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1

Molecular Beam Epitaxy, Multi-source | EMSL  

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

beam epitaxy, is examined using a combination... Self-corrected Sensors Based On Atomic Absorption Spectroscopy For Atom Flux Measurements In Molecular Beam Epitaxy. A...

2

Molecular Beam Epitaxy, Multi-source | EMSL  

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

fundamental insight into water splitting for hydrogen... Self-corrected Sensors Based On Atomic Absorption Spectroscopy For Atom Flux Measurements In Molecular Beam Epitaxy. A...

3

A molecular beam epitaxy facility for in situ neutron scattering  

SciTech Connect (OSTI)

A molecular beam epitaxy (MBE) facility has been built to enable in situ neutron scattering measurements during growth of epitaxial layers. While retaining the full capabilities of a research MBE chamber, this facility has been optimized for polarized neutron reflectometry measurements. Optimization includes a compact lightweight portable design, a neutron window, controllable magnetic field, deposition across a large 76 mm diameter sample with exceptional flux uniformity, and sample temperatures continuously controllable from 38 to 1375 K. A load lock chamber allows for sample insertion, storage of up to 4 samples, and docking with other facilities. The design and performance of this chamber are described here.

Dura, J. A.; LaRock, J. [NIST Center for Neutron Research, 100 Bureau Dr. MS 6102, Gaithersburg, Maryland 20899 6102 (United States)

2009-07-15T23:59:59.000Z

4

Controlled oxygen doping of GaN using plasma assisted molecular-beam epitaxy  

E-Print Network [OSTI]

Controlled oxygen doping of GaN using plasma assisted molecular-beam epitaxy A. J. Ptak, L. J-assisted molecular-beam epitaxy to study the dependence of oxygen incorporation on polarity and oxygen partial pressure. Oxygen incorporates at a rate ten times faster on nitrogen-polar GaN than on the Ga polarity

Myers, Tom

5

Photoconductivity of germanium tin alloys grown by molecular beam epitaxy  

SciTech Connect (OSTI)

Photocurrent spectroscopy was used to measure the infrared absorption of germanium-tin alloys grown by molecular beam epitaxy. To study dependence on Sn composition, the photocurrent was measured at 100 K on alloys of Ge{sub 1-x}Sn{sub x} with atomic percentages of Sn up to 9.8%. The optical absorption coefficient was calculated from the photocurrent, and it was found that the absorption edge and extracted bandgap energy decreased with increasing Sn content. For all Ge{sub 1-x}Sn{sub x} samples, a fundamental bandgap below that of bulk Ge was observed, and a bandgap energy as low as 0.624 eV was found for a Sn percentage of 9.8% at 100 K.

Coppinger, Matthew; Hart, John; Bhargava, Nupur; Kim, Sangcheol; Kolodzey, James [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States)] [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States)

2013-04-08T23:59:59.000Z

6

Electron Beam Source Molecular Beam Epitaxy of AlxGal?xAs Graded Band Gap Device Structures  

Science Journals Connector (OSTI)

A new method has been developed for the growth of graded band-gap AlxGal?xAs alloys by molecular beam epitaxy which is based upon electron. beam evaporation of the Group III elements ... . The large dynamic respo...

R. J. Malik; A. F. J. Levi; B. F. Levine…

1989-01-01T23:59:59.000Z

7

Molecular-beam epitaxy growth and characterization of mid-infrared quantum cascade laser structures  

Science Journals Connector (OSTI)

The development of molecular-beam epitaxy (MBE) of GaAs/AlGaAs heterostructures, used for fabrication of ~9?m quantum cascade lasers (QCLs), is reported. The X-ray diffractometry (XRD) structural characterization, as an integral part of this process, ... Keywords: GaAs/AlGaAs lasers, Intersubband transitions, Mid-infrared, Molecular-beam epitaxy, Quantum cascade laser, Unipolar devices

Kamil Kosiel; Justyna Kubacka-Traczyk; Piotr Karbownik; Anna Szerling; Jan Muszalski; Maciej Bugajski; Przemek Romanowski; Jaros?aw Gaca; Marek Wójcik

2009-03-01T23:59:59.000Z

8

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.

9

Non-adiabatic ab initio molecular dynamics of supersonic beam epitaxy of silicon carbide at room temperature  

E-Print Network [OSTI]

Non-adiabatic ab initio molecular dynamics of supersonic beam epitaxy of silicon carbide at room-adiabatic ab initio molecular dynamics of supersonic beam epitaxy of silicon carbide at room temperature Simone film crystal growth of silicon carbide (SiC), a semiconductor syn- thesized to replace silicon in harsh

Alfè, Dario

10

Low-temperature grown graphene films by using molecular beam epitaxy  

SciTech Connect (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

11

Molecular Beam Epitaxial Growth of GaAs on (631) Oriented Substrates  

SciTech Connect (OSTI)

In this work, we report the study of the homoepitaxial growth of GaAs on (631) oriented substrates by molecular beam epitaxy (MBE). We observed the spontaneous formation of a high density of large scale features on the surface. The hilly like features are elongated towards the [-5, 9, 3] direction. We show the dependence of these structures with the growth conditions and we present the possibility of to create quantum wires structures on this surface.

Cruz Hernandez, Esteban; Rojas Ramirez, Juan-Salvador; Contreras Hernandez, Rocio; Lopez Lopez, Maximo [Physics Department, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 14-740, Mexico D.F., 07000 (Mexico); Pulzara Mora, Alvaro [Universidad Nacional de Colombia - Sede Manizales, A. A. 127 (Colombia); Mendez Garcia, Victor H. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Av. Karakorum 1470, Lomas 4a Seccion, C.P. 78210, San Luis Potosi (Mexico)

2007-02-09T23:59:59.000Z

12

(In,Mn)As quantum dots: Molecular-beam epitaxy and optical properties  

SciTech Connect (OSTI)

Self-assembled (In,Mn)As quantum dots are synthesized by molecular-beam epitaxy on GaAs (001) substrates. The experimental results obtained by transmission electron microscopy show that doping of the central part of the quantum dots with Mn does not bring about the formation of structural defects. The optical properties of the samples, including those in external magnetic fields, are studied.

Bouravleuv, A. D., E-mail: bour@mail.ioffe.ru; Nevedomskii, V. N. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Ubyivovk, E. V. [St. Petersburg State University (Russian Federation)] [St. Petersburg State University (Russian Federation); Sapega, V. F. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Khrebtov, A. I. [St. Petersburg Academic University, Nanotechnology Research and Education Centre (Russian Federation)] [St. Petersburg Academic University, Nanotechnology Research and Education Centre (Russian Federation); Samsonenko, Yu. B.; Cirlin, G. E.; Ustinov, V. M. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

2013-08-15T23:59:59.000Z

13

Growth of InGaAsP by molecular beam epitaxy  

SciTech Connect (OSTI)

Molecular beam epitaxy has been used to grow good quality films of InGaAsP on InP substrates. The films have been characterized using infrared absorption, electroreflectance, x-ray diffraction, reflection electron diffraction, and Hall measurements. Lattice matching was achieved and room-temperature mobilities up to 4600 cm/sup 2/ V/sup -1/ s/sup -1/ were measured.

Holah, G.D.; Eisele, F.L.; Meeks, E.L.; Cox, N.W.

1982-12-01T23:59:59.000Z

14

Antimony-assisted carbonization of Si(111) with solid source molecular beam epitaxy  

SciTech Connect (OSTI)

The carbonization of an antimony-terminated Si (111) surface in a solid source molecular beam epitaxy system is presented. Reflection high-energy electron diffraction, atomic force microscopy, x-ray photoelectron spectroscopy, and cross-sectional transmission electron microscopy are used to characterize samples grown with and without antimony termination. It is shown that the antimony-terminated surface promotes the formation of thin, smooth and continuous SiC films at a relatively low temperature of 800 °C.

Hackley, Justin; Richardson, Christopher J. K. [Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740 (United States)] [Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740 (United States); Sarney, Wendy L. [U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783 (United States)] [U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783 (United States)

2013-11-15T23:59:59.000Z

15

Nanostructure formation during ion assisted growth of GaN by molecular beam epitaxy Bentao Cui and P.I. Cohen  

E-Print Network [OSTI]

Nanostructure formation during ion assisted growth of GaN by molecular beam epitaxy Bentao Cui and P.I. Cohen Department of Electrical and Computer Engineering and Department of Chemical Engineering Prairie, MN 55344 (Dated: March 4, 2005) Ion beam assisted molecular beam epitaxy was used to grow Ga

Cohen, Philip I.

16

Real-time reflectance-difference spectroscopy of GaAs molecular beam epitaxy homoepitaxial growth  

SciTech Connect (OSTI)

We report on real time-resolved Reflectance-difference (RD) spectroscopy of GaAs(001) grown by molecular beam epitaxy, with a time-resolution of 500 ms per spectrum within the 2.3–4.0 eV photon energy range. Through the analysis of transient RD spectra we demonstrated that RD line shapes are comprised of two components with different physical origins and determined their evolution during growth. Such components were ascribed to the subsurface strain induced by surface reconstruction and to surface stoichiometry. Results reported in this paper render RD spectroscopy as a powerful tool for the study of fundamental processes during the epitaxial growth of zincblende semiconductors.

Lastras-Martínez, A., E-mail: alm@cactus.iico.uaslp.mx, E-mail: alastras@gmail.com; Ortega-Gallegos, J.; Guevara-Macías, L. E.; Nuñez-Olvera, O.; Balderas-Navarro, R. E.; Lastras-Martínez, L. F. [Instituto de Investigación en Comunicación Optica, Universidad Autónoma de San Luis Potosí, Alvaro Obregón 64, San Luis Potosí, SLP 78000 (Mexico); Lastras-Montaño, L. A. [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Lastras-Montaño, M. A. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, Santa Barbara, California 93106 (United States)

2014-03-01T23:59:59.000Z

17

Lattice constant and substitutional composition of GeSn alloys grown by molecular beam epitaxy  

SciTech Connect (OSTI)

Single crystal epitaxial Ge{sub 1?x}Sn{sub x} alloys with atomic fractions of tin up to x = 0.145 were grown by solid source molecular beam epitaxy on Ge (001) substrates. The Ge{sub 1?x}Sn{sub x} alloys formed high quality, coherent, strained layers at growth temperatures below 250 °C, as shown by high resolution X-ray diffraction. The amount of Sn that was on lattice sites, as determined by Rutherford backscattering spectrometry channeling, was found to be above 90% substitutional in all alloys. The degree of strain and the dependence of the effective unstrained bulk lattice constant of Ge{sub 1?x}Sn{sub x} alloys versus the composition of Sn have been determined.

Bhargava, Nupur; Coppinger, Matthew; Prakash Gupta, Jay; Kolodzey, James [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States)] [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States); Wielunski, Leszek [Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States)] [Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States)

2013-07-22T23:59:59.000Z

18

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

SciTech Connect (OSTI)

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

19

Molecular beam epitaxial growth of Si1?xGex/Si pseudomorphic layers using disilane and germanium  

Science Journals Connector (OSTI)

Molecular beam epitaxial growth of pseudomorphic Si1?xGex/Si layers using disilane (Si2H6) and elemental germanium has been studied for the first time. It is found that at a fixed flow rate of Si2H6, the germaniu...

S. H. Li; P. K. Bhattacharya; R. Malik; E. Gulari

1993-07-01T23:59:59.000Z

20

Electrical properties of scandium nitride epitaxial films grown on (100) magnesium oxide substrates by molecular beam epitaxy  

SciTech Connect (OSTI)

Scandium nitride (ScN) films were grown on (100) MgO single crystals by a molecular beam epitaxy method. The effects of growth conditions, including [Sc]/[N] ratio, growth temperature, and nitrogen radical state, on the electrical properties of the ScN films were studied. The ScN films comprised many small columnar grains. Hall coefficient measurements confirmed that the ScN films were highly degenerate n-type semiconductors and that the carrier concentration of the ScN films was sensitive to the growth temperature and the nitrogen radical states during the film growth. The carrier concentrations of the ScN films ranged from 10{sup 19}–10{sup 21} cm{sup ?3} while the Hall mobilities ranged from 50–130 cm{sup 2}·V{sup ?1}·s{sup ?1} for undoped films. The temperature-dependent Hall coefficient measurements showed that the carrier concentration is nearly independent of temperature, indicating that the change in resistivity with temperature is explained by a change in the Hall mobility. The temperature-dependence of the Hall mobility was strongly affected by the growth conditions.

Ohgaki, Takeshi; Watanabe, Ken; Adachi, Yutaka; Sakaguchi, Isao; Hishita, Shunichi; Ohashi, Naoki; Haneda, Hajime [Environment and Energy Materials Research Division, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)] [Environment and Energy Materials Research Division, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

2013-09-07T23:59:59.000Z

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

Antimony segregation in stressed SiGe heterostructures grown by molecular beam epitaxy  

SciTech Connect (OSTI)

The effects of the growth temperature, composition, and elastic strains in separate layers on the segregation of antimony are studied experimentally for stressed SiGe structures grown by molecular beam epitaxy. It is established that the growth conditions and parameters of the structures exert an interrelated influence on the segregation of Sb: the degree of the influence of the composition and elastic stresses in the SiGe layers on Sb segregation depends on the growth temperature. It is shown that usage of a method previously proposed by us for the selective doping of silicon structures with consideration for the obtained dependences of Sb segregation on the growth conditions and parameters of the SiGe layers makes it possible to form SiGe structures selectively doped with antimony.

Drozdov, M. N.; Novikov, A. V.; Yurasov, D. V., E-mail: Inquisitor@ipm.sci.nnov.ru [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

2013-11-15T23:59:59.000Z

22

GaNAsP: An intermediate band semiconductor grown by gas-source molecular beam epitaxy  

SciTech Connect (OSTI)

Dilute nitride GaNAsP thin films were grown via a GaAsP metamorphic buffer on GaP(100) substrate with gas-source molecular beam epitaxy. The compositions of this III-V-V-V compound were determined by channeling Rutherford backscattering spectroscopy and nuclear reaction analysis. Photoreflectance shows two distinctive transitions from the valence band to the split conduction bands due to N incorporation. Photoluminescence and optical absorption show the fundamental bandgap of Ga(N)AsP is largely tailored by the small amount of N. The observed multiband characteristics and the bandgap tunability of GaNAsP are two merits that fit into the intermediate-band solar cell roadmap, and GaNAsP of high crystal quality provides a strong candidate for intermediate band solar cell materials.

Kuang, Y. J. [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States)] [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Yu, K. M.; Walukiewicz, W. [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kudrawiec, R. [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States) [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Institute of Physics, Wroclaw University of Technology, Wybrzeze, Wyspianskiego 27, 50-370 Wroclaw (Poland); Luce, A. V. [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States) [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Materials Science and Engineering, University of California, Berkeley, California 94720 (United States); Ting, M. [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States)] [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States); Tu, C. W. [Department of Electrical and Computer 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)

2013-03-18T23:59:59.000Z

23

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

SciTech Connect (OSTI)

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

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

2012-12-15T23:59:59.000Z

24

Interband transitions in molecular?beam?epitaxial Al x Ga1?x As/GaAs  

Science Journals Connector (OSTI)

Interband transition energies for Al x Ga1?x As layers grown by molecular?beam epitaxy(MBE) techniques have been determined using the electrolyte electroreflectance (EER) technique. The observed data fit quadratic relations for E 0 E 0+?0 E 1 and E 1+?1 to describe variations of energy with composition. Although the x values were not accurately known the internal consistency of the data is excellent. Given a single bowing parameter we show that accurate values of x can be determined. The EER technique can provide x values with an accuracy better than 0.02 and information on changes in x as small as 0.002. It is thus ideally suited for studying MBE materials.

J. L. Aubel; U. K. Reddy; S. Sundaram; W. T. Beard; James Comas

1985-01-01T23:59:59.000Z

25

Germanium diffusion during HfO{sub 2} growth on Ge by molecular beam epitaxy  

SciTech Connect (OSTI)

The authors study the Ge diffusion during HfO{sub 2} growth by molecular beam epitaxy on differently in situ prepared germanium substrates and at different growth temperatures. While HfO{sub 2} layers grown directly on Ge do not show any germanium contamination, oxygen rich interfacial layers such as GeO{sub x} or GeO{sub x}N{sub y} partly dissolve into the HfO{sub 2} layer, giving rise to high Ge contamination (from 1% to 10%). The use of nitridated interfacial layers does not prevent Ge diffusion into the HfO{sub 2} during the growth process because of the high oxygen content present in the nitridated germanium layer.

Ferrari, S.; Spiga, S.; Wiemer, C.; Fanciulli, M.; Dimoulas, A. [Laboratorio MDM-INFM-CNR, Via Olivetti, 2 Agrate Brianza, Milano 20041 (Italy); MBE Laboratory, Institute of Materials Science, DEMOKRITOS National Center for Scientific Research, 153 10 Athens (Greece)

2006-09-18T23:59:59.000Z

26

Infrared electroluminescence from GeSn heterojunction diodes grown by molecular beam epitaxy  

SciTech Connect (OSTI)

Infrared electroluminescence was observed from GeSn/Ge p-n heterojunction diodes with 8% Sn, grown by molecular beam epitaxy. The GeSn layers were boron doped, compressively strained, and pseudomorphic on Ge substrates. Spectral measurements indicated an emission peak at 0.57 eV, about 50 meV wide, increasing in intensity with applied pulsed current, and with reducing device temperatures. The total integrated emitted power from a single edge facet was 54 {mu}W at an applied peak current of 100 mA at 100 K. These results suggest that GeSn-based materials maybe useful for practical light emitting diodes operating in the infrared wavelength range near 2 {mu}m.

Gupta, Jay Prakash; Bhargava, Nupur; Kim, Sangcheol; Kolodzey, James [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States)] [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States); Adam, Thomas [Nanofab, University of Albany, SUNY, Albany, New York 12203 (United States)] [Nanofab, University of Albany, SUNY, Albany, New York 12203 (United States)

2013-06-24T23:59:59.000Z

27

Molecular-beam epitaxy growth of strontium thiogallate T. Yang, B. K. Wagner, M. Chaichimansour, W. Park, Z. L. Wang,a)  

E-Print Network [OSTI]

Molecular-beam epitaxy growth of strontium thiogallate T. Yang, B. K. Wagner, M. Chaichimansour, W-beam epitaxy growth and characterization of cerium doped strontium thiogallate SrGa2S4:Ce thin film phosphors growth of cerium doped strontium thiogallate on quartz substrates was first reported in 1994.3 Here we

Wang, Zhong L.

28

Molecular Beam Epitaxy on Gas Cluster Ion Beam Prepared GaSb Substrates: Towards Improved Surfaces and Interfaces  

SciTech Connect (OSTI)

A key problem in producing mid-infrared optoelectronic and low-power electronic devices in the GaSb material system is the lack of substrates with appropriate surfaces for epitaxial growth. Chemical mechanical polishing (CMP) of GaSb results in surface damage accompanied by tenacious oxides that do not easily desorb. To overcome this, we have developed a process using gas cluster ion beams (GCIB) to remove surface damage and produce engineered surface oxides. In this paper, we present surface modification results on GaSb substrates using O2-, CF4/O2-, and HBr-GCIB processes. X-ray photoelectron spectroscopy of GCIB produced surface layers showed the presence of mixed Ga- and Sb-oxides, with mostly Ga-oxides at the interface, desorbing at temperatures ranging 530°C to 560°C. Cross-sectional transmission electron microscopy of molecular beam epitaxy grown GaSb/AlGaSb layers showed that GCIB surfaces yielded smooth defect free substrate to epi transitions as compared to CMP surfaces. Furthermore, HBr-GCIB surfaces exhibited neither dislocation layers nor discernable interfaces, indicating complete oxide desorbtion prior to epigrowth on a clean single crystal template. Atomic force microscopy of GCIB epilayers exhibited smooth surfaces with characteristic step-terrace formations comprising monatomic steps and wide terraces. The HBr-GCIB process can be easily adapted to a large scale manufacturing process for epi-ready GaSb.

Krishnaswami, Kannan; Shivashankar, Vangala; Dauplaise, Helen; Allen, Lisa; Dallas, Gordon; Bakken, Daniel; Bliss, David; Goodhue, William

2008-04-01T23:59:59.000Z

29

Positron annihilation studies of defects in molecular beam epitaxy grown III-V layers  

SciTech Connect (OSTI)

A summary of recent positron annihilation experiments on molecular beam epitaxy (MBE) grown III-V layers is Presented. Variable energy positron beam measurements on Al{sub 0.32}Ga{sub 0.68}As undoped and Si doped have been completed. Positron trapping at a open volume defect in Al{sub 0.32}Ga{sub 0.68}:Si for temperatures from 300 to 25 K in the dark was observed. The positron trap was lost after 1.3 eV illumination at 25K. These results indicate an open volume defect is associated with the local structure of the deep donor state of the DX center. Stability of MBE GaAs to thermal annealing war, investigated over the temperature range of 230 to 700{degrees}C, Proximity wafer furnace anneals in flowing argon were used, Samples grown above 450{degrees}C were shown to be stable but for sample below this temperature an anneal induced vacancy related defect was produced for anneals between 400 and 500{degrees}C. The nature of the defect was shown to be different for material grown at 350 and 230{degrees}C. Activation energies of 2.5 eV to 2.3 eV were obtained from isochronal anneal experiments for samples grown at 350 and 230{degrees}C, respectively.

Umlor, M.T.; Keeble, D.J. [Michigan Technological Univ., Houghton, MI (United States). Dept. of Physics; Asoka-Kumar, P.; Lynn, K.G. [Brookhaven National Lab., Upton, NY (United States); Cooke, P.W. [Geo-Centers, Inc., Eatontown, NJ (United States). Fort Monmouth Operation

1994-08-01T23:59:59.000Z

30

Impact of substrate temperature on the incorporation of carbon-related defects and mechanism for semi-insulating behavior in GaN grown by molecular beam epitaxy  

E-Print Network [OSTI]

B 22, 1145 ?2004?. A. Armstrong, A. R. Arehart, D. Green, U.San Diego, 1992?. A. Armstrong, A. R. Arehart, and S. A.molecular beam epitaxy A. Armstrong Department of Electrical

Armstrong, A; Poblenz, C; Green, D S; Mishra, U K; Speck, J S; Ringel, S A

2006-01-01T23:59:59.000Z

31

Chlorine doping of cubic CdS and ZnS grown by compound source molecular-beam epitaxy  

Science Journals Connector (OSTI)

We report on the chlorine doping of ZnS and CdS grown by compound source molecular-beam epitaxy. The maximum free electron concentrations achieved were 1×1018 and 8×1019 cm?3, respectively. The conductivity of the cubic CdS epilayers turned out to be anisotropic with respect to the ?1 1 0? crystallographic directions due to an anisotropic lattice defect structure.

M Grün; A Storzum; M Hetterich; A Kamilli; W Send; Th Walter; C Klingshirn

1999-01-01T23:59:59.000Z

32

Growth of GaN on SiC(0001) by Molecular Beam Epitaxy C. D. LEE (a), ASHUTOSH SAGAR (a), R. M. FEENSTRA  

E-Print Network [OSTI]

]. Silicon carbide has a much better lattice match to GaN (3.4%), and has gained in popularity in recent years as a substrate for both molecular beam epitaxy (MBE) and metal-organic vapor phase epitaxy of Ga where a transition between streaky and spotty behavior occurs in the reflection high energy electron

Feenstra, Randall

33

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

SciTech Connect (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

34

Study of structural properties of cubic InN films on GaAs(001) substrates by molecular beam epitaxy and migration enhanced epitaxy  

SciTech Connect (OSTI)

InN epitaxial films with cubic phase were grown by rf-plasma-assisted molecular beam epitaxy (RF-MBE) on GaAs(001) substrates employing two methods: migration-enhanced epitaxy (MEE) and conventional MBE technique. The films were synthesized at different growth temperatures ranging from 490 to 550 Degree-Sign C, and different In beam fluxes (BEP{sub In}) ranging from 5.9 Multiplication-Sign 10{sup -7} to 9.7 Multiplication-Sign 10{sup -7} Torr. We found the optimum conditions for the nucleation of the cubic phase of the InN using a buffer composed of several thin layers, according to reflection high-energy electron diffraction (RHEED) patterns. Crystallographic analysis by high resolution X-ray diffraction (HR-XRD) and RHEED confirmed the growth of c-InN by the two methods. We achieved with the MEE method a higher crystal quality and higher cubic phase purity. The ratio of cubic to hexagonal components in InN films was estimated from the ratio of the integrated X-ray diffraction intensities of the cubic (002) and hexagonal (1011) planes measured by X-ray reciprocal space mapping (RSM). For MEE samples, the cubic phase of InN increases employing higher In beam fluxes and higher growth temperatures. We have obtained a cubic purity phase of 96.4% for a film grown at 510 Degree-Sign C by MEE.

Casallas-Moreno, Y. L.; Perez-Caro, M.; Gallardo-Hernandez, S.; Ramirez-Lopez, M.; Martinez-Velis, I.; Lopez-Lopez, M. [Physics Department, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 Mexico D.F. (Mexico)] [Physics Department, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 Mexico D.F. (Mexico); Escobosa-Echavarria, A. [Electric Engineering Department, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 Mexico D.F. (Mexico)] [Electric Engineering Department, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 Mexico D.F. (Mexico)

2013-06-07T23:59:59.000Z

35

Origin of Reflection High-Energy Electron-Diffraction Intensity Oscillations during Molecular-Beam Epitaxy: A Computational Modeling Approach  

Science Journals Connector (OSTI)

Temporal oscillations in the specular beam of reflection high-energy electron diffraction (RHEED) provide the primary method of monitoring growth by molecular-beam epitaxy. We develop a model to investigate the origin of these oscillations with which, by monitoring the step density of a growing sample, we are able to reproduce all of the principal features of recent RHEED measurements. Our work demonstrates the considerable advantages in adoption of simple monatomic growth models instead of the complex models used for studying the growth of compound semiconductors.

Shaun Clarke and Dimitri D. Vvedensky

1987-05-25T23:59:59.000Z

36

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

SciTech Connect (OSTI)

Atom probe tomography (APT) has been used to achieve three-dimensional characterization of a III-nitride laser diode (LD) structure grown by molecular beam epitaxy (MBE). Four APT data sets have been obtained, with fields of view up to 400 nm in depth and 120 nm in diameter. These data sets contain material from the InGaN quantum well (QW) active region, as well as the surrounding p- and n-doped waveguide and cladding layers, enabling comprehensive study of the structure and composition of the LD structure. Two regions of the same sample, with different average indium contents (18% and 16%) in the QW region, were studied. The APT data are shown to provide easy access to the p-type dopant levels, and the composition of a thin AlGaN barrier layer. Next, the distribution of indium within the InGaN QW was analyzed, to assess any possible inhomogeneity of the distribution of indium (''indium clustering''). No evidence for a statistically significant deviation from a random distribution was found, indicating that these MBE-grown InGaN QWs do not require indium clusters for carrier localization. However, the APT data show steps in the QW interfaces, leading to well-width fluctuations, which may act to localize carriers. Additionally, the unexpected presence of a small amount (x = 0.005) of indium in a layer grown intentionally as GaN was revealed. Finally, the same statistical method applied to the QW was used to show that the indium distribution within a thick InGaN waveguide layer in the n-doped region did not show any deviation from randomness.

Bennett, Samantha E.; Humphreys, Colin J.; Oliver, Rachel A. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Smeeton, Tim M.; Hooper, Stewart E.; Heffernan, Jonathan [Sharp Laboratories of Europe Limited, Edmund Halley Road, Oxford Science Park, Oxford, OX4 4GB (United Kingdom); Saxey, David W.; Smith, George D. W. [Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom)

2012-03-01T23:59:59.000Z

37

Ga-assisted catalyst-free growth mechanism of GaAs nanowires by molecular beam epitaxy  

Science Journals Connector (OSTI)

The mechanisms of Ga-assisted GaAs nanowires grown by molecular beam epitaxy are addressed. The axial and radial growth rates as a function of the Ga rate and As pressure indicate that on the opposite of what is observed in thin film epitaxy, the growth rate of the nanowires is arsenic limited. As a consequence, the axial growth rate of the wires can be controlled by the As4 pressure. Additionally, due to the small As4 pressure leading to nanowire growth, the deposition on the facets is very slow, leading to a much lower radial growth rate. Finally, we present a model that is able to accurately describe the presented observations and predicts a maximum length of nontapered nanowires of 40?m.

C. Colombo; D. Spirkoska; M. Frimmer; G. Abstreiter; A. Fontcuberta i Morral

2008-04-28T23:59:59.000Z

38

Topological insulator Bi 2 Se 3 thin films grown on double-layer graphene by molecular beam epitaxy  

Science Journals Connector (OSTI)

Atomically flat thin films of topological insulator Bi 2 Se 3 have been grown on double-layer graphene formed on 6H–SiC(0001) substrate by molecular beam epitaxy. By a combined study of reflection high energy electron diffraction and scanning tunneling microscopy we identified the Se-rich condition and temperature criterion for layer-by-layer growth of epitaxial Bi 2 Se 3 films. The as-grown films without doping exhibit a low defect density of 1.0 ± 0.2 × 10 11 / cm 2 and become a bulk insulator at a thickness of ten quintuple layers as revealed by in situ angle resolved photoemission spectroscopy measurement.

Can-Li Song; Yi-Lin Wang; Ye-Ping Jiang; Yi Zhang; Cui-Zu Chang; Lili Wang; Ke He; Xi Chen; Jin-Feng Jia; Yayu Wang; Zhong Fang; Xi Dai; Xin-Cheng Xie; Xiao-Liang Qi; Shou-Cheng Zhang; Qi-Kun Xue; Xucun Ma

2010-01-01T23:59:59.000Z

39

Ultra-high frequency photoconductivity decay in GaAs/Ge/GaAs double heterostructure grown by molecular beam epitaxy  

SciTech Connect (OSTI)

GaAs/Ge/GaAs double heterostructures (DHs) were grown in-situ using two separate molecular beam epitaxy chambers. High-resolution x-ray rocking curve demonstrates a high-quality GaAs/Ge/GaAs heterostructure by observing Pendelloesung oscillations. The kinetics of the carrier recombination in Ge/GaAs DHs were investigated using photoconductivity decay measurements by the incidence excitation from the front and back side of 15 nm GaAs/100 nm Ge/0.5 {mu}m GaAs/(100)GaAs substrate structure. High-minority carrier lifetimes of 1.06-1.17 {mu}s were measured when excited from the front or from the back of the Ge epitaxial layer, suggests equivalent interface quality of GaAs/Ge and Ge/GaAs. Wavelength-dependent minority carrier recombination properties are explained by the wavelength-dependent absorption coefficient of Ge.

Hudait, M. K.; Zhu, Y. [Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Johnston, S. W. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)] [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Maurya, D.; Priya, S. [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Umbel, R. [Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)

2013-03-04T23:59:59.000Z

40

Peculiarly strong room-temperature ferromagnetism from low Mn-doping in ZnO grown by molecular beam epitaxy  

SciTech Connect (OSTI)

Strong room-temperature ferromagnetism is demonstrated in single crystalline Mn-doped ZnO thin films grown by molecular beam epitaxy. Very low Mn doping concentration is investigated, and the measured magnetic moment is much larger than what is expected for an isolated ion based on Hund's rules. The ferromagnetic behavior evolves with Mn concentration. Both magnetic anisotropy and anomalous Hall effect confirm the intrinsic nature of ferromagnetism. While the Mn dopant plays a crucial role, another entity in the system is needed to explain the observed large magnetic moments.

Zuo Zheng; Morshed, Muhammad; Liu Jianlin [Quantum Structures Laboratory, Department of Electrical Engineering, University of California at Riverside, Riverside, California 92521 (United States); Beyermann, W. P. [Department of Physics and Astronomy, University of California at 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, FL 32310-3706 (United States)

2013-03-15T23:59:59.000Z

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.


41

Chirped-pulse manipulated carrier dynamics in low-temperature molecular-beam-epitaxy grown GaAs  

SciTech Connect (OSTI)

Chirped pulse controlled carrier dynamics in low-temperature molecular-beam-epitaxy grown GaAs are investigated by degenerate pump-probe technique. Varying the chirped condition of excited pulse from negative to positive increases the carrier relaxation time so as to modify the dispersion and reshape current pulse in time domain. The spectral dependence of carrier dynamics is analytically derived and explained by Shockley-Read Hall model. This observation enables the new feasibility of controlling carrier dynamics in ultrafast optical devices via the chirped pulse excitations.

Lee, Chao-Kuei, E-mail: chuckcklee@yahoo.com [Department of Photonics, National Sun-Yat-Sen University, Kaohsiung 80400, Taiwan (China); Lin, Yuan-Yao [Department of Electrical Engineering, Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30010, Taiwan (China); Lin, Sung-Hui [Department of Photonics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Lin, Gong-Ru [Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Roosevelt Road, Sec. 4, Taipei 10617, Taiwan (China); Pan, Ci-Ling [Department of Photonics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Department of Physics, National Tsing Hwa University, Hsinchu 30010, Taiwan (China)

2014-04-28T23:59:59.000Z

42

Elastic effects and phase segregation during the growth of thin alloy layers by molecular-beam epitaxy  

Science Journals Connector (OSTI)

We explore the effects of stress and strain on the composition modulations seen during the growth of thin solid films by molecular-beam epitaxy when phase separation is the driving mechanism for the concentration inhomogeneity. A top view of the growing thin film shows lamellar and hexagonal patterns of phase-separated domains, the elastic effects being directly responsible for the appearance of the hexagonal order. We find that in the lamellar regime, elastically deformed lamellae are separated by undeformed interfaces, while in the droplet phase, the soft component is deformed and wraps the hard component. We also discuss the effects of crystal anisotropy in our system.

François Léonard and Rashmi C. Desai

1997-08-15T23:59:59.000Z

43

Inhomogeneous Si-doping of gold-seeded InAs nanowires grown by molecular beam epitaxy  

SciTech Connect (OSTI)

We have investigated in situ Si doping of InAs nanowires grown by molecular beam epitaxy from gold seeds. The effectiveness of n-type doping is confirmed by electrical measurements showing an increase of the electron density with the Si flux. We also observe an increase of the electron density along the nanowires from the tip to the base, attributed to the dopant incorporation on the nanowire facets whereas no detectable incorporation occurs through the seed. Furthermore, the Si incorporation strongly influences the lateral growth of the nanowires without giving rise to significant tapering, revealing the complex interplay between axial and lateral growth.

Rolland, Chloe; Coinon, Christophe; Wallart, Xavier; Leturcq, Renaud [Institute of Electronics Microelectronics and Nanotechnology, UMR CNRS 8520, ISEN Department, Avenue Poincare, CS60069, 59652 Villeneuve d'Ascq Cedex (France)] [Institute of Electronics Microelectronics and Nanotechnology, UMR CNRS 8520, ISEN Department, Avenue Poincare, CS60069, 59652 Villeneuve d'Ascq Cedex (France); Caroff, Philippe [Institute of Electronics Microelectronics and Nanotechnology, UMR CNRS 8520, ISEN Department, Avenue Poincare, CS60069, 59652 Villeneuve d'Ascq Cedex (France) [Institute of Electronics Microelectronics and Nanotechnology, UMR CNRS 8520, ISEN Department, Avenue Poincare, CS60069, 59652 Villeneuve d'Ascq Cedex (France); Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia)

2013-06-03T23:59:59.000Z

44

Physical properties and band structure of reactive molecular beam epitaxy grown oxygen engineered HfO{sub 2{+-}x}  

SciTech Connect (OSTI)

We have conducted a detailed thin film growth structure of oxygen engineered monoclinic HfO{sub 2{+-}x} grown by reactive molecular beam epitaxy. The oxidation conditions induce a switching between (111) and (002) texture of hafnium oxide. The band gap of oxygen deficient hafnia decreases with increasing amount of oxygen vacancies by more than 1 eV. For high oxygen vacancy concentrations, defect bands form inside the band gap that induce optical transitions and p-type conductivity. The resistivity changes by several orders of magnitude as a function of oxidation conditions. Oxygen vacancies do not give rise to ferromagnetic behavior.

Hildebrandt, Erwin; Kurian, Jose; Alff, Lambert [Institute of Materials Science, Technische Universitaet Darmstadt, 64287 Darmstadt (Germany)

2012-12-01T23:59:59.000Z

45

Optical properties of strain-free AlN nanowires grown by molecular beam epitaxy on Si substrates  

SciTech Connect (OSTI)

The optical properties of catalyst-free AlN nanowires grown on Si substrates by molecular beam epitaxy were investigated. Such nanowires are nearly free of strain, with strong free exciton emission measured at room temperature. The photoluminescence intensity is significantly enhanced, compared to previously reported AlN epilayer. Moreover, the presence of phonon replicas with an energy separation of ?100?meV was identified to be associated with the surface-optical phonon rather than the commonly reported longitudinal-optical phonon, which is further supported by the micro-Raman scattering experiments.

Wang, Q.; Zhao, S.; Connie, A. T.; Shih, I.; Mi, Z., E-mail: zetian.mi@mcgill.ca [Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, Quebec H3A 0E9 (Canada); Gonzalez, T.; Andrews, M. P. [Department of Chemistry, McGill University, 801 Sherbrooke St West, Montreal, Quebec H3A 0B8 (Canada); Du, X. Z.; Lin, J. Y.; Jiang, H. X. [Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)

2014-06-02T23:59:59.000Z

46

Self-corrected Sensors Based On Atomic Absorption Spectroscopy For Atom Flux Measurements In Molecular Beam Epitaxy  

SciTech Connect (OSTI)

A high sensitivity atom flux sensor based on atomic absorption spectroscopy has been designed and implemented to control electron beam evaporators and effusion cells in a molecular beam epitaxy system. Using a high-resolution spectrometer and a two-dimensional charge coupled device (CCD) detector in a double-beam configuration, we employ a non-resonant line or a resonant line with lower absorbance from the same hollow cathode lamp as the reference for nearly perfect background correction and baseline drift removal. This setup also significantly shortens the warm-up time needed compared to other sensor technologies and drastically reduces the noise coming from the surrounding environment. In addition, the high-resolution spectrometer allows the most sensitive resonant line to be isolated and used to provide excellent signal-to-noise ratio.

Du, Yingge; Droubay, Timothy C.; Liyu, Andrey V.; Li, Guosheng; Chambers, Scott A.

2014-04-24T23:59:59.000Z

47

Photoluminescence from GaAs nanodisks fabricated by using combination of neutral beam etching and atomic hydrogen-assisted molecular beam epitaxy regrowth  

SciTech Connect (OSTI)

We have fabricated GaAs nanodisk (ND) structures by using a combination of neutral beam etching process and atomic hydrogen-assisted molecular beam epitaxy regrowth. We have observed clear photoluminescence (PL) emissions from GaAs NDs. The peak energy showed a blueshift due to the quantum confinement in three spatial dimensions, and it agreed with the theoretically estimated transition energy. The PL results also showed that the cap-layer disks act as radiative recombination centers. We have confirmed that the PL emission originates from the GaAs NDs, and our approach is effective for the fabrication of high quality ND structures.

Kaizu, Toshiyuki; Okada, Yoshitaka [Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Japan Science and Technology Agency, CREST, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); Tamura, Yosuke; Igarashi, Makoto; Hu, Weiguo; Tsukamoto, Rikako [Japan Science and Technology Agency, CREST, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yamashita, Ichiro [Japan Science and Technology Agency, CREST, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Samukawa, Seiji [Japan Science and Technology Agency, CREST, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); WPI Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2012-09-10T23:59:59.000Z

48

Non-adiabatic ab initio molecular dynamics of supersonic beam epitaxy of silicon carbide at room temperature  

SciTech Connect (OSTI)

In this work, we investigate the processes leading to the room-temperature growth of silicon carbide thin films by supersonic molecular beam epitaxy technique. We present experimental data showing that the collision of fullerene on a silicon surface induces strong chemical-physical perturbations and, for sufficient velocity, disruption of molecular bonds, and cage breaking with formation of nanostructures with different stoichiometric character. We show that in these out-of-equilibrium conditions, it is necessary to go beyond the standard implementations of density functional theory, as ab initio methods based on the Born-Oppenheimer approximation fail to capture the excited-state dynamics. In particular, we analyse the Si-C{sub 60} collision within the non-adiabatic nuclear dynamics framework, where stochastic hops occur between adiabatic surfaces calculated with time-dependent density functional theory. This theoretical description of the C{sub 60} impact on the Si surface is in good agreement with our experimental findings.

Taioli, Simone [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Department of Physics, University of Trento, Trento (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Perugia (Italy); Department of Chemistry, University of Bologna, Bologna (Italy); Garberoglio, Giovanni [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Simonucci, Stefano [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Perugia (Italy); Department of Physics, University of Camerino, Camerino (Italy); Beccara, Silvio a [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Department of Physics, University of Trento, Trento (Italy); Aversa, Lucrezia [Institute of Materials for Electronics and Magnetism, IMEM-CNR, Trento (Italy); Nardi, Marco [Institute of Materials for Electronics and Magnetism, IMEM-CNR, Trento (Italy); Institut fuer Physik, Humboldt-Universitaet zu Berlin, Berlin (Germany); Verucchi, Roberto [Institute of Materials for Electronics and Magnetism, FBK-CNR, Trento (Italy); Iannotta, Salvatore [Institute of Materials for Electronics and Magnetism, IMEM-CNR, Parma (Italy); Dapor, Maurizio [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Department of Materials Engineering and Industrial Technologies, University of Trento, Trento (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Padova (Italy); and others

2013-01-28T23:59:59.000Z

49

Energy band alignment of atomic layer deposited HfO{sub 2} on epitaxial (110)Ge grown by molecular beam epitaxy  

SciTech Connect (OSTI)

The band alignment properties of atomic layer HfO{sub 2} film deposited on epitaxial (110)Ge, grown by molecular beam epitaxy, was investigated using x-ray photoelectron spectroscopy. The cross-sectional transmission electron microscopy exhibited a sharp interface between the (110)Ge epilayer and the HfO{sub 2} film. The measured valence band offset value of HfO{sub 2} relative to (110)Ge was 2.28 {+-} 0.05 eV. The extracted conduction band offset value was 2.66 {+-} 0.1 eV using the bandgaps of HfO{sub 2} of 5.61 eV and Ge bandgap of 0.67 eV. These band offset parameters and the interface chemical properties of HfO{sub 2}/(110)Ge system are of tremendous importance for the design of future high hole mobility and low-power Ge-based metal-oxide transistor devices.

Hudait, M. K.; Zhu, Y. [Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Maurya, D.; Priya, S. [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States)

2013-03-04T23:59:59.000Z

50

Investigation of the evolution of single domain ,,111...B CdTe films by molecular beam epitaxy on miscut ,,001...Si substrate  

E-Print Network [OSTI]

Investigation of the evolution of single domain ,,111...B CdTe films by molecular beam epitaxy; accepted for publication 22 July 1998 A comprehensive view of the microstructure of 111 B CdTe films grown and scanning transmission electron microscopy. It is found that in the initial growth stage, CdTe nucleates

Pennycook, Steve

51

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

SciTech Connect (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 (<0.09 {Omega} mm) were obtained, with a minimum R{sub C} of 0.035 {Omega} mm on a sample with a room temperature carrier concentration of {approx}5 Multiplication-Sign 10{sup 19} cm{sup -3}. Based on the systematic study, the role of R{sub C} and R{sub sh} is discussed in the context of regrown n{sup +} GaN ohmic contacts for GaN based high 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

52

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

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

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

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

2011-01-07T23:59:59.000Z

53

Stoichiometric, nonstoichiometric, and locally nonstoichiometric SrTiO{sub 3} films grown by molecular beam epitaxy  

SciTech Connect (OSTI)

SrTiO{sub 3} films were grown by reactive molecular beam epitaxy to have varying degrees of both global and local cationic nonstoichiometries (with stoichiometry defined as a 1:1 ratio of Sr:Ti). Slight global excesses of Sr and Ti resulted in two-fold reconstructions in the reflection high-energy electron diffraction patterns along the [110] and [100] azimuths, respectively. Larger global nonstoichiometries (2:1 and 1:2 ratios) were also accommodated into the film's crystalline structure and affected the long-range crystalline order as observed in the x-ray diffraction patterns, both of which were related to the parent perovskite pattern. Local nonstoichiometries were introduced by depositing multiple monolayers (MLs) (from 2 to 33) of SrO and TiO{sub 2} in an alternating fashion, while maintaining the global SrTiO{sub 3} stoichiometry. These layered structures of SrO and TiO{sub 2} blocks inter-reacted during growth to form highly crystalline epitaxial SrTiO{sub 3}. Films grown in this manner with blocks thicker than 8 MLs were fully relaxed and, when the block thicknesses ranged between 8 and 10 MLs, the full widths at half maxima of 2{theta} peaks were narrower than the standard SrTiO{sub 3} films having blocks 1 ML thick.

Fisher, P.; Du, H.; Skowronski, M.; Salvador, P. A. [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Maksimov, O. [Electro-Optics Center, Pennsylvania State University, Freeport, Pennsylvania 16229 (United States); Weng, X. [Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2008-01-01T23:59:59.000Z

54

Oxygen vacancy induced photoluminescence and ferromagnetism in SrTiO{sub 3} thin films by molecular beam epitaxy  

SciTech Connect (OSTI)

SrTiO{sub 3} thin films were epitaxially grown on (100) SrTiO{sub 3} substrates using molecular beam epitaxy. The temperature for growth of the films was optimized, which was indicated by x-ray diffraction and further confirmed by microstructural characterization. Photoluminescence spectra show that oxygen-vacancy contributes to red and blue luminescence of oxygen-deficient post-annealed films, and a red shift was observed in blue region. On the other hand, ferromagnetism in film form SrTiO{sub 3} was observed from 5 K to 400 K and could be further enhanced with decreasing oxygen plasma partial pressure in annealing processes, which might be explained by the theory involving d{sup 0} magnetism related to oxygen-vacancy. From the cooperative investigations of optical and magnetic properties, we conclude that intrinsic defects, especially oxygen-vacancy, can induce and enhance luminescence and magnetism in SrTiO{sub 3} films.

Xu, Wenfei; Yang, Jing; Bai, Wei; Tang, Kai; Zhang, Yuanyuan [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China)] [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China); Tang, Xiaodong [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China) [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China); Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Rd., Shanghai 200050 (China)

2013-10-21T23:59:59.000Z

55

Characterization of high quality InN grown on production-style plasma assisted molecular beam epitaxy system  

SciTech Connect (OSTI)

In this work, the authors report step-flow growth mode of InN on [0001] oriented GaN templates, using a production-style molecular beam epitaxy system, Veeco GEN200 registered , equipped with a plasma source. Using adaptive growth conditions, they have obtained a surface morphology that exhibits the step-flow features. The root mean squared roughness over an area of 5x5 {mu}m{sup 2} is 1.4 nm with monolayer height terrace steps (0.281 nm), based on atomic force microscopy. It has been found that the presence of In droplets leads to defective surface morphology. From x-ray diffraction, they estimate edge and screw dislocation densities. The former is dominant over the latter. Micro-Raman spectra reveal narrow E{sub 2}{sup 2} phonon lines consistent with excellent crystalline quality of the epitaxial layers. The Hall mobility of 1 {mu}m thick InN layers, grown in step-flow mode, is slightly higher than 1400 cm{sup 2}/V s, while for other growth conditions yielding a smooth surface with no well-defined steps, mobility as high as 1904 cm{sup 2}/V s at room temperature has been measured. The samples exhibit high intensity photoluminescence (PL) with a corresponding band edge that shifts with free carrier concentration. For the lowest carrier concentration of 5.6x10{sup 17} cm{sup -3}, they observe PL emission at {approx}0.64 eV.

Gherasoiu, I.; O'Steen, M.; Bird, T.; Gotthold, D.; Chandolu, A.; Song, D. Y.; Xu, S. X.; Holtz, M.; Nikishin, S. A.; Schaff, W. J. [Veeco Instruments Inc., MBE Operations, 4900 Constellation Drive, St. Paul, Minnesota 55127 (United States); Nano Tech Center, Texas Tech University, Lubbock, Texas 79409 (United States); Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14583 (United States)

2008-05-15T23:59:59.000Z

56

Direct imaging of InSb (110)-(1x1) surface grown by molecular beam epitaxy  

SciTech Connect (OSTI)

High-resolution transmission electron microscopy under a profile imaging condition (HR-profile TEM) was employed to determine the structural model for the InSb(110)-(1x1) relaxation surface grown by molecular beam epitaxy (MBE). HR-profile TEM analyses indicate that the chevron model, which is widely accepted for zinc-blende-type III-V(110)-(1x1) surfaces prepared by cleavage, is also applicable to the InSb(110)-(1x1) surface prepared under an Sb-rich MBE condition. The assignment of atomic species (In or Sb) of InSb(110)-(1x1) surfaces was confirmed based on a HR-profile TEM image that captures the connected facets of InSb(110)-(1x1) and InSb(111)B-(2x2). On the basis of the well-known atomic species of InSb(111)B-(2x2), the atomic species of the InSb(110)-(1x1) surface were deduced straightforwardly: the atoms shifted upward and downward at the topmost layer of the InSb(110)-(1x1) surface are Sb and In, respectively. The atomic arrangements of the InSb(110)-(1x1)-InSb(111)B-(2x2) facet determined by HR-profile TEM may represent the atomic arrangements of zinc-blende-type III-V(331)B surfaces.

Mishima, T. D. [Homer L. Dodge Department of Physics and Astronomy, and Center for Semiconductor Physics in Nanostructures, University of Oklahoma, Norman, Oklahoma 73019 (United States)

2011-10-01T23:59:59.000Z

57

Electroreflectance study of effects of indium segregation in molecular-beam-epitaxy-grown InGaAs/GaAs  

Science Journals Connector (OSTI)

Electrolyte electroreflectance (EER) experiments were performed on In 0.22 Ga 0.78 As/GaAs single quantum wells grown by the conventional molecular-beam-epitaxy (MBE) shutter operation and also by modified MBE shutter operation intended to form more compositionally abrupt normal and inverted interfaces. The latter included controlled thermal desorption of the surface segregated In at the InGaAs layer surface (flash off) and the deposition of In at the InGaAs/GaAs interface to eliminate compositional broadening (predeposition). The fundamental energy gap and subband transitions were determined experimentally and compared with an accurate calculation of the potential well problem including strain. These results confirmed the segregation of In atoms near the interface. The segregation was maximum in the conventional (normal) MBE sample and least with the modified growth incorporating predeposition and flash off as expected. The segregated atoms are observed to act as dopants and form junctions near the InGaAs/GaAs interface. This study shows that EER can be used as an effective tool for studying the segregation process in MBE growth.

K. Chattopadhyay; J. Aubel; S. Sundaram; J. E. Ehret; R. Kaspi; Keith R. Evans

1997-01-01T23:59:59.000Z

58

Oxygen plasma power dependence on ZnO grown on porous silicon substrates by plasma-assisted molecular beam epitaxy  

SciTech Connect (OSTI)

ZnO thin films were deposited on porous silicon by plasma-assisted molecular beam epitaxy using different radio frequency power settings. Optical emission spectrometry was applied to study the characteristics of the oxygen plasma, and the effects of the radio frequency power on the properties of the ZnO thin films were evaluated by X-ray diffraction, scanning electron microscopy, and photoluminescence. The grain sizes for radio frequency powers of 100, 200, and 300 W were 46, 48, and 62 nm, respectively. In addition, the photoluminescence intensities of the ultraviolet and the visible range increased at 300 W, because the density of the atomic oxygen transitions increased. The quality of the ZnO thin films was enhanced, but the deep-level emission peaks increased with increasing radio frequency power. The structural and optical properties of the ZnO thin films were improved at the radio frequency power of 300 W. Moreover, the optical properties of the ZnO thin films were improved with porous silicon, instead of Si.

Nam, Giwoong [Department of Nano Engineering, Inje University, Gimhae, Gyungnam 621-749 (Korea, Republic of)] [Department of Nano Engineering, Inje University, Gimhae, Gyungnam 621-749 (Korea, Republic of); Kim, Min Su [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Gimhae, Gyungnam 621-749 (Korea, Republic of)] [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Gimhae, Gyungnam 621-749 (Korea, Republic of); Kim, Do Yeob [Holcombe Department of Electrical and Computer Engineering, Center for Optical Materials Science and Engineering Technologies, Clemson University, Clemson, SC 29634 (United States)] [Holcombe Department of Electrical and Computer Engineering, Center for Optical Materials Science and Engineering Technologies, Clemson University, Clemson, SC 29634 (United States); Yim, Kwang Gug [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Gimhae, Gyungnam 621-749 (Korea, Republic of)] [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Gimhae, Gyungnam 621-749 (Korea, Republic of); Kim, Soaram [Department of Nano Engineering, Inje University, Gimhae, Gyungnam 621-749 (Korea, Republic of)] [Department of Nano Engineering, Inje University, Gimhae, Gyungnam 621-749 (Korea, Republic of); Kim, Sung-O. [Holcombe Department of Electrical and Computer Engineering, Center for Optical Materials Science and Engineering Technologies, Clemson University, Clemson, SC 29634 (United States)] [Holcombe Department of Electrical and Computer Engineering, Center for Optical Materials Science and Engineering Technologies, Clemson University, Clemson, SC 29634 (United States); Lee, Dong-Yul [Epi R and D Team, Samsung LED Co. Ltd., Suwon, Gyeonggi-do 443-373 (Korea, Republic of)] [Epi R and D Team, Samsung LED Co. Ltd., Suwon, Gyeonggi-do 443-373 (Korea, Republic of); Leem, Jae-Young, E-mail: jyleem@inje.ac.kr [Department of Nano Engineering, Inje University, Gimhae, Gyungnam 621-749 (Korea, Republic of) [Department of Nano Engineering, Inje University, Gimhae, Gyungnam 621-749 (Korea, Republic of); Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Gimhae, Gyungnam 621-749 (Korea, Republic of)

2012-10-15T23:59:59.000Z

59

Control of tensile strain and interdiffusion in Ge/Si(001) epilayers grown by molecular-beam epitaxy  

SciTech Connect (OSTI)

Tensile-strained and n-doped Ge has emerged as a potential candidate for the realization of optoelectronic devices that are compatible with the mainstream silicon technology. Tensile-strained Ge/Si epilayers can be obtained by using the difference of thermal expansion coefficients between Ge and Si. We have combined various surface, structural, and compositional characterizations to investigate the growth mode and the strain state in Ge/Si epilayers grown by molecular-beam epitaxy. The Ge growth was carried out using a two-step approach: a low-temperature growth to produce relaxed and smooth buffer layers, which is followed by a high-temperature growth to get high quality Ge layers. The existence of a substrate temperature window from 260 to 300 °C is evidenced, which allows to completely suppress the Ge/Si Stranski-Krastanov growth. As a consequence of the high temperature growth, a tensile strain lying in the range of 0.22%–0.24% is obtained. Concerning the effect of thermal annealing, it is shown that cyclic annealing may allow increasing the tensile strain up to 0.30%. Finally, we propose an approach to use carbon adsorption to suppress Si/Ge interdiffusion, which represents one of the main obstacles to overcome in order to realize pure Ge-based optoelectronic devices.

Luong, T. K. P.; Dau, M. T.; Zrir, M. A.; Le Thanh, V.; Petit, M. [Aix-Marseille Université, CNRS CINaM-UMR 7325, F-13288 Marseille Cedex 09 (France)] [Aix-Marseille Université, CNRS CINaM-UMR 7325, F-13288 Marseille Cedex 09 (France); Stoffel, M.; Rinnert, H. [Université de Lorraine, Institut Jean Lamour, CNRS UMR 7198, Nancy-Université, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex (France)] [Université de Lorraine, Institut Jean Lamour, CNRS UMR 7198, Nancy-Université, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex (France); Ghrib, A.; El Kurdi, M.; Boucaud, P. [Institut d'Electronique Fondamentale, CNRS UMR 8622, Université Paris-Sud, Ba-carett. 220, 91405 Orsay (France)] [Institut d'Electronique Fondamentale, CNRS UMR 8622, Université Paris-Sud, Ba-carett. 220, 91405 Orsay (France); Murota, J. [Research Institute of Electrical Communications, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)] [Research Institute of Electrical Communications, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2013-08-28T23:59:59.000Z

60

Localized Si enrichment in coherent self-assembled Ge islands grown by molecular beam epitaxy on (001)Si single crystal  

SciTech Connect (OSTI)

Transmission electron microscopy (TEM), atomic force microscopy, and Rutherford backscattering spectrometry (RBS) have been used to investigate the morphology, structure, and composition of self-assembled Ge islands grown on Si (001) substrates by molecular beam epitaxy (MBE) at different temperatures. Increasing the temperature from 550 Degree-Sign C to 700 Degree-Sign C causes progressive size and shape uniformity, accompanied by enhanced Si-Ge intermixing within the islands and their wetting layer. Elemental maps obtained by energy filtered-TEM (EF-TEM) clearly show pronounced Si concentration not only in correspondence of island base perimeters, but also along their curved surface boundaries. This phenomenon is strengthened by an increase of the growth temperature, being practically negligible at 550 Degree-Sign C, while very remarkable already at 650 Degree-Sign C. The resulting island shape is affected, since this localized Si enrichment not only provides strain relief near their highly stressed base perimeters but it also influences the cluster surface energy by effective alloying, so as to form Si-enriched SiGe interfaces. Further increase to 700 Degree-Sign C causes a shape transition where more homogenous Si-Ge concentration profiles are observed. The crucial role played by local 'flattened' alloyed clusters, similar to truncated pyramids with larger bases and enhanced Si enrichment at coherently stressed interfaces, has been further clarified by EF-TEM analysis of a multi-layered Ge/Si structure containing stacked Ge islands grown at 650 Degree-Sign C. Sharp accumulation of Si has been here observed not only in proximity of the uncapped island surface in the topmost layer but also at the buried Ge/Si interfaces and even in the core of such capped Ge islands.

Valvo, M. [Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 64, I-95127 Catania (Italy); Bongiorno, C.; Giannazzo, F. [IMM-CNR, VIII strada 5, 95121 Catania (Italy); Terrasi, A. [Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 64, I-95127 Catania (Italy); MATIS IMM-CNR UOS Catania (Universita), via S. Sofia 64, 95123 Catania (Italy)

2013-01-21T23:59:59.000Z

Note: This page contains sample records for the topic "molecular beam epitaxy" from the National Library of EnergyBeta (NLEBeta).
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61

Ion-beam-induced epitaxial vapor-phase growth: A molecular-dynamics study  

Science Journals Connector (OSTI)

Low-energy ions which bombard a vapor-deposited film of low adatom mobility during growth mobilize surface atoms in the vicinity of the ion impact, causing a modification in the evolving microstructure. In a two-dimensional molecular-dynamics simulation where inert-gas ions strike a growing film of Lennard-Jones particles, it is demonstrated that ion bombardment during growth causes the filling of voids quenched in during vapor condensation and induces homoepitaxial growth. The dependence of film density and degree of homoepitaxial growth on the ion-to-vapor arrival rate ratio and ion energy is studied in detail.

Karl-Heinz Müller

1987-05-15T23:59:59.000Z

62

Structural properties of SrO thin films grown by molecular beam epitaxy on LaAlO{sub 3} substrates  

SciTech Connect (OSTI)

SrO films were grown on LaAlO{sub 3} substrates by molecular beam epitaxy and characterized using reflection high-energy electron diffraction (RHEED) and x-ray diffraction (XRD). The evolution of the RHEED pattern is discussed as a function of film thickness. 500 A thick SrO films were relaxed and exhibited RHEED patterns indicative of an atomically smooth surface having uniform terrace heights. Films had the epitaxial relationship (001){sub SrO}(parallel sign)(001){sub LaAlO{sub 3}}; [010]{sub SrO}(parallel sign)[110]{sub LaAlO{sub 3}}. This 45 deg. in-plane rotation minimizes mismatch and leads to films of high crystalline quality, as verified by Kikuchi lines in the RHEED patterns and narrow rocking curves of the (002) XRD peak.

Maksimov, O.; Heydemann, V. D.; Fisher, P.; Skowronski, M.; Salvador, P. A. [Electro-Optics Center, Pennsylvania State University, Freeport, Pennsylvania 16229 (United States); Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

2006-12-25T23:59:59.000Z

63

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

SciTech Connect (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

64

Magneto-transport properties of InAs nanowires laterally-grown by selective area molecular beam epitaxy on GaAs (110) masked substrates  

SciTech Connect (OSTI)

We prepared InAs nanowires (NWs) by lateral growth on GaAs (110) masked substrates in molecular beam epitaxy. We measured magneto-transport properties of the InAs NWs. In spite of parallel-NW multi-channels, we observed fluctuating magneto-conductance. From the fluctuation, we evaluated phase coherence length as a function of measurement temperature, and found decrease in the length with increase in the temperature. We also evaluate phase coherence length as a function of gate voltage.

Akabori, M.; Yamada, S. [Center for Nano-Materials and Technology, Japan Advanced Institute of Science and Technology, 1-1, Asahidai, Nomi, Ishikawa 923-1292 (Japan)

2013-12-04T23:59:59.000Z

65

Molecular Beam Epitaxy | EMSL  

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

temperature monitored by a two-color pyrometer andor thermocouple In situ optical (atomic absorption) and reflection high-energy electron diffraction (RHEED) probes for...

66

A Comparison of Magnesium and Beryllium Acceptors in GaN Grown by rf-Plasma Assisted Molecular Beam Epitaxy  

E-Print Network [OSTI]

A Comparison of Magnesium and Beryllium Acceptors in GaN Grown by rf-Plasma Assisted Molecular Beam Evans and Associates, Sunnyvale, CA 94086 ABSTRACT Step-doped structures of both magnesium and beryllium activation energy of approximately 100 meV. INTRODUCTION While magnesium is currently the most

Myers, Tom

67

Structural characterization of SiGe/Si single wells grown by disilane and solid-Ge molecular beam epitaxy with varied disilane cracking temperature  

Science Journals Connector (OSTI)

Structural properties of SiGe/Si single wells are studied by double-crystal X-ray diffraction. Four SiGe/Si single wells have been grown on Si (0 0 1) at 750°C by disilane and solid-Ge molecular beam epitaxy with varied disilane cracking temperature. Using dynamic theory, together with kinematic theory and the specific growth procedure adopted, structural parameters in the multilayer structure are determined precisely. The results are compared with those obtained from PL and XTEM as well as AES measurements. It is found that disilane adsorption is dependent on cracking temperature as well as Ge incorporation. Disilane adsorption is increased by cracking disilane while it decreased with Ge incorporation

J.P. Liu; M.Y. Kong; D.D. Huang; J.P. Li; D.Z. Sun

1998-01-01T23:59:59.000Z

68

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 (OSTI)

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

69

Electroluminescence at 1.54 {mu}m in Si:Er/Si structures grown by sublimation molecular-beam epitaxy  

SciTech Connect (OSTI)

In Si:Er/Si diode structures grown by sublimation molecular-beam epitaxy in a vacuum with a pressure of {approx}10{sup -7} mbar at temperatures 520-580 deg. C, the intensity of room-temperature electroluminescence at 1.54 {mu}m is studied as a function of the concentration and distribution of erbium and donor impurities in the space-charge region (SCR) and the SCR width. Methods for obtaining electroluminescence in diodes with a wide (0.1-1 {mu}m) SCR are developed. The mean free path of electrons with respect to their interaction with Er centers and the threshold energy a free electron needs in order to excite an Er-shell electron are determined. The values of electric-field strength corresponding to breakdown in silicon p-i-n diodes with and without Er doping are obtained experimentally. A model describing the interaction of hot electrons with Er centers is suggested.

Kuznetsov, V. P. [Nizhni Novgorod State University, Physicotechnical Research Institute (Russian Federation)], E-mail: Kuznetsov_VP@mail.ru; Remizov, D. Yu. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Shabanov, V. N.; Rubtsova, R. A. [Nizhni Novgorod State University, Physicotechnical Research Institute (Russian Federation); Stepikhova, M. V.; Kryzhov, D. I. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Shushunov, A. N.; Belova, O. V. [Nizhni Novgorod State University, Physicotechnical Research Institute (Russian Federation); Krasil'nik, Z. F. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Maksimov, G. A. [Nizhni Novgorod State University, Physicotechnical Research Institute (Russian Federation)

2006-07-15T23:59:59.000Z

70

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

SciTech Connect (OSTI)

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

71

A series of layered intergrowth phases grown by molecular beam epitaxy: Sr{sub m}TiO{sub 2+m}(m=1-5)  

SciTech Connect (OSTI)

Sr{sub m}TiO{sub 2+m} phases having one TiO{sub 2} layer sandwiched between m SrO layers were grown using molecular beam epitaxy. The out-of-plane (in-plane) lattice parameters determined by x-ray diffraction were c(a)=9.14 A (3.78 A), 23.55 A (3.75 A), and 14.60 A (3.75 A) for Sr{sub 3}TiO{sub 5}, Sr{sub 4}TiO{sub 6}, and Sr{sub 5}TiO{sub 7}, respectively. Both lattice parameters change abruptly on going from the m=2 Ruddlesden-Popper phase to m=3 phase, indicating a significant change in the bond lengths (or strain states) on transitioning from the known members to the higher order members of this structural family. Electron microscopy confirmed the artificially layered structures.

Fisher, P.; Wang, S.; Skowronski, M.; Salvador, P. A.; Snyder, M.; Maksimov, O. [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Electro-Optics Center, Pennsylvania State University, Freeport, Pennsylvania 16229 (United States)

2007-12-17T23:59:59.000Z

72

The effect of oxygen flow rate and radio frequency plasma power on cubic ZnMgO ultraviolet sensors grown by plasma-enhanced molecular beam epitaxy  

SciTech Connect (OSTI)

Cubic Zn{sub 1-x}Mg{sub x}O thin films were produced by Plasma-Enhanced Molecular Beam Epitaxy. Oxygen flow rate and applied Radio-Frequency (RF) plasma power were varied to investigate the impact on film growth and optoelectronic device performance. Solar-blind and visible-blind detectors were fabricated with metal-semiconductor-metal interdigitated Ni/Mg/Au contacts and responsivity is compared under different growth conditions. Increasing oxygen flow rate and RF plasma power increased Zn incorporation in the film, which leads to phase segregation at relatively high Zn/Mg ratio. Responsivity as high as 61 A/W was measured in phase-segregated ZnMgO visible-blind detectors.

Casey Boutwell, R.; Wei Ming; Schoenfeld, Winston V. [CREOL, College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816-2700 (United States)

2013-07-15T23:59:59.000Z

73

Dependence of the Mg-related acceptor ionization energy with the acceptor concentration in p-type GaN layers grown by molecular beam epitaxy  

SciTech Connect (OSTI)

Hall effect and capacitance-voltage C(V) measurements were performed on p-type GaN:Mg layers grown on GaN templates by molecular beam epitaxy with a high range of Mg-doping concentrations. The free hole density and the effective dopant concentration N{sub A}-N{sub D} as a function of magnesium incorporation measured by secondary ion mass spectroscopy clearly reveal both a magnesium doping efficiency up to 90% and a strong dependence of the acceptor ionization energy Ea with the acceptor concentration N{sub A}. These experimental observations highlight an isolated acceptor binding energy of 245{+-}25 meV compatible, at high acceptor concentration, with the achievement of p-type GaN:Mg layers with a hole concentration at room temperature close to 10{sup 19} cm{sup -3}.

Brochen, Stephane; Brault, Julien; Chenot, Sebastien; Dussaigne, Amelie; Leroux, Mathieu; Damilano, Benjamin [CNRS-CRHEA, Rue Bernard Gregory, F-06560 Valbonne (France)

2013-07-15T23:59:59.000Z

74

Observation of columnar microstructure in lattice-matched InAlN/GaN grown by plasma assisted molecular beam epitaxy  

SciTech Connect (OSTI)

Nominally lattice matched InAlN/GaN was grown by plasma-assisted molecular beam epitaxy, and the intrinsic microstructure was investigated via x-ray diffraction, transmission electron microscopy, and atom probe tomography. The InAlN showed a cellular structure, which was comprised of {approx}10 nm wide Al-rich cores and {approx}1 nm In-rich InAlN intercellular boundaries. Despite the strong laterally non-uniform In distribution, both vertical and lateral lattices are unperturbed by the cellular structure, as evidenced by strong thickness fringes in on-axis {omega}-2{theta} high resolution x-ray diffraction scans, coherence lengths derived from on-axis (0002) and off-axis (1012) {omega}-2{theta} high resolution x-ray diffraction scans, and a modified Williamson-Hall analysis for on-axis reflections.

Choi, Soojeong; Wu Feng; Shivaraman, Ravi; Young, Erin C.; Speck, James S. [Materials Department, University of California, Santa Barbara, California 93106 (United States)

2012-06-04T23:59:59.000Z

75

Structural and optical characterization of Si{sub x}Ge{sub 1-x-y}Sn{sub y} alloys grown by molecular beam epitaxy  

SciTech Connect (OSTI)

Si{sub x}Ge{sub 1-x-y}Sn{sub y} alloys were grown by molecular beam epitaxy at low temperature, followed by ex-situ annealing. The crystal quality of Si{sub x}Ge{sub 1-x-y}Sn{sub y} layers was characterized by atomic force microscopy and transmission electron microscopy. The compositions and lattice constants of the alloys were studied by x-ray photoelectron spectroscopy and x-ray diffraction. The results show that Vegard's law is a good approximation for Si{sub x}Ge{sub 1-x-y}Sn{sub y} alloys. Photoreflectance spectroscopy at room temperature was used to determine the direct bandgap energy of Si{sub x}Ge{sub 1-x-y}Sn{sub y} layers. Analyzing the relationship between composition and direct bandgap energy reveals a negative energy bowing parameter for SiSn.

Lin, Hai [Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States); Chen, Robert; Huo Yijie; Kamins, Theodore I.; Harris, James S. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Lu Weisheng [Institute of Photonics, University of Strathclyde, Glasgow G4 0NW (United Kingdom)

2012-04-02T23:59:59.000Z

76

Molecular beam epitaxial growth and characterization of mixed (Ti,Nb)O{sub 2} rutile films on TiO{sub 2}(100)  

SciTech Connect (OSTI)

Epitaxial films of mixed (Nb,Ti)O{sub 2} rutile have been grown on TiO{sub 2}(100) rutile at 600{degree}C by molecular beam epitaxy. These films grow in a laminar fashion for Nb mole fractions up to {approximately}0.10. In addition, reflection high-energy and low-energy electron diffraction, along with x-ray photoelectron diffraction and Rutherford backscattering reveal that the overlayers possess excellent long- and short-range structure order up to 10 at.{percent}. However, strain-induced disorder becomes prevalent for higher Nb mole fractions, and the surfaces roughen and become defected accordingly. X-ray photoelectron diffraction and Rutherford backscattering reveal that Nb atoms substitutionally incorporate at cation sites in the rutile lattice for all Nb mole fractions investigated, leading to a mixed rutile Nb{sub {ital x}}Ti{sub 1{minus}{ital x}}O{sub 2} phase. Analysis of Nb 3{ital d} and Ti 2{ital p} core-level binding energies reveals that the oxidation state of both Ti and Nb is +4. {copyright} {ital 1996 American Vacuum Society}

Chambers, S.A.; Gao, Y.; Thevuthasan, S.; Liang, Y. [Environmental Molecular Sciences Laboratory, Pacific Northwest Laboratory, Richland, Washington 99352 (United States)] [Environmental Molecular Sciences Laboratory, Pacific Northwest Laboratory, Richland, Washington 99352 (United States); Shivaparan, N.R.; Smith, R.J. [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States)] [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States)

1996-05-01T23:59:59.000Z

77

Structural and band alignment properties of Al{sub 2}O{sub 3} on epitaxial Ge grown on (100), (110), and (111)A GaAs substrates by molecular beam epitaxy  

SciTech Connect (OSTI)

Structural and band alignment properties of atomic layer Al{sub 2}O{sub 3} oxide film deposited on crystallographically oriented epitaxial Ge grown in-situ on (100), (110), and (111)A GaAs substrates using two separate molecular beam epitaxy chambers were investigated using cross-sectional transmission microscopy (TEM) and x-ray photoelectron spectroscopy (XPS). High-resolution triple axis x-ray measurement demonstrated pseudomorphic and high-quality Ge epitaxial layer on crystallographically oriented GaAs substrates. The cross-sectional TEM exhibited a sharp interface between the Ge epilayer and each orientation of the GaAs substrate as well as the Al{sub 2}O{sub 3} film and the Ge epilayer. The extracted valence band offset, {Delta}E{sub v}, values of Al{sub 2}O{sub 3} relative to (100), (110), and (111) Ge orientations using XPS measurement were 3.17 eV, 3.34 eV, and 3.10 eV, respectively. Using XPS data, variations in {Delta}E{sub v} related to the crystallographic orientation were {Delta}E{sub V}(110)Ge>{Delta}E{sub V}(100)Ge{>=}{Delta}E{sub V}(111)Ge and the conduction band offset, {Delta}E{sub c}, related to the crystallographic orientation was {Delta}E{sub c}(111)Ge>{Delta}E{sub c}(110)Ge>{Delta}E{sub c}(100)Ge using the measured {Delta}E{sub v}, bandgap of Al{sub 2}O{sub 3} in each orientation, and well-known Ge bandgap of 0.67 eV. These band offset parameters are important for future application of Ge-based p- and n-channel metal-oxide field-effect transistor design.

Hudait, M. K.; Zhu, Y. [Advanced Devices and Sustainable Energy Laboratory (ADSEL), Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Maurya, D.; Priya, S. [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Patra, P. K. [Department of Biomedical Engineering and Department of Mechanical Engineering, University of Bridgeport, Bridgeport, Connecticut 06604 (United States); Ma, A. W. K. [Department of Chemical and Biomolecular Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Aphale, A.; Macwan, I. [Department of Electrical and Computer Engineering, University of Bridgeport, Bridgeport, Connecticut 06604 (United States)

2013-04-07T23:59:59.000Z

78

?-function-shaped Sb-doping profiles in Si(001) obtained using a low-energy accelerated-ion source during molecular-beam epitaxy  

Science Journals Connector (OSTI)

Two-dimensional (2D) buried ?-function-shaped Sb-doping profiles have been obtained in Si using a low-energy accelerated Sb-ion source during molecular-beam epitaxy. A combination of secondary-ion mass spectrometry (SIMS), capacitance-voltage (C-V) measurements, and cross-sectional transmission electron microscopy (XTEM) was used to investigate dopant distributions and to determine profile widths. The 2D-sheet Sb-doping concentration NSb, obtained by integrating SIMS ?-doping profiles in samples grown with substrate temperature Ts=620 °C and Sb-ion acceleration potentials VSb=200 and 300 V, was found to vary linearly with the product of the Sb-ion flux and the exposure time (i.e., the ion dose) over the NSb range from 5×1012 to 2×1014 cm-2. The full width at half maximum (FWHM) concentration of ?-doping profiles in Si(001) films was less than the depth resolution of both SIMS and C-V measurements (?10 and 3 nm, respectively). High-resolution XTEM lattice images show that the FWHM was ?2 nm. This is consistent with dopant incorporation simulations, based upon a multisite transition-state dopant incorporation model, which show that accelerated-beam dopant species are trapped in near-surface substitutional sites with atomic mobilities between those of surface and bulk atoms. Dopant surface segregation during growth is strongly suppressed, and the dopant distribution is determined primarily by the straggle in ion trapping distributions. The present results are compared with profile broadening observed in ?-doped layers obtained by solid-phase epitaxy of amorphous Si containing a buried Sb layer.

W.-X. Ni; G. V. Hansson; J.-E. Sundgren; L. Hultman; L. R. Wallenberg; J.-Y. Yao; L. C. Markert; J. E. Greene

1992-09-15T23:59:59.000Z

79

Hall and electroreflectance studies of the effects of doping in mercury–cadmium telluride grown by molecular?beam epitaxy  

Science Journals Connector (OSTI)

Hall and electrolyte electroreflectance (EER) measurements have been performed on a series of mercury–cadmium telluride samples grown by molecular?beam heteroepitaxy on semi?insulating GaAs substrates and varying from p type to heavily dopedn type. Our results show for as?grown n?type samples grown under nearly ideal conditions that the mobilities are high and that the n character is not primarily associated with defects. Our Hall results show that as one departs from nearly ideal growth conditions in order to obtain higher n?type doping levels the mobility decreases precipitously. An analysis of the temperature dependence of the mobility suggests that this decrease is associated with a rapid increase in both the number of ionized impurities and the number of neutral scattering centers. Our EER results show that the initial decrease of the mobility is associated with the formation of inhomogeneous strains and to a lesser extent both point defects and two?dimensional structural faults. They also show that the final precipitous decline in the high?temperature mobility is associated with a decrease in the density of inhomogeneous strains accompanied by the formation of many more two?dimensional structural faults although they are not sensitive to the high degree of compensation which is largely responsible for the precipitous decline in the low?temperature mobility.

Paul M. Raccah; J. W. Garland; Z. Zhang; Amy H. M. Chu; J. Reno; I. K. Sou; M. Boukerche; J. P. Faurie

1986-01-01T23:59:59.000Z

80

Homogeneous AlGaN/GaN superlattices grown on free-standing (1100) GaN substrates by plasma-assisted molecular beam epitaxy  

SciTech Connect (OSTI)

Two-dimensional and homogeneous growth of m-plane AlGaN by plasma-assisted molecular beam epitaxy has been realized on free-standing (1100) GaN substrates by implementing high metal-to-nitrogen (III/N) flux ratio. AlN island nucleation, often reported for m-plane AlGaN under nitrogen-rich growth conditions, is suppressed at high III/N flux ratio, highlighting the important role of growth kinetics for adatom incorporation. The homogeneity and microstructure of m-plane AlGaN/GaN superlattices are assessed via a combination of scanning transmission electron microscopy and high resolution transmission electron microscopy (TEM). The predominant defects identified in dark field TEM characterization are short basal plane stacking faults (SFs) bounded by either Frank-Shockley or Frank partial dislocations. In particular, the linear density of SFs is approximately 5 × 10{sup ?5} cm{sup ?1}, and the length of SFs is less than 15 nm.

Shao, Jiayi; Malis, Oana [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States) [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States); Zakharov, Dmitri N. [Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973 (United States)] [Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973 (United States); Edmunds, Colin [Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States)] [Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States); Manfra, Michael J. [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States) [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States); School of Materials Engineering, Purdue University, West Lafayette, Indiana 49707 (United States); School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 49707 (United States)

2013-12-02T23:59:59.000Z

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.


81

Design of an ultrahigh vacuum transfer mechanism to interconnect an oxide molecular beam epitaxy growth chamber and an x-ray photoemission spectroscopy analysis system  

SciTech Connect (OSTI)

We designed a mechanism and the accompanying sample holders to transfer between a VEECO 930 oxide molecular beam epitaxy (MBE) and a PHI Versa Probe X-ray photoemission spectroscopy (XPS) chamber within a multiple station growth, processing, and analysis system through ultrahigh vacuum (UHV). The mechanism consists of four parts: (1) a platen compatible with the MBE growth stage, (2) a platen compatible with the XPS analysis stage, (3) a sample coupon that is transferred between the two platens, and (4) the accompanying UHV transfer line. The mechanism offers a robust design that enables transfer back and forth between the growth chamber and the analysis chamber, and yet is flexible enough to allow transfer between standard sample holders for thin film growth and masked sample holders for making electrical contacts and Schottky junctions, all without breaking vacuum. We used this mechanism to transfer a barium strontium titanate thin film into the XPS analysis chamber and performed XPS measurements before and after exposing the sample to the air. After air exposure, a thin overlayer of carbon was found to form and a significant shift ({approx}1 eV) in the core level binding energies was observed.

Rutkowski, M. M.; Zeng Zhaoquan [Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States); McNicholas, K. M. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Brillson, L. J. [Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States); Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States)

2013-06-15T23:59:59.000Z

82

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

SciTech Connect (OSTI)

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

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

2014-07-07T23:59:59.000Z

83

Electronic structure, morphology and emission polarization of enhanced symmetry InAs quantum-dot-like structures grown on InP substrates by molecular beam epitaxy  

SciTech Connect (OSTI)

The optical and structural properties of a new kind of InAs/InGaAlAs/InP quantum dot (QD)-like objects grown by molecular beam epitaxy have been investigated. These nanostructures were found to have significantly more symmetrical shapes compared to the commonly obtained dash-like geometries typical of this material system. The enhanced symmetry has been achieved due to the use of an As{sub 2} source and the consequent shorter migration length of the indium atoms. Structural studies based on a combination of scanning transmission electron microscopy (STEM) and atom probe tomography (APT) provided detailed information on both the structure and composition distribution within an individual nanostructure. However, it was not possible to determine the lateral aspect ratio from STEM or APT. To verify the in-plane geometry, electronic structure calculations, including the energy levels and transition oscillator strength for the QDs have been performed using an eight-band k·p model and realistic system parameters. The results of calculations were compared to measured polarization-resolved photoluminescence data. On the basis of measured degree of linear polarization of the surface emission, the in-plane shape of the QDs has been assessed proving a substantial increase in lateral symmetry. This results in quantum-dot rather than quantum-dash like properties, consistent with expectations based on the growth conditions and the structural data.

Mary?ski, A.; S?k, G.; Musia?, A.; Andrzejewski, J.; Misiewicz, J. [Institute of Physics, Wroc?aw University of Technology, Wybrze?e Wyspia?skiego 27, 50-370 Wroc?aw (Poland)] [Institute of Physics, Wroc?aw University of Technology, Wybrze?e Wyspia?skiego 27, 50-370 Wroc?aw (Poland); Gilfert, C.; Reithmaier, J. P. [Technische Physik, Institute of Nanostructure Technology and Analytics, CINSaT, University of Kassel, Heinrich Plett-Str. 40, D-34132 Kassel (Germany)] [Technische Physik, Institute of Nanostructure Technology and Analytics, CINSaT, University of Kassel, Heinrich Plett-Str. 40, D-34132 Kassel (Germany); Capua, A.; Karni, O.; Gready, D.; Eisenstein, G. [Department of Electrical Engineering, Technion, Haifa 32000 (Israel)] [Department of Electrical Engineering, Technion, Haifa 32000 (Israel); Atiya, G.; Kaplan, W. D. [Department of Materials Science and Engineering, Technion, Haifa 32000 (Israel)] [Department of Materials Science and Engineering, Technion, Haifa 32000 (Israel); Kölling, S. [Fraunhofer Institute for Photonic Microsystems, Center for Nanoelectronic Technologies, Königsbrücker Straße 180, D-01099 Dresden (Germany)] [Fraunhofer Institute for Photonic Microsystems, Center for Nanoelectronic Technologies, Königsbrücker Straße 180, D-01099 Dresden (Germany)

2013-09-07T23:59:59.000Z

84

Photoacoustic signals of n-type GaAs layers grown by molecular-beam epitaxy on semi-insulating substrates  

Science Journals Connector (OSTI)

Piezoelectric photoacoustic (PA) measurements of molecular-beam-epitaxial (MBE) -grown GaAs layers were carried out in the temperature range from 90 to 290 K. A broad D band with a maximum near 1.3 eV and a sharp Q peak at 1.485 eV have been observed in the 90-K spectra. They vanish in a presence of secondary light illumination. By comparing with optical-absorption spectra, it is considered that the D band is due to electron transitions involving EL2 deep defect levels in the GaAs substrate. The PA signal is considered to be enhanced by the presence of the electric field at the interface between the MBE layer and the substrate. The Q peak is attributed to electron transitions from shallow acceptors such as carbon in GaAs. Observed photoinduced changes in the spectra are explained by a reduction of the electric field in the depletion region which is induced by optical carrier generation.

T. Ikari; A. Fukuyama; K. Maeda; K. Futagami; S. Shigetomi; Y. Akashi

1992-10-15T23:59:59.000Z

85

Electronic structures and magnetic moments of Co{sub 3}FeN thin films grown by molecular beam epitaxy  

SciTech Connect (OSTI)

We evaluated electronic structures and magnetic moments in Co{sub 3}FeN epitaxial films on SrTiO{sub 3}(001). The experimentally obtained hard x-ray photoemission spectra of the Co{sub 3}FeN film have a good agreement with those calculated. Site averaged spin magnetic moments deduced by x-ray magnetic circular dichroism were 1.52 ?{sub B} per Co atom and 2.08 ?{sub B} per Fe atom at 100 K. They are close to those of Co{sub 4}N and Fe{sub 4}N, respectively, implying that the Co and Fe atoms randomly occupy the corner and face-centered sites in the Co{sub 3}FeN unit cell.

Ito, Keita; Sanai, Tatsunori; Yasutomi, Yoko; Toko, Kaoru; Honda, Syuta; Suemasu, Takashi [Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)] [Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Zhu, Siyuan; Kimura, Akio [Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)] [Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Ueda, Shigenori [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148 (Japan)] [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148 (Japan); Takeda, Yukiharu; Saitoh, Yuji [Condensed Matter Science Division, Japan Atomic Energy Agency (JAEA), 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148 (Japan)] [Condensed Matter Science Division, Japan Atomic Energy Agency (JAEA), 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148 (Japan); Imai, Yoji [Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan) [Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan)

2013-12-02T23:59:59.000Z

86

Structure and magnetism in strained Ge{sub 1-x-y}Sn{sub x}Mn{sub y} films grown on Ge(001) by low temperature molecular beam epitaxy  

SciTech Connect (OSTI)

In this letter, we study the structural and magnetic properties of Ge{sub 1-x-y}Sn{sub x}Mn{sub y} films grown on Ge(001) by low temperature molecular beam epitaxy using X-ray diffraction, high resolution transmission electron microscopy, and superconducting quantum interference device. Like in Mn doped Ge films, Mn atoms diffuse during the growth and aggregate into vertically aligned Mn-rich nanocolumns of a few nanometers in diameter. Transmission electron microscopy observations in plane view clearly indicate that the Sn incorporation is not uniform with concentration in Mn rich vertical nanocolumns lower than the detection limit of electron energy loss spectroscopy. The matrix exhibits a GeSn solid solution while there is a Sn-rich GeSn shell around GeMn nanocolumns. The magnetization in Ge{sub 1-x-y}Sn{sub x}Mn{sub y} layers is higher than in Ge{sub 1-x}Mn{sub x} films. This magnetic moment enhancement in Ge{sub 1-x-y}Sn{sub x}Mn{sub y} is probably related to the modification of the electronic structure of Mn atoms in the nanocolumns by the Sn-rich shell, which is formed around the nanocolumns.

Prestat, E. [INAC, SP2M, CEA and Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France); Karlsruher Institut fuer Technologie (KIT), Laboratorium fuer Elektronenmikroskopie, D-76128 Karlsruhe (Germany); Barski, A.; Bellet-Amalric, E.; Morel, R.; Tainoff, D.; Jain, A.; Porret, C.; Bayle-Guillemaud, P.; Jamet, M. [INAC, SP2M, CEA and Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France); Jacquot, J.-F. [INAC, SCIB, CEA and Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France)

2013-07-01T23:59:59.000Z

87

REVIEW ARTICLE Taming molecular beams  

E-Print Network [OSTI]

REVIEW ARTICLE Taming molecular beams The motion of neutral molecules in a beam can be manipulated time-varying fields can be used to decelerate or accelerate beams of molecules to any desired velocity. We review the possibilities that this molecular-beam technology offers, ranging from ultrahigh

Loss, Daniel

88

A compact molecular beam machine  

SciTech Connect (OSTI)

We have developed a compact, low cost, modular, crossed molecular beam machine. The new apparatus utilizes several technological advancements in molecular beams valves, ion detection, and vacuum pumping to reduce the size, cost, and complexity of a molecular beam apparatus. We apply these simplifications to construct a linear molecular beam machine as well as a crossed-atomic and molecular beam machine. The new apparatus measures almost 50 cm in length, with a total laboratory footprint less than 0.25 m{sup 2} for the crossed-atomic and molecular beam machine. We demonstrate the performance of the apparatus by measuring the rotational temperature of nitric oxide from three common molecular beam valves and by observing collisional energy transfer in nitric oxide from a collision with argon.

Jansen, Paul [Vrije Universiteit, 1081 HV Amsterdam (Netherlands); Chandler, David W.; Strecker, Kevin E. [Sandia National Laboratories, Livermore, California 94551 (United States)

2009-08-15T23:59:59.000Z

89

Molecular-beam scattering  

SciTech Connect (OSTI)

The molecular-beam technique has been used in three different experimental arrangements to study a wide range of inter-atomic and molecular forces. Chapter 1 reports results of a low-energy (0.2 kcal/mole) elastic-scattering study of the He-Ar pair potential. The purpose of the study was to accurately characterize the shape of the potential in the well region, by scattering slow He atoms produced by expanding a mixture of He in N/sub 2/ from a cooled nozzle. Chapter 2 contains measurements of the vibrational predissociation spectra and product translational energy for clusters of water, benzene, and ammonia. The experiments show that most of the product energy remains in the internal molecular motions. Chapter 3 presents measurements of the reaction Na + HCl ..-->.. NaCl + H at collision energies of 5.38 and 19.4 kcal/mole. This is the first study to resolve both scattering angle and velocity for the reaction of a short lived (16 nsec) electronic excited state. Descriptions are given of computer programs written to analyze molecular-beam expansions to extract information characterizing their velocity distributions, and to calculate accurate laboratory elastic-scattering differential cross sections accounting for the finite apparatus resolution. Experimental results which attempted to determine the efficiency of optically pumping the Li(2/sup 2/P/sub 3/2/) and Na(3/sup 2/P/sub 3/2/) excited states are given. A simple three-level model for predicting the steady-state fraction of atoms in the excited state is included.

Vernon, M.F.

1983-07-01T23:59:59.000Z

90

High-efficiency GaAs and GaInP solar cells grown by all solid-state molecular-beam-epitaxy  

Science Journals Connector (OSTI)

We report the initial results of GaAs and GaInP solar cells grown by all solid-state molecular- ... (MBE) technique. For GaAs single-junction solar cell, with the application of AlInP as ... back surface field la...

Shulong Lu; Lian Ji; Wei He; Pan Dai; Hui Yang…

2011-10-01T23:59:59.000Z

91

Chemical beam epitaxy for high efficiency photovoltaic devices  

SciTech Connect (OSTI)

InP-based multijunction tandem solar cells show great promise for the conversion efficiency (eta) and high radiation resistance. InP and its related ternary and quanternary compound semiconductors such as InGaAs and InGaAsP offer desirable combinations for energy bandgap values which are very suitable for multijunction tandem solar cell applications. The monolithically integrated InP/In(0.53)Ga(0.47)As tandem solar cells are expected to reach efficiencies above 30 percent. Wanlass, et.al., have reported AMO efficiencies as high as 20.1% for two terminal cells fabricated using atmospheric-pressure metalorganic vapor phase epitaxy (APMOVPE). The main limitations in their technique are first related to the degradation of the intercell ohmic contact (IOC), in this case the In(0.53)Ga(0.47)As tunnel junction during the growth of the top InP subcell structure, and second to the current matching, often limited by the In(0.53)Ga(0.47)As bottom subcell. Chemical beam epitaxy (CBE) has been shown to allow the growth of high quality materials with reproducible complex compositional and doping profiles. The main advantage of CBE compared to metalorganic chemical vapor deposition (MOCVD), the most popular technique for InP-based photovoltaic device fabrication, is the ability to grow high purity epilayers at much lower temperatures (450 C - 530 C). In a recent report it was shown that cost-wise CBE is a breakthrough technology for photovoltaic (PV) solar energy progress in the energy conversion efficiency of InP-based solar cells fabricated using chemical beam epitaxy. This communication summarizes recent results on PV devices and demonstrates the strength of this new technology.

Bensaoula, A.; Freundlich, A.; Vilela, M. F.; Medelci, N.; Renaud, P.

1994-09-01T23:59:59.000Z

92

Chemical beam epitaxy growth of III–V semiconductor nanowires  

SciTech Connect (OSTI)

Indium- Arsenide (InAs) nanowires were grown in a high vacuum chemical beam epitaxy (CBE) unit on InAs(111) wafers substrates at 425–454°C. Two types of nanogold were used as orientation catalyst, 40nm and 80nm. The measurements were performed using scanning electron microscopy showed that uniform nanowires. The nanowires orient vertically in the InAs nanowire scanning electron microscopy of an array 80nm diameter InAs nanowire with length is in the range 0.5–1 ?m and of an array 40nm diameter with length is in the range 0.3–0.7?m. The nanowire length with growth time shows that the linear increase of nanowires start to grow as soon as TMIn is available. The growth rate with temperature was studied.

Mohummed Noori, Farah T. [University of Baghdad , College of science, Physics department , Jadiriya ,Baghdad (Iraq)

2013-12-16T23:59:59.000Z

93

Hydrogen-mediated quenching of strain-induced surface roughening during gas-source molecular beam epitaxy of fully-coherent Si0.7Ge0.3  

E-Print Network [OSTI]

Hydrogen-mediated quenching of strain-induced surface roughening during gas-source molecular beam of thickness t at temperatures, Ts 450­550 °C, for which strain-induced roughening is observed during solid scientific and technological reasons. Predicting and minimizing sur- face roughening is required

Spila, Timothy P.

94

Structural and Magnetic Properties of Epitaxial MnSi(111) Thin Films.  

E-Print Network [OSTI]

??MnSi(111) films were grown on Si(111) substrates by solid phase epitaxy (SPE) and molecular beam epitaxy (MBE) to determine their magnetic structures. A lattice mismatch… (more)

Karhu, Eric

2012-01-01T23:59:59.000Z

95

Yuan T. Lee and Molecular Beam Studies  

Office of Scientific and Technical Information (OSTI)

rapidly became a mecca for studies of collision processes. Later, lasers and molecular beams were combined to understand various primary photochemical processes and the...

96

14th international symposium on molecular beams  

SciTech Connect (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

97

14th international symposium on molecular beams  

SciTech Connect (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

1992-09-01T23:59:59.000Z

98

Yuan T. Lee's Crossed Molecular Beam Experiment  

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

99

Band Offsets at the Epitaxial Anatase TiO2/n-SrTiO3(001) Interface...  

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

to measure valence band offsets at the epitaxial anatase TiO2(002)n-SrTiO3(001) heterojunction prepared by molecular beam epitaxy, Within experimental error, the valance band...

100

Defect ordering in epitaxial a-GaN(QQ01) H. Z. Xiao, N.-E. Lee, R. C. Powell,") Z. Ma, L. J. Chou,b) L. H. Allen, J. E. Greene,  

E-Print Network [OSTI]

epitaxial wurtzite-structure o-GaN films, grown by gas-source molecular-beam epitaxy, plasma-assisted, including gas-source molecular-beam epitaxy (GSMBE),' reactive-ion MBE (RIMBE), plasma- assisted MBE (PAMBE- purity (99.9995%) NH3 flux, regulated with a mass-flow con- `kurrent address: Solar Cells Inc., 1702 N

Allen, Leslie H.

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While these samples are representative of the content of NLEBeta,
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We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Dudley Herschbach: Chemical Reactions and Molecular Beams  

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

102

Publications, Oxide Molecular Beam Epitaxy Group, Condensed Matter Physics  

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

103

Laboratories, Oxide Molecular Beam Epitaxy Group, Condensed Matter Physics  

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

104

Applied Super Conductor Group, Oxide Molecular Beam Epitaxy Group,  

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

105

Collaborations, Oxide Molecular Beam Epitaxy Group, Condensed Matter  

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

106

Counting molecular-beam grown graphene layers  

SciTech Connect (OSTI)

We have used the ratio of the integrated intensity of graphene's Raman G peak to that of the silicon substrate's first-order optical phonon peak, accurately to determine the number of graphene layers across our molecular-beam (MB) grown graphene films. We find that these results agree well both, with those from our own exfoliated single and few-layer graphene flakes, and with the results of Koh et al.[ACS Nano 5, 269 (2011)]. We hence distinguish regions of single-, bi-, tri-, four-layer, etc., graphene, consecutively, as we scan coarsely across our MB-grown graphene. This is the first, but crucial, step to being able to grow, by such molecular-beam-techniques, a specified number of large-area graphene layers, to order.

Plaut, Annette S. [School of Physics, University of Exeter, Exeter EX4 4QL (United Kingdom)] [School of Physics, University of Exeter, Exeter EX4 4QL (United Kingdom); Wurstbauer, Ulrich [Department of Physics, Columbia University, New York, New York 10027 (United States)] [Department of Physics, Columbia University, New York, New York 10027 (United States); Pinczuk, Aron [Department of Physics, Columbia University, New York, New York 10027 (United States) [Department of Physics, Columbia University, New York, New York 10027 (United States); Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States); Garcia, Jorge M. [MBE Lab, IMM-Instituto de Microelectronica de Madrid (CNM-CSIC), Madrid, E-28760 (Spain)] [MBE Lab, IMM-Instituto de Microelectronica de Madrid (CNM-CSIC), Madrid, E-28760 (Spain); Pfeiffer, Loren N. [Electrical Engineering Department, Princeton University, New Jersey 08544 (United States)] [Electrical Engineering Department, Princeton University, New Jersey 08544 (United States)

2013-06-17T23:59:59.000Z

107

Molecular beam studies of reaction dynamics  

SciTech Connect (OSTI)

Purpose of this research project is two-fold: (1) to elucidate detailed dynamics of simple elementary reactions which are theoretically important and to unravel the mechanism of complex chemical reactions or photo chemical processes which play an important role in many macroscopic processes and (2) to determine the energetics of polyatomic free radicals using microscopic experimental methods. Most of the information is derived from measurement of the product fragment translational energy and angular distributions using unique molecular beam apparati designed for these purposes.

Lee, Y.T.

1987-03-01T23:59:59.000Z

108

Epitaxial growth of europium monoxide on diamond  

SciTech Connect (OSTI)

We report the epitaxial integration of phase-pure EuO on both single-crystal diamond and on epitaxial diamond films grown on silicon utilizing reactive molecular-beam epitaxy. The epitaxial orientation relationship is (001) EuO ? (001) diamond and [110] EuO ?[100] diamond. The EuO layer is nominally unstrained and ferromagnetic with a transition temperature of 68 ± 2 K and a saturation magnetization of 5.5 ± 0.1 Bohr magnetons per europium ion on the single-crystal diamond, and a transition temperature of 67 ± 2 K and a saturation magnetization of 2.1 ± 0.1 Bohr magnetons per europium ion on the epitaxial diamond film.

Melville, A.; Heeg, T. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States)] [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Mairoser, T.; Schmehl, A. [Zentrum für elektronische Korrelationen und Magnetismus, Universität Augsburg, Universitätsstraße 1, 86159 Augsburg (Germany)] [Zentrum für elektronische Korrelationen und Magnetismus, Universität Augsburg, Universitätsstraße 1, 86159 Augsburg (Germany); Fischer, M.; Gsell, S.; Schreck, M. [Institut für Physik, Universität Augsburg, D-86135 Augsburg (Germany)] [Institut für Physik, Universität Augsburg, D-86135 Augsburg (Germany); Awschalom, D. D. [Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637 (United States)] [Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637 (United States); Holländer, B.; Schubert, J. [Peter Grünberg Institute, PGI9-IT, JARA-FIT, Research Centre Jülich, D-52425 Jülich (Germany)] [Peter Grünberg Institute, PGI9-IT, JARA-FIT, Research Centre Jülich, D-52425 Jülich (Germany); Schlom, D. G. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States) [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

2013-11-25T23:59:59.000Z

109

Chemical beam epitaxy growth of AlGaAs/GaAs tunnel junctions using trimethyl aluminium for multijunction solar cells  

SciTech Connect (OSTI)

AlGaAs/GaAs tunnel junctions for use in high concentration multijunction solar cells were designed and grown by chemical beam epitaxy (CBE) using trimethyl aluminium (TMA) as the p-dopant source for the AlGaAs active layer. Controlled hole concentration up to 4?10{sup 20} cm{sup ?3} was achieved through variation in growth parameters. Fabricated tunnel junctions have a peak tunneling current up to 6140 A/cm{sup 2}. These are suitable for high concentration use and outperform GaAs/GaAs tunnel junctions.

Paquette, B.; DeVita, M.; Turala, A.; Kolhatkar, G.; Boucherif, A.; Jaouad, A.; Aimez, V.; Arès, R. [Institut Interdisciplinaire d'Innovation Technologique (3IT), Université de Sherbrooke, Sherbrooke, Québec (Canada)] [Institut Interdisciplinaire d'Innovation Technologique (3IT), Université de Sherbrooke, Sherbrooke, Québec (Canada); Wilkins, M.; Wheeldon, J. F.; Walker, A. W.; Hinzer, K. [Centre for Research in Photonics, University of Ottawa, Ottawa, ON (Canada)] [Centre for Research in Photonics, University of Ottawa, Ottawa, ON (Canada); Fafard, S. [Cyrium Technologies Inc., Ottawa, ON (Canada)] [Cyrium Technologies Inc., Ottawa, ON (Canada)

2013-09-27T23:59:59.000Z

110

Molecular beam studies of reaction dynamics  

SciTech Connect (OSTI)

The major thrust of this research project is to elucidate detailed dynamics of simple elementary reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation.

Lee, Y.T. [Lawrence Berkeley Laboratory, CA (United States)

1993-12-01T23:59:59.000Z

111

Molecular beam studies of reaction dynamics  

SciTech Connect (OSTI)

The major thrust of this research project is to elucidate detailed dynamics of simple elementary reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation.

Lee, Yuan T.

1991-03-01T23:59:59.000Z

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

Multiperiod quantum-cascade nanoheterostructures: Epitaxy and diagnostics  

SciTech Connect (OSTI)

Advances in the production technology of multiperiod nanoheterostructures of quantum-cascade lasers with 60 cascades by molecular-beam epitaxy (MBE) on an industrial multiple-substrate MBE machine are discussed. The results obtained in studying the nanoheterostructures of quantum-cascade lasers by transmission electron microscopy, high-resolution X-ray diffraction analysis, and photoluminescence mapping are presented.

Egorov, A. Yu., E-mail: Anton@beam.ioffe.ru; Brunkov, P. N.; Nikitina, E. V.; Pirogov, E. V.; Sobolev, M. S.; Lazarenko, A. A. [Russian Academy of Sciences, St. Petersburg Academic University, Nanotechnology Research and Education Center (Russian Federation); Baidakova, M. V.; Kirilenko, D. A.; Konnikov, S. G. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

2014-12-15T23:59:59.000Z

114

The effect of cluster formation on mass separation in binary molecular beams  

E-Print Network [OSTI]

The effect of cluster formation on mass separation in binary molecular beams Wei Li,a) M. J composition of a skimmed supersonic binary molecular beam originally consisting of a 20% neon/80% xenon. © 2000 American Institute of Physics. S0021-9606 00 01806-7 I. INTRODUCTION Supersonic molecular beam

Sibener, Steven

115

Epitaxial integration of ferromagnetic correlated oxide LaCoO{sub 3} with Si (100)  

SciTech Connect (OSTI)

We have grown epitaxial strained LaCoO{sub 3} on (100)-oriented silicon by molecular beam epitaxy using a relaxed epitaxial SrTiO{sub 3} buffer layer. Superconducting quantum interference device magnetization measurements show that, unlike the bulk material, the ground state of the strained LaCoO{sub 3} on silicon is ferromagnetic with a T{sub C} of 85 K. First principles calculations suggest that a ferromagnetic ground state can be stabilized in LaCoO{sub 3} by a sufficiently large biaxial tensile strain with the transition accompanied by a partial untilting of the CoO{sub 6} octahedra.

Posadas, A.; Berg, M.; Seo, H.; Lozanne, A. de; Demkov, A. A. [Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States); Smith, D. J. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Kirk, A. P.; Zhernokletov, D.; Wallace, R. M. [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080 (United States)

2011-01-31T23:59:59.000Z

116

Epitaxial growth of perfluoropentacene films with predefined molecular orientation: A route for single-crystal optical studies  

Science Journals Connector (OSTI)

Using atomic-force microscopy and x-ray diffraction we show that perfluoropentacene (C22F14, PFP) forms long-range ordered, epitaxial films on KCl(100) and NaF(100) cleavage planes. On both substrates the films adopt the same crystalline bulk phase, but surprisingly exhibit quite different molecular orientations, being upright oriented on NaF and recumbent oriented on KCl. Accompanied thermal desorption spectroscopy measurements indicate the absence of a stabilized seed layer, like on metals, hence suggesting that in both cases the PFP films are stabilized by an electrostatic point-in-line relationship between the outermost fluorine atoms and the alkali cations of the alkali halide surfaces. Furthermore, the transparency of both substrates was utilized to perform detailed transmission UV/Vis spectroscopy and polarized optical microscopy measurements along well-defined crystallographic directions. From these data the orientation of transition dipole moments of the various optical excitations were experimentally determined and a directional anisotropic exciton coupling was observed, which is attributed to the asymmetric molecular packing motif within the (100) plane of the PFP crystal lattice.

Tobias Breuer and Gregor Witte

2011-04-18T23:59:59.000Z

117

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

118

Optimization towards high density quantum dots for intermediate band solar cells grown by molecular beam epitaxy  

SciTech Connect (OSTI)

We report high density quantum dots (QDs) formation with optimized growth temperature and V/III ratio. At lower growth temperature, QD density is increased, due to smaller surface migration length of In adatoms. With higher V/III, the QD density is higher but it results in large clusters formation and decreases the QD uniformity. The QD solar cell was fabricated and examined. An extended spectral response in contrast to the GaAs reference cell was presented but the external quantum efficiency at energies higher than GaAs band gap is reduced, resulting from the degradation for the emitter above the strained QD layers.

Zhou, D.; Sharma, G.; Fimland, B. O. [Department of Electronics and Telecommunications, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway); Thomassen, S. F.; Reenaas, T. W. [Department of Physics, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway)

2010-02-08T23:59:59.000Z

119

Positioning effects on quantum dot solar cells grown by molecular beam epitaxy  

SciTech Connect (OSTI)

We report current-voltage and spectral response characteristics of high density InAs/GaAs quantum dot (QD) solar cells with different positions where dots are located. The short circuit current density (J{sub sc}), open circuit voltage (V{sub oc}), and external quantum efficiency of these cells under air mass 1.5 are presented and compared with a GaAs reference cell. An extended photoresponse in contrast to the GaAs reference cell was confirmed for all these cells. The effect of inserting QD layers into emitter and base region on device performance is shown. The J{sub sc} is reduced, while the V{sub oc} is maintained. The cell with QDs located toward the base side shows better performance, confirmed by both current-voltage and spectral response measurements.

Zhou, D.; Sharma, G.; Fimland, B. O. [Department of Electronics and Telecommunications, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway); Vullum, P. E.; Thomassen, S. F.; Holmestad, R.; Reenaas, T. W. [Department of Physics, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway)

2010-02-22T23:59:59.000Z

120

Growth Kinetics and Doping of Gallium Nitride Grown by rf-Plasma Assisted Molecular Beam Epitaxy  

E-Print Network [OSTI]

Thomas H. Myers, Ph.D., Chair Larry E. Halliburton, Ph.D. Nancy C. Giles, Ph.D. Charter D. Stinespring Giles, Dr. Charter Stinespring, Dr. Larry Halliburton, and Dr. Mohindar Seehra. In addition, I would

Myers, Tom

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

Investigation of HgTe-CdTe superlattices grown by molecular beam epitaxy.  

E-Print Network [OSTI]

??[Truncated abstract] Infrared detection finds application in a wide range of fields, including remote sensing, astronomy, medicine and defence. Many of these applications, which require… (more)

Hatch, Stuart D.

2010-01-01T23:59:59.000Z

122

GaN quantum dot superlattices grown by molecular beam epitaxy at high temperature  

E-Print Network [OSTI]

P-based optoelectronic devices with Si microelectronic devices. This method uses a Au-Ge eutectic alloy as the bonding. The realization of integrafion of GaAs- and InP-based optoelectronic devices with Si microelectronic components

123

Molecular beam epitaxy of InN dots on nitrided sapphire  

E-Print Network [OSTI]

potential in the optoelectronics industry. A well-knownsubstrate material in optoelectronics. In this work, we test

Romanyuk, Yaroslav E.; Dengel, Radu-Gabriel; Stebounova, Larissa V.; Leone, Stephen R.

2007-01-01T23:59:59.000Z

124

Molecular beam epitaxy of InP-based alloys for long-wavelength vertical cavity lasers  

E-Print Network [OSTI]

InGaAs and InGaAsP, are well devel- oped, having been deployed in commercial long-wavelength edge- ventional lattice-matched alloys to InP, AlInGaAs, and In- GaAsP do not have sufficient index contrast of absorption and dis- persion minima in conventional silica fiber; their circular output mode shape, low

Coldren, Larry A.

125

Synthesis of Metal Oxide Nanomaterials for Chemical Sensors by Molecular Beam Epitaxy  

SciTech Connect (OSTI)

Since the industrial revolution, detection and monitoring of toxic matter, chemical wastes, and air pollutants has become an important environmental issue. Thus, it leads to the development of chemical sensors for various environmental applications. The recent disastrous oil spills over the near-surface of ocean due to the offshore drilling emphasize the use of chemical sensors for prevention and monitoring of the processes that might lead to these mishaps.1, 2 Chemical sensors operated on a simple principle that the sensing platform undergoes a detectable change when exposed to the target substance to be sensed. Among all the types of chemical sensors, solid state gas sensors have attracted a great deal of attention due to their advantages such as high sensitivity, greater selectivity, portability, high stability and low cost.3, 4 Especially, semiconducting metal oxides such as SnO2, TiO2, and WO3 have been widely used as the active sensing platforms in solid state gas sensors.5 For the enhanced properties of solid state gas sensors, finding new sensing materials or development of existing materials will be needed. Thus, nanostructured materials such as nanotubes,6-8 nanowires,9-11 nanorods,12-15 nanobelts,16, 17 and nano-scale thin films18-23 have been synthesized and studied for chemical sensing applications.

Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Thevuthasan, Suntharampillai

2013-12-01T23:59:59.000Z

126

Wide-dynamic-range, fast-response CBr4 doping system for molecular beam epitaxy  

E-Print Network [OSTI]

to each orifice can be switched on and off independently using a pneumatic valve. The fast response time of these pneumatic valves enables us to change the doping abruptly. This system is suitable for growing sophisticated, such as beryllium and zinc, carbon has a very low diffusion coefficient1 and is less dependent on the composition,2

Coldren, Larry A.

127

Cerenkov emission induced by external beam radiation stimulates molecular fluorescence  

SciTech Connect (OSTI)

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

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 (OSTI)

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

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

SciTech Connect (OSTI)

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

131

Crossed molecular beam studies of atmospheric chemical reaction dynamics  

SciTech Connect (OSTI)

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

132

Epitaxial growth of VO{sub 2} by periodic annealing  

SciTech Connect (OSTI)

We report the growth of ultrathin VO{sub 2} films on rutile TiO{sub 2} (001) substrates via reactive molecular-beam epitaxy. The films were formed by the cyclical deposition of amorphous vanadium and its subsequent oxidation and transformation to VO{sub 2} via solid-phase epitaxy. Significant metal-insulator transitions were observed in films as thin as 2.3?nm, where a resistance change ?R/R of 25 was measured. Low angle annular dark field scanning transmission electron microscopy was used in conjunction with electron energy loss spectroscopy to study the film/substrate interface and revealed the vanadium to be tetravalent and the titanium interdiffusion to be limited to 1.6?nm.

Tashman, J. W.; Paik, H.; Merz, T. A. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Lee, J. H. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Moyer, J. A.; Schiffer, P. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Misra, R. [Department of Physics and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Mundy, J. A. [School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States); Spila, T. [Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Schubert, J. [Peter Grünberg Institute, PGI 9-IT, JARA-FIT, Research Centre Jülich, D-52425 Jülich (Germany); Muller, D. 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, D. G., E-mail: schlom@cornell.edu [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)

2014-02-10T23:59:59.000Z

133

Quantum state specific reactant preparation in a molecular beam by rapid adiabatic passage  

SciTech Connect (OSTI)

Highly efficient preparation of molecules in a specific rovibrationally excited state for gas/surface reactivity measurements is achieved in a molecular beam using tunable infrared (IR) radiation from a single mode continuous wave optical parametric oscillator (cw-OPO). We demonstrate that with appropriate focusing of the IR radiation, molecules in the molecular beam crossing the fixed frequency IR field experience a Doppler tuning that can be adjusted to achieve complete population inversion of a two-level system by rapid adiabatic passage (RAP). A room temperature pyroelectric detector is used to monitor the excited fraction in the molecular beam and the population inversion is detected and quantified using IR bleaching by a second IR-OPO. The second OPO is also used for complete population transfer to an overtone or combination vibration via double resonance excitation using two spatially separated RAP processes.

Chadwick, Helen, E-mail: helen.chadwick@epfl.ch; Hundt, P. Morten; Reijzen, Maarten E. van; Yoder, Bruce L.; Beck, Rainer D. [Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne, Lausanne (Switzerland)] [Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne, Lausanne (Switzerland)

2014-01-21T23:59:59.000Z

134

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

SciTech Connect (OSTI)

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

135

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

136

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

SciTech Connect (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

137

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

138

Influence of molecular arrangement and morphology on optical spectra of oligothiophene heterostructures grown by organic molecular-beam deposition  

Science Journals Connector (OSTI)

Heterostructures of quaterthiophene and sexithiophene were grown by organic molecular beam deposition both on fused silica and on potassium acid phthalate (001) single crystals. The influence of both the substrate and the order of deposition on the sample morphology and, in turn, on their optical properties has been investigated. In particular, by changing the deposition conditions, the heterostructures have been found to grow either in an island or in a layer by layer mode. The emission spectra of the latter show the individual quaterthiophene and sexithiophene bands, while the spectra of the island samples are related to effects of the boundary between quaterthiophene and sexithiophene.

S. Tavazzi; D. Besana; A. Borghesi; F. Meinardi; A. Sassella; R. Tubino

2002-04-26T23:59:59.000Z

139

AN INVESTIGATION OF HYDROGEN-RELATED PHENOMENON AND COMPENSATION IN ZnSe GROWN BY MOLECULAR BEAM EPITAXY  

E-Print Network [OSTI]

to thank Dr. B. R. Cooper and Dr. C. D. Stinespring for serving on my committee. I want to extend my

Myers, Tom

140

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

E-Print Network [OSTI]

??Because of its unique properties, such as extremely high mobility, high mechanical strength, good optical transparency and high chemical stability, graphene has attracted vast interests… (more)

Zhan, Ning

2011-01-01T23:59:59.000Z

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.


141

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

E-Print Network [OSTI]

windows at the source/drain areas, where the insulator filmof as-grown films. A narrow growth time window was found forthe HfO 2 thin film. However the small memory window of the

Zhan, Ning

2011-01-01T23:59:59.000Z

142

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

143

LaCrO3 heteroepitaxy on SrTiO3(001) by molecular beam epitaxy...  

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

Instruments: Ultra-high Vacuum, Low-temperature Scanning Probe Microscope Instrument, or UHV LT SPM Tags: Nanoscope IIIa topographical nanostructures nanodevices oxides catalysis...

144

High-quality InAsyP1-y step-graded buffer by molecular-beam epitaxy  

E-Print Network [OSTI]

20, 1117 ?1991?. M. W. Wanlass, J. J. Carapella, A. Duda, K.Rev. 3, 77 ?1999?. M. W. Wanlass, J. S. Ward, K. A. Emery,

2003-01-01T23:59:59.000Z

145

Molecular Beam Epitaxy of InP-Based Alloys for Long-Wavelength Vertical-Cavity Lasers  

E-Print Network [OSTI]

P-based approaches take the opposite tack: the active region materials, AlInGaAs and InGaAsP, are well developedInGaAs and InGaAsP, do not have sufficient index contrast to be effective options for DBRs with high for existing fiber-optic networks, since they take advantage of absorption and dispersion minima

Coldren, Larry A.

146

GaAs Clusters in the Quantum Size Regime: Growth on High Surface Area Silica by Molecular Beam Epitaxy  

Science Journals Connector (OSTI)

...cathodoluminescence ex-periments. Many useful comments on our manu-script were made by K. Kash, J. M. Worlock, and M. Saifi. We are especially gratefill to D. E. Aspnes for making concrete suggestions for the improvement ofour report. 8 May 1989...

C. J. SANDROFF; J. P. HARBISON; R. RAMESH; M. J. ANDREJCO; M. S. HEGDE; C. C. CHANG; E. M. VOGEL; D. M. HWANG

1989-07-28T23:59:59.000Z

147

A laser and molecular beam mass spectrometer study of low-pressure dimethyl ether flames  

SciTech Connect (OSTI)

The oxidation of dimethyl ether (DME) is studied in low-pressure flames using new molecular beam mass spectrometer and laser diagnostics. Two 30.0-Torr, premixed DME/oxygen/argon flames are investigated with stoichiometries of 0.98 and 1.20. The height above burner profiles of nine stable species and two radicals are measured. These results are compared to the detailed chemical reaction mechanism of Curran and coworkers. Generally good agreement is found between the model and data. The largest discrepancies are found for the methyl radical profiles where the model predicts qualitatively different trends in the methyl concentration with stoichiometry than observed in the experiment.

Andrew McIlroy; Toby D. Hain; Hope A. Michelsen; Terrill A. Cool

2000-12-15T23:59:59.000Z

148

Epitaxial growth and ferrimagnetic properties of Mn film on GaSb(100)  

SciTech Connect (OSTI)

We report on the epitaxial stabilization and magnetic properties of Mn films on GaSb(100) using molecular beam epitaxy, a follow-up to our previous work on the growth of Mn films on GaAs(100) [Phys. Rev. B 79, 045309 (2009)]. A strong ferrimagnetic ordering was observed which was attributed to the largely expanded lattice parameter resulting from the lattice mismatch with substrate and the enhanced thermal energy with increasing growth temperature. The observed magnetic moment of 1.16{mu}{sub B}/Mn atom was several times larger than that observed in the Mn/GaAs(100) films due to the lattice constant difference of substrates. The in-plane magnetoresistance behavior demonstrated the magnetic anisotropy that might result from the slightly distorted cubic structure of {alpha}-Mn phase under low-dimensional growth.

Feng Wuwei; Dung, Dang Duc; Shin, Yooleemi; Cho, Sunglae [Department of Physics, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Choi, Jeongyong [IT Convergence Technology Research Laboratory, Electronics and Telecommunications Research Institute, Daejeon 305-700 (Korea, Republic of)

2010-05-15T23:59:59.000Z

149

Lattice-matched epitaxial GaInAsSb/GaSb thermophotovoltaic devices  

SciTech Connect (OSTI)

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

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

1997-05-01T23:59:59.000Z

150

Monolithic integration of GaAs and h~~~~Ga~.~Aslasers by molecular epitaxy on GaAs  

E-Print Network [OSTI]

where the thick cladding layer below the active laser region acts as a buffer layer to-yield comparable epitaxial regrowth of Ino.aGaesAs lasers through dielectric masks between GaAs laser stripes on a GaAs substrate has been used for the -first time- to monolithically integrate these two lasers emitting near 1

151

Molecular Beam and Surface Science Studies of Heterogeneous Reaction Kinetics Including Combustion Dynamics. Final Technical Report.  

SciTech Connect (OSTI)

This research program examined the heterogeneous reaction kinetics and reaction dynamics of surface chemical processes which are of direct relevance to efficient energy production, condensed phase reactions, and mateials growth including nanoscience objectives. We have had several notable scientific and technical successes. Illustrative highlights include: (1) a thorough study of how one can efficiently produce synthesis gas (SynGas) at relatively low Rh(111) catalyst temperatures via the reaction CH{sub4}+1/2 O{sub2} {r_arrow} CO+2H{sub2}. In these studies methane activation is accomplished utilizing high-kinetic energy reagents generated via supersonic molecular beams, (2) experiments which have incisively probed the partial oxidation chemistry of adsorbed 1- and 2- butene on Rh and ice, as well as partial oxidation of propene on Au; (3) investigation of structural changes which occur to the reconstructed (23x{radical}3)-Au(111) surface upon exposure to atomic oxygen, (4) a combined experimental and theoretical examination of the fundamental atomic-level rules which govern defect minimization during the formation of self-organizing stepped nanostructures, (5) the use of these relatively defect-free nanotemplates for growing silicon nanowires having atomically-dimensioned widths, (6) a combined scanning probe and atomic beam scattering study of how the presence of self-assembling organic overlayers interact with metallic supports substrates - this work hs led to revision of the currently held view of how such adsorbates reconfigure surface structure at the atomic level, (7) an inelastic He atom scattering study in which we examined the effect of chain length on the low-energy vibrations of alkanethiol striped phase self-assembled monolayers on Au(111), yielding information on the forces that govern interfacial self-assembly, (8) a study of the vibrational properties of disordered films of SF{sub6} adsorbed on Au(111), and (9) a study of the activated chemistry and photochemistry of NO on NiO/Ni. Innovative STM and molecular beam instrumentation has been fabricated to enable this program.

Sibener, S. J.

2006-06-23T23:59:59.000Z

152

Epitaxial Graphene - Energy Innovation Portal  

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

Epitaxial Graphene Brookhaven National Laboratory Contact BNL About This Technology

Scanning electron micrographs of epitaxial graphene grown on ruthenium films atop patterned...

153

Interface structure and thermal stability of epitaxial SrTiO{sub 3} thin films on Si (001)  

SciTech Connect (OSTI)

We have used medium energy ion scattering, temperature programmed desorption, and atomic force microscopy to study the interface composition and thermal stability of epitaxial strontium titanate thin films grown by molecular-beam epitaxy on Si (001). The composition of the interface between the film and the substrate was found to be very sensitive to the recrystallization temperature used during growth, varying from a strontium silicate phase when the recrystallization temperature is low to a Ti-rich phase for a higher recrystallization temperature. The films are stable towards annealing in vacuum up to {approx}550 deg.C, where SrO desorption begins and the initially flat film starts to roughen. Significant film disintegration occurs at 850 deg.C, and is accompanied by SiO and SrO desorption, pinhole formation, and finally titanium diffusion into the silicon bulk.

Goncharova, L. V.; Starodub, D. G.; Garfunkel, E.; Gustafsson, T.; Vaithyanathan, V.; Lettieri, J.; Schlom, D. G. [Department of Physics and Astronomy, and Laboratory for Surface Modification, Rutgers University, Piscataway, New Jersey 08854 (United States); Department of Chemistry and Chemical Biology, and Laboratory for Surface Modification, Rutgers University, Piscataway, New Jersey 08854 (United States); Department of Physics and Astronomy, and Laboratory for Surface Modification, Rutgers University, Piscataway, New Jersey 08854 (United States); Department of Material Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2006-07-01T23:59:59.000Z

154

Optical absorption in epitaxial La{sub 1-x}Sr{sub x}FeO{sub 3} thin films  

SciTech Connect (OSTI)

We report the dependence of optical absorption on Sr concentration in La{sub 1-x}Sr{sub x}FeO{sub 3} (LSFO) (x{<=}0.4) perovskite thin films. Strained epitaxial films were deposited on SrTiO{sub 3} substrates using oxide molecular beam epitaxy. We find systematic changes in the optical absorption spectra with increasing x including a red-shift of transition energies and the increasing presence of a lower energy transition within the fundamental gap of pure LaFeO{sub 3}. These results serve as a demonstration of the complex manner in which absorption spectra can be altered in complex oxides via heterovalent A-site substitution.

Scafetta, M D.; Xie, Y. J.; Torres, M.; Spanier, J. E.; May, S. J. [Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104 (United States)] [Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104 (United States)

2013-02-25T23:59:59.000Z

155

Sharp Fe/MgO/Ge(001) epitaxial heterostructures for tunneling junctions  

SciTech Connect (OSTI)

We report on the growth of epitaxial Fe/MgO/Ge(001) heterostructures by molecular beam epitaxy. The lowest oxidation and highest sharpness of the MgO/Ge interface, corresponding to a transition layer on the order of one Ge unit cell, is obtained for room temperature growth of the MgO layer followed by annealing in a vacuum at 500 C. In these conditions, the MgO layer grows epitaxially on Ge(001) with the [110] direction parallel to the [100] direction of Ge, at variance with the cube-on-cube growth on Si(001) and GaAs(001). However, in some cases, the cube-on-cube growth mode of MgO on Ge competes with the mode involving a 45{sup o} rotation, as revealed by transmission electron microscopy and photoelectron diffraction data on MgO films grown at 300 C without postannealing, and on p-doped Ge substrates. For the Fe overlayer, in all the cases reported, room temperature growth followed by annealing up to 200 C gives rise to a sharp interface and the well-known 45{sup o} rotation of the Fe lattice with respect to the MgO lattice.

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; Gazquez Alabart, Jaume [ORNL; Varela del Arco, Maria [ORNL

2011-01-01T23:59:59.000Z

156

Molecular beam mass spectrometric characterization of biomass pyrolysis products for fuels and chemicals  

SciTech Connect (OSTI)

Converting biomass feedstocks to fuels and chemicals requires rapid characterization of the wide variety of possible feedstocks. The combination of pyrolysis molecular beam mass spectrometry (Py-MBMS) and multivariate statistical analysis offers a unique capability for characterizing these feedstocks. Herbaceous and woody biomass feedstocks that were harvested at different periods were used in this study. The pyrolysis mass spectral data were acquired in real time on the MBMS, and multivariate statistical analysis (factor analysis) was used to analyze and classify Py-MBMS data into compound classes. The effect of harvest times on the thermal conversion of these feedstocks was assessed from these data. Apart from sericea lespedeza, the influence of harvest time on the pyrolysis products of the various feedstocks was insignificant. For sericea lespedeza, samples harvested before plant defoliation were significantly different from those harvested after defoliation. The defoliated plant samples had higher carbohydrate-derived pyrolysis products than the samples obtained from the foliated plant. Additionally, char yields from the defoliated plant samples were lower than those from the foliated plant samples.

Agblevor, F.A.; Davis, M.F.; Evans, R.J. [National Renewal Energy Lab., Golden, CO (United States)

1994-12-31T23:59:59.000Z

157

Rapid characterization of lignocellulosic feedstocks for fuels and chemicals: Molecular beam mass spectrometric approach  

SciTech Connect (OSTI)

Rapid characterization of biomass feedstocks has a pivotal role in the development of biomass energy because of the large number of samples that must be analyzed due to the diversity of biomass feedstocks and the significant differences in the chemical and physical properties of these feedstocks. Several biomass feedstocks (herbaceous, woody, and agricultural residues) were screened for the effects of storage, season of harvest, geographic location, clonal, and species variation on the pyrolysis products of the feed stocks. For herbaceous species such as sericea lespedeza, the season of harvest had a significant effect on the pyrolysis products. Effects of clonal variation on the composition of hybrid poplar feedstocks was easily discerned with the molecular beam mass spectrometric analysis. The effect of geographic location on the poplar clones pyrolysis products was minimal. However in the case of switchgrass, varietal influence on the pyrolysis products was minimal, but where the plant was grown had a strong influence on the pyrolysis products of the feedstock. Significant differences because of species variation could also be shown from the pyrolysis products of various biomass feedstocks. The influence of storage time on biomass samples stored outside in the open could also be discerned from the pyrolysis products of the feedstocks. The differences noted in the pyrolysis products of the feedstocks were noted for samples which were significantly degraded during storage either through the action of microflora or weathering.

Agblevor, F.A.; Davis, M.F. [National Renewable Energy Lab., Golden, CO (United States)

1996-12-31T23:59:59.000Z

158

Free-Standing Epitaxial Graphene Shriram Shivaraman,* Robert A. Barton, Xun Yu, Jonathan Alden,  

E-Print Network [OSTI]

Free-Standing Epitaxial Graphene Shriram Shivaraman,* Robert A. Barton, Xun Yu, Jonathan Alden to produce free-standing graphene sheets from epitaxial graphene on silicon carbide (SiC) substrate. Doubly for beams under no tension. Raman spectroscopy suggests that the graphene is not chemically modified during

McEuen, Paul L.

159

Impact of Lattice Mismatch and Stoichiometry on the Structure and Bandgap of (Fe,Cr)2O3 Epitaxial Thin Films  

SciTech Connect (OSTI)

The structural properties of high-quality epitaxial (Fe1-xCrx)2O3 thin films are investigated across the composition range. Epitaxial films are deposited on a-Al2O3(0001) substrates by oxygen-plasma-assisted molecular beam epitaxy. Corundum (Fe1-xCrx)2O3 supercells relaxed by density functional theory confirm that the non-linear behavior of the bulk lattice parameters originates in the magnetic structure of the alloy films. High-resolution x-ray diffraction reveals the degree of epitaxial strain relaxation in the films, with Cr-rich films remaining partially strained to the Al2O3 substrate. For intermediate compositions, a lattice expansion and non-Poisson-like tetragonal distortion are found. Scanning transmission electron microscopy and electron energy loss spectroscopy reveal a columnar grain structure in the films, with uniform mixing of cations on the nanometer scale. Oxygen non-stoichiometry is quantified by non-Rutherford resonant elastic scattering measurements utilizing 3.04 MeV He+. Intermediate-composition films are found to be slightly over-stoichiometric, resulting in the observed lattice expansion. Cr-rich films, in contrast, appear to be slightly oxygen deficient. A model is proposed to explain these results based on the energetics of oxygen defect formation and rate of oxygen diffusion in the corundum lattice. Compressive biaxial strain is found to reduce the bandgap of epitaxial Cr2O3 relative to the bulk value. The relationships which are elucidated between epitaxial film structure and optical properties can be applied to bandgap optimization in the (Fe,Cr)2O3 system.

Kaspar, Tiffany C.; Chamberlin, Sara E.; Bowden, Mark E.; Colby, Robert J.; Shutthanandan, V.; Manandhar, Sandeep; Wang, Yong; Sushko, Petr; Chambers, Scott A.

2014-03-13T23:59:59.000Z

160

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

SciTech Connect (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

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

Engineering coercivity in epitaxially grown (110) films of DyFe 2 –YFe 2 superlattices  

Science Journals Connector (OSTI)

Molecular beam epitaxial methods have been used to growsingle crystal Laves phase DyFe 2 –YFe 2 superlattice samples with a (110) growth direction. It is shown that it is possible in principle to engineer a desired coercivity between the limits K DyFe 2 ?K??. This can be achieved by adjusting the relative thickness of the individual DyFe 2 and YFe 2 layers in multilayerfilms This novel feature is illustrated using the superlatticefilms [x?Å? DyFe 2 /(100-x)?Å? YFe 2 ]×40 with x=80 60 50 and 45. It is found that the measured coercivity is in semiquantitative agreement with a simple theoretical expression for the nucleation fields in both bilayer and multilayer compounds. However in practice exchange spring penetration into the DyFe 2 layers can set a limit to the maximum coercivity that can be achieved.

M. Sawicki; G. J. Bowden; P. A. J. de Groot; B. D. Rainford; J. M. L. Beaujour; R. C. C. Ward; M. R. Wells

2000-01-01T23:59:59.000Z

162

Optical phonon modes in InGaN/GaN dot-in-a-wire heterostructures grown by molecular beam epitaxy  

SciTech Connect (OSTI)

We report on the studies of optical phonon modes in nearly defect-free GaN nanowires embedded with intrinsic InGaN quantum dots by using oblique angle transmission infrared spectroscopy. These phonon modes are dependent on the nanowire fill-factor, doping densities of the nanowires, and the presence of InGaN dots. These factors can be applied for potential phonon based photodetectors whose spectral responses can be tailored by varying a combination of these three parameters. The optical anisotropy along the growth (c-) axis of the GaN nanowire contributes to the polarization agility of such potential photodetectors.

Titus, J.; Perera, A. G. U. [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States)] [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States); Nguyen, H. P. T.; Mi, Z. [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 2A7 (Canada)] [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 2A7 (Canada)

2013-03-25T23:59:59.000Z

163

IVVI compound midinfrared high-reflectivity mirrors and vertical-cavity surface-emitting lasers grown by molecular-beam epitaxy  

E-Print Network [OSTI]

band extrema. Quantum confinement does not lift the degeneracy in edge-emitting QW devices, since the four valleys remain symmetric for the 100 growth that must be employed to allow for the cleaving to other III­V and II­VI semiconductors with the same energy gaps.12 We point out in this letter that lead

McCann, Patrick

164

Field-effect transistors on molecular beam epitaxy GaP Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511  

E-Print Network [OSTI]

photocorrosion in aqueous solu- tions, a property desirable for devices in medical and envi- ronmental prior light-emitting diode work and the low cost of high-quality substrates. The most preva- lent growth

Woodall, Jerry M.

165

Electrical characteristics of the CdTe-n-CdHgTe structure fabricated in a single molecular-beam epitaxy process  

SciTech Connect (OSTI)

An extraordinary shape of the capacitance-voltage characteristics of CdTe-CdHgTe structures has been detected; these characteristics include a specific 'hump' in the inversion region, the height of which increased severalfold under illumination. Additional measurements using an optical probe, measurements of current-voltage characteristics, and an analysis of the energy-band diagram of the structure showed the following. CdTe, in contrast to CdHgTe, is a p-type semiconductor with an acceptor concentration of 1 x 10{sup 16} cm{sup -3}; there is a hole inversion layer in CdHgTe at the boundary with CdTe, which causes the 'hump'; and the barrier height for holes at the CdTe-Cd{sub 0.43}Hg{sub 0.57}Te interface was determined as 0.13 eV.

Mashukov, Yu. P., E-mail: dr_mashukov@mail.ru; Mikhailov, N. N.; Vasilyev, V. V. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2010-09-15T23:59:59.000Z

166

Gas-source molecular beam epitaxial growth and characterization of the (Al,In,Ga)NP/GaP material system and Its applications to light-emitting diodes  

E-Print Network [OSTI]

T.P. , IEE Proceedings-Optoelectronics 144, 1 (1997). Kishof Energy (BTS) and the Optoelectronics Industry Developmentin semiconductor optoelectronics in recent years. Within two

Odnoblyudov, Vladimir

2006-01-01T23:59:59.000Z

167

High-resolution imaging of velocity-controlled molecular collisions using counterpropagating beams  

E-Print Network [OSTI]

We present ultrahigh-resolution measurements of state-to-state inelastic differential cross sections for NO-Ne and NO-Ar collisions, obtained by combining the Stark deceleration and velocity map imaging techniques. We show that for counterpropagating crossed beam geometries, the effect of the velocity spreads of the reagent beams on the angular resolution of the images is minimized. Futhermore, the counterpropagating geometry results in images that are symmetric with respect to the relative velocity vector. This allows for the use of inverse Abel transformation methods that enhance the resolution further. State-resolved diffraction oscillations in the differential cross sections are measured with an angular resolution approaching 0.3$^\\circ$. Distinct structures observed in the cross sections gauge the quality of recent \\emph{ab initio} potential energy surfaces for NO-rare gas atom collisions with unprecedented precision.

Vogels, Sjoerd N; von Zastrow, Alexander; Groenenboom, Gerrit C; van der Avoird, Ad; van de Meerakker, Sebastiaan Y T

2014-01-01T23:59:59.000Z

168

Big-Data RHEED analysis for understanding epitaxial film growth processes  

SciTech Connect (OSTI)

Reflection high energy electron diffraction (RHEED) has by now become a standard tool for in-situ monitoring of film growth by pulsed laser deposition and molecular beam epitaxy. Yet despite the widespread adoption and wealth of information in RHEED image, most applications are limited to observing intensity oscillations of the specular spot, and much additional information on growth is discarded. With ease of data acquisition and increased computation speeds, statistical methods to rapidly mine the dataset are now feasible. Here, we develop such an approach to the analysis of the fundamental growth processes through multivariate statistical analysis of RHEED image sequence. This approach is illustrated for growth of LaxCa1-xMnO3 films grown on etched (001) SrTiO3 substrates, but is universal. The multivariate methods including principal component analysis and k-means clustering provide insight into the relevant behaviors, the timing and nature of a disordered to ordered growth change, and highlight statistically significant patterns. Fourier analysis yields the harmonic components of the signal and allows separation of the relevant components and baselines, isolating the assymetric nature of the step density function and the transmission spots from the imperfect layer-by-layer (LBL) growth. These studies show the promise of big data approaches to obtaining more insight into film properties during and after epitaxial film growth. Furthermore, these studies open the pathway to use forward prediction methods to potentially allow significantly more control over growth process and hence final film quality.

Vasudevan, Rama K [ORNL; Tselev, Alexander [ORNL; Baddorf, Arthur P [ORNL; Kalinin, Sergei V [ORNL

2014-01-01T23:59:59.000Z

169

Energy band alignment of atomic layer deposited HfO{sub 2} oxide film on epitaxial (100)Ge, (110)Ge, and (111)Ge layers  

SciTech Connect (OSTI)

Crystallographically oriented epitaxial Ge layers were grown on (100), (110), and (111)A GaAs substrates by in situ growth process using two separate molecular beam epitaxy chambers. The band alignment properties of atomic layer hafnium oxide (HfO{sub 2}) film deposited on crystallographically oriented epitaxial Ge were investigated using x-ray photoelectron spectroscopy (XPS). Valence band offset, {Delta}E{sub v} values of HfO{sub 2} relative to (100)Ge, (110)Ge, and (111)Ge orientations were 2.8 eV, 2.28 eV, and 2.5 eV, respectively. Using XPS data, variation in valence band offset, {Delta}E{sub V}(100)Ge>{Delta}E{sub V}(111)Ge>{Delta}E{sub V}(110)Ge, was obtained related to Ge orientation. Also, the conduction band offset, {Delta}E{sub c} relation, {Delta}E{sub c}(110)Ge>{Delta}E{sub c}(111)Ge>{Delta}E{sub c}(100)Ge related to Ge orientations was obtained using the measured bandgap of HfO{sub 2} on each orientation and with the Ge bandgap of 0.67 eV. These band offset parameters for carrier confinement would offer an important guidance to design Ge-based p- and n-channel metal-oxide field-effect transistor for low-power application.

Hudait, Mantu K.; Zhu Yan [Advanced Devices and Sustainable Energy Laboratory (ADSEL), Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)

2013-03-21T23:59:59.000Z

170

Momentum imaging spectrometer for molecular fragmentation dynamics induced by pulsed electron beam  

SciTech Connect (OSTI)

A momentum imaging spectrometer has been built for studying the electron impact molecular fragmentation dynamics. The setup consists of a pulsed electron gun and a time of flight system as well as a two-dimensional time and position sensitive multi-hit detector. The charged fragments with kinetic energy up to 10 eV can be detected in 4? solid angles and their three-dimensional momentum vectors can be reconstructed. The apparatus is tested by electron impact ionization of Ar and dissociative ionization of CO{sub 2}. By analyzing the ion-ion coincidence spectra, the complete and incomplete Coulomb fragmentation channels for CO{sub 2}{sup 2+} and CO{sub 2}{sup 3+} are identified. The kinetic energy release (KER) and angular correlation for the two-body breakup channel CO{sub 2}{sup 2+*}? O{sup +}+ CO{sup +} are reported. The peak value of total KER is found to be 6.8 eV which is consistent with the previous photoion-photoion coincidence studies, and the correlation angle of O{sup +} and CO{sup +} is also explicitly determined to be 172.5°.

Wang, EnLiang; Shan, Xu; Shi, YuFeng; Tang, YaGuo; Chen, XiangJun [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2013-12-15T23:59:59.000Z

171

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

SciTech Connect (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

172

Measurement of the Zero-Field Hyperfine Structure of a Single Vibration-Rotation Level of Na2 by a Laser-Fluorescence Molecular-Beam-Resonance Technique  

Science Journals Connector (OSTI)

By replacing the A and B magnets of the conventional molecular-beam-resonance technique with laser optical-pumping regions, we have developed a method for the observation of hfs in a single molecular-vibration-rotation level of arbitrary J. We obtain for the electric quadrupole and spin-rotation constants of the X?g1+, v??=0, J??=28 level of Na2: eqQ=-463.7±0.9 kHz; |c|=0.17±0.03 kHz. We also report the first observation of a spin-rotation transition.

S. D. Rosner; R. A. Holt; T. D. Gaily

1975-09-22T23:59:59.000Z

173

In-situ imaging of the nucleation and growth of epitaxial anatase TiO2(001) films on SrTiO3(001)  

SciTech Connect (OSTI)

The growth of TiO2 anatase films on Nb doped SrTiO3(001) by oxygen-assisted molecular beam epitaxy has been studied in-situ by scanning tunneling microscopy. We show that the initial growth follows the Stranski-Krastanov mode, where islands form on top of a wetting layer consisting of two monolayers (ML) of TiO2. The epitaxial islands subsequently nucleate and coalescence into large commonly-oriented crystallites. The (4x4) reconstruction observed by reflection high-energy electron diffraction (RHEED) is shown to result from the coexistence of individual (4x1) and (1x4) reconstructions present on different crystallite surfaces. The anatase grows in units of bilayers, resulting in a step height of 2 ML (~0.5 nm). This result explains the fact that the measured period of the RHEED specular-beam intensity oscillations corresponds to the time required for deposition of 2 ML. Ar ion sputtering and UHV annealing results in a transformation to coexisting (4x1) and (1x4) reconstructed terraces on individual crystallites, as commonly observed by ex-situ STM studies.

Du, Yingge; Kim, Dong Jun; Kaspar, Tiffany C.; Chamberlin, Sara E.; Lyubinetsky, Igor; Chambers, Scott A.

2012-09-30T23:59:59.000Z

174

Versatile piezoelectric pulsed molecular beam source for gaseous compounds and organic molecules with femtomole accuracy for UHV and surface science applications  

SciTech Connect (OSTI)

This note describes the construction of a piezoelectric pulsed molecular beam source based upon a design presented in an earlier work [D. Proch and T. Trickl, Rev. Sci. Instrum. 60, 713 (1988)]. The design features significant modifications that permit the determination of the number of molecules in a beam pulse with an accuracy of 1x10{sup 11} molecules per pulse. The 21 cm long plunger-nozzle setup allows the molecules to be brought to any point of the UHV chamber with very high intensity. Furthermore, besides typical gaseous compounds, also smaller organic molecules with a vapor pressure higher than 0.1 mbar at room temperature may serve as feed material. This makes the new design suitable for various applications in chemical and surface science studies.

Schiesser, Alexander; Schaefer, Rolf [Eduard-Zintl-Institut fuer Anorganische und Physikalische Chemie, Technische Universitaet Darmstadt, Petersenstrasse 20, 64287 Darmstadt (Germany)

2009-08-15T23:59:59.000Z

175

Epitaxial Graphene on Cu(111)  

Science Journals Connector (OSTI)

Epitaxial Graphene on Cu(111) ... The growth of graphene on single crystal Cu(111) has been achieved by thermal decomposition of ethylene in an ultrahigh vacuum chamber for the first time. ... The structural and electronic properties of graphene on Cu(111) have been investigated by scanning tunneling microscopy and spectroscopy. ...

Li Gao; Jeffrey R. Guest; Nathan P. Guisinger

2010-08-02T23:59:59.000Z

176

Photodiode characteristics and band alignment parameters of epitaxial Al0.5Ga0.5P  

E-Print Network [OSTI]

Photodiode characteristics and band alignment parameters of epitaxial Al0.5Ga0.5P An Chen1,a-bandgap semiconductor AlxGa1-xP is a promising material candidate for low-noise photodiodes in blue/UV spectrum. Photodiodes were fabricated on Al0.5Ga0.5P epitaxial layer grown lattice matched on GaP substrate by molecular

Woodall, Jerry M.

177

Comparative optical study of epitaxial InGaAs quantum rods grown with As{sub 2} and As{sub 4} sources  

SciTech Connect (OSTI)

Photoreflectance and photoluminescence (PL) spectroscopies are used to examine the optical properties and electronic structure of InGaAs quantum rods (QRs), embedded within InGaAs quantum well (QW). The nanostructures studied were grown by molecular beam epitaxy using As{sub 2} or As{sub 4} sources. The impact of As source on spectral features associated with interband optical transitions in the QRs and the surrounding QW are demonstrated. A red shift of the QR- and a blue shift of the QW-related optical transitions, along with a significant increase in PL intensity, have been observed if an As{sub 4} source is used. The changes in optical properties are attributed mainly to carrier confinement effects caused by variation of In content contrast between the QR material and the surrounding well.

Nedzinskas, Ram?nas; ?echavi?ius, Bronislovas; Kavaliauskas, Julius; Karpus, Vytautas; Valušis, Gintaras [Semiconductor Physics Institute, Center for Physical Sciences and Technology, A. Goštauto 11, LT-01108 Vilnius (Lithuania); Li, Lianhe; Khanna, Suraj P.; Linfield, Edmund H. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom)

2013-12-04T23:59:59.000Z

178

Epitaxial growth and characterization of Ce{sub 1{minus}x}Zr{sub x}O{sub 2} thin films  

SciTech Connect (OSTI)

Epitaxial films of mixed Ce{sub 1{minus}x}Zr{sub x}O{sub 2}(001) oxides with x{le}0.3 have been grown on SrTiO{sub 3}(001) by oxygen-plasma-assisted molecular beam epitaxy. The film growth at 600 {degree}C is predominantly nucleation and growth of three-dimensional islands. The films become much smoother after rapid thermal annealing at 700 {degree}C for 30 s in the oxygen plasma. High-energy ion channeling reveals that Zr atoms substitutionally incorporate at cation sites in the CeO{sub 2} lattice for all doping levels, leading to Ce{sub 1{minus}x}Zr{sub x}O{sub 2} solid solutions. Analysis of Zr 3d and Ce 3d core-level binding energies shows that the oxidation state of both Zr and Ce is +4. Lattice distortion induced by incorporation of Zr in the CeO{sub 2} lattice becomes prevalent for high doping levels and surface roughen accordingly. {copyright} {ital 1999 American Vacuum Society.}

Gao, Y.; Herman, G.S.; Thevuthasan, S.; Peden, C.H.; Chambers, S.A. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)] [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

1999-05-01T23:59:59.000Z

179

Band-Gap Reduction and Dopant Interaction in Epitaxial La,Cr Co-doped SrTiO3 Thin Films  

SciTech Connect (OSTI)

We show that by co-doping SrTiO3 (STO) epitaxial thin films with equal amounts of La and Cr it is possible to produce films with an optical band gap ~0.9 eV lower than that of undoped STO. Sr1-xLaxTi1-xCrxO3 thin films were deposited by molecular beam epitaxy and characterized using x-ray photoelectron spectroscopy and x-ray absorption near-edge spectroscopy to show that the Cr dopants are almost exclusively in the Cr3+ oxidation state. Extended x-ray absorption fine structure measurements and theoretical modeling suggest that it is thermodynamically preferred for La and Cr dopants to occupy nearest neighbor A- and B-sites in the lattice. Transport measurements show that the material exhibits variable-range hopping conductivity with high resistivity. These results create new opportunities for the use of doped STO films in photovoltaic and photocatalytic applications.

Comes, Ryan B.; Sushko, Petr; Heald, Steve M.; Colby, Robert J.; Bowden, Mark E.; Chambers, Scott A.

2014-12-03T23:59:59.000Z

180

Photodiode characteristics and band alignment parameters of epitaxial Al{sub 0.5}Ga{sub 0.5}P  

SciTech Connect (OSTI)

Wide-bandgap semiconductor Al{sub x}Ga{sub 1-x}P is a promising material candidate for low-noise photodiodes in blue/UV spectrum. Photodiodes were fabricated on Al{sub 0.5}Ga{sub 0.5}P epitaxial layer grown lattice matched on GaP substrate by molecular beam epitaxy. Although quantum efficiency is low for standard p-i-n photodiode due to inadvertent photon absorption in the top p-layer, it can be significantly improved by opening a recessed window in the top p-layer or by using a Schottky junction photodiode structure. Al{sub 0.5}Ga{sub 0.5}P band alignment parameters can be extrapolated from the current-voltage characteristics of Al{sub 0.5}Ga{sub 0.5}P Schottky junctions. The bandgap of Al{sub 0.5}Ga{sub 0.5}P was measured to be 2.38 eV.

Chen An [Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511 (United States); Woodall, Jerry M. [School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2009-01-12T23:59:59.000Z

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

Epitaxial Single Crystal Nanostructures for Batteries & PVs ...  

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

Electrode Channel Flow DEMS Cell Sulfur@Carbon Cathodes for Lithium Sulfur Batteries Better Ham & Cheese: Enhanced Anodes and Cathodes for Fuel Cells Epitaxial Single...

182

THz Carrier Dynamics in Epitaxial Graphene  

Science Journals Connector (OSTI)

Ultrafast optical pump/THz-probe spectroscopy is used to measure the conductivity recovery dynamics in epitaxial graphene. The observed dynamics are insensitive to probe frequency,...

Divin, Charles J; Sun, Dong; Berger, Claire; de Heer, Walt; First, P N; Norris, Theodore B

183

Ferroelectric and ferromagnetic properties of epitaxial BiFeO{sub 3}-BiMnO{sub 3} films on ion-beam-assisted deposited TiN buffered flexible Hastelloy  

SciTech Connect (OSTI)

Growth of multifunctional thin films on flexible substrates is of great technological significance since such a platform is needed for flexible electronics. In this study, we report the growth of biaxially aligned (BiFeO{sub 3}){sub 0.5}:(BiMnO{sub 3}){sub 0.5} [BFO-BMO] films on polycrystalline Hastelloy by using a biaxially aligned TiN as a seed layer deposited by ion-beam-assisted deposited and a La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) as a buffer layer deposited by pulsed laser deposition. The LSMO is used not only as a buffer layer but also as the bottom electrode of the BFO-BMO films. X-ray diffraction showed that the BFO-BMO films are biaxially oriented along both in-plane and out-of-plane directions. The BFO-BMO films on flexible metal substrates showed a polarization of 22.9??C/cm{sup 2}. The magnetization of the BFO-BMO/LSMO is 62?emu/cc at room temperature.

Xiong, J., E-mail: jiexiong@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Los Alamos National Laboratory, Center for Integrated Nanotechnologies, Division of Materials Physics and Applications, Los Alamos, New Mexico 87545 (United States); Matias, V.; Jia, Q. X. [Los Alamos National Laboratory, Center for Integrated Nanotechnologies, Division of Materials Physics and Applications, Los Alamos, New Mexico 87545 (United States); Tao, B. W.; Li, Y. R. [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2014-05-07T23:59:59.000Z

184

Growth of Epitaxial gamma-Al2O3 Films on Rigid Single-Crystal Ceramic Substrates and Flexible, Single-Crystal-Like Metallic Substrates by Pulsed Laser Deposition  

SciTech Connect (OSTI)

Epitaxial -Al2O3 thin films were grown on diverse substrates using pulsed laser deposition. The high quality of epitaxial growth and cubic structure of -Al2O3 films was confirmed by x-ray diffraction. SrTiO3 and MgO single crystal substrates were used to optimize the growth conditions for epitaxial -Al2O3 film. Under the optimized conditions, epitaxial -Al2O3 thin films were grown on flexible, single-crystal-like, metallic templates. These included untextured Hastelloy substrates with a biaxially textured MgO layer deposited using ion-beam-assisted-deposition and biaxially textured Ni-W metallic tapes with epitaxially grown and a biaxially textured, MgO buffer layer. These biaxially textured, -Al2O3 films on flexible, single-crystal-like substrates are promising for subsequent epitaxial growth of various complex oxide films used for electrical, magnetic and electronic device applications.

Shin, Junsoo [ORNL; Goyal, Amit [ORNL; Wee, Sung Hun [ORNL

2009-01-01T23:59:59.000Z

185

Quasibound levels and shape resonances of /sup 39/K/sub 2/(B /sup 1/Pi/sub u/) crossed laser-molecular beam studies and analytical interpretation  

SciTech Connect (OSTI)

Quasibound levels and shape resonances in the (B /sup 1/Pi/sub u/ -X /sup 1/..sigma../sup +//sub g/) band system of /sup 39/K/sub 2/ have been recorded by crossed laser-molecular beam techniques. Using optical--optical double resonance, individual rovibrational levels (v'' = 15--18, J'' = 3--25) of the K/sub 2/ state are prepared by Franck--Condon pumping (FCP) in a supersonic nozzle beam. Excitation into quasibound levels below and above the (B /sup 1/Pi/sub u/) state barrier is detected as molecular and atomic (K4 /sup 2/P/sub 3//sub ///sub 2/..-->..4 /sup 2/S/sub 1//sub ///sub 2/ only) fluorescence. The resonance transition frequencies and shapes are measured and the results are used (a) to determine the scattering resonance energies, widths, and lifetimes; (b) to compare them with values obtained by a ''maximum internal amplitude'' approach (R. J. LeRoy and R. B. Bernstein, J. Chem. Phys. 54, 5114 (1971)); and (c) to check the agreement with exact calculations of the B state potential using the ''inverted perturbation approach (IPA).'' The bound and quasibound part of the B /sup 1/Pi/sub u/ state including the locus (R = 8.08 +- 0.05 A) of the barrier maximum (298 +- 8 cm/sup -1/ above the adiabatic dissociation limit) is found in excellent agreement with previous results. The shape resonances are not highly sensitive to the long-range interatomic forces, here the repulsive dipole--dipole resonance interaction.

Heinze, J.; Kowalczyk, P.; Engelke, F.

1988-09-15T23:59:59.000Z

186

Low interfacial trap density and sub-nm equivalent oxide thickness in In{sub 0.53}Ga{sub 0.47}As (001) metal-oxide-semiconductor devices using molecular beam deposited HfO{sub 2}/Al{sub 2}O{sub 3} as gate dielectrics  

SciTech Connect (OSTI)

We investigated the passivation of In{sub 0.53}Ga{sub 0.47}As (001) surface by molecular beam epitaxy techniques. After growth of strained In{sub 0.53}Ga{sub 0.47}As on InP (001) substrate, HfO{sub 2}/Al{sub 2}O{sub 3} high-{kappa} oxide stacks have been deposited in-situ after surface reconstruction engineering. Excellent capacitance-voltage characteristics have been demonstrated along with low gate leakage currents. The interfacial density of states (D{sub it}) of the Al{sub 2}O{sub 3}/In{sub 0.53}Ga{sub 0.47}As interface have been revealed by conductance measurement, indicating a downward D{sub it} profile from the energy close to the valence band (medium 10{sup 12} cm{sup -2}eV{sup -1}) towards that close to the conduction band (10{sup 11} cm{sup -2}eV{sup -1}). The low D{sub it}'s are in good agreement with the high Fermi-level movement efficiency of greater than 80%. Moreover, excellent scalability of the HfO{sub 2} has been demonstrated as evidenced by the good dependence of capacitance oxide thickness on the HfO{sub 2} thickness (dielectric constant of HfO{sub 2}{approx}20) and the remained low D{sub it}'s due to the thin Al{sub 2}O{sub 3} passivation layer. The sample with HfO{sub 2} (3.4 nm)/Al{sub 2}O{sub 3} (1.2 nm) as the gate dielectrics has exhibited an equivalent oxide thickness of {approx}0.93 nm.

Chu, L. K. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Katholieke Universiteit Leuven, 3001 Leuven (Belgium); Merckling, C.; Dekoster, J.; Caymax, M. [Interuniversity Microelectronics Center (IMEC vzw), 3001 Leuven (Belgium); Alian, A.; Heyns, M. [Katholieke Universiteit Leuven, 3001 Leuven (Belgium); Interuniversity Microelectronics Center (IMEC vzw), 3001 Leuven (Belgium); Kwo, J. [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China); Hong, M. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

2011-07-25T23:59:59.000Z

187

Ion beam processing of advanced electronic materials  

SciTech Connect (OSTI)

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

188

Beam History  

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

189

Construção e caracterização de célula solar tipo barreira Schottky CdTe/Al.  

E-Print Network [OSTI]

??In this work the techniques of hot wall epitaxy (HWE) and molecular beam epitaxy (MBE) on thin films of CdTe (cadmium telluride) were used in… (more)

Denis Rafael de Oliveira Pereira

2011-01-01T23:59:59.000Z

190

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

SciTech Connect (OSTI)

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

191

Enhanced production of runaway electrons during electron cyclotron resonance heating and in the presence of supersonic molecular beam injection in the HL-2A tokamak  

SciTech Connect (OSTI)

In the present paper, it is reported that a large production of runaway electrons has been observed during the flattop phase of electron cyclotron resonance heating (ECRH) discharges and in the presence of supersonic molecular beam injection (SMBI) in the HuanLiuqi-2A (commonly referred to as HL-2A) [Q. W. Yang, Nucl. Fusion 47, S635 (2007)] tokamak. For the set of discharges carried out in the present experiment, the ranges of ECRH power and plasma electron density are 0.8-1.0 MW and (3.0-4.0)x10{sup 19} m{sup -3}, respectively. A large number of superthermal electrons are produced through the avalanche effect [A. Lazaros, Phys. Plasmas 8, 1263 (2001)] during ECRH. The loop voltage increase due to SMBI gives rise to a decline in the critical runaway energy, which leads to that many superthermal electrons could be converted into runaway region. Therefore, this phenomenon may come from the synergetic effects of ECRH and SMBI. That is, the superthermal electrons created by ECRH are accelerated into runaway regime via the Dreicer process which is triggered by SMBI. The experimental results are in well agreement with the calculational ones based on the superthermal electron avalanche effect and the Dreicer runaway theory.

Zhang, Y. P.; Liu, Yi; Yang, J. W.; Song, X. Y.; Yuan, G. L.; Zhou, J.; Yao, L. H.; Feng, B. B.; Li, X.; Yang, Q. W.; Duan, X. R.; Pan, C. H.; Liu, Y. [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041 (China)

2010-07-15T23:59:59.000Z

192

Characterization of isothermal vapor phase epitaxial (Hg,Cd)Te  

Science Journals Connector (OSTI)

We report on the characterization of mercury cadmium telluride (Hg 1?x Cd x Te) film grown by the isothermal vapor phase epitaxial method (ISOVPE) and on the surface conversion of bulk Hg 1?xCd x Te to larger bandgap material. The crystal perfection is evaluated using defect etching electron beam and electrolyte electroreflectance (EBER and EER) and Rutherford backscattering spectrometry (RBS). Hall measurements are used to measure carrier densities and mobilities. Surface concentrations and concentration profiles are measured for the ISOVPE grown layers by transmission Fourier transform infrared spectroscopy (FTIR) and electron?probe microanalysis (EPMA) to establish quantitative informations about composition control. Metal–insulator?semiconductor (MIS) structures were made and the properties important to device performance such as compositional uniformity storage time and carrier concentration are measured. The ISOVPE layers are compared in quality to films grown by other methods and show promise for MIS devices.

S. B. Lee; L. K. Magel; M. F. S. Tang; D. A. Stevenson; J. H. Tregilgas; M. W. Goodwin; R. L. Strong

1990-01-01T23:59:59.000Z

193

Magnetic properties of epitaxial Co-doped anatase TiO2 thin films with excellent structural quality  

SciTech Connect (OSTI)

The heteroepitaxy of Co-doped anatase TiO2 on LaAlO3(001) has been refined with the goal of determining the relationship between structural quality and magnetic ordering. By significantly reducing the deposition rate and substrate temperature, well-ordered Co:TiO2 films with unprecedented crystalline quality were obtained by oxygen-plasma-assisted molecular beam epitaxy, as characterized by x-ray diffraction. These films exhibit uniform Co doping, with no evidence of Co segregation or secondary phases throughout the film depth or on the surface. Despite the improvement in crystalline quality and Co distribution, the films exhibit negligible ferromagnetism, with saturation moments of only ~0.1 ?B/Co. This loss of ferromagnetism is in stark contrast to faster-grown Co:TiO2 films, where a higher growth rate and substrate temperature typically result in lower crystalline quality, a highly non-uniform Co distribution, and average saturation moments of ~1.2 ?B/Co. The presence of ferromagnetism in faster-grown Co:TiO2 does not appear to arise from intrinsic point defects present in the bulk material, such as charge-compensating oxygen vacancies, but is instead attributed to the presence of extended structural defects.

Kaspar, Tiffany C.; Droubay, Timothy C.; McCready, David E.; Nachimuthu, Ponnusamy; Heald, Steve M.; Wang, Chong M.; Lea, Alan S.; Shutthanandan, V.; Chambers, Scott A.; Toney, Michael F.

2006-07-26T23:59:59.000Z

194

Sb surface segregation during epitaxial growth of SiGe heterostructures: The effects of Ge composition and biaxial stress  

Science Journals Connector (OSTI)

Antimony is the most widely used n-type dopant for Si molecular-beam epitaxy (MBE). However, because of surface segregation during growth, the control of doping profiles remains difficult. The case of Si/Si1-xGex heterostructures is complicated by the existence of stresses, which may affect both the thermodynamics and kinetics of segregation. In this study, we analyze the segregation of Sb resulting from the MBE growth of Si1-xGex/Si(100) heterostructures using secondary ion mass spectrometry as a function of (i) growth temperature (200 °C<~T°<~550 °C), (ii) germanium content (0<~x<~0.2), and (iii) stresses (compressively strained and relaxed layers). We show that Sb segregation: (i) increases with temperature, (ii) increases with Ge content in biaxially compressed layers, (iii) decreases with Ge content in relaxed layers. The temperature variation indicates that Sb surface segregation during growth is kinetically controlled. The contrasting behaviors observed as a function of Ge content in stressed and relaxed layers can thus be explained by a decrease of the segregation enthalpy induced by Ge addition and an increase of near-surface diffusion in stressed layers.

A. Portavoce; I. Berbezier; P. Gas; A. Ronda

2004-04-15T23:59:59.000Z

195

Epitaxial growth of (001)-oriented Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} thin films on a-plane sapphire with an MgO/ZnO bridge layer  

SciTech Connect (OSTI)

High quality (001)-oriented Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BST) thin films have been grown on a-plane sapphire (1120) by rf magnetron sputtering using a double bridge layer consisting of (0001)-oriented ZnO (50 nm) and (001)-oriented MgO (10 nm) prepared by plasma-assisted molecular beam epitaxy. X-ray diffraction revealed the formation of three sets of in-plane BST domains, offset from one another by 30 deg., which is consistent with the in-plane symmetry of the MgO layer observed by in situ reflective high electron energy diffraction. The in-plane epitaxial relationship of BST, MgO, and ZnO has been determined to be BST [110]//MgO [110]//ZnO [1120] and BST [110]/MgO [110]//ZnO [1100]. Capacitance-voltage measurements performed on BST coplanar interdigitated capacitor structures revealed a high dielectric tunability of up to 84% at 1 MHz.

Xiao Bo; Liu Hongrui; Avrutin, Vitaliy; Leach, Jacob H.; Rowe, Emmanuel; Liu Huiyong; Oezguer, Uemit; Morkoc, Hadis [Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Chang, W.; Alldredge, L. M. B.; Kirchoefer, S. W.; Pond, J. M. [Naval Research Laboratory Washington, Washington, DC 20375 (United States)

2009-11-23T23:59:59.000Z

196

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

SciTech Connect (OSTI)

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 C.; Kaspar, Tiffany C.; Punnoose, Alex; Hays, Jason; Chambers, Scott A.

2006-08-01T23:59:59.000Z

197

Beam History  

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

198

Molecular Foundry  

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

199

Substrate-Induced Band-Gap Opening in Epitaxial Graphene  

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

200

Structure, Magnetism and Conductivity in Epitaxial Ti-doped ...  

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

Magnetism and Conductivity in Epitaxial Ti-doped -Fe2O3 Hematite: Experiment and density functional theory Structure, Magnetism and Conductivity in Epitaxial Ti-doped -Fe2O3...

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.


201

Douglas H. Lowndes | ornl.gov  

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

energetic beam-assisted film growth and doping (laser molecular-beam epitaxy and ion-beam-assisted deposition); the enhancement of physical properties using superlattice, quantum...

202

Epitaxial graphene on silicon carbide: Introduction to structured graphene  

E-Print Network [OSTI]

Epitaxial graphene on silicon carbide: Introduction to structured graphene Ming Ruan 1 , Yike Hu 1, France Abstract We present an introduction to the rapidly growing field of epitaxial graphene on silicon present, highly evolved state. The potential of epitaxial graphene as a new electronic material is now

Paris-Sud XI, Université de

203

Chemical vapor deposition of epitaxial silicon  

DOE Patents [OSTI]

A single chamber continuous chemical vapor deposition (CVD) reactor is described for depositing continuously on flat substrates, for example, epitaxial layers of semiconductor materials. The single chamber reactor is formed into three separate zones by baffles or tubes carrying chemical source material and a carrier gas in one gas stream and hydrogen gas in the other stream without interaction while the wafers are heated to deposition temperature. Diffusion of the two gas streams on heated wafers effects the epitaxial deposition in the intermediate zone and the wafers are cooled in the final zone by coolant gases. A CVD reactor for batch processing is also described embodying the deposition principles of the continuous reactor.

Berkman, Samuel (Florham Park, NJ)

1984-01-01T23:59:59.000Z

204

PHOTOELECTRON PHOTOION MOLECULAR BEAM SPECTROSCOPY  

E-Print Network [OSTI]

that are compatible with the UHV environments necessary toare not compatible with this UHV environment, such as, gasespressure sample region to the UHV region of the radiation

Trevor, Dennis J.

2010-01-01T23:59:59.000Z

205

Electrostatic transfer of epitaxial graphene to glass.  

SciTech Connect (OSTI)

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

206

Junction Transport in Epitaxial Film Silicon Heterojunction Solar Cells: Preprint  

SciTech Connect (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

207

Wafer bonded epitaxial templates for silicon heterostructures  

DOE Patents [OSTI]

A heterostructure device layer is epitaxially grown on a virtual substrate, such as an InP/InGaAs/InP double heterostructure. A device substrate and a handle substrate form the virtual substrate. The device substrate is bonded to the handle substrate and is composed of a material suitable for fabrication of optoelectronic devices. The handle substrate is composed of a material suitable for providing mechanical support. The mechanical strength of the device and handle substrates is improved and the device substrate is thinned to leave a single-crystal film on the virtual substrate such as by exfoliation of a device film from the device substrate. An upper portion of the device film exfoliated from the device substrate is removed to provide a smoother and less defect prone surface for an optoelectronic device. A heterostructure is epitaxially grown on the smoothed surface in which an optoelectronic device may be fabricated.

Atwater, Jr., Harry A. (So. Pasadena, CA); Zahler, James M. (Pasadena, CA); Morral, Anna Fontcubera I (Paris, FR)

2008-03-11T23:59:59.000Z

208

Substrate-Induced Band-Gap Opening in Epitaxial Graphene  

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

209

ORIGINAL PAPER Epitaxial Stabilization of Face Selective Catalysts  

E-Print Network [OSTI]

with changes in catalytic performance (activity and selec- tivity), using the hydrogenation of acrolein combinations. Keywords Epitaxy Á Perovskite Á Platinum Á Heterogeneous catalysis Á Hydrogenation Á Acrolein

Marks, Laurence D.

210

Ultrafast THz Studies of Few-Layer Epitaxial Graphene  

Science Journals Connector (OSTI)

We report the broadband optical conductivity and ultrafast THz dynamics of few-layer epitaxial graphene, revealing electrodynamics consistent with a dense Dirac electron plasma and a...

Choi, Hyunyong; Borondics, Ferenc; Siegel, David A; Zhou, Shuyun; Martin, Michael C; Lanzara, Alessandra; Kaindl, Robert A

211

Ultra-low contact resistance at an epitaxial metal/oxide heterojunctio...  

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

Ultra-low contact resistance at an epitaxial metaloxide heterojunction through interstitial site doping. Ultra-low contact resistance at an epitaxial metaloxide heterojunction...

212

Crossed Molecular Beams Study on the Formation of Vinylacetylene in Titan's Atmosphere Fangtong Zhang, Yong Seol Kim, and Ralf I. Kaiser*  

E-Print Network [OSTI]

), was investigated at a collision energy of 20.6 ( 0.4 kJ mol-1 utilizing the crossed-beams technique. Combined such as Titan's atmosphere via the neutral-neutral reaction of ethynyl radicals with ubiquitous ethylene and their role in the build-

Kaiser, Ralf I.

213

Investigation of epitaxial arrangement and electronic structure of a La@C82 film grown on an MoS2 surface  

Science Journals Connector (OSTI)

Molecular arrangement and electronic structure of a La@C82 film epitaxially grown on an MoS2 surface have been studied using reflection high-energy electron diffraction and electron energy-loss spectroscopy (EELS). It was revealed that La@C82 molecules form a close-packed hexagonal lattice on a cleaved face of MoS2 with the intermolecular distance of 1.13±0.03 nm. EELS of the La@C82 film in the valence excitation region indicated seven peaks coming from ???* transitions together with the ?-plasmon excitation. The absence of a distinct band gap means that the La@C82 epitaxial film is not semiconducting, but metallic or semimetallic. From the EELS result, we propose an electronic structure diagram of the La@C82 epitaxial film.

K. Iizumi, Y. Uchino, K. Ueno, A. Koma, K. Saiki, Y. Inada, K. Nagai, Y. Iwasa, and T. Mitani

2000-09-15T23:59:59.000Z

214

Studies on Biological Effects of Ion Beams on Lethality, Molecular Nature of Mutation, Mutation Rate, and Spectrum of Mutation Phenotype for Mutation Breeding in Higher Plants  

Science Journals Connector (OSTI)

......rearrangements preferably induced by car- bon ions have different molecular...mutant, suv2-1, which is defective in cell-cycle arrest in response...Rearrangement of the DNA in car- bon ion-induced mutants...mutant in Arabidopsis thaliana is defective in the DNA damage response......

Atsushi Tanaka; Naoya Shikazono; Yoshihiro Hase

2010-05-01T23:59:59.000Z

215

Epitaxial oxygen sponges as low temperature catalysts | ornl.gov  

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

216

Epitaxial-Graphene/Graphene-Oxide Junction: An Essential Step towards Epitaxial Graphene Electronics  

Science Journals Connector (OSTI)

Graphene-oxide (GO) flakes have been deposited to bridge the gap between two epitaxial-graphene electrodes to produce all-graphene devices. Electrical measurements indicate the presence of Schottky barriers at the graphene/graphene-oxide junctions, as a consequence of the band gap in GO. The barrier height is found to be about 0.7 eV, and is reduced after annealing at 180?°C, implying that the gap can be tuned by changing the degree of oxidation. A lower limit of the GO mobility was found to be 850??cm2/V?s, rivaling silicon. In situ local oxidation of patterned epitaxial graphene has been achieved.

Xiaosong Wu; Mike Sprinkle; Xuebin Li; Fan Ming; Claire Berger; Walt A. de Heer

2008-07-07T23:59:59.000Z

217

Self-doping effects in epitaxially grown graphene  

E-Print Network [OSTI]

The electronic properties of graphene, Rev. Mod. Phys. (inE?ects in Epitaxially-Grown Graphene D.A. Siegel, 1, 2 S.Y.2009) Abstract Self-doping in graphene has been studied by

Siegel, David A.

2009-01-01T23:59:59.000Z

218

Structure of Si-capped Ge/SiC/Si (001) epitaxial nanodots: Implications for quantum dot patterning  

SciTech Connect (OSTI)

Artificially ordered quantum dot (QD) arrays, where confined carriers can interact via direct exchange coupling, may create unique functionalities such as cluster qubits and spintronic bandgap systems. Development of such arrays for quantum computing requires fine control over QD size and spatial arrangement on the sub-35 nm length scale. We employ electron-beam irradiation to locally decompose ambient hydrocarbons onto a bare Si (001) surface. These carbonaceous patterns are annealed in ultra-high vacuum (UHV), forming ordered arrays of nanoscale SiC precipitates that have been suggested to template subsequent epitaxial Ge growth to form ordered QD arrays. We show that 3C-SiC nanodots form, in cube-on-cube epitaxial registry with the Si substrate. The SiC nanodots are fully relaxed by misfit dislocations and exhibit small lattice rotations with respect to the substrate. Ge overgrowth at elevated deposition temperatures, followed by Si capping, results in expulsion of the Ge from SiC template sites due to the large chemical and lattice mismatch between Ge and C. Maintaining an epitaxial, low-defectivity Si matrix around the quantum dots is important for creating reproducible electronic and spintronic coupling of states localized at the QDs.

Petz, C. W.; Floro, J. A. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Yang, D.; Levy, J. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)

2012-04-02T23:59:59.000Z

219

Steric effects in molecular adsorption  

SciTech Connect (OSTI)

The results of a molecular beam surface scattering experiment with preferentially orientated NO on Ag(111) are given. In adsorption molecules oriented with the O end towards the surface have a larger trapping probability.

Tenner, M.G.; Kuipers, E.W.; Kleyn, A.W.; Stolte, S.

1988-11-15T23:59:59.000Z

220

Molecular beam deposition of Al{sub 2}O{sub 3} on p-Ge(001)/Ge{sub 0.95}Sn{sub 0.05} heterostructure and impact of a Ge-cap interfacial layer  

SciTech Connect (OSTI)

We investigated the molecular beam deposition of Al{sub 2}O{sub 3} on Ge{sub 0.95}Sn{sub 0.05} surface with and without an ultra thin Ge cap layer in between. We first studied the atomic configuration of both Ge{sub 1-x}Sn{sub x} and Ge/Ge{sub 1-x}Sn{sub x} surfaces after deoxidation by reflection high-energy electron diffraction and resulted, respectively, in a c(4x2) and (2x1) surface reconstructions. After in situ deposition of an Al{sub 2}O{sub 3} high-{kappa} gate dielectric we evidenced using time-of-flight secondary ion mass spectroscopy analyses that Sn diffusion was at the origin of high leakage current densities in the Ge{sub 1-x}Sn{sub x}/Al{sub 2}O{sub 3} gate stack. This damage could be avoided by inserting a thin 5-nm-thick Ge cap between the oxide and the Ge{sub 1-x}Sn{sub x} layer. Finally, metal-oxide-semiconductor capacitors on the Ge capped sample showed well-behaved capacitance-voltage (C-V) characteristics with interface trap density (D{sub it}) in the range of 10{sup 12} eV{sup -1} cm{sup -2} in mid gap and higher close to the valence band edge.

Merckling, C.; Franquet, A.; Vincent, B.; Vandervorst, W.; Loo, R.; Caymax, M. [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); Shimura, Y.; Takeuchi, S.; Nakatsuka, O.; Zaima, S. [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

2011-05-09T23:59:59.000Z

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.


221

Growth of Epitaxial Thin Pd(111) Films on Pt(111) and Oxygen...  

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

Growth of Epitaxial Thin Pd(111) Films on Pt(111) and Oxygen-Terminated FeO(111) Surfaces . Growth of Epitaxial Thin Pd(111) Films on Pt(111) and Oxygen-Terminated FeO(111)...

222

Nanoscale Phase Separation In Epitaxial Cr-Mo and Cr-V Alloy...  

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

Separation In Epitaxial Cr-Mo and Cr-V Alloy Thin Films Studied Using Atom Probe Tomography: Comparison Of Nanoscale Phase Separation In Epitaxial Cr-Mo and Cr-V Alloy Thin Films...

223

Structural investigations of hydrogenated epitaxial graphene grown on 4H-SiC (0001)  

SciTech Connect (OSTI)

Structural investigations of hydrogenated epitaxial graphene grown on SiC(0001) are presented. It is shown that hydrogen plays a dual role. In addition to contributing to the well-known removal of the buffer layer, it goes between the graphene planes, resulting in an increase of the interlayer spacing to 3.6?Ŗ3.8?Å. It is explained by the intercalation of molecular hydrogen between carbon planes, which is followed by H{sub 2} dissociation, resulting in negatively charged hydrogen atoms trapped between the graphene layers, with some addition of covalent bonding to carbon atoms. Negatively charged hydrogen may be responsible for p-doping observed in hydrogenated multilayer graphene.

Tokarczyk, M.; Kowalski, G., E-mail: Grzegorz.Kowalski@fuw.edu.pl; St?pniewski, R. [Faculty of Physics, University of Warsaw, Ho?a 69, 00-681 Warsaw (Poland)] [Faculty of Physics, University of Warsaw, Ho?a 69, 00-681 Warsaw (Poland); Mo?d?onek, M.; Strupi?ski, W.; Ciepielewski, P. [Institute of Electronic Materials Technology, Wólczy?ska 133, 01-919 Warsaw (Poland)] [Institute of Electronic Materials Technology, Wólczy?ska 133, 01-919 Warsaw (Poland); Borysiuk, J. [Faculty of Physics, University of Warsaw, Ho?a 69, 00-681 Warsaw (Poland) [Faculty of Physics, University of Warsaw, Ho?a 69, 00-681 Warsaw (Poland); Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, Warsaw (Poland); Baranowski, J. M. [Faculty of Physics, University of Warsaw, Ho?a 69, 00-681 Warsaw (Poland) [Faculty of Physics, University of Warsaw, Ho?a 69, 00-681 Warsaw (Poland); Institute of Electronic Materials Technology, Wólczy?ska 133, 01-919 Warsaw (Poland)

2013-12-09T23:59:59.000Z

224

Thin crystalline silicon solar cells based on epitaxial films grown at 165C by RF PECVD  

E-Print Network [OSTI]

1 Thin crystalline silicon solar cells based on epitaxial films grown at 165°C by RF PECVD Romain temperatures. Keywords : Low temperature, epitaxy, PECVD, Si thin film, Solar cell hal-00749873,version1-25Nov shortage until 2010. Research on epitaxial growth for thin film crystalline silicon solar cells has gained

225

Vapour-Phase Graphene Epitaxy at Low Temperatures Lianchang Zhang1,2  

E-Print Network [OSTI]

Nano Res 1 Vapour-Phase Graphene Epitaxy at Low Temperatures Lianchang Zhang1,2 , Zhiwen Shi1 2012 ABSTRACT We report an epitaxial growth of graphene, including homo- and hetero-epitaxy on graphite yield large-area high- quality graphene with the desired number of layers over the entire substrate

Zhang, Guangyu

226

Substrate-Induced Band-Gap Opening in Epitaxial Graphene  

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

227

Substrate-Induced Band-Gap Opening in Epitaxial Graphene  

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

228

Fabrication of ?-Ga2O3 thin films and solar-blind photodetectors by laser MBE technology  

Science Journals Connector (OSTI)

Laser molecular beam epitaxy technology has been employed to deposit ?-gallium oxide (?-Ga2O3) on (0001) sapphire substrates. After optimizing the...

Guo, Daoyou; Wu, Zhenping; Li, Peigang; An, Yuehua; Liu, Han; Guo, Xuncai; Yan, Hui; Wang, Guofeng; Sun, Changlong; Li, Linghong; Tang, Weihua

2014-01-01T23:59:59.000Z

229

Self-corrected Sensors Based On Atomic Absorption Spectroscopy...  

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

corrected Sensors Based On Atomic Absorption Spectroscopy For Atom Flux Measurements In Molecular Beam Epitaxy. Self-corrected Sensors Based On Atomic Absorption Spectroscopy For...

230

Epitaxial silicide formation on recoil-implanted substrates  

SciTech Connect (OSTI)

An epitaxy-on-recoil-implanted-substrate (ERIS) technique is presented. A disordered surface layer, generated by forward recoil implantation of {approx}0.7-3x10{sup 15} cm{sup -2} of oxygen during Ar plasma etching of surface oxide, is shown to facilitate the subsequent epitaxial growth of {approx}25-35-nm-thick CoSi{sub 2} layers on Si(100). The dependence of the epitaxial fraction of the silicide on the recoil-implantation parameters is studied in detail. A reduction in the silicide reaction rate due to recoil-implanted oxygen is shown to be responsible for the observed epitaxial formation, similar to mechanisms previously observed for interlayer-mediated growth techniques. Oxygen is found to remain inside the fully reacted CoSi{sub 2} layer, likely in the form of oxide precipitates. The presence of these oxide precipitates, with only a minor effect on the sheet resistance of the silicide layer, has a surprisingly beneficial effect on the thermal stability of the silicide layers. The agglomeration of ERIS-grown silicide layers on polycrystalline Si is significantly suppressed, likely from a reduced diffusivity due to oxygen in the grain boundaries. The implications of the present technique for the processing of deep submicron devices are discussed.

Hashimoto, Shin; Egashira, Kyoko; Tanaka, Tomoya; Etoh, Ryuji; Hata, Yoshifumi; Tung, R. T. [Corporate Manufacturing and Development Division, Semiconductor Company, Matsushita Electric Industrial Co., Ltd., Kyoto 617-8520 (Japan); Department of Physics, Brooklyn College, City University of New York, Brooklyn, New York 11210 (United States)

2005-01-15T23:59:59.000Z

231

Cantilever Epitaxy Process Wins R&D 100 Award  

Broader source: Energy.gov [DOE]

Sandia National Laboratories received an R&D 100 Award from R&D Magazine for development of a new process for growing gallium nitride on an etched sapphire substrate. The process, called cantilever epitaxy, promises to make brighter and more efficient green, blue, and white LEDs.

232

BEAM LINE  

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

233

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

SciTech Connect (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

234

Strain controlled systematic variation of metal-insulator transition in epitaxial NdNiO{sub 3} thin films  

SciTech Connect (OSTI)

We report here the strain dependent structural and electrical transport properties of epitaxial NdNiO{sub 3} thin films. Pulsed laser deposition technique was used to grow the NdNiO{sub 3} thin films on c-axis oriented SrTiO{sub 3} single crystals. Deposited films were irradiated using 200 MeV Ag{sup 15+} ion beam at the varying fluence (1 Multiplication-Sign 10{sup 11}, 5 Multiplication-Sign 10{sup 11}, and 1 Multiplication-Sign 10{sup 12} ions/cm{sup 2}). X-ray diffraction studies confirm the epitaxial growth of the deposited films, which is maintained even up to the highest fluence. Rise in the in-plane compressive strain has been observed after the irradiation. All the films exhibit metal-insulator transition, however, a systematic decrease in the transition temperature (T{sub MI}) has been observed after irradiation, which may be attributed to the increase in the in-plane compression. Raman spectroscopy data reveal that this reduction in T{sub MI}, with the irradiation, is related to the decrease in band gap due to the stress generated by the in-plane compressive strain.

Kumar, Yogesh [Materials Science Division, Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Choudhary, R. J. [UGC-DAE Consortium for Scientific Research, Indore 452 001 (India); Kumar, Ravi [Materials Science Division, Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Centre for Material Science and Engineering, National Institute of Technology, Hamirpur 177 005 (India)

2012-10-01T23:59:59.000Z

235

Beam-Bem interactions  

SciTech Connect (OSTI)

In high energy storage-ring colliders, the nonlinear effect arising from beam-beam interactions is a major source that leads to the emittance growth, the reduction of beam life time, and limits the collider luminosity. In this paper, two models of beam-beam interactions are introduced, which are weak-strong and strong-strong beam-beam interactions. In addition, space-charge model is introduced.

Kim, Hyung Jin; /Fermilab

2011-12-01T23:59:59.000Z

236

E-Print Network 3.0 - atlas combined beam Sample Search Results  

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

Charged-particle multiplicities ... Source: Titov, Anatoly - Laboratory of Molecular Beams, Petersburg Nuclear Physics Institute Collection: Physics 2 ATLAS ATLAS ATLAS ATLAS...

237

Faceted ceramic fibers, tapes or ribbons and epitaxial devices therefrom  

DOE Patents [OSTI]

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

2013-07-09T23:59:59.000Z

238

Microwave studies of weak localization and antilocalization in epitaxial graphene  

SciTech Connect (OSTI)

A microwave detection method was applied to study weak localization and antilocalization in epitaxial graphene sheets grown on both polarities of SiC substrates. Both coherence and scattering length values were obtained. The scattering lengths were found to be smaller for graphene grown on C-face of SiC. The decoherence rate was found to depend linearly on temperature, showing the electron-electron scattering mechanism.

Drabi?ska, Aneta; Kami?ska, Maria [Faculty of Physics, University of Warsaw, ul. Ho?a 69, 00-681 Warsaw (Poland); Wo?o?, Agnieszka [Faculty of Physics, University of Warsaw, ul. Ho?a 69, 00-681 Warsaw, Poland and Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Strupinski, Wlodek [Institute of Electronic Materials Technology, ul. Wólczyñska 133, 01-919 Warsaw (Poland); Baranowski, J. M. [Faculty of Physics, University of Warsaw, ul. Ho?a 69, 00-681 Warsaw, Poland and Institute of Electronic Materials Technology, ul. Wólczyñska 133, 01-919 Warsaw (Poland)

2013-12-04T23:59:59.000Z

239

Faceted ceramic fibers, tapes or ribbons and epitaxial devices therefrom  

DOE Patents [OSTI]

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

240

Epitaxial HTS bolometers on silicon for IR detection  

SciTech Connect (OSTI)

Silicon wafers have shown promise for the fabrication of photothermal IR detectors (i.e., bolometers) from epitaxial HTS thin films of YBa{sub 2}Cu{sub 3}O{sub (7{minus}{delta})} (YBCO). Conventional IC-grade wafers, ultrathin wafers, and micromachined-silicon membrane windows in conventional wafers, are all suitable, but the latter provides considerable advantage for bolometer performance. The high thermal conductivity and strength of silicon make it ideal for submicron-thick window designs. Epitaxy in the HTS film is advantageous, since it reduces granular disorder, the primary cause of dark noise (resistance-fluctuations) in the detector. Mid-to-far-IR transparency of Si at 90 K is unique among those substrates that support high-quality epitaxial YBCO films. This Si transparency to IR can be used for various improvements in the optical design of these devices. The authors review the thermal and optical advantages of silicon substrates, device fabrication issues, and bolometer modeling. Thermal modeling of membrane bolometers indicates that the steady-state temperature-rise profile is nonuniform, but that this does not degrade the response linearity of the bolometer. Certain size limits and trade-offs in the design, will be important in the final device performance. They also discuss applications to FTIR instruments, and extensions of this technology to arrays including a novel on-chip transform spectrometer design.

Fenner, D.B.; Li, Q.; Hamblen, W.D.; Luo, J.; Hamblen, D.G. [AFR, Inc., East Hartford, CT (United States). Superconductivity Group; Budnick, J.I. [Univ. of Connecticut, Storrs, CT (United States). Dept. of Physics

1994-12-31T23:59:59.000Z

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

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

SciTech Connect (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

242

The influence of prestrained metalorganic vapor phase epitaxial gallium-nitride templates on hydride vapor phase epitaxial growth  

Science Journals Connector (OSTI)

We have varied the strain situation in metalorganic vapor phase epitaxial (MOVPE) grown gallium-nitride (GaN) by exchanging the nucleation layer and by inserting a submono-Si x N y -interlayer in the first few hundred nanometers of growth on sapphire substrates. The influence on the MOVPE template and subsequent hydride vapor phase epitaxial (HVPE) growth could be shown by in-situ measurements of the sample curvature. Using the results of these investigations we have established a procedure to confine the curvature development in MOVPE and HVPE growth to a minimum. By increasing the layer thickness in HVPE we could create self-separated freestanding GaN layers with small remaining curvature.

2014-01-01T23:59:59.000Z

243

X-ray Microdiffraction from ?-Ti0.04Fe1.96O3 (0001) Epitaxial...  

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

(0001) Epitaxial Film Grown Over ?-Cr2O3 Buffer Layer Boundary. X-ray Microdiffraction from ?-Ti0.04Fe1.96O3 (0001) Epitaxial Film Grown Over...

244

Wave mechanics of a two-wire atomic beam splitter  

SciTech Connect (OSTI)

We consider the problem of an atomic beam propagating quantum mechanically through an atom beam splitter. Casting the problem in an adiabatic representation (in the spirit of the Born-Oppenheimer approximation in molecular physics) sheds light on explicit effects due to nonadiabatic passage of the atoms through the splitter region. We are thus able to probe the fully three-dimensional structure of the beam splitter, gathering quantitative information about mode mixing, splitting ratios, and reflection and transmission probabilities.

Bortolotti, Daniele C.E.; Bohn, John L. [JILA and Department of Physics, University of Colorado, Boulder, Colorado 80309-0440 (United States)

2004-03-01T23:59:59.000Z

245

HNCO in molecular clouds  

SciTech Connect (OSTI)

In a survey of 18 molecular clouds, HNCO J/sub K/-1K1..-->..J'/sub K/'-1K'1 = 5/sub 05/..-->..4/sub 05/ and 4/sub 04/..-->..3/sub 03/ emission was etected in seven clouds, and possibly in one other. Emission in these transitions originates in high-density regions (n> or approx. =10/sup 6/ cm/sup -3/). The molecule's excitation requirements allow us to derive limits to excitation temperatures an optical depths. We discuss the possibility of clumping with respect to the beam and compare our results with data from other molecular species. The HNCO emission from Sgr A is an ordder of magnitude larger than the other detected sources as is the ratio ..delta..T +- /sub A/(HNCO 5/sub 05/..-->..4/sub 04/)/..delta..T +- /sub A/(C/sup 18/O 1..-->..0). HNCO is probably a constituent of most molecular clouds.

Jackson, J.M.; Armstrong, J.T.; Barrett, A.H.

1984-05-15T23:59:59.000Z

246

Small epitaxial graphene devices for magnetosensing applications V. Panchal, K. Cedergren, R. Yakimova, A. Tzalenchuk, S. Kubatkin et al.  

E-Print Network [OSTI]

Small epitaxial graphene devices for magnetosensing applications V. Panchal, K. Cedergren, R://jap.aip.org/about/rights_and_permissions #12;Small epitaxial graphene devices for magnetosensing applications V. Panchal,1,2 K. Cedergren,3 R from 0.5 to 20.0 lm have been fabricated out of a monolayer graphene epitaxially grown on Si

Sheldon, Nathan D.

247

Epitaxial growth of lead zirconium titanate thin films on Ag buffered Si substrates using rf sputtering  

E-Print Network [OSTI]

substrates such as SrTiO3, MgO, and LaAlO3 using different deposition methods sputtering, pubed laser with good dif- fusion barrier properties and epitaxy with Si need to be used. In this work, we investigated grown epitaxially on HF-etched Si 001 with cube-on-cube orientation relationship, though the lattice

Laughlin, David E.

248

InAlAs EPITAXIAL GROWTH FOR WIDE BAND GAP SOLAR CELLS Marina S. Leite  

E-Print Network [OSTI]

InAlAs EPITAXIAL GROWTH FOR WIDE BAND GAP SOLAR CELLS Marina S. Leite 1 , Robyn L. Woo 2 , William vapor phase epitaxy and wide band gap solar cell fabrication. X-ray diffraction and transmissionAlAs solar cells lattice-matched to InP were grown and electrically characterized under AM 1.5 global 1-sun

Atwater, Harry

249

Exploring the Potential for High-Quality Epitaxial CdTe Solar Cells , Ana Kanevce2  

E-Print Network [OSTI]

Exploring the Potential for High-Quality Epitaxial CdTe Solar Cells Tao Song1 , Ana Kanevce2 National Renewable Energy Laboratory, Golden, CO, 80401, USA Abstract -- Traditional polycrystalline CdTeV and ~ 20%. Epitaxial CdTe with high-quality, low defect-density, and high carrier density, could yield

Sites, James R.

250

Self-assembly of silicide quantum dot arrays on stepped silicon surfaces by reactive epitaxy  

E-Print Network [OSTI]

investigated on the epitaxy and self- organization of laterally nanostructured transition metal TM silicideSelf-assembly of silicide quantum dot arrays on stepped silicon surfaces by reactive epitaxy L to be a flexible and a convenient method for the preparation of dense arrays of Co silicide quantum dots

Ortega, Enrique

251

Thin crystalline silicon solar cells based on epitaxial films grown at 165C by RF PECVD  

E-Print Network [OSTI]

1 Thin crystalline silicon solar cells based on epitaxial films grown at 165°C by RF PECVD Romain temperatures. Keywords : Low temperature, epitaxy, PECVD, Si thin film, Solar cell #12;2 1. Introduction: martin.labrune@polytechnique.edu ABSTRACT We report on heterojunction solar cells whose thin intrinsic

252

Effect of functionalization on the electrostatic charging, tunneling, and Raman spectroscopy of epitaxial graphene  

E-Print Network [OSTI]

of epitaxial graphene Jeongmin Hong, Sandip Niyogi, Elena Bekyarova, Mikhail E. Itkis, Palanisamy Ramesh graphene Appl. Phys. Lett. 101, 111602 (2012); 10.1063/1.4752443 Evidences of electrochemical graphene (2012); 10.1063/1.4725489 Pinned and unpinned epitaxial graphene layers on SiC studied by Raman

253

Optimization of the tunability of barium strontium titanate films via epitaxial stresses  

E-Print Network [OSTI]

Optimization of the tunability of barium strontium titanate films via epitaxial stresses Z.-G. Ban The tunability of epitaxial barium strontium titanate films is analyzed theoretically using a phenomenological.1063/1.1524310 I. INTRODUCTION Thin films of barium strontium titanate (BaxSr1 xTiO3, BST have long been recognized

Alpay, S. Pamir

254

247IEEE ELECTRON DEVICE LETTERS, VOL. 13,NO. 5, MAY 1992 InP/InGaAs Heterojunction Bipolar  

E-Print Network [OSTI]

been achieved by gas-source molecular beam epitaxy (GSMBE) using carbon tetrachloride (CCI a role in carbon incorporation or acceptor activity. Chin et al. [6] used carbon tetrachloride (CC1 Transistors Grown by Gas-Source Molecular Beam Epitaxy with Carbon-Doped Base Russell C. Gee, Tsung-Pei Chin

Woodall, Jerry M.

255

LANSCE beam current limiter  

SciTech Connect (OSTI)

The Radiation Security System (RSS) at the Los Alamos Neutron Science Center (LANSCE) provides personnel protection from prompt radiation due to accelerated beam. Active instrumentation, such as the Beam Current Limiter, is a component of the RSS. The current limiter is designed to limit the average current in a beam line below a specific level, thus minimizing the maximum current available for a beam spill accident. The beam current limiter is a self-contained, electrically isolated toroidal beam transformer which continuously monitors beam current. It is designed as fail-safe instrumentation. The design philosophy, hardware design, operation, and limitations of the device are described.

Gallegos, F.R.

1996-06-01T23:59:59.000Z

256

Strong circular photogalvanic effect in ZnO epitaxial films  

SciTech Connect (OSTI)

A strong circular photogalvanic effect (CPGE) in ZnO epitaxial films was reported under interband excitation. It was observed that CPGE current is as large as 100 nA/W in ZnO, which is about one order in magnitude higher than that in InN film while the CPGE currents in GaN films are not detectable. The possible reasons for the above observations are the strong spin orbit coupling in ZnO or the inversed valence band structure of ZnO.

Zhang, Q.; Wang, X. Q.; Yin, C. M.; Shen, B. [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Chen, Y. H.; Chang, K. [Laboratory of Semiconductor Materials Science, Institute of Semiconductors, CAS, Beijing 100083 (China); Ge, W. K. [Department of Physics, Tsinghua University, Beijing 100871 (China)

2011-12-23T23:59:59.000Z

257

Electronic states in epitaxial graphene fabricated on silicon carbide  

SciTech Connect (OSTI)

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

258

Modification of epitaxial oxide films with ion implantation  

SciTech Connect (OSTI)

Ion implantation is used to modify the properties of oxide (YBCO and YSZ) thin films. Both superconducting and dielectric epitaxial oxide films, grown by laser ablation, are studied. The properties of the implanted oxide films are characterized by SIMS, XPS, DC resistivity and AC susceptibility measurements. By introducing reactive ions into superconducting oxide films, the conductivity of the material is inhibited possibly due to the interaction of the implanted ions with oxygen originally bound to the copper atoms. Al, Si, Ag and Ca ions are implanted into epitaxial YBCO films with injection energies ranging from 50--100 KeV and doses ranging from 1 {times} 10{sup 15}--1 {times} 10{sup 16}/cm{sup 2}. XPS analysis shows that the implanted Si ions form SiO{sub x}. The inhibition method has been applied to the fabrication of superconducting electronic devices, such as SQUIDs. Dielectric oxide films are doped by the implantation of conductive and nonconductive ions. YSZ films are doped with Ag and Si ions and the ions are found to increase the conductivity.

Hong, S.H.; Miller, J.R.; Ma, Q.Y.; Yang, E.S. [Columbia Univ., New York, NY (United States). Dept. of Electrical Engineering; Fenner, D.B. [AFR Inc., East Hartford, CT (United States); Yang, C.Y. [Santa Clara Univ., CA (United States). Microelectronics Lab.; Budnick, J.I. [Univ. of Connecticut, Storrs, CT (United States). Dept. of Physics

1996-11-01T23:59:59.000Z

259

BEAMS3D Neutral Beam Injection Model  

SciTech Connect (OSTI)

With the advent of applied 3D fi elds in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous velocity reduction, and pitch angle scattering are modeled with the ADAS atomic physics database [1]. Benchmark calculations are presented to validate the collisionless particle orbits, neutral beam injection model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields.

Lazerson, Samuel

2014-04-14T23:59:59.000Z

260

A TALE OF TWO BEAMS: GAUSSIAN BEAMS AND BESSEL BEAMS ROBERT L. NOWACK  

E-Print Network [OSTI]

A TALE OF TWO BEAMS: GAUSSIAN BEAMS AND BESSEL BEAMS ROBERT L. NOWACK Abstract. An overview is given of two types of focused beams, Gaussian beams and Bessel beams. First I describe some of the basic properties of Gaussian beams in homogeneous media which stay collimated over a certain distance range after

Nowack, Robert L.

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

LBNL-45363, CBP Note 333 BEAM-BEAM SIMULATIONS FOR SEPARATED BEAMS  

E-Print Network [OSTI]

LBNL-45363, CBP Note 333 BEAM-BEAM SIMULATIONS FOR SEPARATED BEAMS Miguel A. Furman, Center for Beam Physics, LBNL, Berkeley, CA 94720 Abstract We present beam-beam simulation results from a strong- strong gaussian code for separated beams for the LHC and RHIC. The frequency spectrum produced

Furman, Miguel

262

LBNL-46223, CBP Note 350 BEAM-BEAM SIMULATIONS FOR SEPARATED BEAMS IN THE LHC  

E-Print Network [OSTI]

LBNL-46223, CBP Note 350 BEAM-BEAM SIMULATIONS FOR SEPARATED BEAMS IN THE LHC M. A. Furman, W. C. Turner, Center for Beam Physics, LBNL, Berkeley, CA 94720, USA Abstract We present beam-beam simulation results from a strong- strong gaussian code for separated beams for the LHC. We focus on the possible

Furman, Miguel

263

BEAMS: Curiosity | Jefferson Lab  

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

BEAMS: Curiosity January 9, 2013 BEAMS, Becoming Excited About Math and Science, is one of our education programs. In particular, it is the only one in which I participate with...

264

Molecular Foundry  

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

265

Ion Beams - Radiation Effects Facility / Cyclotron Institute...  

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

Ion Beams Available Beams Beam Change Times Measurements Useful Graphs Various ion beams have been developed specifically for the Radiation Effects Facility. These beams...

266

ATA beam director experiment  

SciTech Connect (OSTI)

This report describes beam director elements for an experiment at the Advanced Test Accelerator. The elements described include a vernier magnet for beam aiming, an achromat magnet, and an isolation system for the beam interface. These components are built at small scale for concept testing. (JDH)

Lee, E.P.; Younger, F.C.; Cruz, G.E.; Nolting, E.

1986-06-23T23:59:59.000Z

267

Inexpensive dual beam turbidimeter  

Science Journals Connector (OSTI)

...Articles Articles Inexpensive dual beam turbidimeter Cathie Lubell Thomas Barry Edward Brody Gregory Hearn This dual beam turbidimeter...74D728B5-2B21-11D7-8648000102C1865D Inexpensive dual beam turbidimeter Lubell Cathie Author Barry Thomas Author Brody Edward Author Hearn...

Cathie Lubell; Thomas Barry; Edward Brody; Gregory Hearn

268

Dielectric tunability of ,,110... oriented barium strontium titanate epitaxial films on ,,100... orthorhombic substrates  

E-Print Network [OSTI]

Dielectric tunability of ,,110... oriented barium strontium titanate epitaxial films on ,,100 materials such as barium strontium titanate Ba1-xSrxTiO3 BST have emerged as leading candidates

Alpay, S. Pamir

269

Structure, magnetic properties and magnetoelastic anisotropy in epitaxial Sr(Ti???Co?)O? films  

E-Print Network [OSTI]

We report the structure, magnetic properties and magnetoelastic anisotropy of epitaxial Sr(Ti???Co?)O? films grown on LaAlO? (001) and SrTiO? (001) substrates by pulsed laser deposition. Room temperature ferromagnetism was ...

Bi, Lei

270

Applied Materials Develops an Advanced Epitaxial Growth System to Bring Down LED Costs  

Broader source: Energy.gov [DOE]

With the help of DOE funding, Applied Materials has developed an advanced epitaxial growth system for gallium nitride (GaN) LED devices that decreases operating costs, increases internal quantum efficiency, and improves binning yields.

271

E-Print Network 3.0 - atomic layer epitaxy Sample Search Results  

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

the surface of the grown MnSi layer. On the atomic scale, scanning... Epitaxial growth of silicide layers on Si substrates has attracted much attention due to their...

272

Enhanced Magnetism in Epitaxial SrRuO3 Thin Films  

E-Print Network [OSTI]

Enhanced Magnetism in Epitaxial SrRuO 3 A. J. Grutter, 1, 2and their e?ects on magnetism. In this paper we demonstrateXMCD con?rmed that the magnetism originates from the Ru 4+

Grutter, A.J.

2010-01-01T23:59:59.000Z

273

Epitaxial Growth and Microstructure of Cu2O Nanoparticle/thin...  

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

Microstructure of Cu2O Nanoparticlethin Films on SrTiO3(100). Epitaxial Growth and Microstructure of Cu2O Nanoparticlethin Films on SrTiO3(100). Abstract: Cuprous oxide (Cu2O)...

274

Electrocaloric properties of epitaxial strontium titanate films I. B. Misirlioglu,2  

E-Print Network [OSTI]

Electrocaloric properties of epitaxial strontium titanate films J. Zhang,1 I. B. Misirlioglu,2 S. P; published online 1 June 2012) The electrocaloric (EC) response of strontium titanate thin films is computed

Alpay, S. Pamir

275

White Light Generating Nonradiative Energy Transfer Directly from Epitaxial Quantum Wells to Colloidal Nanocrystal Quantum Dots  

Science Journals Connector (OSTI)

We present white light generating nonradiative Förster resonance energy transfer at a rate of (2ns)-1directly from epitaxial InGaN/GaN quantum wells to CdSe/ZnS...

Nizamoglu, Sedat; Sari, Emre; Baek, Jong-Hyeob; Lee, In-Hwan; Demir, Hilmi Volkan

276

Neutral beam monitoring  

DOE Patents [OSTI]

Method and apparatus for monitoring characteristics of a high energy neutral beam. A neutral beam is generated by passing accelerated ions through a walled cell containing a low energy neutral gas, such that charge exchange neutralizes the high energy ion beam. The neutral beam is monitored by detecting the current flowing through the cell wall produced by low energy ions which drift to the wall after the charge exchange. By segmenting the wall into radial and longitudinal segments various beam conditions are further identified.

Fink, Joel H. (Livermore, CA)

1981-08-18T23:59:59.000Z

277

Introduction of Artificial Pinning Center into PLD-YBCO Coated Conductor on IBAD and Self-Epitaxial CeO2 Buffered Metal Substrate  

SciTech Connect (OSTI)

In order to fabricate YBa2Cu3O7-x (YBCO) coated conductors with high critical current density Jc in magnetic fields, we fabricated YBCO coated conductors with artificial pinning centers by the pulsed laser deposition (PLD) method on a self epitaxial PLD-CeO2 layer and ion-beam assisted deposition (IBAD)-Gd2Zr2O7 (GZO) buffered Hastelloy tape. Artificial pinning centers were introduced by the PLD deposition using the yttria-stabilized zirconia (YSZ) oxide target (nano-dot method) and YBCO target including YSZ particles (mixed target method). In the experiments using YSZ oxide target, YSZ nano-dots were observed. They were approximately 15 nm in height and 10 nm to 70 nm in diameter. We found that the density of nano-dots was controlled by the number of laser pulses. These samples exhibited higher Jc than YBCO films in magnetic fields. Furthermore, a similar improvement of Jc was observed in the experiments using YBCO target including YSZ particles. TEM observation revealed that columnar nano-structure made of BaZrO3 was formed during YBCO deposition and it was effective for pinning. We call this new epitaxial nano-structure 'bamboo structure' from its anisotropic growth and morphology.

Kobayashi, H.; Yamada, Y.; Ishida, S.; Takahashi, K.; Konishi, M.; Ibi, A.; Miyata, S. [Superconductivity Research Laboratory, ISTEC, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, 456-8587 (Japan); Kato, T.; Hirayama, T. [Materials R and D Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan); Shiohara, Y. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062 (Japan)

2006-03-31T23:59:59.000Z

278

Site-controlled fabrication of Ga nanodroplets by focused ion beam  

SciTech Connect (OSTI)

Ga droplets are created by focused ion beam irradiation of GaAs surface. We report that ordered Ga droplets can be formed on the GaAs surface without any implantation damage. The droplets are characterized with bigger sizes than those droplets formed on damaged area. These aligned Ga droplets are formed via the migration of Ga atoms from ion irradiation area to the edge of undamaged GaAs surface and further nucleation into droplets. The morphological evolution and size distribution of these nanodroplets are investigated systematically with different beam irradiation time and incident angles. Based on this method, well positioned Ga nanodroplets, such as chains, are achieved by using focus ion beam patterning. The controllable assembly of droplets on undamaged semiconductor surface can be used to fabricate templates, to fabricate quantum structures and quantum devices by droplet epitaxy technique.

Xu, Xingliang; Wang, Zhiming M., E-mail: zhmwang@gmail.com [State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083 (China); Wu, Jiang; Li, Handong; Zhou, Zhihua [State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Wang, Xiaodong [Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083 (China)

2014-03-31T23:59:59.000Z

279

Growth of epitaxial PrO sub 2 thin films on hydrogen terminated Si (111) by pulsed laser deposition  

SciTech Connect (OSTI)

A new epitaxial oxide, PrO{sub 2}, has been grown on Si (111) by pulsed laser deposition. X-ray diffraction shows that films are oriented with the PrO{sub 2}(111) direction parallel to the substrate (111). The full width at half maximum for the omega rocking curve on the PrO{sub 2} (222) peak is as low as 0.75{degree}, while phi scans indicate {ital in}-{ital plane} epitaxial alignment to better than one degree. In the best quality films, epitaxy is almost pure type-{ital b} epitaxy which is characteristic of epitaxial CaF{sub 2} on Si. To achieve epitaxy, it is essential to remove the native silicon oxide from the substrate prior to film growth. This is done at room temperature using a wet-chemical hydrogen-termination procedure.

Fork, D.K. (Xerox Palo Alto Research Center, Palo Alto, CA (USA) Department of Applied Physics, Stanford University, Stanford, CA (USA)); Fenner, D.B. (Xerox Palo Alto Research Center, Palo Alto, CA (USA) Santa Clara University, Physics Department, Santa Clara, CA (USA)); Geballe, T.H. (Department of Applied Physics, Stanford University, Stanford, CA (USA))

1990-10-15T23:59:59.000Z

280

Beam-Gas  

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

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

Ion Beam Materials Lab  

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

282

Noninterceptive beam diagnostics  

SciTech Connect (OSTI)

The need for accurate real-time diagnostics is critical for high-power particle beams. This paper describes the present level of development of noninterceptive devices for these beams. Discussion will be related to diagnostic measurements as they occur along the beamline, from ion-source performance through presentation to an RFQ and measures of the RFQ output, using the cw beam at Los Alamos as a guide. 23 refs.

Chamberlin, D.D.

1985-01-01T23:59:59.000Z

283

Kicked surface muon beams  

Science Journals Connector (OSTI)

The possibility of splitting a surface muon beam into three separate components using an ... and could be very effectively used to provide muons to time differential ?SR experiments.

J. L. Beveridge

1992-01-01T23:59:59.000Z

284

Small beam nonparaxiality arrests selffocusing of optical beams Gadi Fibich  

E-Print Network [OSTI]

Small beam nonparaxiality arrests self­focusing of optical beams Gadi Fibich Department­focusing in the presence of small beam nonparaxiality is derived. Analysis of this equation shows that nonparaxiality remains small as the beam propa­ gates. Nevertheless, nonparaxiality arrests self­focusing when the beam

Soatto, Stefano

285

Epitaxial growth in dislocation-free strained asymmetric alloy films  

Science Journals Connector (OSTI)

Epitaxial growth in strained asymmetric, dislocation-free, coherent, alloy films is explored. Linear-stability analysis is used to theoretically analyze the coupled instability arising jointly from the substrate-film lattice mismatch (morphological instability) and the spinodal decomposition mechanism. Both the static and growing films are considered. Role of various parameters in determining stability regions for a coherent growing alloy film is investigated. In addition to the usual parameters: lattice mismatch ?, solute-expansion coefficient ?, growth velocity V, and growth temperature T, we consider the alloy asymmetry arising from its mean composition. The dependence of elastic moduli on composition fluctuations and the coupling between top surface and underlying bulk of the film also play important roles. The theory is applied to group III-V films such as GaAsN, InGaN, and InGaP and to group IV Si-Ge films at temperatures below the bare critical temperature Tc for strain-free spinodal decomposition. The dependences of various material parameters on mean concentration and temperature lead to significant qualitative changes.

Rashmi C. Desai; HoKwon Kim; Apratim Chatterji; Darryl Ngai; Si Chen; Nan Yang

2010-06-01T23:59:59.000Z

286

Structure and epitaxy studies of cobalt silicide/silicon heterostructures  

SciTech Connect (OSTI)

When considering transition metal silicides for use in integrated circuit technology, CoSi{sub 2} stands out as a silicide possessing an excellent combination of properties. However, the detrimental effects of CoSi{sub 2} pinhole formation seriously restricts the applicability of this silicide system. This study examines the structure/processing/property relationship of thin film cobalt silicide/silicon heterostructures grown on Si(111). The two primary objectives were: (1) identify the basic mechanisms associated with pinhole formation and cobalt silicide thin film growth; and (2) characterization of cobalt silicides grown by Si{sub a}/Co/Si{sub c} multilayer deposition and reaction and the effect this deposition technique has on the microstructure of cobalt silicide thin films. Interfacial pinhole formation was identified at the CoSi/Si interface and involves several active mechanisms. Epitaxial pinhole free CoSi{sub 2} films were grown by single-step annealing Si{sub a}/Co/Si{sub c} multilayer structures. Two step annealing Si{sub a}/Co/Si{sub c} multilayer thin films results in polycrystalline CoSi{sub 2}.

Zaluzec, M.J.

1991-01-01T23:59:59.000Z

287

Maskless lateral epitaxial overgrowth of GaN on sapphire  

SciTech Connect (OSTI)

The authors demonstrate a technique of lateral epitaxial overgrowth (LEO) of GaN, termed maskless LEO, in which no mask is deposited prior to LEO regrowth. Instead, a bulk (> 2 {micro}m) GaN layer on sapphire is selectively dry etched, leaving {approximately} 5 {micro}m-wide stripe mesas oriented in the <10{bar 1}0>{sub GaN} direction, with a 20 {micro}m period. These stripes serve as seeds for LEO GaN growth, which proceeds from the tops of the stripes and expands laterally, resulting in a T, or overhang, morphology. As for LEO over an SiO{sub 2} mask, significant defect reduction (from {approximately} 10{sup 9} cm{sup {minus}2} to {approximately} 10{sup 6} cm{sup {minus}2}) is observed in cross-sectional transmission electron microscopy (TEM). Atomic force microscopy of the top surface of the LEO GaN reveals that no threading dislocations with screw component terminate at the surfaces of laterally overgrown regions. X-ray diffraction measurements reveal that the wings exhibit a crystallographic tilt away from the seed regions in an azimuth perpendicular to the stripe direction; the tilt angle ({approximately} 0.4--0.5{degree}) is relatively independent of growth temperature and wing aspect ratio.

Fini, P.; Marchand, H.; Ibbetson, J.P.; Moran, B.; Zhao, L.; Denbaars, S.P.; Speck, J.S.; Mishra, U.K.

1999-07-01T23:59:59.000Z

288

New frontier in thin film epitaxy and nanostructured materials  

Science Journals Connector (OSTI)

Nanomaterials hold the key to the success of nanotechnology. This review starts with a new paradigm for thin film growth based upon matching of integral multiples of lattice planes across the film-substrate interface. This paradigm of domain matching epitaxy (DME) unifies small as well as large misfit systems utilising the concept of systematic domain variation. By controlling the kinetics of clustering and energetics of interfaces, it is possible to obtain nanoclusters of uniform size and create novel nanostructured materials by design, where relative orientation with respect to matrix can be controlled by DME. In nanostructured materials with unit dimensions 1â??100 nm, science and processing challenges include self-assembly processing, control of interfacial atoms and energetics, quantum confinement issues, nanoscale structure-property correlations. In addition, metastability of interfaces should be controlled for reliability in manufacturing of nanosystems. This paper presents fundamentals of synthesis and processing of nanomaterials, role of interfaces, nanoscale characterisation to establish atomic structure-property correlations and modelling to create novel nanostructured structural, magnetic, photonic and electronic systems with unique and improved properties for next-generation systems with new functionality.

Jagdish Narayan

2009-01-01T23:59:59.000Z

289

Low temperature epitaxial growth of Ge on cube- textured Ni  

SciTech Connect (OSTI)

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

290

Molecular biochemistry  

Science Journals Connector (OSTI)

... THIS text forms a very readable handbook which outlines the ... which outlines the fundamentals of electrostatic and dielectric theory on the one hand and of chemical bonding and molecular ...

B. Jennings

1978-09-07T23:59:59.000Z

291

Beam director design report  

SciTech Connect (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

292

Growth and characterisation of epitaxially ordered zinc aluminate domains on c-sapphire  

Science Journals Connector (OSTI)

Epitaxially ordered zinc aluminate domains with sub-micron dimensions are formed on bare c-sapphire substrates using a vapour phase method (with vapour generated by carbothermal reduction of ZnO) at various temperatures and growth durations. A zinc aluminate (ZnAl2O4) layer is formed by reaction of the source materials (Zn and O) with the substrate. We observe crystallites with a well-defined epitaxial relationship on the sapphire substrate in addition to polycrystalline material. The epitaxially oriented deposit displays the form of characteristically twinned (singly or multiply) grains of sub-micron dimensions with three variants, consistent with the c-sapphire substrate symmetry. Scanning electron microscopy and transmission electron microscopy studies show that the formation of these grains is associated with the presence of extended defects in the sapphire substrate. Epitaxially ordered grains formed at higher temperatures show a change in the nature of the twin boundaries and epitaxial relations as a function of growth time, attributed to the effects of annealing during growth.

J. Grabowska; R.T. Rajendra Kumar; E. McGlynn; K.K. Nanda; S.B. Newcomb; P.J. McNally; L. O'Reilly; J.-P. Mosnier; M.O. Henry

2008-01-01T23:59:59.000Z

293

Measurements - Ion Beams - Radiation Effects Facility / Cyclotron...  

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

Ion Beams Available Beams Beam Change Times Measurements Useful Graphs Measurements The beam uniformity and flux are determined using an array of five detectors. Each...

294

Neutrino Factories and Beta Beams  

E-Print Network [OSTI]

a Neutrino Factory Based on Muon Beams,” Proc. 2001 ParticleMD. [19] C. Rubbia et al. , “Beam Cooling with Ionisationthe required unstable ion beams has recently been suggested

Zisman, Michael S.

2006-01-01T23:59:59.000Z

295

Electro-oxidized Epitaxial Graphene Channel Field-Effect Transistors with Single-Walled Carbon Nanotube Thin Film  

E-Print Network [OSTI]

Electro-oxidized Epitaxial Graphene Channel Field-Effect Transistors with Single-Walled Carbon on the electronic properties of epitaxial graphene (EG) grown on silicon carbide substrates; we demonstrate the introduction of the reaction medium into the graphene galleries during electro-oxidation. The device

296

Epitaxial growth of nickel on Si(100) by dc magnetron sputtering  

SciTech Connect (OSTI)

The influence of the substrate temperature on the growth of highly textured Ni(111) and epitaxial Ni(200) with the relationships Ni[100] parallel Si[110] and Ni(001) parallel Si(001) on hydrogen terminated Si(100) wafer substrates by means of direct current magnetron sputtering is reported. In order to minimize crystal defect formation and to achieve a high quality epitaxial growth of Ni on Si, a two step deposition process was developed whereby different deposition conditions were used for an initial nickel seed layer and the remaining nickel film. The in-plane and out-of-plane structural properties of the films were investigated using x-ray scattering techniques, whereas magneto-optical Kerr effect and neutron reflectometry were used to confirm the magnetic nature of the epitaxially deposited nickel films.

Kreuzpaintner, W.; Stoermer, M.; Lott, D.; Solina, D.; Schreyer, A. [GKSS Forschungszentrum GmbH, Max-Planck-Strasse 1, 21502 Geesthacht (Germany)

2008-12-01T23:59:59.000Z

297

Intense proton beam source for ITER neutral-beam spectroscopy diagnostics  

SciTech Connect (OSTI)

An intense proton beam has been developed to evaluate a gas-cell neutralizer for use in an intense-neutral beam source for Tokomak Spectroscopy diagnostics. The allowed energy range of the proton stream is determined to be 50 to 70 keV from neutralization and reionization cross-sections and from the alpha particle charge exchange recombination intensity as a function of energy (baseline diagnostic). The neutralization evaluation source uses a flashover anode, magnetized, ion-diode. Neutral probes sensitive to energetic atomic and molecular hydrogen, developed to evaluate neutralizer performance, show neutral fluence from the ion-diode during the beam pulse. An array of Rogowski current probes, used to study the evolution of the current path, suggests that expansion of the anode plasma along the radial insulating magnetic field leads to impedance collapse.

Bartsch, R.R.; Davis, H.A.; Henins, I. [Los Alamos National Lab., NM (United States); Greenly, J.B. [Cornell Univ., Ithaca, NY (United States)

1994-09-01T23:59:59.000Z

298

Challenges in Accelerator Beam Instrumentation  

SciTech Connect (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

299

Beta-beams  

E-Print Network [OSTI]

Beta-beams is a new concept for the production of intense and pure neutrino beams. It is at the basis of a proposed neutrino facility, whose main goal is to explore the possible existence of CP violation in the lepton sector. Here we briefly review the original scenario and the low energy beta-beam. This option would offer a unique opportunity to perform neutrino interaction studies of interest for particle physics, astrophysics and nuclear physics. Other proposed scenarios for the search of CP violation are mentioned.

C. Volpe

2008-02-22T23:59:59.000Z

300

Molecular Foundry  

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

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

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

Effect of substrate temperature on the magnetic properties of epitaxial sputter-grown Co/Pt  

SciTech Connect (OSTI)

Epitaxial Co/Pt films have been deposited by dc-magnetron sputtering onto heated C-plane sapphire substrates. X-ray diffraction, the residual resistivity, and transmission electron microscopy indicate that the Co/Pt films are highly ordered on the atomic scale. The coercive field and the perpendicular magnetic anisotropy increase as the substrate temperature is increased from 100–250?°C during deposition of the Co/Pt. Measurement of the domain wall creep velocity as a function of applied magnetic field yields the domain wall pinning energy, which scales with the coercive field. Evidence for an enhanced creep velocity in highly ordered epitaxial Co/Pt is found.

Mihai, A. P.; Whiteside, A. L.; Canwell, E. J.; Marrows, C. H.; Moore, T. A., E-mail: t.a.moore@leeds.ac.uk [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Benitez, M. J.; McGrouther, D.; McVitie, S.; McFadzean, S. [School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)] [School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

2013-12-23T23:59:59.000Z

302

Surface photovoltage method for the quality control of silicon epitaxial layers on sapphire  

SciTech Connect (OSTI)

The surface photovoltage method is used to study “silicon-on-sapphire” epitaxial layers with a thickness of 0.3–0.6 ?m, which are used to fabricate p-channel MOS (metal—oxide-semiconductor) transistors with improved radiation hardness. It is shown that the manner in which the photoconductivity of the epitaxial layer decays after the end of a light pulse generated by a light-emitting diode (wavelength ?400 nm) strongly depends on the density of structural defects in the bulk of the structure. This enables control over how a “silicon-on-sapphire” structure is formed to provide the manufacturing of MOS structures with optimal operating characteristics.

Yaremchuk, A. F.; Starkov, A. V.; Zaikin, A. V., E-mail: lynch0000@gmail.com [National Rsearch University MIET (Russian Federation); Alekseev, A. V. [ZAO “Telekom-STV” (Russian Federation); Sokolov, E. M. [ZAO “Epiel” (Russian Federation)

2014-12-15T23:59:59.000Z

303

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

304

Courses on Beam Physics  

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

305

Focused ion beam system  

DOE Patents [OSTI]

A focused ion beam (FIB) system produces a final beam spot size down to 0.1 {mu}m or less and an ion beam output current on the order of microamps. The FIB system increases ion source brightness by properly configuring the first (plasma) and second (extraction) electrodes. The first electrode is configured to have a high aperture diameter to electrode thickness aspect ratio. Additional accelerator and focusing electrodes are used to produce the final beam. As few as five electrodes can be used, providing a very compact FIB system with a length down to only 20 mm. Multibeamlet arrangements with a single ion source can be produced to increase throughput. The FIB system can be used for nanolithography and doping applications for fabrication of semiconductor devices with minimum feature sizes of 0.1 m or less. 13 figs.

Leung, K.; Gough, R.A.; Ji, Q.; Lee, Y.Y.

1999-08-31T23:59:59.000Z

306

BNL | ATF Beam Diagnostics  

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

Beamline Spectrometry Both ATF beam lines have dipoles, which serve as spectrometers, the vacuum chambers on of these dipoles also have zero degree ports that may be covered with a...

307

Electron Beam Ion Sources  

E-Print Network [OSTI]

Electron beam ion sources (EBISs) are ion sources that work based on the principle of electron impact ionization, allowing the production of very highly charged ions. The ions produced can be extracted as a DC ion beam as well as ion pulses of different time structures. In comparison to most of the other known ion sources, EBISs feature ion beams with very good beam emittances and a low energy spread. Furthermore, EBISs are excellent sources of photons (X-rays, ultraviolet, extreme ultraviolet, visible light) from highly charged ions. This chapter gives an overview of EBIS physics, the principle of operation, and the known technical solutions. Using examples, the performance of EBISs as well as their applications in various fields of basic research, technology and medicine are discussed.

Zschornacka, G; Thorn, A

2013-01-01T23:59:59.000Z

308

BNL | ATF Beam Schedule  

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

309

The influence of bond flexibility and molecular size on the chemically selective bonding of In 2 O and Ga 2 O on GaAs (001)-c(2×8)/(2×4)  

Science Journals Connector (OSTI)

The surface structures formed upon deposition of In 2 O and Ga 2 O by molecular beam epitaxy onto the arsenic-rich GaAs (001)-c(2×8)/(2×4) surface have been studied using scanning tunneling microscopy and density functional theory. In 2 O initially bonds with indium atoms bonding to second layer gallium atoms within the trough and proceeds to insert into or between first layer arsenic dimer pairs. In contrast Ga 2 O only inserts into or between arsenic dimer pairs due to chemical site constraints. The calculated energy needed to bend a Ga 2 O molecule approximately 70° so that it can fit into an arsenic dimer pair is 0.6 eV less than that required for In 2 O . The greater flexibility of the Ga 2 O molecule causes its insertion site to be 0.77 eV more exothermic than the In 2 O insertion site. This result shows that although trends in the periodic table can be used to predict some surface reactions small changes in atomic size can play a significant role in the chemistry of gas/surface reactions through the indirect effects of bond angle flexibility and bond length stiffness.

M. J. Hale; J. Z. Sexton; D. L. Winn; A. C. Kummel; M. Erbudak; M. Passlack

2004-01-01T23:59:59.000Z

310

Small Spot, Brighter Beam  

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

311

Ion-beam superpinch  

Science Journals Connector (OSTI)

Intense nonrelativistic light-ion beams generated in magnetically insulated diodes can reach total beam currents large enough to confine charged fusion products within pinch channels which are formed by these beams if they are projected onto thermonuclear material. Furthermore, since the required beam currents are still below the critical Alfvén current, these pinch channels are magnetohydrodynamically stable. However, because the time these beams last is very short and of the order of 10 nsec, the thermonuclear target must have a density at least as large as solid-state density to satisfy the Lawson criterion. This large target density makes it necessary that the beam be focused down to a radius less than ? 10-2 cm, to balance the plasma pressure against the magnetic pressure. To make this focusing possible a new kind of a low-emittance intense ion source is proposed. It consists of pointlike pulsed dense plasma positioned in the field-free space behind a meshlike anode. The focusing itself can be done in three steps, first by sufficiently good ion optics, second by wall focusing, and third by radiation cooling. This inertial-confinement fusion concept avoids the problems of reaching this goal through highdensity target compression by ablative implosion.

F. Winterberg

1981-10-01T23:59:59.000Z

312

Wire Scanner Beam Profile Measurements: LANSCE Facility Beam Development  

SciTech Connect (OSTI)

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

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

Wafer Bonding and Epitaxial Transfer of GaSb-based Epitaxy to GaAs for Monolithic Interconnection of Thermophotovoltaic Devices  

SciTech Connect (OSTI)

GaInAsSb/AlGaAsSb/InAsSb/GaSb epitaxial layers were bonded to semi-insulating GaAs handle wafers with SiO{sub x}/Ti/Au as the adhesion layer for monolithic interconnection of thermophotovoltaic (TPV) devices. Epitaxial transfer was completed by removal of the GaSb substrate, GaSb buffer, and InAsSb etch-stop layer by selective chemical etching. The SiO{sub x}/TiAu provides not only electrical isolation, but also high reflectivity and is used as an internal back-surface reflector. Characterization of wafer-bonded epitaxy by high-resolution x-ray diffraction and time-decay photoluminescence indicates minimal residual stress and enhancement in optical quality. 0.54-eV GaInAsSb cells were fabricated and monolithically interconnected in series. A 10-junction device exhibited linear voltage building with an open-circuit voltage of 1.8 V.

C.A. Wang; D.A. Shiau; P.G. Murphy; P.W. O'brien; R.K. Huang; M.K. Connors; A.C. Anderson; D. Donetsky; S. Anikeev; G. Belenky; D.M. Depoy; G. Nichols

2003-06-16T23:59:59.000Z

315

Molecular nanostructure and nanotechnology  

Science Journals Connector (OSTI)

...Molecular nanostructure and nanotechnology compiled and edited by Chunli...Molecular nanostructure and nanotechnology Chunli Bai 1 Chen Wang 2...Molecular nanostructure and nanotechnology . This Theme Issue exemplifies...

2013-01-01T23:59:59.000Z

316

Light beam frequency comb generator  

DOE Patents [OSTI]

A light beam frequency comb generator uses an acousto-optic modulator to generate a plurality of light beams with frequencies which are uniformly separated and possess common noise and drift characteristics. A well collimated monochromatic input light beam is passed through this modulator to produce a set of both frequency shifted and unshifted optical beams. An optical system directs one or more frequency shifted beams along a path which is parallel to the path of the input light beam such that the frequency shifted beams are made incident on the modulator proximate to but separated from the point of incidence of the input light beam. After the beam is thus returned to and passed through the modulator repeatedly, a plurality of mutually parallel beams are generated which are frequency-shifted different numbers of times and possess common noise and drift characteristics.

Priatko, Gordon J. (Cupertino, CA); Kaskey, Jeffrey A. (Livermore, CA)

1992-01-01T23:59:59.000Z

317

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

318

Half integer quantum Hall effect in high mobility single layer epitaxial graphene  

E-Print Network [OSTI]

Half integer quantum Hall effect in high mobility single layer epitaxial graphene Xiaosong Wu,1 of is demonstrated here on a single graphene layer grown on the C-face of 4H silicon carbide. The mobility is 20 000. This is comparable to the best exfoliated graphene flakes on SiO2 and an order of magnitude larger than Si

319

Epitaxial graphene prepared by chemical vapor deposition on single crystal thin iridium films on sapphire  

E-Print Network [OSTI]

Epitaxial graphene prepared by chemical vapor deposition on single crystal thin iridium films Cedex 9, France (Dated: 15 March 2011) Uniform single layer graphene was grown on single-crystal Ir. These graphene layers have a single crystallographic orientation and a very low density of defects, as shown

Boyer, Edmond

320

Epitaxy of Nanocrystalline Silicon Carbide on Si(111) at Room Temperature  

E-Print Network [OSTI]

Epitaxy of Nanocrystalline Silicon Carbide on Si(111) at Room Temperature Roberto Verucchi carbide (SiC) has unique chemical, physical, and mechanical properties. A factor strongly limiting Si or plastics that cannot withstand high temperatures. Silicon carbide (SiC) has unique properties that make

Alfè, Dario

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.


321

Transition from Epitaxial to Nonepitaxial Ordered Monolayers in Pyrolyzed 8CB Studied by STM  

E-Print Network [OSTI]

-ordered, epitaxial monolayers on graphite. We have found that adding two oxidation products (to mimic the effects of air oxidation or pyrolysis) changes the surface ordering of 8CB, causing it to form cell dimensions of one of the oxidation products, both pure oxidation products were found to form

Patrick, David L.

322

Improved One-dimensional Analysis of CMOS Photodiode Including Epitaxial-Substrate Junction  

E-Print Network [OSTI]

1 Improved One-dimensional Analysis of CMOS Photodiode Including Epitaxial-Substrate Junction J. S-dimensional analysis of CMOS photodiode has been derived in which the effect of the substrate, which forms a high-empirical expression exhibits a good agreement with the measured spectral response of n+ pepi photodiodes fabricated

Hornsey, Richard

323

Surface Science 415 (1998) 363375 Epitaxial growth of Cu onto Si(111) surfaces at low temperature  

E-Print Network [OSTI]

to 10 and 3 monolayers (ML), respectively. This change is attributed to the silicide formation on the Si(111)-(7�7) surface at 160 K is proposed. The changes in periodicity are due to the silicide rights reserved. Keywords: Copper; Epitaxy; Electron­solid diffraction; Metallic films; Metal

Hasegawa, Shuji

324

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

325

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

326

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

327

Comparative study of microstructural characteristics of electrospark and Nd:YAG laser epitaxially growing coatings  

Science Journals Connector (OSTI)

As low-heat input welding processes, electrospark deposition and pulsed Nd:YAG laser cladding can be commonly used to prepare epitaxially growing coatings. However, these two processes have quite different characteristics in the energy input, the amount of materials involved, and the temperature gradient, and hence might result in dissimilar microstructural characteristics. In this paper, a comparative study has been made between microstructural characteristics in epitaxial growth coatings prepared by electrospark deposition and pulsed Nd:YAG laser cladding. Some interesting results have been achieved. Firstly, epitaxial growth coatings can be commonly achieved by these two techniques. Secondly, microstructural morphologies of these two epitaxial growth coatings are obviously different, cellular columnar structure prevails in the electrospark coating while columnar dendritic structure occupies most of the laser coating thickness, more importantly, electrospark coating remains fully columnar in the whole layer whereas laser coating tends to change from columnar to equiaxed at the top of the layer. Thirdly, electrospark coating possesses finer and more homogeneous microstructure than laser coating.

Yu-jiang Xie; Mao-cai Wang; Da-wei Huang

2007-01-01T23:59:59.000Z

328

GaAs photovoltaics and optoelectronics using releasable multilayer epitaxial assemblies  

E-Print Network [OSTI]

LETTERS GaAs photovoltaics and optoelectronics using releasable multilayer epitaxial assemblies-frequency electronics3,4 and most forms of optoelectronics5,6 . However, growing large, high quality wafers implementation. More tractable, yet still difficult, problems appear in advanced electronics and optoelectronics

Rogers, John A.

329

Self-assembly of triangular quantum dots on (111)A substrates by droplet epitaxy  

SciTech Connect (OSTI)

We report the self-assembly of triangular GaAs quantum dots (QDs) on (111)A substrates using droplet epitaxy. Shape transition from hexagonal to triangular QDs is observed with increasing crystallizing temperature. The mechanism of the morphological change is discussed in terms of different growth rates of step edges on a (111)A substrate.

Jo, M.; Mano, T.; Abbarchi, M.; Kuroda, T. [Advanced Photonics Materials Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Sakoda, K. [Advanced Photonics Materials Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan and Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan)

2014-05-15T23:59:59.000Z

330

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

SciTech Connect (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

331

X-ray radiation effects in multilayer epitaxial graphene Jeremy Hicks1  

E-Print Network [OSTI]

1 X-ray radiation effects in multilayer epitaxial graphene Jeremy Hicks1 , Rajan Arora2 , Eleazar and after exposure to a total ionizing dose (TID) of 12 Mrad(SiO2) using a 10 keV X-ray source. While we are mostly unaffected by radiation exposure. Combined with X-ray photoelectron spectroscopy (XPS) data

332

Epitaxial Growth of Diamond Films on Si(111) at Room Temperature by Mass-Selected Low-Energy C+ Beams  

Science Journals Connector (OSTI)

...supported by Energy, Mines, and Resources Canada research agreements and by Nat-ural Sciences and Engineering Research Council of Canada operating grant A7709. 12 October...extensive investigations of this system with LEED (low-energy elec-tron diffraction...

J. L. ROBERTSON; S. C. MOSS; Y. LIFSHITZ; S. R. KASI; J. W. RABALAIS; G. D. LEMPERT; E. RAPOPORT

1989-02-24T23:59:59.000Z

333

SLC beam dynamics issues  

SciTech Connect (OSTI)

The Stanford Linear Collider (SLC){sup 1,2} accelerates single bunches of electrons and positrons to 47 GeV per beam and collides them with small beam sizes and at high currents. The beam emittances and intensities required for present operation have significantly extended traditional beam quality limits. The electron source produces over 10{sup 11} e{sup {minus}} in each of two bunches. The damping rings provide coupled invariant emittances of 1.8 {times} 10{sup {minus}5} r-m at 4.5 {times} 10{sup 10} particles. The 50 GeV linac has successfully accelerated over 3 {times} 10{sup 10} particles with design invariant emittances of 3 {times} 10{sup {minus}5} r-m. The collider arcs are now sufficiently decoupled and matched in betatron space, so that the final focus can be chromatically corrected, routinely producing spot sizes ({sigma}{sub x}, {sigma}{sub y}) of 2.5 {mu}m at the interaction point. Spot sizes below 2 {mu}m have been made during tests. Instrumentation and feedback systems are well advanced, providing continuous beam monitoring and considerable pulse-by-pulse control. The luminosity reliability is about 60%. Overviews of the recent accelerator physics achievements used to obtain these parameters and the present limiting phenomena are described for each accelerator subsystem.

Seeman, J.T.

1991-12-01T23:59:59.000Z

334

Molecular Foundry  

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

335

Beam Profile Monitor With Accurate Horizontal And Vertical Beam Profiles  

DOE Patents [OSTI]

A widely used scanner device that rotates a single helically shaped wire probe in and out of a particle beam at different beamline positions to give a pair of mutually perpendicular beam profiles is modified by the addition of a second wire probe. As a result, a pair of mutually perpendicular beam profiles is obtained at a first beamline position, and a second pair of mutually perpendicular beam profiles is obtained at a second beamline position. The simple modification not only provides more accurate beam profiles, but also provides a measurement of the beam divergence and quality in a single compact device.

Havener, Charles C [Knoxville, TN; Al-Rejoub, Riad [Oak Ridge, TN

2005-12-26T23:59:59.000Z

336

Beam-Based Alignment  

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

337

Molecular Science Computing | EMSL  

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

Scientific Capabilities Molecular Science Computing Overview Cell Isolation and Systems Analysis Deposition and Microfabrication Mass Spectrometry Microscopy Molecular Science...

338

Fundamental Vibration of Molecular Hydrogen  

Science Journals Connector (OSTI)

The fundamental ground tone vibration of H2, HD, and D2 is determined to an accuracy of 2×10-4??cm-1 from Doppler-free laser spectroscopy in the collisionless environment of a molecular beam. This rotationless vibrational splitting is derived from the combination difference between electronic excitation from the X1?g+, v=0, and v=1 levels to a common EF1?g+, v=0 level. Agreement within 1? between the experimental result and a full ab initio calculation provides a stringent test of quantum electrodynamics in a chemically bound system.

G. D. Dickenson; M. L. Niu; E. J. Salumbides; J. Komasa; K. S. E. Eikema; K. Pachucki; W. Ubachs

2013-05-08T23:59:59.000Z

339

Colliding neutrino beams  

E-Print Network [OSTI]

From several neutrino oscillation experiments, we understand now that neutrinos have mass. However, we really don't know what mechanism is responsible for producing this neutrino mass. Current or planned neutrino experiments utilize neutrino beams and long-baseline detectors to explore flavor mixing but do not address the question of the origin of neutrino mass. In order to answer that question, neutrino interactions need to be explored at much higher energies. This paper outlines a program to explore neutrinos and their interactions with various particles through a series of experiments involving colliding neutrino beams.

Reinhard Schwienhorst

2007-11-08T23:59:59.000Z

340

Non-Paraxial Accelerating Beams  

E-Print Network [OSTI]

We present the spatially accelerating solutions of the Maxwell equations. Such non-paraxial beams accelerate in a circular trajectory, thus generalizing the concept of Airy beams. For both TE and TM polarizations, the beams exhibit shape-preserving bending with sub-wavelength features, and the Poynting vector of the main lobe displays a turn of more than 90 degrees. We show that these accelerating beams are self-healing, analyze their properties, and compare to the paraxial Airy beams. Finally, we present the new family of periodic accelerating beams which can be constructed from our solutions.

Ido Kaminer; Rivka Bekenstein; Jonathan Nemirovsky; Mordechai Segev

2012-02-03T23:59:59.000Z

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.


341

Graduate Program Micro-and Nanostructures  

E-Print Network [OSTI]

research area. Technologies that require clean rooms, such as molecular beam epitaxy, lithography, etching but young city Paderborn in the center of Germany, it provides an excellent environment for studies

Hellebrand, Sybille

342

The Metal-Insulator Phase Transition of Magnetite Surfaces Studied by Low-energy Ion Scattering  

Science Journals Connector (OSTI)

Several MBE (molecular beam epitaxy) thin-film and single-crystalline surfaces of magnetite have been investigated by means of the low-energy ion scattering (LEIS) technique. Distinct anomalies in the temperature...

N.-T.H. Kim-Ngan; W. Soszka

2004-12-01T23:59:59.000Z

343

Growth of Cr-doped TiO Films in the Rutile and Anatase Structures...  

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

of Cr-doped TiO Films in the Rutile and Anatase Structures by Oxygen Plasma Assisted Molecular Beam Epitaxy . Growth of Cr-doped TiO Films in the Rutile and Anatase Structures by...

344

Conductivity of Oriented Samaria-Doped Ceria Thin Films Grown...  

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

Conductivity of Oriented Samaria-Doped Ceria Thin Films Grown by Oxygen-plasma-assisted Molecular Beam Epitaxy. Conductivity of Oriented Samaria-Doped Ceria Thin Films Grown by...

345

Effect of the nitrogen ion energy on the MBE growth of thin gallium nitride films  

Science Journals Connector (OSTI)

The influence of the energy of bombarding nitrogen ions on the growth of thin gallium nitride (GaN) films under molecular beam epitaxy (MBE) conditions has been simulated using the method of balance kinetic eq...

D. V. Kulikov; Yu. V. Trushin; V. S. Kharlamov

2010-03-01T23:59:59.000Z

346

Pulsed ion beam source  

DOE Patents [OSTI]

An improved pulsed ion beam source is disclosed having a new biasing circuit for the fast magnetic field. This circuit provides for an initial negative bias for the field created by the fast coils in the ion beam source which pre-ionize the gas in the source, ionize the gas and deliver the gas to the proper position in the accelerating gap between the anode and cathode assemblies in the ion beam source. The initial negative bias improves the interaction between the location of the nulls in the composite magnetic field in the ion beam source and the position of the gas for pre-ionization and ionization into the plasma as well as final positioning of the plasma in the accelerating gap. Improvements to the construction of the flux excluders in the anode assembly are also accomplished by fabricating them as layered structures with a high melting point, low conductivity material on the outsides with a high conductivity material in the center. 12 figs.

Greenly, J.B.

1997-08-12T23:59:59.000Z

347

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

348

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

349

Role of hydrogen desorption in the chemical-vapor deposition of Si(100) epitaxial films using disilane  

Science Journals Connector (OSTI)

A scanning tunneling microscopy and spectroscopy study of the role of hydrogen desorption in epitaxial film growth on the Si(100) surface is presented. Following disilane adsorption, epitaxial growth is shown to be driven by the rebonding of the disilane fragments induced by H2 desorption. This requires the decomposition of only the higher surface hydrides and occurs between 640 and 670 K. The epitaxial layer formed in this manner has a 2×1 monohydride structure. Continuous exposure to disilane at 690 K resulted in multilayer epitaxial growth, the surface of which remains largely H passivated. This latter growth is in part due to a direct reaction between disilane and the monohydride surface.

John J. Boland

1991-07-15T23:59:59.000Z

350

Spectral research on an AlGaAs epitaxial material for a terahertz quantum-cascade laser  

Science Journals Connector (OSTI)

The spectral properties of a series of AlGaAs epitaxial films were studied by using a Fourier transform infrared spectrometer with an 80-degree grazing incidence reflection unit. The AlAs-like transversal optical...

Zhi-Yong Tan; Jun-Cheng Cao

2012-04-01T23:59:59.000Z

351

Reactions of carbon atoms in pulsed molecular beams  

SciTech Connect (OSTI)

This research program consists of a broad scope of experiments designed to unravel the chemistry of atomic carbon in its two spin states, P and D, by using well-controlled initial conditions and state-resolved detection of products. Prerequisite to the proposed studies (and the reason why so little is known about carbon atom reactions), is the development of clean sources of carbon atoms. Therefore, in parallel with the studies of its chemistry and reaction dynamics, the authors continuously explore new, state-specific and efficient ways of producing atomic carbon. In the current program, C({sup 3}P) is produced via laser ablation of graphite, and three areas of study are being pursued: (i) exothermic reactions with small inorganic molecules (e.g., O{sub 2}, N{sub 2}O, NO{sub 2}) that can proceed via multiple pathways; (ii) the influence of vibrational and translational energy on endothermic reactions involving H-containing reactants that yield CH products (e.g., H{sub 2}O H{sub 2}CO); (iii) reactions of C({sup 3}P) with free radicals (e.g., HCO, CH{sub 3}O). In addition, the authors plan to develop a source of C({sup 1}D) atoms by exploiting the pyrolysis of diazotetrazole and its salts in the ablation source. Another important goal involves collaboration with theoreticians in order to obtain relevant potential energy surfaces, rationalize the experimental results and predict the roles of translational and vibrational energies.

Reisler, H. [Univ. of Southern California, Los Angeles (United States)

1993-12-01T23:59:59.000Z

352

Photodissociation of cyclic compounds in a molecular beam  

SciTech Connect (OSTI)

A discussion on the dynamics and kinematics of photofragmentation-translational spectroscopy is presented, and the results are applied to experimental studies of four cyclic compounds: hexahydro-1,3,5- trinitro-1,3,5-triazine (RDX), s-tetrazine (ST), cyclohexene, (CHN), and 1,4-cyclohexadiene (CHDN). In infrared multiphoton dissociation (IRMPD) of RDX, the dominant primary channel is concerted triple fission to produce three CH/sub 2/N/sub 2/O/sub 2/ fragments which subsequently undergo secondary dissociation. Concerted reactions predominate over simple bond rupture not only in the number of channels, but also in the amount of products. Following /sup 1/B/sub 3u/ reverse arrow /sup 1/A/sub g/ (S/sub 1/ reverse arrow S/sub 0/) or /sup 1/B/sub 2u/ reverse arrow /sup 1/A/sub g/ (248 nm) excitation, ST reverts to the highly vibrationally excited ground electronic state through internal conversion (IC), and then decomposes into 2HCN + N/sub 2/ via concerted triple dissociation. The asymptotic angles between the N/sub 2/ and HCN groups from the center-of-mass of ST are 117.2/degree/ and 114.4/degree/ for S/sub 1/ reverse arrow S/sub 0/ and 248 nm excitation respectively.

Zhao, Xinsheng

1988-11-01T23:59:59.000Z

353

MOLECULAR BEAM PHOTOIONIZATION AND GAS-SURFACE SCATTERING  

E-Print Network [OSTI]

K) Ion gauge, (H) Motor water cooling lines. chamber. (J)into a water cooled copper cylinder. The motor fits very TheCooling water cavity. shaft mounting pieces. (D) Motor. (F)

Ceyer, S.T.

2010-01-01T23:59:59.000Z

354

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

355

Fast molecular-dynamics simulation for ferroelectric thin-film capacitors using a first-principles effective Hamiltonian  

Science Journals Connector (OSTI)

A newly developed fast molecular dynamics method is applied to BaTiO3 ferroelectric thin-film capacitors with short-circuited electrodes or under applied voltage. The molecular dynamics simulations based on a first-principles effective Hamiltonian clarify that dead layers (or passive layers) between ferroelectrics and electrodes markedly affect the properties of capacitors, and predict that the system is unable to hop between a uniformly polarized ferroelectric structure and a striped ferroelectric domain structure at low temperatures. Simulations of hysteresis loops of thin-film capacitors are also performed, and their dependence on film thickness, epitaxial constraints, and electrodes are discussed.

Takeshi Nishimatsu; Umesh V. Waghmare; Yoshiyuki Kawazoe; David Vanderbilt

2008-09-04T23:59:59.000Z

356

Gaussian Beams Enrique J. Galvez  

E-Print Network [OSTI]

Gaussian Beams Enrique J. Galvez Department of Physics and Astronomy Colgate University Copyright 2009 #12;ii #12;Contents 1 Fundamental Gaussian Beams 1 1.1 Spherical Wavefront in the Paraxial region . . . . . . . . . . . . . . . 1 1.2 Formal Solution of the Wave Equation . . . . . . . . . . . . . . . . . 3 1.2.1 Beam Spot w

Galvez, Enrique J. "Kiko"

357

Molecular Foundry  

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

358

Epitaxial InGaAsP/InP photodiode for registration of InP scintillation S. Luryi a,n  

E-Print Network [OSTI]

Epitaxial InGaAsP/InP photodiode for registration of InP scintillation S. Luryi a,n , A. Kastalsky scintillator InP epitaxy InGaAsP photodiodes a b s t r a c t Operation of semiconductor scintillators requires implemented an efficient and fast quaternary InGaAsP pin photodiode, epitaxially grown on the surface of an In

Stanacevic, Milutin

359

Effect of buffer layer growth temperature on epitaxial GaN films deposited by magnetron sputtering  

SciTech Connect (OSTI)

Epitaxial GaN films were deposited by reactive sputtering of a GaAs target in 100 % nitrogen at 700 deg. C on ZnO buffer layers grown at different substrate temperatures over sapphire substrates. High resolution X-ray diffraction measurements and the corresponding analysis show that the growth temperature of buffer layers significantly affects the micro-structural parameters of GaN epilayer, such as lateral coherence length, tilt and twist, while the vertical coherence length remains unaffected. The optimum substrate temperature for buffer layer growth has been found to be 300 deg. C. High epitaxial quality GaN film grown on such a buffer layer exhibited micro strain of 1.8x10{sup -4} along with screw and edge type dislocation densities of 7.87x10{sup 9} and 1.16x10{sup 11}, respectively.

Mohanta, P.; Singh, D.; Kumar, R.; Ganguli, T.; Srinivasa, R. S.; Major, S. S. [Center For Research in Nano-Technology and Science (India); Semiconductor Laser Section, RRCAT, Indore-452013 (India); Department of Metallurgical Engineering and Materials Science (India); Department of Physics, Indian Institute of Technology Bombay, Mumbai - 400076 (India)

2012-06-05T23:59:59.000Z

360

LSST beam simulator  

Science Journals Connector (OSTI)

It is always important to test new imagers for a mosaic camera before device acceptance and constructing the mosaic. This is particularly true of the LSST CCDs due to the fast beam illumination: at long wavelengths there can be significant beam divergence (defocus) inside the silicon because of the long absorption length for photons near the band gap. Moreover, realistic sky scenes need to be projected onto the CCD focal plane Thus, we need to design and build an f/1.2 re-imaging system. The system must simulate the entire LSST1 operation, including a sky with galaxies and stars with approximately black-body spectra superimposed on a spatially diffuse night sky emission with its complex spectral features.

J A Tyson; J Sasian; C Claver; G Muller; K Gilmor; M Klint

2014-01-01T23:59:59.000Z

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

SSRL BEAM PORT SCHEDULE  

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

362

SSRL BEAM PORT SCHEDULE  

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

363

SSRL BEAM PORT SCHEDULE  

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

364

SSRL BEAM PORT SCHEDULE  

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

365

All Beams 2013.xls  

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

1598 29 1079 9 1070 3.8 3.8 20.1 78 Kr 77.920 40 3117 140 622 20 602 14.2 14.4 41.4 Proton 1.007 40 40 0.1 8148 1.2 8147 0.012 0.012 0.56 Available Beams 40 A MeV 25 A MeV 15 A MeV...

366

Axion beams at HERA?  

E-Print Network [OSTI]

If the recently observed anomaly in the PVLAS experiment is due to the axion, then the powerful beams of synchrotron photons, propagating through high magnetic field of the HERA beamline, become strong axion sources. This gives a unique opportunity of detection of the axion-photon interactions by installing a small detector in the HERA tunnel, and to corroborate the axion hypothesis within a few days of running.

K. Piotrzkowski

2007-01-09T23:59:59.000Z

367

Proton beam therapy facility  

SciTech Connect (OSTI)

It is proposed to build a regional outpatient medical clinic at the Fermi National Accelerator Laboratory (Fermilab), Batavia, Illinois, to exploit the unique therapeutic characteristics of high energy proton beams. The Fermilab location for a proton therapy facility (PTF) is being chosen for reasons ranging from lower total construction and operating costs and the availability of sophisticated technical support to a location with good access to patients from the Chicago area and from the entire nation. 9 refs., 4 figs., 26 tabs.

Not Available

1984-10-09T23:59:59.000Z

368

Nanowire-templated lateral epitaxial growth of non-polar group III nitrides  

DOE Patents [OSTI]

A method for growing high quality, nonpolar Group III nitrides using lateral growth from Group III nitride nanowires. The method of nanowire-templated lateral epitaxial growth (NTLEG) employs crystallographically aligned, substantially vertical Group III nitride nanowire arrays grown by metal-catalyzed metal-organic chemical vapor deposition (MOCVD) as templates for the lateral growth and coalescence of virtually crack-free Group III nitride films. This method requires no patterning or separate nitride growth step.

Wang, George T. (Albuquerque, NM); Li, Qiming (Albuquerque, NM); Creighton, J. Randall (Albuquerque, NM)

2010-03-02T23:59:59.000Z

369

Growth, structure and electrical properties of epitaxial thulium silicide thin films on silicon  

SciTech Connect (OSTI)

Thulium silicide thin films were grown on (100) and (111) Si by evaporation of Tm metal and Si layers and annealing in a vacuum. Electron microscopy and x-ray diffraction results showed that the TmSi{sub 2{minus}x} layers are of high crystalline quality grown epitaxially on Si. Electrical resistivity measurements showed that TmSi{sub 2{minus}x} layers are metallic exhibiting magnetic ordering below 3 K. {copyright} {ital 1997 American Institute of Physics.}

Travlos, A.; Salamouras, N.; Boukos, N. [Institute of Materials Science, National Centre for Scientific Research Demokritos, Athens, (Greece) 15310] [Institute of Materials Science, National Centre for Scientific Research Demokritos, Athens, (Greece) 15310

1997-02-01T23:59:59.000Z

370

Veeco Develops a Tool to Reduce Epitaxy Costs and Increase LED Brightness  

Broader source: Energy.gov [DOE]

With the help of DOE funding, Veeco is working on reducing epitaxy costs and increasing LED efficiency by developing a physical vapor deposition (PVD) tool for depositing aluminum nitride buffer layers on LED substrates. PVD, also known as "sputtering," is an alternative to metal-organic chemical vapor deposition (MOCVD). PVD is a purely physical process that involves plasma sputter bombardment rather than a chemical reaction at the surface to be coated, as in MOCVD.

371

Epitaxial \\{MCrAlY\\} coating on a Ni-base superalloy produced by electrospark deposition  

Science Journals Connector (OSTI)

Abstract A novel electrospark deposition technique has been successfully developed to deposit epitaxially \\{MCrAlY\\} coating onto a directionally solidified nickel base superalloy. The coating is featured by cellular directionally solidified microstructure with primary ? phase. Its formation mechanism may be attributed to the facts that the alloy solidifies primarily with ? phase and solidification conditions of the tiny thin melt close to the limit of constitutional undercooling under the electrospark treatment condition.

Yu-jiang Xie; Mao-cai Wang

2006-01-01T23:59:59.000Z

372

Thermodynamic study of c-axis-oriented epitaxial Pb(Zr,Ti)O3 thin films  

Science Journals Connector (OSTI)

Thermodynamic characteristics of single crystalline Pb(Zr0.52Ti0.48)O3 (PZT) were investigated using c-axis oriented PZT films. The PZT films were epitaxially grown on Pt/MgO substrate and dielectric and ferroelectric properties were measured as a function of one-dimensional stress. The stress dependence of dielectric and ferroelectric properties was examined on the basis of the Landau-Devonshire’s phenomenological theory and the free energy coefficients of single crystalline PZT films were obtained. The dielectric stiffness coefficients and electrostrictive coefficient of epitaxial PZT films were obtained to be ?1=-1.30×108 (m/F), ?11=3.07×108 (m5/C2F), ?111=-3.11×107 (m9/C2F), and Q12=-5.70×10-2 (m4/C2), which are different from the values derived from the analysis of polycrystalline PZT. The temperature dependence of dielectric constant of the PZT films showed clear Curie-Weiss law and the dielectric stiffness coefficient ?1 derived from this measurement was almost same value from the analysis of stress dependence of the dielectricity of the epitaxial PZT films.

Isaku Kanno; Yu Yokoyama; Hidetoshi Kotera; Kiyotaka Wasa

2004-02-12T23:59:59.000Z

373

The correlation of epitaxial graphene properties and morphology of SiC (0001)  

SciTech Connect (OSTI)

The electronic properties of epitaxial graphene (EG) on SiC (0001) depend sensitively on the surface morphology of SiC substrate. Here, 2–3 layers of graphene were grown on on-axis 6H-SiC with different step densities realized through controlling growth temperature and ambient pressure. We show that epitaxial graphene on SiC (0001) with low step density and straight step edge possesses fewer point defects laying mostly on step edges and higher carrier mobility. A relationship between step density and EG mobility is established. The linear scan of Raman spectra combined with the atomic force microscopy morphology images revealed that the Raman fingerprint peaks are nearly the same on terraces, but shift significantly while cross step edges, suggesting the graphene is not homogeneous in strain and carrier concentration over terraces and step edges of substrates. Thus, control morphology of epitaxial graphene on SiC (0001) is a simple and effective method to pursue optimal route for high quality graphene and will be helpful to prepare wafer sized graphene for device applications.

Guo, Y.; Guo, L. W., E-mail: lwguo@iphy.ac.cn, E-mail: xlchen@iphy.ac.cn; Huang, J.; Jia, Y. P.; Lin, J. J.; Lu, W.; Li, Z. L. [Research and Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Yang, R. [Nanoscale Physics and Devices Laboratory, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Chen, X. L., E-mail: lwguo@iphy.ac.cn, E-mail: xlchen@iphy.ac.cn [Research and Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100190 (China)

2014-01-28T23:59:59.000Z

374

Nanoscale molecularly imprinted polymers and method thereof  

DOE Patents [OSTI]

Nanoscale molecularly imprinted polymers (MIP) having polymer features wherein the size, shape and position are predetermined can be fabricated using an xy piezo stage mounted on an inverted microscope and a laser. Using an AMF controller, a solution containing polymer precursors and a photo initiator are positioned on the xy piezo and hit with a laser beam. The thickness of the polymeric features can be varied from a few nanometers to over a micron.

Hart, Bradley R. (Brentwood, CA); Talley, Chad E. (Brentwood, CA)

2008-06-10T23:59:59.000Z

375

Nondestructive Damage Detection in General Beams  

E-Print Network [OSTI]

is to provide NDE methodologies that simultaneously identify the location, the extent, and the severity of damage in general beams. By general beams, we mean beyond Euler-Bernoulli beams (i.e. slender beams) to deep beams and stubby beams whose response may...

Dincal, Selcuk

2010-12-08T23:59:59.000Z

376

Polarity determination for MOCVD growth of GaN on Si(111) by convergent beam electron diffraction[Metal Organic Chemical Vapor Deposition  

SciTech Connect (OSTI)

The polarity of laterally epitaxially overgrown (LEO) GaN on Si(111) with an AlN buffer layer grown by MOCVD has been studied by convergent beam electron diffraction (CBED). The LEO GaN was studied by cross-section and plan-view transmission electron microscopy (TEM). The threading dislocation density is less than 10{sup 8} cm{sup {minus}2} and no inversion domains were observed. CBED patterns were obtained at 200 kV for the <1 {bar 1} 00> zone. Simulation was done by many-beam solution with 33 zero-order beams. The comparison of experimental CBED patterns and simulated patterns indicates that the polarity of GaN on Si(111) is Ga face.

Zhao, L.; Marchand, H.; Fini, P.; Denbaars, S.P.; Mishra, U.K.; Speck, J.S.

2000-07-01T23:59:59.000Z

377

Beam-Beam Interaction Simulations with Guinea Pig  

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

378

Simulation of beam-beam effects in tevatron  

SciTech Connect (OSTI)

The Fermilab accelerator complex is in the middle of an upgrade plan Fermilab III. In the last phase of this upgrade the luminosity of the Tevatron will increase by at least one order of magnitude. In order to keep the number of interactions per crossing manageable for experiments, the number of bunches will be increased from 6 {times} 6 to 36 {times} 36 and finally to {approximately}100 {times} 100 bunches. The beam dynamics of the Tevatron has been studied from Beam-Beam effect point of view in a ``Strong-Weak`` representation with a single particle being tracked in presence of other beam. This paper describes the beam-beam effect in 6 {times} 6 operation of Tevatron.

Mishra, C.S.; Assadi, S. [Fermi National Accelerator Lab., Batavia, IL (United States); Talman, R. [Cornell Univ., Ithaca, NY (United States)

1995-08-01T23:59:59.000Z

379

Molecular Science Computing | EMSL  

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

Molecular Science Computing Overview Cell Isolation and Systems Analysis Deposition and Microfabrication Mass Spectrometry Microscopy Molecular Science Computing NMR and EPR...

380

SSRL BEAM PORT SCHEDULE  

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

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

SSRL BEAM PORT SCHEDULE  

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

382

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

383

LANL: Ion Beam Materials Laboratory  

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

384

High flux photon beam monitor  

SciTech Connect (OSTI)

We have designed two photon beam position monitors for use on our x-ray storage ring beam lines. In both designs, a pair of tungsten blades, separated by a pre-determined gap, intercepts a small fraction of the incoming beam. Due to photoemission, an electrical signal is generated which is proportional to the amount of beam intercepted. The thermal load deposited in the blade is transferred by a heat pipe to a heat exchanger outside the vacuum chamber. A prototype monitor with gap adjustment capability was fabricated and tested at a uv beam line. The results show that the generated electrical signal is a good measurement of the photon beam position. In the following sections, design features and test results are discussed.

Mortazavi, P.; Woodle, M.; Rarback, H.; Shu, D.; Howells, M.

1985-01-01T23:59:59.000Z

385

Particle Detector / Beam Current Transformer  

E-Print Network [OSTI]

Particle Detector / Beam Current Transformer Analysis December 8, 2009 Harold G. Kirk #12;ShotSignal,A.U. Proton Bunch Number Beam Current Transformer - 17011 0 2 4 6 8 0 2 4 6 8 10 12 14 16 18 20 Integrated Transformer Pump 187829 (au) Probe 196504 (au) Ratios: Beam Current 1.046 SF 1.019 2.9% difference #12;Shot

McDonald, Kirk

386

A pencil beam algorithm for helium ion beam therapy  

SciTech Connect (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

387

The Gas Flow from the Gas Attenuator to the Beam Line  

SciTech Connect (OSTI)

The gas leak from the gas attenuator to the main beam line of the Linac Coherent Light Source has been evaluated, with the effect of the Knudsen molecular beam included. It has been found that the gas leak from the gas attenuator of the present design, with nitrogen as a working gas, does not exceed 10{sup -5} torr x l/s even at the highest pressure in the main attenuation cell (20 torr).

Ryutov, D.D.

2010-12-03T23:59:59.000Z

388

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

389

Low energy beta-beams  

E-Print Network [OSTI]

The main goal of a beta-beam facility is to determine the possible existence of CP violation in the lepton sector, the value of the third neutrino mixing angle and the mass hierarchy. Here we argue that a much broader physics case can be covered since the beta-beam concept can also be used to establish a low energy beta-beam facility. We discuss that the availability of neutrino beams in the 100 MeV energy range offers a unique opportunity to perform neutrino scattering experiments of interest for nuclear physics, for the study of fundamental interactions and of core-collapse supernova physics.

Cristina Volpe

2009-11-13T23:59:59.000Z

390

ANL Beams and Applications Seminar  

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

Argonne Beams & Applications Seminar Search APS ... Search Argonne Home > Argonne Home > Advanced Photon Source > Seminar Archive 2012 2011 2010 2009 2008 2007 2006 2005 2004 2003...

391

Accelerators, Beams And Physical Review Special Topics - Accelerators And Beams  

SciTech Connect (OSTI)

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

392

Useful Graphs and Charts - Ion Beams - Radiation Effects Facility...  

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

Ion Beams Available Beams Beam Change Times Measurements Useful Graphs Useful Graphs and Charts LET vs. Range in Si Graphs: 15 MeVu Beams 24.8 MeVu Beams 40 MeVu Beams...

393

SSRL BEAM PORT SCHEDULE  

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

394

SSRL BEAM PORT SCHEDULE  

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

395

SSRL BEAM PORT SCHEDULE  

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

396

SSRL BEAM PORT SCHEDULE  

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

397

SSRL BEAM PORT SCHEDULE  

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

398

SSRL BEAM PORT SCHEDULE  

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

399

SSRL BEAM PORT SCHEDULE  

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

400

SSRL BEAM PORT SCHEDULE  

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

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

Tunable source of terahertz radiation using molecular modulation  

E-Print Network [OSTI]

Tunable source of terahertz radiation using molecular modulation D. D. Yavuz* and J. J. Weber a high power and widely tunable coher- ent source of THz radiation remains a very challenging task of terahertz (THz) radiation that is based on Raman down-shifting of an infrared laser beam using highly

Yavuz, Deniz

402

Laser acceleration of ion beams  

E-Print Network [OSTI]

We consider methods of charged particle acceleration by means of high-intensity lasers. As an application we discuss a laser booster for heavy ion beams provided, e.g. by the Dubna nuclotron. Simple estimates show that a cascade of crossed laser beams would be necessary to provide additional acceleration to gold ions of the order of GeV/nucleon.

I. A. Egorova; A. V. Filatov; A. V. Prozorkevich; S. A. Smolyansky; D. B. Blaschke; M. Chubaryan

2007-02-01T23:59:59.000Z

403

Broad-band beam buncher  

DOE Patents [OSTI]

A broad-band beam bunther 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-

Goldberg, D.A.; Flood, W.S.; Arthur, A.A.; Voelker, F.

1984-03-20T23:59:59.000Z

404

Measurements of aperture and beam lifetime using movable beam scrapers in Indus-2 electron storage ring  

SciTech Connect (OSTI)

In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.

Kumar, Pradeep; Ghodke, A. D.; Karnewar, A. K.; Holikatti, A. C.; Yadav, S.; Puntambekar, T. A.; Singh, G. [Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)] [Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Singh, P. [Bhabha Atomic Research Centre, Mumbai (India)] [Bhabha Atomic Research Centre, Mumbai (India)

2013-12-15T23:59:59.000Z

405

Epitaxial Pb(Zr, Ti)O3 thin films with coexisting tetragonal and rhombohedral phases  

Science Journals Connector (OSTI)

Epitaxial Pb(Zr, Ti)O3 thin films having coexisting tetragonal and rhombohedral phases have been successfully fabricated with the film compositions that correspond to the Zr-rich region of the morphotropic phase boundary (MPB). The key to the present success is to quantitatively understand the shift of the MPB under a film stress. The present fabrication has been theoretically justified by superimposing the computed temperature-dependent film stress on the theoretical temperature-stress (T-S) phase diagram and by delineating a probable phase-transition path upon cooling the film from the processing temperature.

S. Hoon Oh and Hyun M. Jang

2001-03-12T23:59:59.000Z

406

Fundamental optical properties of InN grown by epitaxial lateral overgrowth method  

SciTech Connect (OSTI)

Optical properties of InN grown by the epitaxial lateral overgrowth (ELO) method have been studied using photoluminescence (PL) and excitation-correlation (EC) measurements. The PL spectrum is analyzed by free-electron recombination band (FERB) model, which shows that the ELO sample has a very low background carrier concentration (n=5.5*10{sup 16}[cm{sup ?3]}). EC measurements show that the dependences of the band gap renormalization and Auger effect on the carrier concentrations are similar in spite of the different physical origins.

Kametani, Tatsuma; Kamimura, Jumpei; Inose, Yuta; Kunugita, Hideyuki; Kikuchi, Akihiko; Kishino, Katsumi; Ema, Kazuhiro [Department of Engineering and Applied Science, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan)

2013-12-04T23:59:59.000Z

407

An 8-{mu}m quantum cascade laserproduced by the metalorganic vapour phase epitaxy method  

SciTech Connect (OSTI)

An 8-{mu}m quantum cascade laser is fabricated by the metalorganic vapour phase epitaxy method. A scheme of vertical transitions in a structure consisting of three quantum wells is used. The laser operates in a pulsed regime at temperatures up to 250 K. The threshold current density was about 3 kA cm{sup -2} and increased up to 6 kA cm{sup -2} at 250 K. The 1-{mu}s pulse power in the multimode regime was 45 mW at 77 K.

Zasavitskii, I I; Pashkeev, D A [P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation); Marmalyuk, Aleksandr A; Ryaboshtan, Yu L [M.F. Stel'makh Polyus Research and Development Institute, Moscow (Russian Federation); Mikaelyan, G T [OJSC Research and Manufacturing Enterprise 'Inject', Saratov (Russian Federation)

2010-02-28T23:59:59.000Z

408

Epitaxial growth of aligned AlGalnN nanowires by metal-organic chemical vapor deposition  

DOE Patents [OSTI]

Highly ordered and aligned epitaxy of III-Nitride nanowires is demonstrated in this work. <1010> M-axis is identified as a preferential nanowire growth direction through a detailed study of GaN/AlN trunk/branch nanostructures by transmission electron microscopy. Crystallographic selectivity can be used to achieve spatial and orientational control of nanowire growth. Vertically aligned (Al)GaN nanowires are prepared on M-plane AlN substrates. Horizontally ordered nanowires, extending from the M-plane sidewalls of GaN hexagonal mesas or islands demonstrate new opportunities for self-aligned nanowire devices, interconnects, and networks.

Han, Jung (Woodbridge, CT); Su, Jie (New Haven, CT)

2008-08-05T23:59:59.000Z

409

Excess conductivity in 2:2:1:2-phase Bi-Sr-Ca-Cu-O epitaxial thin films  

Science Journals Connector (OSTI)

Measurements of the excess conductivity above the transition temperature on selected, high-quality, superconducting epitaxial films of the 2:2:1:2-phase Bi-Sr-Ca-Cu-O (BSCCO), obtained by liquid-phase epitaxy, are reported. The data confirm the two-dimensional nature of the thermodynamical fluctuations in BSCCO compounds in a wide range of temperature above Tc and very good agreement is found with an extended version of the Aslamazov-Larkin theory [L. Reggiani, R. Vaglio, and A. A. Varlamov, Phys. Rev. B 44, 9541 (1991)].

G. Balestrino; M. Marinelli; E. Milani; Lucia Reggiani; R. Vaglio; A. A. Varlamov

1992-12-01T23:59:59.000Z

410

IonBeamMicroFab  

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

411

Time Structure of the LANSCE Beam  

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

Beam One of the greatest strengths of the LANSCE facility is that it can produce proton beams with a wide range of time structures. Time Structure of the LANSCE Beam One of the...

412

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

413

Ferromagnetism in Mn-Implanted Epitaxially Grown Ge on Si(100)  

SciTech Connect (OSTI)

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

414

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

415

Anisotropy of the solid-state epitaxy of silicon carbide in silicon  

SciTech Connect (OSTI)

A new method for the solid-state synthesis of epitaxial layers is developed, in which a substrate participates in the chemical reaction and the reaction product grows not on the substrate surface, as in traditional epitaxial methods, but inside the substrate. This method offers new opportunities for elastic-energy relaxation due to a mechanism operating only in anisotropic media, specifically, the attraction of point defects formed during the chemical reaction. The attracting point centers of dilatation form relatively stable objects, dilatation dipoles, which significantly reduce the total elastic energy. It is shown that, in crystals with cubic symmetry, the most favorable arrangement of dipoles is the ?111? direction. The theory is tested by growing silicon carbide (SiC) films on Si (111) substrates by chemical reaction with carbon monoxide CO. High-quality single-crystal SiC-4H films with thicknesses of up to 100 nm are grown on Si (111). Ellipsometric analysis showed that the optical constants of the SiC-4H films are significantly anisotropic. This is caused not only by the lattice hexagonality but also by a small amount (about 2–6%) of carbon atoms remaining in the film due to dilatation dipoles. It is shown that the optical constants of the carbon impurity correspond to strongly anisotropic highly oriented pyrolytic graphite.

Kukushkin, S. A., E-mail: kukushkin_s@yahoo.com; Osipov, A. V. [Russian Academy of Sciences, Institute of Problems of Machine Science (Russian Federation)

2013-12-15T23:59:59.000Z

416

Asymmetric Electron Transport at Monolayer-Bilayer Heterojunctions of Epitaxial Graphene  

SciTech Connect (OSTI)

The symmetry of the graphene honeycomb lattice is a key element determining many of graphene s unique electronic properties, such as the linear energy-momentum dispersion and the suppressed backscattering 1,2. However, line defects in large-scale epitaxial graphene films, such as grain boundaries, edges, surface steps, and changes in layer thickness, often break the sublatttice symmetry and can impact transport properties of graphene profoundly 3-6. Here we report asymmetric electron transport upon polarity reversal at individual monolayer-bilayer (ML-BL) boundaries in epitaxial graphene on SiC (0001), revealed by scanning tunneling potentiometry. A greater voltage drop is observed when the current flows from BL to ML graphene than in the reverse direction, and the difference remains nearly unchanged with increasing current. This is not a typical nonlinear conductance due to electron transmission through an asymmetric potential. Rather, it indicates the opening of a dynamic energy gap at the Fermi energy due to the Coulomb interaction between the injected nonequilibrium electron density and the pseudospin polarized Friedel oscillation charge density at the boundary. This intriguing heterojunction transport behavior opens a new avenue towards novel quantum functions such as quantum switching.

Li, An-Ping [ORNL] [ORNL; Clark, Kendal W [ORNL] [ORNL; Zhang, Xiaoguang [ORNL] [ORNL; Gu, Gong [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK); He, Guowei [Carnegie Mellon University (CMU)] [Carnegie Mellon University (CMU); Feenstra, Randall [Carnegie Mellon University (CMU)] [Carnegie Mellon University (CMU)

2014-01-01T23:59:59.000Z

417

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

418

SSRL BEAM PORT SCHEDULE  

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

419

SSRL BEAM PORT SCHEDULE  

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

420

SSRL BEAM PORT SCHEDULE  

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

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

SSRL BEAM PORT SCHEDULE  

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

422

Probing Organic Transistors with Infrared Beams  

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

Probing Organic Transistors with Infrared Beams Probing Organic Transistors with Infrared Beams Print Wednesday, 26 July 2006 00:00 Silicon-based transistors are well-understood,...

423

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

424

Alight a beam and beaming light: A theme with variations  

SciTech Connect (OSTI)

The interaction of light (coherent and incoherent) with charged particle beams is explored in various configurations: incoherent scattering of coherent light (laser) from an incoherent particle beam (high temperature), coherent scattering of coherent light (laser) from a {open_quotes}cold{close_quotes} (bunched) beam, femtosecond generation of particle and light beams via {open_quotes}optical slicing{close_quotes} and Thomson/Compton scattering techniques, etc. The domains of ultrashort temporal duration (femtoseconds) as well as ultrashort wavelengths (x rays and shorter), with varying degrees of coherence, are explored. The relevance to a few critical areas of research in the natural sciences, e.g., ultrafast material, chemical and biological processes, protein folding, particle phase space cooling, etc. are touched upon. All the processes discussed involve proper interpretation and understanding of coherent states of matter and radiation, as well as the quality and quantity of information and energy embedded in them. {copyright} {ital 1998 American Institute of Physics.}

Chattopadhyay, S. [Ernest Orlando Lawrence Berkeley National Laboratory, University of California, Berkeley, California94720 (United States)] [Ernest Orlando Lawrence Berkeley National Laboratory, University of California, Berkeley, California94720 (United States)

1998-05-01T23:59:59.000Z

425

Electron beam machining using rotating and shaped beam power distribution  

DOE Patents [OSTI]

An apparatus and method are disclosed 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 1,000 {micro}m (1 mm or larger), compared to the 250 {micro}m diameter of laser drilling. 5 figs.

Elmer, J.W.; O`Brien, D.W.

1996-07-09T23:59:59.000Z

426

Diagnostic beam absorber in Mu2e beam line  

SciTech Connect (OSTI)

Star density, hadron flux, and residual dose distributions are calculated around the {mu}2e diagnostic beam absorber. Corresponding surface and ground water activation, and air activation are presented as well.

Rakhno, Igor; /Fermilab

2011-03-01T23:59:59.000Z

427

EMSL - Molecular Science Computing  

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

computing Resources and Techniques Molecular Science Computing - Sophisticated and integrated computational capabilities, including scientific consultants, software, Cascade...

428

Molecular vibration demonstrations  

Science Journals Connector (OSTI)

Molecular vibration demonstrations ... Two dynamic models that illustrate the normal-mode vibrations of the water and benzene molecules. ...

George Turrell; Robert Demol

1987-01-01T23:59:59.000Z

429

Hole transport and doping states in epitaxial CuIn1 xGaxSe2 David J. Schroeder  

E-Print Network [OSTI]

interest in renewable energy sources such as photovoltaic devices. CuIn1 xGaxSe2 CIGS /CdS hetero- junctionHole transport and doping states in epitaxial CuIn1 xGaxSe2 David J. Schroeder Motorola

Rockett, Angus

430

Inverted List Kinetic Monte Carlo with Rejection ap-plied to Directed Self-Assembly of Epitaxial Growth  

E-Print Network [OSTI]

Inverted List Kinetic Monte Carlo with Rejection ap- plied to Directed Self-Assembly of Epitaxial of subsequently deposited material using a kinetic Monte Carlo algorithm that combines the use of inverted lists finding is that the relative performance of the inverted list algorithm improves with increasing system

Schulze, Tim

431

CdTe EPITAXIAL FILMS AND THEIR PROPERTIES S. N. MAXIMOVSKY, I. P. REVOCATOVA, V. M. SALMAN,  

E-Print Network [OSTI]

161 CdTe EPITAXIAL FILMS AND THEIR PROPERTIES S. N. MAXIMOVSKY, I. P. REVOCATOVA, V. M. SALMAN, M CdTe films of p and n type conductivity with a given devia- tion of film composition from PHYSIQUE APPLIQUÃ?E TOME 12, FÃ?VRIER 1977, PAGE 161 The design of reliable CdTe nuclear radiation counters

Paris-Sud XI, Université de

432

PUBLISHED ONLINE: 24 JULY 2011 | DOI: 10.1038/NMAT3071 Epitaxial growth of three-dimensionally  

E-Print Network [OSTI]

-dimensionally architectured optoelectronic devices Erik C. Nelson1 , Neville L. Dias2 , Kevin P. Bassett2 , Simon N. Dunham1 and Paul V. Braun1 * Optoelectronic devices have long benefited from structuring in multiple dimensions-template-directed epitaxy of group III­V materials, which enables formation of 3D structured optoelectronic devices. We

Rogers, John A.

433

Comprehensive study of the metal-insulator transition in pulsed laser deposited epitaxial VO2 thin films  

E-Print Network [OSTI]

Comprehensive study of the metal-insulator transition in pulsed laser deposited epitaxial VO2 thin properties of high-quality VO2 thin films across its metal-insulator phase transition. Detailed x-ray deposition,9 sol-gel deriving,10 sputtering,11 and pulsed laser deposition,12 the study of VO2 is reviving

Wu, Junqiao

434

Field effect in epitaxial graphene on a silicon carbide substrate Sarnoff Corporation, CN5300, Princeton, New Jersey 08543  

E-Print Network [OSTI]

deposition on the surfaces of transition metal or transition metal carbide single crystals, and the physical on a graphitized SiC surface, as opposed to highly conductive metal and metal carbide substrates that require1 Field effect in epitaxial graphene on a silicon carbide substrate Gong Gua) Sarnoff Corporation

Feenstra, Randall

435

Generation and Recombination Carrier Lifetimes in 4H SiC Epitaxial Wafers , M. J. Loboda1)  

E-Print Network [OSTI]

Generation and Recombination Carrier Lifetimes in 4H SiC Epitaxial Wafers G. Chung1) , M. J. Loboda comparative studies of recombination and carrier lifetimes in SiC. For the first time, both generation-wafer structures. The ratio of the generation to recombination lifetime is much different in SiC compared to Si

Schroder, Dieter K.

436

The Beam | Open Energy Information  

Open Energy Info (EERE)

Zip: 2446 Product: The Beam is a start-up company that looks to establish an online retail portal that would market and sell clean energy-related products to consumers....

437

STOCHASTIC COOLING FOR BUNCHED BEAMS.  

SciTech Connect (OSTI)

Problems associated with bunched beam stochastic cooling are reviewed. A longitudinal stochastic cooling system for RHIC is under construction and has been partially commissioned. The state of the system and future plans are discussed.

BLASKIEWICZ, M.

2005-05-16T23:59:59.000Z

438

Center for Beam Physics, 1992  

SciTech Connect (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

439

Neutron beam testing of triblades  

SciTech Connect (OSTI)

PowerXCell 8i processors and Opterons in four IBM Triblades were tested at LANSCE. The hazard rate when the beam was aimed at the Opterons was higher than when it was aimed at the Cell processors.

Michalak, Sarah E [Los Alamos National Laboratory; Du Bois, Andrew J [Los Alamos National Laboratory; Storlie, Curtis B [Los Alamos National Laboratory; Rust, William N [Los Alamos National Laboratory; Du Bois, David H [Los Alamos National Laboratory; Modl, David G [Los Alamos National Laboratory; Quinn, Heather M [Los Alamos National Laboratory; Blanchard, Sean P [Los Alamos National Laboratory; Manuzzato, Andrea [UNIV DEGLI STUDI DI PADOVA ITALY

2011-01-31T23:59:59.000Z

440

Neon Ion Beam Lithography (NIBL)  

E-Print Network [OSTI]

Existing techniques for electron- and ion-beam lithography, routinely employed for nanoscale device fabrication and mask/mold prototyping, do not simultaneously achieve efficient (low fluence) exposure and high resolution. ...

Winston, Donald

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

Beam bunch feedback  

SciTech Connect (OSTI)

When the electromagnetic fields that are excited by the passage of a bundle of charged particles persist to act upon bunches that follow, then the motions of the bunches are coupled. This action between bunches circulating on a closed orbit can generate growing patterns of bunch excursions. Such growth can often be suppressed by feedback systems that detect the excursion and apply corrective forces to the bunches. To be addressed herein is feedback that acts on motions of the bunch body centers. In addition to being useful for suppressing the spontaneous growth of coupled-bunch motions, such feedback can be used to damp transients in bunches injected into an accelerator or storage ring; for hadrons which lack strong radiation damping, feedback is needed to avoid emittance growth through decoherence. Motions excited by noise in magnetic fields or accelerating rf can also be reduced by using this feedback. Whether the action is on motions that are transverse to the closed orbit or longitudinal, the arrangement is the same. Bunch position is detected by a pickup and that signal is processed and directed to a kicker that may act upon the same bunch or some other portion of the collective beam pattern. Transverse motion is an oscillation with angular frequency {nu}{perpendicular}{omega}{sub o} where {omega}{sub o} is the orbital frequency 2{pi}{line_integral}o. Longitudinal synchrotron oscillation occurs at frequency {omega} {sub s} = {nu}{sub s}{omega}{sub o}. The former is much more rapid, {nu}{perpendicular} being on the order of 10 while {nu}{sub s} is typically about 10{sup minus 1} to 10 {sup minus 2}.

Lambertson, G.

1995-09-01T23:59:59.000Z

442

Much simplified ion-beam assisted deposition-TiN template for high-performance coated conductors  

SciTech Connect (OSTI)

A much simplified template, i.e., two nonsuperconducting layers between the superconducting YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) and the polycrystalline metal substrate, has been developed for high-performance coated conductors by using biaxially aligned TiN as a seed layer. A combination of a thin TiN ({approx}10 nm by ion-beam assisted deposition) layer and an epitaxial buffer LaMnO{sub 3} layer ({approx}120 nm) allows us to grow epitaxial YBCO films with values of full width at half-maximum around 3.5 deg. and 1.7 deg. for the {phi}-scan of (103) and rocking curve of (005) YBCO, respectively. The YBCO films grown on electropolished polycrystalline Hastelloy using this two-layer template exhibited a superconducting transition temperature of 89.5 K, a critical current density of 1.2 MA/cm{sup 2} at 75.5 K, and an {alpha} value (proportional factor of critical current density J{sub c}{approx}H{sup -}{alpha}) of around 0.33, indicating a high density of pinning centers and an absence of weak links.

Xiong, J. [Division of Materials Physics and Applications, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); State Key Lab of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Matias, V.; Zhai, J. Y.; Maiorov, B.; Trugman, D.; Jia, Q. X. [Division of Materials Physics and Applications, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Wang, H. [Department of Electrical and Computer Engineering, Texas A and M University, College Station, Texas 77843-3128 (United States); Tao, B. W.; Li, Y. R. [State Key Lab of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2010-10-15T23:59:59.000Z

443

Electron beam diagnostic for profiling high power beams  

DOE Patents [OSTI]

A system for characterizing high power electron beams at power levels of 10 kW and above is described. This system is comprised of a slit disk assembly having a multitude of radial slits, a conducting disk with the same number of radial slits located below the slit disk assembly, a Faraday cup assembly located below the conducting disk, and a start-stop target located proximate the slit disk assembly. In order to keep the system from over-heating during use, a heat sink is placed in close proximity to the components discussed above, and an active cooling system, using water, for example, can be integrated into the heat sink. During use, the high power beam is initially directed onto a start-stop target and after reaching its full power is translated around the slit disk assembly, wherein the beam enters the radial slits and the conducting disk radial slits and is detected at the Faraday cup assembly. A trigger probe assembly can also be integrated into the system in order to aid in the determination of the proper orientation of the beam during reconstruction. After passing over each of the slits, the beam is then rapidly translated back to the start-stop target to minimize the amount of time that the high power beam comes in contact with the slit disk assembly. The data obtained by the system is then transferred into a computer system, where a computer tomography algorithm is used to reconstruct the power density distribution of the beam.

Elmer, John W. (Danville, CA); Palmer, Todd A. (Livermore, CA); Teruya, Alan T. (Livermore, CA)

2008-03-25T23:59:59.000Z

444

MEIS: Molecular Environmental & Interface Science  

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

445

A Timoshenko beam theory with pressure corrections for layered orthotropic beams  

E-Print Network [OSTI]

A Timoshenko beam theory with pressure corrections for layered orthotropic beams Graeme J. Kennedya of Michigan, Ann Arbor, MI 48109, USA Abstract A Timoshenko beam theory for layered orthotropic beams and rotation variables that provide the kinematic description of the beam, stress and strain moments used

Papalambros, Panos

446

Physics Reach of the Beta Beam  

E-Print Network [OSTI]

Beta Beams are designed to produce pure (anti)electron neutrino beams and could be an elegant and powerful option for the search of leptonic CP violating processes. In this paper will be quantified the physics reach of a CERN based Beta Beam and of a Super Beam - Beta Beam combination. The CP phase $\\delta$ sensitivity results to be comparable to a Neutrino Factory for $\\sin^2{\\theta_{13}}$ values greater than $10^{-4}$.

Mauro Mezzetto

2003-02-07T23:59:59.000Z

447

Growth of vertical-cavity surface emitting lasers by metalorganic vapor phase epitaxy  

SciTech Connect (OSTI)

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

448

Identification of dominant scattering mechanism in epitaxial graphene on SiC  

SciTech Connect (OSTI)

A scheme of identification of scattering mechanisms in epitaxial graphene (EG) on SiC substrate is developed and applied to three EG samples grown on SiC (0001), (112{sup ¯}0), and (101{sup ¯}0) substrates. Hall measurements combined with defect detection technique enable us to evaluate the individual contributions to the carrier scatterings by defects and by substrates. It is found that the dominant scatterings can be due to either substrate or defects, dependent on the substrate orientations. The EG on SiC (112{sup ¯}0) exhibits a better control over the two major scattering mechanisms and achieves the highest mobility even with a high carrier concentration, promising for high performance graphene-based electronic devices. The method developed here will shed light on major aspects in governing carrier transport in EG to harness it effectively.

Lin, Jingjing; Guo, Liwei, E-mail: lwguo@iphy.ac.cn, E-mail: chenx29@aphy.iphy.ac.cn; Jia, Yuping; Huang, Jiao; Guo, Yu; Li, Zhilin; Chen, Xiaolong, E-mail: lwguo@iphy.ac.cn, E-mail: chenx29@aphy.iphy.ac.cn [Research and Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190 (China); Yang, Rong; Wu, Shuang; Zhang, Guangyu [Nanoscale Physics and Devices Laboratory, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190 (China)

2014-05-05T23:59:59.000Z

449

FeP precipitates in hydride?vapor phase epitaxially grown InP:Fe  

Science Journals Connector (OSTI)

Fe?doped InP was grown by hydride?vapor phase epitaxy.Doping levels up to 8×1018 cm?3 were determined by secondary ion mass spectrometry. Additionally performed photoluminescence measurements revealed a homogeneous distribution of electrically active Fe atoms. From microstructural investigations by analytical transmission electron microscopy spherical?shaped precipitates were detected in plan?view samples. These precipitates with diameters up to 13 nm are homogeneously arranged in the epilayer. For conglomerates of precipitates a distinct enrichment with Fe and P was measured by a comparative energy dispersive x?ray analysis. The lattice plane distances of the precipitates were deduced from the electron diffraction patterns and from high?resolution electron micrographs. A comparison with calculated values for different Fe–P alloys indicates that the precipitates consist mainly of orthorhombic FeP.

M. Luysberg; R. Göbel; H. Janning

1994-01-01T23:59:59.000Z

450

Materials basis for a six-level epitaxial HTS digital circuit process  

SciTech Connect (OSTI)

We have developed a process for fabrication of HTS single-flux-quantum logic circuits based on edge SNS junctions which requires six epitaxial film layers and six mask levels. The process was successfully applied to fabrication of small-scale circuits ({le} 10 junctions). This paper examines the materials properties affecting the reproducibility of YBCO-based SNS junctions, the low inductance provided by an integrated YBCO ground plane, and electrical isolation by SrTiO{sub 3} or SrAlTaO{sub 6} ground-plane and junction insulator layers. Some of the critical processing parameters identified by electrical measurements, TEM, SEM, and AFM were control of second-phase precipitates in YBCO, oxygen diffusion, Ar ion milling parameters, and preparation of surfaces for subsequent high-temperature depositions.

Talvacchio, J.; Forrester, M.G.; Hunt, B.D. [Northrop Grumman Science and Technology Center, Pittsburgh, PA (United States)] [and others

1996-12-31T23:59:59.000Z

451

High-temperature thermoelectric response of double-doped SrTiO3 epitaxial films  

Science Journals Connector (OSTI)

SrTiO3 is a promising n-type oxide semiconductor for thermoelectric energy conversion. Epitaxial thin films of SrTiO3 doped with both La and oxygen vacancies have been synthesized by pulsed laser deposition. The thermoelectric and galvanomagnetic properties of these films have been characterized at temperatures ranging from 300 to 900 K and are typical of a doped semiconductor. Thermopower values of double-doped films are comparable to previous studies of La-doped single crystals at similar carrier concentrations. The highest thermoelectric figure of merit (ZT) was measured to be 0.28 at 873 K at a carrier concentration of 2.5×1021?cm?3.

J. Ravichandran; W. Siemons; D.-W. Oh; J. T. Kardel; A. Chari; H. Heijmerikx; M. L. Scullin; A. Majumdar; R. Ramesh; D. G. Cahill

2010-10-28T23:59:59.000Z

452

Achieving clean epitaxial graphene surfaces suitable for device applications by improved lithographic process  

SciTech Connect (OSTI)

It is well-known that the performance of graphene electronic devices is often limited by extrinsic scattering related to resist residue from transfer, lithography, and other processes. Here, we report a polymer-assisted fabrication procedure that produces a clean graphene surface following device fabrication by a standard lithography process. The effectiveness of this improved lithography process is demonstrated by examining the temperature dependence of epitaxial graphene-metal contact resistance using the transfer length method for Ti/Au (10?nm/50?nm) metallization. The Landauer-Buttiker model was used to explain carrier transport at the graphene-metal interface as a function of temperature. At room temperature, a contact resistance of 140 ?-?m was obtained after a thermal anneal at 523?K for 2?hr under vacuum, which is comparable to state-of-the-art values.

Nath, A., E-mail: anath@gmu.edu; Rao, M. V. [George Mason University, 4400 University Dr., Fairfax, Virginia 22030 (United States); Koehler, A. D.; Jernigan, G. G.; Wheeler, V. D.; Hite, J. K.; Hernández, S. C.; Robinson, Z. R.; Myers-Ward, R. L.; Eddy, C. R.; Gaskill, D. K. [U.S. Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, D.C. 20375 (United States); Garces, N. Y. [Sotera Defense Solutions, 2200 Defense Hwy. Suite 405, Crofton, Maryland 21114 (United States)

2014-06-02T23:59:59.000Z

453

Selective adsorption and electronic interaction of F16CuPc on epitaxial graphene  

Science Journals Connector (OSTI)

We investigate the electronic coupling between copper hexadecafluoro-phthalocyanine (F16CuPc) and epitaxial graphene (EG) on 6H-SiC(0001) using a combined approach of low-temperature scanning tunneling spectroscopy and electronic structure calculations. The molecules are preferentially adsorbed on monolayer EG than bilayer EG. Competing molecule-surface and intermolecular van der Waals interactions result in two well-ordered incommensurate phases. We show that the amount of charge transfer from EG to F16CuPc can be tuned by applied voltage or the thickness of graphene layers. A characteristic feature at ?0.4?eV above the Dirac point is identified in bilayer EG, which indicates its electronic structure is modified via introducing extra unoccupied states upon adsorption.

Yi-Lin Wang; Jun Ren; Can-Li Song; Ye-Ping Jiang; Li-Li Wang; Ke He; Xi Chen; Jin-Feng Jia; Sheng Meng; Efthimios Kaxiras; Qi-Kun Xue; Xu-Cun Ma

2010-12-14T23:59:59.000Z

454

Electrical properties of the amorphous interfacial layer between Al electrodes and epitaxial NiO films  

SciTech Connect (OSTI)

The amorphous interfacial layer (a-IL) between Al electrode and epitaxial NiO films were studied using electron energy-loss spectroscopy (EELS) and energy-dispersive x-ray spectroscopy. Two distinct properties were found in the a-IL, i.e., a lower metallic and an upper insulating layer. EELS results revealed that the metallic Ni atoms were responsible for the conducting nature of the lower oxide amorphous layer. The resistance behavior of Al/a-IL/epi-NiO was changed from a high to a low resistance state after forming process. The resistance change could be explained by the formation of a nanocrystalline metal alloy in the insulating amorphous layer.

Hyuck Jang, Jae; Kwon, Ji-Hwan; Kim, Miyoung [Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Ran Lee, Seung; Char, Kookrin [Department of Physics and Astronomy and Center for Strongly Correlated Materials Research, Seoul National University, Seoul 151-747 (Korea, Republic of)

2012-04-23T23:59:59.000Z

455

Epitaxial growth of 3C-SiC by pulsed laser deposition  

SciTech Connect (OSTI)

The attractiveness of SiC as an advanced semiconducting material derives from its many superior properties such as high breakdown voltage, high saturated electron drift velocity, high thermal conductivity and resistance to high temperature effects. The authors have grown thin films of SiC by pulsed laser deposition on silicon (100) and vicinal and non-vicinal 6H SiC (0001) substrates using a quadrupled YAG laser and a high purity dense polycrystalline SiC target. Epitaxy on all three substrate types was confirmed by x-ray diffraction, transmission electron microscopy and electron diffraction. Composition of the films was measured by Rutherford backscattering spectrometry and Scanning Auger Microprobe.

Cosgrove, J.E.; Rosenthal, P.A.; Hamblen, D.; Fenner, D.B. [Advanced Fuel Research, Inc., East Hartford, CT (United States); Yang, C. [Santa Clara Univ., CA (United States)

1996-12-31T23:59:59.000Z

456

Relaxation of crystal lattice parameters and structural ordering in In{sub x}Ga{sub 1-x}As epitaxial alloys  

SciTech Connect (OSTI)

Epitaxial In{sub x}Ga{sub 1-x}As/GaAs(100) heterostructures grown by the MOC-hydride method with a considerable lattice mismatch are studied by X-ray diffraction and scanning electron microscopy. The relaxation coefficient of the crystal lattice of the epitaxial alloy is calculated and the deformation energy is evaluated. It is shown that, at a concentration of the In atoms in metal sublattice close to x = 0.5, the superstructural phase formed on the surface of the epitaxial In{sub x}Ga{sub 1-x}As alloy is the InGaAs{sub 2} compound with a layered tetragonal crystal lattice and ordered arrangement of the atoms of the metal sublattice in the growth plane of the epitaxial film.

Seredin, P. V., E-mail: paul@phys.vsu.ru; Glotov, A. V.; Domashevskaya, E. P. [Voronezh State University (Russian Federation); Arsentyev, I. N., E-mail: arsentyev@mail.ioffe.ru; Vinokurov, D. A. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Stankevich, A. L.; Tarasov, I. S. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation)

2010-08-15T23:59:59.000Z

457

Machine and Beam Delivery Updates  

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

MAchine and Beam delivery Updates FY13 MAchine and Beam delivery Updates FY13 Summary of Beam Delivery: FACET Summary Feb_15_22.pdf FACET Summary Feb_15_22.pdf FACET Summary Feb_23_Mar_1.pdf FACET Summary Feb_23_Mar_1.pdf FACET Summary Mar_2_8.pdf FACET Summary Mar_2_8.pdf FACET Summary Mar_9_15.pdf FACET Summary Mar_9_15.pdf FACET Summary Mar_16_22.pdf FACET Summary Mar_16_22.pdf FACET Summary Mar_23_29.pdf FACET Summary Mar_23_29.pdf FACET Summary Mar_30_Apr_5.pdf FACET Summary Mar_30_Apr_5.pdf FACET Summary Apr_6_12.pdf FACET Summary Apr_6_12.pdf FACET Summary Apr_27_May_3.pdf FACET Summary Apr_27_May_3.pdf FACET Summary May_4_10.pdf FACET Summary May_4_10.pdf Emittance Stability in Sector 2_31513.pdf Emittance Stability in Sector 2_31513.pdf FACET beam operations readiness with R56.pdf FACET beam operations readiness with R56.pdf (6/19/2013)

458

Beam-plasma coupling effects on the stopping power of dense plasmas  

Science Journals Connector (OSTI)

The stopping power for ion beams in dense plasmas is investigated on the basis of quantum kinetic equations. Strong correlations between the beam ions and the plasma particles which occur for high ion charge numbers and strongly coupled plasmas are treated on the level of the statically screened T-matrix (binary collision) approximation. Dynamic screening effects are included using a combined scheme which considers both close collisions and collective effects. Applying this approach, the ion charge number dependence of the stopping power is determined. The result is a modification of the Zb2 scaling law. In particular, the stopping power is reduced for strong beam-plasma coupling. Good agreement is found between T-matrix results and simulation data (particle-in-cell and molecular dynamics) for low beam velocities.

D. O. Gericke and M. Schlanges

1999-07-01T23:59:59.000Z

459

Microstructure and Mechanics of Superconductor Epitaxy via the Chemical Solution Deposition Method  

SciTech Connect (OSTI)

Executive Summary: Initially the funds were sufficient funds were awarded to support one graduate student and one post-doc. Lange, though other funds, also supported a graduate intern from ETH Zurich, Switzerland for a period of 6 months. The initial direction was to study the chemical solution deposition method to understand the microstructural and mechanical phenomena that currently limit the production of thick film, reliable superconductor wires. The study was focused on producing thicker buffer layer(s) on Ni-alloy substrates produced by the RABiTS method. It focused on the development of the microstructure during epitaxy, and the mechanical phenomena that produce cracks during dip-coating, pyrolysis (decomposition of precursors during heating), crystallization and epitaxy. The initial direction of producing thicker layers of a know buffer layer material was redirected by co-workers at ORNL, in an attempt to epitaxially synthesize a potential buffer layer material, LaMnO3, via the solution route. After a more than a period of 6 months that showed that the LaMnO3 reacted with the Ni-W substrate at temperatures that could produce epitaxy, reviewers at the annual program review strongly recommended that the research was not yielding positive results. The only positive result presented at the meeting was that much thicker films could be produce by incorporating a polymer into the precursor that appeared to increase the precursor’s resistance to crack growth. Thus, to continue the program, the objectives were changed to find compositions with the perovskite structure that would be a) chemically compatible with either the Ni-W RABiTS or the MgO IBAD Ni-alloy substrates, and produce a better lattice parameter fit between either of the two substrates. At the start of the second year, the funding was reduced to 2/3’s of the first year level, which required the termination of the post-doc after approximately 5 months into the second year. From then on, further funding was intermittent to say the least, and funding to support the student and the research expenses has to be supplemented by Lange’s gift funds. During the first part of the second year, strontium zirconate was identified as an alternative to lanthanum manganite as a buffer layer for use on the IBAD MgO superconducting wire. A lattice parameter of 4.101 Angstroms offers a reduced lattice mismatch between the MgO and SrZrO3. Studies were focused on investigating hybrid precursor routes, combining Sr acetate with a number of different Zr alkoxides. Initial results from heat treating precursors to form powders are positive with the formation of orthorhombic SrZrO3 at temperatures between 800°C and 1100°C under a reducing atmosphere of Ar – 5% H2. Buffer layer research on RABiTS substrates were centered on GdAlO3 (3.71 Å) and YAlO3 (3.68 Å) buffer layer materials. Powder experiments in YAlO3 have shown the perovskite phase to be metastable at processing temperatures below 1500 °C. Experiments involving spin coating of YAlO3 precursors have found significant problems involved with wettability of the YAlO3 precursor (Yttrium acetate, Aluminum tri-sec butoxide, DI water and Formic Acid) on RABiTS substrates; this, and the demise of the funds precluded further research using YAlO3. The diminished funds for the second year, and the small, tricked funds during the third year lead to a redirection of the student to another research area., and a stop to any experimental achievements that were much too ambition relative to the available funds. The only positive results obtained during this latter period was the understanding why two dissimilar structures could result in an epitaxial relation. It was shown that two rules of crystal chemistry, cation/anion coordination and charge balance, could be applied to understand the epitaxy of SrTiO3 on Ni c(2 X 2)S, TiO2 (anatase) on LaAlO3, TiO2 (rutile) on r-plane Al2O3, and Zr1-x(Yx)O2 on (0001) Al2O3. This new understanding of the interface between two dissimilar structures has important implications that include the buff

Frederick F. Lange

2006-11-30T23:59:59.000Z

460

AFRD - Center for Beam Physics  

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

Center for Beam Physics Center for Beam Physics Home Organization Outreach and Diversity Highlights Safety Links Intramural Group photo of our staff CBP staff, May 2011 CBP in the News: Read about an innovation in super-precise timing and synchronization; and a look toward the next generation of electron guns with responsiveness and brightness needed by future free-electron lasers such as those in the Next Generation Light Source initiative. Who We Are and What We Do The Center for Beam Physics (CBP) is a resource for meeting the challenges of accelerator science, and a source of many innovative concepts, within the Accelerator and Fusion Research Division. We have core expertise in accelerator physics and theory, accelerator modeling using high performance computing, and instrumentation,

Note: This page contains sample records for the topic "molecular beam epitaxy" from the National Library of EnergyBeta (NLEBeta).
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461

The Beam Profile Calculation for Diagnostic Neutral Beam on HT-7 Tokamak  

Science Journals Connector (OSTI)

A new calculation method is introduced for convergence beam intensity. The program based on this method is prepared for beam intensity distribution and beam power calculation. Taking the HT-7 DNB as a referenc...

Lizhen Liang; Chundong Hu

2013-10-01T23:59:59.000Z

462

Effect of Beam-Beam Interactions on Stability of Coherent Oscillations in a Muon Collider  

SciTech Connect (OSTI)

In order to achieve peak luminosity of a muon collider in the 10{sup 34}/cm{sup 2}/s range the number of muons per bunch should be of the order of a few units of 10{sup 12} rendering the beam-beam parameter as high as 0.1 per IP. Such strong beam-beam interaction can be a source of instability if the working point is chosen close to a coherent beam-beam resonance. On the other hand, the beam-beam tunespread can provide a mechanism of suppression of the beam-wall driven instabilities. In this report the coherent instabilities driven by beam-beam and beam-wall interactions are studied with the help of BBSS code for the case of 1.5 TeV c.o.m muon collider.

Alexahin, Y.; /Fermilab; Ohmi, K.; /KEK, Tsukuba

2012-05-01T23:59:59.000Z

463

Survey of Collective Instabilities and Beam-Plasma Interactions in Intense Heavy Ion Beams  

E-Print Network [OSTI]

H. Qin, Phys. Rev. ST Accel. Beams 4, 104401 (2001). [30] S.Davidson, Phys. Rev. ST Accel. Beams 5, 021001 (2002). [31]Channell, Phys. Rev. ST Accel. Beams 2, 074401 (1999); [32

Davidson, Ronald C.

2009-01-01T23:59:59.000Z

464

Engineering Molecular Transformations  

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

Engineering Molecular Transformations for Sustainable Energy Conversion Matthew Neurock* Departments of Chemical Engineering and Chemistry, UniVersity of Virginia, CharlottesVille,...

465

Accelerated Molecular Dynamics Methods  

Broader source: Energy.gov [DOE]

This presentation on Accelerated Molecular Dynamics Methods was given at the DOE Theory Focus Session on Hydrogen Storage Materials on May 18, 2006.

466

Nonparaxial Mathieu and Weber accelerating beams  

E-Print Network [OSTI]

We demonstrate both theoretically and experimentally nonparaxial Mathieu and Weber accelerating beams, generalizing the concept of previously found accelerating beams. We show that such beams bend into large angles along circular, elliptical or parabolic trajectories but still retain nondiffracting and self-healing capabilities. The circular nonparaxial accelerating beams can be considered as a special case of the Mathieu accelerating beams, while an Airy beam is only a special case of the Weber beams at the paraxial limit. Not only generalized nonparaxial accelerating beams open up many possibilities of beam engineering for applications, but the fundamental concept developed here can be applied to other linear wave systems in nature, ranging from electromagnetic and elastic waves to matter waves.

Peng Zhang; Yi Hu; Tongcang Li; Drake Cannan; Xiaobo Yin; Roberto Morandotti; Zhigang Chen; Xiang Zhang

2012-10-23T23:59:59.000Z

467

Stochastic cooling of bunched beams  

SciTech Connect (OSTI)

Numerical simulation studies are presented for transverse and longitudinal stochastic cooling of bunched particle beams. Radio frequency buckets of various shapes (e.g. rectangular, parabolic well, single sinusoidal waveform) are used to investigate the enhancement of phase space cooling by nonlinearities of synchrotron motion. The connection between the notions of Landau damping for instabilities and mixing for stochastic cooling are discussed. In particular, the need for synchrotron frequency spread for both Landau damping and good mixing is seen to be comparable for bunched beams.

Bisognano, J.J.; Chattopadhyay, S.

1981-03-01T23:59:59.000Z

468

Thermal stresses in laminated beams  

E-Print Network [OSTI]

24. Normal Stress Distribution for a Cantilever Laminated Beam, T-Z sinzx/L --------------- 58 m. i 25. Axial Stress Distribution for a Cantilever Laminated Bearq, T-T (2z/8+1) 2 mi 27. Normal Stress Distribution for ("/L) ? ---- 6 O 2 a... 80 100 Stress o (psi) xz. i Fig. 14. Normal Stress Distribution for a Simply-Supported Laminated Beam, T=z (2z/H+1) (x/L) 2 2 m. 1 6 4 x Classical Solution o Present Solution Load: Sinusoidal I F 0 100 200 300 400 Stress c (ps&) XX. 1 500...

Marcano, Victor Manuel

2012-06-07T23:59:59.000Z

469

State-to-state dynamics of molecular energy transfer  

SciTech Connect (OSTI)

The goal of this research program is to elucidate the elementary dynamical mechanisms of vibrational and rotational energy transfer between molecules, at a quantum-state resolved level of detail. Molecular beam techniques are used to isolate individual molecular collisions, and to control the kinetic energy of collision. Lasers are used both to prepare specific quantum states prior to collision by stimulated-emission pumping (SEP), and to measure the distribution of quantum states in the collision products by laser-induced fluorescence (LIF). The results are interpreted in terms of dynamical models, which may be cast in a classical, semiclassical or quantum mechanical framework, as appropriate.

Gentry, W.R.; Giese, C.F. [Univ. of Minnesota, Minneapolis (United States)

1993-12-01T23:59:59.000Z

470

I n s i t u thermal oxidation for surface cleaning and mask generation prior to selective area epitaxy  

Science Journals Connector (OSTI)

Dry thermal oxidation of GaAs and AlAs has been carried out in an organometallic chemical vapor deposition system. This i n s i t u process performed either before or after an epitaxialgrowth serves the purposes of surface cleaning and mask generation for selective area epitaxy of various III?V semiconductors.AlAsoxidized immediately after growth and patterned for the next regrowth provides better oxide?semiconductor interfaces and minimizes wafer handling. Pre?epitaxy oxidation at 435?°C on a patterned wafer with AlAs/GaAs areas resulted in a selective oxide mask. Since thermal oxides of GaAssublime at temperatures >600?°C a 700?°C pregrowth annealing thus thermally cleans the oxidizedGaAs areas while the oxides of AlAs remain as a mask for the following regrowth. Photoluminescence results indicate that high quality regrown interfaces have been obtained.

Stephen H. Jones; Kei May Lau

1988-01-01T23:59:59.000Z

471

Magnetic anisotropies in epitaxial Fe{sub 3}O{sub 4}/GaAs(100) patterned structures  

SciTech Connect (OSTI)

Previous studies on epitaxial Fe{sub 3}O{sub 4} rings in the context of spin-transfer torque effect have revealed complicated and undesirable domain structures, attributed to the intrinsic fourfold magnetocrystalline anisotropy in the ferrite. In this Letter, we report a viable solution to this problem, utilizing a 6-nm-thick epitaxial Fe{sub 3}O{sub 4} thin film on GaAs(100), where the fourfold magnetocrystalline anisotropy is negligible. We demonstrate that in the Fe{sub 3}O{sub 4} planar wires patterned from our thin film, such a unique magnetic anisotropy system has been preserved, and relatively simple magnetic domain configurations compared to those previous reports can be obtained.

Zhang, W., E-mail: xiaotur@gmail.com; Zhang, D.; Yuan, S. J.; Huang, Z. C.; Zhai, Y. [Department of Physics, Southeast University, Nanjing 211189 (China); Wong, P. K. J. [NanoElectronics Group, MESA Institute for Nanotechnology, University of Twente, P. O. Box 217, 7500 AE Enschede (Netherlands); Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 (Singapore); Wu, J. [Department of Physics, University of York, York YO10 5DD (United Kingdom); Xu, Y. B. [Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York, YO10 5DD (United Kingdom)

2014-10-15T23:59:59.000Z

472

High energy laser beam dump  

DOE Patents [OSTI]

The laser beam dump is positioned in a housing. An absorbing glass plate means is operatively connected to the housing. A heat sync means for extracting heat from the absorbing glass plate means is operatively connected to the housing and operatively connected to the absorbing glass plate means.

Halpin, John (Tracy, CA)

2004-09-14T23:59:59.000Z

473

Relativistic atomic beam spectroscopy II  

SciTech Connect (OSTI)

We are requesting support for a postdoctoral person to participate in H{sup -} studies at Los Alamos. In addition, we are requesting funding for a state-of-the-art YAG laser system that would allow us to obtain data at three times our present rate with improved beam quality.

NONE

1991-12-31T23:59:59.000Z

474

Anomalous thickness-dependent strain states and strain-tunable magnetization in Zn-doped ferrite epitaxial films  

SciTech Connect (OSTI)

A series of Zn{sub x}Fe{sub 3?x}O{sub 4} (ZFO, x?=?0.4) thin films were epitaxially deposited on single-crystal (001)-SrTiO{sub 3} (STO) substrates by radio frequency magnetron sputtering. The anomalous thickness-dependent strain states of ZFO films were found, i.e., a tensile in-plane strain exists in the thinner ZFO film and which monotonously turns into compressive in the thicker films. Considering the lattice constant of bulk ZFO is bigger than that of STO, this strain state cannot be explained in the conventional framework of lattice-mismatch-induced strain in the hetero-epitaxial system. This unusual phenomenon is proposed to be closely related to the Volmer-Weber film growth mode in the thinner films and incorporation of the interstitial atoms into the island's boundaries during subsequent epitaxial growth of the thicker films. The ZFO/STO epitaxial film is found in the nature of magnetic semiconductor by transport measurements. The in-plane magnetization of the ZFO/STO films is found to increase as the in-plane compressive strain develops, which is further proved in the (001)-ZFO/PMN-PT film where the film strain state can be in situ controlled with applied electric field. This compressive-strain-enhanced magnetization can be attributed to the strain-mediated electric-field-induced in-plane magnetic anisotropy field enhancement. The above results indicate that strain engineering on magnetic oxide semiconductor ZFO films is promising for novel oxide-electronic devices.

Yang, Y. J.; Bao, J.; Gao, C., E-mail: zlluo@ustc.edu.cn, E-mail: cgao@ustc.edu.cn [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230026 (China); CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Yang, M. M.; Luo, Z. L., E-mail: zlluo@ustc.edu.cn, E-mail: cgao@ustc.edu.cn; Hu, C. S.; Chen, X. C.; Pan, G. Q. [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230026 (China); Huang, H. L. [CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, S.; Wang, J. W.; Li, P. S.; Liu, Y.; Zhao, Y. G. [Department of Physics and State Key Laboratory of New Ceramics, Fine Processing, Tsinghua University, Beijing 100084 (China); Jiang, T.; Liu, Y. K.; Li, X. G. [Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science, Technology of China, Hefei, Anhui 230026 (China)

2014-05-07T23:59:59.000Z

475

Epitaxial growth of CdTe oriented thin films, infrared characterization and possible applications to photo-voltaic cells  

E-Print Network [OSTI]

573 Epitaxial growth of CdTe oriented thin films, infrared characterization and possible décembre 1979, accepté le 12 décembre 1979) Résumé. 2014 Des films minces orientés de CdTe, d de CdTe cubique dont la face (111), polie mécaniquement et décapée chimiquement, est préalablement

Paris-Sud XI, Université de

476

Simplified Procedure for Estimating Epitaxy of La2Zr2O7-Buffered NiW RABITS Using XRD  

SciTech Connect (OSTI)

Abstract A procedure is developed for assessing the epitaxy of La(2-x)Zr(2+x)O(7) (LZO) layers on NiW RABITS. Comparing XRD patterns (theta / 2-theta scans and 2D rocking curves) of LZO films of known thickness (ellipsometry or reflectometry measurements) with those of standard samples (100% epitaxial LZO film and an isotropic LZO pellet of known density), we estimate the epitaxial (EF), and polycrystalline (PF) fractions of LZO within the layer. The procedure was tested using MOD-LZO(100 nm)/NiW tape samples with varied from 3 to 90% (reproducibly prepared by varying the humidity of Ar-5%H2 gas during heat treatment). A qualitative agreement with RHEED and quantitative (within 10%) agreement with the EBSD results was shown. Correlation between EF and Jc in 600 nm thick YBCO layer deposited on MOD-LZO/NiW using thermal coevaporation enables us to impose the EF=80% margin on the quality of LZO layer for the particular conductor architecture.

Rikel, Mark O. [Nexans Superconductors; Isfort, Dirk [Nexans Superconductors; Klein, Marcel [Nexans Superconductors; Ehrenberg, Jurgen [Nexans Superconductors; Bock, Joachim [Nexans Superconductors; Specht, Eliot D [ORNL; Sun-Wagener, Ming [Fraunhofer-Institut fur Silicatforschung, Wurzburg; Weber, Oxana [Fraunhofer-Institut fur Silicatforschung, Wurzburg; Sporn, Dieter [Fraunhofer-Institut fur Silicatforschung, Wurzburg; Engel, Sebastian [Evico; de Haas, Oliver [Evico; Semerad, Robert [Theva Dunnschichttechnik, Germany; Schubert, Margitta [IFW Dresden; Holzapfel, Bernhard [IFW Dresden

2009-01-01T23:59:59.000Z

477

Electron Beam--21st Century Food Technology  

E-Print Network [OSTI]

This publication explains electron beam irradiation technology to consumers, industry professionals and government officials. Electron beam irradiation is a method of treating food and other products for pathogens that might jeopardize food safety....

Vestal, Andy

2003-03-07T23:59:59.000Z

478

Autogenerator of beams of charged particles  

DOE Patents [OSTI]

An autogenerating apparatus provides secondary intense relativistic current beam pulses in response to an injected beam pulse. One or more electromagnetic energy storage devices are provided in conjunction with gaps along a beam propagation path for the injected beam pulse. For injected beam pulses which are no longer than double the transit time of electromagnetic waves within the storage devices (which may be resonant cavities), distinct secondary beam pulses are generated by each of the energy storage devices. The beam propagation path, together with the one or more gaps provided therein, operates as a pulse forming transmission line cavity, in which the separate cavities associated with the gaps provide delays for electromagnetic waves generated at the gaps. After doubly traversing the cavity, the electromagnetic waves cause the gap to generate the secondary beam pulses, which are thus delayed by a time interval equal to the double transit time for the induced wave within the cavity.

Adler, R.J.; Mazarakis, M.G.; Miller, R.M.; Shope, S.L.; Smith, D.L.

1983-10-31T23:59:59.000Z

479