Yiying; Tjeng, L. H.; Coraux, Johann; Bourgault, Daniel [II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln (Germany); II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln, Germany and Max Planck Institute for Chemical Physics of Solids, Noethnitzerstr. 40, D-01187 Dresden (Germany); Institut Neel, CNRS-UJF, 25 rue des Martyrs, F-38042 Grenoble Cedex 9 (France)

2011-01-15T23:59:59.000Z

360

Biaxial texturing of inorganic photovoltaic thin films using low energy ion beam irradiation during growth  

SciTech Connect

We describe our efforts to control the grain boundary alignment in polycrystalline thin films of silicon by using a biaxially textured template layer of CaF{sub 2} for photovoltaic device applications. We have chosen CaF{sub 2} as a candidate material due to its close lattice match with silicon and its suitability as an ion beam assisted deposition (mAD) material. We show that the CaF{sub 2} aligns biaxially at a thickness of {approx}10 nm and, with the addition of an epitaxial CaF{sub 2} layer, has an in-plane texture of {approx}15{sup o}. Deposition of a subsequent layer of Si aligns on the template layer with an in-plane texture of 10.8{sup o}. The additional improvement of in-plane texture is similar to the behavior observed in more fully characterized IBAD materials systems. A germanium buffer layer is used to assist in the epitaxial deposition of Si on CaF{sub 2} template layers and single crystal substrates. These experiments confirm that an mAD template can be used to biaxially orient polycrystalline Si.

Groves, Jaes R [Los Alamos National Laboratory; De Paula, Raymond F [Los Alamos National Laboratory; Hayes, Garrett H [STANFORD UNIV.; Li, Joel B [STANFORD UNIV.; Hammond, Robert H [STANFORD UNIV.; Salleo, Alberto [STANFORD UNIV.; Clemens, Bruce M [STANFORD UNIV.

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

Beam-Beam Interaction Simulations with Guinea Pig  

NLE Websites -- All DOE Office Websites (Extended Search)

5 5 SLAC-TN-03-070 September 2003 Beam-Beam Interaction Simulations with Guinea Pig C. Sramek, T. O. Raubenheimer, A. Seryi, M. Woods, J. Yu Stanford Linear Accelerator Center Stanford University Stanford, CA Abstract: At the interaction point of a particle accelerator, various phenomena occur that are known as beam-beam effects. Incident bunches of electrons (or positrons) experience strong electromagnetic fields from the opposing bunches, which leads to electron deflection, beamstrahlung and the creation of electron/positron pairs and hadrons due to two-photon exchange. In addition, the beams experience a "pinch effect" which focuses each beam and results in either a reduction or expansion of their vertical size. Finally, if a

362

BEAM HALO FORMATION IN HIGH-INTENSITY BEAMS.  

SciTech Connect

Studies of beam halo became unavoidable feature of high-intensity machines where uncontrolled beam loss should be kept to extremely small level. For a well controlled stable beam such a loss is typically associated with the low density halo surrounding beam core. In order to minimize uncontrolled beam loss or improve performance of an accelerator, it is very important to understand what are the sources of halo formation in a specific machine of interest. The dominant mechanisms are, in fact, different in linear accelerators, circular machines or Energy Recovering Linacs (ERL). In this paper, we summarize basic mechanisms of halo formation in high-intensity beams and discuss their application to various types of accelerators of interest, such as linacs, rings and ERL.

FEDOTOV, A.V.

2005-03-18T23:59:59.000Z

363

A low energy beam transport system for proton beam  

SciTech Connect

A low energy beam transport (LEBT) system has been built for a compact pulsed hadron source (CPHS) at Tsinghua University in China. The LEBT, consisting of two solenoids and three short-drift sections, transports a pulsed proton beam of 60 mA of energy of 50 keV to the entrance of a radio frequency quadrupole (RFQ). Measurement has shown a normalized RMS beam emittance less than 0.2 {pi} mm mrad at the end of the LEBT. Beam simulations were carried out to compare with the measurement and are in good agreement. Based on the successful CPHS LEBT development, a new LEBT for a China ADS projector has been designed. The features of the new design, including a beam chopper and beam simulations of the LEBT are presented and discussed along with CPHS LEBT development in this article.

Yang, Y. [Institute of Modern Physics, CAS, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Zhang, Z. M.; Wu, Q.; Zhang, W. H.; Ma, H. Y.; Sun, L. T.; Zhang, X. Z.; Liu, Z. W.; He, Y.; Zhao, H. W.; Xie, D. Z. [Institute of Modern Physics, CAS, Lanzhou 730000 (China)

2013-03-15T23:59:59.000Z

364

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

5 5 Mar. 15, 2004 Mar. 16, 2004 Mar. 17, 2004 Mar. 18, 2004 Mar. 19, 2004 Mar. 20, 2004 Mar. 21, 2004 DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN DOWN BEAM LINE 9-1 Mar. 15, 2004 Mar. 16, 2004 Mar. 17, 2004 Mar. 18, 2004 Mar. 19, 2004 Mar. 20, 2004 Mar. 21, 2004 Unscheduled CHANGE/8837 A.COHE 8837 A.COHEN 8837 A.COHEN 8837 A.COHEN 8837 A.COHEN 8837 A.COHEN

365

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

1-4 1-4 Oct. 30, 2006 Oct. 31, 2006 Nov. 01, 2006 Nov. 02, 2006 Nov. 03, 2006 Nov. 04, 2006 Nov. 05, 2006 DOWN Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled BEAM LINE 2-1 Oct. 30, 2006 Oct. 31, 2006 Nov. 01, 2006 Nov. 02, 2006 Nov. 03, 2006 Nov. 04, 2006 Nov. 05, 2006 DOWN 8859 B.JOHNSON 8859 B.JOHNSON 8859 B.JOHNSON 8859 B.JOHNSON 8859 B.JOHNSON 8859 B.JOHNSON

366

Precision Absolute Beam Current Measurement of Low Power Electron Beam  

SciTech Connect

Precise measurements of low power CW electron beam current for the Jefferson Lab Nuclear Physics program have been performed using a Tungsten calorimeter. This paper describes the rationale for the choice of the calorimeter technique, as well as the design and calibration of the device. The calorimeter is in use presently to provide a 1% absolute current measurement of CW electron beam with 50 to 500 nA of average beam current and 1-3 GeV beam energy. Results from these recent measurements will also be presented.

Ali, M. M.; Bevins, M. E.; Degtiarenko, P.; Freyberger, A.; Krafft, G. A.

2012-11-01T23:59:59.000Z

367

Magnetically operated beam dump for dumping high power beams in a neutral beamline  

DOE Patents (OSTI)

It is an object of this invention to provide a beam dump system for a neutral beam generator which lowers the time-averaged power density of the beam dump impingement surface. Another object of this invention is to provide a beam dump system for a neutral particle beam based on reionization and subsequent magnetic beam position modulation of the beam onto a beam dump surface to lower the time-averaged power density of the beam dump ion impingement surface.

Dagenhart, W.K.

1984-01-27T23:59:59.000Z

368

LANL: Ion Beam Materials Laboratory  

NLE Websites -- All DOE Office Websites (Extended Search)

Ion Beam Materials Laboratory (IBML) is a Los Ion Beam Materials Laboratory (IBML) is a Los Alamos National Laboratory resource devoted to materi- als research through the use of ion beams. Current major research areas include surface characterization through ion beam analysis techniques, surface modification and materials synthesis through ion implantation technology, and radiation damage stud- ies in gases, liquids, and solids. The laboratory's core is a 3.2 MV tandem ion accelerator and a 200 kV ion implanter together with several beam lines. Attached to each beam line is a series of experimental stations that support various research programs. The operation of IBML and its interactions with users are organized around core facilities and experimental stations. The IBML provides and operates the core facilities as well as supports

369

Beam-line cryopump  

DOE Green Energy (OSTI)

A cryopumping module using metallic surfaces at liquid helium temperature for condensation of hydrogen and deuterium gas has been constructed. This pump, a prototype of four units which will provide pumping for the Livermore 200 kV test stand, will be used to verify the concept and establish engineering parameters. Upon completion of engineering tests and evaluation the pump will be installed in an operating beam line. The design point pumping capacity is 80,000 liters per second for hydrogen and deuterium at 10$sup -4$ torr based on sticking coefficients of 0.15 and 0.25, respectively. Both the liquid helium temperature pumping surface and the liquid nitrogen temperature radiation shields are constructed of quilted double wall cylindrical shells. The pumping shell dimensions are 1.5 meters dia. x 0.6 meters long. Cryogen circulation is convection current driven in both cases. Liquid helium is supplied from an overhead Dewar through bayonet coupling. In the 200 kV beam line, pumping modules will be supplied via transfer lines from a central Dewar. Voltage standoff will be accomplished in the transfer lines. (auth)

Duffy, T.J.; Oddon, L.D.

1975-11-12T23:59:59.000Z

370

Beam emittance measurements at Fermilab  

Science Conference Proceedings (OSTI)

We give short overview of various beam emittance measurement methods, currently applied at different machine locations for the Run II collider physics program at Fermilab. All these methods are based on beam profile measurements, and we give some examples of the related instrumentation techniques. At the end we introduce a multi-megawatt proton source project, currently under investigation at Fermilab, with respect to the beam instrumentation challenges.

Wendt, Manfred; Eddy, Nathan; Hu, Martin; Scarpine, Victor; Syphers, Mike; Tassotto, Gianni; Thurman-Keup, Randy; Yang, Ming-Jen; Zagel, James; /Fermilab

2008-01-01T23:59:59.000Z

371

A pencil beam algorithm for helium ion beam therapy  

Science Conference Proceedings (OSTI)

Purpose: To develop a flexible pencil beam algorithm for helium ion beam therapy. Dose distributions were calculated using the newly developed pencil beam algorithm and validated using Monte Carlo (MC) methods. Methods: The algorithm was based on the established theory of fluence weighted elemental pencil beam (PB) kernels. Using a new real-time splitting approach, a minimization routine selects the optimal shape for each sub-beam. Dose depositions along the beam path were determined using a look-up table (LUT). Data for LUT generation were derived from MC simulations in water using GATE 6.1. For materials other than water, dose depositions were calculated by the algorithm using water-equivalent depth scaling. Lateral beam spreading caused by multiple scattering has been accounted for by implementing a non-local scattering formula developed by Gottschalk. A new nuclear correction was modelled using a Voigt function and implemented by a LUT approach. Validation simulations have been performed using a phantom filled with homogeneous materials or heterogeneous slabs of up to 3 cm. The beams were incident perpendicular to the phantoms surface with initial particle energies ranging from 50 to 250 MeV/A with a total number of 10{sup 7} ions per beam. For comparison a special evaluation software was developed calculating the gamma indices for dose distributions. Results: In homogeneous phantoms, maximum range deviations between PB and MC of less than 1.1% and differences in the width of the distal energy falloff of the Bragg-Peak from 80% to 20% of less than 0.1 mm were found. Heterogeneous phantoms using layered slabs satisfied a {gamma}-index criterion of 2%/2mm of the local value except for some single voxels. For more complex phantoms using laterally arranged bone-air slabs, the {gamma}-index criterion was exceeded in some areas giving a maximum {gamma}-index of 1.75 and 4.9% of the voxels showed {gamma}-index values larger than one. The calculation precision of the presented algorithm was considered to be sufficient for clinical practice. Although only data for helium beams was presented, the performance of the pencil beam algorithm for proton beams was comparable. Conclusions: The pencil beam algorithm developed for helium ions presents a suitable tool for dose calculations. Its calculation speed was evaluated to be similar to other published pencil beam algorithms. The flexible design allows easy customization of measured depth-dose distributions and use of varying beam profiles, thus making it a promising candidate for integration into future treatment planning systems. Current work in progress deals with RBE effects of helium ions to complete the model.

Fuchs, Hermann; Stroebele, Julia; Schreiner, Thomas; Hirtl, Albert; Georg, Dietmar [Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, 1090 Vienna (Austria); Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria) and Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria); Department of Radiation Oncology, Medical University of Vienna/AKH Vienna (Austria) and Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria); PEG MedAustron, 2700 Wiener Neustadt (Austria); Department of Nuclear Medicine, Medical University of Vienna, 1090 Vienna (Austria); Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, 1090 Vienna (Austria); Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria) and Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria)

2012-11-15T23:59:59.000Z

372

Broad-band beam buncher  

DOE Patents (OSTI)

A broad-band beam buncher is disclosed, comprising an evacuated housing, an electron gun therein for producing an electron beam, a buncher cavity having entrance and exit openings through which the beam is directed, grids across such openings, a source providing a positive DC voltage between the cavity and the electron gun, a drift tube through which the electron beam travels in passing through such cavity, grids across the ends of such drift tube, gaps being provided between the drift tube grids and the entrance and exit grids, a modulator for supplying an ultrahigh frequency modulating signal to the drift tube for producing velocity modulation of the electrons in the beam, a drift space in the housing through which the velocity modulated electron beam travels and in which the beam is bunched, and a discharge opening from such drift tube and having a grid across such opening through which the bunched electron beam is discharged into an accelerator or the like. The buncher cavity and the drift tube may be arranged to constitute an extension of a coaxial transmission line which is employed to deliver the modulating signal from a signal source. The extended transmission line may be terminated in its characteristic impedance to afford a broad-band response and the device as a whole designed to effect broad-band beam coupling, so as to minimize variations of the output across the response band.

Goldberg, David A. (Walnut Creek, CA); Flood, William S. (Berkeley, CA); Arthur, Allan A. (Martinez, CA); Voelker, Ferdinand (Orinda, CA)

1986-01-01T23:59:59.000Z

373

Electron Beam Melting (EBM) II  

Science Conference Proceedings (OSTI)

Oct 19, 2011 ... Additive Manufacturing of Metals: Electron Beam Melting (EBM) II Sponsored by: MS&T Organization Program Organizers: Ian D. Harris, EWI;...

374

Transmission Electron Microscopy Study of Nonpolar a-Plane GaN Grown by Pendeo-Epitaxy on (112_0) 4H-SiC  

E-Print Network (OSTI)

by Pendeo-Epitaxy on (1120) 4H-SiC. D.N. Zakharov 1 , Z.phase epitaxy on (1120) 4H-SiC substrates with AlN bufferPE layers were grown on 4H- SiC (1120) substrates previously

Zakharov, D.N.; Liliental-Weber, Z.; Wagner, B.; Reitmeier, Z.J.; Preble, E.A.; Davis, R.F.

2008-01-01T23:59:59.000Z

375

C-V characteristics of epitaxial germanium metal-oxide-semiconductor capacitor on GaAs substrate with ALD Al2O3 dielectric  

Science Conference Proceedings (OSTI)

Epitaxial germanium metal-oxide-semiconductor capacitors (MOSCAP) were fabricated on GaAs substrate using atomic layer deposited Al"2O"3 gate dielectric with surface treatments including pure HF and HF plus rapid thermal oxidation (RTO). The electrical ... Keywords: ALD Al2O3, CMOS integration, Ge MOSCAP, Ge epitaxial film, RTO

Shih Hsuan Tang; Chien I. Kuo; Hai Dang Trinh; Mantu Hudait; Edward Yi Chang; Ching Yi Hsu; Yung Hsuan Su; Guang-Li Luo; Hong Quan Nguyen

2012-09-01T23:59:59.000Z

376

Abstract--Selective epitaxial growth of crystalline Ge on Si in a standard ASM Epsilon 2000 CVD reactor is investigated for the  

E-Print Network (OSTI)

In a standard CVD reactor, Ge selective epitaxial growth on patterned Si substrates was developed in thickness. The epitaxy is performed in a standard ASM Epsilon 2000 chemical-vapor-deposition (CVD) reactor surface after Ge-growth make this an attractive and straightforward add-on to standard Si technology. #12

Technische Universiteit Delft

377

Accelerators, Beams And Physical Review Special Topics - Accelerators And Beams  

SciTech Connect

Accelerator science and technology have evolved as accelerators became larger and important to a broad range of science. Physical Review Special Topics - Accelerators and Beams was established to serve the accelerator community as a timely, widely circulated, international journal covering the full breadth of accelerators and beams. The history of the journal and the innovations associated with it are reviewed.

Siemann, R.H.; /SLAC

2011-10-24T23:59:59.000Z

378

NEUTRAL-BEAM INJECTION  

SciTech Connect

The emphasis in the preceding chapters has been on magnetic confinement of high temperature plasmas. The question of production and heating of such plasmas has been dealt with relatively more briefly. It should not be inferred, however, that these matters must therefore be either trivial or unimportant. A review of the history reveals that in the early days all these aspects of the controlled fusion problem were considered to be on a par, and were tackled simultaneously and with equal vigor. Only the confinement problem turned out to be much more complex than initially anticipated, and richer in challenge to the plasma physicist than the questions of plasma production and heating. On the other hand, the properties of high-temperature plasmas and plasma confinement can only be studied experimentally after the problems of production and of heating to adequate temperatures are solved. It is the purpose of this and the next chapter to supplement the preceding discussions with more detail on two important subjects: neutral-beam injection and radio-frequency heating. These are the major contenders for heating in present and future tokamak and mirror fusion experiments, and even in several proposed reactors. For neutral beams we emphasize here the technology involved, which has undergone a rather remarkable development. The physics of particle and energy deposition in the plasma, and the discussion of the resulting effects on the confined plasma, have been included in previous chapters, and some experimental results are quoted there. Other heating processes of relevance to fusion are mentioned elsewhere in this book, in connection with the experiments where they are used: i.e. ohmic heating, adiabatic compression heating, and alpha-particle heating in Chapter 3 by H.P. Furth; more ohmic heating in Chapter 7, and shock-implosion heating, laser heating, and relativistic-electron beam heating in Chapter 8, both by W. E. Quinn. These methods are relatively straightforward in their physics and their technology, or in any case they are considered to be adequately covered by these other authors.

Kunkel, W.B.

1980-06-01T23:59:59.000Z

379

Heavy Oil Upgrading from Electron Beam (E-Beam) Irradiation  

E-Print Network (OSTI)

Society's growing demands for energy results in rapid increase in oil consumption and motivates us to make unconventional resources conventional resources. There are enormous amounts of heavy oil reserves in the world but the lack of cost effective technologies either for extraction, transportation, or refinery upgrading hinders the development of heavy oil reserves. One of the critical problems with heavy oil and bitumen is that they require large amounts of thermal energy and expensive catalysts to upgrade. This thesis demonstrates that electron beam (E-Beam) heavy oil upgrading, which uses unique features of E-Beam irradiation, may be used to improve conventional heavy oil upgrading. E-Beam processing lowers the thermal energy requirements and could sharply reduce the investment in catalysts. The design of the facilities can be simpler and will contribute to lowering the costs of transporting and processing heavy oil and bitumen. E-Beam technology uses the high kinetic energy of fast electrons, which not only transfer their energy but also interact with hydrocarbons to break the heavy molecules with lower thermal energy. In this work, we conducted three major stages to evaluate the applicability of E-Beam for heavy oil upgrading. First, we conducted laboratory experiments to investigate the effects of E-Beam on hydrocarbons. To do so, we used a Van de Graff accelerator, which generates the high kinetic energy of electrons, and a laboratory scale apparatus to investigate extensively how radiation effects hydrocarbons. Second, we studied the energy transfer mechanism of E-Beam upgrading to optimize the process. Third, we conducted a preliminary economic analysis based on energy consumption and compared the economics of E-Beam upgrading with conventional upgrading. The results of our study are very encouraging. From the experiments we found that E-Beam effect on hydrocarbon is significant. We used less thermal energy for distillation of n-hexadecane (n-C16) and naphtha with E-Beam. The results of experiments with asphaltene indicate that E-Beam enhances the decomposition of heavy hydrocarbon molecules and improves the quality of upgraded hydrocarbon. From the study of energy transfer mechanism, we estimated heat loss, fluid movement, and radiation energy distribution during the reaction. The results of our economic evaluation show that E-Beam upgrading appears to be economically feasible in petroleum industry applications. These results indicate significant potential for the application of E-Beam technology throughout the petroleum industry, particularly near production facilities, transportation pipelines, and refining industry.

Yang, Daegil

2009-12-01T23:59:59.000Z

380

Anomalous acid diffusion in a triphenylene molecular resist with melamine crosslinker  

Science Conference Proceedings (OSTI)

Next generation lithography will require next generation resists. Molecular resists, based on small non-polymeric molecules, promise improvements in line width roughness and resolution control for high resolution lithographic patterns. However, these ... Keywords: Chemical amplification, Electron beam resist, Lithography, Melamine, Molecular resist, Photoacid diffusion, Triphenylene

H. M. Zaid; M. Manickam; J. A. Preece; R. E. Palmer; A. P. G. Robinson

2008-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

Tuning the beam: a physics perspective on beam diagnostic instrumentation  

SciTech Connect

In a nutshell, the role of a beam diagnostic measurement is to provide information needed to get a particle beam from Point A (injection point) to Point B (a target) in a useable condition, with 'useable' meaning the right energy and size and with acceptable losses. Specifications and performance requirements of diagnostics are based on the physics of the particle beam to be measured, with typical customers of beam parameter measurements being the accelerator operators and accelerator physicists. This tutorial will be a physics-oriented discussion of the interplay between tuning evolutions and the beam diagnostics systems that support the machine tune. This will include the differences between developing a tune and maintaining a tune, among other things. Practical longitudinal and transverse tuning issues and techniques from a variety of proton and electron machines will also be discussed.

Gulley, Mark S [Los Alamos National Laboratory

2010-01-01T23:59:59.000Z

382

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

5-4 5-4 Nov. 05, 2007 Nov. 06, 2007 Nov. 07, 2007 Nov. 08, 2007 Nov. 09, 2007 Nov. 10, 2007 Nov. 11, 2007 Unscheduled 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU CHANGE/8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU BEAM LINE 8-1 Nov. 05, 2007 Nov. 06, 2007 Nov. 07, 2007 Nov. 08, 2007 Nov. 09, 2007 Nov. 10, 2007 Nov. 11, 2007 8821 D.Brehmer 8821 D.Brehmer 8821 D.Brehmer 3064* S.SUN 3075 M.GARNER 3075 M.GARNER 3075 M.GARNER

383

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

4, 2013 Nov. 11, 2013 Nov. 18, 2013 Nov. 25, 2013 4, 2013 Nov. 11, 2013 Nov. 18, 2013 Nov. 25, 2013 Dec. 02, 2013 Dec. 09, 2013 Dec. 16, 2013 Dec. 23, 2013 Dec. 30, 2013 Jan. 06, 2014 Jan. 13, 2014 Jan. 20, 2014 Jan. 27, 2014 Feb. 03, 2014 Back to Table of Contents WEEK OF Nov. 04, 2013 Ops Re-start Nov. 04, 2013 Nov. 05, 2013 Nov. 06, 2013 Nov. 07, 2013 Nov. 08, 2013 Nov. 09, 2013 Nov. 10, 2013 BEAM LINE 5-4 Nov. 04, 2013 Nov. 05, 2013 Nov. 06, 2013 Nov. 07, 2013 Nov. 08, 2013 Nov. 09, 2013 Nov. 10, 2013 DOWN DOWN DOWN DOWN DOWN DOWN DOWN

384

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

1-4 1-4 Nov. 28, 2005 Nov. 29, 2005 Nov. 30, 2005 Dec. 01, 2005 Dec. 02, 2005 Dec. 03, 2005 Dec. 04, 2005 MA 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE CHANGE/8840 J.POPL 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE 8840 J.POPLE BEAM LINE 2-1 Nov. 28, 2005 Nov. 29, 2005 Nov. 30, 2005 Dec. 01, 2005 Dec. 02, 2005 Dec. 03, 2005 Dec. 04, 2005 MA 8859 B.JOHNSON 8859 B.JOHNSON 8859 B.JOHNSON 8859 B.JOHNSON 8859 B.JOHNSON 8859 B.JOHNSON

385

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

5-4 5-4 Nov. 15, 2010 Nov. 16, 2010 Nov. 17, 2010 Nov. 18, 2010 Nov. 19, 2010 Nov. 20, 2010 Nov. 21, 2010 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU 8820 D.LU BEAM LINE 8-1 Nov. 15, 2010 Nov. 16, 2010 Nov. 17, 2010 Nov. 18, 2010 Nov. 19, 2010 Nov. 20, 2010 Nov. 21, 2010 Unscheduled Unscheduled Unscheduled 3269 S.SUN 3269 S.SUN 3269 S.SUN 3269 S.SUN

386

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

1, 2002 Nov. 18, 2002 Nov. 25, 2002 Dec. 02, 2002 1, 2002 Nov. 18, 2002 Nov. 25, 2002 Dec. 02, 2002 Dec. 09, 2002 Dec. 16, 2002 Dec. 23, 2002 Dec. 30, 2002 Jan. 06, 2003 Jan. 13, 2003 Jan. 20, 2003 Jan. 27, 2003 Feb. 03, 2003 Feb. 10, 2003 Feb. 17, 2003 Feb. 24, 2003 Mar. 03, 2003 Mar. 10, 2003 Mar. 17, 2003 Mar. 24, 2003 Mar. 31, 2003 Back to Table of Contents WEEK OF Nov. 11, 2002 Nov. 11, 2002 Nov. 12, 2002 Nov. 13, 2002 Nov. 14, 2002 Nov. 15, 2002 Nov. 16, 2002 Nov. 17, 2002 BEAM LINE 1-4 Nov. 11, 2002 Nov. 12, 2002 Nov. 13, 2002 Nov. 14, 2002 Nov. 15, 2002 Nov. 16, 2002 Nov. 17, 2002 Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled Unscheduled

387

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

Nov. 04, 2013 Nov. 11, 2013 Nov. 18, 2013 Nov. 25, 2013 Nov. 04, 2013 Nov. 11, 2013 Nov. 18, 2013 Nov. 25, 2013 Dec. 02, 2013 Dec. 09, 2013 Dec. 16, 2013 Dec. 23, 2013 Dec. 30, 2013 Jan. 06, 2014 Jan. 13, 2014 Jan. 20, 2014 Jan. 27, 2014 Feb. 03, 2014 Back to Table of Contents WEEK OF Nov. 04, 2013 Ops Re-start Nov. 04, 2013 Nov. 05, 2013 Nov. 06, 2013 Nov. 07, 2013 Nov. 08, 2013 Nov. 09, 2013 Nov. 10, 2013 BEAM LINE 1-4 Nov. 04, 2013 Nov. 05, 2013 Nov. 06, 2013 Nov. 07, 2013 Nov. 08, 2013 Nov. 09, 2013 Nov. 10, 2013 DOWN DOWN DOWN 8891 C.TASSONE 8891 C.TASSONE 8891 C.TASSONE 8891 C.TASSONE

388

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

1-4 1-4 Nov. 05, 2007 Nov. 06, 2007 Nov. 07, 2007 Nov. 08, 2007 Nov. 09, 2007 Nov. 10, 2007 Nov. 11, 2007 Unscheduled Unscheduled 8051 M.TONEY 8051 M.TONEY 8051 M.TONEY 8051 M.TONEY 8051 M.TONEY Unscheduled CHANGE/8051 M.TONE 8051 M.TONEY 8051 M.TONEY 8051 M.TONEY 8051 M.TONEY 8051 M.TONEY Unscheduled 8051 M.TONEY 8051 M.TONEY 8051 M.TONEY 8051 M.TONEY 8051 M.TONEY 8051 M.TONEY BEAM LINE 2-1 Nov. 05, 2007 Nov. 06, 2007 Nov. 07, 2007 Nov. 08, 2007 Nov. 09, 2007 Nov. 10, 2007 Nov. 11, 2007 8859 B.JOHNSON 8859 B.JOHNSON 8859 B.JOHNSON 8859 B.JOHNSON 3157* M.MONTERO-CA 3087 L.FUENTES-COB 3087 L.FUENTES-COB

389

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

1-5 1-5 Nov. 28, 2005 Nov. 29, 2005 Nov. 30, 2005 Dec. 01, 2005 Dec. 02, 2005 Dec. 03, 2005 Dec. 04, 2005 MA 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ BEAM LINE 7-1 Nov. 28, 2005 Nov. 29, 2005 Nov. 30, 2005 Dec. 01, 2005 Dec. 02, 2005 Dec. 03, 2005 Dec. 04, 2005 MA DOWN DOWN DOWN DOWN DOWN DOWN

390

Pulsed electron beam precharger  

Science Conference Proceedings (OSTI)

Florida State University is investigating the concept of pulsed electron beams for fly ash precipitation. This report describes the results and data on three of the subtasks of this project and preliminary work only on the remaining five subtasks. Described are the modification of precharger for pulsed and DC energization of anode; installation of the Q/A measurement system; and modification and installation of pulsed power supply to provide both pulsed and DC energization of the anode. The other tasks include: measurement of the removal efficiency for monodisperse simulated fly ash particles; measurement of particle charge; optimization of pulse energization schedule for maximum removal efficiency; practical assessment of results; and measurement of the removal efficiency for polydisperse test particles. 15 figs., 1 tab. (CK)

Finney, W.C. (ed.); Shelton, W.N.

1990-01-01T23:59:59.000Z

391

Continuous spin reorientation transition in epitaxially grown antiferromagnetic NiO thin films  

SciTech Connect

Fe/NiO/MgO/Ag(001) films were grown epitaxially, and the Fe and NiO spin orientations were determined using x-ray magnetic dichroism. We find that the NiO spins are aligned perpendicularly to the in-plane Fe spins. Analyzing both the in-plane and out-of-plane spin components of the NiO layer, we demonstrate unambiguously that the antiferromagnetic NiO spins undergo a continuous spin reorientation transition from the in-plane to out-of-plane directions with increasing of the MgO thickness.

Li, J.; Arenholz, E.; Meng, Y.; Tan, A.; Park, J.; Jin, E.; Son, H.; Wu, J.; Jenkins, C. A.; Scholl, A.; Hwang, Chanyong; Qiu, Z. Q.

2011-03-01T23:59:59.000Z

392

Polariton Enhanced IR Reflection Spectra of Epitaxial Graphene on SiC  

E-Print Network (OSTI)

We show ~10x polariton-enhanced infrared reflectivity of epitaxial graphene on 4H-SiC, in SiC's restrahlen band (8-10um). By fitting measurements to theory, we extract the thickness, N, in monolayers (ML), momentum scattering time, Fermi level position of graphene and estimate carrier mobility. By showing that 1/root(ns), the carrier concentration/ML, we argue that scattering is dominated by short-range interactions at the SiC/graphene interface. Polariton formation finds application in near-field optical devices such as superlenses.

Daas, B K; Sudarshan, T S; Chandrashekhar, M V S

2010-01-01T23:59:59.000Z

393

Nuclear reaction analysis of hydrogen in SSC beam pipe materials  

DOE Green Energy (OSTI)

To control the photodesorption of molecular hydrogen, it is advantageous to reduce the amount of hydrogen in candidate SSC beam pipe materials and identify those procedures that: (1) lead to contamination of the beam pipe surface or materials, (2) would reduce the amount of hydrogen on the surface or in the bulk and (3) could be used for in-situ cleaning during Collider assembly or during Collider maintenance. Nuclear Reaction Analysis (NRA) can be used to quantitatively measure the amount of hydrogen on the surface or within half a micron of the surface. The present report discusses data that has been obtained for candidate SSC beam pipe materials (Nitronix 40 Stainless Steel, Nitronix 40 SS coated with electrodeposited copper (Silvex process)), oxygen-free high conductivity copper (Hitachi 101 OFHC) and several miscellaneous samples. The work demonstrates the potential of the technique for characterizing the hydrogen concentration of accelerator beam pipe materials, for assisting in the development of better vacuum system materials for TeV-scale accelerators, and for the development of better beam pipe construction or maintenance procedures for future accelerator projects.

Ruckman, M.W.; Strongin, M. [Brookhaven National Lab., Upton, NY (United States); Lanford, W.A. [State Univ. of New York, Albany, NY (United States). Dept. of Physics

1993-12-31T23:59:59.000Z

394

REVIEW ARTICLE Molecular Anions  

E-Print Network (OSTI)

REVIEW ARTICLE Molecular Anions Jack Simons Chemistry Department, Henry Eyring Center ReceiVed: February 28, 2008 The experimental and theoretical study of molecular anions has undergone on the experimental front. Theoretical developments on the electronic structure and molecular dynamics fronts now

Simons, Jack

395

Molecular Cell Short Article  

E-Print Network (OSTI)

Molecular Cell Short Article Nucleosome Organization Affects the Sensitivity of Gene Expression to Promoter Mutations Gil Hornung,1 Moshe Oren,2 and Naama Barkai1,* 1Department of Molecular Genetics 2Department of Molecular Cell Biology Weizmann Institute of Science, Rehovot, Israel *Correspondence: naama

Barkai, Naama

396

Beam line windows at LAMPF  

Science Conference Proceedings (OSTI)

The A-6 main beam-line window at LAMPF separates the vacuum of the main beam line from the isotope production station, proton irradiation ports, and the beam stop, which operate in air. This window must withstand the design beam current of 1 mA at 800 MeV for periods of at least 3000 hours without failure. The window is water cooled and must be strong enough to withstand the 2.1 MPa (300 psig) cooling water pressure, as well as beam-induced thermal stresses. Two designs have been used to meet these goals, a stepped-plate window and a hemispherical window, both made from a precipitation-hardened nickel base alloy, Alloy 718. Calculations of the temperatures and stresses in each of these windows are presented.

Brown, R.D.; Grisham, D.L.; Lambert, J.E.

1985-01-01T23:59:59.000Z

397

IonBeamMicroFab  

NLE Websites -- All DOE Office Websites (Extended Search)

Ion Beam Manufacture of Microscale Ion Beam Manufacture of Microscale Tools and Components Manufacturing Technologies Sandia Manufacturing Science &Technology's Focused Ion Beam (FIB) laboratory provides an opportunity for research, development and prototyping. Currently, our scientists are devel- oping methods for ion beam sculpting microscale tools, components and devices. This includes shaping of specialty tools such as end-mills, turning tools and indenters. Many of these have been used in ultra-precision machining DOE applications. Additionally, staff are developing the capability to ion mill geo- metrically-complex features and substrates. This includes the ability to sputter predeter- mined curved shapes of various symmetries and periodicities. Capabilities and Expertise * Two custom-built focused ion beam sys-

398

Laser-beam-alignment system  

DOE Patents (OSTI)

A plurality of pivotal reflectors direct a high-power laser beam onto a workpiece, and a rotatable reflector is movable to a position wherein it intercepts the beam and deflects a major portion thereof away from its normal path, the remainder of the beam passing to the pivotal reflectors through an aperture in the rotating reflector. A plurality of targets are movable to positions intercepting the path of light traveling to the pivotal reflectors, and a preliminary adjustment of the latter is made by use of a low-power laser beam reflected from the rotating reflector, after which the same targets are used to make a final adjustment of the pivotal reflectors with the portion of the high-power laser beam passed through the rotating reflector. The system was developed to cut the casings of spent nuclear fuel elements into segments as the initial step in recovering usable fuel. (WHK)

Kasner, W.H.; Racki, D.J.; Swenson, C.E.

1982-02-26T23:59:59.000Z

399

Molecular oxygen in the rho Ophiuchi cloud  

E-Print Network (OSTI)

Molecular oxygen, O2 has been expected historically to be an abundant component of the chemical species in molecular clouds and, as such, an important coolant of the dense interstellar medium. However, a number of attempts from both ground and from space have failed to detect O2 emission. The work described here uses heterodyne spectroscopy from space to search for molecular oxygen in the interstellar medium. The Odin satellite carries a 1.1 m sub-millimeter dish and a dedicated 119 GHz receiver for the ground state line of O2. Starting in 2002, the star forming molecular cloud core rho Oph A was observed with Odin for 34 days during several observing runs. We detect a spectral line at v(LSR) = 3.5 km/s with dv(FWHM) = 1.5 km/s, parameters which are also common to other species associated with rho Ohp A. This feature is identified as the O2 (N_J = 1_1 - 1_0) transition at 118 750.343 MHz. The abundance of molecular oxygen, relative to H2,, is 5E-8 averaged over the Odin beam. This abundance is consistently lower than previously reported upper limits.

B. Larsson; R. Liseau; L. Pagani; P. Bergman; P. Bernath; N. Biver; J. H. Black; R. S. Booth; V. Buat; J. Crovisier; C. L. Curry; M. Dahlgren; P. J. Encrenaz; E. Falgarone; P. A. Feldman; M. Fich; H. G. Flore'n; M. Fredrixon; U. Frisk; G. F. Gahm; M. Gerin; M. Hagstroem; J. Harju; T. Hasegawa; Aa. Hjalmarson; C. Horellou; L. E. B. Johansson; K. Justtanont; A. Klotz; E. Kyroelae; S. Kwok; A. Lecacheux; T. Liljestroem; E. J. Llewellyn; S. Lundin; G. Me'gie; G. F. Mitchell; D. Murtagh; L. H. Nordh; L. -Aa. Nyman; M. Olberg; A. O. H. Olofsson; G. Olofsson; H. Olofsson; G. Persson; R. Plume; H. Rickman; I. Ristorcelli; G. Rydbeck; Aa. Sandqvist; F. v. Sche'ele; G. Serra; S. Torchinsky; N. F. Tothill; K. Volk; T. Wiklind; C. D. Wilson; A. Winnberg; G. Witt

2007-02-19T23:59:59.000Z

400

New aspects of beam-beam interactions in hadron colliders  

Science Conference Proceedings (OSTI)

Beam-beam phenomena have until now limited the beam currents and luminosity achievable in the Tevatron. injected proton currents are about ten times larger than the anti-proton currents so beam-beam effects have largely acted on the anti-protons and at all stages of the operational cycle. The effects of the anti-protons on the protons have until now been relatively benign but that may change at higher anti-proton currents. After 36 bunches of protons are injected and placed on the proton helix, anti-protons are injected four bunches at a time. After all bunches are injected, acceleration to top energy takes bout 85 seconds. After reaching flat top, the optics around the interaction regions (IRs) is changed to lower {beta}* from 1.6 m to 0.35 m at B0 and D0. The beams are brought into collision by collapsing the separation bumps around the IPs. During a high energy physics store each bunch experiences two head-on collisions with bunches in the opposing beam and seventy long-range interactions. At all other stages of the operational cycle, each bunch experiences only long-range interactions--seventy two in all. Performance limitations from beam-beam effects until now have been primarily due to these long-range interactions. The anti-proton losses at 150 GeV have decreased during the last year mostly due to better control of the orbits, tunes and chromaticities. During this period proton intensities have increased about 50%, thus anti-proton losses at 150 GeV have not been very dependent on proton intensities. Anti-proton and proton losses on the ramp together with proton losses at 150 GeV are the dominant contributors to the Tevatron inefficiency.

Tanaji Sen

2003-06-02T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

Laser beam alignment apparatus and method  

DOE Patents (OSTI)

The disclosure relates to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.

Gruhn, Charles R. (Martinez, CA); Hammond, Robert B. (Los Alamos, NM)

1981-01-01T23:59:59.000Z

402

Abbreviated epitaxial growth mode (AGM) method for reducing cost and improving quality of LEDs and lasers  

DOE Patents (OSTI)

The use of an abbreviated GaN growth mode on nano-patterned AGOG sapphire substrates, which utilizes a process of using 15 nm low temperature GaN buffer and bypassing etch-back and recovery processes during epitaxy, enables the growth of high-quality GaN template on nano-patterned AGOG sapphire. The GaN template grown on nano-patterned AGOG sapphire by employing abbreviated growth mode has two orders of magnitude lower threading dislocation density than that of conventional GaN template grown on planar sapphire. The use of abbreviated growth mode also leads to significant reduction in cost of the epitaxy. The growths and characteristics of InGaN quantum wells (QWs) light emitting diodes (LEDs) on both templates were compared. The InGaN QWs LEDs grown on the nano-patterned AGOG sapphire demonstrated at least a 24% enhancement of output power enhancement over that of LEDs grown on conventional GaN templates.

Tansu, Nelson; Chan, Helen M; Vinci, Richard P; Ee, Yik-Khoon; Biser, Jeffrey

2013-09-24T23:59:59.000Z

403

Method of digital epitaxy by externally controlled closed-loop feedback  

DOE Patents (OSTI)

A method and apparatus for digital epitaxy are disclosed. The apparatus includes a pulsed gas delivery assembly that supplies gaseous material to a substrate to form an adsorption layer of the gaseous material on the substrate. Structure is provided for measuring the isothermal desorption spectrum of the growth surface to monitor the active sites which are available for adsorption. The vacuum chamber housing the substrate facilitates evacuation of the gaseous material from the area adjacent the substrate following exposure. In use, digital epitaxy is achieved by exposing a substrate to a pulse of gaseous material to form an adsorption layer of the material on the substrate. The active sites on the substrate are monitored during the formation of the adsorption layer to determine if all the active sites have been filled. Once the active sites have been filled on the growth surface of the substrate, the pulse of gaseous material is terminated. The unreacted portion of the gas pulse is evacuated by continuous pumping. Subsequently, a second pulse is applied when availability of active sites is determined by studying the isothermal desorption spectrum. These steps are repeated until a thin film of sufficient thickness is produced. 4 figs.

Eres, D.; Sharp, J.W.

1994-07-19T23:59:59.000Z

404

Epitaxial synthesis of diamond layers on a monocrystalline diamond substrate in a torch microwave plasmatron  

SciTech Connect

The epitaxial growth of a diamond single-crystal film in a torch microwave discharge excited by a magnetron of a domestic microwave oven with the power of {<=}1 kW in an argon-hydrogen-methane mixture with a high concentration of methane (up to 25% with respect to hydrogen) at atmospheric pressure on a sub-strate of a synthetic diamond single crystal (HPHP) with the orientation (100) and 4 Multiplication-Sign 4 mm in size is obtained. A discharge with the torch diameter of {approx}2 mm and the concentration of the microwave power absorbed in the torch volume of >10{sup 3} W/cm{sup 3} is shown to be effective for epitaxial enlargement of a single crystal of synthetic diamond. The structure of the deposited film with the thickness up to 10 {mu}m with high-quality morphology is investigated with an optical microscope as well as using the methods of the Raman scattering and scanning electron microscopy.

Sergeichev, K. F., E-mail: kserg@fpl.gpi.ru; Lukina, N. A. [Prokhorov Institute of General Physics (Russian Federation)

2011-12-15T23:59:59.000Z

405

Atomic-scale structural analyses of epitaxial Co/Re superlattices  

Science Conference Proceedings (OSTI)

High-resolution transmission electron microscopy and scanning transmission electron microscopy (STEM) have been used to investigate atomic-scale structural properties of Co/Re trilayers and superlattices grown via magnetron sputtering. The sample growth was epitaxial with the (1010) plane of Co and Re parallel to the (1120) plane of Al{sub 2}O{sub 3}, and the [001] direction of Re and Co coinciding with that of the Al{sub 2}O{sub 3}. Both low-angle and high-angle Z-contrast STEM images show a very uniform layer thickness. However, the interface roughness between the Re and Co layers monotonically increases with interface distance from the substrate. These results strongly imply that, in the epitaxial Re/Co superlattice system, interface roughness plays a more important role in the giant magnetoresistance effect than thickness fluctuations of the spacer layer. Previous anisotropic magnetoresistance measurements can be explained in terms of the observed atomic-scale structure.

Xu Wentao; De Long, Lance E.; Charlton, Timothy; Chisholm, Matthew; Lederman, David [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States); Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Oak Ridge National Laboratory, P. O. Box 2008, MS6030-Oak Ridge, Tennessee 37831 (United States); Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States)

2004-11-01T23:59:59.000Z

406

Ferromagnetism in Mn-Implanted Epitaxially Grown Ge on Si(100)  

SciTech Connect

We have studied ferromagnetism of Mn-implanted epitaxial Ge films on silicon. The Ge films were grown by ultrahigh vacuum chemical vapor deposition using a mixture of germane (GeH{sub 4}) and methylgermane (CH{sub 3}GeH{sub 3}) gases with a carbon concentration of less than 1 at. %, and observed surface rms roughness of 0.5 nm, as measured by atomic force microscopy. Manganese ions were implanted in epitaxial Ge films grown on Si (100) wafers to an effective concentration of 16, 12, 6, and 2 at. %. Superconducting quantum interference device measurements showed that only the three highest Mn concentration samples are ferromagnetic, while the fourth sample, with [Mn] = 2 at. %, is paramagnetic. X-ray absorption spectroscopy and x-ray magnetic circular dichroism measurements indicate that localized Mn moments are ferromagnetically coupled below the Curie temperature. Isothermal annealing of Mn-implanted Ge films with [Mn] = 16 at. % at 300 C for up to 1200 s decreases the magnetization but does not change the Curie temperature, suggesting that the amount of the magnetic phase slowly decreases with time at this anneal temperature. Furthermore, transmission electron microscopy and synchrotron grazing incidence x-ray diffraction experiments show that the Mn-implanted region is amorphous, and we believe that it is this phase that is responsible for the ferromagnetism. This is supported by our observation that high-temperature annealing leads to recrystallization and transformation of the material into a paramagnetic phase.

Guchhait, S.; Jamil, M.; Ohldag, H.; Mehta, A.; Arenholz, E.; Lian, G.; Li Fatou, A.; Ferrer, D. A.; Markert, J. T.; Colombo, L.; Banerjee, S. K.

2011-01-05T23:59:59.000Z

407

Process for selectively patterning epitaxial film growth on a semiconductor substrate  

DOE Patents (OSTI)

A process is disclosed for selectively patterning epitaxial film growth on a semiconductor substrate. The process includes forming a masking member on the surface of the substrate, the masking member having at least two layers including a first layer disposed on the substrate and the second layer covering the first layer. A window is then opened in a selected portion of the second layer by removing that portion to expose the first layer thereunder. The first layer is then subjected to an etchant introduced through the window to dissolve a sufficient amount of the first layer to expose the substrate surface directly beneath the window, the first layer being adapted to preferentially dissolve at a substantially greater rate than the second layer so as to create an overhanging ledge portion with the second layer by undercutting the edges thereof adjacent to the window. The epitaxial film is then deposited on the exposed substrate surface directly beneath the window. Finally, an etchant is introduced through the window to dissolve the remainder of the first layer so as to lift-off the second layer and materials deposited thereon to fully expose the balance of the substrate surface.

Sheldon, Peter (Golden, CO); Hayes, Russell E. (Boulder, CO)

1986-01-01T23:59:59.000Z

408

Process for selectively patterning epitaxial film growth on a semiconductor substrate  

DOE Patents (OSTI)

Disclosed is a process for selectively patterning epitaxial film growth on a semiconductor substrate. The process includes forming a masking member on the surface of the substrate, the masking member having at least two layers including a first layer disposed on the substrate and the second layer covering the first layer. A window is then opened in a selected portion of the second layer by removing that portion to expose the first layer thereunder. The first layer is then subjected to an etchant introduced through the window to dissolve the first layer a sufficient amount to expose the substrate surface directly beneath the window, the first layer being adapted to preferentially dissolve at a substantially greater rate than the second layer so as to create an overhanging ledge portion with the second layer by undercutting the edges thereof adjacent the window. The epitaxial film is then deposited on the exposed substrate surface directly beneath the window. Finally, an etchant is introduced through the window to dissolve the remainder of the first layer so as to lift-off the second layer and materials deposited thereon to fully expose the balance of the substrate surface.

Sheldon, P.; Hayes, R.E.

1984-12-04T23:59:59.000Z

409

Rapid liquid phase epitaxial growth studies of GaAs: Final report, July 1984-June 1987  

Science Conference Proceedings (OSTI)

Single crystal layers of gallium arsenide have been grown on (111) and (100) oriented GaAs substrates from a flowing, GaAs saturated, gallium solution with a few degrees temperature differential across the liquid/solid interface. Very high growth rates, on the order of 8..mu..m per minute, have been observed. Such rates are in agreement with the growth theory developed as part of this program, and are about two orders greater than those typically achieved in conventional, static solution, liquid phase epitaxy. Both undoped and p-doped (Si) GaAs layers have been grown and some of their material properties measured. Good crystallinity was inferred from the narrowness of x-ray diffraction lines and from the intensities of the photoluminescence responses of all specimens sampled. While these results do not prove that the epi material is of photovoltaic quality, they indicate both a high crystallographic perfection and a low density of life-time poisoning impurities; conditions which are usually necessary for PV device development. Thus far, smooth surfaces have not been produced directly by the rapid liquid phase epitaxy (RLPE) process. The rough surface morphologies are due, at least in part, to incomplete wipe off of the liquid when the substrate is withdrawn at the end of the growth cycle. Another potential source is growth instabilities which will be discussed later. This report summarizes the three year research program of the RLPE process sponsored by DOE-SOLERAS.

Gerritsen, H.J.; Crisman, E.E.

1987-01-01T23:59:59.000Z

410

LHCb Beam-Gas Imaging Results  

E-Print Network (OSTI)

The high resolution of the LHCb vertex detector makes it possible to perform precise measurements of vertices of beam-gas and beam-beam interactions and allows beam parameters such as positions, angles and widths to be determined. Using the directly measured beam properties the novel beam-gas imaging method is applied in LHCb for absolute luminosity determination. In this contribution we briefly describe the method and the preliminary results obtained with May 2010 data.

P. Hopchev

2011-07-07T23:59:59.000Z

411

OBSERVATION OF STRONG - STRONG AND OTHER BEAM - BEAM EFFECTS IN RHIC.  

SciTech Connect

RHIC is currently the only hadron collider in which strong-strong beam-beam effects can be seen. For the first time, coherent beam-beam modes were observed in a bunched beam hadron collider. Other beam-beam effects in RHIC were observed in operation and in dedicated experiments with gold ions, deuterons and protons. Observations include measurements of beam-beam induced tune shifts, lifetime and emittance growth measurements with and without beam-beam interaction, and background rates as a function of tunes. During ramps unequal radio frequencies in the two rings cause the crossing points to move longitudinally. Thus bunches experience beam-beam interactions only in intervals and the tunes are modulated. In this article we summarize the most important beam-beam observations made so far.

Fischer, W; Brennan, J M; Cameron, P; Connolly, R; Montag, C; Peggs, S; Pilat, F; Ptitsyn, V; Tepikian, S; Trbojevic, D

2003-05-12T23:59:59.000Z

412

Ion Beam Modification of Materials  

SciTech Connect

This volume contains the proceedings of the 14th International Conference on Ion Beam Modification of Materials, IBMM 2004, and is published by Elsevier-Science Publishers as a special issue of Nuclear Instruments and Methods B. The conference series is the major international forum to present and discuss recent research results and future directions in the field of ion beam modification, synthesis and characterization of materials. The first conference in the series was held in Budapest, Hungary, 1978, and subsequent conferences were held every two years at locations around the Globe, most recently in Japan, Brazil, and the Netherlands. The series brings together physicists, materials scientists, and ion beam specialists from all over the world. The official conference language is English. IBMM 2004 was held on September 5-10, 2004. The focus was on materials science involving both basic ion-solid interaction processes and property changes occurring either during or subsequent to ion bombardment and ion beam processing in relation to materials and device applications. Areas of research included Nanostructures, Multiscale Modeling, Patterning of Surfaces, Focused Ion Beams, Defects in Semiconductors, Insulators and Metals, Cluster Beams, Radiation Effects in Materials, Photonic Devices, Ion Implantation, Ion Beams in Biology and Medicine including New Materials, Imaging, and Treatment.

Averback, B; de la Rubia, T D; Felter, T E; Hamza, A V; Rehn, L E

2005-10-10T23:59:59.000Z

413

Intense low energy positron beams  

Science Conference Proceedings (OSTI)

Intense positron beams are under development or being considered at several laboratories. Already today a few accelerator based high intensity, low brightness e{sup +} beams exist producing of the order of 10{sup 8} {minus} 10{sup 9} e{sup +}/sec. Several laboratories are aiming at high intensity, high brightness e{sup +} beams with intensities greater than 10{sup 9} e{sup +}/sec and current densities of the order of 10{sup 13} {minus} 10{sup 14} e{sup +} sec{sup {minus}} {sup 1}cm{sup {minus}2}. Intense e{sup +} beams can be realized in two ways (or in a combination thereof) either through a development of more efficient B{sup +} moderators or by increasing the available activity of B{sup +} particles. In this review we shall mainly concentrate on the latter approach. In atomic physics the main trust for these developments is to be able to measure differential and high energy cross-sections in e{sup +} collisions with atoms and molecules. Within solid state physics high intensity, high brightness e{sup +} beams are in demand in areas such as the re-emission e{sup +} microscope, two dimensional angular correlation of annihilation radiation, low energy e{sup +} diffraction and other fields. Intense e{sup +} beams are also important for the development of positronium beams, as well as exotic experiments such as Bose condensation and Ps liquid studies.

Lynn, K.G.; Jacobsen, F.M.

1993-12-31T23:59:59.000Z

414

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

7-1 7-1 Oct. 26, 2009 Oct. 27, 2009 Oct. 28, 2009 Oct. 29, 2009 Oct. 30, 2009 Oct. 31, 2009 Nov. 01, 2009 CHANGE/8803* C.SMI 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH 8803* C.SMITH BEAM LINE 9-1 Oct. 26, 2009 Oct. 27, 2009 Oct. 28, 2009 Oct. 29, 2009 Oct. 30, 2009 Oct. 31, 2009 Nov. 01, 2009 CHANGE/8861* I.MAT 8861* I.MATHEWS 8861* I.MATHEWS 8861* I.MATHEWS 8861* I.MATHEWS 8861* I.MATHEWS 8861* I.MATHEWS

415

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

7-1 7-1 Nov. 15, 2010 Nov. 16, 2010 Nov. 17, 2010 Nov. 18, 2010 Nov. 19, 2010 Nov. 20, 2010 Nov. 21, 2010 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 2B87 I.SEVRIOUKOVA 2B87 I.SEVRIOUKOVA 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ MC CHECKOUT/2B87 2B87 I.SEVRIOUKOVA 2B87 I.SEVRIOUKOVA 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 8845 A.GONZALEZ 2B87 I.SEVRIOUKOVA 2B87 I.SEVRIOUKOVA 2B87 I.SEVRIOUKOVA BEAM LINE 9-1 Nov. 15, 2010 Nov. 16, 2010 Nov. 17, 2010 Nov. 18, 2010 Nov. 19, 2010 Nov. 20, 2010 Nov. 21, 2010 8866 T.DOUKOV 8866 T.DOUKOV 8866 T.DOUKOV 8866 T.DOUKOV 8866 T.DOUKOV FACI FACI

416

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

Feb. 14, 2005 Feb. 21, 2005 Feb. 28, 2005 Mar. 07, 2005 Feb. 14, 2005 Feb. 21, 2005 Feb. 28, 2005 Mar. 07, 2005 Mar. 14, 2005 Mar. 21, 2005 Mar. 28, 2005 Apr. 04, 2005 Apr. 11, 2005 Apr. 18, 2005 Apr. 25, 2005 May 02, 2005 May 09, 2005 May 16, 2005 May 23, 2005 May 30, 2005 Jun. 06, 2005 Jun. 13, 2005 Jun. 20, 2005 Jun. 27, 2005 Jul. 04, 2005 Jul. 11, 2005 Jul. 18, 2005 Jul. 25, 2005 Aug. 01, 2005 Back to Table of Contents WEEK OF Feb. 14, 2005 Feb. 14, 2005 Feb. 15, 2005 Feb. 16, 2005 Feb. 17, 2005 Feb. 18, 2005 Feb. 19, 2005 Feb. 20, 2005 BEAM LINE 1-5 Feb. 14, 2005 Feb. 15, 2005 Feb. 16, 2005 Feb. 17, 2005 Feb. 18, 2005 Feb. 19, 2005 Feb. 20, 2005 8858 D.HARRINGTON 8858 D.HARRIN/DOWN 8858 D.HARRINGTON 8858 D.HARRINGTON 8858 D.HARRINGTON 8858 D.HARRINGTON 8858 D.HARRINGTON

417

SSRL BEAM PORT SCHEDULE  

NLE Websites -- All DOE Office Websites (Extended Search)

1, 2013 Nov. 18, 2013 Nov. 25, 2013 Dec. 02, 2013 1, 2013 Nov. 18, 2013 Nov. 25, 2013 Dec. 02, 2013 Dec. 09, 2013 Dec. 16, 2013 Dec. 23, 2013 Dec. 30, 2013 Jan. 06, 2014 Jan. 13, 2014 Jan. 20, 2014 Jan. 27, 2014 Feb. 03, 2014 Feb. 10, 2014 Feb. 17, 2014 Feb. 24, 2014 Back to Table of Contents WEEK OF Nov. 11, 2013 Nov. 11, 2013 Nov. 12, 2013 Nov. 13, 2013 Nov. 14, 2013 Nov. 15, 2013 Nov. 16, 2013 Nov. 17, 2013 BEAM LINE 7-1 Nov. 11, 2013 Nov. 12, 2013 Nov. 13, 2013 Nov. 14, 2013 Nov. 15, 2013 Nov. 16, 2013 Nov. 17, 2013 8803 C.Smith 8803 C.Smith 8803 C.Smith 8803 C.Smith 8803 C.Smith 4B02 A.Yeh 8050 C.Smith 8803 C.Smith 8803 C.Smith 8803 C.Smith 8803 C.Smith Unscheduled MC CHECKOUT/8050 8050 C.Smith

418

Electron beam machining using rotating and shaped beam power distribution  

DOE Patents (OSTI)

An apparatus and method for electron beam (EB) machining (drilling, cutting and welding) that uses conventional EB guns, power supplies, and welding machine technology without the need for fast bias pulsing technology. The invention involves a magnetic lensing (EB optics) system and electronic controls to: 1) concurrently bend, focus, shape, scan, and rotate the beam to protect the EB gun and to create a desired effective power-density distribution, and 2) rotate or scan this shaped beam in a controlled way. The shaped beam power-density distribution can be measured using a tomographic imaging system. For example, the EB apparatus of this invention has the ability to drill holes in metal having a diameter up to 1000 .mu.m (1 mm or larger), compared to the 250 .mu.m diameter of laser drilling.

Elmer, John W. (Pleasanton, CA); O' Brien, Dennis W. (Livermore, CA)

1996-01-01T23:59:59.000Z

419

Compact Alignment for Diagnostic Laser Beams  

Physicist and optical engineer Mike Rushford developed the laser beam . centering and pointing system. The laser beam . centering and pointing system

420

NIST SURF: Beamline 10: Electron beam imaging  

Science Conference Proceedings (OSTI)

Beamline 10: Electron beam imaging. Description: ... In its unperturbed state, the vertical electron beam size is quite small, in the order of a few 10 m. ...

2012-11-19T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

PowerBeam Inc | Open Energy Information  

Open Energy Info (EERE)

PowerBeam, Inc. Place Sunnyvale, California Zip CA 94085 Product PowerBeam holds the patent to a power transmission technology that produces wireless electricity. Coordinates...

422

Structure and growth morphology of an archetypal system for organic epitaxy: PTCDA on Ag,,111... B. Krause,1  

E-Print Network (OSTI)

.10.Aj, 61.66.Hq I. INTRODUCTION Over the last few years, organic semiconductors have ex- periencedStructure and growth morphology of an archetypal system for organic epitaxy: PTCDA on Ag,,111... B; revised manuscript received 24 July 2002; published 10 December 2002 The planar organic molecule 3

Schreiber, Frank

423

High efficiency epitaxial optical reflector solar cells. Final subcontract report, 1 January 1990--31 October 1992  

DOE Green Energy (OSTI)

This report describes work to test the feasibility of a new solar cell concept -- the epitaxial optical reflector (EOR) solar cell. This cell concept alters current designs for high efficiency cells by changing the optical absorption efficiency of single cells. The change is introduced by the use an epitaxial multilayer reflector as an integral part of the cell to increase the optical path length of certain wavelengths of light in the cell. These changes are expected to increase the open circuit voltage at which power is extracted from the cell. The program is designed to test the feasibility of the use of a broad band epitaxial multilayer reflector grown as an integral part of the device structure to reflect the near-band-edge light back through the device for a second absorption pass. This second pass allows the design of a solar cell with a thinner base, and the use of the epitaxial reflector as a heterojunction carrier-reflecting barrier at the rear of the device. The thinner cell design and altered carrier profile that results from the light- and carrier-reflecting barrier will decrease the carrier concentration gradient and increase the open circuit voltage. The program is structured to have three tasks: (1) Solar Cell and Reflector Modeling, (2) Materials Growth and Optimization, and (3) Solar Cell Fabrication and Characterization.

Dapkus, P.D.; Hummel, S.G. [University of Southern California, Los Angeles, CA (United States)

1993-08-01T23:59:59.000Z

424

Direct measurement of interfacial structure in epitaxial Gd2O3 on GaAs (001) using scanning tunneling microscopy  

Science Conference Proceedings (OSTI)

The epitaxial growth of Gd"2O"3 on GaAs (001) has given a low interfacial density of states, resulting in the demonstration of the first inversion-channel GaAs metal-oxide-semiconductor field-effect transistor. Motivated by the significance of this discovery, ... Keywords: Electronic information, GaAs, Gd2O3, Interfacial stacking, Scanning tunneling microscopy

Y. P. Chiu; M. C. Shih; B. C. Huang; J. Y. Shen; M. L. Huang; W. C. Lee; P. Chang; T. H. Chiang; M. Hong; J. Kwo

2011-07-01T23:59:59.000Z

425

MEIS: Molecular Environmental & Interface Science  

NLE Websites -- All DOE Office Websites (Extended Search)

People People BL 11-2 Reports &Publications Model Compound Library SixPACK Glitch Curves MES User Resources & Instrumentation Environmental Remediation Science at SSRL MEIS Home SSRL Stanford EMSI SLAC Beam line resources and instrumentation Fundamental and applied research Why synchrotrons for environmental science? Molecular Environmental Science (MES) research at SSRL focuses on the fundamental interfacial, molecular- and nano-scale processes that control contaminant and nutrient cycling in the biosphere with the goal of elucidating global elemental cycles and anthropogenic influences on the environment. Key areas of investigation include the: (a) Structural chemistry of water and dissolved solutes, (b) Structural chemistry and reactivity of complex natural environmental materials with respect to heavy

426

Circular, confined distribution for charged particle beams  

DOE Patents (OSTI)

A charged particle beam line is formed with magnetic optics that manipulate the charged particle beam to form the beam having a generally rectangular configuration to a circular beam cross-section having a uniform particle distribution at a predetermined location. First magnetic optics form a charged particle beam to a generally uniform particle distribution over a square planar area at a known first location. Second magnetic optics receive the charged particle beam with the generally square configuration and affect the charged particle beam to output the charged particle beam with a phase-space distribution effective to fold corner portions of the beam toward the core region of the beam. The beam forms a circular configuration having a generally uniform spatial particle distribution over a target area at a predetermined second location. 26 figs.

Garnett, R.W.; Dobelbower, M.C.

1995-11-21T23:59:59.000Z

427

Circular, confined distribution for charged particle beams  

DOE Patents (OSTI)

A charged particle beam line is formed with magnetic optics that manipulate the charged particle beam to form the beam having a generally rectangular configuration to a circular beam cross-section having a uniform particle distribution at a predetermined location. First magnetic optics form a charged particle beam to a generally uniform particle distribution over a square planar area at a known first location. Second magnetic optics receive the charged particle beam with the generally square configuration and affect the charged particle beam to output the charged particle beam with a phase-space distribution effective to fold corner portions of the beam toward the core region of the beam. The beam forms a circular configuration having a generally uniform spatial particle distribution over a target area at a predetermined second location.

Garnett, Robert W. (Los Alamos, NM); Dobelbower, M. Christian (Toledo, OH)

1995-01-01T23:59:59.000Z

428

Particle beam fusion  

SciTech Connect

Today, in keeping with Sandia Laboratories` designation by the Department of Energy as the lead laboratory for the pulsed power approach to fusion, its efforts include major research activities and the construction of new facilities at its Albuquerque site. Additionally, in its capacity as lead laboratory, Sandia coordinates DOE-supported pulsed power fusion work at other government operated laboratories, with industrial contractors, and universities. The beginning of Sandia`s involvement in developing fusion power was an outgrowth of its contributions to the nation`s nuclear weapon program. The Laboratories` work in the early 1960`s emphasized the use of pulsed radiation environments to test the resistance of US nuclear weapons to enemy nuclear bursts. A careful study of options for fusion power indicated that Sandia`s expertise in the pulsed power field could provide a powerful match to ignite fusion fuel. Although creating test environments is an achieved goal of Sandia`s overall program, this work and other military tasks protected by appropriate security regulations will continue, making full use of the same pulsed power technology and accelerators as the fusion-for-energy program. Major goals of Sandia`s fusion program including the following: (1) complete a particle accelerator to deliver sufficient beam energy for igniting fusion targets; (2) obtain net energy gain, this goal would provide fusion energy output in excess of energy stored in the accelerator; (3) develop a technology base for the repetitive ignition of pellets in a power reactor. After accomplishing these goals, the technology will be introduced to the nation`s commercial sector.

1980-12-31T23:59:59.000Z

429

Repetitively pumped electron beam device  

DOE Patents (OSTI)

Disclosed is an apparatus for producing fast, repetitive pulses of controllable length of an electron beam by phased energy storage in a transmission line of length matched to the number of pulses and specific pulse lengths desired. 12 figs.

Schlitt, L.G.

1979-07-24T23:59:59.000Z

430

INSTABILITIES OF RELATIVISTIC PARTICLE BEAMS  

E-Print Network (OSTI)

1965). K. W. Robinson, in SLAC Storage Ring Stumner Study,Beams, a Summary. Report, SLAC-49, L. J. Laslett, V. K.La.slett and A. M. Sessler, in SLAC-49, Sept. 1965 (see Ref.

Sessler, Andrew M.

2008-01-01T23:59:59.000Z

431

Center for Beam Physics, 1992  

Science Conference Proceedings (OSTI)

This report contains the following information on the center for beam physics: Facilities; Organizational Chart; Roster; Profiles of Staff; Affiliates; Center Publications (1991--1993); and 1992 Summary of Activities.

Not Available

1993-06-01T23:59:59.000Z

432

Repetitively pumped electron beam device  

DOE Patents (OSTI)

Apparatus for producing fast, repetitive pulses of controllable length of an electron beam by phased energy storage in a transmission line of length matched to the number of pulses and specific pulse lengths desired.

Schlitt, Leland G. (Livermore, CA)

1979-01-01T23:59:59.000Z

433

The Fermilab neutrino beam program  

Science Conference Proceedings (OSTI)

This talk presents an overview of the Fermilab Neutrino Beam Program. Results from completed experiments as well as the status and outlook for current experiments is given. Emphasis is given to current activities towards planning for a future program.

Rameika, Regina A.; /Fermilab

2007-01-01T23:59:59.000Z

434

Confined energy distribution for charged particle beams  

SciTech Connect

A charged particle beam is formed to a relatively larger area beam which is well-contained and has a beam area which relatively uniformly deposits energy over a beam target. Linear optics receive an accelerator beam and output a first beam with a first waist defined by a relatively small size in a first dimension normal to a second dimension. Nonlinear optics, such as an octupole magnet, are located about the first waist and output a second beam having a phase-space distribution which folds the beam edges along the second dimension toward the beam core to develop a well-contained beam and a relatively uniform particle intensity across the beam core. The beam may then be expanded along the second dimension to form the uniform ribbon beam at a selected distance from the nonlinear optics. Alternately, the beam may be passed through a second set of nonlinear optics to fold the beam edges in the first dimension. The beam may then be uniformly expanded along the first and second dimensions to form a well-contained, two-dimensional beam for illuminating a two-dimensional target with a relatively uniform energy deposition.

Jason, Andrew J. (Los Alamos, NM); Blind, Barbara (Los Alamos, NM)

1990-01-01T23:59:59.000Z

435

Beam cooling: Principles and achievements  

SciTech Connect

After a discussion of Liouville's theorem, and its implications for beam cooling, a brief description is given of each of the various methods of beam cooling: stochastic, electron, radiation, laser, ionization, etc. For each, we present the type of particle for which it is appropriate, its range of applicability, and the currently achieved degree of cooling. For each method we also discuss the present applications and, also, possible future developments and further applications.

Mohl, Dieter; Sessler, Andrew M.

2003-05-18T23:59:59.000Z

436

The Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

LBNL Masthead A-Z Index Berkeley Lab masthead Phone Book Jobs Search The Molecular Foundry Home DOE - Office of Science ABOUT US FACILITIESCAPABILITIES RESEARCH BECOMING A USER...

437

The Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

PEOPLE JOB OPPORTUNITIES USER'S ASSOCIATION CONTACT US Foundry Intranet DOE Basic Energy Sciences User Facilities Molecular Foundry Seminar "Atomic Structure and Applications...

438

The Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

PEOPLE JOB OPPORTUNITIES USER'S ASSOCIATION CONTACT US Foundry Intranet DOE Basic Energy Sciences User Facilities Molecular Foundry Seminar Mineralization at the Organic...

439

The Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

PEOPLE JOB OPPORTUNITIES USER'S ASSOCIATION CONTACT US Foundry Intranet DOE Basic Energy Sciences User Facilities Molecular Foundry Seminar "What Happens to Crystals When...

440

The Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

Brett Helms, Berkeley Lab Title: Building Our Understanding of Nanocrystal Surface Structure Using Heterometallic Molecular Beacons Location: 67-3111 Chemla room View the Foundry...

Note: This page contains sample records for the topic "molecular beam epitaxy" 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

A Molecular Simulation Study  

Science Conference Proceedings (OSTI)

Presentation Title, Enhanced CO2 Adsorption in Ti-exchanged Zirconium Organic Frameworks A Molecular Simulation Study. Author(s), Ravichandar Babarao...

442

Turbulent molecular clouds  

E-Print Network (OSTI)

Stars form within molecular clouds but our understanding of this fundamental process remains hampered by the complexity of the physics that drives their evolution. We review our observational and theoretical knowledge of molecular clouds trying to confront the two approaches wherever possible. After a broad presentation of the cold interstellar medium and molecular clouds, we emphasize the dynamical processes with special focus to turbulence and its impact on cloud evolution. We then review our knowledge of the velocity, density and magnetic fields. We end by openings towards new chemistry models and the links between molecular cloud structure and star--formation rates.

Hennebelle, Patrick

2012-01-01T23:59:59.000Z

443

The Molecular Foundry  

NLE Websites -- All DOE Office Websites (Extended Search)

Seminar Schedule Abstract: The intriguing prospects of molecular electronics, nanotechnology, biomaterials, and the aim to close the gap between synthetic and biological...

444

Educational Molecular Biology Games  

NLE Websites -- All DOE Office Websites (Extended Search)

Molecular Biology Games Do you have a great game? Please click our Ideas page. Featured Games: Biology Games fom biologyjunction.com Biology Games fom biologyjunction.com...

445

Direct e-beam lithography of PDMS  

Science Conference Proceedings (OSTI)

In this paper, the viability of directly exposing thin films of liquid poly(dimethylsiloxane) (PDMS) to electron beam (e-beam) irradiation using e-beam lithographic methods for the purpose of creating permanent micro-scale components has been investigated. ... Keywords: Lithography, PDMS, Poly(dimethylsiloxane), e-Beam

J. Bowen; D. Cheneler; A. P. G. Robinson

2012-09-01T23:59:59.000Z

446

BEAM SCRUBBING FOR RHIC POLARIZED PROTON RUN.  

SciTech Connect

One of the intensity limiting factor of RHIC polarized proton beam is the electron cloud induced pressure rise. A beam scrubbing study shows that with a reasonable period of time of running high intensity 112-bunch proton beam, the pressure rise can be reduced, allowing higher beam intensity.

ZHANG,S.Y.FISCHER,W.HUANG,H.ROSER,T.

2004-07-05T23:59:59.000Z

447

High Island Densities and Long Range Repulsive Interactions: Fe on Epitaxial Graphene  

SciTech Connect

The understanding of metal nucleation on graphene is essential for promising future applications, especially of magnetic metals which can be used in spintronics or computer storage media. A common method to study the grown morphology is to measure the nucleated island density n as a function of growth parameters. Surprisingly, the growth of Fe on graphene is found to be unusual because it does not follow classical nucleation: n is unexpectedtly high, it increases continuously with the deposited amount ? and shows no temperature dependence. These unusual results indicate the presence of long range repulsive interactions. Kinetic Monte Carlo simulations and density functional theory calculations support this conclusion. In addition to answering an outstanding question in epitaxial growth, i.e., to find systems where long range interactions are present, the high density of magnetic islands, tunable with ?, is of interest for nanomagnetism applications.

Binz, Steven M.; Hupalo, Myron; Liu, Xiaojie; Wang, Cai-Zhuang; Lu, Wen-Cai; Thiel, Kai-Ming; Conrad, E.H.; Tringides, Michael C.

2012-07-13T23:59:59.000Z

448

Pulsed atomic layer epitaxy of quaternary AlInGaN layers  

Science Conference Proceedings (OSTI)

In this letter, we report on a material deposition scheme for quaternary Al{sub x}In{sub y}Ga{sub 1-x--y}N layers using a pulsed atomic layer epitaxy (PALE) technique. The PALE approach allows accurate control of the quaternary layer composition and thickness by simply changing the number of aluminum, indium, and gallium pulses in a unit cell and the number of unit cell repeats. Using PALE, AlInGaN layers with Al mole fractions in excess of 40% and strong room-temperature photoluminescence peaks at 280 nm can easily be grown even at temperatures lower than 800{sup o}C. {copyright} 2001 American Institute of Physics.

Zhang, J.; Kuokstis, E.; Fareed, Q.; Wang, H.; Yang, J.; Simin, G.; Asif Khan, M.; Gaska, R.; Shur, M.

2001-08-13T23:59:59.000Z

449

Improved InGaN epitaxy yield by precise temperature measurement :yearly report 1.  

SciTech Connect

This Report summarizes the first year progress (October 1, 2004 to September 30, 2005) made under a NETL funded project entitled ''Improved InGaN Epitaxy Yield by Precise Temperature Measurement''. This Project addresses the production of efficient green LEDs, which are currently the least efficient of the primary colors. The Project Goals are to advance IR and UV-violet pyrometry to include real time corrections for surface emissivity on multiwafer MOCVD reactors. Increasing wafer yield would dramatically reduce high brightness LED costs and accelerate the commercial manufacture of inexpensive white light LEDs with very high color quality. This work draws upon and extends our previous research (funded by DOE) that developed emissivity correcting pyrometers (ECP) based on the high-temperature GaN opacity near 400 nm (the ultraviolet-violet range, or UVV), and the sapphire opacity in the mid-IR (MIR) near 7.5 microns.

Koleske, Daniel David; Creighton, James Randall; Russell, Michael J.; Fischer, Arthur Joseph

2006-08-01T23:59:59.000Z

450

Growth of vertical-cavity surface emitting lasers by metalorganic vapor phase epitaxy  

SciTech Connect

We present growth and characterization of visible and near-infrared vertical-cavity surface emitting lasers (VCSELs) grown by metalorganic vapor phase epitaxy. Discussions on the growth issue of VCSEL materials include growth rate and composition control using an {ital in}{ital situ} normal-incidence reflectometer, comprehensive p- and n-type doping study in AlGaAs by CCl{sub 4} and Si{sub 2}H{sub 6} over the entire composition range, and optimization of ultra-high material uniformity. We also demonstrate our recent achievements of all-AlGaAs VCSELs which include the first room-temperature continuous- wave demonstration of 700-nm red VCSELs and high-efficiency and low- threshold voltage 850-nm VCSELs.

Hou, H.Q.; Hammons, B.E.; Crawford, M.H.; Lear, K.L.; Choquette, K.D.

1996-10-01T23:59:59.000Z

451

Excitation Power Dependence Of Photoluminescence From GaAs Quantum Dot Prepared By Droplet Epitaxy Method  

Science Conference Proceedings (OSTI)

GaAs quantum dot (QD) was grown by droplet epitaxy (DE) method and the excitation power dependence of photoluminescence (PL) were carried out. To investigate the effect of annealing temperature on QDs optical properties, the two step RTA process was carried out in a various temperature range from 800 to 1000 deg. C. As the thermal annealing temperature increases, the PL peak position is blue-shifted due to the change of the composition and size distribution of QDs, and the highest PL intensity is observed at the sample annealed at 900 deg. C. The integrated PL intensity (I{sub PL}) is plotted against the excitation density in a log-log scale and the slope was calculated.

Choi, H. Y.; Kim, D. Y.; Cho, M. Y.; Kim, G. S.; Jeon, S. M.; Yim, K. G.; Kim, M. S.; Leem, J. Y. [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Gimhae (Korea, Republic of); Lee, D. Y. [Epi-manufacturing Technology, Samsung LED Co., Ltd., Suwon (Korea, Republic of); Kim, J. S. [Division of Advanced Materials Engineering, Chonbuk National University, Jeonju (Korea, Republic of); Kim, J. S. [Department of Physics, Yeungnam University, Gyeongsan (Korea, Republic of); Son, J. S. [Department of Visual Optics, Kyungwoon University, Gumi (Korea, Republic of); Lee, J. I. [Advanced Instrument Technology Center, Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

2011-12-23T23:59:59.000Z

452

Waveguiding-assisted random lasing in epitaxial ZnO thin film  

E-Print Network (OSTI)

Zinc Oxide thin films were grown on c-sapphire substrates using pulsed laser deposition. Pump power dependence of surface emission spectra, acquired using a quadrupled 266 nm laser, revealed room temperature stimulated emission (threshold of 900 kW/cm2). Time dependent spectral analysis plus gain measurements of single-shot, side-emission, spectra pumped with a nitrogen laser revealed random lasing indicative of the presence of self-forming laser cavities. It is suggested that random lasing in an epitaxial system rather than a 3-dimensional configuration of disordered scattering elements, was due to waveguiding in the film. Waveguiding causes light to be amplified within randomly-formed closed-loops acting as lasing cavities.

Dupont, P -H; Rogers, D J; Thrani, F Hosseini; Lrondel, G

2013-01-01T23:59:59.000Z

453

Nanoporous films for epitaxial growth of single crystal semiconductor materials : final LDRD report.  

Science Conference Proceedings (OSTI)

This senior council Tier 1 LDRD was focused on exploring the use of porous growth masks as a method for defect reduction during heteroepitaxial crystal growth. Initially our goal was to investigate porous silica as a growth mask, however, we expanded the scope of the research to include several other porous growth masks on various size scales, including mesoporous carbon, photolithographically patterned SU-8 and carbonized SU-8 structures. Use of photolithographically defined growth templates represents a new direction, unique in the extensive literature of p