WorldWideScience

Sample records for ge 2541

  1. 7 CFR 29.2541 - Packing.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Packing. 29.2541 Section 29.2541 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2541 Packing. A lot of tobacco consisting...

  2. 45 CFR 2541.410 - Financial reporting.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Financial reporting. 2541.410 Section 2541.410... GOVERNMENTS Reports, Records, Retention and Enforcement § 2541.410 Financial reporting. (a) General. (1... time to time be authorized by OMB, for: (i) Submitting financial reports to Federal agencies; or...

  3. 45 CFR 2541.310 - Real property.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Real property. 2541.310 Section 2541.310 Public... Changes, Property and Subawards § 2541.310 Real property. (a) Title. Subject to the obligations and conditions set forth in this section, title to real property acquired under a grant or subgrant will...

  4. 45 CFR 2541.440 - Termination for convenience.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Termination for convenience. 2541.440 Section 2541.440 Public Welfare Regulations Relating to Public Welfare (Continued) CORPORATION FOR NATIONAL AND... LOCAL GOVERNMENTS Reports, Records, Retention and Enforcement § 2541.440 Termination for...

  5. 45 CFR 2541.300 - Changes.

    Science.gov (United States)

    2010-10-01

    .... (b) Relation to cost principles. The applicable cost principles (see § 2541.220) contain requirements... key persons in cases where specified in an application or a grant award. In research projects, a... by law) or otherwise obtaining the services of a third party to perform activities which are...

  6. 45 CFR 2541.200 - Standards for financial management systems.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Standards for financial management systems. 2541... STATE AND LOCAL GOVERNMENTS Post-Award Requirements § 2541.200 Standards for financial management... violation of the restrictions and prohibitions of applicable statutes. (b) The financial management systems...

  7. Removal of metal cyanides from aqueous solutions by suspended and immobilized cells of rhizopus oryzae (MTCC 2541)

    Energy Technology Data Exchange (ETDEWEB)

    Roshan Dash, Rajesh; Kumar, Arvind [Department of Civil Engineering, IIT Roorkee, Roorkee, Uttarakhand (India); Balomajumder, Chandrajit [Department of Chemical Engineering, IIT Roorkee, Roorkee, Uttarakhand (India)

    2009-02-15

    This paper presents a study on biodegradation and simultaneous adsorption and biodegradation (SAB) of zinc and iron cyanides by Rhizopus oryzae (MTCC 2541), with a brief process review. Granular activated carbon was used for the immobilization of Rhizopus oryzae (MTCC 2541) for the SAB study. pH and temperature were optimized at an initial cyanide concentration of 100 mg/L for biodegradation and SAB. The microbes adapted to grow at maximum cyanide concentration were harvested and their ability to degrade cyanide was measured in both biodegradation and SAB. The removal efficiency of the SAB process was found to be better as compared to the biodegradation process. In the case of biodegradation, removal was found up to a maximum cyanide concentration of 250 mg CN{sup -}/L for zinc cyanide and 200 mg CN{sup -}/L for iron cyanide, whereas in the case of SAB, about 50% removal of cyanide at 400 mg CN{sup -}/L zinc cyanide and 300 mg CN{sup -}/L iron cyanide was possible. It was found that the SAB process is more effective than biodegradation. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  8. Pseudomorphic GeSn/Ge (001) heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Tonkikh, A. A., E-mail: tonkikh@mpi-halle.de [Max Planck Institute of Microstructure Physics (Germany); Talalaev, V. G. [Martin Luther University Halle-Wittenberg, ZIK SiLi-nano (Germany); Werner, P. [Max Planck Institute of Microstructure Physics (Germany)

    2013-11-15

    The synthesis of pseudomorphic GeSn heterostructures on a Ge (001) substrate by molecular-beam epitaxy is described. Investigations by transmission electron microscopy show that the GeSn layers are defect free and possess cubic diamondlike structure. Photoluminescence spectroscopy reveals interband radiative recombination in the GeSn quantum wells, which is identified as indirect transitions between the subbands of heavy electrons and heavy holes. On the basis of experimental data and modeling of the band structure of pseudomorphic GeSn compounds, the lower boundary of the bowing parameter for the indirect band gap is estimated as b{sub L} {>=} 1.47 eV.

  9. GeSn/Ge multiquantum well photodetectors on Si substrates.

    Science.gov (United States)

    Oehme, M; Widmann, D; Kostecki, K; Zaumseil, P; Schwartz, B; Gollhofer, M; Koerner, R; Bechler, S; Kittler, M; Kasper, E; Schulze, J

    2014-08-15

    Vertical incidence GeSn/Ge multiquantum well (MQW) pin photodetectors on Si substrates were fabricated with a Sn concentration of 7%. The epitaxial structure was grown with a special low temperature molecular beam epitaxy process. The Ge barrier in the GeSn/Ge MQW was kept constant at 10 nm. The well width was varied between 6 and 12 nm. The GeSn/Ge MQW structures were grown pseudomorphically with the in-plane lattice constant of the Ge virtual substrate. The absorption edge shifts to longer wavelengths with thicker QWs in agreement with expectations from smaller quantization energies for the thicker QWs.

  10. Photoluminescence and electroluminescence from Ge/strained GeSn/Ge quantum wells

    Science.gov (United States)

    Lin, Chung-Yi; Huang, Chih-Hsiung; Huang, Shih-Hsien; Chang, Chih-Chiang; Liu, C. W.; Huang, Yi-Chiau; Chung, Hua; Chang, Chorng-Ping

    2016-08-01

    Ge/strained GeSn/Ge quantum wells are grown on a 300 mm Si substrate by chemical vapor deposition. The direct bandgap emission from strained GeSn is observed in the photoluminescence spectra and is enhanced by Al2O3/SiO2 passivation due to the field effect. The electroluminescence of the direct bandgap emission of strained GeSn is also observed from the Ni/Al2O3/GeSn metal-insulator-semiconductor tunneling diodes. Electroluminescence is a good indicator of GeSn material quality, since defects in GeSn layers degrade the electroluminescence intensity significantly. At the accumulation bias, the holes in the Ni gate electrode tunnel to the strained n-type GeSn layer through the ultrathin Al2O3 and recombine radiatively with electrons. The emission wavelength of photoluminescence and electroluminescence can be tuned by the Sn content.

  11. Metastable Ge nanocrystalline in SiGe matrix for photodiode

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Yao-Tsung; Su, Chien-Hao [Department of Chemical and Materials Engineering, National Central University, Taoyuan City 320, Taiwan (China); Chang, Jenq-Yang [Department of Optics and Photonics, National Central University, Taoyuan City 320, Taiwan (China); Cheng, Shao-Liang; Lin, Po-Chen [Department of Chemical and Materials Engineering, National Central University, Taoyuan City 320, Taiwan (China); Wu, Albert T., E-mail: atwu@ncu.edu.tw [Department of Chemical and Materials Engineering, National Central University, Taoyuan City 320, Taiwan (China)

    2015-09-15

    Highlights: • Amorphous Si{sub 1−x}Ge{sub x} films were prepared by co-sputtering by using rapid thermal annealing to form nanocrystal films. • Si–Ge alloy does not form total solid solution that is shown in phase diagram. • HRTEM images indicated that Ge atoms segregated and formed Ge clusters that are embedded in the amorphous Si–Ge matrix. • Ge segregation permitted high mobility; the grain size increased and the resistivity decreased with higher Ge content. • The rectifying property became stronger with the Ge fraction in the Si{sub 1−x}Ge{sub x} diodes. Si{sub 1−x}Ge{sub x} diodes are used as photodetectors, which provide a greater output current under illumination. - Abstract: Amorphous Si{sub 1−x}Ge{sub x} films were prepared by co-sputtering on an oxidized Si wafer, followed by rapid thermal annealing to form nanocrystal films. The formation of Ge nanocrystals was not at thermodynamic equilibrium formed in the amorphous Si{sub 1−x}Ge{sub x} matrix. High-resolution transmission electron microscopy was used to characterize the increase in the size of the grains in the Ge nanocrystals as the Ge content increased. The Ge nanocrystals have a greater absorption in the near-infrared region and higher carrier mobility than SiGe crystals, and the variation in their grain sizes can be used to tune the bandgap. This characteristic was exploited herein to fabricate n-Si{sub 1−x}Ge{sub x}/p-Si{sub 1−x}Ge{sub x} p–n diodes on insulating substrates, which were then examined by analyzing their current–voltage characteristics. The rectifying property became stronger as the fraction of Ge in the Si{sub 1−x}Ge{sub x} films increased. The Si{sub 1−x}Ge{sub x} diodes are utilized as photodetectors that have a large output current under illumination. This paper elucidates the correlations between the structural, optical and electrical properties and the p–n junction performance of the film.

  12. Germanene termination of Ge2Pt crystals on Ge(110)

    NARCIS (Netherlands)

    Bampoulis, Pantelis; Zhang, Lijie; Safaei, A.; van Gastel, Raoul; Poelsema, Bene; Zandvliet, Henricus J.W.

    2014-01-01

    We have investigated the growth of Pt on Ge(1 1 0) using scanning tunneling microscopy and spectroscopy. The deposition of several monolayers of Pt on Ge(1 1 0) followed by annealing at 1100 K results in the formation of 3D metallic Pt-Ge nanocrystals. The outermost layer of these crystals exhibits

  13. Synthesis of Epitaxial Films Based on Ge-Si-Sn Materials with Ge/GeSn, Ge/GeSiSn, and GeSn/GeSiSn Heterojunctions

    Science.gov (United States)

    Timofeev, V. A.; Kokhanenko, A. P.; Nikiforov, A. I.; Mashanov, V. I.; Tuktamyshev, A. R.; Loshkarev, I. D.

    2015-11-01

    Results of investigations into the synthesis of heterostructures based on Ge-Si-Sn materials by the method of low-temperature molecular beam epitaxy are presented. The formation of epitaxial films during structure growth has been controlled by the reflection high-energy electron diffraction method. Films with Ge/GeSn, Ge/GeSiSn, and GeSn/GeSiSn heterojunctions are grown with Sn content changing from 2 to 10 % at temperatures in the interval 150-350°C. The stressed state, the composition, and the lattice parameter are studied by the x-ray diffraction method using Omega-scan curves and reciprocal space maps. A tensile strain in the Ge film during Ge/Ge0.9Sn0.1/Si structure growth has reached 0.86%.

  14. Characteristics of Sn segregation in Ge/GeSn heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.; Chang, C.; Chen, T. P.; Cheng, H. H., E-mail: hhcheng@ntu.edu.tw [Center for Condensed Matter Sciences and Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Shi, Z. W.; Chen, H. [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-10-13

    We report an investigation of Sn segregation in Ge/GeSn heterostructures occurred during the growth by molecular beam epitaxy. The measured Sn profile in the Ge layer shows that: (a) the Sn concentration decreases rapidly near the Ge/GeSn interface, and (b) when moving away from the interface, the Sn concentration reduced with a much slower rate. The 1/e decay lengths of the present system are much longer than those of the conventional group IV system of Ge segregation in the Si overlayer because of the smaller kinetic potential as modeled by a self-limited two-state exchange scheme. The demonstration of the Sn segregation shows the material characteristics of the heterostructure, which are needed for the investigation of its optical properties.

  15. Phonons in Ge/Si superlattices with Ge quantum dots

    CERN Document Server

    Milekhin, A G; Pchelyakov, O P; Schulze, S; Zahn, D R T

    2001-01-01

    Ge/Si superlattices with Ge quantum dots obtained by means of molecular-beam epitaxy were investigated by means of light Raman scattering under resonance conditions. These structures are shown to have oscillation properties of both two-dimensional and zero-dimensional objects. Within spectrum low-frequency range one observes twisted acoustic phonons (up to 15 order) typical for planar superlattices. Lines of acoustic phonons are overlapped with a wide band of continuous emission. Analysis of frequencies of Ge and Ge-Si optical phonons shows that Ge quantum dots are pseudoamorphous ones and mixing of Ge and Si atoms is a negligible one. One detected low-frequency shift of longitudinal optical phonons at laser excitation energy increase (2.54-2.71 eV)

  16. A global Ge isotope budget

    Science.gov (United States)

    Baronas, J. Jotautas; Hammond, Douglas E.; McManus, James; Wheat, C. Geoffrey; Siebert, Christopher

    2017-04-01

    We present measurements of Ge isotope composition and ancillary data for samples of river water, low- and high-temperature hydrothermal fluids, and seawater. The dissolved δ74Ge composition of analyzed rivers ranges from 2.0 to 5.6‰, which is significantly heavier than previously determined values for silicate rocks (δ74Ge = 0.4-0.7‰, Escoube et al., Geostand. Geoanal. Res., 36(2), 2012) from which dissolved Ge is primarily derived. An observed negative correlation between riverine Ge/Si and δ74Ge signatures suggests that the primary δ74Ge fractionation mechanism during rock weathering is the preferential incorporation of light isotopes into secondary weathering products. High temperature (>150 °C) hydrothermal fluids analyzed in this study have δ74Ge of 0.7-1.6‰, most likely fractionated during fluid equilibration with quartz in the reaction zone. Low temperature (25-63 °C) hydrothermal fluids are heavier (δ74Ge between 2.9‰ and 4.1‰) and most likely fractionated during Ge precipitation with hydrothermal clays. Seawater from the open ocean has a δ74Gesw value of 3.2 ± 0.4‰, and is indistinguishable among the different ocean basins at the current level of precision. This value should be regulated over time by the isotopic balance of Ge sources and sinks, and a new compilation of these fluxes is presented, along with their estimated isotopic compositions. Assuming steady-state, non-opal Ge sequestration during sediment authigenesis likely involves isotopic fractionation Δ74Gesolid-solution that is -0.6 ± 1.8‰.

  17. Ge/SiGe superlattices for nanostructured thermoelectric modules

    Energy Technology Data Exchange (ETDEWEB)

    Chrastina, D., E-mail: daniel@chrastina.net [L-NESS Politecnico di Milano, Polo di Como, via Anzani 42, 22100 Como (Italy); Cecchi, S. [L-NESS Politecnico di Milano, Polo di Como, via Anzani 42, 22100 Como (Italy); Hague, J.P. [Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA (United Kingdom); Frigerio, J. [L-NESS Politecnico di Milano, Polo di Como, via Anzani 42, 22100 Como (Italy); Samarelli, A.; Ferre–Llin, L.; Paul, D.J. [School of Engineering, University of Glasgow, Oakfield Avenue, Glasgow, G12 8LT (United Kingdom); Müller, E. [Electron Microscopy ETH Zurich (EMEZ), ETH-Zürich, CH-8093 (Switzerland); Etzelstorfer, T.; Stangl, J. [Institut für Halbleiter und Festkörperphysik, Universität Linz, A-4040 Linz (Austria); Isella, G. [L-NESS Politecnico di Milano, Polo di Como, via Anzani 42, 22100 Como (Italy)

    2013-09-30

    Thermoelectrics are presently used in a number of applications for both turning heat into electricity and also for using electricity to produce cooling. Mature Si/SiGe and Ge/SiGe heteroepitaxial growth technology would allow highly efficient thermoelectric materials to be engineered, which would be compatible and integrable with complementary metal oxide silicon micropower circuits used in autonomous systems. A high thermoelectric figure of merit requires that electrical conductivity be maintained while thermal conductivity is reduced; thermoelectric figures of merit can be improved with respect to bulk thermoelectric materials by fabricating low-dimensional structures which enhance the density of states near the Fermi level and through phonon scattering at heterointerfaces. We have grown and characterized Ge-rich Ge/SiGe/Si superlattices for nanofabricated thermoelectric generators. Low-energy plasma-enhanced chemical vapor deposition has been used to obtain nanoscale-heterostructured material which is several microns thick. Crystal quality and strain control have been investigated by means of high resolution X-ray diffraction. High-resolution transmission electron microscopy images confirm the material and interface quality. Electrical conductivity has been characterized by the mobility spectrum technique. - Highlights: ► High-quality Ge/SiGe multiple quantum wells for thermoelectric applications ► Mobility spectra of systems featuring a large number of parallel conduction channels ► Competitive thermoelectric properties measured in single devices.

  18. Isospin structure in 68Ge

    Institute of Scientific and Technical Information of China (English)

    BAI Hong-Bo; DONG Hong-Fei; ZHANG Jin-Fu; LU Li-Jun; CAO Wan-Cang; LI Xiao-Wei; WANg Yin

    2009-01-01

    The interacting boson model-3(IBM-3) has been used to study the low-energy level structure and electromagnetic transitions of 68Ge nucleus. The main components of the wave function for some states are also analyzed respectively. The theoretical calculations are in agreement with experimental data, and the 68Ge is in transition from U(5) to SU(3).

  19. 12 GeV Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    None

    2017-01-01

    To expand the opportunity for discovery, Jefferson Lab is upgrading its facility by doubling the maximum energy of CEBAF's electron beam from 6 billion electron volts (GeV) to 12 billion electron volts (GeV), constructing a new experimental hall and upgrading its three existing experimental halls.

  20. Monolithically integrated Ge CMOS laser

    Science.gov (United States)

    Camacho-Aguilera, Rodolfo

    2014-02-01

    Ge-on-Si devices are explored for photonic integration. Through the development of better growth techniques, monolithic integration, laser design and prototypes, it was possible to probe Ge light emitters with emphasis on lasers. Preliminary worked shows thermal photonic behavior capable of enhancing lamination at high temperatures. Increase luminescence is observed up to 120°C from L-band contribution. Higher temperatures show contribution from Δ -band. The increase carrier thermal contribution suggests high temperature applications for Ge light emitters. A Ge electrically pumped laser was probed under 0.2% biaxial strain and doping concentration ~4.5×1019cm-3 n-type. Ge pnn lasers exhibit a gain >1000cm-1 with 8mW power output, presenting a spectrum range of over 200nm, making Ge the ideal candidate for Si photonics. Large temperatures fluctuations and process limit the present device. Theoretically a gain of >4000cm- gain is possible with a threshold of as low as 1kA/cm2. Improvements in Ge work

  1. Ge-on-Si optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jifeng, E-mail: Jifeng.Liu@Dartmouth.edu [Thayer School of Engineering, Dartmouth College, Hanover, NH 03755 (United States); Camacho-Aguilera, Rodolfo; Bessette, Jonathan T.; Sun, Xiaochen [Microphotonics Center, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Wang Xiaoxin [Thayer School of Engineering, Dartmouth College, Hanover, NH 03755 (United States); Cai Yan; Kimerling, Lionel C.; Michel, Jurgen [Microphotonics Center, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2012-02-01

    Electronic-photonic synergy has become an increasingly clear solution to enhance the bandwidth and improve the energy efficiency of information systems. Monolithic integration of optoelectronic devices is the ideal solution for large-scale electronic-photonic synergy. Due to its pseudo-direct gap behavior in optoelectronic properties and compatibility with Si electronics, epitaxial Ge-on-Si has become an attractive solution for monolithic optoelectronics. In this paper we will review recent progress in Ge-on-Si optoelectronics, including photodetectors, electroabsorption modulators, and lasers. The performance of these devices has been enhanced by band-engineering such as tensile strain and n-type doping, which transforms Ge towards a direct gap material. Selective growth reduces defect density and facilitates monolithic integration at the same time. Ge-on-Si photodetectors have approached or exceeded the performance of their III-V counterparts, with bandwidth-efficiency product > 30 GHz for p-i-n photodiodes and bandwidth-gain product > 340 GHz for avalanche photodiodes. Enhanced Franz-Keldysh effect in tensile-strained Ge offers ultralow energy photonic modulation with < 30 fJ/bit energy consumption and > 100 GHz intrinsic bandwidth. Room temperature optically-pumped lasing as well as electroluminescence has also been achieved from the direct gap transition of band-engineered Ge-on-Si waveguides. These results indicate that band-engineered Ge-on-Si is promising to achieve monolithic active optoelectronic devices on a Si platform.

  2. 77 FR 2541 - Board Meeting

    Science.gov (United States)

    2012-01-18

    ... meetings, persons requiring assistance should make arrangements in advance. The matters to be considered at... Investment Portfolio Review of Insurance Premium Rates Overview of Communications Crisis Plan with...

  3. <300> GeV team

    CERN Multimedia

    1971-01-01

    The 300 GeV team had been assembled. In the photograph are Hans Horisberger, Clemens Zettler, Roy Billinge, Norman Blackburne, John Adams, Hans-Otto Wuster, Lars Persson, Bas de Raad, Hans Goebel, Simon Van der Meer.

  4. Epi-cleaning of Ge/GeSn heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Di Gaspare, L.; Sabbagh, D.; De Seta, M.; Sodo, A. [Dipartimento di Scienze, Università Roma Tre, Viale Marconi 446, 00146 Rome (Italy); Wirths, S.; Buca, D. [Peter Grünberg Institute 9 and JARA-Fundamentals of Future Information Technologies, Forschungszentrum Juelich, Juelich 52425 (Germany); Zaumseil, P. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Schroeder, T. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); BTU Cottbus, Konrad-Zuse Str. 1, 03046 Cottbus (Germany); Capellini, G., E-mail: capellini@ihp-microelectronics.com [Dipartimento di Scienze, Università Roma Tre, Viale Marconi 446, 00146 Rome (Italy); IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany)

    2015-01-28

    We demonstrate a very-low temperature cleaning technique based on atomic hydrogen irradiation for highly (1%) tensile strained Ge epilayers grown on metastable, partially strain relaxed GeSn buffer layers. Atomic hydrogen is obtained by catalytic cracking of hydrogen gas on a hot tungsten filament in an ultra-high vacuum chamber. X-ray photoemission spectroscopy, reflection high energy electron spectroscopy, atomic force microscopy, secondary ion mass spectroscopy, and micro-Raman showed that an O- and C-free Ge surface was achieved, while maintaining the same roughness and strain condition of the as-deposited sample and without any Sn segregation, at a process temperature in the 100–300 °C range.

  5. V-Ge-Cu system

    Energy Technology Data Exchange (ETDEWEB)

    Savitskij, E.M.; Efimov, Yu.V.; Bodak, O.I.; Kharchenko, O.I.; Shomova, N.A.; Frolova, T.M.

    By the methods of microscopic, X-ray phase analyses, X-ray spectral microanalysis as well as by measurement of Tsub(C) and phase lattice parameters the structure of the vanadium-region of the V-Ge ternary system (up to 40 at.%) - Cu(up to 90 at.%) is studied and isothermal cross section at 800 deg C is plotted. In the studied region solid solutions on the base of vanadium, copper and V/sub 3/Ge and V/sub 5/Ge/sub 3/ compounds are in phase equilibria. The solid solution on the vanadium base in ternary alloys practically does not possess superconductivity at the temperature over 4.2 K. Tsub(C) of V/sub 3/Ge saturated with copper decreases up to 5.3-5.6 K depending on treatment conditions and alloys composition. The superspeed quenching from molten state and the consequent low-temperature tempering of ternary alloys can increase V/sub 3/Ge Tsub(C) up to 6-6.7 K.

  6. Band calculation of lonsdaleite Ge

    Science.gov (United States)

    Chen, Pin-Shiang; Fan, Sheng-Ting; Lan, Huang-Siang; Liu, Chee Wee

    2017-01-01

    The band structure of Ge in the lonsdaleite phase is calculated using first principles. Lonsdaleite Ge has a direct band gap at the Γ point. For the conduction band, the Γ valley is anisotropic with the low transverse effective mass on the hexagonal plane and the large longitudinal effective mass along the c axis. For the valence band, both heavy-hole and light-hole effective masses are anisotropic at the Γ point. The in-plane electron effective mass also becomes anisotropic under uniaxial tensile strain. The strain response of the heavy-hole mass is opposite to the light hole.

  7. Demonstration of a Ge/GeSn/Ge quantum-well microdisk resonator on silicon: enabling high-quality Ge(Sn) materials for micro- and nanophotonics.

    Science.gov (United States)

    Chen, Robert; Gupta, Suyog; Huang, Yi-Chiau; Huo, Yijie; Rudy, Charles W; Sanchez, Errol; Kim, Yihwan; Kamins, Theodore I; Saraswat, Krishna C; Harris, James S

    2014-01-08

    We theoretically study and experimentally demonstrate a pseudomorphic Ge/Ge0.92Sn0.08/Ge quantum-well microdisk resonator on Ge/Si (001) as a route toward a compact GeSn-based laser on silicon. The structure theoretically exhibits many electronic and optical advantages in laser design, and microdisk resonators using these structures can be precisely fabricated away from highly defective regions in the Ge buffer using a novel etch-stop process. Photoluminescence measurements on 2.7 μm diameter microdisks reveal sharp whispering-gallery-mode resonances (Q > 340) with strong luminescence.

  8. Neutron transmutation doped Ge bolometers

    Science.gov (United States)

    Haller, E. E.; Kreysa, E.; Palaio, N. P.; Richards, P. L.; Rodder, M.

    1983-01-01

    Some conclusions reached are as follow. Neutron Transmutation Doping (NTD) of high quality Ge single crystals provides perfect control of doping concentration and uniformity. The resistivity can be tailored to any given bolometer operating temperature down to 0.1 K and probably lower. The excellent uniformity is advantaged for detector array development.

  9. Superconductivity in novel Ge-based skutterudites: {Sr,Ba}pt4Ge12.

    Science.gov (United States)

    Bauer, E; Grytsiv, A; Chen, Xing-Qiu; Melnychenko-Koblyuk, N; Hilscher, G; Kaldarar, H; Michor, H; Royanian, E; Giester, G; Rotter, M; Podloucky, R; Rogl, P

    2007-11-23

    Combining experiments and ab initio models we report on SrPt4Ge12 and BaPt4Ge12 as members of a novel class of superconducting skutterudites, where Sr or Ba atoms stabilize a framework entirely formed by Ge atoms. Below T(c)=5.35 and 5.10 K for BaPt4Ge12 and SrPt4Ge12, respectively, electron-phonon coupled superconductivity emerges, ascribed to intrinsic features of the Pt-Ge framework, where Ge-p states dominate the electronic structure at the Fermi energy.

  10. Evolution of Ge and SiGe Quantum Dots under Excimer Laser Annealing

    Institute of Scientific and Technical Information of China (English)

    HAN Gen-Quan; ZENG Yu-Gang; YU Jin-Zhong; CHENG Bu-Wen; YANG Hai-Tao

    2008-01-01

    We present different relaxation mechanisms of Ge and SiGe quantum dots under excimer laser annealing.Inyestigation of the coarsening and relaxation of the dots showS that the strain in Ge dots on Ge films is relaxed by dislocation since there is no interface between the Ge dots and the Ge layer,while the SiGe dots on Si0.77 Ge0.23film relax by lattice distortion to coherent dots which results from the obvious interface between the SiGe dots and the Si0.77Ge0.23 film.The results are suggested and sustained by Vanderbilt and Wickham's theory,and also demonstrate that no bulk diffusion Occurs during the excimer laser annealing.

  11. Understanding and engineering of NiGe/Ge junction formed by phosphorus ion implantation after germanidation

    Energy Technology Data Exchange (ETDEWEB)

    Oka, Hiroshi, E-mail: oka@asf.mls.eng.osaka-u.ac.jp; Minoura, Yuya; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji [Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2014-08-11

    Modulation of the effective electron Schottky barrier height (eSBH) of NiGe/Ge contacts induced by phosphorus ion implantation after germanide formation was investigated by considering local inhomogeneity in the eSBH. Systematic studies of NiGe/Ge contact devices having various germanide thicknesses and ion implantation areas indicated the threshold dopant concentration at the NiGe/Ge interface required for eSBH modulation and negligible dopant diffusion even at NiGe/Ge interface during drive-in annealing, leading to variation in the eSBH between the bottom and sidewall portions of the NiGe regions. Consequently, this method makes it possible to design source/drain contacts with low-resistivity Ohmic and ideal rectifying characteristics for future Ge-based transistors.

  12. Germanium-tin interdiffusion in strained Ge/GeSn multiple-quantum-well structure

    Science.gov (United States)

    Wang, Wei; Dong, Yuan; Zhou, Qian; Tok, Eng Soon; Yeo, Yee-Chia

    2016-06-01

    The thermal stability and germanium-tin (Ge-Sn) interdiffusion properties were studied in epitaxial Ge/GeSn multiple-quantum-well (MQW) structure. No obvious interdiffusion was observed for annealing temperatures of 300 °C or below, while observable interdiffusion occurred for annealing temperatures of 380 °C and above. High-resolution x-ray diffraction was used to obtain the interdiffusion coefficient by analyzing the decrease rate of Ge/GeSn periodic satellite peaks. The interdiffusion coefficient is much higher, and the activation enthalpy of 1.21 eV is substantially lower in Ge/GeSn MQW structure than that previously reported in silicon-germanium (Si-Ge) systems. When the annealing temperature is increased to above 500 °C, Ge-Sn interdiffusion becomes severe. Some small pits appear on the surface, which should be related to Sn out-diffusion to the Ge cap layer, followed by Sn desorption from the top surface. This work provides insights into the Ge-Sn interdiffusion and Sn segregation behaviors in Ge/GeSn MQW structure, and the thermal budget that may be used for fabrication of devices comprising Ge/GeSn heterostructures.

  13. SPEIR: A Ge Compton Camera

    Energy Technology Data Exchange (ETDEWEB)

    Mihailescu, L; Vetter, K M; Burks, M T; Hull, E L; Craig, W W

    2004-02-11

    The SPEctroscopic Imager for {gamma}-Rays (SPEIR) is a new concept of a compact {gamma}-ray imaging system of high efficiency and spectroscopic resolution with a 4-{pi} field-of-view. The system behind this concept employs double-sided segmented planar Ge detectors accompanied by the use of list-mode photon reconstruction methods to create a sensitive, compact Compton scatter camera.

  14. The effects of strain on indirect absorption in Ge/SiGe quantum wells

    Science.gov (United States)

    Lever, L.; Ikonić, Z.; Kelsall, R. W.

    2012-06-01

    We calculate the conduction band electron scattering rates from the Γ-valley into the indirect valleys in germanium, and use this to determine the strength of the indirect absorption in Ge/SiGe quantum well heterostructures. This is done as a function of the in-plane compressive strain in the Ge quantum wells, which results from pseudomorphic growth on a SiGe virtual substrate. This compressive strain results in the Δ valleys becoming available as destination states for scattering, which leads to a reduction in the Γ-valley lifetime. We calculate the indirect absorption and lifetime broadening of excitonic peaks, and show that indirect absorption decreases as the Ge fraction in the virtual substrate increases. We conclude that the Ge fraction of the SiGe virtual substrate should be approximately 95% or larger for optimum electroabsorption performance of Ge/SiGe quantum wells.

  15. Segregation of Ge in B and Ge codoped Czochralski-Si crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Arivanandhan, Mukannan, E-mail: rmarivu@ipc.shizuoka.ac.jp [Department of Electronics and Materials Science, Graduate School of Engineering, Shizuoka University, Johoku 3-5-1, Naka-Ku, Hamamatsu 432-8011 (Japan); Research Institute of Electronics, Shizuoka University, Johoku 3-5-1, Naka-Ku, Hamamatsu 432-8011 (Japan); Gotoh, Raira; Fujiwara, Kozo; Uda, Satoshi [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Hayakawa, Yasuhiro [Department of Electronics and Materials Science, Graduate School of Engineering, Shizuoka University, Johoku 3-5-1, Naka-Ku, Hamamatsu 432-8011 (Japan); Research Institute of Electronics, Shizuoka University, Johoku 3-5-1, Naka-Ku, Hamamatsu 432-8011 (Japan)

    2015-08-05

    Highlights: • Effective segregation of Ge in B and Ge codoped Czochralski-Si crystal growth was analyzed. • The equilibrium segregation coefficient of Ge was calculated. • The experimentally results were analytically analyzed using partitioning theory. - Abstract: The segregation of Ge in B and Ge codoped Czochralski (CZ)-Si crystal growth was investigated. The concentration of Ge in heavily Ge codoped CZ-Si was measured by electron probe micro analysis (EPMA) and X-ray fluorescence spectroscopy. The effective segregation coefficient of Ge (k{sub eff}) was calculated by fitting the EPMA data to the normal freezing equation, and by taking the logarithmic ratio of the Ge concentrations at the seed and tail of the ingots (top to bottom approach). The k{sub eff} of Ge increased from 0.30 to 0.55, when the initial Ge concentration in the Si melt (C{sub L(o)}{sup Ge}) was increased from 3 × 10{sup 19} to 3 × 10{sup 21} cm{sup −3}. To avoid cellular growth, the crystal pulling rate was decreased for heavily Ge codoped crystal growth (C{sub L(o)}{sup Ge} > 3 × 10{sup 20} cm{sup −3}). The equilibrium segregation coefficient (k{sub 0}) of Ge was calculated by partitioning theory, and was smaller than the experimentally estimated k{sub eff}. The variation of k{sub eff} from k{sub 0} was discussed based on Ge clustering in the heavily Ge codoped crystal, which led to changes in the bonding and strain energies caused by the incorporation of Ge into Si.

  16. GeSn/Ge heterostructure short-wave infrared photodetectors on silicon.

    Science.gov (United States)

    Gassenq, A; Gencarelli, F; Van Campenhout, J; Shimura, Y; Loo, R; Narcy, G; Vincent, B; Roelkens, G

    2012-12-03

    A surface-illuminated photoconductive detector based on Ge0.91Sn0.09 quantum wells with Ge barriers grown on a silicon substrate is demonstrated. Photodetection up to 2.2µm is achieved with a responsivity of 0.1 A/W for 5V bias. The spectral absorption characteristics are analyzed as a function of the GeSn/Ge heterostructure parameters. This work demonstrates that GeSn/Ge heterostructures can be used to developed SOI waveguide integrated photodetectors for short-wave infrared applications.

  17. Ge nanobelts with high compressive strain fabricated by secondary oxidation of self-assembly SiGe rings

    DEFF Research Database (Denmark)

    Lu, Weifang; Li, Cheng; Lin, Guangyang

    2015-01-01

    Curled Ge nanobelts were fabricated by secondary oxidation of self-assembly SiGe rings, which were exfoliated from the SiGe stripes on the insulator. The Ge-rich SiGe stripes on insulator were formed by hololithography and modified Ge condensation processes of Si0.82Ge0.18 on SOI substrate. Ge na...... nanobelts, which extrudes to Ge nanobelts in radial and tangent directions during the cooling process. This technique is promising for application in high-mobility Ge nano-scale transistors...

  18. Effect of Ge Content on the Formation of Ge Nanoclusters in Magnetron-Sputtered GeZrOx-Based Structures.

    Science.gov (United States)

    Khomenkova, L; Lehninger, D; Kondratenko, O; Ponomaryov, S; Gudymenko, O; Tsybrii, Z; Yukhymchuk, V; Kladko, V; von Borany, J; Heitmann, J

    2017-12-01

    Ge-rich ZrO2 films, fabricated by confocal RF magnetron sputtering of pure Ge and ZrO2 targets in Ar plasma, were studied by multi-angle laser ellipsometry, Raman scattering, Auger electron spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction for varied deposition conditions and annealing treatments. It was found that as-deposited films are homogeneous for all Ge contents, thermal treatment stimulated a phase separation and a formation of crystalline Ge and ZrO2. The "start point" of this process is in the range of 640-700 °C depending on the Ge content. The higher the Ge content, the lower is the temperature necessary for phase separation, nucleation of Ge nanoclusters, and crystallization. Along with this, the crystallization temperature of the tetragonal ZrO2 exceeds that of the Ge phase, which results in the formation of Ge crystallites in an amorphous ZrO2 matrix. The mechanism of phase separation is discussed in detail.

  19. A study on NiGe-contacted Ge n+/p Ge shallow junction prepared by dopant segregation technique

    Science.gov (United States)

    Tsui, Bing-Yue; Shih, Jhe-Ju; Lin, Han-Chi; Lin, Chiung-Yuan

    2015-05-01

    In this work, the effect of dopant segregation on the NiGe/n-Ge contact is studied by experiments and first-principles calculations. Both Al-contacted and NiGe-contacted n+/p junctions were fabricated. Phosphorus and arsenic ions were Implanted Before Germanide (IBG) formation or Implanted After Germanide (IAG) formation. The NiGe-contacted junction always exhibit higher forward current than the Al-contacted junction due to dopant segregation. First principles calculations predict that phosphorus atoms tend to segregate on both NiGe side and Ge side while arsenic atoms tend to segregate at Ge side. Since phosphorus has higher activation level and lower diffusion coefficient than arsenic, we propose a phosphorus IBG + arsenic IAG process. Shallow n+/p junction with junction depth 90 nm below the NiGe/Ge interface is achieved. The lowest and average contact resistivity is 2 × 10-6 Ω cm2 and 6.7 × 10-6 Ω cm2, respectively. Methods which can further reduce the junction depth and contact resistivity are suggested.

  20. Mid- to long-wavelength infrared plasmonic-photonics using heavily doped n-Ge/Ge and n-GeSn/GeSn heterostructures.

    Science.gov (United States)

    Soref, Richard; Hendrickson, Joshua; Cleary, Justin W

    2012-02-13

    Heavily doped n-type Ge and GeSn are investigated as plasmonic conductors for integration with undoped dielectrics of Si, SiGe, Ge, and GeSn in order to create a foundry-based group IV plasmonics technology. N-type Ge1-xSnx with compositions of 0 ≤ x ≤ 0.115 are investigated utilizing effective-mass theory and Drude considerations. The plasma wavelengths, relaxation times, and complex permittivities are determined as functions of the free carrier concentration over the range of 10(10) to 10(21) cm-3. Basic plasmonic properties such as propagation loss and mode height are calculated and example numerical simulations are shown of a dielectric-conductor-dielectric ribbon waveguide structure are shown. Practical operation in the 2 to 20 μm wavelength range is predicted.

  1. Ge photocapacitive MIS infrared detectors

    Science.gov (United States)

    Binari, S. C.; Miller, W. E.; Tsuo, Y. H.; Miller, W. E.

    1979-01-01

    An undoped Ge photocapacitive detector is reported which has peak normalized detectivities at wavelengh 1.4 microns and chopping frequencies 13-1000 Hz of 9 x 10 to the 12th, 4 x 10 to the 9th cm Hz to the 1/2th/W operating respectively at temperatures 77, 195, and 295 K. The observed temperature, spectral, and frequency response of the signal and noise are explained in terms of the measured space charge and interface state properties of the device.

  2. Simulation of GeSn/Ge tunneling field-effect transistors for complementary logic applications

    Science.gov (United States)

    Liu, Lei; Liang, Renrong; Wang, Jing; Xiao, Lei; Xu, Jun

    2016-09-01

    GeSn/Ge tunneling field-effect transistors (TFETs) with different device configurations are comprehensively investigated by numerical simulation. The lateral PIN- and PNPN-type point-tunneling and vertical line-tunneling device structures are analyzed and compared. Both n- and p-type TFETs are optimized to construct GeSn complementary logic applications. Simulation results indicate that GeSn/Ge heterochannel and heterosource structures significantly improve the device characteristics of point- and line-TFETs, respectively. Device performance and subthreshold swing can be further improved by increasing the Sn composition. GeSn/Ge heterosource line-TFETs exhibit excellent device performance and superior inverter voltage-transfer characteristic, which make them promising candidates for GeSn complementary TFET applications.

  3. Femtosecond laser crystallization of amorphous Ge

    Science.gov (United States)

    Salihoglu, Omer; Kürüm, Ulaş; Yaglioglu, H. Gul; Elmali, Ayhan; Aydinli, Atilla

    2011-06-01

    Ultrafast crystallization of amorphous germanium (a-Ge) in ambient has been studied. Plasma enhanced chemical vapor deposition grown a-Ge was irradiated with single femtosecond laser pulses of various durations with a range of fluences from below melting to above ablation threshold. Extensive use of Raman scattering has been employed to determine post solidification features aided by scanning electron microscopy and atomic force microscopy measurements. Linewidth of the Ge optic phonon at 300 cm-1 as a function of laser fluence provides a signature for the crystallization of a-Ge. Various crystallization regimes including nanostructures in the form of nanospheres have been identified.

  4. The ternary germanides UMnGe and U2Mn3Ge

    Science.gov (United States)

    Hoffmann, Rolf-Dieter; Pöttgen, Rainer; Chevalier, Bernard; Gaudin, Etienne; Matar, Samir F.

    2013-07-01

    The title compounds were prepared by induction levitation melting of the elemental components and subsequent annealing. UMnGe (Pnma, a = 686.12(9), b = 425.49(6) and c = 736.5(1) pm) adopts the orthorhombic structure of TiNiSi and U2Mn3Ge (P63/mmc, a = 524.3(2) and c = 799.2(3) pm) possesses the hexagonal Mg2Cu3Si-type structure (ordered variant of the hexagonal Laves phase MgZn2). Both structures were refined from X-ray powder data to residuals of RI = 0.021 and 0.014 for UMnGe and U2Mn3Ge, respectively. The manganese and germanium atoms in UMnGe build up a three-dimensional [MnGe] network of ordered Mn3Ge3 hexagons with Mn-Ge distances ranging from 248 to 259 pm. The uranium atoms are coordinated by two tilted Mn3Ge3 hexagons. The manganese atoms in U2Mn3Ge build up Kagomé networks with 252 and 272 pm Mn-Mn distances which are connected via the germanium atoms (254 pm Mn-Ge) to a three-dimensional network. A remarkable feature of the U2Mn3Ge structure is a short U-U distance of 278 pm between adjacent cavities of the [Mn3Ge] network. From DFT based electronic structure calculations both germanides are found more cohesive than the Laves phase UMn2, thus underpinning the substantial role of Mn-Ge bonding. Calculations for both germanides show ferrimagnetic ground states with antiparallel spin alignments between U and Mn. The valence bands show bonding characteristics for interactions of atoms of different chemical natures and significant Mn-Mn bonding in U2Mn3Ge. Preliminary investigation of UMnGe by magnetization measurements confirms an antiferromagnetic arrangement below TN = 240 K.

  5. GeSn/SiGeSn photonic devices for mid-infrared applications: experiments and calculations

    Science.gov (United States)

    Han, Genquan; Zhang, Qingfang; Liu, Yan; Zhang, Chunfu; Hao, Yue

    2016-11-01

    In this work, a fully strained GeSn photodetector with Sn atom percent of 8% is fabricated on Ge buffer on Si(001) substrate. The wavelength λ of light signals with obvious optical response for Ge0.92Sn0.08 photodetector is extended to 2 μm. The impacts of compressive strain introduced during the epitaxial growth of GeSn on Ge/Si are studied by simulation. Besides, the tensile strain engineering of GeSn photonic devices is also investigated. Lattice-matched GeSn/SiGeSn double heterostructure light emitting diodes (LEDs) with Si3N4 tensile liner stressor are designed to promote the further mid-infrared applications of GeSn photonic devices. With the releasing of the residual stress in Si3N4 liner, a large biaxial tensile strain is induced in GeSn active layer. Under biaxial tensile strain, the spontaneous emission rate rsp and internal quantum efficiency ηIQE for GeSn/SiGeSn LED are significantly improved.

  6. Room Temperature Ferromagnetic Mn:Ge(001

    Directory of Open Access Journals (Sweden)

    George Adrian Lungu

    2013-12-01

    Full Text Available We report the synthesis of a room temperature ferromagnetic Mn-Ge system obtained by simple deposition of manganese on Ge(001, heated at relatively high temperature (starting with 250 °C. The samples were characterized by low energy electron diffraction (LEED, scanning tunneling microscopy (STM, high resolution transmission electron microscopy (HRTEM, X-ray photoelectron spectroscopy (XPS, superconducting quantum interference device (SQUID, and magneto-optical Kerr effect (MOKE. Samples deposited at relatively elevated temperature (350 °C exhibited the formation of ~5–8 nm diameter Mn5Ge3 and Mn11Ge8 agglomerates by HRTEM, while XPS identified at least two Mn-containing phases: the agglomerates, together with a Ge-rich MnGe~2.5 phase, or manganese diluted into the Ge(001 crystal. LEED revealed the persistence of long range order after a relatively high amount of Mn (100 nm deposited on the single crystal substrate. STM probed the existence of dimer rows on the surface, slightly elongated as compared with Ge–Ge dimers on Ge(001. The films exhibited a clear ferromagnetism at room temperature, opening the possibility of forming a magnetic phase behind a nearly ideally terminated Ge surface, which could find applications in integration of magnetic functionalities on semiconductor bases. SQUID probed the co-existence of a superparamagnetic phase, with one phase which may be attributed to a diluted magnetic semiconductor. The hypothesis that the room temperature ferromagnetic phase might be the one with manganese diluted into the Ge crystal is formulated and discussed.

  7. Modeling of GE Appliances: Final Presentation

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, Jason C.; Vyakaranam, Bharat; Leistritz, Sean M.; Parker, Graham B.

    2013-01-31

    This report is the final in a series of three reports funded by U.S. Department of Energy Office of Electricity Delivery and Energy Reliability (DOE-OE) in collaboration with GE Appliances’ through a Cooperative Research and Development Agreement (CRADA) to describe the potential of GE Appliances’ DR-enabled appliances to provide benefits to the utility grid.

  8. The Ge(0 0 1) surface

    NARCIS (Netherlands)

    Zandvliet, Henricus J.W.

    2003-01-01

    Although germanium (Ge) (0 0 1) has a relatively small surface unit cell, this surface displays a wealth of fascinating phenomena. The Ge(0 0 1) surface is a prototypical example of a system possessing both a strong short-range interaction due to dimerization of the surface atoms, as well as an

  9. Si/SiGe MMIC's

    Science.gov (United States)

    Luy, Johann-Friedrich; Strohm, Karl M.; Sasse, Hans-Eckard; Schueppen, Andreas; Buechler, Josef; Wollitzer, Michael; Gruhle, Andreas; Schaeffler, Friedrich; Guettich, Ulrich; Klaassen, Andreas

    1995-04-01

    Silicon-based millimeter-wave integrated circuits (SIMMWIC's) can provide new solutions for near range sensor and communication applications in the frequency range above 50 GHz. This paper gives a survey on the state-of-the-art performance of this technology and on first applications. The key devices are IMPATT diodes for mm-wave power generation and detection in the self-oscillating mixer mode, p-i-n diodes for use in switches and phase shifters, and Schottky diodes in detector and mixer circuits. The silicon/silicon germanium heterobipolar transistor (SiGe HBT) with f(sub max) values of more than 90 GHz is now used for low-noise oscillators at Ka-band frequencies. First system applications are discussed.

  10. HV/CVD Grown Relaxed SiGe Buffer Layers for SiGe HMOSFETs

    Institute of Scientific and Technical Information of China (English)

    黄文韬; 罗广礼; 史进; 邓宁; 陈培毅; 钱佩信

    2003-01-01

    High-vacuum/chemical-vapor deposition (HV/CVD) system was used to grow relaxed SiGe buffer layers on Si substrates. Several methods were then used to analyze the quality of the SiGe films. X-ray diffraction and Raman spectroscopy showed that the upper layer was almost fully relaxed. Second ion mass spectroscopy showed that the Ge compositions were step-graded. Transmission electron microscopy showed that the misfit dislocations were restrained to the graded SiGe layers. Tests of the electrical properties of tensile-strained Si on relaxed SiGe buffer layers showed that their transconductances were higher than that of Si devices. These results verify the high quality of the relaxed SiGe buffer layer. The calculated critical layer thicknesses of the graded Si1-xGex layer on Si substrate and a Si layer on the relaxed SiGe buffer layer agree well with experimental results.

  11. Ge/GeSn heterostructures grown on Si (100) by molecular-beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Sadofyev, Yu. G., E-mail: sadofyev@hotmail.com; Martovitsky, V. P.; Bazalevsky, M. A.; Klekovkin, A. V. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Averyanov, D. V.; Vasil’evskii, I. S. [National Research Nuclear University MEPhI (Russian Federation)

    2015-01-15

    The growth of GeSn layers by molecular-beam epitaxy on Si (100) wafers coated with a germanium buffer layer is investigated. The properties of the fabricated structures are controlled by reflection high-energy electron diffraction, atomic-force microscopy, X-ray diffractometry, Rutherford backscattering, and Raman scattering. It is shown that GeSn layers with thicknesses up to 0.5 μm and Sn molar fractions up to 0.073 manifest no sign of plastic relaxation upon epitaxy. The lattice constant of the GeSn layers within the growth plane is precisely the same as that of Ge. The effect of rapid thermal annealing on the conversion of metastable elastically strained GeSn layers into a plastically relaxed state is examined. Ge/GeSn quantum wells with Sn molar fraction up to 0.11 are obtained.

  12. Infrared photoresponse of GeSn/n-Ge heterojunctions grown by molecular beam epitaxy.

    Science.gov (United States)

    Kim, Sangcheol; Bhargava, Nupur; Gupta, Jay; Coppinger, Matthew; Kolodzey, James

    2014-05-05

    Heterojunction devices of Ge(1-x)Sn(x) / n-Ge were grown by solid source molecular beam epitaxy (MBE), and the mid-infrared (IR) photocurrent response was measured. With increasing Sn composition from 4% to 12%, the photocurrent spectra became red-shifted, suggesting that the bandgap of Ge(1-x)Sn(x) alloys was lowered compared to pure Ge. At a temperature of 100 K, the wavelengths of peak photocurrent were shifted from 1.42 µm for pure Ge (0% Sn) to 2.0 µm for 12% Sn. The bias dependence of the device response showed that the optimum reverse bias was > 0.5 volts for saturated photocurrent. The responsivity of the Ge(1-x)Sn(x) devices was estimated to be 0.17 A/W for 4% Sn. These results suggest that Ge(1-x)Sn(x) photodetectors may have practical applications in the near/mid IR wavelength regime.

  13. Pseudomorphic GeSn/Ge(001) quantum wells: Examining indirect band gap bowing

    Energy Technology Data Exchange (ETDEWEB)

    Tonkikh, Alexander A. [Max Planck Institute of Microstructure Physics, Weinberg 2 D-06120, Halle (Saale) (Germany); Institute for Physics of Microstructures RAS, GSP-105, Nizhniy Novgorod (Russian Federation); Eisenschmidt, Christian; Schmidt, Georg [Institute of Physics, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 3 D-01620, Halle (Saale) (Germany); Talalaev, Vadim G. [Max Planck Institute of Microstructure Physics, Weinberg 2 D-06120, Halle (Saale) (Germany); ZIK SiLi-Nano, Martin Luther University Halle-Wittenberg, Karl-Freiherr-von-Fritsch-Str. 3 D-06120, Halle (Saale) (Germany); Zakharov, Nikolay D.; Werner, Peter [Max Planck Institute of Microstructure Physics, Weinberg 2 D-06120, Halle (Saale) (Germany); Schilling, Joerg [ZIK SiLi-Nano, Martin Luther University Halle-Wittenberg, Karl-Freiherr-von-Fritsch-Str. 3 D-06120, Halle (Saale) (Germany)

    2013-07-15

    A study of the bandgap character of compressively strained GeSn{sub 0.060-0.091}/Ge(001) quantum wells grown by molecular beam epitaxy is reported. The built-in strain in GeSn wells leads to an increased separation between L and {Gamma} conduction band minima. The prevalent indirect interband transitions in GeSn were probed by photoluminescence spectroscopy. As a result we could simulate the L-valley bowing parameter in GeSn alloys, b{sub L} = 0.80 {+-} 0.06 eV at 10 K. From this we conclude that even compressively strained GeSn/Ge(001) alloys could become direct band gap semiconductors at the Sn-fraction higher than 17.0 at. %.

  14. Determination of Ge content in high concentration Ge-doped Czochralski Si single crystals by FTIR

    Institute of Scientific and Technical Information of China (English)

    JIANG Zhongwei; ZHANG Weilian; NIU Xinhuan

    2005-01-01

    SiGe single crystals with different Ge concentrations were measured by Fourier transform infrared (FTIR) spectroscopy at room temperature (RT) and 10 K. A new peak appears at the wave number of 710 cm-1 and the spectroscopy becomes clearer with an increase in Ge content. The absorption strength and wave sharp of the 710 cm-1 peak are independent of temperature. The relation of the absorption coefficient amax, the band width of half maximum (BWHM) W1/2 of the 710 cm-1 peak, and the Ge concentration is determined with the Ge content obtained by SEM-EDX. The conversion factor is k = 1.211 at 10 K. Therefore, the Ge content in high concentration Ge doped CZ-Si single crystals can be determined by FTIR.

  15. Ferromagnetic germanide in Ge nanowire transistors for spintronics application.

    Science.gov (United States)

    Tang, Jianshi; Wang, Chiu-Yen; Hung, Min-Hsiu; Jiang, Xiaowei; Chang, Li-Te; He, Liang; Liu, Pei-Hsuan; Yang, Hong-Jie; Tuan, Hsing-Yu; Chen, Lih-Juann; Wang, Kang L

    2012-06-26

    To explore spintronics applications for Ge nanowire heterostructures formed by thermal annealing, it is critical to develop a ferromagnetic germanide with high Curie temperature and take advantage of the high-quality interface between Ge and the formed ferromagnetic germanide. In this work, we report, for the first time, the formation and characterization of Mn(5)Ge(3)/Ge/Mn(5)Ge(3) nanowire transistors, in which the room-temperature ferromagnetic germanide was found through the solid-state reaction between a single-crystalline Ge nanowire and Mn contact pads upon thermal annealing. The atomically clean interface between Mn(5)Ge(3) and Ge with a relatively small lattice mismatch of 10.6% indicates that Mn(5)Ge(3) is a high-quality ferromagnetic contact to Ge. Temperature-dependent I-V measurements on the Mn(5)Ge(3)/Ge/Mn(5)Ge(3) nanowire heterostructure reveal a Schottky barrier height of 0.25 eV for the Mn(5)Ge(3) contact to p-type Ge. The Ge nanowire field-effect transistors built on the Mn(5)Ge(3)/Ge/Mn(5)Ge(3) heterostructure exhibit a high-performance p-type behavior with a current on/off ratio close to 10(5), and a hole mobility of 150-200 cm(2)/(V s). Temperature-dependent resistance of a fully germanided Mn(5)Ge(3) nanowire shows a clear transition behavior near the Curie temperature of Mn(5)Ge(3) at about 300 K. Our findings of the high-quality room-temperature ferromagnetic Mn(5)Ge(3) contact represent a promising step toward electrical spin injection into Ge nanowires and thus the realization of high-efficiency spintronic devices for room-temperature applications.

  16. Formation, structure and properties of GeCn± and Ge2Cn± binary clusters

    Institute of Scientific and Technical Information of China (English)

    CAO Yali; LI Guoliang; TANG Zichao

    2005-01-01

    The binary cluster ions Ge2Cn+/Ge2Cn- and GeCn+ have been produced by laser ablation. The parity effect is present in the negative ions Ge2Cn-, though it is not very prominent. While the experiments tell that the parity effect is totally not shown in the positive ions Ge2Cn+. An extensive theoretical investigation on GeCn/GeCn+/GeCn-(n = 1-10) and Ge2Cn/Ge2Cn+/Ge2Cn-(n = 1-9) has been carried out by density functional theory at B3LPY level. The calculation shows that the low-lying states of GeCn/GeCn+/GeCn-(n = 1-10) and Ge2Cn/Ge2Cn+/Ge2Cn-(n = 1-9) are linear structure with germanium atoms locating at terminals respectively. The electronic distributions, ionization potential (IPad), electron affinity (EA) and increasing bonding energy reveal that the parity effect of neutral species is much stronger than that of ions, which is attributed to the valence π-electrons. It is explained that the differences between experiments and calculations are due to the kinetic factor in the formation of Ge2Cn±.

  17. Epitaxial Growth of GeGaAs.

    Science.gov (United States)

    1981-06-01

    liquid solvent for epitaxial growth of Ge. Because of the finite solubility of GaAs in Pb (7 x 10-4 atomic fraction at 500°C) relatively fast initial...mixture of Pb and Sn was used as a melt. The solubility of Ge in a PbSn eutetic mixture is significantly higher than the solubility of Ge in pure Pb...shallow donor acceptor levels. Addition of a deep level to the crystal lat- tice at this point would further pin the fermi level near mid-gap

  18. I8As21Ge25

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available Single crystals of octaiodine henacosarsenic pentacosagermanium were grown by chemical transport reactions. The structure is isotypic with the analogous clathrates-I. In this structure, the statistically occupied clathrand atoms (As,Ge46 form bonds in a distorted tetrahedral coordination and their arrangement can define two polyhedra of different sizes; one is an (As,Ge20 pentagonal dodecahedron, and the other is an (As,Ge24 tetrakaidecahedron. The guest atom (iodine resides inside these polyhedra with site symmetry m3 (Wyckoff position 2a and overline{4}2m (Wyckoff position 6d, respectively.

  19. Experimental determination of the Ta–Ge phase diagram

    Energy Technology Data Exchange (ETDEWEB)

    Araújo Pinto da Silva, Antonio Augusto, E-mail: aaaps@ppgem.eel.usp.br [EEL/USP – Escola de Engenharia de Lorena (EEL), Universidade de São Paulo (USP), Pólo Urbo-Industrial Gleba AI-6, 12602-810 Lorena, SP (Brazil); Coelho, Gilberto Carvalho [EEL/USP – Escola de Engenharia de Lorena (EEL), Universidade de São Paulo (USP), Pólo Urbo-Industrial Gleba AI-6, 12602-810 Lorena, SP (Brazil); UniFoa – Centro Universitário de Volta Redonda, Núcleo de Pesquisa, Campus Três Poços, Avenida Paulo Erlei Alves Abrantes, 1325, Bairro Três Poços, 27240-560 Volta Redonda, RJ (Brazil); Nunes, Carlos Angelo; Suzuki, Paulo Atsushi [EEL/USP – Escola de Engenharia de Lorena (EEL), Universidade de São Paulo (USP), Pólo Urbo-Industrial Gleba AI-6, 12602-810 Lorena, SP (Brazil); Fiorani, Jean Marc; David, Nicolas; Vilasi, Michel [Université de Lorraine, Institut Jean Lamour, Faculté des Sciences et Technologies, BP 70239, F-54506 Vandoeuvre-lès-Nancy (France)

    2013-11-05

    Highlights: •Ta–Ge phase diagram propose for the first time. •The phase αTa{sub 5}Ge{sub 3} was not observed in samples investigated in this work. •Three eutectics reactions where determined with the liquid compositions at 20.5; 28.0; 97.0 at.% Ge. -- Abstract: In the present work, the Ta–Ge phase diagram has been experimentally studied, considering the inexistence of a Ta–Ge phase diagram in the literature. The samples were prepared via arc melting and characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD). The intermetallics phases βTa{sub 3}Ge, αTa{sub 3}Ge, βTa{sub 5}Ge{sub 3} and TaGe{sub 2} where confirmed in this system. Three eutectics reactions where determined with the liquid compositions at 20.5; 28.0; 97.0 at.% Ge. The phases βTa{sub 3}Ge and βTa{sub 5}Ge{sub 3} solidifies congruently while TaGe{sub 2} is formed through a peritectic transformation. The temperature of the Ta-rich eutectic (L ↔ Ta{sub ss} + βTa{sub 3}Ge) was measured by the Pirani-Alterthum method at 2440 °C and the Ge-rich eutectic (L ↔ TaGe{sub 2} + Ge{sub ss}) by DTA at 937 °C.

  20. Density Functional Theory Study on Mechanism of Forming Spiro-Ge-heterocyclic Ring Compound from Me2Ge=Ge: and Acetaldehyde

    Institute of Scientific and Technical Information of China (English)

    Xiu-hui Lu; Yong-qing Li; Wei-jie Bao; Dong-ting Liu

    2013-01-01

    The H2Ge=Ge:,as well as and its derivatives (X2Ge=Ge:,X=H,Me,F,CI,Br,Ph,Ar,...)is a kind of new species.Its cycloaddition reactions is a new area for the study of germylene chemistry.The mechanism of the cycloaddition reaction between singlet Me2Ge=Ge:and acetaldehyde was investigated with the B3LYP/6-31G* method in this work.From the potential energy profile,it could be predicted that the reaction has one dominant reaction pathway.The reaction rule is that the two reactants firstly form a four-membered Ge-heterocyclic ring germylene through the [2+2] cycloaddition reaction.Because of the 4p unoccupied orbital of Ge:atom in the four-membered Ge-heterocyclic ring germylene and the π orbital of acetaldehyde forning a π-p donor-acceptor bond,the four-membered Ge-heterocyclic ring germylene further combines with acetaldehyde to form an intermediate.Because the Ge atom in intermediate happens sp3 hybridization after transition state,then,intermediate isomerizes to a spiro-Ge-heterocyclic ring compound via a transition state.The research result indicates the laws of cycloaddition reaction between Me2Ge=Ge:and acetaldehyde,and lays the theory foundation of the cycloaddition reaction between H2Ge=Ge:and its derivatives (X2Ge=Ge:,X=H,Me,F,Cl,Br,Ph,Ar) and asymmetric π-bonded compounds,which are significant for the synthesis of small-ring and spiro-Ge-heterocyclic ring compounds.

  1. I8Sb10Ge36

    Directory of Open Access Journals (Sweden)

    Mohammed Kars

    2010-06-01

    Full Text Available Single crystals of the title compound, octaiodide decaantimonate hexatriacontagermanide, were grown by chemical transport reactions. The structure is isotypic with the analogous clathrates-I. In this structure, the (Ge,Sb46 framework consists of statistically occupied Ge and Sb sites that atoms form bonds in a distorted tetrahedral arrangement. They form polyhedra that are covalently bonded to each other by shared faces. There are two polyhedra of different sizes, viz. a (Ge,Sb20 dodecahedron and a (Ge,Sb24 tetracosahedron in a 1:3 ratio. The guest atom (iodine resides inside these polyhedra with symmetry m3 (Wyckoff position 2a and overline{4}2m (Wyckoff position 2d, respectively.

  2. Ge Quantum Dot Infrared Imaging Camera Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Luna Innovations Incorporated proposes to develop a high performance Ge quantum dots-based infrared (IR) imaging camera on Si substrate. The high sensitivity, large...

  3. Acheivement of Nano-Scale SiGe Layer with Discrete Ge Mole Fraction Profile Using Batch-Type HVCVD

    Institute of Scientific and Technical Information of China (English)

    Gon-sub Lee; Tae-hun Shim; Jea-gun Park

    2004-01-01

    The strained Si grown on the relaxed SiGe-on-insulator C-MOSFET's is a promising device for the future system LSI devices with the design rule of sub-micron. The achievement of the discrete Ge mole fraction in the SiGe layer is a key engineering in low-temperature SiGe epitaxial growth using HVCVD. The pre-flow of GeH4 gas enhanced the Ge mole fraction and SiGe layer thickness. In addition, the Ge mole fraction and SiGe layer thickness increases with the gas ratio of GeH4/SiH4 + GeH4, process temperature, and gas flow time. However, the haze was produced if the Ge mole fraction is above 22wt%. The discrete-like Ge mole fraction with 22 wt% in 10 nm SiGe layer was obtained by the pre-flow of GeH4 for 10 s, the mixture gas ratio of GeH4/SiH4 + GeH4 of 67%, and the gas flow time for 150 s at the process temperature of 550 C.

  4. GeSn pin diodes: from pure Ge to direct-gap materials

    Science.gov (United States)

    Gallagher, James; Senaratne, Charutha; Xu, Chi; Aoki, Toshihiro; Kouvetakis, John; Menendez, Jose

    2015-03-01

    Complete n - i - p Ge1-ySny diode structures (y =0-0.09) were fabricated on Si substrates with Sn concentrations covering the entire range between pure Ge and direct-gap materials. The structures typically consist of a thick (>1 μm) n + + Ge buffer layer grown by Gas Source Molecular Epitaxy using Ge4H10 and either P(SiH3)3 or P(GeH3)3 , followed by a GeSn intrinsic layer (~ 500 nm), grown by Chemical Vapor Deposition (CVD) using Ge3H8 and SnD4, and a GeSn p-type top layer (~ 200 nm) grown by CVD using Ge3H8,SnD4andB2H6. Temperature-dependence of the I - V characteristics of these diodes as well as the forward-bias dependence of their electroluminescence (EL) signal were investigated, making it possible for the first time to extract the compositional dependence of parameters such as band gaps, activation energies, and dark currents. The EL spectra are dominated by direct-gap emission, which shifts from 1590 nm to 2300 nm, in agreement with photoluminescence results. DOD AFOSR FA9550-12-1-0208 and DOD AFOSR FA9550-13-1-0022.

  5. Polycondensation-type Ge nanofractal assembly

    Directory of Open Access Journals (Sweden)

    Zhiwen Chen

    2011-03-01

    Full Text Available The group IV semiconductors such as silicon (Si and germanium (Ge are unique materials with a wide range of technological applications. A versatile integrated device for the semiconductor industry is highly desirable for advanced applications. Notwithstanding the widespread application of Ge its use is not as extensive as that of Si, and nebulous domains in our understanding of its precise technical functions still remain. Previous nanostructures have either been one-dimensional nanomaterials such as nanowires, nanorods, nanobelts/nanoribbons, nanotubes, two-dimensional nanoscale thin films, or zero-dimensional nanoparticles, which all have integer dimensions. Herein, the non-integer dimensional Ge nanostructures, referred to as nanofractals, were successfully assembled by high-vacuum thermal evaporation techniques. We have found that the thermodynamically driven assemblies of Ge nanocrystals possess amazing nanostructures such as polycondensation-type Ge nanofractals with non-integer dimensions, thick branches and smooth edges, metastable gamma-Au0.6Ge0.4 nanocrystals, and a variety of interesting micro/nanometer-sized features. The results of computer simulations using a ripening mechanism of non-uniform grains agree very well with the patterns formed in experiments.

  6. Search for Tetrahedral Symmetry in 70Ge

    Science.gov (United States)

    Le, Khanh; Haring-Kaye, R. A.; Elder, R. M.; Jones, K. D.; Morrow, S. I.; Tabor, S. L.; Tripathi, V.; Bender, P. C.; Allegro, P. R. P.; Medina, N. H.; Oliveira, J. R. B.; Doring, J.

    2014-09-01

    The even-even Ge isotopes have recently become an active testing ground for a variety of exotic structural characteristics, including the existence of tetrahedral symmetry (pyramid-like shapes). Although theoretical shape calculations predict the onset of tetrahedral symmetry near 72Ge, the experimental signatures (including vanishing quadrupole moments within high-spin bands) remain elusive. This study searched for possible experimental evidence of tetrahedral symmetry in 70Ge. Excited states in 70Ge were populated at Florida State University using the 55Mn(18O,p2n) fusion-evaporation reaction at 50 MeV. Prompt γ- γ coincidences were measured with a Compton-suppressed Ge array consisting of three Clover detectors and seven single-crystal detectors. The existing level scheme was enhanced through the addition of 20 new transitions and the rearrangement of five others based on the measured coincidence relations and relative intensities. Lifetimes of 24 states were measured using the Doppler-shift attenuation method, from which transition quadrupole moments were inferred. These results will be compared with those obtained from cranked Woods-Saxon calculations. The even-even Ge isotopes have recently become an active testing ground for a variety of exotic structural characteristics, including the existence of tetrahedral symmetry (pyramid-like shapes). Although theoretical shape calculations predict the onset of tetrahedral symmetry near 72Ge, the experimental signatures (including vanishing quadrupole moments within high-spin bands) remain elusive. This study searched for possible experimental evidence of tetrahedral symmetry in 70Ge. Excited states in 70Ge were populated at Florida State University using the 55Mn(18O,p2n) fusion-evaporation reaction at 50 MeV. Prompt γ- γ coincidences were measured with a Compton-suppressed Ge array consisting of three Clover detectors and seven single-crystal detectors. The existing level scheme was enhanced through the addition

  7. Material gain engineering in GeSn/Ge quantum wells integrated with an Si platform

    Science.gov (United States)

    Mączko, H. S.; Kudrawiec, R.; Gladysiewicz, M.

    2016-09-01

    It is shown that compressively strained Ge1‑xSnx/Ge quantum wells (QWs) grown on a Ge substrate with 0.1 ≤ x ≤ 0.2 and width of 8 nm ≤ d ≤ 14 nm are a very promising gain medium for lasers integrated with an Si platform. Such QWs are type-I QWs with a direct bandgap and positive transverse electric mode of material gain, i.e. the modal gain. The electronic band structure near the center of Brillouin zone has been calculated for various Ge1‑xSnx/Ge QWs with use of the 8-band kp Hamiltonian. To calculate the material gain for these QWs, occupation of the L valley in Ge barriers has been taken into account. It is clearly shown that this occupation has a lot of influence on the material gain in the QWs with low Sn concentrations (Sn  15%). However, for QWs with Sn > 20% the critical thickness of a GeSn layer deposited on a Ge substrate starts to play an important role. Reduction in the QW width shifts up the ground electron subband in the QW and increases occupation of the L valley in the barriers instead of the Γ valley in the QW region.

  8. Performance Investigation of Nanoscale Strained Ge pMOSFETs with a GeSn Alloy Stressor.

    Science.gov (United States)

    Lee, Chang-Chun; Chang, Shu-Tong; Cheng, Sen-Wen; Chian, Bow-Tsin

    2015-11-01

    A germanium (Ge)-based substrate combined with germanium-tin (GeSn) alloy embedded in source/drain (S/D) regions has attracted significant attention because of its ability to satisfy the requirements of a high-mobility channel. Devices are shrunk in their geometries to meet the target of superior density in layout arrangement. Thus, determining the influences of devices on mobility gain is important. Accordingly, several designed factors, including gate width, S/D length, and Sn concentration of the GeSn stressor, are systematically analyzed in this study. A second-order formula composed of piezoresistance coefficients is derived and adopted to achieve a precise mobility gain estimation. A peak of the carrier mobility gain appears when a nanoscale geometry combination of 20 nm gate length and -200 nm gate width is used in the Ge channel, and 10% of the Sn mole proportion of the GeSn alloy is applied.

  9. Thermodynamic assessment of the Nb-Ge system

    Energy Technology Data Exchange (ETDEWEB)

    Geng Tai [School of Materials Science and Engineering, University of Science and Technology Beijing, Xueyuan Road, 30, Haidian District, Beijing 100083 (China); Li Changrong, E-mail: crli@mater.ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Xueyuan Road, 30, Haidian District, Beijing 100083 (China); Du Zhenmin; Guo Cuiping [School of Materials Science and Engineering, University of Science and Technology Beijing, Xueyuan Road, 30, Haidian District, Beijing 100083 (China); Zhao Xinqing; Xu Huibin [School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China)

    2011-02-10

    Research highlights: > For the phases Nb{sub 3}Ge{sub 2} and Nb{sub 3}Ge, the reasonable sublattice models were constructed. > A set of thermodynamic parameters for the Nb-Ge system was obtained. > The optimized result can interpreter the vaporization of Ge during preparation. - Abstract: The Nb-Ge binary system has been thermodynamically assessed using the CALPHAD (Calculation of Phase Diagrams) approach on the basis of the experimental data of both the phase equilibria and the thermochemical properties. The reasonable models were constructed for all the phases of the system. The liquid and the terminal solid solution phases, Bcc-(Nb) and Diamond-(Ge), were described as the substitutional solutions with Redlich-Kister polynomials for the expressions of the excess Gibbs free energies. The intermediate phases (Nb{sub 3}Ge), (Nb{sub 5}Ge{sub 3}), (Nb{sub 3}Ge{sub 2}) and (NbGe{sub 2}) with homogeneity ranges were treated as the sublattice models Nb{sub 0.75}(Ge,Nb,Va){sub 0.25}, Nb{sub 0.5}(Nb,Ge){sub 0.125}(Ge,Va){sub 0.375}, (Nb,Ge){sub 0.222}(Nb,Ge){sub 0.333}Nb{sub 0.333}(Ge,Va){sub 0.111} and (Nb,Ge){sub 0.333}(Nb,Ge){sub 0.667} respectively based on their structure features of atom arrangements. A set of self-consistent thermodynamic parameters for the Nb-Ge system was obtained. Using the present thermodynamic data, the calculation results can reproduce the experimental data well.

  10. Dopage p par BI3 de couches Ge/Ge ET Ge/GaAs; caractérisationélectrique

    Science.gov (United States)

    Étienne, D.; Achargui, N.; Bougnot, G.

    1986-01-01

    B doped Ge layers were obtained by chemical vapor transport using a disproportionation reaction 2GeI2=Ge+GeI4. They were p-type and their electric parameters: resistivity ϱ, Hall mobility μH and carrier concentration p were studied as a function of substrate temperature, partial pressure of BI3 and hydrogen flow rate on BI3 source. The incorporation of B into monocrystalline layers is studied thermodynamically.

  11. Structure of glassy GeO2.

    Science.gov (United States)

    Salmon, Philip S; Barnes, Adrian C; Martin, Richard A; Cuello, Gabriel J

    2007-10-17

    The full set of partial structure factors for glassy germania, or GeO2, were accurately measured by using the method of isotopic substitution in neutron diffraction in order to elucidate the nature of the pair correlations for this archetypal strong glass former. The results show that the basic tetrahedral Ge(O1/2)4 building blocks share corners with a mean inter-tetrahedral Ge-Ô-Ge bond angle of 132(2)°. The topological and chemical ordering in the resultant network displays two characteristic length scales at distances greater than the nearest neighbour. One of these describes the intermediate range order, and manifests itself by the appearance of a first sharp diffraction peak in the measured diffraction patterns at a scattering vector kFSDP≈1.53 Å(-1), while the other describes so-called extended range order, and is associated with the principal peak at kPP = 2.66(1) Å(-1). We find that there is an interplay between the relative importance of the ordering on these length scales for tetrahedral network forming glasses that is dominated by the extended range ordering with increasing glass fragility. The measured partial structure factors for glassy GeO2 are used to reproduce the total structure factor measured by using high energy x-ray diffraction and the experimental results are also compared to those obtained by using classical and first principles molecular dynamics simulations.

  12. Study of Si-Ge interdiffusion with phosphorus doping

    KAUST Repository

    Cai, Feiyang

    2016-10-28

    Si-Ge interdiffusion with phosphorus doping was investigated by both experiments and modeling. Ge/Si1-x Ge x/Ge multi-layer structures with 0.75Ge<1, a mid-1018 to low-1019 cm−3 P doping, and a dislocation density of 108 to 109 cm−2 range were studied. The P-doped sample shows an accelerated Si-Ge interdiffusivity, which is 2–8 times of that of the undoped sample. The doping dependence of the Si-Ge interdiffusion was modelled by a Fermi-enhancement factor. The results show that the Si-Ge interdiffusion coefficient is proportional to n2/n2i for the conditions studied, which indicates that the interdiffusion in a high Ge fraction range with n-type doping is dominated by V2− defects. The Fermi-enhancement factor was shown to have a relatively weak dependence on the temperature and the Ge fraction. The results are relevant to the structure and thermal processing condition design of n-type doped Ge/Si and Ge/SiGe based devices such as Ge/Si lasers.

  13. Clathrate formation in the systems Sr-Cu-Ge and {Ba,Sr}-Cu-Ge

    Science.gov (United States)

    Zeiringer, I.; Moser, R.; Kneidinger, F.; Podloucky, R.; Royanian, E.; Grytsiv, A.; Bauer, E.; Giester, G.; Falmbigl, M.; Rogl, P.

    2014-09-01

    In the ternary system Sr-Cu-Ge, a novel clathrate type-I phase was detected, Sr8CuxGe46-x (5.2≤xtemperature interval. Sr8Cu5.3Ge40.7 decomposes eutectoidally on cooling at 730±3 °C into (Ge), SrGe2 and τ1-SrCu2-xGe2+x. Phase equilibria at 700 °C have been established for the Ge rich part and are characterized by the appearance of only one ternary compound, τ1-SrCu2-xGe2+x, which crystallizes with the ThCr2Si2 structure type and forms a homogeneity range up to x=0.4 (a=0.42850(4), c=1.0370(1) nm). Additionally, the extent of the clathrate type-I solid solution Ba8-ySryCuxGe46-x (0≤y≤~5.6; 5.2≤x≤5.4, from as cast alloys) has been studied at various temperatures. The clathrate type-I crystal structure (space group Pm3barn) has been proven by X-ray single crystal diffraction on two single crystals with the composition (from refinement): Sr8Cu5.36Ge40.64 (a=1.06368(2) nm at 300 K) and Ba4.86Sr3.14Cu5.36Ge40.64 (a=1.06748(2) nm at 300 K) measured at 300, 200 and 100 K. From the temperature dependence of the lattice parameters and the atomic displacement parameters, thermal expansion coefficients, Debye- and Einstein-temperatures and the speed of sound have been determined. From heat capacity measurements of Sr8Cu5.3Ge40.7 at low temperatures the Sommerfeld coefficient (γ=24 mJ/mol K2) and the Debye temperature (ΘDLT=273 K) have been extracted. From a detailed analysis of these data at higher temperatures, Einstein branches of the phonon dispersion relation have been derived and compared to those obtained from the atomic displacement parameters. Electrical resistivity measurements of Sr8Cu5.3Ge40.7 reveal a rather metallic behavior in the low temperature range (<300 K). Density function theory calculations provide densities of states, electronic resistivity and Seebeck coefficient as well as the vibrational spectrum and specific heat.

  14. 45 CFR 2541.360 - Procurement.

    Science.gov (United States)

    2010-10-01

    ... in excess of $2500 for other contracts which involve the employment of mechanics or laborers) (7... transcriptions. (11) Retention of all required records for three years after grantees or subgrantees make final...

  15. 45 CFR 2541.250 - Program income.

    Science.gov (United States)

    2010-10-01

    ... them. (b) Definition of program income. Program income means gross income received by the grantee or... copyrighted material, patents, and inventions developed by a grantee or subgrantee is program income only...

  16. TMFunction data: 2541 [TMFunction[Archive

    Lifescience Database Archive (English)

    Full Text Available ductance (pS) ... Q3SAJ8_9BORD (Q3SAJ8) Helix ... amphipathic; activity; hemolytic activity; propensity; toxin pores ... ... Basler M, Knapp O, Masin J, Fiser R, Maier E, Benz R, Sebo P, Osicka R J Biol Chem. 2007 Apr 27;282(17):12419-29 Mutagenesis 40 Con

  17. 45 CFR 2541.40 - Applicability.

    Science.gov (United States)

    2010-10-01

    ... 412(e) of the Immigration and Nationality Act (8 U.S.C. 1522(e)) and subsection 501(a) of the Refugee... 241-1(a), and 242 through 244 (portions of the Impact Aid program), except for 20 U.S.C....

  18. 45 CFR 2541.220 - Allowable costs.

    Science.gov (United States)

    2010-10-01

    ... accounting standards that comply with cost principles acceptable to the Federal agency. ... the grantee or subgrantee. (b) Applicable cost principles. For each kind of organization, there is a set of Federal principles for determining allowable costs. Allowable costs will be determined...

  19. Multi-GeV Gluonic Mesons

    CERN Document Server

    Page, P R

    2001-01-01

    Lattice QCD gives reliable predictions for hybrid charmonium and multi-GeV glueball masses. Proton-antiproton annihilation may offer an excellent opportunity for the first observation of these states. There are two distinct possible programs: The search for J^PC-exotic and non-J^PC-exotic states. The latter program represents substantially higher cross sections and does not absolutely require partial wave analysis, two very attractive features. The program can be performed with a varying pbar energy <10 GeV and a fixed target.

  20. Tensile-strained Ge/SiGe quantum-well photodetectors on silicon substrates with extended infrared response.

    Science.gov (United States)

    Chang, Guo-En; Chen, Shao-Wei; Cheng, H H

    2016-08-08

    We report on tensile-strained Ge/Si0.11Ge0.89 quantum-well (QW) metal-semiconductor-metal (MSM) photodetectors on Si substrates. A tensile strain of 0.21% is introduced into the Ge wells by growing the QW stack on in-situ annealed Ge-on-Si virtual substrates (VS). The optical characterization of Ge/Si0.11Ge0.89 QW MSM photodetectors indicates that the optical response increases to a wavelength of 1.5 μm or higher owing to the strain-induced direct bandgap shrinkage. Analysis of the band structure by using a k · p model suggests that by optimizing the tensile strain and Ge well width, tensile-strained Ge/SiGe QW photodetectors can be designed to cover the telecommunication C-band and beyond for optical telecommunications and on-chip interconnection.

  1. Ultra-smooth epitaxial Ge grown on Si(001) utilizing a thin C-doped Ge buffer layer

    KAUST Repository

    Mantey, J.

    2013-01-01

    Here, we present work on epitaxial Ge films grown on a thin buffer layer of C doped Ge (Ge:C). The growth rate of Ge:C is found to slow over time and is thus unsuitable for thick (>20 nm) layers. We demonstrate Ge films from 10 nm to >150 nm are possible by growing pure Ge on a thin Ge:C buffer. It is shown that this stack yields exceedingly low roughness levels (comparable to bulk Si wafers) and contains fewer defects and higher Hall mobility compared to traditional heteroepitaxial Ge. The addition of C at the interface helps reduce strain by its smaller atomic radius and its ability to pin defects within the thin buffer layer that do not thread to the top Ge layer. © 2013 AIP Publishing LLC.

  2. Compton profile study of V3Ge and Cr3Ge

    Indian Academy of Sciences (India)

    Y C Sharma; V Vyas; V Purvia; K B Joshi; B K Sharma

    2008-02-01

    In this paper the results of a Compton profile study of two polycrystalline A15 compounds, namely, V3Ge and Cr3Ge, have been reported. The measurements have been performed using 59.54 keV -rays from an 241Am source. The theoretical Compton profiles have been computed for both the compounds using ab-initio linear combination of atomic orbitals (LCAO) method employing CRYSTAL98. For both the A15 compounds, the isotropic experimental profiles are found to be in good overall agreement with the calculations. The comparison points out residual differences in V3Ge whereas for Cr3Ge the differences are within experimental error. The behaviour of valence electrons in the two iso-structural compounds has been examined on the scale of Fermi momentum. The valence electron distribution seems to be dominated by the metallic constituents rather than Ge and two compounds show covalent nature of bonding which is larger in V3Ge compared to Cr3Ge.

  3. The Characterization of GeH_2 and GeH Using Matrix Isolation Infrared Spectroscopy

    Science.gov (United States)

    Amicangelo, Jay; Bailey, Christopher; Hoover, Madelyn; Huffman, Bruce

    2014-06-01

    Matrix isolation infrared spectroscopy was used to characterize the fundamental infrared peaks of the germanium hydride species GeH_2 and GeH in low temperature argon matrices that result from the vacuum-ultraviolet (VUV) photolysis of germane (GeH_4). Experiments were performed by depositing mixtures of GeH_4 with argon onto a CsI window cooled to 12 K while simultaneously photolyzing the mixture with 121 nm VUV radiation from a hydrogen resonance lamp. For GeH_2, the fundamental infrared peaks are observed at 1839.1 wn (νb{3}, antisymmetric stretch), 1816.6 wn (νb{1}, symmetric stretch) and 913.4 wn (νb{2}, bend). For GeH, the fundamental infrared stretching peak is observed at 1813.4 wn. The assignment of the observed peaks is established by performing experiments with isotopic germane (GeD_4), by performing matrix annealing experiments (warming to 25 - 35 K and refreezing to 12 K), by performing mercury-xenon lamp matrix photolysis experiments (200 - 900 nm), and by comparison to quantum chemical calculations performed at the B3LYP and MP2 levels of theory. This work corrects what appears to be incorrect assignments made in the earlier report of Smith and Guillory G. R. Smith and W. A. Guillory, J. Chem. Phys., 56, 1423 (1972).

  4. Novel Ge waveguide platform on Ge-on-insulator wafer for mid-infrared photonic integrated circuits.

    Science.gov (United States)

    Kang, Jian; Takenaka, Mitsuru; Takagi, Shinichi

    2016-05-30

    We present Ge rib waveguide devices fabricated on a Ge-on-insulator (GeOI) wafer as a proof-of-concept Ge mid-infrared photonics platform. Numerical analysis revealed that the driving current for a given optical attenuation in a carrier-injection Ge waveguide device at a 1.95 μm wavelength can be approximately five times smaller than that in a Si device, enabling in-line carrier-injection Ge optical modulators based on free-carrier absorption. We prepared a GeOI wafer with a 2-μm-thick buried oxide layer (BOX) by wafer bonding. By using the GeOI wafer, we fabricated Ge rib waveguides. The Ge rib waveguides were transparent to 2 μm wavelengths and the propagation loss was found to be 1.4 dB/mm, which may have been caused by sidewall scattering. We achieved a negligible bend loss in the Ge rib waveguide, even with a 5 μm bend radius, owing to the strong optical confinement in the GeOI structure. We also formed a lateral p-i-n junction along the Ge rib waveguide to explore the capability of absorption modulation by carrier injection. By injecting current through the lateral p-i-n junction, we achieved optical intensity modulation in the 2 μm band based on the free-carrier absorption in Ge.

  5. Study of a SiGeSn/GeSn/SiGeSn structure toward direct bandgap type-I quantum well for all group-IV optoelectronics.

    Science.gov (United States)

    Ghetmiri, Seyed Amir; Zhou, Yiyin; Margetis, Joe; Al-Kabi, Sattar; Dou, Wei; Mosleh, Aboozar; Du, Wei; Kuchuk, Andrian; Liu, Jifeng; Sun, Greg; Soref, Richard A; Tolle, John; Naseem, Hameed A; Li, Baohua; Mortazavi, Mansour; Yu, Shui-Qing

    2017-02-01

    A SiGeSn/GeSn/SiGeSn single quantum well structure was grown using an industry standard chemical vapor deposition reactor with low-cost commercially available precursors. The material characterization revealed the precisely controlled material growth process. Temperature-dependent photoluminescence spectra were correlated with band structure calculation for a structure accurately determined by high-resolution x-ray diffraction and transmission electron microscopy. Based on the result, a systematic study of SiGeSn and GeSn bandgap energy separation and barrier heights versus material compositions and strain was conducted, leading to a practical design of a type-I direct bandgap quantum well.

  6. Vertical Ge and GeSn heterojunction gate-all-around tunneling field effect transistors

    Science.gov (United States)

    Schulze, Jörg; Blech, Andreas; Datta, Arnab; Fischer, Inga A.; Hähnel, Daniel; Naasz, Sandra; Rolseth, Erlend; Tropper, Eva-Maria

    2015-08-01

    We present experimental results on the fabrication and characterization of vertical Ge and GeSn heterojunction Tunneling Field Effect Transistors (TFETs). A gate-all-around process with mesa diameters down to 70 nm is used to reduce leakage currents and improve electrostatic control of the gate over the transistor channel. An ION = 88.4 μA/μm at VDS = VG = -2 V is obtained for a TFET with a 10 nm Ge0.92Sn0.08 layer at the source/channel junction. We discuss further possibilities for device improvements.

  7. Ratio of Jet Cross Sections at s = 630 GeV and 1800 GeV

    Science.gov (United States)

    Abbott, B.; Abolins, M.; Abramov, V.; Acharya, B. S.; Adams, D. L.; Adams, M.; Alves, G. A.; Amos, N.; Anderson, E. W.; Baarmand, M. M.; Babintsev, V. V.; Babukhadia, L.; Baden, A.; Baldin, B.; Balm, P. W.; Banerjee, S.; Bantly, J.; Barberis, E.; Baringer, P.; Bartlett, J. F.; Bassler, U.; Bean, A.; Begel, M.; Belyaev, A.; Beri, S. B.; Bernardi, G.; Bertram, I.; Besson, A.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Bhattacharjee, M.; Blazey, G.; Blessing, S.; Boehnlein, A.; Bojko, N. I.; Borcherding, F.; Brandt, A.; Breedon, R.; Briskin, G.; Brock, R.; Brooijmans, G.; Bross, A.; Buchholz, D.; Buehler, M.; Buescher, V.; Burtovoi, V. S.; Butler, J. M.; Canelli, F.; Carvalho, W.; Casey, D.; Casilum, Z.; Castilla-Valdez, H.; Chakraborty, D.; Chan, K. M.; Chekulaev, S. V.; Cho, D. K.; Choi, S.; Chopra, S.; Christenson, J. H.; Chung, M.; Claes, D.; Clark, A. R.; Cochran, J.; Coney, L.; Connolly, B.; Cooper, W. E.; Coppage, D.; Cummings, M. A.; Cutts, D.; Dahl, O. I.; Davis, G. A.; Davis, K.; de, K.; del Signore, K.; Demarteau, M.; Demina, R.; Demine, P.; Denisov, D.; Denisov, S. P.; Desai, S.; Diehl, H. T.; Diesburg, M.; di Loreto, G.; Doulas, S.; Draper, P.; Ducros, Y.; Dudko, L. V.; Duensing, S.; Dugad, S. R.; Dyshkant, A.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O. V.; Estrada, J.; Evans, H.; Evdokimov, V. N.; Fahland, T.; Feher, S.; Fein, D.; Ferbel, T.; Fisk, H. E.; Fisyak, Y.; Flattum, E.; Fleuret, F.; Fortner, M.; Frame, K. C.; Fuess, S.; Gallas, E.; Galyaev, A. N.; Gartung, P.; Gavrilov, V.; Genik, R. J.; Genser, K.; Gerber, C. E.; Gershtein, Y.; Gibbard, B.; Gilmartin, R.; Ginther, G.; Gómez, B.; Gómez, G.; Goncharov, P. I.; González Solís, J. L.; Gordon, H.; Goss, L. T.; Gounder, K.; Goussiou, A.; Graf, N.; Graham, G.; Grannis, P. D.; Green, J. A.; Greenlee, H.; Grinstein, S.; Groer, L.; Grudberg, P.; Grünendahl, S.; Gupta, A.; Gurzhiev, S. N.; Gutierrez, G.; Gutierrez, P.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hahn, K. S.; Hall, R. E.; Hanlet, P.; Hansen, S.; Hauptman, J. M.; Hays, C.; Hebert, C.; Hedin, D.; Heinson, A. P.; Heintz, U.; Heuring, T.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hoftun, J. S.; Hou, S.; Huang, Y.; Ito, A. S.; Jerger, S. A.; Jesik, R.; Johns, K.; Johnson, M.; Jonckheere, A.; Jones, M.; Jöstlein, H.; Juste, A.; Kahn, S.; Kajfasz, E.; Karmanov, D.; Karmgard, D.; Kehoe, R.; Kim, S. K.; Klima, B.; Klopfenstein, C.; Knuteson, B.; Ko, W.; Kohli, J. M.; Kostritskiy, A. V.; Kotcher, J.; Kotwal, A. V.; Kozelov, A. V.; Kozlovsky, E. A.; Krane, J.; Krishnaswamy, M. R.; Krzywdzinski, S.; Kubantsev, M.; Kuleshov, S.; Kulik, Y.; Kunori, S.; Kuznetsov, V. E.; Landsberg, G.; Leflat, A.; Lehner, F.; Li, J.; Li, Q. Z.; Lima, J. G.; Lincoln, D.; Linn, S. L.; Linnemann, J.; Lipton, R.; Lucotte, A.; Lueking, L.; Lundstedt, C.; Maciel, A. K.; Madaras, R. J.; Manankov, V.; Mao, H. S.; Marshall, T.; Martin, M. I.; Martin, R. D.; Mauritz, K. M.; May, B.; Mayorov, A. A.; McCarthy, R.; McDonald, J.; McMahon, T.; Melanson, H. L.; Meng, X. C.; Merkin, M.; Merritt, K. W.; Miao, C.; Miettinen, H.; Mihalcea, D.; Mincer, A.; Mishra, C. S.; Mokhov, N.; Mondal, N. K.; Montgomery, H. E.; Moore, R. W.; Mostafa, M.; da Motta, H.; Nagy, E.; Nang, F.; Narain, M.; Narasimham, V. S.; Neal, H. A.; Negret, J. P.; Negroni, S.; Norman, D.; Oesch, L.; Oguri, V.; Olivier, B.; Oshima, N.; Padley, P.; Pan, L. J.; Para, A.; Parashar, N.; Partridge, R.; Parua, N.; Paterno, M.; Patwa, A.; Pawlik, B.; Perkins, J.; Peters, M.; Peters, O.; Piegaia, R.; Piekarz, H.; Pope, B. G.; Popkov, E.; Prosper, H. B.; Protopopescu, S.; Qian, J.; Quintas, P. Z.; Raja, R.; Rajagopalan, S.; Ramberg, E.; Rapidis, P. A.; Reay, N. W.; Reucroft, S.; Rha, J.; Rijssenbeek, M.; Rockwell, T.; Roco, M.; Rubinov, P.; Ruchti, R.; Rutherfoord, J.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Schellman, H.; Schwartzman, A.; Sculli, J.; Sen, N.; Shabalina, E.; Shankar, H. C.; Shivpuri, R. K.; Shpakov, D.; Shupe, M.; Sidwell, R. A.; Simak, V.; Singh, H.; Singh, J. B.; Sirotenko, V.; Slattery, P.; Smith, E.; Smith, R. P.; Snihur, R.; Snow, G. R.; Snow, J.; Snyder, S.; Solomon, J.; Sorín, V.; Sosebee, M.; Sotnikova, N.; Soustruznik, K.; Souza, M.; Stanton, N. R.; Steinbrück, G.; Stephens, R. W.; Stevenson, M. L.; Stichelbaut, F.; Stoker, D.; Stolin, V.; Stoyanova, D. A.; Strauss, M.; Streets, K.; Strovink, M.; Stutte, L.; Sznajder, A.; Taylor, W.; Tentindo-Repond, S.; Thompson, J.; Toback, D.; Tripathi, S. M.; Trippe, T. G.; Turcot, A. S.; Tuts, P. M.; van Gemmeren, P.; Vaniev, V.; van Kooten, R.; Varelas, N.; Volkov, A. A.; Vorobiev, A. P.; Wahl, H. D.; Wang, H.; Wang, Z.-M.; Warchol, J.; Watts, G.; Wayne, M.; Weerts, H.; White, A.; White, J. T.; Whiteson, D.; Wightman, J. A.; Wijngaarden, D. A.; Willis, S.; Wimpenny, S. J.; Wirjawan, J. V.; Womersley, J.; Wood, D. R.; Yamada, R.; Yamin, P.; Yasuda, T.; Yip, K.; Youssef, S.; Yu, J.; Yu, Z.; Zanabria, M.; Zheng, H.; Zhou, Z.; Zhu, Z. H.; Zielinski, M.; Zieminska, D.; Zieminski, A.; Zutshi, V.; Zverev, E. G.; Zylberstejn, A.

    2001-03-01

    The D0 Collaboration has measured the inclusive jet cross section in p¯p collisions at s = 630 GeV. The results for pseudorapidities η<0.5 are combined with our previous results at s = 1800 GeV to form a ratio of cross sections with smaller uncertainties than either individual measurement. Next-to-leading-order QCD predictions show excellent agreement with the measurement at 630 GeV; agreement is also satisfactory for the ratio. Specifically, despite a 10% to 15% difference in the absolute magnitude, the dependence of the ratio on jet transverse momentum is very similar for data and theory.

  8. Distribution and Substitution Mechanism of Ge in a Ge-(Fe-Bearing Sphalerite

    Directory of Open Access Journals (Sweden)

    Nigel J. Cook

    2015-03-01

    Full Text Available The distribution and substitution mechanism of Ge in the Ge-rich sphalerite from the Tres Marias Zn deposit, Mexico, was studied using a combination of techniques at μm- to atomic scales. Trace element mapping by Laser Ablation Inductively Coupled Mass Spectrometry shows that Ge is enriched in the same bands as Fe, and that Ge-rich sphalerite also contains measurable levels of several other minor elements, including As, Pb and Tl. Micron- to nanoscale heterogeneity in the sample, both textural and compositional, is revealed by investigation using Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM combined with Synchrotron X-ray Fluorescence mapping and High-Resolution Transmission Electron Microscopy imaging of FIB-prepared samples. Results show that Ge is preferentially incorporated within Fe-rich sphalerite with textural complexity finer than that of the microbeam used for the X-ray Absorption Near Edge Structure (XANES measurements. Such heterogeneity, expressed as intergrowths between 3C sphalerite and 2H wurtzite on  zones, could be the result of either a primary growth process, or alternatively, polystage crystallization, in which early Fe-Ge-rich sphalerite is partially replaced by Fe-Ge-poor wurtzite. FIB-SEM imaging shows evidence for replacement supporting the latter. Transformation of sphalerite into wurtzite is promoted by (111* twinning or lattice-scale defects, leading to a heterogeneous ZnS sample, in which the dominant component, sphalerite, can host up to ~20% wurtzite. Ge K-edge XANES spectra for this sphalerite are identical to those of the germanite and argyrodite standards and the synthetic chalcogenide glasses GeS2 and GeSe2, indicating the Ge formally exists in the tetravalent form in this sphalerite. Fe K-edge XANES spectra for the same sample indicate that Fe is present mainly as Fe2+, and Cu K-edge XANES spectra are characteristic for Cu+. Since there is no evidence for coupled substitution involving a monovalent

  9. The low temperature epitaxy of Ge on Si (1 0 0) substrate using two different precursors of GeH4 and Ge2H6

    Science.gov (United States)

    Kil, Yeon-Ho; Yuk, Sim-Hoon; Kim, Joung Hee; Kim, Taek Sung; Kim, Yong Tae; Choi, Chel-Jong; Shim, Kyu-Hwan

    2016-10-01

    We have investigated the initial stage of low temperature epitaxy (LTE) of Ge on 8″-dia. Si (1 0 0) substrate using a rapid thermal chemical vapor deposition (RTCVD) with two different precursors of GeH4 and Ge2H6. The quality of LTE Ge films such as surface morphology, defects and crystallinity were analyzed using SEM, AFM and TEM. Experimental results confirmed that the LTE Ge using Ge2H6 precursor was much more beneficial than the LTE using GeH4 in terms of growth rate (×10), stress relaxation (85% at surface), and crystal quality (low TDDs). The discrepancy looks originated from the weak Gesbnd Ge bonds requiring their dissociation energy small compared to the Gesbnd H bonds in GeH4 precursors, and the abundant supply of GeH3 molecules should stimulate chemical reactions at free surface sites. Our LTE technology would be promising for very thin Ge virtual substrate as well as be beneficial for nano-micro electronic devices in need of low temperature processes below 300-500 °C.

  10. Synthesis and Structural Characterization of the New Clathrates K8Cd4Ge42, Rb8Cd4Ge42, and Cs8Cd4Ge42

    Directory of Open Access Journals (Sweden)

    Marion C. Schäfer

    2016-03-01

    Full Text Available This paper presents results from our exploratory work in the systems K-Cd-Ge, Rb-Cd-Ge, and Cs-Cd-Ge, which yielded the novel type-I clathrates with refined compositions K8Cd3.77(7Ge42.23, Rb8Cd3.65(7Ge42.35, and Cs7.80(1Cd3.65(6Ge42.35. The three compounds represent rare examples of clathrates of germanium with the alkali metals, where a d10 element substitutes a group 14 element. The three structures, established by single-crystal X-ray diffraction, indicate that the framework-building Ge atoms are randomly substituted by Cd atoms on only one of the three possible crystallographic sites. This and several other details of the crystal chemistry are elaborated.

  11. Interfacial processes in the Pd/a-Ge:H system

    Science.gov (United States)

    Edelman, F.; Cytermann, C.; Brener, R.; Eizenberg, M.; Weil, R.; Beyer, W.

    1993-06-01

    The kinetics of phase transformation has been studied in a two-layer structure of Pd/a-Ge:H after vacuum annealing at temperatures from 180 to 500°C. The a-Ge:H was deposited at 250°C on both c-Si and cleaved NaCl substrates in an RF glow discharge from a GeH 4/H 2 mixture. It was found that, similarly to the Pd/c-Ge and the Pd/a-Ge (e-gun deposited) systems, in the case of 0.15-0.2 μm Pd/0.6-1.0 μm a-Ge:H interfacial germanides formed first through the production of Pd 2Ge (plus a small amount of PdGe), and then PdGe was produced. The growth of both compounds was found to be diffusion-controlled. The nonreacted a-Ge:H layer beneath the germanide overlayer crystallized at 400-500°C. A reverse sequence of germanides formation was revealed in the case of 50 nm Pd/30 nm a-Ge:H, studied by in situ heat treatment in the TEM utilizing non-supported samples. The first germanide detected was PdGe and then, as a result of PdGe and Ge reaction or the PdGe decomposition, Pd 2Ge formed. The temperature dependence of the incubation time before the first ˜ 10 nm PdGe grains formed, followed an Arrhenius curve with an activation energy of 1.45 eV.

  12. (Si)GeSn nanostructures for light emitters

    Science.gov (United States)

    Rainko, D.; Stange, D.; von den Driesch, N.; Schulte-Braucks, C.; Mussler, G.; Ikonic, Z.; Hartmann, J. M.; Luysberg, M.; Mantl, S.; Grützmacher, D.; Buca, D.

    2016-05-01

    Energy-efficient integrated circuits for on-chip or chip-to-chip data transfer via photons could be tackled by monolithically grown group IV photonic devices. The major goal here is the realization of fully integrated group IV room temperature electrically driven lasers. An approach beyond the already demonstrated optically-pumped lasers would be the introduction of GeSn/(Si)Ge(Sn) heterostructures and exploitation of quantum mechanical effects by reducing the dimensionality, which affects the density of states. In this contribution we present epitaxial growth, processing and characterization of GeSn/(Si)Ge(Sn) heterostructures, ranging from GeSn/Ge multi quantum wells (MQWs) to GeSn quantum dots (QDs) embedded in a Ge matrix. Light emitting diodes (LEDs) were fabricated based on the MQW structure and structurally analyzed via TEM, XRD and RBS. Moreover, EL measurements were performed to investigate quantum confinement effects in the wells. The GeSn QDs were formed via Sn diffusion /segregation upon thermal annealing of GeSn single quantum wells (SQW) embedded in Ge layers. The evaluation of the experimental results is supported by band structure calculations of GeSn/(Si)Ge(Sn) heterostructures to investigate their applicability for photonic devices.

  13. Vertical self-organization of Ge1-xMnx nanocolumn multilayers grown on Ge(001) substrates

    Science.gov (United States)

    Le, Thi Giang; Dau, Minh Tuan

    2016-07-01

    High-resolution transmission electron microscopy (HR-TEM) has been used to investigate the structural properties of GeMn/Ge nanocolumns multilayer samples grown on Ge(001) substrates by means of molecular beam epitaxy (MBE) system. Four bilayers with the spacer thickness in the range between 6 nm and 15 nm and 10 periods of bilayers of Ge0.94Mn0.06/Ge nanocolumn are presented. A simplified 2D model based on the theory of elastic constant interactions has been used to provide reasonable explanations to the vertical self-organization of GeMn nanocolumns in multilayers.

  14. Thermal Expansion in YbGaGe

    OpenAIRE

    Bobev, Svilen; Williams, Darrick J.; Thompson, J.D.; Sarrao, J L

    2004-01-01

    Thermal expansion and magnetic susceptibility measurements as a function of temperature are reported for YbGaGe. Despite the fact that this material has been claimed to show zero thermal expansion over a wide temperature range, we observe thermal expansion typical of metals and Pauli paramagnetic behavior, which perhaps indicates strong sample dependence in this system.

  15. Analytical response function for planar Ge detectors

    Science.gov (United States)

    García-Alvarez, Juan A.; Maidana, Nora L.; Vanin, Vito R.; Fernández-Varea, José M.

    2016-04-01

    We model the response function (RF) of planar HPGe x-ray spectrometers for photon energies between around 10 keV and 100 keV. The RF is based on the proposal of Seltzer [1981. Nucl. Instrum. Methods 188, 133-151] and takes into account the full-energy absorption in the Ge active volume, the escape of Ge Kα and Kβ x-rays and the escape of photons after one Compton interaction. The relativistic impulse approximation is employed instead of the Klein-Nishina formula to describe incoherent photon scattering in the Ge crystal. We also incorporate a simple model for the continuous component of the spectrum produced by the escape of photo-electrons from the active volume. In our calculations we include external interaction contributions to the RF: (i) the incoherent scattering effects caused by the detector's Be window and (ii) the spectrum produced by photo-electrons emitted in the Ge dead layer that reach the active volume. The analytical RF model is compared with pulse-height spectra simulated using the PENELOPE Monte Carlo code.

  16. Platinum germanium ordering in UPtGe

    Science.gov (United States)

    Hoffmann, Rolf-Dieter; Pöttgen, Rainer; Lander, Gerry H.; Rebizant, Jean

    2001-09-01

    The non-centrosymmetric structure of UPtGe was investigated by X-ray diffraction on both powders and single crystals: EuAuGe type, Imm2, a=432.86(5), b=718.81(8), c=751.66(9) pm, wR2=0.0738 for 399 F2 values and 22 variables. The platinum and germanium atoms form two-dimensional layers of puckered Pt 3Ge 3 hexagons with short PtGe intralayer distances of 252 and 253 pm. These condensed two-dimensionally infinite nets are interconnected to each other via weak PtPt contacts with bond distances of 300 pm. The two crystallographically independent uranium atoms are situated above and below the six-membered platinum-germanium rings. The U1 atoms have six closer germanium neighbors while the U2 atoms have six closer platinum neighbors. The group-subgroup relation with the KHg 2 type structure is presented.

  17. Ge doping of FeGa3

    Science.gov (United States)

    Alvarez-Quiceno, J. C.; Cabrera-Baez, M.; Munévar, J.; Micklitz, H.; Bittar, E. M.; Baggio-Saitovitch, E.; Ribeiro, R. A.; Avila, M. A.; Dalpian, G. M.; Osorio-Guillén, J. M.

    2015-03-01

    The intermetallic narrow-gap semiconductor FeGa3 is one of the few Fe-based diamagnetic materials. Experimentally, Ge doping induces a ferromagnetic (FM) state. The mechanism responsible for this FM response is still unestablished, but there are proposals of itinerant magnetism to explain this behavior. Our DFT simulations show that inserting holes induces a delocalized FM response, while inserting electrons induces a localized FM response around some Fe atoms. We also modeled different distributions of Ge substitution and observe that the FM response depends on the Ge concentration and also on the Ge distribution on the Ga sites. We observed that the extra electrons become localized in some specific Fe atoms, rather than delocalized over the entire crystal lattice, as expected from an itinerant model. For experimental probing of this scenario, we have performed 57Fe Mössbauer spectroscopy on flux-grown singlecrystalline samples. The resulting resonance peak shape supports a localized model for ferromagnetism, since it is possible to resolve the presence of two distinct Fe isomer shifts (despite a single crystallographic site), expected to correspond to Fe atoms with high and low magnetic moments. The authors thank Capes, CNPQ and FAPESP for financial support.

  18. Parametrized dielectric functions of amorphous GeSn alloys

    Science.gov (United States)

    D'Costa, Vijay Richard; Wang, Wei; Schmidt, Daniel; Yeo, Yee-Chia

    2015-09-01

    We obtained the complex dielectric function of amorphous Ge1-xSnx (0 ≤ x ≤ 0.07) alloys using spectroscopic ellipsometry from 0.4 to 4.5 eV. Amorphous GeSn films were formed by room-temperature implantation of phosphorus into crystalline GeSn alloys grown by molecular beam epitaxy. The optical response of amorphous GeSn alloys is similar to amorphous Ge and can be parametrized using a Kramers-Kronig consistent Cody-Lorentz dispersion model. The parametric model was extended to account for the dielectric functions of amorphous Ge0.75Sn0.25 and Ge0.50Sn0.50 alloys from literature. The compositional dependence of band gap energy Eg and parameters associated with the Lorentzian oscillator have been determined. The behavior of these parameters with varying x can be understood in terms of the alloying effect of Sn on Ge.

  19. Dicalcium heptagermanate Ca(2)Ge(7)O(16) revised.

    Science.gov (United States)

    Redhammer, Günther J; Roth, Georg; Amthauer, Georg

    2007-07-01

    The structure of dicalcium heptagermanate, previously described with an orthorhombic space group, has been redetermined in the tetragonal space group P(overline4)b2. It contains three Ge positions (site symmetry 1, ..2 and 2.22, respectively), one Ca position (..2) and four O atoms, all on general 8i positions (site symmetry 1). A sheet of four-membered rings of Ge tetrahedra (with Ge on the 8i position) and isolated Ge tetrahedra (Ge on the 4g position) alternate with a sheet of Ge octahedra (Ge on the 2d position) and eightfold-coordinated Ca sites along the c direction in an ABABA... sequence. The three-dimensional framework of Ge sites displays a channel-like structure, evident in a projection on to the ab plane.

  20. Atomically flat Ge buffer layers and alternating shutter growth of CaGe2 for large area germanane

    Science.gov (United States)

    Xu, Jinsong; Katoch, Jyoti; Ahmed, Adam; Pinchuk, Igor; Williams, Robert; McComb, David; Kawakami, Roland

    Germanane (GeH), which is converted from CaGe2 by soaking in HCl acid, has recently attracted interest because of its novel properties, such as large band gap (1.56eV), spin orbit coupling and predictions of high mobility (18000 cm2/Vs). Previously CaGe2 was successfully grown on Ge(111) substrates by molecular beam epitaxy (MBE) growth. But there were cracks between µm-sized islands, which is not desirable for scientific study and application, and limits the material quality. By growing atomically flat Ge buffer layers and using alternating shutter MBE growth, we are able to grow crack-free, large area films of CaGe2 films. Reflection high energy electron diffraction (RHEED) patterns of Ge buffer layer and CaGe2 indicates high quality two dimensional surfaces, which is further confirmed by atomic force microscopy (AFM), showing atomically flat and uniform Ge buffer layer and CaGe2. The appearance of Laue oscillation in X-ray diffraction (XRD) and Kiessig fringes in X-ray reflectivity (XRR) proves the uniformity of CaGe2 film and the smoothness of the interface. The high quality of CaGe2 film makes it promising to explore novel properties of GeH. Funded by NSF MRSEC DMR-1420451.

  1. TEM characterization of Ge precipitates in an Al-1.6 at% Ge alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, K. [Department of Material Science and Engineering, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan)], E-mail: kaneko@zaiko.kyushu-u.ac.jp; Inoke, K. [FEI Company Japan Ltd., 13-34 Kohnan 2, Minato, Tokyo 108-0075 (Japan); Sato, K.; Kitawaki, K.; Higashida, H. [Department of Material Science and Engineering, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Arslan, I.; Midgley, P.A. [Department of Material Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)

    2008-02-15

    The growth mechanism and morphology of Ge precipitates in an Al-Ge alloy was characterized by a combination of in-situ transmission electron microscopy, high-resolution transmission electron microscopy and three-dimensional electron tomography. Anisotropic growth of rod-shaped Ge precipitates was observed by in-situ transmission electron microscopy over different time periods, and faceting of the precipitates was clearly seen using high-resolution transmission electron microscopy and three-dimensional electron tomography. This anisotropic growth of rod-shaped Ge precipitates was enhanced by vacancy concentration as proposed previously, but also by surface diffusion as observed during the in-situ experiment. Furthermore, a variety of precipitate morphologies was identified by three-dimensional electron tomography.

  2. Bi surfactant mediated growth for fabrication of Si/Ge nanostructures and investigation of Si/Ge intermixing by STM

    Energy Technology Data Exchange (ETDEWEB)

    Paul, N.

    2007-10-26

    In the thesis work presented here, we show that Bi is more promising surfactant material than Sb. We demonstrate that by using Bi as a terminating layer on Ge/Si surface, it is possible to distinguish between Si and Ge in Scanning tunnelling microscope (STM). Any attempt to utilize surfactant mediated growth must be preceded by a thorough study of its effect on the the system being investigated. Thus, the third chapter of this thesis deals with an extensive study of the Bi surfactant mediated growth of Ge on Si(111) surface as a function of Ge coverage. The growth is investigated from the single bilayer Ge coverage till the Ge coverage of about 15 BL when the further Ge deposition leads to two-dimensional growth. In the fourth chapter, the unique property of Bi terminating layer on Ge/Si surface to result in an STM height contrast between Si and Ge is explained with possible explanations given for the reason of this apparent height contrast. The controlled fabrication of Ge/Si nanostructures such as nanowires and nanorings is demonstrated. A study on Ge-Si diffusion in the surface layers by a direct method such as STM was impossible previously because of the similar electronic structure of Ge and Si. Since with the Bi terminating surface layer, one is able to distinguish between Ge and Si, the study of intermixing between them is also possible using STM. This method to distinguish between Si and Ge allows one to study intermixing on the nanoscale and to identify the fundamental diffusion processes giving rise to the intermixing. In Chapter 5 we discuss how this could prove useful especially as one could get a local probe over a very narrow Ge-Si interface. A new model is proposed to estimate change in the Ge concentration in the surface layer with time. The values of the activation energies of Ge/Si exchange and Si/Ge exchange are estimated by fitting the experimental data with the model. The Ge/Si intermixing has been studied on a surface having 1 ML Bi ({radical

  3. Fabrication and ferromagnetism of Si-SiGe/MnGe core-shell nanopillars

    Science.gov (United States)

    Wang, Liming; Liu, Tao; Wang, Shuguang; Zhong, Zhenyang; Jia, Quanjie; Jiang, Zuimin

    2016-10-01

    Si-Si0.5Ge0.5/Mn0.08Ge0.92 core-shell nanopillar samples were fabricated on ordered Si nanopillar patterned substrates by molecular beam epitaxy at low temperatures. The magnetic properties of the samples are found to depend heavily on the growth temperature of the MnGe layer. The sample grown at a moderate temperature of 300 °C has the highest Curie temperature of 240 K as well as the strongest ferromagnetic signals. On the basis of the microstructural results, the ferromagnetic properties of the samples are believed to come from the intrinsic Mn-doped amorphous or crystalline Ge ferromagnetic phase rather than any intermetallic ferromagnetic compounds of Mn and Ge. After being annealed at a temperature of 500 °C, all the samples exhibit the same Curie temperature of 220 K, which is in sharp contrast to the different Curie temperature for the as-grown samples, and the ferromagnetism for the annealed samples comes from Mn5GeSi2 compounds which are formed during the annealing.

  4. Doping and strain dependence of the electronic band structure in Ge and GeSn alloys

    Science.gov (United States)

    Xu, Chi; Gallagher, James; Senaratne, Charutha; Brown, Christopher; Fernando, Nalin; Zollner, Stefan; Kouvetakis, John; Menendez, Jose

    2015-03-01

    A systematic study of the effect of dopants and strain on the electronic structure of Ge and GeSn alloys is presented. Samples were grown by UHV-CVD on Ge-buffered Si using Ge3H8 and SnD4 as the sources of Ge and Sn, and B2H6/P(GeH3)3 as dopants. High-energy critical points in the joint-density of electronic states were studied using spectroscopic ellipsometry, which yields detailed information on the strain and doping dependence of the so-called E1, E1 +Δ1 , E0' and E2 transitions. The corresponding dependencies of the lowest direct band gap E0 and the fundamental indirect band gap Eindwere studied via room-T photoluminescence spectroscopy. Of particular interest for this work were the determination of deformation potentials, band gap renormalization effects, Burstein-Moss shifts due to the presence of carriers at band minima, and the dependence of other critical point parameters, such as amplitudes and phase angles, on the doping concentration. The selective blocking of transitions due to high doping makes it possible to investigate the precise k-space location of critical points. These studies are complemented with detailed band-structure calculations within a full-zone k-dot- p approach. Supported by AFOSR under DOD AFOSR FA9550-12-1-0208 and DOD AFOSR FA9550-13-1-0022.

  5. Reactivity of diaminogermylenes with ruthenium carbonyl: Ru3Ge3 and RuGe2 derivatives.

    Science.gov (United States)

    Cabeza, Javier A; García-Álvarez, Pablo; Polo, Diego

    2011-07-04

    The nature of the products of the reactions of [Ru(3)(CO)(12)] with diaminogermylenes depends upon the volume and the cyclic or acyclic structure of the latter. Thus, the triruthenium cluster [Ru(3){μ-Ge(NCH(2)CMe(3))(2)C(6)H(4)}(3)(CO)(9)], which has a planar Ru(3)Ge(3) core and an overall C(3h) symmetry, has been prepared in quantitative yield by treating [Ru(3)(CO)(12)] with an excess of the cyclic 1,3-bis(neo-pentyl)-2-germabenzimidazol-2-ylidene in toluene at 100 °C, but under analogous reaction conditions, the acyclic and bulkier Ge(HMDS)(2) (HMDS = N(SiMe(3))(2)) quantitatively leads to the mononuclear ruthenium(0) derivative [Ru{Ge(HMDS)(2)}(2)(CO)(3)]. Mixtures of products have been obtained from the reactions of [Ru(3)(CO)(12)] with the cyclic and very bulky 1,3-bis(tert-butyl)-2-germaimidazol-2-ylidene under various reaction conditions. The Ru(3)Ge(3) and RuGe(2) products reported in this paper are the first ruthenium complexes containing diaminogermylene ligands.

  6. High efficiency low cost GaAs/Ge cell technology

    Science.gov (United States)

    Ho, Frank

    1990-01-01

    Viewgraphs on high efficiency low cost GaAs/Ge cell technology are presented. Topics covered include: high efficiency, low cost GaAs/Ge solar cells; advantages of Ge; comparison of typical production cells for space applications; panel level comparisons; and solar cell technology trends.

  7. Electrical characterization of p-GeSn/n-Ge diodes with interface traps under dc and ac regimes

    Science.gov (United States)

    Baert, B.; Gupta, S.; Gencarelli, F.; Loo, R.; Simoen, E.; Nguyen, N. D.

    2015-08-01

    In this work, the electrical properties of p-GeSn/n-Ge diodes are investigated in order to assess the impact of defects at the interface between Ge and GeSn using temperature-dependent current-voltage and capacitance-voltage measurements. These structures are made from GeSn epitaxial layers grown by CVD on Ge with in situ doping by Boron. As results, an average ideality factor of 1.2 has been determined and an activation energy comprised between 0.28 eV and 0.30 eV has been extracted from the temperature dependence of the reverse-bias current. Based on the comparison with numerical results obtained from device simulations, we explain this activation energy by the presence of traps located near the GeSn/Ge interface.

  8. Theoretical prediction for several important equilibrium Ge isotope fractionation factors

    Science.gov (United States)

    Tang, M.; Li, X.; Liu, Y.

    2008-12-01

    As a newly emerging field, the stable isotope geochemistry of germanium (Ge) needs basic equilibrium fractionation factors to explore its unknown world. In this study, the Ge isotope fractionations between systems including the aqueous Ge(OH)4 and GeO(OH)3- which are the dominant Ge species in seawater, the Ge-bearing organic complexes (e.g. Ge-catechol, Ge-oxalic acid and Ge-citric acid), the quartz- (or opal- ), albite-, K-feldspar- and olivine- like mineral structures are studied. It is the first time that some geologically important equilibrium Ge isotope fractionation factors are reported. Surprisingly, up to 5 per mil large isotopic fractionations between these Ge isotope systems are found at 25 degree. These results suggest a potentially broad application for the Ge isotope geochemistry. Our theoretical calculations are based on the Urey model (or Bigeleisen-Mayer equation) and high level quantum chemistry calculations. The B3LYP/6-311+G(d,p) level quantum chemistry method and the explicit solvent model ("water droplet" method) are used. Many different conformers are also used for the aqueous complexes in order to reduce the possible errors coming from the differences of configurations in solution. The accuracy of our calculation of the Ge isotopic fractionations is estimated about 0.2 per mil. Our results show quartz-like or opal-like structure can enrich most heavy Ge isotopes. Relative to quartz (or opal), some Ge isotopic fractionations are (at 25 C): quartz-organic Ge = 4-5,quartz-Ge(OH)4 =0.9,quartz-GeO(OH)3- =1.5,quartz-albite=0.6,quartz-K-feldspar=0.4 and quartz-olivine=3.9 per mil. The large fractionations between inorganic Ge complexes and organic Ge ones could be used to distinguish the possible bio-involving processes. Our results suggest a good explanation to the experimental observations of Siebert et al. (2006) and Rouxel et al. (2006) and provide important constraints to the study of Ge cycle in ocean.

  9. Standard molar enthalpy of formation of FeGe(s) and FeGe{sub 2}(s) intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Phapale, S. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Mishra, R., E-mail: mishrar@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Chattaraj, D.; Samui, P. [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Sengupta, P. [Material Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Mishra, P.K. [Technical Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2014-04-05

    Highlights: • FeGe(s) and FeGe{sub 2}(s) have been synthesized and characterized. • The heat of dissolutions of Fe(s), Ge(s), FeGe(s) and FeGe2(s) in liquid tin have been measured. • Δ{sub f}H{sub 298}{sup °} of FeGe, FeGe{sub 2} were found to be to −15.56 ± 0.92 and −36.89 ± 1.17 kJ mol{sup −1}, respectively. -- Abstract: Thermodynamics plays an important role in predicting long term stability of the materials under different reactive conditions. The present paper describes determination of standard molar enthalpies of formation of FeGe(s) and FeGe{sub 2}(s) compounds employing a high temperature solution calorimeter. The reaction enthalpies of Fe(s), Ge(s), FeGe(s) and FeGe{sub 2}(s) in liquid Sn at 986 K were measured using a Calvet calorimeter. The standard molar enthalpy of formation of the compounds at 298 K (Δ{sub f}H{sub 298}{sup °}) were calculated using the measured reaction enthalpy data. The values of Δ{sub f}H{sub 298}{sup °} of FeGe(s) and FeGe{sub 2}(s) at 298 K were found to −15.56 ± 0.92 and −36.89 ± 1.17 kJ mol{sup −1}, respectively. The standard molar enthalpy of formation of FeGe(s) and FeGe{sub 2}(s) at 298 K obtained experimentally has been compared with the calculated values derived using Vienna ab initio simulation package (VASP)

  10. Structural Changes of Amorphous GeTe2 Films by Annealing (Formation of Metastable Crystalline GeTe2 Films)

    Science.gov (United States)

    Fukumoto, Hirofumi; Tsunetomo, Keiji; Imura, Takeshi; Osaka, Yukio

    1987-01-01

    Amorphous GeTe2 films with the thickness ˜0.5 μm, prepared by sputtering technique, transform into the crystalline GeTe2 films with the isomorphic structure to β-cristobalite, cubic SiO2, at Ta(annealing temperature){=}200°C. The cubic phase of GeTe2 is metastable and decomposes into the mixed crystal of GeTe and Te at Ta{=}250°C.

  11. Microstructural changes and fractal Ge nanocrystallites in polycrystalline Au/amorphous Ge thin bilayer films upon annealing

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z W; Lai, J K L; Shek, C H [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)

    2006-11-07

    Microstructural changes and fractal Ge nanocrystallites in polycrystalline Au/amorphous Ge thin bilayer films upon annealing have been investigated by scanning electron microscopy, transmission electron microscopy observations and x-ray energy-dispersive spectroscopy (EDS). Experimental results indicated that the microstructure of the metal Au film plays an important role in metal-induced crystallization for Au/Ge thin bilayer films upon annealing. Interestingly, we found the position exchange of Au and Ge films and the formation of the fractal Ge nanocrystallites induced by annealing. EDS microanalysis indicated that although there is lateral interdiffusion of Au and Ge atoms, the thickness of the fractal region and the matrix remain nearly the same. At the same time, EDS shows that there are also Au aggregates extending out of the films. It is suggested that, besides the preferred nucleation at the Au/Ge interface, the breaking of Ge-Ge bonds may stimulate the crystallization of amorphous Ge, so that the crystallization temperature of Au/Ge system is much lower than that of the isolated amorphous Ge system.

  12. Microstructural changes and fractal Ge nanocrystallites in polycrystalline Au/amorphous Ge thin bilayer films upon annealing

    Science.gov (United States)

    Chen, Z. W.; Lai, J. K. L.; Shek, C. H.

    2006-11-01

    Microstructural changes and fractal Ge nanocrystallites in polycrystalline Au/amorphous Ge thin bilayer films upon annealing have been investigated by scanning electron microscopy, transmission electron microscopy observations and x-ray energy-dispersive spectroscopy (EDS). Experimental results indicated that the microstructure of the metal Au film plays an important role in metal-induced crystallization for Au/Ge thin bilayer films upon annealing. Interestingly, we found the position exchange of Au and Ge films and the formation of the fractal Ge nanocrystallites induced by annealing. EDS microanalysis indicated that although there is lateral interdiffusion of Au and Ge atoms, the thickness of the fractal region and the matrix remain nearly the same. At the same time, EDS shows that there are also Au aggregates extending out of the films. It is suggested that, besides the preferred nucleation at the Au/Ge interface, the breaking of Ge-Ge bonds may stimulate the crystallization of amorphous Ge, so that the crystallization temperature of Au/Ge system is much lower than that of the isolated amorphous Ge system.

  13. Ternary and quaternary Ni(Si)Ge(Sn) contact formation for highly strained Ge p- and n-MOSFETs

    Science.gov (United States)

    Wirths, S.; Troitsch, R.; Mussler, G.; Hartmann, J.-M.; Zaumseil, P.; Schroeder, T.; Mantl, S.; Buca, D.

    2015-05-01

    The formation of new ternary NiGeSn and quaternary NiSiGeSn alloys has been investigated to fabricate metallic contacts on high Sn content, potentially direct bandgap group IV semiconductors. (Si)GeSn layers were pseudomorphically grown on Ge buffered Si(001) by reduced pressure chemical vapor deposition. Ni, i.e. the metal of choice for source/drain metallization in Si nanoelectronics, is employed for the stano-(silicon)-germanidation of highly strained (Si)GeSn alloys. We show that NiGeSn on GeSn layers change phase from well-oriented Ni5(GeSn)3 to poly-crystalline Ni1(GeSn)1 at very low annealing temperatures. A large range of GeSn compositions with Sn concentrations up to 12 at.%, and SiGeSn ternaries with large Si and Sn compositions from 18%/3% to 4%/11% are investigated. In addition, the sheet resistance, of importance for electronic or optoelectronic device contacts, is quantified. The incorporation of Si extends the thermal stability of the resulting low resistive quaternary phase compared to their NiGeSn counterparts.

  14. Photoreflectance Spectroscopy Characterization of Ge/Si0.16Ge0.84 Multiple Quantum Wells on Ge Virtual Substrate

    Directory of Open Access Journals (Sweden)

    Hung-Pin Hsu

    2013-01-01

    Full Text Available We report a detailed characterization of a Ge/Si0.16Ge0.84 multiple quantum well (MQW structure on Ge-on-Si virtual substrate (VS grown by ultrahigh vacuum chemical vapor deposition by using temperature-dependent photoreflectance (PR in the temperature range from 10 to 300 K. The PR spectra revealed a wide range of optical transitions from the MQW region as well as transitions corresponding to the light-hole and heavy-hole splitting energies of Ge-on-Si VS. A detailed comparison of PR spectral line shape fits and theoretical calculation led to the identification of various quantum-confined interband transitions. The temperature-dependent PR spectra of Ge/Si0.16Ge0.84 MQW were analyzed using Varshni and Bose-Einstein expressions. The parameters that describe the temperature variations of various quantum-confined interband transition energies were evaluated and discussed.

  15. ATLAS 750 GeV Analysis

    CERN Document Server

    Wang, Fuquan; The ATLAS collaboration

    2016-01-01

    These slides are for BEACH 2016 presentation about 750 GeV searches at the ATLAS experiment with the 3.2 $\\text{fb}^{-1}$ $\\sqrt{s}$=13 TeV data collected in year 2015. The results from $\\gamma\\gamma$ and $Z\\gamma$ final states are summarized. For $\\gamma\\gamma$ analysis, the local significance is 3.9 $\\sigma$ for the spin-0 selection and 3.8 $\\sigma$ for spin-2 selection at 750 GeV, with global significance both at 2.1 $\\sigma$. For the $Z\\gamma$ analysis, both the leptonic and hadronic decays of the $Z$ boson are studied and no excess at the signal region is observed.

  16. Booster 6-GeV study

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xi; Ankenbrandt, Charles M.; Pellico, William A.; Lackey, James; Padilla, Rene; /Fermilab; Norem, J.; /Argonne

    2004-12-01

    Since a wider aperture has been obtained along the Booster beam line, this opens the opportunity for Booster running a higher intensity beam than ever before. Sooner or later, the available RF accelerating voltage will become a new limit for the beam intensity. Either by increasing the RFSUM or by reducing the accelerating rate can achieve the similar goal. The motivation for the 6-GeV study is to gain the relative accelerating voltage via a slower acceleration.

  17. Heteroepitaxy of Ge-Si{sub 1{minus}x}Ge{sub x} superlattices on Si (100) substrates by GeH{sub 4}-Si MBE

    Energy Technology Data Exchange (ETDEWEB)

    Orlov, L.K.; Tolomasov, V.A.; Potapov, A.V.; Drozdov, Yu.N. [Russian Academy of Sciences, Nizhny Novgorod (Russian Federation). Inst. for Physics of Microstructures; Vdovin, V.I. [Inst. for Rare Metals Giredmet, Moscow (Russian Federation)

    1996-12-31

    The authors applied GeH{sub 4}-SI MBE for growing Ge-Si{sub 1{minus}x}Ge{sub x} superlattices on Si(100). They investigated the distribution and the structure of defects inside heteroepitaxial Si{sub 1{minus}x}Ge{sub x} layers grown on Si(100). It was shown that the system has unique peculiarities of a dislocation structure formation. They found out that the plastic deformation on a layer-substrate heteroboundary eliminates strong elastic deformation inside the grown layer.

  18. Amorphous inclusions during Ge and GeSn epitaxial growth via chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gencarelli, F., E-mail: federica.gencarelli@imec.be [imec, Kapeldreef 75, 3001 Leuven (Belgium); Dept. of Metallurgy and Materials Engineering, KU Leuven, B-3001 Leuven (Belgium); Shimura, Y. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Nuclear and Radiation Physics Section, KU Leuven, B-3001 Leuven (Belgium); Kumar, A. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Nuclear and Radiation Physics Section, KU Leuven, B-3001 Leuven (Belgium); Vincent, B.; Moussa, A.; Vanhaeren, D.; Richard, O.; Bender, H. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Vandervorst, W. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Nuclear and Radiation Physics Section, KU Leuven, B-3001 Leuven (Belgium); Caymax, M.; Loo, R. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Heyns, M. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Dept. of Metallurgy and Materials Engineering, KU Leuven, B-3001 Leuven (Belgium)

    2015-09-01

    In this work, we discuss the characteristics of particular island-type features with an amorphous core that are developed during the low temperature epitaxial growth of Ge and GeSn layers by means of chemical vapor deposition with Ge{sub 2}H{sub 6}. Although further investigations are needed to unambiguously identify the origin of these features, we suggest that they are originated by the formation of clusters of H and/or contaminants atoms during growth. These would initially cause the formation of pits with crystalline rough facets over them, resulting in ring-shaped islands. Then, when an excess surface energy is overcome, an amorphous phase would nucleate inside the pits and fill them. Reducing the pressure and/or increasing the growth temperature can be effective ways to prevent the formation of these features, likely due to a reduction of the surface passivation from H and/or contaminant atoms. - Highlights: • Island features with amorphous cores develop during low T Ge(Sn) CVD with Ge{sub 2}H{sub 6.} • These features are thoroughly characterized in order to understand their origin. • A model is proposed to describe the possible evolution of these features. • Lower pressures and/or higher temperatures avoid the formation of these features.

  19. Ternary germanides RERhGe2 (RE = Y, Gd-Ho) - New representatives of the YIrGe2 type

    Science.gov (United States)

    Voßwinkel, Daniel; Heletta, Lukas; Hoffmann, Rolf-Dieter; Pöttgen, Rainer

    2016-11-01

    The YIrGe2 type ternary germanides RERhGe2 (RE = Y, Gd-Ho) were synthesized from the elements by arc-melting and characterized by powder X-ray diffraction. The structure of DyRhGe2 was refined from single crystal X-ray diffractometer data: Immm, a = 426.49(9), b = 885.0(2), c = 1577.4(3) pm, wR2 = 0.0533, 637 F2 values, 30 variables (300 K data). The structure contains two crystallographically independent dysprosium atoms in pentagonal prismatic and hexagonal prismatic coordination. The three-dimensional [RhGe2] polyanion is stabilized through covalent Rh-Ge (243-261 pm) and Ge-Ge (245-251 pm) bonding. The close structural relationship with the slightly rhodium-poorer germanides RE5Rh4Ge10 (≡ RERh0.8Ge2) is discussed. Temperature-dependent magnetic susceptibility measurements reveal Pauli paramagnetism for YRhGe2 and Curie-Weiss paramagnetism for RERhGe2 with RE = Gd, Tb, Dy and Ho. These germanides order antiferromagnetically at TN = 7.2(5), 10.6(5), 8.1(5), and 6.4(5) K, respectively.

  20. Relaxed SiGe-on-insulator fabricated by dry oxidation of sandwiched Si/SiGe/Si structure

    Energy Technology Data Exchange (ETDEWEB)

    Di Zengfeng [Research Center of Semiconductor Functional Film Engineering Technology and State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Department of Physics and Material Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Zhang Miao [Research Center of Semiconductor Functional Film Engineering Technology and State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Liu Weili [Research Center of Semiconductor Functional Film Engineering Technology and State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Zhu Ming [Research Center of Semiconductor Functional Film Engineering Technology and State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Department of Physics and Material Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Lin Chenglu [Research Center of Semiconductor Functional Film Engineering Technology and State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Chu, Paul K. [Department of Physics and Material Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)]. E-mail: paul.chu@cityu.edu.hk

    2005-12-05

    An improved technique is demonstrated to fabricate silicon-germanium on insulator (SGOI) starting with a sandwiched structure of Si/SiGe/Si. After oxidation of the sandwiched structure and successive annealing, a relaxed SiGe-on-insulator (SGOI) structure is produced. Our results indicate that the added Si cap layer is advantageous in suppressing Ge loss at the initial stage of SiGe oxidation and the subsequent annealing process homogenizes the Ge fraction. Raman measurements reveal that the strain in the SiGe layer is fully relaxed at high oxidation temperature ({approx}1150 deg. C) without generating any threading dislocations and crosshatch patterns, which generally exist in the relaxed SiGe layer on bulk Si substrate.

  1. Fabrication of Multilevel Switching High Density Phase Change Data Recording Using Stacked GeTe/GeSbTe Structure

    Science.gov (United States)

    Hong, Sung-Hoon; Lee, Heon; Kim, Kang-In; Choi, Yunjung; Lee, Young-Kook

    2011-08-01

    The multilevel switching characteristics of stacked phase change materials with the structures of Ge2Sb2Te5, AgInSbTe/Ge2Sb2Te5, and GeTe/Ge2Sb2Te5 were investigated at the nano scale using nanoimprint lithography and conductive atomic force microscopy. Stacked phase change materials devices consisting of nano pillars 200 nm in diameter were fabricated using nanoimprint lithography, and their electrical characteristics were evaluated using conductive atomic force microscopy, with a pulse generator and a voltage source. The stacked GeTe/Ge2Sb2Te5 phase change materials exhibited three levels of resistance with a difference of 2 orders in magnitude between them, while the single-layer and stacked phase change materials with similar electrical resistances, such as Ge2Sb2Te5/AgInSbTe exhibited only bi level switching characteristics.

  2. Density and Capture Cross-Section of Interface Traps in GeSnO2 and GeO2 Grown on Heteroepitaxial GeSn.

    Science.gov (United States)

    Gupta, Somya; Simoen, Eddy; Loo, Roger; Madia, Oreste; Lin, Dennis; Merckling, Clement; Shimura, Yosuke; Conard, Thierry; Lauwaert, Johan; Vrielinck, Henk; Heyns, Marc

    2016-06-01

    An imperative factor in adapting GeSn as the channel material in CMOS technology, is the gate-oxide stack. The performance of GeSn transistors is degraded due to the high density of traps at the oxide-semiconductor interface. Several oxide-gate stacks have been pursued, and a midgap Dit obtained using the ac conductance method, is found in literature. However, a detailed signature of oxide traps like capture cross-section, donor/acceptor behavior and profile in the bandgap, is not yet available. We investigate the transition region between stoichiometric insulators and strained GeSn epitaxially grown on virtual Ge substrates. Al2O3 is used as high-κ oxide and either Ge1-xSnxO2 or GeO2 as interfacial layer oxide. The interface trap density (Dit) profile in the lower half of the bandgap is measured using deep level transient spectroscopy, and the importance of this technique for small bandgap materials like GeSn, is explained. Our results provide evidence for two conclusions. First, an interface traps density of 1.7 × 10(13) cm(-2)eV(-1) close to the valence band edge (Ev + 0.024 eV) and a capture cross-section (σp) of 1.7 × 10(-18) cm(2) is revealed for GeSnO2. These traps are associated with donor states. Second, it is shown that interfacial layer passivation of GeSn using GeO2 reduces the Dit by 1 order of magnitude (2.6 × 10(12) cm(-2)eV(-1)), in comparison to GeSnO2. The results are cross-verified using conductance method and saturation photovoltage technique. The Dit difference is associated with the presence of oxidized (Sn(4+)) and elemental Sn in the interfacial layer oxide.

  3. Electric and Magnetic Field Tunable Rectification and Magnetoresistance in FexGe1-x/Ge Heterojunction Diodes

    Institute of Scientific and Technical Information of China (English)

    QIN Yu-Feng; CHEN Yan-Xue; MEI Liang-Mo; ZHANG Ze; YAN Shi-Shen; KANG Shi-Shou; XIAO Shu-Qin; LI Qiang; DAI Zheng-Kun; SHEN Ting-Ting; DAI You-Yong; LIU Guo-Lei

    2011-01-01

    Fex Ge1- x/Ge amorphous heterojunction diodes with p-Fex Ge1-x ferromagnetic semiconductor layers are grown on single-crystal Ge substrates of p-type,n-type and intrinsic semiconductors,respectively.The I-V curves of pFe0.4 Ge0.6 /p-Ge diodes only show slight changes with temperature or with magnetic field.For the p-Fe0.4 Ge0.6 /nGe diode,good rectification is maintained at room temperature.More interestingly,the I-V curve of the pFe0.4Ge0.6/i-Ge diode can be tuned by the magnetic field,indicating a large positive magnetoresistance.The resistances of the junctions decrease with the increasing temperature,suggesting a typical semiconductor transport behavior.The origin of the positive magnetoresistance is discussed based on the effect of the electric and magnetic field on the energy band structures of the interface.In the past decades,ferromagnetic semiconductors (FMSs),which can be used as spin current sources,have received much attention due to their potential application in the next generation of information technology.In 1996,Ohno et a/.… reported molecular beam epitaxial (Ga,Mn)As FMSs,which show a wellaligned ferromagnetic order and an anomalous Halleffect.In 2002,Park et al.[2]%FexGe1-x/Ge amorphous heterojunction diodes with p-FexGe1-x ferromagnetic semiconductor layers are grown on single-crystal Ge substrates of p-type, n-type and intrinsic semiconductors, respectively. The I-V curves of p-Fe0.4Geo.6/p-Ge diodes only show slight changes with temperature or with magnetic field. For the p-Fe0.4Ge0.6/n-Ge diode, good rectification is maintained at room temperature. More interestingly, the I-V curve of the p-Fe0.4Ge0.6/I-Ge diode can be tuned by the magnetic field, indicating a large positive magnetoresistance. The resistances of the junctions decrease with the increasing temperature, suggesting a typical semiconductor transport behavior. The origin of the positive magnetoresistance is discussed based on the effect of the electric and magnetic field on the

  4. Formation of ζ phase in Cu-Ge peritectic alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Rapid growth behavior of ζ phase has been investigated in the undercooling experiments of Cu-14%Ge, Cu-15%Ge, Cu-18.5%Ge and Cu-22%Ge alloys. Alloys of the four compositions obtain the maximum undercoolings of 202 K(0.17TL), 245 K(0.20TL), 223 K(0.20TL) and 176 K(0.17TL), respectively. As the content of Ge increases, the microstructural transition of "α(Cu) dendrite + ζ peritectic phase → ζ peritectic phase → ζ dendrite + (ε+ζ ) eutectic" takes place in the alloy at small undercooling, while the microstructural transition of "fragmented α (Cu) dendrite +ζperitectic phase → ζ peritectic phase → ζ dendrite + ε phase" happens in the alloy at large undercooling. EDS analysis of the Ge content in ζ peritectic phase indicates that undercooling enlarges the solid solubility of α dendrite, which leads to a decrease in the Ge content in ζ phase as undercooling increases. In the Cu-18.5%Ge alloy composed of ζ peritectic phase, the Ge content in ζ phase increases when undercooling increases, which is due to the restraint of the Ge enrichment on the grain boundaries by high undercooling effect.

  5. Structural transformation of Ge dimers on Ge(001) surfaces induced by bias voltage

    Institute of Scientific and Technical Information of China (English)

    Qin Zhi-Hui; Shi Dong-Xia; Gao Hong-Jun

    2008-01-01

    Scanning tunnelling microscopy is utilized to investigate the local bias voltage tunnelling dependent transformation between (2×1) and c(4×2) structures on Ge(001) surfaces, which is reversibly observed at room temperature and a critical bias voltage of -0.80 V. Similar transformation is also found on an epitaxial Ge islands but at a slightly different critical bias voltage of -1.00V. It is found that the interaction between the topmost atoms on the STM tip and the atoms of the dimers, and the pinning effect induced by Sb atoms, the vacancies or the epitaxial clusters, can drive the structural transformation at the critical bias voltage.

  6. Walking from 750 GeV to 950 GeV in the technipion zoo

    Science.gov (United States)

    Matsuzaki, Shinya; Yamawaki, Koichi

    2016-06-01

    If the 750-GeV diphoton excess is identified with the color-singlet isosinglet technipion P0 (750) in the one-family walking technicolor model, as in our previous paper, then there should exist another color-singlet technipion-isotriplet one, P±,3, predicted at around 950 GeV independently of the dynamical details. The P±,3(950 ) are produced at the LHC via vector-boson and photon-fusion processes, predominantly decaying to W γ and γ γ , respectively. Those walking technicolor signals can be explored at run 2 or 3, which would further open the door for a plethora of other (colored) technipions.

  7. Design of Ge/SiGe quantum-confined Stark effect modulators for CMOS compatible photonics

    Science.gov (United States)

    Lever, Leon; Ikonić, Zoran; Valavanis, Alex; Kelsall, Robert W.

    2010-02-01

    A simulation technique for modeling optical absorption in Ge/SiGe multiple quantum well (MQW) heterostructures is described, based on a combined 6 × 6 k • p hole wave-function a one-band effective mass electron wavefunction calculation. Using this model, we employ strain engineering to target a specific applications-oriented wavelength, namely 1310 nm, and arrive at a design for a MQW structure to modulate light at this wavelength. The modal confinement in a proposed device is then found using finite-element modeling, and we estimate the performance of a proposed waveguide-integrated electroabsorption modulator.

  8. Electronic structure of Ge-2 and Ge-2 and thermodynamic properties of Ge-2 from all electron ab initio investigations and Knudsen effusion mass spectroscopic measurements

    DEFF Research Database (Denmark)

    Shim, Irene; Baba, M. Sai; Gingerich, K.A.

    2002-01-01

    excited states are presented. Thermal functions based on the theoretically determined molecular parameters were used to derive the thermodynamic properties of the Ge-2 molecule from new mass spectrometric equilibrium data. The literature value for the dissociation energy of Ge-2 has been re...

  9. Room Temperature Electroluminescence from Tensile-Strained Si0.13Ge0.87/Ge Multiple Quantum Wells on a Ge Virtual Substrate

    Directory of Open Access Journals (Sweden)

    Guangyang Lin

    2016-09-01

    Full Text Available Direct band electroluminescence (EL from tensile-strained Si0.13Ge0.87/Ge multiple quantum wells (MQWs on a Ge virtual substrate (VS at room temperature is reported herein. Due to the competitive result of quantum confinement Stark effect and bandgap narrowing induced by tensile strain in Ge wells, electroluminescence from Γ1-HH1 transition in 12-nm Ge wells was observed at around 1550 nm. As injection current density increases, additional emission shoulders from Γ2-HH2 transition in Ge wells and Ge VS appeared at around 1300–1400 nm and 1600–1700 nm, respectively. The peak energy of EL shifted to the lower energy side superquadratically with an increase of injection current density as a result of the Joule heating effect. During the elevation of environmental temperature, EL intensity increased due to a reduction of energy between L and Γ valleys of Ge. Empirical fitting of the relationship between the integrated intensity of EL (L and injection current density (J with L~Jm shows that the m factor increased with injection current density, suggesting higher light emitting efficiency of the diode at larger injection current densities, which can be attributed to larger carrier occupations in the Γ valley and the heavy hole (HH valance band at higher temperatures.

  10. Growth Mechanism and Surface Structure of Ge Nanocrystals Prepared by Thermal Annealing of Cosputtered GeSiO Ternary Precursor

    Directory of Open Access Journals (Sweden)

    Bo Zhang

    2014-01-01

    Full Text Available Ge nanocrystals (Ge-ncs embedded in a SiO2 superlattice structure were prepared by magnetron cosputtering and postdeposition annealing. The formation of spherical nanocrystals was confirmed by transmission electron microscopy and their growth process was studied by a combination of spectroscopic techniques. The crystallinity volume fraction of Ge component was found to increase with crystallite size, but its overall low values indicated a coexistence of crystalline and noncrystalline phases. A reduction of Ge-O species was observed in the superlattice during thermal annealing, accompanied by a transition from oxygen-deficient silicon oxide to silicon dioxide. A growth mechanism involving phase separation of Ge suboxides (GeOx was then proposed to explain these findings and supplement the existing growth models for Ge-ncs in SiO2 films. Further analysis of the bonding structure of Ge atoms suggested that Ge-ncs are likely to have a core-shell structure with an amorphous-like surface layer, which is composed of GeSiO ternary complex. The surface layer thickness was extracted to be a few angstroms and equivalent to several atomic layer thicknesses.

  11. Radiation-modified structure of Ge25Sb15S60 and Ge35Sb5S60 glasses.

    Science.gov (United States)

    Kavetskyy, T; Shpotyuk, O; Kaban, I; Hoyer, W

    2008-06-28

    Atomic structures of Ge(25)Sb(15)S(60) and Ge(35)Sb(5)S(60) glasses are investigated in the gamma-irradiated and annealed after gamma-irradiation states by means of high-energy synchrotron x-ray diffraction technique. The first sharp diffraction peak (FSDP) is detected at around 1.1 A(-1) in the structure factors of both alloys studied. The FSDP position is found to be stable for radiation/annealing treatment of the samples, while the FSDP intensity shows some changes between gamma-irradiated and annealed states. The peaks in the pair distribution functions observed between 2 and 4 A are related to the Ge-S, Ge-Sb, and Sb-Sb first neighbor correlations and Ge-Ge second neighbor correlations in the edge-shared GeS(42) tetrahedra, and S-S and/or Ge-Ge second neighbor correlations in the corner-shared GeS(42) tetrahedra. Three mechanisms of the radiation-/annealing-induced changes are discussed in the framework of coordination topological defect formation and bond-free solid angle concepts.

  12. Elasticity, Hardness and Thermal Conductivity of Si-Ge-Based Oxynitrides (SiGeN2O)

    Science.gov (United States)

    Ding, Yingchun; Chen, Min; Wu, Wenjuan; Xu, Ming

    2017-01-01

    Capitalizing on density functional theory, the novel Si-Ge-based oxynitrides (SiGeN2O) have been studied in terms of mechanical and thermal properties. Regarding α- or β-SiGeN2O, the SiGeN2O exhibits smaller mechanical moduli, suggesting a compressible and soft material. Our calculated lattice constants of two SiGeN2O phases are very consistent with other values. In addition, the hardness for SiGeN2O is investigated in details according to different semi-empirical methods. The results indicate a small hardness of two phases of SiGeN2O. Furthermore, the mechanical anisotropy, Debye temperature and the minimum thermal conductivity of two SiGeN2O compounds are clearly estimated for both SiGeN2O compounds. It is found that the SiGeN2O compounds show low thermal conductivity, which is suitable to be used as a thermal barrier coating.

  13. Elasticity, Hardness and Thermal Conductivity of Si-Ge-Based Oxynitrides (SiGeN2O)

    Science.gov (United States)

    Ding, Yingchun; Chen, Min; Wu, Wenjuan; Xu, Ming

    2016-09-01

    Capitalizing on density functional theory, the novel Si-Ge-based oxynitrides (SiGeN2O) have been studied in terms of mechanical and thermal properties. Regarding α- or β-SiGeN2O, the SiGeN2O exhibits smaller mechanical moduli, suggesting a compressible and soft material. Our calculated lattice constants of two SiGeN2O phases are very consistent with other values. In addition, the hardness for SiGeN2O is investigated in details according to different semi-empirical methods. The results indicate a small hardness of two phases of SiGeN2O. Furthermore, the mechanical anisotropy, Debye temperature and the minimum thermal conductivity of two SiGeN2O compounds are clearly estimated for both SiGeN2O compounds. It is found that the SiGeN2O compounds show low thermal conductivity, which is suitable to be used as a thermal barrier coating.

  14. Carbon Chains Containing Group IV Elements: Rotational Detection of GeC_4 and GeC_5

    Science.gov (United States)

    McCarthy, Michael C.; Martin-Drumel, Marie-Aline; Thorwirth, Sven

    2017-06-01

    Following the recent discovery of T-shaped GeC_2 by chirped-pulse FT microwave spectroscopy, evidence has been found for two longer carbon chains, GeC_4 and GeC_5, guided by high-level quantum chemical calculations of their molecular structure. Like their isovalent Si-bearing counterparts, those with an even number of carbon atoms are predicted to possess ^1Σ ground states, while odd-numbered carbon chains have low-lying ^3Σ linear isomers; all are predicted to be highly polar. With the exception of ^{73}Ge, rotational lines of the other four Ge isotopic species have been observed between 6 and 18 GHz. From these measurements, the Ge-C bond length has been determined to high precision, and can be compared to that found in other Ge species, such as GeC [1] and GeC_3Ge [2] studied previously at rotational resolution. Somewhat surprisingly, the spectrum of GeC_5 very closely resembles that of ^1Σ molecule, presumably owing to the very large spin-orbit constant of atomic Ge, which is manifest as an equally large spin-spin constant in the chain. A comparison between the production of SiC_n and GeC_n chains by laser ablation, including the absence of those with n=3, will be given. [1] C. R. Brazier and J. I. Ruiz, J. Mol. Spectrosc., 270, 26-32 (2011). [2] S. Thorwirth et al., J. Phys. Chem. A, 120, 254-259 (2016).

  15. High-pressure structural behavior of nanocrystalline Ge

    DEFF Research Database (Denmark)

    Wang, H.; Liu, J. F.; Yan, H.;

    2007-01-01

    The equation of state and the pressure of the I-II transition have been studied for nanocrystalline Ge using synchrotron x-ray diffraction. The bulk modulus and the transition pressure increase with decreasing particle size for both Ge-I and Ge-II, but the percentage volume collapse at the transi......The equation of state and the pressure of the I-II transition have been studied for nanocrystalline Ge using synchrotron x-ray diffraction. The bulk modulus and the transition pressure increase with decreasing particle size for both Ge-I and Ge-II, but the percentage volume collapse...... at the transition remains constant. Simplified models for the high-pressure structural behaviour are presented, based on the assumption that a large fraction of the atoms reside in grain boundary regions of the nanocrystalline material. The interface structure plays a significant role in affecting the transition...

  16. SiGe HBTs Optimization for Wireless Power Amplifier Applications

    Directory of Open Access Journals (Sweden)

    Pierre-Marie Mans

    2010-01-01

    Full Text Available This paper deals with SiGe HBTs optimization for power amplifier applications dedicated to wireless communications. In this work, we investigate the fT-BVCEO tradeoff by various collector optimization schemes such as epilayer thickness and dopant concentration, and SIC and CAP characteristics. Furthermore, a new trapezoidal base Germanium (Ge profile is proposed. Thanks to this profile, precise control of Ge content at the metallurgical emitter-base junction is obtained. Gain stability is obtained for a wide range of temperatures through tuning the emitter-base junction Ge percent. Finally, a comprehensive investigation of Ge introduction into the collector (backside Ge profile is conducted in order to improve the fT values at high injection levels.

  17. Nanoscale electrical properties of epitaxial Cu3Ge film

    Science.gov (United States)

    Wu, Fan; Cai, Wei; Gao, Jia; Loo, Yueh-Lin; Yao, Nan

    2016-07-01

    Cu3Ge has been pursued as next-generation interconnection/contact material due to its high thermal stability, low bulk resistivity and diffusion barrier property. Improvements in electrical performance and structure of Cu3Ge have attracted great attention in the past decades. Despite the remarkable progress in Cu3Ge fabrication on various substrates by different deposition methods, polycrystalline films with excess Ge were frequently obtained. Moreover, the characterization of nanoscale electrical properties remains challenging. Here we show the fabrication of epitaxial Cu3Ge thin film and its nanoscale electrical properties, which are directly correlated with localized film microstructures and supported by HRTEM observations. The average resistivity and work function of epitaxial Cu3Ge thin film are measured to be 6 ± 1 μΩ cm and ~4.47 ± 0.02 eV respectively, qualifying it as a good alternative to Cu.

  18. Nanoscale electrical properties of epitaxial Cu3Ge film

    Science.gov (United States)

    Wu, Fan; Cai, Wei; Gao, Jia; Loo, Yueh-Lin; Yao, Nan

    2016-01-01

    Cu3Ge has been pursued as next-generation interconnection/contact material due to its high thermal stability, low bulk resistivity and diffusion barrier property. Improvements in electrical performance and structure of Cu3Ge have attracted great attention in the past decades. Despite the remarkable progress in Cu3Ge fabrication on various substrates by different deposition methods, polycrystalline films with excess Ge were frequently obtained. Moreover, the characterization of nanoscale electrical properties remains challenging. Here we show the fabrication of epitaxial Cu3Ge thin film and its nanoscale electrical properties, which are directly correlated with localized film microstructures and supported by HRTEM observations. The average resistivity and work function of epitaxial Cu3Ge thin film are measured to be 6 ± 1 μΩ cm and ~4.47 ± 0.02 eV respectively, qualifying it as a good alternative to Cu. PMID:27363582

  19. Phase segregation in Pb:GeSbTe chalcogenide system

    Science.gov (United States)

    Kumar, J.; Ahmad, M.; Chander, R.; Thangaraj, R.; Sathiaraj, T. S.

    2008-01-01

    Effect of Pb substitution on the amorphous-crystalline transformation temperature, optical band gap and crystalline structure of Ge{2}Sb{2}Te{5} has been studied. In Pb:GeSbTe chalcogenide films prepared by thermal evaporation, an amorphous to crystallization transition is observed at 124, 129, 136 and 138 °C in Pb{0}Ge{20}Sb{24}Te{56}, Pb{1.6}Ge{19}Sb{26}Te{54}, Pb{3}Ge{17}Sb{28}Te{53} and Pb{5}Ge{12}Sb{28}Te{55} respectively. XRD investigations of annealed samples reveal that Pb substitution retains NaCl type crystalline structure of GST but expands the lattice due to large atomic radii. The increase in amorphous-crystalline transformation temperature is followed with the increase in phase segregation. The optical gap shows marginal variations with composition.

  20. Impacts of plasma-induced damage due to UV light irradiation during etching on Ge fin fabrication and device performance of Ge fin field-effect transistors

    Science.gov (United States)

    Mizubayashi, Wataru; Noda, Shuichi; Ishikawa, Yuki; Nishi, Takashi; Kikuchi, Akio; Ota, Hiroyuki; Su, Ping-Hsun; Li, Yiming; Samukawa, Seiji; Endo, Kazuhiko

    2017-02-01

    We investigated the impacts of plasma-induced damage due to UV light irradiation during etching on Ge fin fabrication and the device performance of Ge fin field-effect transistors (Ge FinFETs). UV light irradiation during etching affected the shape of the Ge fin and the surface roughness of the Ge fin sidewall. A vertical and smooth Ge fin could be fabricated by neutral beam etching without UV light irradiation. The performances of Ge FinFETs fabricated by neutral beam etching were markedly improved as compared to those of Ge FinFETs fabricated by inductively coupled plasma etching, in which the UV light has an impact.

  1. 500 GeV ILC Operating Scenarios

    CERN Document Server

    Brau, James E; Barklow, T; Brau, J; Fujii, K; Gao, J; List, J; Walker, N; Yokoya, K

    2015-01-01

    The ILC Technical Design Report documents the design of a 500 GeV linear collider, but does not specify the center-of-mass energy steps of operation for the collider. The ILC Parameters Joint Working Group has studied possible running scenarios, including a realistic estimate of the real time accumulation of integrated luminosity based on ramp-up and upgrade processes, and considered the evolution of the physics outcomes. These physics goals include Higgs precision measurements, top quark measurements and searches for new physics. We present an "optimized" operating scenario and the anticipated evolution of the precision of the ILC measurements.

  2. Commissioning and Operation of 12 GeV CEBAF

    Energy Technology Data Exchange (ETDEWEB)

    Freyberger, Arne P. [Jefferson Lab., Newport News, VA (United States)

    2015-09-01

    The Continuous Electron Beam Accelerator Facility (CEBAF) located at the Thomas Jefferson National Accelerator Laboratory (JLab) has been recently upgraded to deliver continuous electron beams to the experimental users at a maximum energy of 12 GeV, three times the original design energy of 4 GeV. This paper will present an overview of the upgrade, referred to as the 12GeV upgrade, and highlights from recent beam commissioning results.

  3. Optical phonons in Ge quantum dots obtained on Si(111)

    CERN Document Server

    Talochkin, A B

    2002-01-01

    The light combination scattering on the optical phonons in the Ge quantum dots, obtained on the Si surface of the (111) orientation through the molecular-beam epitaxy, is studied. The series of lines, connected with the phonon spectrum quantization, was observed. It is shown, that the phonon modes frequencies are well described by the elastic properties and dispersion of the voluminous Ge optical phonons. The value of the Ge quantum dots deformation is determined

  4. The Proposed Majorana 76Ge Double-Beta Decay Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Aalseth, Craig E; Anderson, Dale N; Arthur, Richard J; Avignone, Frank; Baktash, Cryus; Ball, Thedore; Barabash, Alexander S; Bertrand, F; Brodzinski, Ronald L; Brudanin, V; Bugg, William; Champagne, A E; Chan, Yuen-Dat; Cianciolo, Thomas V; Collar, J I; Creswick, R W; Descovich, M; Di Marco, Marie; Doe, P J; Dunham, Glen C; Efremenko, Yuri; Egerov, V; Ejiri, H; Elliott, Steven R; Emanuel, A; Fallon, Paul; Farach, H A; Gaitskell, R J; Gehman, Victor; Grzywacz, Robert; Hallin, A; Hazma, R; Henning, R; Hime, Andrew; Hossbach, Todd W; Jordan, David V; Kazkaz, K; Kephart, Jeremy; King, G S; Kochetov, Oleg; Konovalov, S; Kouzes, Richard T; Lesko, Kevin; Luke, P; Luzum, M; Macchiavelli, A O; McDonald, A; Mei, Dongming; Miley, Harry S; Mills, G B; Mokhtarani, A; Nomachi, Masaharu; Orrell, John L; Palms, John M; Poon, Alan; Radford, D C; Reeves, James H; Robertson, R G. H.; Runkle, Robert C; Rykaczewski, Krzysztof P; Saburov, Konstantin; Sandukovsky, Viatcheslav; Sonnenschein, Andrew; Tornow, W; Tull, C; van de Water, R G; Vanushin, Igor; Vetter, Kai; Warner, Ray A; Wilkerson, John F; Wouters, Jan M; Young, A R; Yumatov, V

    2005-01-01

    The proposed Majorana experiment is based on an array of segmented intrinsic Ge detectors with a total mass of 500 kg of Ge isotopically enriched to 86% in 76Ge. Background reduction will be accomplished by: material selection, detector segmentation, pulse shape analysis, electro-formation of copper parts, and granularity of detector spacing. The predicted experimental sensitivity for measurement of the neutrinoless double-beta decay mode of 76Ge, over a data acquisition period of 5000 kg•y, is ~ 4 x 1027 y.

  5. Growth of Ge films by cluster beam deposition

    CERN Document Server

    Xu, J L; Feng, J Y

    2002-01-01

    Ge epitaxial layers with reasonable quality were grown on the Si(1 1 1) substrates by cluster beam deposition (CBD) process. The growth temperature plays a dominant role in the epitaxial growth of Ge films. The substrate temperature for epitaxial growth is about 500 deg. C, which is lower than the reported critical temperature of Ge epitaxial growth by MBE and CVD. A stress induced phase transition of Ge lattice from cubic to tetragonal is also observed in the CBD process, and the mechanism is discussed.

  6. Impacts of excimer laser annealing on Ge epilayer on Si

    Science.gov (United States)

    Huang, Zhiwei; Mao, Yichen; Yi, Xiaohui; Lin, Guangyang; Li, Cheng; Chen, Songyan; Huang, Wei; Wang, Jianyuan

    2017-02-01

    The impacts of excimer laser annealing on the crystallinity of Ge epilayers on Si substrate grown by low- and high-temperature two-step approach in an ultra-high vacuum chemical vapor deposition system were investigated. The samples were treated by excimer laser annealing (ELA) at various laser power densities with the temperature above the melting point of Ge, while below that of Si, resulting in effective reduction of point defects and dislocations in the Ge layer with smooth surface. The full-width at half-maximum (FWHM) of X-ray diffraction patterns of the low-temperature Ge epilayer decreases with the increase in laser power density, indicating the crystalline improvement and negligible effect of Ge-Si intermixing during ELA processes. The short laser pulse time and large cooling rate cause quick melting and recrystallization of Ge epilayer on Si in the non-thermal equilibrium process, rendering tensile strain in Ge epilayer as calculated quantitatively with thermal mismatch between Si and Ge. The FWHM of X-ray diffraction patterns is significantly reduced for the two-step grown samples after treated by a combination of ELA and conventional furnace thermal annealing, indicating that the crystalline of Ge epilayer is improved more effectively with pre- annealing by excimer laser.

  7. On the macroscopic formation length for GeV photons

    CERN Document Server

    Thomsen, H D; Kirsebom, K; Knudsen, H; Uggerhøj, E; Uggerhøj1, U I; Sona, P; Mangiarotti, A; Ketel, T J; Dizdar, A; Dalton, M M; Ballestrero, S; Connell, S H

    2009-01-01

    Experimental results for the radiative energy loss of 206 and 234 GeV electrons in 5–10 μm thin Ta targets are presented. An increase in radiation emission probability at low photon energies compared to a 100 μm thick target is observed. This increase is due to the formation length of the GeV photons exceeding the thickness of the thin foils, the so-called Ternovskii–Shul'ga–Fomin (TSF) effect. The formation length of GeV photons from a multi-hundred GeV projectile is through the TSF effect shown directly to be a factor 1010 longer than their wavelength.

  8. Non-Selective SiGe Graphic Epitaxial by MBE

    Institute of Scientific and Technical Information of China (English)

    Qian Zhou; Chun Han; Jing-Chun Li

    2007-01-01

    To handle the thermal budget in SiGe BiCMOS process, a nonselective graphic epitaxial technology using molecular beam epitaxial (MBE) has been developed. SEM, AFM, XRD, and dislocation density measurements are carried out. The SiGe film's RMS roughness is 0.45nm, and dislocation density is 0.3×103cm2~1.2×103cm2. No dislocation accumulation exists on the boundary of the windows; this indicates the high quality of the SiGe film. The experiment results show that the technology presented in this paper meets the fabrication requirements of SiGe BiCMOS.

  9. Formation of extended defects in SiGe/Si heterostructures with SiGeC intermediate layers

    Energy Technology Data Exchange (ETDEWEB)

    Vdovin, V.I.; Reznik, V.Ya. [Institute for Chemical Problems of Microelectronics, Moscow (Russian Federation); Torack, T.A.; Fei, Lu [MEMC Inc, St Peters, MO (United States); Mil' vidskii, M.G. [Institute of Rare Metals ' Giredmet' , Moscow (Russian Federation); Falster, R. [MEMC Electronic Materials SpA, Novara (Italy)

    2007-07-01

    The generation of misfit dislocations (MDs) and stacking faults (SFs) was studied by TEM and preferential chemical etching in multilayer Si(001)/SiGe/SiGeC(10 nm)/SiGe/Si heterostructures grown by CVD at 650 C. Prior to growth of Si layer, the other part of heterostructure was annealed at 950 C in the growth chamber to get relaxed buffer layers and strained Si layer free of extended defects. We used SiGe alloys with Ge content of 24 at.% and C content of 0.5 at.%. Carbon in the strained SiGe matrix was found to promote high rates of strain relaxation through the nucleation of perfect dislocation loops close to the interface with Si substrate. For Si layer thickness >10 nm, threading dislocations split in these layers under tensile strain to form SFs. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Investigation of Ge1-xSnx/Ge with high Sn composition grown at low-temperature

    Directory of Open Access Journals (Sweden)

    I. S. Yu

    2011-12-01

    Full Text Available We report on experimental investigations of the growth of Ge1-xSnx film with thickness above the critical thickness using Molecular Beam Epitaxy. A series of Ge1-xSnx films with various Sn compositions up to 14% are deposited on a Ge buffer layer for growth at low temperatures close to the melting point of Sn. Analysis of various measurements shows that the Ge1-xSnx film is defect free in the XTEM image and that Sn is distributed almost uniformly in the film for Sn compositions up to 9.3%. The Sn composition of the films is higher than the Sn composition that is theoretically predicted to cause the energy band of Ge to change from an indirect to a direct bandgap; thus, the present investigation provides a method for growing direct bandgap GeSn film, which is desired for use in applications involving optoelectronic devices.

  11. GeSn p-i-n photodetectors with GeSn layer grown by magnetron sputtering epitaxy

    Science.gov (United States)

    Zheng, Jun; Wang, Suyuan; Liu, Zhi; Cong, Hui; Xue, Chunlai; Li, Chuanbo; Zuo, Yuhua; Cheng, Buwen; Wang, Qiming

    2016-01-01

    We report an investigation of normal-incidence GeSn-based p-i-n photodetectors (PDs) with a Ge0.94Sn0.06 active layer grown using sputter epitaxy on a Ge(100) substrate. A low dark current density of 0.24 A/cm2 was obtained at a reverse bias of 1 V. A high optical responsivity of the Ge0.94Sn0.06/Ge p-i-n PDs at zero bias was achieved, with an optical response wavelength extending to 1985 nm. The temperature-dependent optical-response measurement was performed, and a clear redshift absorption edge was observed. This work presents an approach for developing efficient and cost-effective GeSn-based infrared devices.

  12. Gamma bandgap determination in pseudomorphic GeSn layers grown on Ge with up to 15% Sn content

    Science.gov (United States)

    Gassenq, A.; Milord, L.; Aubin, J.; Guilloy, K.; Tardif, S.; Pauc, N.; Rothman, J.; Chelnokov, A.; Hartmann, J. M.; Reboud, V.; Calvo, V.

    2016-12-01

    Adding Tin (Sn) to Germanium (Ge) can turn it into a direct bandgap group IV semiconductor emitting in the mid-infrared wavelength range. Several approaches are currently being investigated to improve the GeSn devices. It has been theoretically predicted that the strain can improve their optical properties. However, the impact of strain on band parameters has not yet been measured for really high Sn contents (i.e., above 11%). In this work, we have used the photocurrent and photoluminescence spectroscopy to measure the gamma bandgap in compressively strained GeSn layers grown on Ge buffers. A good agreement is found with the modeling and the literature. We show here that the conventional GeSn deformation potentials used in the literature for smaller Sn contents can be applied up to 15% Sn. This gives a better understanding of strained-GeSn for future laser designs.

  13. In-situ Ga doping of fully strained Ge1-xSnx heteroepitaxial layers grown on Ge(001) substrates

    DEFF Research Database (Denmark)

    Shimura, Y.; Takeuchi, S.; Nakatsuka, O.;

    2012-01-01

    to the introduction of dislocations, due to the increase in the strain of the Ge1-xSnx layers. We achieved the growth of a fully strained Ge0.922Sn0.078 layer on Ge with a Ga concentration of 5.5×1019 /cm3 without any dislocations and stacking faults. The resistivity of the Ga-doped Ge1-xSnx layer decreased as the Sn...... content was increased. This decrease was due to an increase in the carrier concentration, with an increase in the activation level of Ga atoms in the Ge1-xSnx epitaxial layers being induced by the introduction of Sn. As a result, we found that the resistivity for the Ge0.950Sn0.050 layer annealed at 600°C...

  14. Magneto-transport properties of MnGeP2 and MnGeAs2 films

    Directory of Open Access Journals (Sweden)

    Yunki Kim

    2016-12-01

    Full Text Available MnGeAs2 and MnGeP2 thin films were deposited on GaAs and Si substrates. For these film samples, roomtemperature ferromagnetism was observed from magnetization and resistance measurements and verified from hysteresis in magnetization measurements. Hysteresis as well as anomalous behavior in Hall effect measurements was found in the deposited MnGeAs2 and MnGeP2 films, implying spin polarization of the mobile carriers in the films. The Hall resistance measurements above the ferromagnetic transition temperature showed that the carriers are n-type in MnGeAs2 and p-type in MnGeP2.

  15. Structural and phonon transmission study of Ge-Au-Ge eutectically bonded interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Knowlton, W.B. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley Lab., CA (United States). Materials Sciences Div.

    1995-07-01

    This thesis presents a structural analysis and phonon transparency investigation of the Ge-Au-Ge eutectic bond interface. Interface development was intended to maximize the interfacial ballistic phonon transparency to enhance the detection of the dark matter candidate WIMPs. The process which was developed provides an interface which produces minimal stress, low amounts of impurities, and insures Ge lattice continuity through the interface. For initial Au thicknesses of greater than 1,000 {angstrom} Au per substrate side, eutectic epitaxial growth resulted in a Au dendritic structure with 95% cross sectional and 90% planar Au interfacial area coverages. In sections in which Ge bridged the interface, lattice continuity across the interface was apparent. Epitaxial solidification of the eutectic interface with initial Au thicknesses < 500 A per substrate side produced Au agglomerations thereby reducing the Au planar interfacial area coverage to as little as 30%. The mechanism for Au coalescence was attributed to lateral diffusion of Ge and Au in the liquid phase during solidification. Phonon transmission studies were performed on eutectic interfaces with initial Au thicknesses of 1,000 {angstrom}, 500 {angstrom}, and 300 {angstrom} per substrate side. Phonon imaging of eutectically bonded samples with initial Au thicknesses of 300 {angstrom}/side revealed reproducible interfacial percent phonon transmissions from 60% to 70%. Line scan phonon imaging verified the results. Phonon propagation TOF spectra distinctly showed the predominant phonon propagation mode was ballistic. This was substantiated by phonon focusing effects apparent in the phonon imaging data. The degree of interface transparency to phonons and resulting phonon propagation modes correlate with the structure of the interface following eutectic solidification. Structural studies of samples with initial Au thickness of 1,000 {angstrom}/side appear to correspond with the phonon transmission study.

  16. Multi-GeV Electron Spectrometer

    CERN Document Server

    Faccini, R; Bacci, A; Batani, D; Bellaveglia, M; Benocci, R; Benedetti, C; Cacciotti, L; Cecchetti, C A; Clozza, A; Cultrera, L; Di~Pirro, G; Drenska, N; Anelli, F; Ferrario, M; Filippetto, D; Fioravanti, S; Gallo, A; Gamucci, A; Gatti, G; Ghigo, A; Giulietti, A; Giulietti, D; Gizzi, L A; Koester, P; Labate, L; Levato, T; Lollo, V; Londrillo, P; Martellotti, S; Pace, E; Patack, N; Rossi, A; Tani, F; Serafini, L; Turchetti, G; Vaccarezza, C; Valente, P

    2010-01-01

    The advance in laser plasma acceleration techniques pushes the regime of the resulting accelerated particles to higher energies and intensities. In particular the upcoming experiments with the FLAME laser at LNF will enter the GeV regime with almost 1pC of electrons. From the current status of understanding of the acceleration mechanism, relatively large angular and energy spreads are expected. There is therefore the need to develop a device capable to measure the energy of electrons over three orders of magnitude (few MeV to few GeV) under still unknown angular divergences. Within the PlasmonX experiment at LNF a spectrometer is being constructed to perform these measurements. It is made of an electro-magnet and a screen made of scintillating fibers for the measurement of the trajectories of the particles. The large range of operation, the huge number of particles and the need to focus the divergence present unprecedented challenges in the design and construction of such a device. We will present the design ...

  17. A 100 GeV SLAC Linac

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Zoltan D

    2002-03-07

    The SLAC beam energy can be increased from the current 50 GeV to 100 GeV, if we change the operating frequency from the present 2856 MHz to 11424 MHz, using technology developed for the NLC. We replace the power distribution system with a proposed NLC distribution system as shown in Fig. 1. The four 3 meter s-band 820 nS fill time accelerator sections are replaced by six 2 meter x-band 120 nS fill time sections. Thus the accelerator length per klystron retains the same length, 12 meters. The 4050 65MW-3.5 {micro}S klystrons are replaced by 75MW-1.5 {micro}S permanent magnet klystrons developed here and in Japan. The present input to the klystrons would be multiplied by a factor of 4 and possibly amplified. The SLED [1] cavities have to be replaced. The increase in beam voltage is due to the higher elastance to group velocity ratio, higher compression ratio and higher unloaded to external Q ratio of the new SLED cavities. The average power input is reduced because of the narrower klystron pulse width and because the klystron electro-magnets are replaced by permanent magnets.

  18. Towards simultaneous achievement of carrier activation and crystallinity in Ge and GeSn with heated phosphorus ion implantation: An optical study

    Science.gov (United States)

    D'Costa, Vijay Richard; Wang, Lanxiang; Wang, Wei; Lim, Sin Leng; Chan, Taw Kuei; Chua, Lye Hing; Henry, Todd; Zou, Wei; Hatem, Christopher; Osipowicz, Thomas; Tok, Eng Soon; Yeo, Yee-Chia

    2014-09-01

    We have investigated the optical properties of Ge and GeSn alloys implanted with phosphorus ions at 400 °C by spectroscopic ellipsometry from far-infrared to ultraviolet. The dielectric response of heated GeSn implants displays structural and transport properties similar to those of heated Ge implants. The far-infrared dielectric function of as-implanted Ge and GeSn shows the typical free carrier response which can be described by a single Drude oscillator. Bulk Ge-like critical points E1, E1 + Δ1, E0', and E2 are observed in the visible-UV dielectric function of heated Ge and GeSn indicating single crystalline quality of the as-implanted layers. Although the implantation at 400 °C recovers crystallinity in both Ge and GeSn, an annealing step is necessary to enhance the carrier activation.

  19. Strong room temperature electroluminescence from lateral p-SiGe/i-Ge/n-SiGe heterojunction diodes on silicon-on-insulator substrate

    Science.gov (United States)

    Lin, Guangyang; Yi, Xiaohui; Li, Cheng; Chen, Ningli; Zhang, Lu; Chen, Songyan; Huang, Wei; Wang, Jianyuan; Xiong, Xihuan; Sun, Jiaming

    2016-10-01

    A lateral p-Si0.05Ge0.95/i-Ge/n-Si0.05Ge0.95 heterojunction light emitting diode on a silicon-on-insulator (SOI) substrate was proposed, which is profitable to achieve higher luminous extraction compared to vertical junctions. Due to the high carrier injection ratio of heterostructures and optical reflection at the SiO2/Si interface of the SOI, strong room temperature electroluminescence (EL) at around 1600 nm from the direct bandgap of i-Ge with 0.30% tensile strain was observed. The EL peak intensity of the lateral heterojunction is enhanced by ˜4 folds with a larger peak energy than that of the vertical Ge p-i-n homojunction, suggesting that the light emitting efficiency of the lateral heterojunction is effectively improved. The EL peak intensity of the lateral heterojunction, which increases quadratically with injection current density, becomes stronger for diodes with a wider i-Ge region. The CMOS compatible fabrication process of the lateral heterojunctions paves the way for the integration of the light source with the Ge metal-oxide-semiconductor field-effect-transistor.

  20. Magnetic and electrical properties of epitaxial GeMn

    Energy Technology Data Exchange (ETDEWEB)

    Ahlers, Stefan

    2009-01-15

    In this work, GeMn magnetic semiconductors will be investigated. The fabrication of GeMn thin films with Mn contents up to 11.7% was realised with molecular beam epitaxy. At a fabrication temperature of 60 C, the suppression of Mn{sub x}Ge{sub y} phases could reproducibly be obtained. Dislocation free epitaxy of diamond-lattice type GeMn thin films was observed. In all fabrication conditions where Mn{sub x}Ge{sub y} suppression was feasible, an inhomogeneous dispersion of Mn was observed in form of a self-assembly of nanometre sized, Mn rich regions in a Ge rich matrix. Each Mn rich region exhibits ferromagnetic coupling with high Curie temperatures exceeding, in part, room temperature. The local ferromagnetic ordering leads to the formation of large, spatially separated magnetic moments, which induce a superparamagnetic behaviour of the GeMn thin films. At low temperatures {<=} 20 K, remanent behaviour was found to emerge. X-ray absorption experiments revealed a similarity of the Mn incorporation in diamond-lattice type GeMn thin films and in the hexagonal lattice of the intermetallic Mn{sub 5}Ge{sub 3} phase, respectively. These tetrahedra represent building blocks of the Mn{sub 5}Ge{sub 3} unit cell. The incorporation of Mn{sub 5}Ge{sub 3} building blocks was found to be accompanied by local structural disorder. The electrical properties of GeMn thin films were addressed by transport measurements. It was shown that by using a n-type Ge substrate, a pn energy barrier between epilayers and substrate to suppress parallel substrate conduction paths can be introduced. With the pn barrier concept, first results on the magnetotransport behaviour of GeMn thin films were obtained. GeMn was found to be p-type, but of high resistivity. a series of GeMn thin films was fabricated, where intermetallic Mn{sub x}Ge{sub y} phase separation was supported in a controlled manner. Phase separation was found to result in the formation of partially coherent, nanometre sized Mn{sub 5

  1. Fabrication of GeSn-multiple quantum wells by overgrowth of Sn on Ge by using molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, F. [Institute for Semiconductor Engineering, University of Stuttgart, 70569 Stuttgart (Germany); Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Fischer, I. A.; Schulze, J. [Institute for Semiconductor Engineering, University of Stuttgart, 70569 Stuttgart (Germany); Benedetti, A. [CACTI, Univ. de Vigo, Campus Universitario Lagoas Marcosende 15, Vigo (Spain); Zaumseil, P. [IHP GmbH, Innovations for High Performance Microelectronics, Leibniz-Institut für innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Cerqueira, M. F.; Vasilevskiy, M. I. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Stefanov, S.; Chiussi, S. [Dpto. Fisica Aplicada, Univ. de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain)

    2015-12-28

    We report on the fabrication and structural characterization of epitaxially grown ultra-thin layers of Sn on Ge virtual substrates (Si buffer layer overgrown by a 50 nm thick Ge epilayer followed by an annealing step). Samples with 1 to 5 monolayers of Sn on Ge virtual substrates were grown using solid source molecular beam epitaxy and characterized by atomic force microscopy. We determined the critical thickness at which the transition from two-dimensional to three-dimensional growth occurs. This transition is due to the large lattice mismatch between Ge and Sn (≈14.7%). By depositing Ge on top of Sn layers, which have thicknesses at or just below the critical thickness, we were able to fabricate ultra-narrow GeSn multi-quantum-well structures that are fully embedded in Ge. We report results on samples with one and ten GeSn wells separated by 5 and 10 nm thick Ge spacer layers that were characterized by high resolution transmission electron microscopy and X-ray diffraction. We discuss the structure and material intermixing observed in the samples.

  2. Room-temperature direct-bandgap photoluminescence from strain-compensated Ge/SiGe multiplequantum wells on silicon

    Institute of Scientific and Technical Information of China (English)

    Hu Wei-Xuan; Cheng Bu-Wen; Xue Chun-Lai; Zhang Guang-Ze; Su Shao-Jian; Zuo Yu-Hua; Wang Qi-Ming

    2012-01-01

    Strain-compensated Ge/Si0.15Ge0.s5 multiple quantum wells were grown on an Si0.1Ge0.9 virtual substrate using ultrahigh vacuum chemical vapor deposition technology on an n+-Si(001) substrate.Photoluminescence measurements were performed at room temperature,and the quantum confinement effect of the direct-bandgap transitions of a Ge quantum well was observed,which is in good agreement with the calculated results.The luminescence mechanism was discussed by recombination rate analysis and the temperature dependence of the luminescence spectrum.

  3. Low temperature growth of heavy boron-doped hydrogenated Ge epilayers and its application in Ge/Si photodetectors

    Science.gov (United States)

    Kuo, Wei-Cheng; Lee, Ming Jay; Wu, Mount-Learn; Lee, Chien-Chieh; Tsao, I.-Yu; Chang, Jenq-Yang

    2017-04-01

    In this study, heavily boron-doped hydrogenated Ge epilayers are grown on Si substrates at a low growth temperature (220 °C). The quality of the boron-doped epilayers is dependent on the hydrogen flow rate. The optical emission spectroscopic, X-ray diffraction and Hall measurement results demonstrate that better quality boron-doped Ge epilayers can be obtained at low hydrogen flow rates (0 sccm). This reduction in quality is due to an excess of hydrogen in the source gas, which breaks one of the Ge-Ge bonds on the Ge surface, leading to the formation of unnecessary dangling bonds. The structure of the boron doped Ge epilayers is analyzed by transmission electron microscopy and atomic force microscopy. In addition, the performance, based on the I-V characteristics, of Ge/Si photodetectors fabricated with boron doped Ge epilayers produced under different hydrogen flow rates was examined. The photodetectors with boron doped Ge epilayers produced with a low hydrogen flow rate (0 sccm) exhibited a higher responsivity of 0.144 A/W and a lower dark current of 5.33 × 10-7 A at a reverse bias of 1 V.

  4. Solid state synthesis of Mn5Ge3 in Ge/Ag/Mn trilayers: Structural and magnetic studies

    Science.gov (United States)

    Myagkov, V. G.; Bykova, L. E.; Matsynin, A. A.; Volochaev, M. N.; Zhigalov, V. S.; Tambasov, I. A.; Mikhlin, Yu L.; Velikanov, D. A.; Bondarenko, G. N.

    2017-02-01

    The thin-film solid-state reaction between elemental Ge and Mn across chemically inert Ag layers with thicknesses of (0, 0.3, 1 and 2.2 μm) in Ge/Ag/Mn trilayers was studied for the first time. The initial samples were annealed at temperatures between 50 and 500 °C at 50 °C intervals for 1 h. The initiation temperature of the reaction for Ge/Mn (without a Ag barrier layer) was 120 °C and increased slightly up to 250 °C when the Ag barrier layer thickness increased up to 2.2 μm. In spite of the Ag layer, only the ferromagnetic Mn5Ge3 compound and the Nowotny phase were observed in the initial stage of the reaction after annealing at 500 °C. The cross-sectional studies show that during Mn5Ge3 formation the Ge is the sole diffusing species. The magnetic and cross-sectional transmission electron microscopy (TEM) studies show an almost complete transfer of Ge atoms from the Ge film, via a 2.2 μm Ag barrier layer, into the Mn layer. We attribute the driving force of the long-range transfer to the long-range chemical interactions between reacting Mn and Ge atoms.

  5. Photoconductivity of ultra-thin Ge(GeSn) layers grown in Si by low-temperature molecular beam epitaxy

    Science.gov (United States)

    Talochkin, A. B.; Chistokhin, I. B.; Mashanov, V. I.

    2016-04-01

    Photoconductivity (PC) spectra of Si/Ge(GeSn)/Si structures with the ultra-thin (1.0-2.3 nm) Ge and GeSn alloy layers grown by the low-temperature (T = 100 °C) molecular beam epitaxy are studied. Photoresponse in the range of 1.2-0.4 eV related to light absorption in the buried Ge(GeSn) layer is observed. It is shown that in case of lateral PC, a simple diffusion model can be used to determine the absorption coefficient of this layer α ˜ 105 cm-1. This value is 100 times larger than that of a single Ge quantum dot layer and is reached significantly above the band gap of most bulk semiconductors. The observed absorption is caused by optical transitions between electron and hole states localized at the interfaces. The anomalous high value of α can be explained by the unusual state of Ge(GeSn) layer with high concentration of dangling bonds, the optical properties of which have been predicted theoretically by Knief and von Niessen (Phys. Rev. B 59, 12940 (1999)).

  6. Fabrication of GeSn-multiple quantum wells by overgrowth of Sn on Ge by using molecular beam epitaxy

    Science.gov (United States)

    Oliveira, F.; Fischer, I. A.; Benedetti, A.; Zaumseil, P.; Cerqueira, M. F.; Vasilevskiy, M. I.; Stefanov, S.; Chiussi, S.; Schulze, J.

    2015-12-01

    We report on the fabrication and structural characterization of epitaxially grown ultra-thin layers of Sn on Ge virtual substrates (Si buffer layer overgrown by a 50 nm thick Ge epilayer followed by an annealing step). Samples with 1 to 5 monolayers of Sn on Ge virtual substrates were grown using solid source molecular beam epitaxy and characterized by atomic force microscopy. We determined the critical thickness at which the transition from two-dimensional to three-dimensional growth occurs. This transition is due to the large lattice mismatch between Ge and Sn (≈14.7%). By depositing Ge on top of Sn layers, which have thicknesses at or just below the critical thickness, we were able to fabricate ultra-narrow GeSn multi-quantum-well structures that are fully embedded in Ge. We report results on samples with one and ten GeSn wells separated by 5 and 10 nm thick Ge spacer layers that were characterized by high resolution transmission electron microscopy and X-ray diffraction. We discuss the structure and material intermixing observed in the samples.

  7. Ge/SiGe quantum confined Stark effect electro-absorption modulation with low voltage swing at λ = 1550 nm.

    Science.gov (United States)

    Dumas, D C S; Gallacher, K; Rhead, S; Myronov, M; Leadley, D R; Paul, D J

    2014-08-11

    Low-voltage swing (≤1.0 V) high-contrast ratio (6 dB) electro-absorption modulation covering 1460 to 1560 nm wavelength has been demonstrated using Ge/SiGe quantum confined Stark effect (QCSE) diodes grown on a silicon substrate. The heterolayers for the devices were designed using an 8-band k.p Poisson-Schrödinger solver which demonstrated excellent agreement with the experimental results. Modelling and experimental results demonstrate that by changing the quantum well width of the device, low power Ge/SiGe QCSE modulators can be designed to cover the S- and C-telecommunications bands.

  8. Li-Ge-H system: Hydrogenation and structural properties of LiGeHx (0

    Science.gov (United States)

    Pavlyuk, V.; Ciesielski, W.; Kulawik, D.; Prochwicz, W.; Rożdżyńska-Kiełbik, B.

    2016-11-01

    The synthesis, isothermal section at 450 °C of the Li-Ge-H system in the concentration region from 40 at.% Li to 70 at.% Li and structural characterizations of the observed phases are reported. The hydrogenation and structural properties of the LiGeHx (0 < x < 0.25) phase were studied by volumetric analysis and X-ray diffraction. The absorption of hydrogen by LiGe binary compound produce the ternary hydride phase LiGeHx (0 < x < 0.25), thus the volume tetragonal unit cell increases on 1.8 Å3. The LiGeHx solid solution is formed by means of the insertion of hydrogen atoms into tetrahedral voids of parent LiGe structure. The extension of homogeneity range of LiGeHx (0 < x < 0.25) phase and its crystal structure were more precisely refined using X-ray diffraction data. Electronic structure calculations reveal an increased occupation of electronic states at the Fermi level for LiGeHx in comparison to LiGe.

  9. Structural and optical properties of GaAs-based heterostructures with Ge and Ge/InGaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Aleshkin, V. Ya.; Dubinov, A. A., E-mail: sanya@ipm.sci-nnov.ru; Drozdov, M. N. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Zvonkov, B. N. [Nizhni Novgorod State University, Research Physical Technical Institute (Russian Federation); Kudryavtsev, K. E.; Tonkikh, A. A.; Yablonskiy, A. N. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Werner, P. [Max Planck Institute of Microstructure Physics (Germany)

    2013-05-15

    GaAs-based heterostructures with Ge and Ge/InGaAs quantum wells are grown by laser-assisted sputtering. Structural and optical studies of the heterostructures are carried out. A broad photoluminescence line is observed in the wavelength range from 1300 to 1650 nm. The line corresponds to indirect transitions in the momentum space of the Ge quantum wells and to transitions between the In{sub 0.28}Ga{sub 0.72}As and Ge layers, indirect in coordinate space, but direct in momentum space.

  10. Early effect of SiGe heterojunction bipolar transistors

    Science.gov (United States)

    Xu, Xiao-Bo; Zhang, He-Ming; Hu, Hui-Yong; Qu, Jiang-Tao

    2012-06-01

    The standard Early voltage of the SGP model is generalized for SiGe NPN heterojunction bipolar transistors (HBTs). A new compact formulation of the Early voltage compatible with the SGP model is presented. The impact of the Ge profile on Early effect is shown and validated by experiments. The model can be applied to the SGP model for circuit simulation.

  11. GeGI (Germanium Gamma Imager) Performance: Maritime Interdiction Operation

    Energy Technology Data Exchange (ETDEWEB)

    Dreyer, Jonathan G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Burks, Morgan T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Trombino, Dave [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-09-23

    The Gamma Ray Imager (GeGI) was demonstrated during the Maritime Interdiction Operation at Point Alameda, the site of the former Naval Air Station, in Alameda, CA. During this exercise GeGI was used to localize sources within an abandoned building and a cargo ship, the Admiral Callaghan.

  12. Parametrized dielectric functions of amorphous GeSn alloys

    Energy Technology Data Exchange (ETDEWEB)

    D' Costa, Vijay Richard, E-mail: elevrd@nus.edu.sg; Wang, Wei; Yeo, Yee-Chia, E-mail: eleyeoyc@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore); Schmidt, Daniel [Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603 (Singapore)

    2015-09-28

    We obtained the complex dielectric function of amorphous Ge{sub 1−x}Sn{sub x} (0 ≤ x ≤ 0.07) alloys using spectroscopic ellipsometry from 0.4 to 4.5 eV. Amorphous GeSn films were formed by room-temperature implantation of phosphorus into crystalline GeSn alloys grown by molecular beam epitaxy. The optical response of amorphous GeSn alloys is similar to amorphous Ge and can be parametrized using a Kramers-Kronig consistent Cody-Lorentz dispersion model. The parametric model was extended to account for the dielectric functions of amorphous Ge{sub 0.75}Sn{sub 0.25} and Ge{sub 0.50}Sn{sub 0.50} alloys from literature. The compositional dependence of band gap energy E{sub g} and parameters associated with the Lorentzian oscillator have been determined. The behavior of these parameters with varying x can be understood in terms of the alloying effect of Sn on Ge.

  13. Synthesis of Ge nanocrystals embedded in a Si host matrix

    Science.gov (United States)

    Ngiam, Shih-Tung; Jensen, Klavs F.; Kolenbrander, K. D.

    1994-12-01

    The synthesis of a composite material consisting of Ge nanoclusters (greater than or equal to 2 nm in diameter) embedded in a Si host matrix is reported. The Ge nanoparticles are produced by pulsed laser ablation and are codeposited in a Si film simultaneously grown by chemical beam epitaxy using disilane. Scanning transmission electron microscopy, combined with energy-dispersive x-ray measurements, show that discrete Ge particles (greater than or equal to 2 nm diameter) are deposited within a polycrystalline Si host matrix. High-resolution transmission electron microscopy reveals that the paricles are crystalline with a lattice spacing corresponding to that of Ge. The enhancement of Si deposition rates from silanes in the presence of Ge, previously demonstrated in chemical vapor deposition of Si(1 - x)Ge(x) alloys, is shown to facilitate the growth of a Si layer around the Ge nanocrystals. The overall composition of the Ge cluster/Si host composite material is determined by Rutherford backscattering measurements.

  14. Replacement of Ge in GeTe by [Ag +Sb] and rare earths: effect on thermoelectric properties

    Science.gov (United States)

    Levin, E. M.; Hanson, M.; Hanus, R.; Schmidt-Rohr, K.

    2013-03-01

    High-efficiency p-type Te-Sb-Ge-Ag (TAGS) thermoelectric materials are based on the GeTe narrow-band self-dopant semiconductor where Ge can be replaced by up to 16 at.% [Ag +Sb]. To understand the effect of Ge replacement by 4 at.% [Ag +Sb] as well as rare earths atoms, we have synthesized and studied XRD, thermopower, electrical resistivity, thermal conductivity, and 125Te NMR of GeTe and Ag2Sb2Ge46-xRxTe50 with R =Gd, Dy and x = 1, 2. At 700 K, GeTe exhibits a thermopower of +146 μVK-1 and a large power factor, 42 μWcm-1K-2. Replacement of Ge by [Ag +Sb] and rare earths enhances the thermopower, but slightly reduces the power factor due to an increase in electrical resistivity. The thermal conductivity at 300 K of all alloys studied is reduced by a factor of two compared to GeTe. 125Te NMR spin-lattice relaxation time and resonance frequency reflect changes in carrier concentration. However, decrease of thermal conductivity due to carriers and increase of electrical resistivity are mostly due to a reduction of carrier mobility and indicate strong scattering produced by [Ag +Sb] and rare earth atoms. At 700 K, the thermoelectric figure of merit of GeTe is 0.8, whereas that in Ag2Sb2Ge45Dy1Te50 is much larger, 1.2, due to a reduction in thermal conductivity. Enhancement of thermopower is discussed within a model of energy filtering.

  15. Undoped and in-situ B doped GeSn epitaxial growth on Ge by atmospheric pressure-chemical vapor deposition

    DEFF Research Database (Denmark)

    Vincent, B.; Gencarelli, F.; Bender, H.

    2011-01-01

    In this letter, we propose an atmospheric pressure-chemical vapor deposition technique to grow metastable GeSn epitaxial layers on Ge. We report the growth of defect free fully strained undoped and in-situ B doped GeSn layers on Ge substrates with Sit contents up to 8%. Those metastable layers stay...

  16. 3 GeV Injector Design Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Wiedemann, H.; /SLAC, SSRL

    2009-12-16

    This Design Handbook is intended to be the main reference book for the specifications of the 3 GeV SPEAR booster synchrotron project. It is intended to be a consistent description of the project including design criteria, key technical specifications as well as current design approaches. Since a project is not complete till it's complete changes and modifications of early conceptual designs must be expected during the duration of the construction. Therefore, this Design Handbook is issued as a loose leaf binder so that individual sections can be replaced as needed. Each page will be dated to ease identification with respect to latest revisions. At the end of the project this Design Handbook will have become the 'as built' reference book of the injector for operations and maintenance personnel.

  17. Phase diagram of UCoGe

    Science.gov (United States)

    Mineev, V. P.

    2017-03-01

    The temperature-pressure phase diagram of ferromagnetic superconductor UCoGe includes four phase transitions. They are between the paramagnetic and the ferromagnetic states with the subsequent transition in the superconducting ferromagnetic state and between the normal and the superconducting states after which the transition to the superconducting ferromagnetic state has to occur. Here we have developed the Landau theory description of the phase diagram and established the specific ordering arising at each type of transition. The phase transitions to the ferromagnetic superconducting state are inevitably accompanied by the emergence of screening currents. The corresponding magnetostatics considerations allow for establishing the significant difference between the transition from the ferromagnetic to the ferromagnetic superconducting state and the transition from the superconducting to the ferromagnetic superconducting state.

  18. CW SRF Electron Linac for Nuclear Physics Research: CEBAF 4 GeV, 6 GeV, and 12 GeV

    CERN Document Server

    Reece, Charles E

    2016-01-01

    CEBAF, the Continuous Electron Beam Accelerator Facility, has been actively serving the nuclear physics research community as a unique forefront international resource since 1995. This CW electron linear accelerator (linac) at the U.S. Department of Energy's Thomas Jefferson National Accelerator Facility (Jefferson Lab) has continued to evolve as a precision tool for discerning the structure and dynamics within nuclei. Superconducting RF (SRF) technology has been the essential foundation for CEBAF, first as a 4 GeV machine, then 6 GeV, and currently capable of 12 GeV. We review the development, implementation, and performance of SRF systems for CEBAF from its early beginnings to the commissioning of the 12 GeV era.

  19. GeNF - experimental report 2003

    Energy Technology Data Exchange (ETDEWEB)

    Schreyer, A.; Vollbrandt, J.; Willumeit, R. (eds.) [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. for Materials Research

    2004-07-01

    At the Geesthacht Neutron Facility GeNF about 210 experiments were performed in 2003 by GKSS and by or for external users, partners or contractors. In most cases the measurements were performed and analysed in cooperation by the guest and by the GKSS staff or by the permanent external user group staff. The activities, which are based on a proposal procedure and on the in house R and D program, are reported in 76 contributions in the present annual experimental report for the year 2003. The contributions may contain one or also several combined experiments. During 2003 the GKSS research reactor FRG-1 achieved an operation time of 252 days at the full 5 MW reactor power providing a neutron flux of ca. 1,4 x 10{sup 14} thermal neutrons / cm{sup 2} s. The cold neutron source was available during the complete operation time. The focus of the in house R and D work at GeNF instruments was the characterisation of metal alloys, the analysis of stresses in welds and technical structures at ARES, FSS, DCD and SANS-2, the structural investigation of hydrogen containing substances such as polymers, colloids and biological macromolecules at SANS-1 as well as the characterisation of magnetic thin films at PNR and ROeDI. The reflectomer TOREMA was thoroughly upgraded to the instrument NeRo and now offers new measurement possibilities. In the appendices the progress of the project REFSANS at FRM-II is reported as well as the experimental activities of the newly installed GKSS outstation HARWI-II at DESY. (orig.)

  20. GeNF - Experimental report 2006

    Energy Technology Data Exchange (ETDEWEB)

    Pranzas, P.K.; Schreyer, A.; Willumeit, R. (eds.) [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. of Materials Research

    2007-07-01

    At the Geesthacht Neutron Facility GeNF about 212 experiments were performed in 2006 by GKSS and by or for external users, partners or contractors. In most cases the measurements were performed and analysed in cooperation by the guests and by the GKSS staff or by the permanent external user group staff. The activities, which are based on a proposal procedure and on the in house R and D program, are reported in 71 contributions in the present annual experimental report for the year 2006. The contributions may contain one or also several combined experiments. During 2006 the GKSS research reactor FRG-1 achieved an operation time of 197 days at the full 5 MW reactor power providing a neutron flux of ca. 1.4 x 10{sup 14} thermal neutrons/cm{sup 2}s. The cold neutron source was available during the complete operation time. The focus of the in house R and D work at GeNF instruments was the characterisation of nanostructures in engineering materials, the analysis of stresses and textures in welds and technical structures at ARES-2, TEX-2, DCD and SANS-2, the structural investigation of hydrogen containing substances such as polymers, colloids and biological macromolecules at SANS-1 as well as the characterisation of magnetic thin films at PNR, NeRo, POLDI and ROeDI. The thoroughly upgraded residual stress diffractomer ARES-2 went in full operation in spring 2006 as well as the new neutron tomography device at GENRA-3. The installation of modern experiment control hardware and software based on LabView was completed on all designated instruments. In the appendices I and II the experimental reports of REFSANS at FRM II are attached as well as of the GKSS outstation HARWI-II at DESY. Both instruments started full operation in 2006. (orig.)

  1. Good NEWS for GeV Dark Matter Searches

    CERN Document Server

    Profumo, Stefano

    2015-01-01

    The proposed NEWS apparatus, a spherical detector with a small central electrode sensor operating as a proportional counter, promises to explore new swaths of the direct detection parameter space in the GeV and sub-GeV Dark Matter particle mass range by employing very light nuclear targets, such as H and He, and by taking advantage of a very low (sub-keV) energy threshold. Here we discuss and study two example classes of Dark Matter models that will be tested with NEWS: GeV-scale millicharged Dark Matter, and a GeV-Dirac Fermion Dark Matter model with a light (MeV-GeV) scalar or vector mediator, and indicate the physical regions of parameter space the experiment can probe.

  2. GeV dark matter searches with the NEWS detector

    Science.gov (United States)

    Profumo, Stefano

    2016-03-01

    The proposed NEWS apparatus, a spherical detector with a small central electrode sensor operating as a proportional counter, promises to explore new swaths of the direct detection parameter space in the GeV and sub-GeV dark matter particle mass range by employing very light nuclear targets, such as H and He, and by taking advantage of a very low (sub-keV) energy threshold. Here we discuss and study two example classes of dark matter models that will be tested with NEWS: GeV-scale millicharged dark matter, and a GeV-Dirac Fermion dark matter model with a light (MeV-GeV) scalar or vector mediator, and indicate the physical regions of parameter space the experiment can probe.

  3. Polarized Proton Collisions at 205GeV at RHIC

    Science.gov (United States)

    Bai, M.; Roser, T.; Ahrens, L.; Alekseev, I. G.; Alessi, J.; Beebe-Wang, J.; Blaskiewicz, M.; Bravar, A.; Brennan, J. M.; Bruno, D.; Bunce, G.; Courant, E.; Drees, A.; Fischer, W.; Gardner, C.; Gill, R.; Glenn, J.; Haeberli, W.; Huang, H.; Jinnouchi, O.; Kewisch, J.; Luccio, A.; Luo, Y.; Nakagawa, I.; Okada, H.; Pilat, F.; Mackay, W. W.; Makdisi, Y.; Montag, C.; Ptitsyn, V.; Satogata, T.; Stephenson, E.; Svirida, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Wise, T.; Zelenski, A.; Zeno, K.; Zhang, S. Y.

    2006-05-01

    The Brookhaven Relativistic Heavy Ion Collider (RHIC) has been providing collisions of polarized protons at a beam energy of 100 GeV since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during acceleration from injection to 100 GeV. However, the intrinsic spin resonances beyond 100 GeV are about a factor of 2 stronger than those below 100 GeV making it important to examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were first accelerated to the record energy of 205 GeV in RHIC with a significant polarization measured at top energy in 2005. This Letter presents the results and discusses the sensitivity of the polarization survival to orbit distortions.

  4. Carrier transport in Ge nanowires / Si substrate heterojunction

    Science.gov (United States)

    Lee, E.-K.; Kamenev, B.; Tsybeskov, L.; Sharma, S.; Kamins, T. I.

    2006-03-01

    Semiconductor nanowires (NWs) attached to lattice-mismatched single-crystal substrates form quasi-one-dimensional (QOD) heterojunctions (HJs) where efficient structural relaxation might occur due to high surface-to-volume ratio. Current-voltage characteristics in Ge NW/(p+)Si samples with nearly micron-long Ge NWs exhibit metal-type conductivity with ohmic behavior and little conductivity temperature dependence. In contrast, Ge NW/(n+)Si samples display significant change in conductivity as a function of temperature with an activation energy up to 200 meV. In a narrow temperature interval near 150 K we observed current instabilities and oscillations for Ge NW/(n+)Si. At higher temperatures we find negative differential photoconductivity at low forward biases. Our experimental results are explained using a model of nearly ideal Si substrate/Ge NW hetero-interfaces.

  5. First evidence of low energy enhancement in Ge isotopes

    Directory of Open Access Journals (Sweden)

    Renstrøm T.

    2015-01-01

    Full Text Available The γ-strength functions and level densities of 73,74Ge have been extracted from particle-γ coincidence data using the Oslo method. In addition the γ-strength function of 74Ge above the neutron separation threshold, Sn = 10.196 MeV has been extracted from photoneutron measurements. When combined, these two experiments give a γ-strength function covering the energy range of ∼1-13 MeV for 74Ge. This thorough investigation of 74Ge is a part of an international campaign to study the previously reported low energy enhancement in this mass region in the γ-strength function from ∼3MeV towards lower γ energies. The obtained data show that both 73,74Ge display an increase in strength at low γ energies.

  6. Plasmon-assisted photoresponse in Ge-coated bowtie nanojunctions

    CERN Document Server

    Evans, Kenneth M; Natelson, Douglas

    2016-01-01

    We demonstrate plasmon-enhanced photoconduction in Au bowtie nanojunctions containing nanogaps overlaid with an amorphous Ge film. The role of plasmons in the production of nanogap photocurrent is verified by studying the unusual polarization dependence of the photoresponse. With increasing Ge thickness, the nanogap polarization of the photoresponse rotates 90 degrees, indicating a change in the dominant relevant plasmon mode, from the resonant transverse plasmon at low thicknesses to the nonresonant "lightning rod" mode at higher thicknesses. To understand the plasmon response in the presence of the Ge overlayer and whether the Ge degrades the Au plasmonic properties, we investigate the photothermal response (from the temperature-dependent Au resistivity) in no-gap nanowire structures, as a function of Ge film thickness and nanowire geometry. The film thickness and geometry dependence are modeled using a cross-sectional, finite element simulation. The no-gap structures and the modeling confirm that the strik...

  7. Anisotropic Differential Reflectance Spectroscopy of Thin GeSe

    Science.gov (United States)

    Matson, Joseph; Woods, Grace; Churchill, Hugh

    2017-01-01

    Atomically thin monochalcogenides are predicted to exhibit a two-dimensional structural phase transition. This phase transition could be useful for designing new phase change memory devices. The critical temperature is dependent on the material as well as the thickness, and is predicted to occur just above room temperature for monolayer GeSe. We used differential reflectance spectroscopy on thin samples of GeSe to measure changes in the optical anisotropy with temperature as a signature of this phase transition. We constructed an apparatus for temperature-depedendent spectroscopy of micro-scale GeSe samples, and measured anisotropic optical absorption of thin GeSe. We observed a decrease in optical anisotropy of GeSe at elevated temperatures, which may be a first indication of the continuous transition from a rectangular to a square lattice in that material. This work was supported by NSF REU Grant #EEC-1359306.

  8. Barrier enhancement of Ge MSM IR photodetector with Ge layer optimization

    Science.gov (United States)

    Asar, Tarık; Özçelik, Süleyman

    2015-12-01

    Germanium thin films were deposited on n-type Silicon substrates with three different sputter power by using DC magnetron sputtering system at room temperature. The structural and morphological properties of the samples have been obtained by means of X-ray diffraction and atomic force microscopy measurements. Then, Germanium metal-semiconductor-metal infrared photodetectors were fabricated on these structures. The carrier recombination lifetime and the diffusion length of the devices were also calculated by using the carrier density and mobility data was obtained from the room temperature Hall Effect measurements. The dark current-voltage measurements of devices were achieved at room temperature. The electrical parameters such as ideality factor, Schottky barrier height, saturation current and series resistance were extracted from dark current-voltage characteristics. Finally, it has been shown that the barrier enhancement of Ge MSM IR photodetector can be achieved by Ge layer optimization.

  9. Walking from 750 GeV to 950 GeV in the Technipion Zoo

    CERN Document Server

    Matsuzaki, Shinya

    2016-01-01

    If the 750 GeV diphoton excess is identified with the color-singlet isosinglet-technipion, $P^0$ (750), in the one-family walking technicolor, as in our previous paper, then there should exist another color-singlet technipion, isotriplet one, $P^{\\pm,3}$, definitely predicted at around 950 GeV independently of the dynamical details. The $P^{\\pm,3}(950)$ are produced at the LHC via vector boson and photon fusion processes, predominantly decaying to $W \\gamma$, and $\\gamma\\gamma$, respectively. Those walking technicolor signals can be explored at the Run 2, or 3, which would further open a way to a plethora of yet other (colored) technipions.

  10. Effect of asymmetric concentration profile on thermal conductivity in Ge/SiGe superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, Konstanze R., E-mail: konstanze.hahn@dsf.unica.it [Department of Physics, University of Cagliari, Cittadella Universitaria, 09042 Monserrato (Italy); Cecchi, Stefano [Department of Epitaxy, Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany); Colombo, Luciano [Department of Physics, University of Cagliari, Cittadella Universitaria, 09042 Monserrato (Italy); Institut de Cieǹcia de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra, 08193 Barcelona (Spain); Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona (Spain)

    2016-05-16

    The effect of the chemical composition in Si/Ge-based superlattices on their thermal conductivity has been investigated using molecular dynamics simulations. Simulation cells of Ge/SiGe superlattices have been generated with different concentration profiles such that the Si concentration follows a step-like, a tooth-saw, a Gaussian, and a gamma-type function in direction of the heat flux. The step-like and tooth-saw profiles mimic ideally sharp interfaces, whereas Gaussian and gamma-type profiles are smooth functions imitating atomic diffusion at the interface as obtained experimentally. Symmetry effects have been investigated comparing the symmetric profiles of the step-like and the Gaussian function to the asymmetric profiles of the tooth-saw and the gamma-type function. At longer sample length and similar degree of interdiffusion, the thermal conductivity is found to be lower in asymmetric profiles. Furthermore, it is found that with smooth concentration profiles where atomic diffusion at the interface takes place the thermal conductivity is higher compared to systems with atomically sharp concentration profiles.

  11. Effect of asymmetric concentration profile on thermal conductivity in Ge/SiGe superlattices

    Science.gov (United States)

    Hahn, Konstanze R.; Cecchi, Stefano; Colombo, Luciano

    2016-05-01

    The effect of the chemical composition in Si/Ge-based superlattices on their thermal conductivity has been investigated using molecular dynamics simulations. Simulation cells of Ge/SiGe superlattices have been generated with different concentration profiles such that the Si concentration follows a step-like, a tooth-saw, a Gaussian, and a gamma-type function in direction of the heat flux. The step-like and tooth-saw profiles mimic ideally sharp interfaces, whereas Gaussian and gamma-type profiles are smooth functions imitating atomic diffusion at the interface as obtained experimentally. Symmetry effects have been investigated comparing the symmetric profiles of the step-like and the Gaussian function to the asymmetric profiles of the tooth-saw and the gamma-type function. At longer sample length and similar degree of interdiffusion, the thermal conductivity is found to be lower in asymmetric profiles. Furthermore, it is found that with smooth concentration profiles where atomic diffusion at the interface takes place the thermal conductivity is higher compared to systems with atomically sharp concentration profiles.

  12. Towards Resonant-State THz Laser Based on Strained p-Ge and SiGe QW Structures

    Science.gov (United States)

    2006-07-01

    achieve intra-center population inversion for deep acceptors, such as copper, in p-Ge. 10. The technique, which allows us to solve Schroedinger ...strained Ge. 2. By using the developed method of solving Schroedinger equation with Luttinger Hamiltonian for complex valence band structure and the

  13. Effect of GeO2 deposition temperature in atomic layer deposition on electrical properties of Ge gate stack

    Science.gov (United States)

    Kanematsu, Masayuki; Shibayama, Shigehisa; Sakashita, Mitsuo; Takeuchi, Wakana; Nakatsuka, Osamu; Zaima, Shigeaki

    2016-08-01

    We investigated the effect of GeO2 deposition temperature (T depo) on electronic properties of Al/Al2O3/GeO2/Ge MOS capacitors. Capacitance-voltage characteristics show frequency dispersions under depletion and strong inversion conditions, which can be attributed from the interface states at the atomic layer deposition (ALD)-GeO2/Ge interface and from the defect states in the quasi-neutral region in the Ge substrate, respectively. We found that the interface state density (D it) shows similar values and energy distributions as T depo decreases to 200 from 300 °C, while a higher D it is observed at a T depo of 150 °C. Also, from the temperature dependence of conductance, the frequency dispersion under the strong inversion condition can be related to the minority carrier diffusion to the quasi-neutral region of the Ge substrate. The frequency dependence of conductance reveals that the undesirable increment of the bulk defect density can be suppressed by decreasing T depo. In this study, the bulk defect density in a MOS capacitor prepared at a T depo of 200 °C decreases one tenth compared with that at a T depo of 300 °C. The ALD of GeO2 at a low temperature of around 200 °C is effective for both obtaining a low D it and preventing the undesirable introduction of bulk defect density.

  14. TEM studies of Ge nanocrystal formation in PECVD grown SiO2:Ge/SiO2 multilayers

    Science.gov (United States)

    Agan, S.; Dana, A.; Aydinli, A.

    2006-06-01

    We investigate the effect of annealing on the Ge nanocrystal formation in multilayered germanosilicate-oxide films grown on Si substrates by plasma enhanced chemical vapour deposition (PECVD). The multilayered samples were annealed at temperatures ranging from 750 to 900 °C for 5 min under nitrogen atmosphere. The onset of formation of Ge nanocrystals, at 750 °C, can be observed via high resolution TEM micrographs. The diameters of Ge nanocrystals were observed to be between 5 and 14 nm. As the annealing temperature is raised to 850 °C, a second layer of Ge nanocrystals forms next to the original precipitation band, positioning itself closer to the substrate SiO2 interface. High resolution cross section TEM images, electron diffraction and electron energy-loss spectroscopy as well as energy-dispersive x-ray analysis (EDAX) data all indicate that Ge nanocrystals are present in each layer.

  15. Segregation of Sb in Ge epitaxial layers and its usage for the selective doping of Ge-based structures

    Energy Technology Data Exchange (ETDEWEB)

    Antonov, A. V.; Drozdov, M. N.; Novikov, A. V., E-mail: anov@ipmras.ru; Yurasov, D. V. [Institute for Physics of Microstructures of the Russian Academy of Sciences (Russian Federation)

    2015-11-15

    The segregation of Sb in Ge epitaxial layers grown by the method of molecular beam epitaxy on Ge (001) substrates is investigated. For a growth temperature range of 180–325°C, the temperature dependence is determined for the segregation ratio of Sb in Ge, which shows a sharp increase (by more than three orders of magnitude) with increasing temperature. The strong dependence of the segregation properties of Sb on the growth temperature makes it possible to adapt a method based on the controlled use of segregation developed previously for the doping of Si structures for the selective doping of Ge structures with a donor impurity. Using this method selectively doped Ge:Sb structures, in which the bulk impurity concentration varies by an order of magnitude at distances of 3–5 nm, are obtained.

  16. Unexpected Ge-Ge Contacts in the Two-Dimensional Ge4 Se3 Te Phase and Analysis of Their Chemical Cause with the Density of Energy (DOE) Function.

    Science.gov (United States)

    Küpers, Michael; Konze, Philipp M; Maintz, Stefan; Steinberg, Simon; Mio, Antonio M; Cojocaru-Mirédin, Oana; Zhu, Min; Müller, Merlin; Luysberg, Martina; Mayer, Joachim; Wuttig, Matthias; Dronskowski, Richard

    2017-08-14

    A hexagonal phase in the ternary Ge-Se-Te system with an approximate composition of GeSe0.75 Te0.25 has been known since the 1960s but its structure has remained unknown. We have succeeded in growing single crystals by chemical transport as a prerequisite to solve and refine the Ge4 Se3 Te structure. It consists of layers that are held together by van der Waals type weak chalcogenide-chalcogenide interactions but also display unexpected Ge-Ge contacts, as confirmed by electron microscopy analysis. The nature of the electronic structure of Ge4 Se3 Te was characterized by chemical bonding analysis, in particular by the newly introduced density of energy (DOE) function. The Ge-Ge bonding interactions serve to hold electrons that would otherwise go into antibonding Ge-Te contacts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Ion beam synthesis of SiGe alloy layers

    Energy Technology Data Exchange (ETDEWEB)

    Im, Seongil [Univ. of California, Berkeley, CA (United States)

    1994-05-01

    Procedures required for minimizing structural defects generated during ion beam synthesis of SiGe alloy layers were studied. Synthesis of 200 mm SiGe alloy layers by implantation of 120-keV Ge ions into <100> oriented Si wafers yielded various Ge peak concentrations after the following doses, 2 x 1016cm-2, 3 x 1016cm-2 (mid), and 5 x 1016cm-2 (high). Following implantation, solid phase epitaxial (SPE) annealing in ambient N2 at 800C for 1 hr. resulted in only slight redistribution of the Ge. Two kinds of extended defects were observed in alloy layers over 3 x l016cm-2cm dose at room temperature (RT): end-of-range (EOR) dislocation loops and strain-induced stacking faults. Density of EOR dislocation loops was much lower in alloys produced by 77K implantation than by RT implantation. Decreasing the dose to obtain 5 at% peak Ge concentration prevents strain relaxation, while those SPE layers with more than 7 at% Ge peak show high densities of misfit- induced stacking faults. Sequential implantation of C following high dose Ge implantation (12 at% Ge peak concentration in layer) brought about a remarkable decrease in density of misfit-induced stacking faults. For peak implanted C > 0.55 at%, stacking fault generation in the epitaxial layer was suppressed, owing to strain compensation by C atoms in the SiGe lattice. A SiGe alloy layer with 0.9 at% C peak concentration under a 12 at% Ge peak exhibited the best microstructure. Results indicate that optimum Ge/C ratio for strain compensation is between 11 and 22. The interface between amorphous and regrown phases (a/c interface) had a dramatic morphology change during its migration to the surface. Initial <100> planar interface decomposes into a <111> faceted interface, changing the growth kinetics; this is associated with strain relaxation by stacking fault formation on (111) planes in the a/c interface.

  18. The Effects of Annealing Temperatures on Composition and Strain in SixGe1−x Obtained by Melting Growth of Electrodeposited Ge on Si (100

    Directory of Open Access Journals (Sweden)

    Mastura Shafinaz Zainal Abidin

    2014-02-01

    Full Text Available The effects of annealing temperatures on composition and strain in SixGe1−x, obtained by rapid melting growth of electrodeposited Ge on Si (100 substrate were investigated. Here, a rapid melting process was performed at temperatures of 1000, 1050 and 1100 °C for 1 s. All annealed samples show single crystalline structure in (100 orientation. A significant appearance of Si-Ge vibration mode peak at ~400 cm−1 confirms the existence of Si-Ge intermixing due to out-diffusion of Si into Ge region. On a rapid melting process, Ge melts and reaches the thermal equilibrium in short time. Si at Ge/Si interface begins to dissolve once in contact with the molten Ge to produce Si-Ge intermixing. The Si fraction in Si-Ge intermixing was calculated by taking into account the intensity ratio of Ge-Ge and Si-Ge vibration mode peaks and was found to increase with the annealing temperatures. It is found that the strain turns from tensile to compressive as the annealing temperature increases. The Si fraction dependent thermal expansion coefficient of SixGe1−x is a possible cause to generate such strain behavior. The understanding of compositional and strain characteristics is important in Ge/Si heterostructure as these properties seem to give significant effects in device performance.

  19. Electrical characterization of SiGeSn grown on Ge substrate using ultra high vacuum chemical vapor deposition

    Science.gov (United States)

    Ahoujja, Mo; Kang, S.; Hamilton, M.; Yeo, Y. K.; Kouvetakis, J.; Menendez, J.

    2012-02-01

    There has been recently considerable interest in growing SiyGe1-x-ySnx alloys for the fabrication of photonic devices that could be integrated with Si technologies. We report temperature dependent Hall (TDH) measurements of the hole concentration and mobility from high quality p-type doped Si0.08Ge0.90Sn0.02 layers grown on p-type doped Ge substrates using ultra high vacuum chemical vapor deposition. The TDH measurements show the hole sheet density remains constant at low temperatures before slightly decreasing and dipping at ˜ 125 K. It then exponentially increases with temperature due to the activation of shallow acceptors. At temperatures above ˜ 450 K, the hole sheet density increases sharply indicating the onset of intrinsic conduction in the SiGeSn and/or Ge layers. To extract the electrical properties of the SiGeSn layer alone, a parametric fit using a multi layer conducting model is applied to the measured hole concentration and mobility data. The analysis yields boron and gallium doping concentrations of 3x10^17 cm-3 and 1x10^18 cm-3 with activation energies of 10 meV and 11 meV for the SiGeSn layer and Ge substrate, respectively. Furthermore, a temperature independent hole sheet concentration of ˜5x10^15 cm-2 with a mobility of ˜250 cm^2/Vs, which is believed to be due to an interfacial layer between the SiGeSn layer and the Ge substrate, is also determined.

  20. Monolithically Integrated Ge-on-Si Active Photonics

    Directory of Open Access Journals (Sweden)

    Jifeng Liu

    2014-07-01

    Full Text Available Monolithically integrated, active photonic devices on Si are key components in Si-based large-scale electronic-photonic integration for future generations of high-performance, low-power computation and communication systems. Ge has become an interesting candidate for active photonic devices in Si photonics due to its pseudo-direct gap behavior and compatibility with Si complementary metal oxide semiconductor (CMOS processing. In this paper, we present a review of the recent progress in Ge-on-Si active photonics materials and devices for photon detection, modulation, and generation. We first discuss the band engineering of Ge using tensile strain, n-type doping, Sn alloying, and separate confinement of Γ vs. L electrons in quantum well (QW structures to transform the material towards a direct band gap semiconductor for enhancing optoelectronic properties. We then give a brief overview of epitaxial Ge-on-Si materials growth, followed by a summary of recent investigations towards low-temperature, direct growth of high crystallinity Ge and GeSn alloys on dielectric layers for 3D photonic integration. Finally, we review the most recent studies on waveguide-integrated Ge-on-Si photodetectors (PDs, electroabsorption modulators (EAMs, and laser diodes (LDs, and suggest possible future research directions for large-scale monolithic electronic-photonic integrated circuits on a Si platform.

  1. Quantum Dot TiO2-Ge Solar Cells

    Science.gov (United States)

    Church, Carena; Muthuswamy, Elayaraja; Kauzlarich, Susan; Carter, Sue

    2014-03-01

    Colloidal germanium (Ge) quantum dots (CQDs) are attractive solar materials due to their low toxicity compared to Pb- or Cd- based nanocrystals (NC), low cost, and optimal, tunable bandgap for both increased IR response and potential power conversion efficiency (η) boosts from Multiple Exciton Generation (MEG). We report on the successful fabrication and characterization of spun-cast donor/acceptor type TiO2-Ge CQD solar cells utilizing Ge colloidal quantum dots (CQD) synthesized via a facile microwave method as the active layer. We find that our Ge QD size performance-related trends are similar to other QD systems studied. Additionally, our best heterojunction devices achieved short circuit currents (JSC) of 450 μA and open circuit voltages (VOC) of 0.335 V, resulting in η = 0.022 %. While this represents significant increases over previous Ge CQD PV (85 % over hybrid Ge-P3HT PV, 350 % over Ge NC PV), our photocurrents are still much lower than other NC systems. Analysis of intensity-dependent J-V characteristics reveal that our currents are limited by a space-charge region that forms leading to unbalanced charge extraction. We conclude by discussing a variety of film treatments and device structures we have tested to increase JSC.

  2. Photoluminescence of phosphorus atomic layer doped Ge grown on Si

    Science.gov (United States)

    Yamamoto, Yuji; Nien, Li-Wei; Capellini, Giovanni; Virgilio, Michele; Costina, Ioan; Schubert, Markus Andreas; Seifert, Winfried; Srinivasan, Ashwyn; Loo, Roger; Scappucci, Giordano; Sabbagh, Diego; Hesse, Anne; Murota, Junichi; Schroeder, Thomas; Tillack, Bernd

    2017-10-01

    Improvement of the photoluminescence (PL) of Phosphorus (P) doped Ge by P atomic layer doping (ALD) is investigated. Fifty P delta layers of 8 × 1013 cm‑2 separated by 4 nm Ge spacer are selectively deposited at 300 °C on a 700 nm thick P-doped Ge buffer layer of 1.4 × 1019 cm‑3 on SiO2 structured Si (100) substrate. A high P concentration region of 1.6 × 1020 cm‑3 with abrupt P delta profiles is formed by the P-ALD process. Compared to the P-doped Ge buffer layer, a reduced PL intensity is observed, which might be caused by a higher density of point defects in the P delta doped Ge layer. The peak position is shifted by ∼0.1 eV towards lower energy, indicating an increased active carrier concentration in the P-delta doped Ge layer. By introducing annealing at 400 °C to 500 °C after each Ge spacer deposition, P desorption and diffusion is observed resulting in relatively uniform P profiles of ∼2 × 1019 cm‑3. Increased PL intensity and red shift of the PL peak are observed due to improved crystallinity and higher active P concentration.

  3. B electrical activation in crystalline and preamorphized Ge

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, E. [MATIS CNR-INFM and Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 64, 95123 Catania (Italy); Impellizzeri, G. [MATIS CNR-INFM and Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 64, 95123 Catania (Italy)], E-mail: giuliana.impellizzeri@ct.infn.it; Mirabella, S.; Piro, A.M.; Irrera, A.; Grimaldi, M.G. [MATIS CNR-INFM and Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 64, 95123 Catania (Italy)

    2008-12-05

    In this work we compare the B electrical activity in crystalline (c-Ge) and preamorphized Ge (PAI-Ge), in order to elucidate the activation mechanisms involved in the two cases and evidence the possible advantages of an approach over to the other. With this aim, we independently measured the hole fluence and the sheet resistance, thus extracting the carrier mobility, as a function of the implanted B fluence. In particular, we evidenced that it is possible to reproduce the metastability of the PAI process implanting B in c-Ge at very high fluences. However, by properly choosing the implantation conditions in c-Ge, in such a way to disable dynamic annealing during implantation, the activation of B can be raised up to the level attainable in PAI-Ge also for lower B fluences. Finally, the thermal evolution of the formed junction was tested, evidencing a high stability under annealing up to 550 deg. C in both c- and PAI-Ge.

  4. GeNF - Experimental report 2007

    Energy Technology Data Exchange (ETDEWEB)

    Pranzas, P.K.; Schreyer, A.; Willumeit, R. (eds.) [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung

    2008-11-05

    At the Geesthacht Neutron Facility GeNF about 203 experiments were performed in 2007 by GKSS and by or for external users, partners or contractors. In most cases the measurements were performed and analysed in cooperation by the guests and by the GKSS staff or by the permanent external user group staff. The activities, which are based on a proposal procedure and on the in house R and D program, are reported in 70 contributions in the present annual experimental report for the year 2007. The contributions may contain one or also several combined experiments. During 2007 the GKSS research reactor FRG-1 achieved an operation time of 204 days at the full 5 MW reactor power providing a neutron flux of ca. 1.4 x 10{sup 14} thermal neutrons/cm{sup 2}s. In May/June 2007 the FRG-1 was upgraded with a new cold neutron source yielding a flux increase at the five instruments using cold neutrons of up to 40 %. The focus of the in house R and D work at GeNF instruments in 2007 was the characterisation of nano-structures in engineering materials, the analysis of stresses and textures in welds and technical structures at SANS-2, DCD, ARES-2 and TEX-2, the structural investigation of hydrogen containing substances such as polymers, colloids and biological macromolecules at SANS-1 as well as the characterisation of magnetic thin films at NeRo, PNR, POLDI and ROeDI. The modern experiment control hardware and software based on LabView was continuously improved on all instruments. In the appendices I and II the experimental reports of the GKSS outstation at the FRM II are attached as well as of the GKSS outstation at DESY. At the neutron reflectometer REFSANS at FRM II measurements are possible using a broad range of the scattering vector with reflectivities up to 10{sup -7}. Three reports show the activities of GKSS in the field of texture measurement at the instrument STRESS-SPEC. The instrument HARWI II at DESY is accepted very well by the community and is overbooked in all fields

  5. GeNF - Experimental report 2008

    Energy Technology Data Exchange (ETDEWEB)

    Pranzas, Philipp Klaus; Mueller, Martin; Willumeit, Regine; Schreyer, Andreas (eds.) [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung

    2009-12-11

    At the Geesthacht Neutron Facility GeNF about 182 experiments were performed in 2008 by GKSS and by or for external users, partners or contractors. In most cases the measurements were performed and analysed in cooperation by the guests, by GKSS staff or by the permanent external user group staff. The activities, which are based on a proposal procedure and on the in house R and D program, are reported in 76 contributions in the present annual experimental report for the year 2008. The contributions may contain several combined experiments. During 2008 the GKSS research reactor FRG-1 achieved an operation time of 175 days at the full 5 MW reactor power providing a neutron flux of ca. 1.4.10{sup 14} thermal neutrons/cm{sup 2} s. The focus of the in house R and D work at GeNF instruments in 2008 was the characterisation of nanostructures in engineering materials, the analysis of stresses and textures in welds and technical structures at SANS-2, DCD, ARES-2 and TEX-2, the structural investigation of hydrogen containing substances such as polymers, colloids and biological macromolecules at SANS-1 as well as the characterisation of magnetic thin films at NeRo, PNR, POLDI and ROeDI. The modern experiment control hardware (e.g. sample environments, like magnets, cryostats or furnaces) and software based on LabView was continuously improved on all instruments. In the appendices I and II the experimental reports of the GKSS outstation at the FRM II are attached as well as of the GKSS outstation at DESY. The massive activity at the FRM II outstation is documented by the increasing number of REFSANS reports, accumulated to nine. Three reports show the activities of GKSS in the field of texture measurement at the instrument STRESS-SPEC. The instrument HARWI II at the synchrotron storage ring DORIS III at DESY is accepted very well by the community and is heavily overbooked in all fields (tomography, diffraction, etc.). After an 8-month shutdown period for an upgrade in the frame

  6. Interpreting 750 GeV diphoton excess in plain NMSSM

    Directory of Open Access Journals (Sweden)

    Marcin Badziak

    2016-09-01

    Full Text Available NMSSM has enough ingredients to explain the diphoton excess at 750 GeV: singlet-like (pseudo scalar (a s and higgsinos as heavy vector-like fermions. We consider the production of the 750 GeV singlet-like pseudo scalar a from a decay of the doublet-like pseudo scalar A, and the subsequent decay of a into two photons via higgsino loop. We demonstrate that this cascade decay of the NMSSM Higgs bosons can explain the diphoton excess at 750 GeV.

  7. Interpreting 750 GeV diphoton excess in plain NMSSM

    Science.gov (United States)

    Badziak, Marcin; Olechowski, Marek; Pokorski, Stefan; Sakurai, Kazuki

    2016-09-01

    NMSSM has enough ingredients to explain the diphoton excess at 750 GeV: singlet-like (pseudo) scalar (a) s and higgsinos as heavy vector-like fermions. We consider the production of the 750 GeV singlet-like pseudo scalar a from a decay of the doublet-like pseudo scalar A, and the subsequent decay of a into two photons via higgsino loop. We demonstrate that this cascade decay of the NMSSM Higgs bosons can explain the diphoton excess at 750 GeV.

  8. Spin-polarized photoemission from SiGe heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, A.; Bottegoni, F.; Isella, G.; Cecchi, S.; Chrastina, D.; Finazzi, M.; Ciccacci, F. [LNESS-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2013-12-04

    We apply the principles of Optical Orientation to measure by Mott polarimetry the spin polarization of electrons photoemitted from different group-IV heterostructures. The maximum measured spin polarization, obtained from a Ge/Si{sub 0.31}Ge{sub 0.69} strained film, undoubtedly exceeds the maximum value of 50% attainable in bulk structures. The explanation we give for this result lies in the enhanced band orbital mixing between light hole and split-off valence bands as a consequence of the compressive strain experienced by the thin Ge layer.

  9. The Majorana Ge-76 Double-Beta Decay Project

    CERN Document Server

    Aalseth, C E; Barabash, A S; Bowyer, T W; Brodzinski, R L; Brudanin, V B; Collar, J I; Doe, P J; Egorov, S; Elliott, S R; Farach, H A; Gaitskell, R J; Jordan, D; Kochetov, O I; Konovalov, S V; Kouzes, R T; Miley, H S; Pitts, W K; Reeves, J H; Robertson, R G H; Sandukovsky, V G; Smith, E; Stekhanov, V; Thompson, R C; Tornow, W; Umatov, V I; Warner, R A; Webb, J; Wilkerson, J F; Young, A

    2002-01-01

    The Majorana Experiment is a next-generation Ge-76 double-beta decay search. It will employ 500 kg of Ge, isotopically enriched to 86% in Ge-76, in the form of 200 detectors in a close-packed array for high granularity. Each crystal will be electronically segmented, with each region fitted with pulse-shape analysis electronics. A half-life sensitivity is predicted of 4.2e27 y or < 0.02-0.07 eV, depending on the nuclear matrix elements used to interpret the data.

  10. A New 76Ge Double Beta Decay Experiment at LNGS

    OpenAIRE

    Abt, I.; Altmann, M; Bakalyarov, A.; Barabanov, I.; Bauer, C; Bellotti, E.(Dipartimento di Fisica, Università Milano Bicocca, Milan, Italy); Belyaev, S. T.(National Research Centre “Kurchatov Institute”, Moscow, Russia); Bezrukov, L.(Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia); Brudanin, V.; Buettner, C.; Bolotsky, V. P.; Caldwell, A.; Cattadori, C.; Clement, H.; di Vacri, A.

    2004-01-01

    This Letter of Intent has been submitted to the Scientific Committee of the INFN Laboratori Nazionali del Gran Sasso (LNGS) in March 2004. It describes a novel facility at the LNGS to study the double beta decay of 76Ge using an (optionally active) cryogenic fluid shield. The setup will allow to scrutinize with high significance on a short time scale the current evidence for neutrinoless double beta decay of 76Ge using the existing 76Ge diodes from the previous Heidelberg-Moscow and IGEX expe...

  11. GeSn/Si Avalanche Photodetectors on Si substrates

    Science.gov (United States)

    2016-09-16

    Photodetectors on Si substrates Report Title In this project, firstly, the material growth of GeSn by chemical vapor deposition (CVD) system has been...between GeSn and other market dominating IR detectors in short-IR wavelength (First time reported the D* of a GeSn detector in the world). The D* of...Standard Form 298 (Rev 8/98) Prescribed by ANSI Std. Z39.18 Final Report W911NF-13-1-0196 64461-EL-DRP.43 479-575-7265 a. REPORT 14. ABSTRACT 16

  12. Improvement on Frequency Performance of SOI SiGe HBT

    Institute of Scientific and Technical Information of China (English)

    DAI Guang-hao; WANG Sheng-rong; LI Wen-jie

    2006-01-01

    Based on the advantages of SOI technology,the frequency performance of SiGe HBT with SOI structure has been simulated. Compared with bulk SiGe HBT,the results show that the buried oxide layer(BOX) can reduce collector-base capacitance CCB with the maximum value 89.3%,substrate-base capacitance CSB with 94.6%,and the maximum oscillation frequency is improved by 2.7. The SOI structure improves the frequency performance of SiGe HBT,which is adaptable to high-speed and high power applications.

  13. Gadolinium scandium germanide, Gd2Sc3Ge4

    Directory of Open Access Journals (Sweden)

    Sumohan Misra

    2009-04-01

    Full Text Available Gd2Sc3Ge4 adopts the orthorhombic Pu5Rh4-type structure. The crystal structure contains six sites in the asymmetric unit: two sites are statistically occupied by rare-earth atoms with Gd:Sc ratios of 0.967 (4:0.033 (4 and 0.031 (3:0.969 (3, one site (.m. symmetry is occupied by Sc atoms, and three distinct sites (two of which with .m. symmetry are occupied by Ge atoms. The rare-earth atoms form two-dimensional slabs with Ge atoms occupying the trigonal-prismatic voids.

  14. Structural evolution of Ge-rich Si{sub 1−x}Ge{sub x} films deposited by jet-ICPCVD

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu; Yang, Meng; Wang, Gang [Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Wei, Xiaoxu; Wang, Junzhuan; Li, Yun; Zheng, Youdou; Shi, Yi, E-mail: yshi@nju.edu.cn [Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Collaborative Innovation Center of Advanced Micro-structures, Nanjing University, Nanjing 210093 (China); Zou, Zewen [College of Physics and Electronics Information, Anhui Normal University, Wuhu 241000 (China)

    2015-11-15

    Amorphous Ge-rich Si{sub 1−x}Ge{sub x} films with local Ge-clustering were deposited by dual-source jet-type inductively coupled plasma chemical-vapor deposition (jet-ICPCVD). The structural evolution of the deposited films annealed at various temperatures (Ta) is investigated. Experimental results indicate that the crystallization occurs to form Ge and Si clusters as Ta = 500 °C. With raising Ta up to 900 °C, Ge clusters percolate together and Si diffuses and redistributes to form a Ge/SiGe core/shell structure, and some Ge atoms partially diffuse to the surface as a result of segregation. The present work will be helpful in understanding the structural evolution process of a hybrid SiGe films and beneficial for further optimizing the microstructure and properties.

  15. Optical absorption in highly strained Ge/SiGe quantum wells: The role of Γ→ Δ scattering

    Science.gov (United States)

    Lever, L.; Ikonić, Z.; Valavanis, A.; Kelsall, R. W.; Myronov, M.; Leadley, D. R.; Hu, Y.; Owens, N.; Gardes, F. Y.; Reed, G. T.

    2012-12-01

    We report the observation of the quantum-confined Stark effect in Ge/SiGe multiple quantum well heterostructures grown on Si0.22Ge0.78 virtual substrates. The large compressive strain in the Ge quantum well layers caused by the lattice mismatch with the virtual substrate results in a blue shift of the direct absorption edge, as well as a reduction in the Γ-valley scattering lifetime because of strain-induced splittings of the conduction band valleys. We investigate theoretically the Γ-valley carrier lifetimes by evaluating the Γ →L and Γ →Δ scattering rates in strained Ge/SiGe semiconductor heterostructures. These scattering rates are used to determine the lifetime broadening of excitonic peaks and the indirect absorption in simulated absorption spectra, which are compared with measured absorption spectra for quantum well structures with systematically varied dimensions. We find that Γ →Δ scattering is significant in compressively strained Ge quantum wells and that the Γ-valley electron lifetime is less than 50 fs in the highly strained structures reported here, where Γ →Δ scattering accounted for approximately half of the total scattering rate.

  16. Lowering the effective work function via oxygen vacancy formation on the GeO2/Ge interface

    Science.gov (United States)

    Lee, Tae In; Seo, Yujin; Moon, Jungmin; Ahn, Hyun Jun; Yu, Hyun-Young; Hwang, Wan Sik; Cho, Byung Jin

    2017-04-01

    The use of a GeO2 interfacial layer (IL) between a high-k dielectric and a Ge substrate helps to reduce the interface state density in Ge MOS devices. We report that the presence of the GeO2 IL changes the effective work function (eWF) of the gate stack when annealed after high-k dielectric deposition. The eWF is reduced from 4.31 eV to 3.98 eV for TaN and from 5.00 eV to 4.44 eV for Ni. Consequently, the threshold voltage (Vth) decreases from 0.69 V to 0.21 V for Ni after post deposition annealing. Our investigation confirms that the generation of oxygen vacancies in the GeO2 IL near the Ge substrate is the main cause of the eWF modulation. In addition, the reliability of the GeO2 IL is investigated via the conductance method and a constant-current stress test.

  17. Band alignments at strained Ge1‑x Sn x /relaxed Ge1‑y Sn y heterointerfaces

    Science.gov (United States)

    Lan, H.-S.; Liu, C. W.

    2017-04-01

    Type-I, type-II, reverse type-I, and reverse type-II band alignments are found theoretically in strained Ge1‑x Sn x (0  ⩽  x  ⩽  0.3) grown on relaxed Ge1‑y Sn y substrates (0  ⩽  y  ⩽  0.3) using the model-solid theory. The prerequisite bandgaps, and energy difference between the top valence band edge and the average valence band position of GeSn are obtained by the nonlocal empirical pseudopotential method. For the indirect-gap (L valleys) Ge1‑x Sn x on relaxed Ge1‑y Sn y , the band alignments are type-I and reverse type-I under biaxial compressive strain (x  >  y) and biaxial tensile strain (x  <  y), respectively. For the direct-gap (Γ valley) Ge1‑x Sn x on relaxed Ge1‑y Sn y , the biaxial compressive strain yields type-I and type-II alignment, while the biaxial tensile strain yields reverse type-I and reverse type-II alignments.

  18. Reduction of threading dislocation density in Ge/Si using a heavily As-doped Ge seed layer

    Directory of Open Access Journals (Sweden)

    Kwang Hong Lee

    2016-02-01

    Full Text Available High quality germanium (Ge epitaxial film is grown directly on silicon (001 substrate with 6° off-cut using a heavily arsenic (As doped Ge seed layer. The growth steps consists of (i growth of a heavily As-doped Ge seed layer at low temperature (LT, at 400 °C, (ii Ge growth with As gradually reduced to zero at high temperature (HT, at 650 °C, (iii pure Ge growth at HT. This is followed by thermal cyclic annealing in hydrogen at temperature ranging from 600 to 850 °C. Analytical characterization have shown that the Ge epitaxial film with a thickness of ∼1.5 µm experiences thermally induced tensile strain of 0.20% with a treading dislocation density (TDD of mid 106/cm2 which is one order of magnitude lower than the control group without As doping and surface roughness of 0.37 nm. The reduction in TDD is due to the enhancement in velocity of dislocations in an As-doped Ge film.

  19. Luminescence of one dimensional ZnO, GeO{sub 2}–Zn{sub 2}GeO{sub 4} nanostructure through thermal evaporation of Zn and Ge powder mixture

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Vuong-Hung, E-mail: vuong.phamhung@hust.edu.vn; Kien, Vu Trung; Tam, Phuong Dinh; Huy, Pham Thanh

    2016-07-15

    Graphical abstract: - Highlights: • ZnO and GeO{sub 2}–ZnGeO{sub 4} nanowires were fabricated by thermal evaporation of Zn and Ge powder mixture. • Morphology of specimens were observed to have a nanowire structure to rod-like morphology. • Strong NBE emission band with suppressed visible green emission band were observed on the dominant ZnO nanowires. • Strong emission of ∼530 nm were observed on the GeO{sub 2}–Zn{sub 2}GeO{sub 4} nanowires. - Abstract: This paper reports the first attempt for fabrication of thermal evaporated Zn–Ge powder mixture to achieve near-band-edge (NBE) emission of ZnO and visible emission of GeO{sub 2}–Zn{sub 2}GeO{sub 4} nanowires with controllable intensities. The nanowires were fabricated by thermal evaporation of Zn and Ge powder mixture, particularly, by using different Zn:Ge ratio, temperature and evaporated times. The morphology of nanowires was depended on the Zn and Ge ratio that was observed to have a nanowire structure to rod-like morphology. The thermal evaporation of Zn:Ge powder mixture resulted in formation of dominant ZnO or GeO{sub 2}–Zn{sub 2}GeO{sub 4} nanowires as a function of evaporated parameters. These results suggest that the application of thermal evaporation of Zn and Ge mixture for potential application in synthesis of ZnO or GeO{sub 2}–Zn{sub 2}GeO{sub 4} nanowires for optoelectronic field.

  20. Sn-based Ge/Ge0.975Sn0.025/Ge p-i-n photodetector operated with back-side illumination

    Science.gov (United States)

    Chang, C.; Li, H.; Huang, S. H.; Cheng, H. H.; Sun, G.; Soref, R. A.

    2016-04-01

    We report an investigation of a GeSn-based p-i-n photodetector grown on a Ge wafer that collects light signal from the back of the wafer. Temperature dependent absorption measurements performed over a wide temperature range (300 K down to 25 K) show that (a) absorption starts at the indirect bandgap of the active GeSn layer and continues up to the direct bandgap of the Ge wafer, and (b) the peak responsivity increases rapidly at first with decreasing temperature, then increases more slowly, followed by a decrease at the lower temperatures. The maximum responsivity happens at 125 K, which can easily be achieved with the use of liquid nitrogen. The temperature dependence of the photocurrent is analyzed by taking into consideration of the temperature dependence of the electron and hole mobility in the active layer, and the analysis result is in reasonable agreement with the data in the temperature regime where the rapid increase occurs. This investigation demonstrates the feasibility of a GeSn-based photodiode that can be operated with back-side illumination for applications in image sensing systems.

  1. The Ratio of Jet Cross Sections at s**(1/2)=630 GeV and 1800 GeV

    CERN Document Server

    Abbott, B; Abramov, V; Acharya, B S; Adams, D L; Adams, M; Alves, G A; Amos, N; Anderson, E W; Baarmand, M M; Babintsev, V V; Babukhadia, L R; Baden, A; Baldin, B Yu; Balm, P W; Banerjee, S; Bantly, J; Barberis, E; Baringer, P; Bartlett, J F; Bassler, U; Bean, A; Begel, M; Belyaev, A; Beri, S B; Bernardi, G; Bertram, I; Besson, A; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Bhattacharjee, M; Blazey, G C; Blessing, S; Böhnlein, A; Bozhko, N; Borcherding, F; Brandt, A; Breedon, R; Briskin, G M; Brock, R; Brooijmans, G; Bross, A; Buchholz, D; Bühler, M; Büscher, V; Burtovoi, V S; Butler, J M; Canelli, F; Carvalho, W S; Casey, D; Casilum, Z; Castilla-Valdez, H; Chakraborty, D; Chan, K M; Chekulaev, S V; Cho, D K; Choi, S; Chopra, S; Christenson, J H; Chung, M; Claes, D; Clark, A R; Cochran, J; Coney, L; Connolly, B; Cooper, W E; Coppage, D; Cummings, M A C; Cutts, D; Dahl, O I; Davis, G A; Davis, K; De, K; Del Signore, K; Demarteau, M; Demina, R; Demine, P; Denisov, D S; Denisov, S P; Desai, S V; Diehl, H T; Diesburg, M; DiLoreto, G; Doulas, S; Draper, P; Ducros, Y; Dudko, L V; Duensing, S; Dugad, S R; Dyshkant, A; Edmunds, D L; Ellison, J; Elvira, V D; Engelmann, R; Eno, S; Eppley, G; Ermolov, P; Eroshin, O V; Estrada, J K; Evans, H; Evdokimov, V N; Fahland, T; Fehér, S; Fein, D; Ferbel, T; Fisk, H E; Fisyak, Yu; Flattum, E M; Fleuret, F; Fortner, M R; Frame, K C; Fuess, S; Gallas, E J; Galjaev, A N; Gartung, P E; Gavrilov, V; Genik, R J; Genser, K; Gerber, C E; Gershtein, Yu; Gibbard, B; Gilmartin, R; Ginther, G; Gómez, B; Gómez, G; Goncharov, P I; González-Solis, J L; Gordon, H; Goss, L T; Gounder, K; Goussiou, A; Graf, N; Graham, G; Grannis, P D; Green, J A; Greenlee, H; Grinstein, S; Groer, L S; Grudberg, P M; Grünendahl, S; Sen-Gupta, A; Gurzhev, S N; Gutíerrez, G; Gutíerrez, P; Hadley, N J; Haggerty, H; Hagopian, S L; Hagopian, V; Hahn, K S; Hall, R E; Hanlet, P; Hansen, S; Hauptman, J M; Hays, C; Hebert, C; Hedin, D; Heinson, A P; Heintz, U; Heuring, T C; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoftun, J S; Hou, S; Huang, Y; Ito, A S; Jerger, S A; Jesik, R; Johns, K; Johnson, M; Jonckheere, A M; Jones, M; Jöstlein, H; Juste, A; Kahn, S; Kajfasz, E; Karmanov, D E; Karmgard, D J; Kehoe, R; Kim, S K; Klima, B; Klopfenstein, C; Knuteson, B; Ko, W; Kohli, J M; Kostritskii, A V; Kotcher, J; Kotwal, A V; Kozelov, A V; Kozlovskii, E A; Krane, J; Krishnaswamy, M R; Krzywdzinski, S; Kubantsev, M A; Kuleshov, S; Kulik, Y; Kunori, S; Kuznetsov, V E; Landsberg, G L; Leflat, A; Lehner, F; Li, J; Li, Q Z; Lima, J G R; Lincoln, D; Linn, S L; Linnemann, J T; Lipton, R; Lucotte, A; Lueking, L H; Lundstedt, C; Maciel, A K A; Madaras, R J; Manankov, V; Mao, H S; Marshall, T; Martin, M I; Martin, R D; Mauritz, K M; May, B; Mayorov, A A; McCarthy, R; McDonald, J; McMahon, T; Melanson, H L; Meng, X C; Merkin, M; Merritt, K W B; Miao, C; Miettinen, H; Mihalcea, D; Mincer, A; Mishra, C S; Mokhov, N V; Mondal, N K; Montgomery, H E; Moore, R W; Mostafa, M A; Da Motta, H; Nagy, E; Nang, F; Narain, M; Narasimham, V S; Neal, H A; Negret, J P; Negroni, S; Norman, D; Oesch, L H; Oguri, V; Olivier, B; Oshima, N; Padley, P; Pan, L J; Para, A; Parashar, N; Partridge, R; Parua, N; Paterno, M; Patwa, A; Pawlik, B; Perkins, J; Peters, M; Peters, O; Piegaia, R; Piekarz, H; Pope, B G; Popkov, E; Prosper, H B; Protopopescu, S D; Qian, J; Quintas, P Z; Raja, R; Rajagopalan, S; Ramberg, E; Rapidis, P A; Reay, N W; Reucroft, S; Rha, J; Rijssenbeek, M; Rockwell, T; Roco, M T; Rubinov, P M; Ruchti, R C; Rutherfoord, John P; Santoro, A F S; Sawyer, L; Schamberger, R D; Schellman, H; Schwartzman, A; Scully, J R; Sen, N; Shabalina, E; Shankar, H C; Shivpuri, R K; Shpakov, D; Shupe, M A; Sidwell, R A; Simák, V; Singh, H; Singh, J B; Sirotenko, V I; Slattery, P F; Smith, E; Smith, R P; Snihur, R; Snow, G A; Snow, J; Snyder, S; Solomon, J; Sorin, V; Sosebee, M; Sotnikova, N; Soustruznik, K; Souza, M; Stanton, N R; Steinbruck, G; Stephens, R W; Stevenson, M L; Stichelbaut, F; Stoker, D; Stolin, V; Stoyanova, D A; Strauss, M; Streets, K; Strovink, M; Stutte, L; Sznajder, A; Taylor, W; Tentindo-Repond, S; Thompson, J; Toback, D; Tripathi, S M; Trippe, T G; Turcot, A S; Tuts, P M; Van Gemmeren, P; Vaniev, V; Van Kooten, R; Varelas, N; Volkov, A A; Vorobev, A P; Wahl, H D; Wang, H; Wang, Z M; Warchol, J; Watts, G; Wayne, M; Weerts, H; White, A; White, J T; Whiteson, D; Wightman, J A; Wijngaarden, D A; Willis, S; Wimpenny, S J; Wirjawan, J V D; Womersley, J; Wood, D R; Yamada, R; Yamin, P; Yasuda, T; Yip, K; Youssef, S; Yu, J; Yu, Z; Zanabria, M E; Zheng, H; Zhou, Z; Zhu, Z H; Zielinski, M; Zieminska, D; Zieminski, A; Zutshi, V; Zverev, E G; Zylberstejn, A

    2001-01-01

    The DO Collaboration has measured the inclusive jet cross section in proton-antiproton collisions at s**2 = 630 GeV. The results for pseudorapidities -0.5 to 0.5 are combined with our previous results at s**2 = 1800 GeV to form a ratio of cross sections with smaller uncertainties than either individual measurement. Next-to-leading-order QCD predictions show excellent agreement with the measurement at 630 GeV; agreement is also satisfactory for the ratio. Specifically, despite a 10% to 15% difference in the absolute normalization, the dependence of the ratio on jet transverse momentum is very similar for data and theory.

  2. Temperature spectra of conductance of Ge/Si p-i-n structures with Ge quantum dots

    Science.gov (United States)

    Izhnin, Ihor I.; Fitsych, Olena I.; Pishchagin, Anton A.; Kokhanenko, Andrei P.; Voitsekhovskii, Alexander V.; Dzyadukh, Stanislav M.; Nikiforov, Alexander I.

    2017-02-01

    This work presents results of investigation of Ge/Si p-i-n structures with Ge quantum dots in the i-region by the method of admittance spectroscopy. The structures contain multiple layers with Ge quantum dots separated by thin 5 nm layers of Si in the intrinsic region. Two peaks are observed on the temperature dependences of conductance of the investigated heterostructures. It is revealed that the second peak is broadened and corresponds to a system of closely lying energy levels.

  3. Hard-photon emission from 150-GeV electrons incident on Si and Ge single crystals near axial directions

    Energy Technology Data Exchange (ETDEWEB)

    Medenwaldt, R.; Moller, S.P.; Sorensen, A.H.; Tang-Petersen, S.; Uggerhoj, E. (Institute of Physics, University of Aarhus, DK-8000 Aarhus C, Denmark (DK)); Elsener, K. (European Organization for Nuclear Research (CERN), CH-1211 Geneva 23, Switzerland (CH)); Hage-Ali, M.; Siffert, P.; Stoquert, J. (Centre de Recherches Nucleaires, F-67037 Strasbourg CEDEX, France (FR)); Maier, K. (The Max-Planck Institut fuer Metallforschung, D-7000 Stuttgart 80, Federal Republic of Germany (DE))

    1989-12-25

    The emission of high-energy photons from 150-GeV electrons traversing single crystals near axial directions is studied experimentally for Ge and, for the first time, also for Si. Enhancements relative to random up to 2 orders of magnitude are observed. For incident angles much less than the critical channeling angle {psi}{sub 1} a pronounced peak appears in the photon spectra near {similar to}85% of the electron energy for both the Si and the Ge crystals. The peak disappears for incident angles larger than {similar to}0.3{psi}{sub 1}. The experimental findings are compared to theoretical results.

  4. Ge-Photodetectors for Si-Based Optoelectronic Integration

    Directory of Open Access Journals (Sweden)

    Sungjoo Lee

    2011-01-01

    Full Text Available High speed photodetectors are a key building block, which allow a large wavelength range of detection from 850 nm to telecommunication standards at optical fiber band passes of 1.3–1.55 µm. Such devices are key components in several applications such as local area networks, board to board, chip to chip and intrachip interconnects. Recent technological achievements in growth of high quality SiGe/Ge films on Si wafers have opened up the possibility of low cost Ge-based photodetectors for near infrared communication bands and high resolution spectral imaging with high quantum efficiencies. In this review article, the recent progress in the development and integration of Ge-photodetectors on Si-based photonics will be comprehensively reviewed, along with remaining technological issues to be overcome and future research trends.

  5. Nanoscale elemental quantification in heterostructured SiGe nanowires.

    Science.gov (United States)

    Hourani, W; Periwal, P; Bassani, F; Baron, T; Patriarche, G; Martinez, E

    2015-05-14

    The nanoscale chemical characterization of axial heterostructured Si1-xGex nanowires (NWs) has been performed using scanning Auger microscopy (SAM) through local spectroscopy, line-scan and depth profile measurements. Local Auger profiles are realized with sufficient lateral resolution to resolve individual nanowires. Axial and radial composition heterogeneities are highlighted. Our results confirm the phenomenon of Ge radial growth forming a Ge shell around the nanowire. Moreover, quantification is performed after verifying the absence of preferential sputtering of Si or Ge on a bulk SiGe sample. Hence, reliable results are obtained for heterostructured NW diameters higher than 100 nm. However, for smaller sizes, we have noticed that the sensitivity factors evaluated from bulk samples cannot be used because of edge effects occurring for highly topographical features and a modified contribution of backscattered electrons.

  6. High Temperature Stable Nanocrystalline SiGe Thermoelectric Material

    Science.gov (United States)

    Yang, Sherwin (Inventor); Matejczyk, Daniel Edward (Inventor); Determan, William (Inventor)

    2013-01-01

    A method of forming a nanocomposite thermoelectric material having microstructural stability at temperatures greater than 1000 C. The method includes creating nanocrystalline powder by cryomilling. The method is particularly useful in forming SiGe alloy powder.

  7. THE EFFECT OF Ge-132 ON ULTRASTRUCTURE OF CULTURED MELANOCYTES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective To elucidate the effect of Ge-132 on the growth of melanocytes. Mothods Melanocyes from epidermis were cultured and purified ;the second generation of the cell was used for study ;the cells were divided into two groups randomly,to group A, Ge-132 was added to the media at 0.04mg/L ;to group B ,common culturing method was used without Ge-132. After 5d, the cells were seperated by digestion for study by transmission electronic micro- scope. Results Compared to group B, the vacuioes of the cells were increased,mitochondria distended, endoplasmic reticulum dilated and the number of melanosome declined in the group A. Conclusion Ge-132 can inhibit the melanocyte's growth at a certain concentration and might be used for treating pigmented diseases.

  8. Si-Ge-metal ternary phase diagram calculations

    Science.gov (United States)

    Fleurial, J. P.; Borshchevsky, A.

    1990-01-01

    Solution crystal growth and doping conditions of Si-Ge alloys used for high-temperature thermoelectric generation are determined here. Liquid-phase epitaxy (LPE) has been successfully employed recently to obtain single-crystalline homogeneous layers of Si-Ge solid solutions from a liquid metal solvent. Knowledge of Si-Ge-metallic solvent ternary phase diagrams is essential for further single-crystal growth development. Consequently, a thermodynamic equilibrium model was used to calculate the phase diagrams of the Si-Ge-M systems, including solid solubilities, where M is Al, Ga, In, Sn, Pb, Sb, or Bi. Good agreement between calculated liquidus and solidus data and experimental DTA and microprobe results was obtained. The results are used to compare the suitability of the different systems for crystal growth (by LPE-type process).

  9. DESIGN AND FABRICATION OF Si/SiGe PMOSFETs

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on theoretical analysis and computer-aided simulation, optimized design prin-ciples for Si/SiGe PMOSFET are given in this paper, which include choice of gate materials, determination of germanium percentage and profile in SiGe channel, optimization of thickness of dioxide and silicon cap layer, and adjustment of threshold voltage.In the light of these principles, a SiGe PMOSFET is designed and fabricated successfully.Measurement indicates that the SiGe PMOSFET's(L=2μ同洒45 mS/mm(300K) and 92 mS/mm(77K) ,while that is 33mS/mm (300K) and 39mS/mm (77K) in Si PMOSFET with the same structure.

  10. DESIGN AND FABRICATION OF Si/SiGe PMOSFETs

    Institute of Scientific and Technical Information of China (English)

    Yang Peifeng; Zhang Jing; Yi Qiang; Fan Zerui; Li Jingchun; Yu Qi; Wang Xiangzhan; Yang Mohua; He Lin; Li Kaicheng; Tan Kaizhou; Liu Daoguang

    2002-01-01

    Based on theoretical analysis and computer-aided simulation, optimized design principles for Si/SiGe PMOSFET are given in this paper, which include choice of gate materials,determination of germanium percentage and profile in SiGe channel, optimization of thickness of dioxide and silicon cap layer, and adjustment of threshold voltage. In the light of these principles,a SiGe PMOSFET is designed and fabricated successfully. Measurement indicates that the SiGe PMOSFET's (L=2μm) transconductance is 45 mS/mm (300K) and 92mS/mm (77K), while that is 33 mS/mm (300K) and 39mS/mm (77K) in Si PMOSFET with the same structure.

  11. Atomistic simulation of damage accumulation and amorphization in Ge

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Selles, Jose L., E-mail: joseluis.gomezselles@imdea.org; Martin-Bragado, Ignacio [IMDEA Materials Institute, Eric Kandel 2, 28906 Getafe, Madrid (Spain); Claverie, Alain [CEMES/CNRS, 29 rue J. Marvig, 31055 Toulouse Cedex (France); Sklenard, Benoit [CEA, LETI, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Benistant, Francis [GLOBALFOUNDRIES Singapore Pte Ltd., 60 Woodlands Industrial Park D Street 2, Singapore 738406 (Singapore)

    2015-02-07

    Damage accumulation and amorphization mechanisms by means of ion implantation in Ge are studied using Kinetic Monte Carlo and Binary Collision Approximation techniques. Such mechanisms are investigated through different stages of damage accumulation taking place in the implantation process: from point defect generation and cluster formation up to full amorphization of Ge layers. We propose a damage concentration amorphization threshold for Ge of ∼1.3 × 10{sup 22} cm{sup −3} which is independent on the implantation conditions. Recombination energy barriers depending on amorphous pocket sizes are provided. This leads to an explanation of the reported distinct behavior of the damage generated by different ions. We have also observed that the dissolution of clusters plays an important role for relatively high temperatures and fluences. The model is able to explain and predict different damage generation regimes, amount of generated damage, and extension of amorphous layers in Ge for different ions and implantation conditions.

  12. Laser ablation and growth of Si and Ge

    Energy Technology Data Exchange (ETDEWEB)

    Yap, Seong Shan, E-mail: seong.yap@ntnu.no [Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Siew, Wee Ong; Nee, Chen Hon [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Reenaas, Turid Worren [Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Tou, Teck Yong [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia)

    2012-02-01

    In this work, we investigated the laser ablation and deposition of Si and Ge at room temperature in vacuum by employing nanosecond lasers of 248 nm, 355 nm, 532 nm and 1064 nm. Time-integrated optical emission spectra were obtained for neutrals and ionized Ge and Si species in the plasma at laser fluences from 0.5 to 11 J/cm{sup 2}. The deposited films were characterized by using Raman spectroscopy, scanning electron microscopy and atomic force microscopy. Amorphous Si and Ge films, micron-sized crystalline droplets and nano-sized particles were deposited. The results suggested that ionized species in the plasma promote the process of subsurface implantation for both Si and Ge films while large droplets were produced from the superheated and melted layer of the target. The dependence of the properties of the materials on laser wavelength and fluence were discussed.

  13. Aerial view of the 28 GeV Protron Synchrotron

    CERN Multimedia

    CERN PhotoLab

    1965-01-01

    The underground ring of the 28 GeV proton synchrotron in 1965. Left, the South and North experimental halls. Top right, part of the East hall. Bottom right, the main generator room and the cooling condensers.

  14. Growth strategies to control tapering in Ge nanowires

    Directory of Open Access Journals (Sweden)

    P. Periwal

    2014-04-01

    Full Text Available We report the effect of PH3 on the morphology of Au catalyzed Ge nanowires (NWs. Ge NWs were grown on Si (111 substrate at 400 °C in the presence of PH3, using vapor-liquid-solid method by chemical vapor deposition. We show that high PH3/GeH4 ratio causes passivation at NW surface. At high PH3 concentration phosphorous atoms attach itself on NW surface and form a self-protection coating that prevents conformal growth and leads to taper free nanostructures. However, in case of low PH3 flux the combination of axial and radial growth mechanism occurs resulting in conical structure. We have also investigated axial PH3-intrinsic junctions in Ge NWs. The unusual NW shape is attributed to a combination of catalyzed, uncatalyzed and diffusion induced growth.

  15. NQR study of chalcogenide glasses Ge-As-Se.

    Science.gov (United States)

    Glotova, Olga; Korneva, Irina; Sinyavsky, Nikolay; Ostafin, Michal; Nogaj, Boleslaw

    2011-07-01

    A three-component Ge-As-Se system is studied by the nuclear quadrupole resonance (NQR) method on (75)As nuclei and by the nutation NQR spectroscopy. The NQR (75)As spectra of the glasses Ge(0.021) As(0.375) Se(0.604), Ge(0.043) As(0.348) Se(0.609) and Ge(0.068) As(0.318) Se(0.614) reveal broad lines with two peaks assigned to the main structural unit of As(2)Se(3). With increasing average coordination number ( ̅r), the spectrum signals are shifted towards higher frequencies. At ̅r > 2.54, the spectrum becomes complex, which is a consequence of formation of more complex molecular structures in the glasses of high content of germanium. At fixed frequencies the asymmetry parameter η of the samples studied is determined.

  16. On the macroscopic formation length for GeV photons

    Energy Technology Data Exchange (ETDEWEB)

    Thomsen, H.D.; Esberg, J.; Kirsebom, K.; Knudsen, H.; Uggerhoj, E. [Department of Physics and Astronomy, University of Aarhus (Denmark); Uggerhoj, U.I. [Department of Physics and Astronomy, University of Aarhus (Denmark)], E-mail: ulrik@phys.au.dk; Sona, P. [University of Florence, Florence (Italy); Mangiarotti, A. [LIP, Universidade de Coimbra (Portugal); Ketel, T.J. [Free University, Amsterdam (Netherlands); Dizdar, A. [University of Istanbul, Istanbul (Turkey); Dalton, M.M.; Ballestrero, S.; Connell, S.H. [University of Johannesburg, Johannesburg (South Africa)

    2009-03-02

    Experimental results for the radiative energy loss of 206 and 234 GeV electrons in 5-10 {mu}m thin Ta targets are presented. An increase in radiation emission probability at low photon energies compared to a 100 {mu}m thick target is observed. This increase is due to the formation length of the GeV photons exceeding the thickness of the thin foils, the so-called Ternovskii-Shul'ga-Fomin (TSF) effect. The formation length of GeV photons from a multi-hundred GeV projectile is through the TSF effect shown directly to be a factor 10{sup 10} longer than their wavelength.

  17. 3 GeV RCS at the JKJ

    Science.gov (United States)

    Noda, Fumiaki

    2002-12-01

    3GeV RCS at the JAERI-KEK joint project (JKJ) is a rapid cycling synchrotron designed for high intensity proton beam. The designed output power is 1MW with a repetition rate of 25 Hz. In this paper, the outline of 3GeV RCS, key issues to achieve the goal, R&D status and time schedule of construction are reported.

  18. Tandlæge Lene Skak-Iversen

    DEFF Research Database (Denmark)

    Kjær, Inger

    2013-01-01

    Det var med stor sorg, at vi modtog meddelelsen om, at Lene Skak-Iversen var død efter kort tids sygdom, 66 år gammel. Dermed sluttede et fagligt enestående livsforløb, delt i tre forskellige perioder. Lene Skak-Iversen blev tandlæge i 1971. Hun fungerede i en årrække dels som børnetandlæge i Køb...

  19. Monolithically Integrated Ge-on-Si Active Photonics

    OpenAIRE

    Jifeng Liu

    2014-01-01

    Monolithically integrated, active photonic devices on Si are key components in Si-based large-scale electronic-photonic integration for future generations of high-performance, low-power computation and communication systems. Ge has become an interesting candidate for active photonic devices in Si photonics due to its pseudo-direct gap behavior and compatibility with Si complementary metal oxide semiconductor (CMOS) processing. In this paper, we present a review of the recent progress in Ge-on...

  20. On the DAMA and CoGeNT Modulations

    DEFF Research Database (Denmark)

    Frandsen, Mads Toudal; Kahlhoefer, Felix; March-Russell, John;

    2011-01-01

    DAMA observes an annual modulation in their event rate, as might be expected from dark matter scatterings, while CoGeNT has reported evidence for a similar modulation. The simplest interpretation of these findings in terms of dark matter-nucleus scatterings is excluded by other direct detection...... constraints, while inelasticity enhances the annual modulation fraction of the signal, bringing the CoGeNT and CDMS results into better agreement....

  1. Quantum devices using SiGe/Si heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Karunasiri, R.P.G.; Wang, K.L. (Univ. of California, Los Angeles (United States))

    Strained-layer Si{sub 1-x}Ge{sub x}/Si heterostructures have created a great deal of interest due to the potential of integration with the conventional silicon very large scale integrated technology. With the current advances in silicon molecular beam epitaxy (Si-MBE) and other low-temperature epitaxial techniques, many Si{sub 1-x}Ge{sub x}/Si heterojunction devices have been realized. For example, among those realized are avalanche photodiodes, modulation-doped field-effect transistors, heterojunction bipolar transistors, and more recently, resonant tunneling structures, hot-carrier transistors, and quantum well metal-oxide-semiconductor field-effect transistors. In this paper several quantum size effects in strained Si{sub 1-x}Ge{sub x} layers and their potential in device applications will be reviewed. Among those to be discussed are resonant tunneling, miniband transport, and intersubband absorption in Si{sub 1-x}Ge{sub x}/Si superlattice structures, optical properties of monolayer Si{sub m}Ge{sub n} superlattices, and observation of large Stark effect associated with interband transition between quantized states in Si{sub 1-x}Ge{sub x}/Si quantum well structures.

  2. Investigation of Room temperature Ferromagnetism in Mn doped Ge

    Science.gov (United States)

    Colakerol Arslan, Leyla; Toydemir, Burcu; Onel, Aykut Can; Ertas, Merve; Doganay, Hatice; Gebze Inst of Tech Collaboration; Research Center Julich Collaboration

    2014-03-01

    We present a systematic investigation of structural, magnetic and electronic properties of MnxGe1 -x single crystals. MnxGe1-x films were grown by sequential deposition of Ge and Mn by molecular-beam epitaxy at low substrate temperatures in order to avoid precipitation of ferromagnetic Ge-Mn intermetallic compounds. Reflected high energy electron diffraction and x-ray diffraction observations revealed that films are epitaxially grown on Si (001) substrates from the initial stage without any other phase formation. Magnetic measurements carried out using a physical property measurement system showed that all samples exhibited ferromagnetism at room temperature. Electron spin resonance indicates the presence of magnetically ordered localized spins of divalent Mn ions. X-ray absorption measurements at the Mn L-edge confirm significant substitutional doping of Mn into Ge-sites. The ferromagnetism was mainly induced by Mn substitution for Ge site, and indirect exchange interaction of these magnetic ions with the intrinsic charge carriers is the origin of ferromagnetism. The magnetic interactions were better understood by codoping with nonmagnetic impurities. This work was supported by Marie-Curie Reintegration Grant (PIRG08-GA-2010-276973).

  3. Pseudodynamic imaging of the temporomandibular joint: SE versus GE sequences

    Energy Technology Data Exchange (ETDEWEB)

    Masui, Takayuki; Isoda, Haruo; Mochizuki, Takao [Hamamatsu Univ. School of Medicine, Hamamatsu City (Japan)] [and others

    1996-05-01

    Pseudodynamic MR imaging of the temporomandibular joints (TMJs) has been used for the evaluation of the functional aspects of the TMJs. To evaluate the value of T1-weighted spin-echo (SE) and gradient-echo (GE) techniques, both techniques were performed in 9 asymptomatic (mean 25.7 years, 22-32 years), and 25 symptomatic (mean 44.9 years, 20-71 years) subjects with signs and symptoms of internal derangement or osteoarthrosis of the TMJs. The imaging time for the SE (180 ms / 15 ms / 110{degrees} repetition time / echo time /flip angle) and GE (fast low angle shot; FLASH, 90 ms / 12 ms / 40{degrees}) sequences was 27 and 28 s, respectively. In asymptomatic and symptomatic subjects, the confidence of the identification of the meniscal position was better on SE than GE images (3.6 {+-} 0.6 vs. 2.9 {+-} 0.9, p < 0.01, 3.2 {+-} 0.8 vs. 2.8 {+-} 0.8, p < 0.05), respectively and the sizes of the menisci were bigger on SE than GE images. The delineation of the condylar cortex was better on GE than SE images. For pseudodynamic imaging display of the TMJs, the SE images might be better than GE images to provide the stable recognition of the menisci. 17 refs., 7 figs., 5 tabs.

  4. Thermodynamic optimization of Co–Ge binary system

    Energy Technology Data Exchange (ETDEWEB)

    Dong, S.S.; Liu, S.G. [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); Tao, X.M. [College of Physical Science and Technology, Guangxi University, Nanning, Guangxi 530004 (China); Xiao, F.H.; Huang, L.H.; Yang, F.; He, Y.; Chen, Q. [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); Liu, H.S., E-mail: hsliu@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); Jin, Z.P. [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China)

    2013-11-20

    Graphical abstract: - Highlights: • The Co–Ge binary system was reassessed and optimized. • The first-principle approach was employed to calculate formation enthalpies of two compounds. • A self-consistent set of thermodynamic parameters was obtained. • The experimental data were well reproduced in the present optimization. - Abstract: Phase diagram of Co–Ge binary system was thermodynamically assessed by using CALPHAD approach in this study. The excess Gibbs energy of the solution phases, liquid, α(Co) and ε(Co), were modeled with Redlich–Kister polynomial. Magnetic contribution to the Gibbs energy was also taken into account for α(Co) and ε(Co). Considering its crystal structure and solubility range, the intermetallic compound βCo{sub 5}Ge{sub 3}, with B8{sub 2}-structure, was particularly described with a three-sublattice model, (Co,Va){sub 1}:(Co){sub 4}:(Co,Ge){sub 3}. And the compound CoGe was described with two-sublattice model according to its crystal structure. Other intermetallic compounds were described as stoichiometric phases because of their narrow homogeneity ranges or unknown crystal structure. In order to obtain a reasonable description of several Co–Ge compounds, first-principle calculations were performed before optimization to determine their formation enthalpies. Finally, a set of thermodynamic parameters was finally obtained so that most data of phase boundaries and thermodynamic properties of various phases were reproduced in present optimization.

  5. LArGe. A liquid argon scintillation veto for GERDA

    Energy Technology Data Exchange (ETDEWEB)

    Heisel, Mark

    2011-04-13

    LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the GERDA experiment. GERDA searches for the neutrinoless double-beta decay in {sup 76}Ge, by operating naked germanium detectors submersed into 65 m{sup 3} of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m{sup 3} (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used in anti-coincidence with the germanium detectors, to effectively suppress background events that deposit energy in the liquid argon. This work adresses the design, construction, and commissioning of LArGe. The background suppression efficiency has been studied in combination with a pulse shape discrimination (PSD) technique for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 10{sup 3} have been achieved. First background data of LArGe (without PSD) yield a background index of (0.12-4.6).10{sup -2} cts/(keV.kg.y) (90% c.l.), which is at the level of the Gerda phase I design goal. Furthermore, for the first time we measure the natural {sup 42}Ar abundance (in parallel to Gerda), and have indication for the 2{nu}{beta}{beta}-decay in natural germanium. (orig.)

  6. Research progress of self-organized Ge quantum dots on Si substrate

    Institute of Scientific and Technical Information of China (English)

    HUANG Changjun; YU Jinzhong; WANG Qiming

    2004-01-01

    A review is presented on recent research development of self-organized Ge/Si quantum dots (QDs).Emphasis is put on the morphological evolution of the Ge quantum dots grown on Si (001) substrate,the structure analysis of multilayer Ge QDs,the optical and electronic properties of these nanostructures,and the approaches to fabricating ordered Ge quantum dots.

  7. 77 FR 4587 - GE Asset Management Incorporated, et al.; Notice of Application and Temporary Order

    Science.gov (United States)

    2012-01-30

    ... Fund Service Activities. GE Funding CMS is an indirect, wholly-owned subsidiary of General Electric Company (``GE''), which also directly or indirectly wholly-owns the other Applicants. GE is a large and... any other company of which GE Funding CMS is or may become an affiliated person within the meaning...

  8. The 750 GeV Diphoton Excess May Not Imply a 750 GeV Resonance

    CERN Document Server

    Cho, Won Sang; Kong, Kyoungchul; Lim, Sung Hak; Matchev, Konstantin T; Park, Jong-Chul; Park, Myeonghun

    2015-01-01

    We discuss non-standard interpretations of the 750 GeV diphoton excess recently reported by the ATLAS and CMS Collaborations which do not involve a new, relatively broad, resonance with a mass near 750 GeV. Instead, we consider the sequential cascade decay of a much heavier, possibly quite narrow, resonance into two photons along with one or more invisible particles. The resulting diphoton invariant mass signal is generically rather broad, as suggested by the data. We examine three specific event topologies - the antler, the sandwich, and the 2-step cascade decay, and show that they all can provide a good fit to the observed published data. In each case, we delineate the preferred mass parameter space selected by the best fit. In spite of the presence of invisible particles in the final state, the measured missing transverse energy is moderate, due to its anti- correlation with the diphoton invariant mass. We comment on the future prospects of discriminating with higher statistics between our scenarios, as we...

  9. The JLab TMD Program at 6 GeV and 11 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Puckett, Andrew J. [Univ. of Connecticut, Storrs, CT (United States)

    2016-05-01

    The precise mapping of the nucleon’s transverse momentum dependent parton distributions (TMDs) in the valence quark region has emerged as one of the flagship physics programs of the recently upgraded Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab (JLab). The TMDs describe the three-dimensional, spin-correlated densities of quarks and gluons in the nucleon in momentum space, and are accessible experimentally through detailed studies of the Semi-Inclusive Deep Inelastic Scattering (SIDIS) process, N ( e ; e 0 h ) X . The already unrivaled intensity, polarization and duty factor performance of CEBAF will combine with the dramatic expansion of its kinematic reach embodied by the recent near-doubling of the maximum beam energy to enable the first fully differential precision measurements of SIDIS structure functions in the valence region. In this paper, I will review the existing and forthcoming SIDIS results from the 6 GeV era of CEBAF operations and present an overview of the planned JLab SIDIS program at 11 GeV beam energy

  10. Ferro electrical properties of GeSbTe thin films; Propiedades ferroelectricas de peliculas delgadas de GeSbTe

    Energy Technology Data Exchange (ETDEWEB)

    Gervacio A, J. J.; Prokhorov, E.; Espinoza B, F. J., E-mail: jgervacio@qro.cinvestav.m [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Juriquilla, 76230 Queretaro (Mexico)

    2011-07-01

    The aim of this work is to investigate and compare ferro electrical properties of thin GeSbTe films with composition Ge{sub 4}Sb{sub 1}Te{sub 5} (with well defined ferro electrical properties) and Ge{sub 2}Sb{sub 2}Te{sub 5} using impedance, optical reflection, XRD, DSc and Piezo response Force Microscopy techniques. The temperature dependence of the capacitance in both materials shows an abrupt change at the temperature corresponding to ferroelectric-paraelectric transition and the Curie-Weiss dependence. In Ge{sub 2}Sb{sub 2}Te{sub 5} films this transition corresponds to the end from a NaCl-type to a hexagonal transformation. Piezo response Force Microscopy measurements found ferroelectric domains with dimension approximately equal to the dimension of grains. (Author)

  11. Biaxial stress evaluation in GeSn film epitaxially grown on Ge substrate by oil-immersion Raman spectroscopy

    Science.gov (United States)

    Takeuchi, Kazuma; Suda, Kohei; Yokogawa, Ryo; Usuda, Koji; Sawamoto, Naomi; Ogura, Atsushi

    2016-09-01

    GeSn is being paid much attention as a next-generation channel material. In this work, we performed the excitation of forbidden transverse optical (TO) phonons from strained GeSn, as well as longitudinal optical (LO) phonons, under the backscattering geometry from the (001) surface by oil-immersion Raman spectroscopy. Using the obtained LO/TO phonons, we derived the phonon deformation potentials (PDPs), which play an important role in the stress evaluation, of the strained Ge1- x Sn x for the first time. The results suggest that PDPs are almost constant for the Ge1- x Sn x (x < 0.032). Biaxial stress calculated using the derived PDPs reasonably indicated the isotropic states.

  12. Role of Ge Switch in Phase Transition: Approach using Atomically Controlled GeTe/Sb2Te3 Superlattice

    Science.gov (United States)

    Tominaga, Juniji; Fons, Paul; Kolobov, Alexander; Shima, Takayuki; Chong, Tow Chong; Zhao, Rong; Koon Lee, Hock; Shi, Luping

    2008-07-01

    Germanium-antimony-tellurite (GST) is a very attractive material not only for rewritable optical media but also for realizing solid state devices. Recently, the study of the switching mechanism between the amorphous and crystal states has actively been carried out experimentally and theoretically. Now, the role of the flip-flop transition of a Ge atom in a distorted simple-cubic unit cell is the center of discussion. Turning our viewpoint towards a much wider region beyond a unit cell, we can understand that GeSbTe consists of two units: one is a Sb2Te3 layer and the other is a Ge2Te2 layer. On the based of this simple model, we fabricated the superlattice of GST alloys and estimated their thermal properties by differential scanning calorimetry (DSC). In this paper, we discuss the proof of the Ge switch on the basis of thermo-histories.

  13. Experiments and Modeling of Si-Ge Interdiffusion with Partial Strain Relaxation in Epitaxial SiGe Heterostructures

    KAUST Repository

    Dong, Y.

    2014-07-26

    Si-Ge interdiffusion and strain relaxation were studied in a metastable SiGe epitaxial structure. With Ge concentration profiling and ex-situ strain analysis, it was shown that during thermal anneals, both Si-Ge interdiffusion and strain relaxation occurred. Furthermore, the time evolutions of both strain relaxation and interdiffusion were characterized. It showed that during the ramp-up stage of thermal anneals at higher temperatures (800°C and 840°C), the degree of relaxation, R, reached a “plateau”, while interdiffusion was negligible. With the approximation that the R value is constant after the ramp-up stage, a quantitative interdiffusivity model was built to account for both the effect of strain relaxation and the impact of the relaxation induced dislocations, which gave good agreement with the experiment data.

  14. Closely packed Ge quantum dots in ITO matrix: influence of Ge crystallization on optical and electrical properties

    Science.gov (United States)

    Car, Tihomir; Nekić, Nikolina; Jerčinović, Marko; Salamon, Krešimir; Bogdanović-Radović, Iva; Delač Marion, Ida; Dasović, Jasna; Dražić, Goran; Ivanda, Mile; Bernstorff, Sigrid; Pivac, Branko; Kralj, Marko; Radić, Nikola; Buljan, Maja

    2016-06-01

    In the present work, a method for the low-temperature production of the material consisting of closely packed Ge QDs embedded in ITO matrix is described. The films are produced by magnetron sputtering deposition followed by thermal annealing. It is shown that the conductivity and optical properties of the films depend on the structure, Ge content in the ITO matrix as well as on the annealing conditions. The conductivity of the films changes up to seven orders of magnitude in dependence on the annealing conditions, and it shows transformation from semiconductor to metallic behavior. The optical properties are also strongly affected by the preparation and annealing conditions, so both conductivity and optical properties can be controllably manipulated. In addition, the crystallization of Ge is found to occur already at 300 °C, which is significantly lower than the crystallization temperature of Ge produced by the same method in silica and alumina matrices.

  15. Kesterite Cu2Zn(Sn,Ge)(S,Se)4 thin film with controlled Ge-doping for photovoltaic application

    Science.gov (United States)

    Zhao, Wangen; Pan, Daocheng; Liu, Shengzhong (Frank)

    2016-05-01

    Cu2ZnSn(S,Se)4 (CZTSSe) semiconductors have been a focus of extensive research effort owing to low-toxicity, high abundance and low material cost. Yet, the CZTSSe thin film solar cell has a low open-circuit voltage value that presents challenges. Herein, using GeSe2 as a new Ge source material, we have achieved a wider band gap CZTSSe-based semiconductor absorber layer with its band-gap controlled by adjusting the ratio of SnS2 : GeSe2 used. In addition, the Cu2Zn(Sn,Ge)(S,Se)4 thin films were prepared with optimal Ge doping (30%) and solar cells were fabricated to attain a respectable power conversion efficiency of 4.8% under 1.5 AM with an active area of 0.19 cm2 without an anti-reflection layer.Cu2ZnSn(S,Se)4 (CZTSSe) semiconductors have been a focus of extensive research effort owing to low-toxicity, high abundance and low material cost. Yet, the CZTSSe thin film solar cell has a low open-circuit voltage value that presents challenges. Herein, using GeSe2 as a new Ge source material, we have achieved a wider band gap CZTSSe-based semiconductor absorber layer with its band-gap controlled by adjusting the ratio of SnS2 : GeSe2 used. In addition, the Cu2Zn(Sn,Ge)(S,Se)4 thin films were prepared with optimal Ge doping (30%) and solar cells were fabricated to attain a respectable power conversion efficiency of 4.8% under 1.5 AM with an active area of 0.19 cm2 without an anti-reflection layer. Electronic supplementary information (ESI) available: The XRD patterns, chemical component analysis, top-view and cross-sectional images, and XPS of CZTGSSe thin films with different Ge content are exhibited. See DOI: 10.1039/c6nr00959j

  16. Local Structure of Ge/Si(100) Self-Assembled Quantum Dot

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Local structure of uncapped and Si-capped Ge quantum dots grownon Si(100) has been probed by X-ray absorption fine structure spectroscopy. It is found that the uncapped Ge dots are partially oxidized and partially alloyed with Si. The amount of Ge present in the Ge phase is found to be about 20-30%. In the Si-capped sample, Ge is found to be dissolved in silicon, the fraction of Ge atoms existing as pure Ge phase being not more than 10%.

  17. Properties of Si{sub n}, Ge{sub n}, and Si{sub n}Ge{sub n} clusters

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Yi; Rehman, Habib ur; Springborg, Michael [Physical and Theoretical Chemistry, University of Saarland, 66123 Saarbrücken (Germany)

    2015-01-22

    The structures of Si{sub n}, Ge{sub n}, and Si{sub n}Ge{sub n} clusters with up to 44 atoms have been determined theoretically using an unbiased structure-optimization method in combination with a parametrized, density-functional description of the total energy for a given structure. By analyzing the total energy in detail, particularly stable clusters are identified. Moreover, general trends in the structures are identified with the help of specifically constructed descriptors.

  18. Performance of a magnetized total absorption calorimeter between 15 GeV and 140 GeV

    CERN Document Server

    Holder, M; Devaux, B; Dorth, W; Dydak, F; Eisele, F; Flottmann, T; Geweniger, C; Grimm, M; Hepp, V; Kleinknecht, K; Knobloch, J; Maillard, J; May, J; Navarria, Francesco Luigi; Paar, H P; Palazzi, P; Peyaud, B; Rander, J; Savoy-Navarro, A; Schlatter, W D; Spahn, G; Steinberger, J; Suter, H; Tittel, K; Turlay, René; Wahl, H; Williams, E G H; Willutzki, H J; Wotschack, J

    1978-01-01

    The authors have calibrated a magnetized iron-scintillator sandwich calorimeter in a hadron beam, finding an energy resolution equal to 16% fwhm at 140 GeV with 4 cm sampling. The hadron energy resolution (fwhm/mean) improves as E/sup -1/2/ between 15 and 140 GeV. No effect due to the magnetic field was observed. Longitudinal and lateral shower containment were also investigated. (15 refs).

  19. Radiation from 170 GeV electrons and positrons traversing thin Si and Ge crystals near the <110> axis

    Energy Technology Data Exchange (ETDEWEB)

    Bak, J.F.; Moeller, S.P.; Petersen, J.B.B.; Soerensen, A.H.; Uggerhoej, E.; Barberis, D.; Elsener, K.; Brodbeck, T.J.; Newton, D.; Wilson, G.W.

    1988-10-20

    The first results from a broad angular beam experiment on emission of high-energy photons from 170 GeV electrons and positrons are presented. The targets were 0.5 mm thick Si and Ge crystals. A dramatic enhancement in the emitted radiation is found for angles of incidence close to the <110> axis. The experimental results are compared to a constant-field cascade calculation.

  20. Insights into microstructural evolution and polycrystalline compounds formation from Pd Ge thin films

    Science.gov (United States)

    Chen, Zhiwen; Shek, C. H.; Lai, J. K. L.

    2005-04-01

    Polycrystalline Pd-Ge thin films, prepared on freshly cleaved single crystal NaCl (1 0 0) substrate by evaporation techniques, were characterized for their composition, morphologies, and crystalline structure by transmission electron microscopy (TEM). The experimental results indicated that the formation of Pd 2Ge and PdGe compounds dominated at low annealing temperatures, and it also affected the crystallization of amorphous Ge. The reactions of Pd and Ge are sensitively dependent on the annealing temperatures and the thickness ratio of Pd and Ge films. The crystallization of amorphous Ge and the reactions of Pd and Ge are mutually competitive in polycrystalline Pd-Ge thin films. The grain nucleation, growth, and aggregation in Pd-Ge thin films during processing are discussed in terms of the fundamental kinetic processes.

  1. Insights into microstructural evolution and polycrystalline compounds formation from Pd-Ge thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zhiwen [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)]. E-mail: cnzwchen@yahoo.com.cn; Shek, C.H. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China); Lai, J.K.L. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)

    2005-04-15

    Polycrystalline Pd-Ge thin films, prepared on freshly cleaved single crystal NaCl (1 0 0) substrate by evaporation techniques, were characterized for their composition, morphologies, and crystalline structure by transmission electron microscopy (TEM). The experimental results indicated that the formation of Pd{sub 2}Ge and PdGe compounds dominated at low annealing temperatures, and it also affected the crystallization of amorphous Ge. The reactions of Pd and Ge are sensitively dependent on the annealing temperatures and the thickness ratio of Pd and Ge films. The crystallization of amorphous Ge and the reactions of Pd and Ge are mutually competitive in polycrystalline Pd-Ge thin films. The grain nucleation, growth, and aggregation in Pd-Ge thin films during processing are discussed in terms of the fundamental kinetic processes.

  2. The rotational spectra, potential function, Born-Oppenheimer breakdown, and hyperfine structure of GeSe and GeTe

    Science.gov (United States)

    Giuliano, Barbara M.; Bizzocchi, Luca; Sanchez, Raquel; Villanueva, Pablo; Cortijo, Vanessa; Sanz, M. Eugenia; Grabow, Jens-Uwe

    2011-08-01

    The pure rotational spectra of 18 and 21 isotopic species of GeSe and GeTe have been measured in the frequency range 5-24 GHz using a Fabry-Pérot-type resonator pulsed-jet Fourier-transform microwave spectrometer. Gaseous samples of both chalcogenides were prepared by a combined dc discharge/laser ablation technique and stabilized in supersonic jets of Ne. Global multi-isotopologue analyses of the derived rotational data, together with literature high-resolution infrared data, produced very precise Dunham parameters, as well as rotational constant Born-Oppenheimer breakdown (BOB) coefficients (δ01) for Ge, Se, and Te. A direct fit of the same datasets to an appropriate radial Hamiltonian yielded analytic potential-energy functions and BOB radial functions for the X1Σ+ electronic state of both GeSe and GeTe. Additionally, the electric quadrupole and magnetic hyperfine interactions produced by the nuclei 73Ge, 77Se, and 125Te were observed, yielding much improved quadrupole coupling constants and first determinations of the spin-rotation parameters.

  3. Hydrostatic strain enhancement in laterally confined SiGe nanostripes

    Science.gov (United States)

    Vanacore, G. M.; Chaigneau, M.; Barrett, N.; Bollani, M.; Boioli, F.; Salvalaglio, M.; Montalenti, F.; Manini, N.; Caramella, L.; Biagioni, P.; Chrastina, D.; Isella, G.; Renault, O.; Zani, M.; Sordan, R.; Onida, G.; Ossikovski, R.; Drouhin, H.-J.; Tagliaferri, A.

    2013-09-01

    Strain engineering in SiGe nanostructures is fundamental for the design of optoelectronic devices at the nanoscale. Here we explore a new strategy, where SiGe structures are laterally confined by the Si substrate, to obtain high tensile strain yet avoid the use of external stressors, thus improving the scalability. Spectromicroscopy techniques, finite element method simulations, and ab initio calculations are used to investigate the strain state of laterally confined Ge-rich SiGe nanostripes. Strain information is obtained by tip-enhanced Raman spectroscopy with an unprecedented lateral resolution of ˜30 nm. The nanostripes exhibit a large tensile hydrostatic strain component, which is maximal at the center of the top free surface and becomes very small at the edges. The maximum lattice deformation is larger than the typical values of thermally relaxed Ge/Si(001) layers. This strain enhancement originates from a frustrated relaxation in the out-of-plane direction, resulting from the combination of the lateral confinement induced by the substrate side walls and the plastic relaxation of the misfit strain in the (001) plane at the SiGe/Si interface. The effect of this tensile lattice deformation at the stripe surface is probed by work function mapping, which is performed with a spatial resolution better than 100 nm using x-ray photoelectron emission microscopy. The nanostripes exhibit a positive work function shift with respect to a bulk SiGe alloy, quantitatively confirmed by electronic structure calculations of tensile-strained configurations. The present results have a potential impact on the design of optoelectronic devices at a nanometer-length scale.

  4. Effects of Ge-132 and GeO2 on seed germination and seedling growth of Oenothera biennis L. under NaCl stress.

    Science.gov (United States)

    Liu, Yan; Hou, Long-Yu; Li, Qing-Mei; Jiang, Ze-Ping; Gao, Wei-Dong; Zhu, Yan; Zhang, Hai-Bo

    2017-01-01

    To investigate the effects of β-carboxyethyl germanium sequioxide (Ge-132) and germanium dioxide (GeO2) on improving salt tolerance of evening primrose (Oenothera biennis L.), seed germination, seedling growth, antioxidase and malondialdehyde (MDA) were observed under treatments of various concentrations (0, 5, 10, 20, 30 μM) of Ge in normal condition and in 50 mM NaCl solution. The results showed that both Ge-132 and GeO2 treatments significantly increased seed germination percentage and shoot length in dose-dependent concentrations but inhibited early root elongation growth. 5-30 μM Ge-132 and 10, 20 μM GeO2 treatments could significantly mitigate even eliminate harmful influence of salt, representing increased percentage of seed germination, root length, ratio between length of root and shoot, and decreased shoot length. These treatments also significantly decreased peroxidase (POD) and catalase (CAT) activities and MDA content. The mechanism is likely that Ge scavenges reactive oxygen species - especially hydrogen peroxide (H2O2) - by its electron configuration 4S(2)4P(2) so as to reduce lipid peroxidation. This is the first report about the comparison of bioactivity effect of Ge-132 and GeO2 on seed germination and seedling growth under salt stress. We conclude that Ge-132 is better than GeO2 on promoting salt tolerance of seed and seedling.

  5. High quality Ge epilayer on Si (1 0 0) with an ultrathin Si1-x Ge x /Si buffer layer by RPCVD

    Science.gov (United States)

    Chen, Da; Guo, Qinglei; Zhang, Nan; Xu, Anli; Wang, Bei; Li, Ya; Wang, Gang

    2017-07-01

    The authors report a method to grow high quality strain-relaxed Ge epilayer on a combination of low temperature Ge seed layer and Si1-x Ge x /Si superlattice buffer layer by reduced pressure chemical vapor deposition system without any subsequent annealing treatment. Prior to the growth of high quality Ge epilayer, an ultrathin Si1-x Ge x /Si superlattice buffer layer with the thickness of 50 nm and a 460 nm Ge seed layer were deposited successively at low temperature. Then an 840 nm Ge epilayer was grown at high deposition rate with the surface root-mean-square roughness of 0.707 nm and threading dislocation density of 2.5  ×  106 cm-2, respectively. Detailed investigations of the influence of ultrathin low-temperature Si1-x Ge x /Si superlattice buffer layer on the quality of Ge epilayer were performed, which indicates that the crystalline quality of Ge epilayer can be significantly improved by enhancing the Ge concentration of Si1-x Ge x /Si superlattice buffer layer.

  6. Very low-temperature epitaxial growth of Mn{sub 5}Ge{sub 3} and Mn{sub 5}Ge{sub 3}C{sub 0.2} films on Ge(111) using molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Petit, Matthieu, E-mail: matthieu.petit@univ-amu.fr [Aix-Marseille Université, CNRS, CINaM UMR 7325, 13288 Marseille (France); Michez, Lisa [Aix-Marseille Université, CNRS, CINaM UMR 7325, 13288 Marseille (France); Dutoit, Charles-Emmanuel; Bertaina, Sylvain; Dolocan, Voicu O. [Aix-Marseille Université, CNRS, IM2NP UMR7334, 13397 Cedex 20 Marseille (France); Heresanu, Vasile [Aix-Marseille Université, CNRS, CINaM UMR 7325, 13288 Marseille (France); Stoffel, Mathieu [Université de Lorraine, UMR CNRS 7198, Institut Jean Lamour, BP 70239, 54506 Vandeuvre-lès-Nancy (France); Le Thanh, Vinh [Aix-Marseille Université, CNRS, CINaM UMR 7325, 13288 Marseille (France)

    2015-08-31

    C-doped Mn{sub 5}Ge{sub 3} compound is ferromagnetic at temperature up to 430 K. Hence it is a potential spin injector into group-IV semiconductors. Segregation and diffusion of Mn at the Mn{sub 5}Ge{sub 3}/Ge interface could severely hinder the efficiency of the spin injection. To avoid these two phenomena we investigate the growth of Mn{sub 5}Ge{sub 3} and C-doped Mn{sub 5}Ge{sub 3} films on Ge(111) substrates by molecular beam epitaxy at room-temperature. The reactive deposition epitaxy method is used to deposit these films. Reflection high energy electron diffraction, X-ray diffraction analysis, transmission electron microscopy and atomic force microscopy indicate that the crystalline quality is very high. Magnetic characterizations by superconducting quantum interference device and ferromagnetic resonance reinforce the structural analysis results on the thin film quality. - Highlights: • Epitaxial Mn{sub 5}Ge{sub 3} and C-doped Mn{sub 5}Ge{sub 3} films grown on Ge(111) at room temperature. • Mn{sub 5}Ge{sub 3} and C-doped Mn{sub 5}Ge{sub 3} films grown by reactive deposition epitaxy. • RHEED, XRD and TEM measurements show a very high crystallinity. • Magnetic measurements support the structural analysis in the crystalline quality. • Ferromagnetic resonance linewidth is very narrow (3.5 mT at RT)

  7. Formation of Ge{sup 0} and GeO{sub x} nanoclusters in Ge{sup +}-implanted SiO{sub 2}/Si thin-film heterostructures under rapid thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Zatsepin, A.F., E-mail: a.f.zatsepin@urfu.ru [Institute of Physics and Technology, Ural Federal University, Mira Str. 19, 620002 Yekaterinburg (Russian Federation); Zatsepin, D.A. [Institute of Physics and Technology, Ural Federal University, Mira Str. 19, 620002 Yekaterinburg (Russian Federation); Institute of Metal Physics, Russian Academy of Sciences – Ural Division, S. Kovalevskoi Str. 18, 620990 Yekaterinburg (Russian Federation); Institute of Physics, Polish Academy of Science, 02-668 Warsaw (Poland); Zhidkov, I.S. [Institute of Physics and Technology, Ural Federal University, Mira Str. 19, 620002 Yekaterinburg (Russian Federation); Kurmaev, E.Z. [Institute of Physics and Technology, Ural Federal University, Mira Str. 19, 620002 Yekaterinburg (Russian Federation); Institute of Metal Physics, Russian Academy of Sciences – Ural Division, S. Kovalevskoi Str. 18, 620990 Yekaterinburg (Russian Federation); Fitting, H.-J. [Institute of Physics, University of Rostock, D-18051 Rostock (Germany); Schmidt, B. [Institute of Ion Beam Physics, Research Center Dresden-Rossendorf, POB 510119, 01314 Dresden (Germany); Mikhailovich, A.P. [Institute of Physics and Technology, Ural Federal University, Mira Str. 19, 620002 Yekaterinburg (Russian Federation); Lawniczak-Jablonska, K. [Institute of Physics, Polish Academy of Science, 02-668 Warsaw (Poland)

    2015-09-15

    Highlights: • Results of XPS for valence and core levels of Ge implanted SiO{sub 2} films are presented. • Chemical-state transformation of the host-matrix composition and Ge ions is performed. • The rapid thermal annealing strongly affects the oxidation states of Ge-atoms. • The formation of Ge{sup 0} and GeO{sub x} clusters within subsurface layer is observed. - Abstract: The results of X-ray photoelectron spectra (XPS valence band and core levels) measurements for Ge{sup +} implanted SiO{sub 2}/Si heterostructures are presented. These heterostructures have a 30 nm thick Ge{sup +} ion implanted amorphous SiO{sub 2} layer on p-type Si. The chemical-state transformation of the host-matrix composition after Ge{sup +} ion implantation and rapid thermal annealing (RTA) are discussed. The XPS-analysis performed allows to conclude the formation of Ge{sup 0} and GeO{sub x} clusters within the samples under study. It was established, that the annealing time strongly affects the degree of oxidation states of Ge-atoms.

  8. Theoretical Investigations of Si-Ge Alloys in P42/ncm Phase: First-Principles Calculations

    Science.gov (United States)

    Ma, Zhenyang; Liu, Xuhong; Yu, Xinhai; Shi, Chunlei; Yan, Fang

    2017-01-01

    The structural, mechanical, anisotropic, electronic and thermal properties of Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase are investigated in this work. The calculations have been performed with an ultra-soft pseudopotential by using the generalized gradient approximation and local density approximation in the framework of density functional theory. The achieved results for the lattice constants and band gaps of P42/ncm-Si and P42/ncm-Ge in this research have good accordance with other results. The calculated elastic constants and elastic moduli of the Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase are better than that of the Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/mnm phase. The Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase exhibit varying degrees of mechanical anisotropic properties in Poisson’s ratio, shear modulus, Young’s modulus, and universal anisotropic index. The band structures of the Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase show that they are all indirect band gap semiconductors with band gap of 1.46 eV, 1.25 eV, 1.36 eV and 1.00 eV, respectively. In addition, we also found that the minimum thermal conductivity κmin of the Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase exhibit different degrees of anisotropic properties in (001), (010), (100) and (01¯0) planes. PMID:28772964

  9. Theoretical Investigations of Si-Ge Alloys in P42/ncm Phase: First-Principles Calculations

    Directory of Open Access Journals (Sweden)

    Zhenyang Ma

    2017-05-01

    Full Text Available The structural, mechanical, anisotropic, electronic and thermal properties of Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase are investigated in this work. The calculations have been performed with an ultra-soft pseudopotential by using the generalized gradient approximation and local density approximation in the framework of density functional theory. The achieved results for the lattice constants and band gaps of P42/ncm-Si and P42/ncm-Ge in this research have good accordance with other results. The calculated elastic constants and elastic moduli of the Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase are better than that of the Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/mnm phase. The Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase exhibit varying degrees of mechanical anisotropic properties in Poisson’s ratio, shear modulus, Young’s modulus, and universal anisotropic index. The band structures of the Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase show that they are all indirect band gap semiconductors with band gap of 1.46 eV, 1.25 eV, 1.36 eV and 1.00 eV, respectively. In addition, we also found that the minimum thermal conductivity κmin of the Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase exhibit different degrees of anisotropic properties in (001, (010, (100 and (01¯0 planes.

  10. CV characteristics of polycrystalline sige films with low GE concentration

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Ricardo Cotrin [School of Electrical and Computer Engineering (FEEC) and Center for Semiconductor Components(CCS), State University of Campinas - UNICAMP, Cidade Universitaria Zeferino Vaz, Rua Pandia Calogeras, 90, Caixa Postal 6061, CEP: 13083-870, Campinas-SP (Brazil); Doi, Ioshiaki [School of Electrical and Computer Engineering (FEEC) and Center for Semiconductor Components(CCS), State University of Campinas - UNICAMP, Cidade Universitaria Zeferino Vaz, Rua Pandia Calogeras, 90, Caixa Postal 6061, CEP: 13083-870, Campinas-SP (Brazil)]. E-mail: doi@led.unicamp.br; Diniz, Jose Alexandre [School of Electrical and Computer Engineering (FEEC) and Center for Semiconductor Components(CCS), State University of Campinas - UNICAMP, Cidade Universitaria Zeferino Vaz, Rua Pandia Calogeras, 90, Caixa Postal 6061, CEP: 13083-870, Campinas-SP (Brazil); Swart, Jacobus Willibrordus [School of Electrical and Computer Engineering (FEEC) and Center for Semiconductor Components(CCS), State University of Campinas - UNICAMP, Cidade Universitaria Zeferino Vaz, Rua Pandia Calogeras, 90, Caixa Postal 6061, CEP: 13083-870, Campinas-SP (Brazil); Pinto Zakia, Maria Beny [Center for Semiconductor Components (CCS), State University of Campinas (UNICAMP), Cidade Universitaria Zeferino Vaz, Rua Pandia Calogeras, 90, Caixa Postal 6061, CEP: 13083-870, Campinas-SP (Brazil)

    2006-12-15

    SiGe alloys are currently used for HBT and MOS as epitaxial layers for base or strained channel, respectively. In the poly phase, SiGe has been studied as a replacement for poly-Si in MOS gates due to its lower thermal budget and gate depletion and also due to the Workfunction Engineering for V {sub t} adjustments. However, for application to CMOS technology as poly-SiGe gates, others constrains emerge such as quality of the oxide interface and etch chemistry. For both applications, the Ge fraction normally lies between 20% and 40%. In this study, authors use a low Ge contents (1%) poly-SiGe thin films aiming for MOS gate electrode. The Ge fraction was determined by RBS analysis. 230 nm thick samples were deposited onto 10 nm thermally oxidized <1 0 0>, p-type Si substrates using silane and germane. Films were deposited in the temperature of 500 deg. C and total pressure of 667 Pa (5 Torr) by vertical LPCVD. The samples were doped using {sup 31}P{sup +} ion implantation from 5 x 10{sup 14} cm{sup -2} up to 2 x 10{sup 16} cm{sup -2} and annealed by RTP (40 s) from 500 deg. C up to 900 deg. C. R {sub s} values were obtained by 4-point probe technique and CV curves were extracted from nMOS capacitors with 200 {mu}m diameter. The same processing steps were used to fabricate similar poly-Si samples and capacitors for comparison. The poly-SiGe samples presented R {sub s} values one order of magnitude lower than poly-Si and CV analysis of nMOS capacitors showed very good characteristics. The 1% Ge in the alloy ensures a low thermal budget for the overall process. Although a relatively high annealing temperature (800 deg. C) must be used to reduce oxide charge and interface traps, the temperature is well below the necessary for poly-Si processing and can allow formation of the shallow junctions needed for next technological nodes.

  11. Anisotropic phase separation through the metal-insulator transition in amorphous Mo-Ge and Fe-Ge alloys

    Energy Technology Data Exchange (ETDEWEB)

    Regan, M.J.

    1993-12-01

    Since an amorphous solid is often defined as that which lacks long-range order, the atomic structure is typically characterized in terms of the high-degree of short-range order. Most descriptions of vapor-deposited amorphous alloys focus on characterizing this order, while assuming that the material is chemically homogeneous beyond a few near neighbors. By coupling traditional small-angle x-ray scattering which probes spatial variations of the electron density with anomalous dispersion which creates a species-specific contrast, one can discern cracks and voids from chemical inhomogeneity. In particular, one finds that the chemical inhomogeneities which have been previously reported in amorphous Fe{sub x}Ge{sub 1-x} and Mo{sub x}Ge{sub 1-x} are quite anisotropic, depending significantly on the direction of film growth. With the addition of small amounts of metal atoms (x<0.2), no films appear isotropic nor homogeneous through the metal/insulator transition. The results indicate that fluctuations in the growth direction play a pivotal role in preventing simple growth models of a columnar structure or one that evolves systematically as it grows. The anomalous scattering measurements identify the metal atoms (Fe or Mo) as the source of the anisotropy, with the Ge atoms distributed homogeneously. The author has developed a method for using these measurements to determine the compositions of the phase-separating species. The results indicate phase separation into an amorphous Ge and an intermetallic phase of stoichiometry close to FeGe{sub 2} or MoGe{sub 3}. Finally, by manipulating the deposited power flux and rates of growth, Fe{sub x}Ge{sub 1-x} films which have the same Fe composition x can be grown to different states of phase separation. These results may help explain the difficulty workers have had in isolating the metal/insulator transition for these and other vapor-deposited amorphous alloys.

  12. Formation mechanisms of nano and microcones by laser radiation on surfaces of Si, Ge, and SiGe crystals.

    Science.gov (United States)

    Medvid, Artur; Onufrijevs, Pavels; Jarimaviciute-Gudaitiene, Renata; Dauksta, Edvins; Prosycevas, Igoris

    2013-06-04

    In this work we study the mechanisms of laser radiation interaction with elementary semiconductors such as Si and Ge and their solid solution SiGe. As a result of this investigation, the mechanisms of nanocones and microcones formation on a surface of semiconductor were proposed. We have shown the possibility to control the size and the shape of cones both by the laser. The main reason for the formation of nanocones is the mechanical compressive stresses due to the atoms' redistribution caused by the gradient of temperature induced by strongly absorbed laser radiation. According to our investigation, the nanocone formation mechanism in semiconductors is characterized by two stages. The first stage is characterized by formation of a p-n junction for elementary semiconductors or of a Ge/Si heterojunction for SiGe solid solution. The generation and redistribution of intrinsic point defects in elementary semiconductors and Ge atoms concentration on the irradiated surface of SiGe solid solution in temperature gradient field take place at this stage due to the thermogradient effect which is caused by strongly absorbed laser radiation. The second stage is characterized by formation of nanocones due to mechanical plastic deformation of the compressed Ge layer on Si. Moreover, a new 1D-graded band gap structure in elementary semiconductors due to quantum confinement effect was formed. For the formation of microcones Ni/Si structure was used. The mechanism of the formation of microcones is characterized by two stages as well. The first stage is the melting of Ni film after irradiation by laser beam and formation of Ni islands due to surface tension force. The second step is the melting of Ni and subsequent manifestations of Marangoni effect with the growth of microcones.

  13. MBE growth of Ge quantum dot structures in oxide windows

    Energy Technology Data Exchange (ETDEWEB)

    Karmous, A; Kirfel, O; Oehme, M; Kasper, E; Schulze, J, E-mail: karmous@iht.uni-stuttgart.de [Institut fuer Halbleitertechnik - Universitaet Stuttgart, Pfaffenwaldring 47, D-70569 Stuttgart (Germany)

    2009-11-15

    The implementation of Quantum Dots (QDs) in devices allows novel electronic and opto-electronic functions. Strain driven Stranski-Krastanov growth mode enables the formation of nanometric islands (on wetting layer) whose density and geometry depend on growth conditions (temperature, rate) and surface structure (cleaning). The island positions are random. However, they can be influenced by surface patterning. In this work, the MBE growth of self-organized Ge QD structures in oxide windows is investigated. The studied Ge QD structures are composed by either a single Ge layer directly grown on a Si substrate, or double layer formed by a Ge QD layer on top of a Si buffer layer. Different surface preparation (dry etching with and without anisotropic wet etching) and cleaning (HF dip or RCA cleaning) schemes have been used. It is found that the cleaning and the Si buffer layer growth have strong influence on island nucleation. Preferred nucleation at the window edge and/or nucleation at the window center is observed under certain conditions. Interestingly, negligible influence (this is needed for most device works) is found only if Ge is grown directly on the RCA cleaned window.

  14. Structural study of Ge/GaAs thin films

    Science.gov (United States)

    Lazarov, V. K.; Lari, L.; Lytvyn, P. M.; Kholevchuk, V. V.; Mitin, V. F.

    2012-07-01

    Ge/GaAs heterostructure research is largely motivated by the application of this material in solar cells, metal-oxide-semiconductor field-effect transistors, mm-wave mixer diodes, temperature sensors and photodetectors. Therefore, understanding of how the properties of Ge/GaAs heterostructure depend on its preparation (growth) is of importance for various high-efficiency devices. In this work, by using thermal Ge evaporation on GaAs(100), we studied structural properties of these films as a function of the deposition rate. Film grains size and morphology show strong dependence of the deposition rate. Low deposition rates results in films with large crystal grains and rough surface. At high deposition rates films become flatter and their crystal grains size decreases, while at very high deposition rates films become amorphous. Cross-sectional TEM of the films show that the Ge films are granular single crystal epitaxially grown on GaAs. The Ge/GaAs interface is atomically abrupt and free from misfit dislocations. Stacking faults along the [111] directions that originate at the interface were also observed. Finally by using the Kelvin probe microscopy we show that work function changes are related to the grain structure of the film.

  15. Poly-SiGe for MEMS-above-CMOS sensors

    CERN Document Server

    Gonzalez Ruiz, Pilar; Witvrouw, Ann

    2014-01-01

    Polycrystalline SiGe has emerged as a promising MEMS (Microelectromechanical Systems) structural material since it provides the desired mechanical properties at lower temperatures compared to poly-Si, allowing the direct post-processing on top of CMOS. This CMOS-MEMS monolithic integration can lead to more compact MEMS with improved performance. The potential of poly-SiGe for MEMS above-aluminum-backend CMOS integration has already been demonstrated. However, aggressive interconnect scaling has led to the replacement of the traditional aluminum metallization by copper (Cu) metallization, due to its lower resistivity and improved reliability. Poly-SiGe for MEMS-above-CMOS sensors demonstrates the compatibility of poly-SiGe with post-processing above the advanced CMOS technology nodes through the successful fabrication of an integrated poly-SiGe piezoresistive pressure sensor, directly fabricated above 0.13 m Cu-backend CMOS. Furthermore, this book presents the first detailed investigation on the influence o...

  16. Ion implantation damage and crystalline-amorphous transition in Ge

    Energy Technology Data Exchange (ETDEWEB)

    Impellizzeri, G.; Mirabella, S.; Grimaldi, M.G. [Universita di Catania, MATIS IMM-CNR (Italy); Dipartimento di Fisica e Astronomia, Catania (Italy)

    2011-05-15

    Experimental studies on the damage produced in (100) Ge substrates by implantation of Ge{sup +} ions at different energies (from 25 to 600 keV), fluences (from 2 x 10{sup 13} to 4 x 10{sup 14} cm{sup -2}) and temperature (room temperature, RT, or liquid-nitrogen temperature, LN{sub 2}T) have been performed by using the Rutherford backscattering spectrometry technique. We demonstrated that the higher damage rate of Ge with respect to Si is due to both the high stopping power of germanium atoms and the low mobility of point defects within the collision cascades. The amorphization of Ge has been modeled by employing the critical damage energy density model in a large range of implantation energies and fluences both at RT and LN{sub 2}T. The experimental results for implantation at LN{sub 2}T were fitted using a critical damage energy density of {proportional_to}1 eV/atom. A fictitious value of {proportional_to}5 eV/atom was obtained for the samples implanted at RT, essentially because at RT the damage annihilation plays a non-negligible role against the crystalline-amorphous transition phase. The critical damage energy density model was found to stand also for other ions implanted in crystalline Ge (Ar{sup +} and Ga{sup +}). (orig.)

  17. A note on the reactions in the Ti-Ge system

    Directory of Open Access Journals (Sweden)

    Joshua Pelleg

    2012-09-01

    Full Text Available Formations of germanides in thin films of the Ti-Ge system were investigated by XRD after furnace annealing for 1 hour. Ti6Ge5 seems to be the first phase formed while TiGe2 is the end phase with the lowest resistivity. The existence of the phase Ti5Ge3 was confirmed which forms at higher temperatures than Ti6Ge5. The presence of a thin TiO2 layer was observed by TEM. Which of the phase exists or is missed depends on composition of the constituents comprising the film, their thickness and temperature of reaction. Three phases are observed to coexist on the Ge substrate, which are Ti5Ge3, Ti6Ge5 and TiGe2. A schematic suggestion is presented for explaining the coexistence of two or more phases. The concept of formation and coexistence of two phases at lower temperatures is also proposed.

  18. The origin of the resistance change in GeSbTe films

    Science.gov (United States)

    Jang, Moon Hyung; Park, Seung Jong; Park, Sung Jin; Cho, Mann-Ho; Kurmaev, E. Z.; Finkelstein, L. D.; Chang, Gap Soo

    2010-10-01

    Amorphous Ge2Sb2Te5 (a-GST) films were deposited by ion beam sputtering deposition. Extended x-ray absorption fine structure (EXAFS) data confirmed the existence of the Ge-Ge homopolar bonds in the films. Raman spectra also indicated that the Ge tetrahedral coordination in the a-GST film disappeared after an annealing treatment above 220 °C. Resonantly excited Ge L2,3 x-ray emission spectra (which probe occupied Ge 3d4s-electronic states) show that the phase change from the amorphous to crystalline state is accompanied by a reduction in the Ge I(L2)/I(L3) intensity ratio due to a L2L3N Coster-Kronig transition, indicating that the number of carriers is increased in the Ge 4sp valence state. These findings constitute direct evidence for the contribution of the Ge electronic states to the resistivity change.

  19. The microstructure of Ge/Si layers grown at low temperature

    Science.gov (United States)

    Roddatis, V. V.; Vasiliev, A. L.; Kovalchuk, M. V.

    2013-11-01

    Multilayer Si/Ge heterostructures with the thickness of Ge layers varying from 2 to 12 monolayers (ML) were formed by molecular beam epitaxy (MBE) on the (001) Si substrates at 300°C (Ge) and 450°C (Si). The study of the Si/Ge heterostructures was performed by transmission and Cs corrected scanning transmission electron microscopy (STEM). It was shown that the growth of Ge layers up to thickness of 5 ML occurs through the Frank - van der Merwe mechanism. For thicker Ge layers the growth mechanism of the Si-Ge heterostructure changes to Stranski - Krastanov with Si-Ge islands having the shape of inverted pyramids. The Si-Ge layer intermixing was discussed.

  20. Magnetic ordering of Hf3Ni2Si3-type {Sm, Tb, Er}3Co2Ge3 and {Tb, Ho}3Ni2Ge3 compounds

    Science.gov (United States)

    Morozkin, A. V.; Yapaskurt, V. O.; Nirmala, R.; Quezado, S.; Malik, S. K.; Mozharivskyj, Y.; Isnard, O.

    2017-02-01

    The magnetic ordering of Hf3Ni2Si3-type {Sm, Tb, Er}3Co2Ge3 and {Tb, Ho}3Ni2Ge3 compounds (space group Cmcm, oC32) was investigated via magnetization measurements and neutron diffraction study in a zero-applied field. {Sm, Tb, Er}3Co2Ge3 and Ho3Ni2Ge3 exhibit field sensitive complex antiferromagnetic orderings with TN=51 K, Tm=10 K for Sm3Co2Ge3, TN=34 K, Tm=13 K for Tb3Co2Ge3, TN=7 K for Er3Co2Ge3 and TN=11 K for Ho3Ni2Ge3. At 2 K and above the critical field of 5 kOe, 20 kOe, 4 kOe and 7 kOe for Sm3Co2Ge3, Tb3Co2Ge3, Er3Co2Ge3 and Ho3Ni2Ge3, respectively, saturation magnetizations per rare-earth atom are 6.5 μB for Tb3Co2Ge3, 7.0 μB for Er3Co2Ge3 and 8.0 μB for Ho3Ni2Ge3 in the field of 140 kOe, whereas magnetization of Sm3Co2Ge3 has an antiferromagnetic behaviour. The isothermal magnetic entropy change, ΔSm, indicates a field-induced ferromagnetic ordering in Sm3Co2Ge3, Tb3Co2Ge3, Er3Co2Ge3 and Ho3Ni2Ge3 with a maximal ΔSm value of -10.9 J/kg K for Ho3Ni2Ge3 at 11 K for a field change of 50 kOe. In a zero-applied magnetic field, below TN=33 K and down to TmND=15 K Tb3Ni2Ge3 shows an ac-antiferromagnetic ordering with the C2‧/c magnetic space group, a K0=[0, 0, 0] propagation vector and a aTb3Ni2Ge3×bTb3Ni2Ge3×cTb3Ni2Ge3 magnetic unit cell. Below TmND=15 K, its magnetic structure is a sum of the ac-antiferromagnetic component with the C2‧/c magnetic space group of the K0 vector and a sine-modulated a-antiferromagnetic component of the K1=[0, 0, ±1/3] propagation vector (the magnetic unit cell is aTb3Ni2Ge3×bTb3Ni2Ge3×3cTb3Ni2Ge3). The magnetic structure is made from the 'Tb2 - 2Tb1‧ clusters of the Tb1 8f and Tb2 4c sublattices with a dominant role of the Tb2 sublattices in the magnetic ordering of Tb3Ni2Ge3.

  1. Growth mechanism of Ge-doped CZTSSe thin film by sputtering method and solar cells.

    Science.gov (United States)

    Li, Jinze; Shen, Honglie; Chen, Jieyi; Li, Yufang; Yang, Jiale

    2016-10-19

    Ge-doped CZTSSe thin films were obtained by covering a thin Ge layer on CZTS precursors, followed by a selenization process. The effect of the Ge layer thickness on the morphologies and structural properties of Ge-doped CZTSSe thin films were studied. It was found that Ge doping could promote grain growth to form a compact thin film. The lattice shrank in the top-half of the film due to the smaller atomic radius of Ge, leading to the formation of tensile stress. According to thermodynamic analysis, Sn was easier to be selenized than Ge. Thus, Ge preferred to remain on the surface and increased the surface roughness when the Ge layer was thin. CZTSe was easier to form than Ge-doped CZTSe, which caused difficulty in Ge doping. These results offered a theoretical and experimental guide for preparing Ge-doped CZTSSe thin films for the potential applications in low-cost solar cells. With a 10 nm Ge layer on the top of the precursor, the conversion efficiency of the solar cell improved to 5.38% with an open-circuit voltage of 403 mV, a short-circuit current density of 28.51 mA cm(-2) and a fill factor of 46.83% after Ge doping.

  2. Generation of AuGe nanocomposites by co-sparking technique and their photoluminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Kala, Shubhra, E-mail: shubkala@gmail.com [National Physical Laboratory (India); Theissmann, Ralf; Kruis, Frank Einar [University of Duisburg-Essen, Institute for Nanostructures and Technology, Faculty of Engineering Science, and CENIDE (Center for Nanointegration Duisburg-Essen) (Germany)

    2013-09-15

    The feasibility of spark discharge technique for preparing metal-semiconductor nanocomposites is demonstrated. In the AuGe system, Au shows only 10{sup -3} atomic percent solid solubility in Ge, whereas 3.1 at.% Ge is soluble in Au. During the co-sparking, Au is used as anode material; the cathode is composed of Ge. The relative atomic percent of Au and Ge in the initially generated mixture can be changed by changing the charging current to the capacitor used to trigger the sparking. Depending upon the atomic ratio of Au and Ge in the initial mixture, AuGe agglomerates form AuGe composite nanoparticles on subsequent sintering, in which AuGe alloy nanoparticles are found dispersed in a Ge matrix. The size of the dispersed AuGe alloy nanoparticles depend on the relative atomic concentration of Au and Ge in the initial mixture as well as on the sintering temperature. AuGe alloy nanoparticles dispersed in the Ge matrix are observed to exhibit an intense photoluminescence between 550 and 600 nm.

  3. Structural and magnetic properties of GeMn layers; High Curie temperature ferromagnetism induced by self organized GeMn nano-columns

    Energy Technology Data Exchange (ETDEWEB)

    Devillers, T.; Jamet, M.; Barski, A.; Poydenot, V.; Dujardin, R.; Bayle Guillemaud, P.; Bellet Amalric, E.; Mattana, R. [Departement de Recherche Fondamentale sur la Matiere Condensee, Service de Physique des Materiaux et Microstructures, CEA Grenoble, 17 avenue des Martyrs, 38054 Grenoble Cedex (France); Rothman, J. [Laboratoire d' Electronique de Technologie de l' Information, Laboratoire Infrarouge, CEA Grenoble, 17 avenue des Martyrs, 38054 Grenoble Cedex (France); Cibert, J. [Laboratoire Louis Neel, CNRS, BP166, 38042 Grenoble Cedex 9 (France); Tatarenko, S. [Laboratoire de Spectrometrie Physique, BP 87, 38402 Saint-Martin d' Heres (France)

    2007-01-15

    In this paper we report on the structural and magnetic properties of GeMn layers grown on Ge(001). We show that for the optimized Mn concentration (6%) and for optimized growth temperature (close to 130 C), GeMn samples exhibit a high Curie temperature (higher than 400 K) and Anomalous Hall Effect up to room temperature. Our GeMn layers grown at low temperature (70 C to 130 C) are composed of vertical Mn-rich nano-columns. Samples grown at temperatures higher than 130 C contain GeMn nanoclusters. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Collectivity at N=50: 82Ge and 84Se

    CERN Document Server

    Gade, A; Bazin, D; Brown, B A; Campbell, C M; Glasmacher, T; Grinyer, G F; Honma, M; McDaniel, S; Meharchand, R; Otsuka, T; Ratkiewicz, A; Tostevin, J A; Walsh, K A; Weisshaar, D

    2010-01-01

    The neutron-rich N=50 isotones 82Ge and 84Se were investigated using intermediate-energy Coulomb excitation on a 197Au target and inelastic scattering on 9Be. As typical for intermediate-energy Coulomb excitation with projectile energies exceeding 70 MeV/nucleon, only the first 2^+ states were excited in 82Ge and 84Se. However, in the inelastic scattering on a 9Be target, a strong population of the first 4^+ state was observed for 84Se, while there is no indication of a similarly strong excitation of the corresponding state in the neighboring even-even isotone 82Ge. The results are discussed in the framework of systematics and shell-model calculations using three different effective interactions.

  5. Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions.

    Science.gov (United States)

    Zhang, Kun; Li, Huan-Huan; Grünberg, Peter; Li, Qiang; Ye, Sheng-Tao; Tian, Yu-Feng; Yan, Shi-Shen; Lin, Zhao-Jun; Kang, Shi-Shou; Chen, Yan-Xue; Liu, Guo-Lei; Mei, Liang-Mo

    2015-09-21

    Magnetoresistance and rectification are two fundamental physical properties of heterojunctions and respectively have wide applications in spintronics devices. Being different from the well known various magnetoresistance effects, here we report a brand new large magnetoresistance that can be regarded as rectification magnetoresistance: the application of a pure small sinusoidal alternating-current to the nonmagnetic Al/Ge Schottky heterojunctions can generate a significant direct-current voltage, and this rectification voltage strongly varies with the external magnetic field. We find that the rectification magnetoresistance in Al/Ge Schottky heterojunctions is as large as 250% at room temperature, which is greatly enhanced as compared with the conventional magnetoresistance of 70%. The findings of rectification magnetoresistance open the way to the new nonmagnetic Ge-based spintronics devices of large rectification magnetoresistance at ambient temperature under the alternating-current due to the simultaneous implementation of the rectification and magnetoresistance in the same devices.

  6. A New 76Ge Double Beta Decay Experiment at LNGS

    CERN Document Server

    Abt, I; Bakalyarov, A; Barabanov, I; Bauer, C; Bellotti, E; Belyaev, S T; Bezrukov, L; Brudanin, V; Buettner, C; Bolotsky, V P; Caldwell, A; Cattadori, C; Clement, H; Vacri, A D; Eberth, J; Egorov, V; Grigoriev, G V; Gurentsov, V I; Gusev, K; Hampel, W; Heusser, G; Hofmann, W; Jochum, J; Junker, M; Kiko, J; Kirpichnikov, I V; Klimenko, A; Knöpfle, K T; Kornoukhov, V N; Laubenstein, M; Lebedev, V; Liu, X; Nemchenok, I B; Pandola, L; Sandukovsky, V; Schönert, S; Scholl, S; Schwingenheuer, B; Simgen, H; Smolnikov, A A; Tikhomirov, A; Vasenko, A A; Vasilev, S; Weisshaar, D; Yanovich, E A; Yurkovski, J; Zhukov, S; Zuzel, G

    2004-01-01

    This Letter of Intent has been submitted to the Scientific Committee of the INFN Laboratori Nazionali del Gran Sasso (LNGS) in March 2004. It describes a novel facility at the LNGS to study the double beta decay of 76Ge using an (optionally active) cryogenic fluid shield. The setup will allow to scrutinize with high significance on a short time scale the current evidence for neutrinoless double beta decay of 76Ge using the existing 76Ge diodes from the previous Heidelberg-Moscow and IGEX experiments. An increase in the lifetime limit can be achieved by adding more enriched detectors, remaining thereby background-free up to a few 100 kg-years of exposure.

  7. Electrical conduction mechanism in GeSeSb chalcogenide glasses

    Indian Academy of Sciences (India)

    Vandana Kumari; Anusaiya Kaswan; D Patidar; Kananbala Sharma; N S Saxena

    2016-02-01

    Electrical conductivity of chalcogenide glassy system Ge$_{30−x}$Se$_{70}$Sb$_{x}$ ( = 10, 15, 20 and 25) prepared by melt quenching has been determined at different temperatures in bulk through the $I$–$V$ characteristic curves. It is quite evident from results that Poole–Frenkel conduction mechanisms hold good for conduction in these glasses in a given temperature range. The variation in electrical conductivity with composition was attributed to the Se–Sb bond concentration in the Se–Ge–Sb system. Results indicated that Ge$_5$Se$_{70}$Sb$_{25}$ showed the minimum resistance. In view of this the composition Ge$_5$Se$_{70}$Sb$_{25}$ may be coined as ‘critical composition’ in the proposed series. Also the activation energies of conduction of these glassy alloys have been calculated in higher and lower temperature range using the Arrhenius equation.

  8. Study on Gd-Si-Ge Alloys Using Domestic Gd

    Institute of Scientific and Technical Information of China (English)

    吴卫; 卢定伟

    2004-01-01

    To evaluate the possibility of using Gd-Si-Ge alloys in magnetic refrigerators,samples of Gd-Si-Ge alloys were made of domestic Gd.The magnetocaloric effect of samples was estimated by magnetic entropy change (-ΔSm) calculated from M-H curves according to Maxwell relation.The first order phase transformation was destroyed due to the impurities in the commercial Gd,so that no giant magnetocaloric effect was found.The samples made of purified Gd exhibit first order phase transformation,and the -ΔSm is basically consistent with the published data of Ames laboratory,USA.This work proves that Gd-Si-Ge alloys made of domestic Gd can be utilized in magnetic refrigerators.

  9. S5 0716+714 : GeV variability study

    CERN Document Server

    Rani, B; Lott, B; Fuhrmann, L; Zensus, J A

    2013-01-01

    The GeV observations by Fermi-LAT give us the opportunity to characterize the high-energy emission (100 MeV - 300 GeV) variability properties of the BL Lac object S5 0716+714. In this study, we performed flux and spectral analysis of more than 3 year long (August 2008 to April 2012) Fermi-LAT data of the source. During this period, the source exhibits two different modes of flux variability with characteristic timescales of ~75 and ~140 days, respectively. We also notice that the flux variations are characterized by a weak spectral hardening. The GeV spectrum of the source shows a clear deviation from a simple power law, and is better explained by a broken power law. Similar to other bright Fermi blazars, the break energy does not vary with the source flux during the different activity states. We discuss several possible scenarios to explain the observed spectral break.

  10. Reducing 68Ge Background in Dark Matter Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kouzes, Richard T.; Orrell, John L.

    2011-03-01

    Experimental searches for dark matter include experiments with sub-0.5 keV-energy threshold high purity germanium detectors. Experimental efforts, in partnership with the CoGeNT Collaboration operating at the Soudan Underground Laboratory, are focusing on energy threshold reduction via noise abatement, reduction of backgrounds from cosmic ray generated isotopes, and ubiquitous environmental radioactive sources. The most significant cosmic ray produced radionuclide is 68Ge. This paper evaluates reducing this background by freshly mining and processing germanium ore. The most probable outcome is a reduction of the background by a factor of two, and at most a factor of four. A very cost effective alternative is to obtain processed Ge as soon as possible and store it underground for 18 months.

  11. Franz-Keldysh effect in GeSn pin photodetectors

    Energy Technology Data Exchange (ETDEWEB)

    Oehme, M., E-mail: oehme@iht.uni-stuttgart.de; Kostecki, K.; Schmid, M.; Kaschel, M.; Gollhofer, M.; Ye, K.; Widmann, D.; Koerner, R.; Bechler, S.; Kasper, E.; Schulze, J. [Institut für Halbleitertechnik, Universität Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart (Germany)

    2014-04-21

    The optical properties and the Franz-Keldysh effect at the direct band gap of GeSn alloys with Sn concentrations up to 4.2% at room temperature were investigated. The GeSn material was embedded in the intrinsic region of a Ge heterojunction photodetector on Si substrates. The layer structure was grown by means of ultra-low temperature molecular beam epitaxy. The absorption coefficient as function of photon energy and the direct bandgap energies were determined. In all investigated samples, the Franz-Keldysh effect can be observed. A maximum absorption ratio of 1.5 was determined for 2% Sn for a voltage swing of 3 V.

  12. Ge-on-Si laser operating at room temperature.

    Science.gov (United States)

    Liu, Jifeng; Sun, Xiaochen; Camacho-Aguilera, Rodolfo; Kimerling, Lionel C; Michel, Jurgen

    2010-03-01

    Monolithic lasers on Si are ideal for high-volume and large-scale electronic-photonic integration. Ge is an interesting candidate owing to its pseudodirect gap properties and compatibility with Si complementary metal oxide semiconductor technology. Recently we have demonstrated room-temperature photoluminescence, electroluminescence, and optical gain from the direct gap transition of band-engineered Ge-on-Si using tensile strain and n-type doping. Here we report what we believe to be the first experimental observation of lasing from the direct gap transition of Ge-on-Si at room temperature using an edge-emitting waveguide device. The emission exhibited a gain spectrum of 1590-1610 nm, line narrowing and polarization evolution from a mixed TE/TM to predominantly TE with increasing gain, and a clear threshold behavior.

  13. Reducing 68Ge Background in Dark Matter Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kouzes, Richard T.; Orrell, John L.

    2011-03-01

    Experimental searches for dark matter include experiments with sub-0.5 keV-energy threshold high purity germanium detectors. Experimental efforts, in partnership with the CoGeNT Collaboration operating at the Soudan Underground Laboratory, are focusing on energy threshold reduction via noise abatement, reduction of backgrounds from cosmic ray generated isotopes, and ubiquitous environmental radioactive sources. The most significant cosmic ray produced radionuclide is 68Ge. This paper evaluates reducing this background by freshly mining and processing germanium ore. The most probable outcome is a reduction of the background by a factor of two, and at most a factor of four. A very cost effective alternative is to obtain processed Ge as soon as possible and store it underground for 18 months.

  14. Characterising the 750 GeV diphoton excess

    Energy Technology Data Exchange (ETDEWEB)

    Bernon, Jérémy [Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS/IN2P3,53 Avenue des Martyrs, Grenoble, F-38026 (France); Goudelis, Andreas [Institute of High Energy Physics, Austrian Academy of Sciences,Nikolsdorfergasse 18, Vienna, 1050 (Austria); Kraml, Sabine [Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS/IN2P3,53 Avenue des Martyrs, Grenoble, F-38026 (France); Mawatari, Kentarou [Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS/IN2P3,53 Avenue des Martyrs, Grenoble, F-38026 (France); Theoretische Natuurkunde and IIHE/ELEM, Vrije Universiteit Brussel, and International Solvay Institutes, Pleinlaan 2, Brussels, B-1050 (Belgium); Sengupta, Dipan [Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS/IN2P3,53 Avenue des Martyrs, Grenoble, F-38026 (France)

    2016-05-23

    We study kinematic distributions that may help characterise the recently observed excess in diphoton events at 750 GeV at the LHC Run 2. Several scenarios are considered, including spin-0 and spin-2 750 GeV resonances that decay directly into photon pairs as well as heavier parent resonances that undergo three-body or cascade decays. We find that combinations of the distributions of the diphoton system and the leading photon can distinguish the topology and mass spectra of the different scenarios, while patterns of QCD radiation can help differentiate the production mechanisms. Moreover, missing energy is a powerful discriminator for the heavy parent scenarios if they involve (effectively) invisible particles. While our study concentrates on the current excess at 750 GeV, the analysis is general and can also be useful for characterising other potential diphoton signals in the future.

  15. The 6 GeV TMD Program at Jefferson Lab

    Energy Technology Data Exchange (ETDEWEB)

    Puckett, Andrew J. [Univ. of Connecticut, Storrs, CT (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2015-01-01

    The study of the transverse momentum dependent parton distributions (TMDs) of the nucleon in semi-inclusive deep-inelastic scattering (SIDIS) has emerged as one of the major physics motivations driving the experimental program using the upgraded 11 GeV electron beam at Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF). The accelerator construction phase of the CEBAF upgrade is essentially complete and commissioning of the accelerator has begun as of April, 2014. As the new era of CEBAF operations begins, it is appropriate to review the body of published and forthcoming results on TMDs from the 6 GeV era of CEBAF operations, discuss what has been learned, and discuss the key challenges and opportunities for the 11 GeV SIDIS program of CEBAF.

  16. Flat Ge-doped optical fibres for food irradiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Noor, N. Mohd; Jusoh, M. A. [Department of Imaging, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Razis, A. F. Abdull [Food Safety Research Centre, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Laboratory of UPM-MAKNA Cancer Research, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Alawiah, A. [Faculty of Engineering and Technology, Multimedia University, 75450 Malacca (Malaysia); Bradley, D. A. [Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-04-24

    Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dose response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%.

  17. CEBAF SRF Performance during Initial 12 GeV Commissioning

    Energy Technology Data Exchange (ETDEWEB)

    Bachimanchi, Ramakrishna; Allison, Trent; Daly, Edward; Drury, Michael; Hovater, J; Lahti, George; Mounts, Clyde; Nelson, Richard; Plawski, Tomasz

    2015-09-01

    The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of eleven new 100 MV cryomodules (88 cavities). The superconducting RF cavities are designed to operate CW at an accelerating gradient of 19.3 MV/m with a QL of 3×107. Not all the cavities were operated at the minimum gradient of 19.3 MV/m with the beam. Though the initial 12 GeV milestones were achieved during the initial commissioning of CEBAF, there are still some issues to be addressed for long term reliable operation of these modules. This paper reports the operational experiences during the initial commissioning and the path forward to improve the performance of C100 (100 MV) modules.

  18. Structure of a passivated Ge surface prepared from aqueous solution.

    Energy Technology Data Exchange (ETDEWEB)

    Lyman, P. F.; Sakata, O.; Marasco, D, L.; Lee, T.-L.; Breneman, K. D.; Keane, D. T.; Bedzyk, M. J.; Materials Science Division; Northwestern Univ.; Univ. of Wisconsin at Milwaukee

    2000-08-10

    The structure of a passivating sulfide layer on Ge(001) was studied using X-ray standing waves and X-ray fluorescence. The sulfide layer was formed by reacting clean Ge substrates in (NH{sub 4}){sub 2}S solutions of various concentrations at 80{sup o}C. For each treatment, a sulfide layer containing approximately two to three monolayers (ML) of S was formed on the surface, and an ordered structure was found at the interface that contained approximately 0.4 ML of S. Our results suggest the rapid formation of a glassy GeS{sub x} layer containing 1.5-2.5 ML S residing atop a partially ordered interfacial layer of bridge-bonded S. The passivating reaction appears to be self-limited to 2-3 ML at this reaction temperature.

  19. Characterising the 750 GeV diphoton excess

    Science.gov (United States)

    Bernon, Jérémy; Goudelis, Andreas; Kraml, Sabine; Mawatari, Kentarou; Sengupta, Dipan

    2016-05-01

    We study kinematic distributions that may help characterise the recently observed excess in diphoton events at 750 GeV at the LHC Run 2. Several scenarios are considered, including spin-0 and spin-2 750 GeV resonances that decay directly into photon pairs as well as heavier parent resonances that undergo three-body or cascade decays. We find that combinations of the distributions of the diphoton system and the leading photon can distinguish the topology and mass spectra of the different scenarios, while patterns of QCD radiation can help differentiate the production mechanisms. Moreover, missing energy is a powerful discriminator for the heavy parent scenarios if they involve (effectively) invisible particles. While our study concentrates on the current excess at 750 GeV, the analysis is general and can also be useful for characterising other potential diphoton signals in the future.

  20. Characterising the 750 GeV diphoton excess

    CERN Document Server

    Bernon, Jérémy; Kraml, Sabine; Mawatari, Kentarou; Sengupta, Dipan

    2016-01-01

    We study kinematic distributions that may help characterise the recently observed excess in diphoton events at 750 GeV at the LHC Run 2. Several scenarios are considered, including spin-0 and spin-2 750 GeV resonances that decay directly into photon pairs as well as heavier parent resonances that undergo three-body or cascade decays. We find that combinations of the distributions of the diphoton system and the leading photon can distinguish the topology and mass spectra of the different scenarios, while patterns of QCD radiation can help differentiate the production mechanisms. Moreover, missing energy is a powerful discriminator for the heavy parent scenarios if they involve (effectively) invisible particles. While our study concentrates on the current excess at 750 GeV, the analysis is general and can also be useful for characterising other potential diphoton signals in the future.

  1. Ge laser-generated plasma for ion implantation

    Science.gov (United States)

    Giuffrida, L.; Torrisi, L.; Czarnecka, A.; Wołowski, J.; Quarta, Ge; Calcagnile, L.; Lorusso, A.; Nassisi, V.

    Laser-generated plasma obtained by Ge ablation in vacuum was investigated with the aim to implant energetic Ge ions in light substrates (C, Si, SiO2). Different intensities of laser sources were employed for these experiments: Nd:Yag of Catania-LNS; Nd:Yag of Warsaw-IPPL; excimer laser of Lecce-INFN; iodine laser of Prague-PALS. Different experimental setups were used to generate multiple ion stream emissions, multiple ion energetic distributions, high implantation doses, thin film deposition and post-acceleration effects. `On line' measurements of ion energy were obtained with ion collectors and ion energy analyzer in time-of-flight configuration. `Off line' measurement of Ge implants were obtained with 2.25 MeV helium beam in Rutherford backscattering spectrometry. Results indicated that ion implants show typical deep profiles only for substrates placed along the normal to the target surface at which the ion energy is maximum.

  2. Sub-5 nm, globally aligned graphene nanoribbons on Ge(001)

    Energy Technology Data Exchange (ETDEWEB)

    Kiraly, Brian [Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Building 440, Argonne, Illinois 60439, USA; Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, USA; Mannix, Andrew J. [Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Building 440, Argonne, Illinois 60439, USA; Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, USA; Jacobberger, Robert M. [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; Fisher, Brandon L. [Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Building 440, Argonne, Illinois 60439, USA; Arnold, Michael S. [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; Hersam, Mark C. [Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, USA; Department of Chemistry, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, USA; Guisinger, Nathan P. [Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Building 440, Argonne, Illinois 60439, USA

    2016-05-23

    Graphene nanoribbons (GNRs) hold great promise for future electronics because of their edge and width dependent electronic bandgaps and exceptional transport properties. While significant progress toward such devices has been made, the field has been limited by difficulties achieving narrow widths, global alignment, and atomically pristine GNR edges on technologically relevant substrates. A recent advance has challenged these limits by using Ge(001) substrates to direct the bottom-up growth of GNRs with nearly pristine armchair edges and widths near ~10 nm via atmospheric pressure chemical vapor deposition. In this work, we extend the growth of GNRs on Ge(001) to ultra-high vacuum conditions and realize GNRs narrower than 5 nm. Armchair graphene nanoribbons directed along the Ge <110> surface directions are achieved with excellent width control and relatively large bandgaps. The bandgap magnitude and electronic uniformity make these new materials excellent candidates for future developments in nanoelectronics.

  3. Electrical properties of a-GeSe100-

    Indian Academy of Sciences (India)

    Abdolali Zolanvari; Navdeep Goyal; S K Tripathi

    2004-09-01

    In general, the conductivity in chalcogenide glasses at higher tempratures is dominated by band conduction (DC conduction). But, at lower tempratures, hoping conduction dominates over band conduction. A study at lower temprature can, eventually, provide useful information about the conduction mechanism and the defect states in the material. Therefore, the study of electrical properties of GeSe100- in the lower temperature region (room temperature) is interesting. Temperature and frequency dependence of GeSe100- ( = 15, 20 and 25) have been studied over different range of temperatures and frequencies. Am agreement between experimental and theoretical results suggested that the behaviour of germanium selenium system (GeSe100-) have been successfully explained by correlated barrier hopping (CBH) model.

  4. Low-temperature strain relaxation in SiGe/Si heterostructures implanted with Ge{sup +} ions

    Energy Technology Data Exchange (ETDEWEB)

    Avrutin, V.S.; Izyumskaya, N.F.; Vyatkin, A.F.; Zinenko, V.I.; Agafonov, Yu.A.; Irzhak, D.V.; Roshchupkin, D.V.; Steinman, E.A.; Vdovin, V.I.; Yugova, T.G

    2003-06-15

    Pseudomorphic Si{sub 0.76}Ge{sub 0.24}/Si heterostructures grown by molecular beam epitaxy were implanted with Ge{sup +} ions at 400 deg. C in such a way that an ion-damaged region was located below the SiGe/Si interface. The effect of Ge{sup +}-ion irradiation on strain-relaxation rate and defect structure in the heterostructures was studied by transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscopy (AFM), and low-temperature photoluminescence (PL). It was found that annealing at a temperature as low as 600 deg. C resulted in very high degree of strain relaxation, while density of threading dislocations was low (<10{sup 5} cm{sup -2}). The enhanced strain relaxation was attributed to the fact that complexes of point defects produced by the heavy-ion implantation at the elevated temperature acted as nucleation sites for dislocations. The obtained results allowed us to propose a method for preparation of thin highly relaxed SiGe layer with low threading dislocation density and good surface morphology.

  5. Tight-binding calculation of optical gain in tensile strained [001]-Ge/SiGe quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Pizzi, Giovanni [NEST-CNR-INFM and Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56127 Pisa (Italy); Virgilio, Michele; Grosso, Giuseppe, E-mail: g.pizzi@sns.it [NEST-CNR-INFM and Dipartimento di Fisica ' E. Fermi' , Universita di Pisa, Largo Pontecorvo 3, I-56127 Pisa (Italy)

    2010-02-05

    It is known that under a tensile strain of about 2% of the lattice constant, the energy of the bottom conduction state of bulk Ge at the {Gamma} point falls below the minimum at the L point, leading to a direct gap material. In this paper we investigate how the same condition is realized in tensile strained Ge quantum wells. By means of a tight-binding sp{sup 3}d{sup 5}s* model, we study tensile strained Ge/Si{sub 0.2}Ge{sub 0.8} multiple quantum well (MQW) heterostructures grown on a relaxed SiGeSn alloy buffer along the [001] direction. We focus on values of the strain fields at the crossover between the indirect and direct gap regime of the MQWs, and calculate band edge alignments, electronic band structures, and density of states. We also provide a numerical evaluation of the MQW material gain spectra for TE and TM polarization under realistic carrier injection levels, taking into account the leakages related to the occupation of the electronic states at the L point. The analysis of the different orbital contributions to the near-gap states of the complete structure allows us to give a clear interpretation of the numerical results for the strain-dependent TM/TE gain ratio. Our calculations demonstrate the effectiveness of the structures under consideration for light amplification.

  6. Emission of direct-gap band in germanium with Ge-GeSn layers on one-dimensional structure

    Science.gov (United States)

    Huang, Zhong-Mei; Huang, Wei-Qi; Liu, Shi-Rong; Dong, Tai-Ge; Wang, Gang; Wu, Xue-Ke; Qin, Cao-Jian

    2016-04-01

    In our experiment, it was observed that the emission of direct-gap band in germanium with Ge-GeSn layers on one-dimensional (1D) structure. The results of experiment and calculation demonstrate that the uniaxial tensile strain in the (111) and (110) direction can efficiently transform Ge to a direct bandgap material with the bandgap energy useful for technological application. It is interested that under the tensile strain from Ge-GeSn layers on 1D structure in which the uniaxial strain could be obtained by curved layer (CL) effect, the two bandgaps EΓg and ELg in the (111) direction become nearly equal at 0.83 eV related to the emission of direct-gap band near 1500 nm in the experiments. It is discovered that the red-shift of the peaks from 1500 nm to 1600 nm occurs with change of the uniaxial tensile strain, which proves that the peaks come from the emission of direct-gap band.

  7. Ion Beam Synthesis of Ge Nanowires. rev. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, T.

    2001-01-01

    The formation of Ge nanowires in V-grooves has been studied experimentally as well as theoretically. As substrate oxide covered Si V-grooves were used formed by anisotropic etching of (001)Si wafers and subsequent oxidation of their surface. Implantation of 1 x 10{sup 17} Ge{sup +}cm{sup -2} at 70 keV was carried out into the oxide layer covering the V-grooves. Ion irradiation induces shape changes of the V-grooves, which are captured in a novel continuum model of surface evolution. It describes theoretically the effects of sputtering, redeposition of sputtered atoms, and swelling. Thereby, the time evolution of the target surface is determined by a nonlinear integro-differential equation, which was solved numerically for the V-groove geometry. A very good agreement is achieved for the predicted surface shape and the shape observed in XTEM images. Surprisingly, the model predicts material (Si, O, Ge) transport into the V-groove bottom which also suggests an Ge accumulation there proven by STEM-EDX investigations. In this Ge rich bottom region, subsequent annealing in N{sub 2} atmosphere results in the formation of a nanowire by coalescence of Ge precipitates shown by XTEM images. The process of phase separation during the nanowire growth was studied by means of kinetic 3D lattice Monte-Carlo simulations. These simulations also indicate the disintegration of continuous wires into droplets mediated by thermal fluctuations. Energy considerations have identified a fragmentation threshold and a lower boundary for the droplet radii which were confirmed by the Monte Carlo simulation. The here given results indicate the possibility of achieving nanowires being several nanometers wide by further growth optimizations as well as chains of equally spaced clusters with nearly uniform diameter. (orig.)

  8. Experimental observation of motion of edge dislocations in Ge/Ge x Si1- x /Si(001) ( x = 0.2-0.6) heterostructures

    Science.gov (United States)

    Bolkhovityanov, Yu. B.; Gutakovskii, A. K.; Deryabin, A. S.; Sokolov, L. V.

    2016-11-01

    The Ge/Ge x Si1- x /Si(001) ( x = 0.2-0.6) heterostructures grown by the molecular epitaxy method are analyzed using high-resolution electron microscopy with atomic resolution. The thickness of the Ge x Si1- x buffer layer is 7-35 nm. It is shown that such heterostructures relax in two stages: an ordered network of edge dislocations is formed during their growth (500°C) at the Ge/GeSi interface and then, contrary to the generally accepted opinion concerning their immobility, some of the edge dislocations move through the buffer GeSi layer to the GeSi/Si(001) interface during annealing at higher temperatures and x > 0.3. It is found that plastic relaxation of the GeSi buffer layer occurs due to motion of dislocation complexes of the edge type, consisting of a pair of complementary 60° dislocations with the ends of {111} extra planes located approximately at a distance from 2 to 12 interplanar spacings. It is shown that the penetration of dislocation complexes into the GeSi buffer layer and further to the GeSi/Si interface is intensified with increasing annealing temperature (600-800°C) and the fraction of Ge in the buffer layer.

  9. 70 °C synthesis of high-Sn content (25%) GeSn on insulator by Sn-induced crystallization of amorphous Ge

    Energy Technology Data Exchange (ETDEWEB)

    Toko, K., E-mail: toko@bk.tsukuba.ac.jp; Oya, N.; Suemasu, T. [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Saitoh, N.; Yoshizawa, N. [Electron Microscope Facility, TIA, AIST, 16-1 Onogawa, Tsukuba 305-8569 (Japan)

    2015-02-23

    Polycrystalline GeSn thin films are fabricated on insulating substrates at low temperatures by using Sn-induced crystallization of amorphous Ge (a-Ge). The Sn layer stacked on the a-Ge layer (100-nm thickness each) had two roles: lowering the crystallization temperature of a-Ge and composing GeSn. Slow annealing at an extremely low temperature of 70 °C allowed for a large-grained (350 nm) GeSn layer with a lattice constant of 0.590 nm, corresponding to a Sn composition exceeding 25%. The present investigation paves the way for advanced electronic optical devices integrated on a flexible plastic substrate as well as on a Si platform.

  10. Strained Si/SiGe MOS transistor model

    Directory of Open Access Journals (Sweden)

    Tatjana Pešić-Brđanin

    2009-06-01

    Full Text Available In this paper we describe a new model of surfacechannel strained-Si/SiGe MOSFET based on the extension of non-quasi-static (NQS circuit model previously derived for bulk-Si devices. Basic equations of the NQS model have been modified to account for the new physical parameters of strained-Si and relaxed-SiGe layers. From the comparisons with measurements, it is shown that a modified NQS MOS including steady-state self heating can accurately predict DC characteristics of Strained Silicon MOSFETs.

  11. Hidden GeV-scale interactions of quarks.

    Science.gov (United States)

    Dobrescu, Bogdan A; Frugiuele, Claudia

    2014-08-01

    We explore quark interactions mediated by new gauge bosons of masses in the 0.3-50 GeV range. A tight upper limit on the gauge coupling of light Z(') bosons is imposed by the anomaly cancellation conditions in conjunction with collider bounds on new charged fermions. Limits from quarkonium decays are model dependent, while electroweak constraints are mild. We derive the limits for a Z(') boson coupled to baryon number and then construct a Z(') model with relaxed constraints, allowing quark couplings as large as 0.2 for a mass of a few GeV.

  12. Itinerant magnetism in metallic CuFe2Ge2.

    Science.gov (United States)

    Shanavas, K V; Singh, David J

    2015-01-01

    Theoretical calculations are performed to understand the electronic structure and magnetic properties of CuFe2Ge2. The band structure reveals large electron density N(EF) at the Fermi level suggesting a strong itinerant character of magnetism. The Fermi surface is dominated by two dimensional sheet like structures, with potentially strong nesting between them. The magnetic ground state appears to be ferromagnetic along a and antiferromagnetic in other directions. These results show that CuFe2Ge2 is an antiferromagnetic metal, with similarities to the Fe-based superconductors; such as magnetism with substantial itinerant character and coupling between magnetic order and electrons at the Fermi energy.

  13. Multifragmentation with GeV light-ion beams

    CERN Document Server

    Kwiatkowski, K; Wang, G; Lefort, T; Bracken, D S; Cornell, E; Foxford, E R; Ginger, D S; Viola, V E; Yoder, N R; Korteling, R G; Pollacco, E C; Legrain, R; Volant, C; Gimeno-Nogues, F; Laforest, R; Martin, E; Ramakrishnan, E; Rowland, D; Ruangma, A; Winchester, E M; Yennello, S J; Lynch, W G; Tsang, M B; Xi, H; Breuer, H; Morley, K B; Gushue, S; Remsberg, L P; Pienkowski, L; Brzychczyk, J; Botvina, A; Friedman, W A

    1999-01-01

    Multifragmentation studies with GeV light-ion beams indicate that for the most violent collisions, complex fragments are emitted during expansion of the hot source, followed by near simultaneous breakup of the system near rho/rho sub o approx ((1)/(3)). The results are compared with hybrid INC/EES and INC/SMM models. Preliminary data for the 8 GeV/c pi sup - and p-bar reactions on sup 1 sup 9 sup 7 Au show enhanced deposition energy for the antiproton beam.

  14. Wise Bareheaded Ge You Appears Slow-Witted

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    <正>Feng Xiaogang recently has disputes with Cui Yongyuan due to his film Cell Phone. Each has his reason against the opposite. But nobody knows what result will come out. Maybe it is another trick Feng has made.As one of the key persons involving the event, Ge You, who has played a bit role for dozens of years, is an overwhelming person. It was until the film Mischievous Master that Ge aroused the attention of the film circle.His mother and younger sister has written a new book to tell his story.

  15. Magnetoelastic behaviour of Gd sub 5 Ge sub 4

    CERN Document Server

    Magen, C; Algarabel, P A; Marquina, C; Ibarra, M R

    2003-01-01

    A complete investigation of the complex magnetic behaviour of Gd sub 5 Ge sub 4 by means of linear thermal expansion and magnetostriction measurements (5-300 K, 0-120 kOe) has been carried out. Our results support the suggested existence in this system of a coupled crystallographic-magnetic transition from a Gd sub 5 Ge sub 4 -type Pnma (antiferromagnetic) to a Gd sub 5 Si sub 4 -type Pnma (ferromagnetic) state. Strong magnetoelastic effects are observed at the field-induced first-order magnetic-martensitic transformation. A revised magnetic and crystallographic H- T phase diagram is proposed.

  16. Substrate Effects in Wideband SiGe HBT Mixer Circuits

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Vidkjær, Jens; Krozer, Viktor

    2005-01-01

    In this paper, the influence from substrate effects on the performance of wideband SiGe HBT mixer circuits is investigated. Equivalent circuit models including substrate networks are extracted from on-wafer test structures and compared with electromagnetic simulations. Electromagnetic simulations...... are also applied to predict short distance substrate coupling effects. Simulation results using extracted equivalent circuit models and substrate coupling networks are compared with experimental results obtained on a wideband mixer circuit implemented in a 0.35 μm, 60 GHz ft SiGe HBT BiCMOS process....

  17. Barrierer for at øge markedsorienteret aktivitet

    DEFF Research Database (Denmark)

    Bisp, Søren

    2000-01-01

    Undersøgelsen, der referes i denne artikel, har til formål at bidrage med ny viden om forøgelse af markedsorienteret aktivitet. Dette gøres ved at undersøge, hvilke faktorer der hæmmer tiltag til at øge markedsorienteret aktivitet og specielt, hvordan sådanne faktorer er forbundet og interagerer....... tidshorisont, at der i virksomheden er ledere med bestemte hæmmende personlighedstræk, at man ikke har professionel baggrund i marketing, samt at beslutninger træffes på baggrund af intuition og erfaring....

  18. A 130 GeV Gamma Ray Signal from Supersymmetry

    CERN Document Server

    Shakya, Bibhushan

    2012-01-01

    The viability of neutralino dark matter as an explanation of the 130 GeV gamma ray signal from the Galactic Center recently observed by the Fermi Large Area Telescope is examined. It is found that the signal can be compatible with a sharp feature from internal bremsstrahlung from a mostly bino dark matter particle of mass around 145 GeV, augmented by a contribution from annihilation into gamma+Z via a small wino admixture. This scenario circumvents the problematic overproduction of lower energy continuum photons that plague line interpretations of this signal. Sleptons approximately degenerate in mass with the neutralino are required to enhance the internal bremsstrahlung feature.

  19. Lattice position and thermal stability of diluted As in Ge

    CERN Document Server

    Decoster, S; Cottenier, S; Correia, JG; Mendonça, T; Amorim, LM; Pereira, LMC; Vantomme, A

    2012-01-01

    We present a lattice location study of the n-type dopant arsenic after ion implantation into germanium. By means of electron emission channeling experiments, we have observed that the implanted As atoms substitute the Ge host atoms. However, in contrast to several implanted metal impurities in Ge, no significant fraction of As is found on interstitial sites. The substitutional As impurities are found to be thermally stable up to 600°C. After 700°C annealing a strong reduction of emission channeling effects was observed, in full accordance with the expected diffusion-induced broadening of the As profile.

  20. Extended point defects in crystalline materials: Ge and Si.

    Science.gov (United States)

    Cowern, N E B; Simdyankin, S; Ahn, C; Bennett, N S; Goss, J P; Hartmann, J-M; Pakfar, A; Hamm, S; Valentin, J; Napolitani, E; De Salvador, D; Bruno, E; Mirabella, S

    2013-04-12

    B diffusion measurements are used to probe the basic nature of self-interstitial point defects in Ge. We find two distinct self-interstitial forms--a simple one with low entropy and a complex one with entropy ∼30  k at the migration saddle point. The latter dominates diffusion at high temperature. We propose that its structure is similar to that of an amorphous pocket--we name it a morph. Computational modeling suggests that morphs exist in both self-interstitial and vacancylike forms, and are crucial for diffusion and defect dynamics in Ge, Si, and probably many other crystalline solids.

  1. Advanced far infrared detector and double donor studies in Ge

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, C.S.

    1994-12-01

    This has application to astronomy and astrophysics. Selenium in Ge has been studied with a doping technique which limits complex formation. Only one ionization level has been found to correspond to selenium, which presumably occupies a substitutional site. This level is extremely unstable and its concentration decreases after annealing at 400C. Future work is planned to anneal the fast neutron damage before much selenium has formed in the {sup 74/76}Ge samples. It is expected that the observed selenium level can be better characterized and the missing selenium level is more likely to be discovered if other defects are removed before {sup 77}Se formation.

  2. Structural and Compositional Properties of Strain-Symmetrized SiGe/Si Heterostructures

    Science.gov (United States)

    Ross, I. M.; Gass, M.; Walther, T.; Bleloch, A.; Cullis, A. G.; Lever, L.; Ikonic, Z.; Califano, M.; Kelsall, R. W.; Zhang, J.; Paul, D. J.

    In this study, we have utilised conventional and aberration corrected (scanning) transmission electron microscopy to examine the Ge concentration across a series of technologically significant SiGe/Si prototype heterostructures. Electron energy loss line profiles show that the Ge concentration within the SiGe quantum wells approaches the nominal values. However, the Ge concentration profile shows that the interfaces are not abrupt and that the narrow 0.8nm barrier layer does not reach the nominal pure Si composition. Speculation as to the presence of Ge interdiffusion, surface segregation or interface roughness is discussed.

  3. Nature of defects and gap states in GeTe model phase change materials

    Science.gov (United States)

    Huang, B.; Robertson, J.

    2012-03-01

    The electrical storage mechanism in GeSbTe phase change materials is discussed in terms of their gap states using GeTe as a model system. The lowest energy defect in crystalline rhombohedral GeTe phase is the Ge vacancy, because it reconstructs along the resonant bonding directions. The lowest energy in amorphous GeTe is the divalent Te atom, which creates overlapping band-tail states that pin Fermi level EF near midgap. In contrast, the lowest cost defect in disordered phase in GeSbTe superlattices is the Te interstitial whose negative correlation energy pins EF near midgap.

  4. Properties of slow traps of ALD Al{sub 2}O{sub 3}/GeO{sub x}/Ge nMOSFETs with plasma post oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Ke, M., E-mail: kiramn@mosfet.t.u-tokyo.ac.jp; Yu, X.; Chang, C.; Takenaka, M.; Takagi, S. [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan and JST-CREST, K' s Gobancho 6F, 7 Gobancho, Chiyoda-ku, Tokyo 102-0076 (Japan)

    2016-07-18

    The realization of Ge gate stacks with a small amount of slow trap density as well as thin equivalent oxide thickness and low interface state density (D{sub it}) is a crucial issue for Ge CMOS. In this study, we examine the properties of slow traps, particularly the location of slow traps, of Al{sub 2}O{sub 3}/GeO{sub x}/n-Ge and HfO{sub 2}/Al{sub 2}O{sub 3}/GeO{sub x}/n-Ge MOS interfaces with changing the process and structural parameters, formed by atomic layer deposition (ALD) of Al{sub 2}O{sub 3} and HfO{sub 2}/Al{sub 2}O{sub 3} combined with plasma post oxidation. It is found that the slow traps can locate in the GeO{sub x} interfacial layer, not in the ALD Al{sub 2}O{sub 3} layer. Furthermore, we study the time dependence of channel currents in the Ge n-MOSFETs with 5-nm-thick Al{sub 2}O{sub 3}/GeO{sub x}/Ge gate stacks, with changing the thickness of GeO{sub x}, in order to further clarify the position of slow traps. The time dependence of the current drift and the effective time constant of slow traps do not change among the MOSFETs with the different thickness GeO{sub x}, demonstrating that the slow traps mainly exist near the interfaces between Ge and GeO{sub x}.

  5. Giant magnetocaloric effect in isostructural MnNiGe-CoNiGe system by establishing a Curie-temperature window

    KAUST Repository

    Liu, E. K.

    2013-03-28

    An effective scheme of isostructural alloying was applied to establish a Curie-temperature window in isostructural MnNiGe-CoNiGe system. With the simultaneous accomplishment of decreasing structural-transition temperature and converting antiferromagnetic martensite to ferromagnetic state, a 200 K Curie-temperature window was established between Curie temperatures of austenite and martensite phases. In the window, a first-order magnetostructural transition between paramagnetic austenite and ferromagnetic martensite occurs with a sharp jump in magnetization, showing a magnetic entropy change as large as −40 J kg−1 K−1 in a 50 kOe field change. This giant magnetocaloric effect enables Mn1− x Co x NiGe to become a potential magnetic refrigerant.

  6. Optical and structural investigations of self-assembled Ge/Si bi-layer containing Ge QDs

    Energy Technology Data Exchange (ETDEWEB)

    Samavati, Alireza, E-mail: alireza.samavati@yahoo.com [Ibn Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Othaman, Z., E-mail: zulothaman@gmail.com [Ibn Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Ghoshal, S.K.; Dousti, M.R. [Advanced Optical Material Research Group, Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia)

    2014-10-15

    We report the influence of Si spacer thickness variation (10–40 nm) on structural and optical properties of Ge quantum dots (QDs) in Ge/Si(1 0 0) bi-layer grown by radio frequency magnetron sputtering. AFM images reveal the spacer dependent width, height, root mean square roughness and number density of QDs vary in the range of ∼12–25 nm, ∼2–6 nm, ∼1.95–1.05 nm and ∼0.55×10{sup 11}–2.1×10{sup 11} cm{sup −2}, respectively. XRD patterns exhibit the presence of poly-oriented structures of Ge with preferred growth along (1 1 1) direction accompanied by a reduction in strain from 4.9% to 1.2% (estimated from Williamson–Hall plot) due to bi-layering. The room temperature luminescence displays strong blue–violet peak associated with a blue shift as much as 0.05 eV upon increasing the thickness of Si spacer. This shift is attributed to the quantum size effect, the material intermixing and the strain mediation. Raman spectra for both mono and bi-layer samples show intense Ge–Ge optical phonon mode that is shifted towards higher frequency. Furthermore, the first order features of Raman spectra affirm the occurrence of interfacial intermixing and phase formation during deposition. The excellent features of the results suggest that our systematic method may constitute a basis for the tunable growth of Ge QDs suitable in nanophotonics. - Highlights: • High quality bilayered hetero-structure Ge/Si using economic and easy rf magnetron sputtering fabrication method. • The role of phonon-confinement and strain relaxation mechanisms. • Influence of bilayering on evolutionary growth dynamics. • Band gap shift of visible PL upon bilayering.

  7. Thermal oxidation of Ge-implanted Si: Role of defects

    Science.gov (United States)

    Dedyulin, S. N.; Goncharova, L. V.

    2012-02-01

    Thermal oxidation of Ge-implanted Si (SiGe) was carried out in dry O at 1073, 1173, and 1273 K for various times. Rutherford backscattering spectrometry in random and channeling geometry was used to characterize the SiO thickness and composition of the Si (dry oxidation) [3,4,8,9,13-17] or by bubbling N/O through HO (wet oxidation) [5-7,9-12,18]. In these studies SiGe thin films were obtained by different growth techniques such as chemical vapor deposition (CVD) [4-6,19,12], molecular beam epitaxy (MBE) [7,8,14,19,21-23], physical evaporation [3,18] as well as Ge ion implantation in Si [9-11,13,15-17]. Despite the great differences in the preparation of SiGe samples and oxidation procedures, the main features of SiGe thermal oxidation may be summarized by the following: Pure SiO was formed during oxidation: Ge atoms that were rejected from the growing silicon oxide piled up at the interface. This was observed in all cases, unless the temperature was low enough (⩽973 K)[24], or the oxidation pressure was high [6,19], or the Ge concentration, x, in the alloy satisfied x⩾0.5[7,8], or the oxidation time was very short [22,23]. All these conditions prevent Ge diffusion away from the reacting interface. The oxidation rate of SiGe in a wet atmosphere was enhanced in comparison to pure Si [4,5,9-12,18,25], while there was no enhancement in the dry O[9,16,22,25] (unless the sample was first pre-enriched with Ge to form approximately one monolayer of Ge at the interface [9]). Oxidation rate enhancement occurs during an initial linear regime of oxide growth [10]. SiGe oxidation rate enhancement has been explained by: (i) the weaker Si-Ge bond [11], (ii) Ge catalytic role for oxidation reaction [12], and (iii) changes in defect generation at the reacting interface [12]. It was shown for Ge ion implanted samples that the Deal and Grove model (DG model) for Si oxidation can still be applied with the linear B/ A constant modified to take into account enhanced oxidation

  8. Theoretical prediction for several important equilibrium Ge isotope fractionation factors and geological implications

    Science.gov (United States)

    Li, Xuefang; Zhao, Hui; Tang, Mao; Liu, Yun

    2009-09-01

    This study estimates equilibrium fractionation factors in the Ge isotope system, including the dominant aqueous Ge(OH) 4 and GeO(OH) 3- species in seawater, Ge-bearing organic complexes (e.g. Ge-catechol, Ge-oxalic acid and Ge-citric acid), and Ge in quartz- (or opal-), albite-, K-feldspar-, olivine- and sphalerite-like structures. Estimations are based on Urey model (or Bigeleisen-Mayer equation) and high level quantum chemistry calculations. All calculations are made at B3LYP/6-311 + G(d,p) theory level. Solvation effects are treated by explicit solvent model ("water-droplet" method), and mineral structures are simulated using cluster models, in which the clusters are cut from the X-ray structures of those minerals. In addition, a number of different conformers are used for aqueous complexes in order to reduce the possible errors coming from the differences of configurations in solution. The "salt effect" on GeO(OH) 3-(aq) species is also carefully evaluated. We estimate the accuracy of these fractionation calculations at about ± 0.3‰. Excitedly, very large isotope fractionations are found between many Ge isotope systems. The Ge-containing sulfides (e.g. sphalerite) can extremely enrich light Ge isotopes (more than 10‰) compared with 4-coordinated Ge-O compounds (e.g. Ge(OH) 4(aq) or quartz). The fractionations between Ge(OH) 4(aq) and 6-coordinated Ge-bearing organic complexes can be also up to 4‰ at 25 °C. These results give a good explanation for the experimental observations of Rouxel et al. (2006). It also suggests a great potential for broad application of Ge isotope method in various geological systems.

  9. First-principles calculations on the origin of ferromagnetism in transition-metal doped Ge

    Science.gov (United States)

    Shinya, Hikari; Fukushima, Tetsuya; Masago, Akira; Sato, Kazunori; Katayama-Yoshida, Hiroshi

    2017-09-01

    Many researchers have shown an interest in Ge-based dilute magnetic semiconductors (DMSs) due to potential advantages for semiconductor spintronics applications. There has been great discussion about mechanisms of experimentally observed ferromagnetism in (Ge,Fe) and (Ge,Mn). We investigate the electronic structures, structural stabilities, magnetic exchange coupling constants, and Curie temperature of Ge-based DMSs, and clarify origins of the ferromagnetism, on the basis of density functional theory calculations. In both the (Ge,Fe) and (Ge,Mn) cases, the inhomogeneous distribution of the magnetic impurities plays an important role to determine the magnetic states; however, physical mechanisms of the ferromagnetism in these two materials are completely different. By the spinodal nanodecomposition, the Fe impurities in Ge gather together with keeping the diamond structure, so that the number of the first-nearest-neighbor Fe pairs with strong ferromagnetic interaction increases. Therefore, the Curie temperature drastically increases with the progress of the annealing. Our cluster expansion method clearly reveals that the other ordered compounds with different crystal structures such as Ge3Mn5 and Ge8Mn11 are easily generated in the (Ge,Mn) system. The estimated Curie temperature of Ge3Mn5 is in agreement with the observed Curie temperature in experiments. It should be considered that the precipitation of the ferromagnetic Ge3Mn5 clusters is an origin of high Curie temperature in (Ge,Mn).

  10. Measurement of muon-pair production at 50 GeV < √s < 86 GeV at LEP

    Science.gov (United States)

    Acciarri, M.; Adam, A.; Adriani, O.; Aguilar-Benitez, M.; Ahlen, S.; Alpat, B.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alverson, G.; Alviggi, M. G.; Ambrosi, G.; Anderhub, H.; Andreev, V. P.; Angelescu, T.; Antreasyan, D.; Arefiev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Baksay, L.; Ball, R. C.; Banerjee, S.; Banicz, K.; Barillère, R.; Barone, L.; Bartalini, P.; Baschirotto, A.; Basile, M.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B. L.; Biasini, M.; Biland, A.; Bilei, G. M.; Blaising, J. J.; Blyth, S. C.; Bobbink, G. J.; Bock, R.; Böhm, A.; Borgia, B.; Boucham, A.; Bourilkov, D.; Bourquin, M.; Boutigny, D.; Brambilla, E.; Branson, J. G.; Brigljevic, V.; Brock, I. C.; Buijs, A.; Bujak, A.; Burger, J. D.; Burger, W. J.; Busenitz, J.; Buytenhuijs, A.; Cai, X. D.; Campanelli, M.; Capell, M.; Cara Romeo, G.; Caria, M.; Carlino, G.; Cartacci, A. M.; Casaus, J.; Castellini, G.; Castello, R.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Cesaroni, F.; Chamizo, M.; Chan, A.; Chang, Y. H.; Chaturvedi, U. K.; Chemarin, M.; Chen, A.; Chen, C.; Chen, G.; Chen, G. M.; Chen, H. F.; Chen, H. S.; Chen, M.; Chiefari, G.; Chien, C. Y.; Choi, M. T.; Cifarelli, L.; Cindolo, F.; Civinini, C.; Clare, I.; Clare, R.; Cohn, H. O.; Coignet, G.; Colijn, A. P.; Colino, N.; Commichau, V.; Costantini, S.; Cotorobai, F.; de la Cruz, B.; Dai, T. S.; D'Alessandro, R.; de Asmundis, R.; De Boeck, H.; Degré, A.; Deiters, K.; Denes, P.; DeNotaristefani, F.; DiBitonto, D.; Diemoz, M.; van Dierendonck, D.; Di Lodovico, F.; Dionisi, C.; Dittmar, M.; Dominguez, A.; Doria, A.; Dorne, I.; Dova, M. T.; Drago, E.; Duchesneau, D.; Duinker, P.; Duran, I.; Dutta, S.; Easo, S.; Efremenko, Yu.; El Mamouni, H.; Engler, A.; Eppling, F. J.; Erné, F. C.; Ernenwein, J. P.; Extermann, P.; Fabre, M.; Faccini, R.; Falciano, S.; Favara, A.; Fay, J.; Felcini, M.; Ferguson, T.; Fernandez, D.; Ferroni, F.; Fesefeldt, H.; Fiandrini, E.; Field, J. H.; Filthaut, F.; Fisher, P. H.; Forconi, G.; Fredj, L.; Freudenreich, K.; Galaktionov, Yu.; Ganguli, S. N.; Gau, S. S.; Gentile, S.; Gerald, J.; Gheordanescu, N.; Giagu, S.; Goldfarb, S.; Goldstein, J.; Gong, Z. F.; Gougas, A.; Gratta, G.; Gruenewald, M. W.; Gupta, V. K.; Gurtu, A.; Gutay, L. J.; Hangarter, K.; Hartmann, B.; Hasan, A.; He, J. T.; Hebbeker, T.; Hervé, A.; van Hoek, W. C.; Hofer, H.; Hoorani, H.; Hou, S. R.; Hu, G.; Ilyas, M. M.; Innocente, V.; Janssen, H.; Jin, B. N.; Jones, L. W.; de Jong, P.; Josa-Mutuberria, I.; Kasser, A.; Khan, R. A.; Kamyshkov, Yu.; Kapinos, P.; Kapustinsky, J. S.; Karyotakis, Y.; Kaur, M.; Kienzle-Focacci, M. N.; Kim, D.; Kim, J. K.; Kim, S. C.; Kim, Y. G.; Kinnison, W. W.; Kirkby, A.; Kirkby, D.; Kirkby, J.; Kittel, W.; Klimentov, A.; König, A. C.; Köngeter, A.; Korolko, I.; Koutsenko, V.; Koulbardis, A.; Kraemer, R. W.; Kramer, T.; Krenz, W.; Kuijten, H.; Kunin, A.; Ladron de Guevara, P.; Landi, G.; Lapoint, C.; Lassila-Perini, K.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Lee, J. S.; Lee, K. Y.; Leggett, C.; Le Goff, J. M.; Leiste, R.; Lenti, M.; Leonardi, E.; Levtchenko, P.; Li, C.; Lieb, E.; Lin, W. T.; Linde, F. L.; Lindemann, B.; Lista, L.; Liu, Z. A.; Lohmann, W.; Longo, E.; Lu, W.; Lu, Y. S.; Lübelsmeyer, K.; Luci, C.; Luckey, D.; Ludovici, L.; Luminari, L.; Lustermann, W.; Ma, W. G.; Macchiolo, A.; Maity, M.; Majumder, G.; Malgeri, L.; Malinin, A.; Maña, C.; Mangla, S.; Marchesini, P.; Marin, A.; Martin, J. P.; Marzano, F.; Massaro, G. G. G.; Mazumdar, K.; McNally, D.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W. J.; von der Mey, M.; Mi, Y.; Mihul, A.; van Mil, A. J. W.; Mirabelli, G.; Mnich, J.; Möller, M.; Monteleoni, B.; Moore, R.; Morganti, S.; Mount, R.; Müller, S.; Muheim, F.; Nagy, E.; Nahn, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nippe, A.; Nowak, H.; Organtini, G.; Ostonen, R.; Pandoulas, D.; Paoletti, S.; Paolucci, P.; Park, H. K.; Pascale, G.; Passaleva, G.; Patricelli, S.; Paul, T.; Pauluzzi, M.; Paus, C.; Pauss, F.; Peach, D.; Pei, Y. J.; Pensotti, S.; Perret-Gallix, D.; Petrak, S.; Pevsner, A.; Piccolo, D.; Pieri, M.; Pinto, J. C.; Piroué, P. A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Postema, H.; Produit, N.; Raghavan, R.; Rahal-Callot, G.; Rancoita, P. G.; Rattaggi, M.; Raven, G.; Razis, P.; Read, K.; Redaelli, M.; Ren, D.; Rescigno, M.; Reucroft, S.; Ricker, A.; Riemann, S.; Riemers, B. C.; Riles, K.; Rind, O.; Ro, S.; Robohm, A.; Rodin, J.; Rodriguez, F. J.; Roe, B. P.; Röhner, S.; Romero, L.; Rosier-Lees, S.; Rosselet, Ph.; van Rossum, W.; Roth, S.; Rubio, J. A.; Rykaczewski, H.; Salicio, J.; Sanchez, E.; Santocchia, A.; Sarakinos, M. E.; Sarkar, S.; Sassowsky, M.; Sauvage, G.; Schäfer, C.; Schegelsky, V.; Schmidt-Kaerst, S.; Schmitz, D.; Schmitz, P.; Schneegans, M.; Schoeneich, B.; Scholz, N.; Schopper, H.; Schotanus, D. J.; Schulte, R.; Schultze, K.; Schwenke, J.; Schwering, G.; Sciacca, C.; Sciarrino, D.; Sens, J. C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shukla, J.; Shumilov, E.; Siedenburg, T.; Son, D.; Sopczak, A.; Soulimov, V.; Smith, B.; Spillantini, P.; Steuer, M.; Stickland, D. P.; Sticozzi, F.; Stone, H.; Stoyanov, B.; Straessner, A.; Strauch, K.; Sudhakar, K.; Sultanov, G.; Sun, L. Z.; Susinno, G. F.; Suter, H.; Swain, J. D.; Tang, X. W.; Tauscher, L.; Taylor, L.; Ting, Samuel C. C.; Ting, S. M.; Toker, O.; Tonisch, F.; Tonutti, M.; Tonwar, S. C.; Tóth, J.; Tsaregorodtsev, A.; Tully, C.; Tuchscherer, H.; Tung, K. L.; Ulbricht, J.; Uwer, U.; Valente, E.; Van de Walle, R. T.; Vetlitsky, I.; Viertel, G.; Vivargent, M.; Völkert, R.; Vogel, H.; Vogt, H.; Vorobiev, I.; Vorobyov, A. A.; Vorobyov, An. A.; Vorvolakos, A.; Wadhwa, M.; Wallraff, W.; Wang, J. C.; Wang, X. L.; Wang, Y. F.; Wang, Z. M.; Weber, A.; Wittgenstein, F.; Wu, S. X.; Wynhoff, S.; Xu, J.; Xu, Z. Z.; Yang, B. Z.; Yang, C. G.; Yao, X. Y.; Ye, J. B.; Yeh, S. C.; You, J. M.; Zaccardelli, C.; Zalite, An.; Zemp, P.; Zeng, J. Y.; Zeng, Y.; Zhang, Z.; Zhang, Z. P.; Zhou, B.; Zhou, G. J.; Zhou, Y.; Zhu, G. Y.; Zhu, R. Y.; Zichichi, A.; L3 Collaboration

    1996-02-01

    Using the data recorded with the L3 detector at LEP, we study the process e +e - → μ+μ-( γ) for events with hard initial-state photon radiation. The effective centre-of-mass energies of the muons range from 50 GeV to 86 GeV. The data sample corresponds to an integrated luminosity of 103.5 pb -1 and yields 293 muon-pair events with a hard photon along the beam direction. The events are used to determine the cross sections and the forward-backward charge asymmetries at centre-of-mass energies below the Z resonance.

  11. Search for Spontaneous R-parity violation at $\\sqrt{s}$ = 183 GeV and 189 GeV

    CERN Document Server

    Abreu, P.; Adye, T.; Adzic, P.; Albrecht, Z.; Alderweireld, T.; Alekseev, G.D.; Alemany, R.; Allmendinger, T.; Allport, P.P.; Almehed, S.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Anassontzis, E.G.; Andersson, P.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.D.; Arnoud, Y.; Esman, B.; Augustin, J.E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barao, F.; Barbiellini, G.; Barbier, R.; Bardin, D.Y.; Barker, G.J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.H.; Begalli, M.; Behrmann, A.; Belokopytov, Yu.; Belous, K.; Benekos, N.C.; Benvenuti, A.C.; Berat, C.; Berggren, M.; Berntzon, L.; Bertrand, D.; Besancon, M.; Besson, N.; Bilenky, Mikhail S.; Bloch, D.; Blom, H.M.; Bol, L.; Bonesini, M.; Boonekamp, M.; Booth, P.S.L.; Borisov, G.; Bosio, C.; Botner, O.; Boudinov, E.; Bouquet, B.; Bowcock, T.J.V.; Boyko, I.; Bozovic, I.; Bozzo, M.; Bracko, M.; Branchini, P.; Brenner, R.A.; Brodet, E.; Bruckman, P.; Brunet, J.M.; Bugge, L.; Buschmann, P.; Caccia, M.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Carroll, L.; Caso, C.; Castillo Gimenez, M.V.; Cattai, A.; Cavallo, F.R.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chelkov, G.A.; Chierici, R.; Chliapnikov, P.; Chochula, P.; Chorowicz, V.; Chudoba, J.; Cieslik, K.; Collins, P.; Contri, R.; Cortina, E.; Cosme, G.; Cossutti, F.; Costa, M.; Crawley, H.B.; Crennell, D.; Croix, J.; Cuevas Maestro, J.; Czellar, S.; D'Hondt, J.; Dalmau, J.; Davenport, M.; Da Silva, W.; Della Ricca, G.; Delpierre, P.; Demaria, N.; De Angelis, A.; De Boer, W.; De Clercq, C.; De Lotto, B.; De Min, A.; De Paula, L.; Dijkstra, H.; Di Ciaccio, L.; Doroba, K.; Dracos, M.; Drees, J.; Dris, M.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Engel, J.P.; Espirito Santo, M.C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferrer-Ribas, E.; Ferro, F.; Firestone, A.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fontanelli, F.; Franek, B.; Frodesen, A.G.; Fruhwirth, R.; Fulda-Quenzer, F.; Fuster, J.; Gamba, D.; Gamblin, S.; Gandelman, M.; Garcia, C.; Gaspar, C.; Gaspar, M.; Gasparini, U.; Gavillet, Ph.; Gazis, Evangelos; Gele, D.; Geralis, T.; Ghodbane, N.; Gil Botella, Ines; Glege, F.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Gonzalez Caballero, I.; Gopal, G.; Gorn, L.; Gouz, Yu.; Gracco, V.; Grahl, J.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hahn, F.; Hahn, S.; Haider, S.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Hansen, J.; Harris, F.J.; Haug, S.; Hauler, F.; Hedberg, V.; Heising, S.; Hernandez, J.J.; Herquet, P.; Herr, H.; Hertz, O.; Higon, E.; Holmgren, S.O.; Holt, P.J.; Hoorelbeke, S.; Houlden, M.; Hrubec, J.; Hughes, G.J.; Hultqvist, K.; Jackson, John Neil; Jacobsson, R.; Jalocha, P.; Jarlskog, Ch.; Jarlskog, G.; Jarry, P.; Jean-Marie, B.; Jeans, D.; Johansson, Erik Karl; Jonsson, P.; Joram, C.; Juillot, P.; Jungermann, L.; Kapusta, Frederic; Karafasoulis, K.; Katsanevas, S.; Katsoufis, E.C.; Keranen, R.; Kernel, G.; Kersevan, B.P.; Khokhlov, Yu.A.; Khomenko, B.A.; Khovanski, N.N.; Kiiskinen, A.; King, B.; Kinvig, A.; Kjaer, N.J.; Klapp, O.; Kluit, P.; Kokkinias, P.; Kostioukhine, V.; Kourkoumelis, C.; Kouznetsov, O.; Krammer, M.; Kriznic, E.; Krumstein, Z.; Kubinec, P.; Kucharczyk, M.; Kurowska, J.; Lamsa, J.W.; Laugier, J.P.; Leder, G.; Ledroit, Fabienne; Leinonen, L.; Leisos, A.; Leitner, R.; Lenzen, G.; Lepeltier, V.; Lesiak, T.; Lethuillier, M.; Libby, J.; Liebig, W.; Liko, D.; Lipniacka, A.; Lippi, I.; Loken, J.G.; Lopes, J.H.; Lopez, J.M.; Lopez-Fernandez, R.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Mahon, J.R.; Maio, A.; Malek, A.; Maltezos, S.; Malychev, V.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Marti i Garcia, S.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Matthiae, G.; Mazzucato, F.; Mazzucato, M.; McCubbin, M.; McKay, R.; McNulty, R.; Merle, E.; Meroni, C.; Meyer, W.T.; Miagkov, A.; Migliore, E.; Mirabito, L.; Mitaroff, W.A.; Mjoernmark, U.; Moa, T.; Moch, M.; Monig, Klaus; Monge, M.R.; Montenegro, J.; Moraes, D.; Morettini, P.; Morton, G.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.M.; Murray, W.J.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.L.; Nawrocki, K.; Negri, P.; Nemecek, S.; Neufeld, N.; Nicolaidou, R.; Niezurawski, P.; Nikolenko, M.; Nomokonov, V.; Nygren, A.; Obraztsov, V.; Olshevski, A.G.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Pain, R.; Paiva, R.; Palacios, J.; Palka, H.; Papadopoulou, Th.D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Pernicka, M.; Perrotta, A.; Petridou, C.; Petrolini, A.; Phillips, H.T.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M.E.; Polok, G.; Poropat, P.; Pozdniakov, V.; Privitera, P.; Pukhaeva, N.; Pullia, A.; Radojicic, D.; Ragazzi, S.; Rahmani, H.; Read, Alexander L.; Rebecchi, P.; Redaelli, Nicola Giuseppe; Regler, M.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.B.; Resvanis, L.K.; Richard, F.; Ridky, J.; Rinaudo, G.; Ripp-Baudot, Isabelle; Romero, A.; Ronchese, P.; Rosenberg, E.I.; Rosinsky, P.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ruiz, A.; Saarikko, H.; Sacquin, Y.; Sadovsky, A.; Sajot, G.; Salmi, L.; Salt, J.; Sampsonidis, D.; Sannino, M.; Savoy-Navarro, A.; Schwanda, C.; Schwemling, Ph.; Schwering, B.; Schwickerath, U.; Scuri, Fabrizio; Sedykh, Y.; Segar, A.M.; Sekulin, R.; Sette, G.; Shellard, R.C.; Siebel, M.; Simard, L.; Simonetto, F.; Sisakian, A.N.; Smadja, G.; Smirnova, O.; Smith, G.R.; Sokolov, A.; Solovianov, O.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Spiriti, E.; Squarcia, S.; Stanescu, C.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Strub, R.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Tabarelli, T.; Taffard, A.; Tegenfeldt, F.; Terranova, F.; Timmermans, Jan; Tinti, N.; Tkatchev, L.G.; Tobin, M.; Todorova, S.; Tome, B.; Tonazzo, A.; Tortora, L.; Tortosa, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M.L.; Tyapkin, I.A.; Tyapkin, P.; Tzamarias, S.; Ullaland, O.; Uvarov, V.; Valenti, G.; Vallazza, E.; Van Dam, Piet; Van den Boeck, W.; Van Eldik, J.; Van Lysebetten, A.; van Remortel, N.; Van Vulpen, I.; Vegni, G.; Ventura, L.; Venus, W.; Verbeure, F.; Verdier, P.; Verlato, M.; Vertogradov, L.S.; Verzi, V.; Vilanova, D.; Vitale, L.; Vlasov, E.; Vodopianov, A.S.; Voulgaris, G.; Vrba, V.; Wahlen, H.; Washbrook, A.J.; Weiser, C.; Wicke, D.; Wickens, J.H.; Wilkinson, G.R.; Winter, M.; Witek, M.; Wolf, G.; Yi, J.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zevgolatakos, E.; Zimine, N.I.; Zintchenko, A.; Zoller, Ph.; Zumerle, G.; Zupan, M.

    2001-01-01

    Searches for spontaneous $R$-parity violating signals at $\\sqrt{s}=183$\\,GeV and \\mbox{$\\sqrt{s}=189$\\,GeV} have been performed using 1997 and 1998 DELPHI data, under the assumption of $R$-parity breaking in the third lepton family. The expected topology for the decay of a pair of charginos into two acoplanar taus plus missing energy was investigated and no evidence for a signal was found. The results were used to derive a limit on the chargino mass and to constrain the allowed domains of the MSSM parameter sp.

  12. Effect of deformation on the valence shell occupancies of 74Ge, 76Ge, 76Se and 78Se

    Science.gov (United States)

    Elsharkawy, H. M.; Saleh Yousef, M.

    2017-03-01

    The set of BCS equations have been solved using both realistic and schematic separable forces to calculate the occupation probability amplitudes for protons and neutrons in the valence shells of 74Ge, 76Ge, 76Se and 78Se deformed nuclei. A comparison between the calculated occupation probabilities with the experimental measured values is introduced. A big difference is found between the occupation probabilities of protons with the experimental values, while for neutrons the agreement with the experimental values at high deformations is satisfactory.

  13. QCD studies in $e^{+}e^{-}$ annihilation from 30 GeV to 189 GeV

    CERN Document Server

    Acciarri, M; Adriani, O; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Ambrosi, G; Anderhub, H; Andreev, V P; Angelescu, T; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, L; Balandras, A; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Barone, L; Bartalini, P; Basile, M; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Bhattacharya, S; Biasini, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brigljevic, V; Brochu, F; Buffini, A; Buijs, A; Burger, J D; Burger, W J; Cai, X D; Campanelli, M; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Castellini, G; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada-Canales, M; Cesaroni, F; Chamizo-Llatas, M; Chang, Y H; Chaturvedi, U K; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Civinini, C; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; Cotorobai, F; de la Cruz, B; Csilling, Akos; Cucciarelli, S; Dai, T S; van Dalen, J A; D'Alessandro, R; De Asmundis, R; Déglon, P L; Degré, A; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Van Dierendonck, D N; Di Lodovico, F; Dionisi, C; Dittmar, Michael; Dominguez, A; Doria, A; Dova, M T; Duchesneau, D; Dufournaud, D; Duinker, P; Durán, I; El-Mamouni, H; Engler, A; Eppling, F J; Erné, F C; Extermann, Pierre; Fabre, M; Faccini, R; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Ferroni, F; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gau, S S; Gentile, S; Gheordanescu, N; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hasan, A; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hidas, P; Hirschfelder, J; Hofer, H; Holzner, G; Hoorani, H; Hou, S R; Hu, Y; Iashvili, I; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Khan, R A; Kaur, M; Kienzle-Focacci, M N; Kim, D; Kim, J K; Kirkby, Jasper; Kiss, D; Kittel, E W; Klimentov, A; König, A C; Kopp, A; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lassila-Perini, K M; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Lee, H J; Le Goff, J M; Leiste, R; Leonardi, E; Levchenko, P M; Li Chuan; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luckey, D; Lugnier, L; Luminari, L; Lustermann, W; Ma Wen Gan; Maity, M; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Marchesini, P A; Marian, G; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Von der Mey, M; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Molnár, P; Moulik, T; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Organtini, G; Oulianov, A; Palomares, C; Pandoulas, D; Paoletti, S; Paolucci, P; Paramatti, R; Park, H K; Park, I H; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pieri, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Postema, H; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Raspereza, A V; Raven, G; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Robohm, A; Rodin, J; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Rubio, Juan Antonio; Ruggiero, G; Ruschmeier, D; Rykaczewski, H; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Sarakinos, M E; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Sciarrino, D; Seganti, A; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Smith, B; Spillantini, P; Steuer, M; Stickland, D P; Stone, A; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Suter, H; Swain, J D; Szillási, Z; Sztaricskai, T; Tang, X W; Tauscher, Ludwig; Taylor, L; Tellili, B; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Uchida, Y; Ulbricht, J; Valente, E; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Vorvolakos, A; Wadhwa, M; Wallraff, W; Wang, M; Wang, X L; Wang, Z M; Weber, A; Weber, M; Wienemann, P; Wilkens, H; Wu, S X; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Ye, J B; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhu, G Y; Zhu, R Y; Zichichi, A; Zilizi, G; Zöller, M

    2000-01-01

    We present results obtained from a study of the structure of hadronic events recorded by the L3 detector at various centre-of-mass energies.The distributions of event shape variables and the energy dependence of their mean values are measured from 30 GeV to 189 GeV and compared with various QCD models. The energy dependence of the moments of event shape variables is used to test a power law ansatz for the non-perturbativecomponent. We obtain a universal value of the non-perturbative parameter$\\alpha_{0}$ = 0.537 $\\pm$ 0.073. From a comparison with resummed$\\cal{O}

  14. Effective mass measurement: the influence of hole band nonparabolicity in SiGe/Ge quantum wells

    Science.gov (United States)

    Rössner, Benjamin; von Känel, Hans; Chrastina, Daniel; Isella, Giovanni; Batlogg, Bertram

    2007-01-01

    We show that the common practice of identifying effective masses derived from Shubnikov-de Haas (SdH) and cyclotron resonance measurements with zero-field effective density of states (DOS) masses must be scrutinized when nonparabolicity effects come into play. To this end, the temperature dependence of theoretical SdH oscillations expected for strained-Ge quantum wells is explicitly simulated from calculations of the Landau level structure, giving rise to theoretical masses in exact analogy to a SdH measurement. The calculations are performed within a 6 × 6 envelope function approximation (EFA). The same method is used to calculate the zero-field DOS mass. Our analysis shows that the pronounced nonparabolicity of the heavy hole band leads to a nonlinear magnetic field dependence of Landau level energies invalidating the assumption of equal cyclotron and DOS masses. In particular, we show that at high carrier density the DOS mass is significantly underestimated in a SdH measurement.

  15. 750 GeV diphoton resonance and electric dipole moments

    Science.gov (United States)

    Choi, Kiwoon; Im, Sang Hui; Kim, Hyungjin; Mo, Doh Young

    2016-09-01

    We examine the implication of the recently observed 750 GeV diphoton excess for the electric dipole moments of the neutron and electron. If the excess is due to a spin zero resonance which couples to photons and gluons through the loops of massive vector-like fermions, the resulting neutron electric dipole moment can be comparable to the present experimental bound if the CP-violating angle α in the underlying new physics is of O (10-1). An electron EDM comparable to the present bound can be achieved through a mixing between the 750 GeV resonance and the Standard Model Higgs boson, if the mixing angle itself for an approximately pseudoscalar resonance, or the mixing angle times the CP-violating angle α for an approximately scalar resonance, is of O (10-3). For the case that the 750 GeV resonance corresponds to a composite pseudo-Nambu-Goldstone boson formed by a QCD-like hypercolor dynamics confining at ΛHC, the resulting neutron EDM can be estimated with α ∼(750 GeV /ΛHC) 2θHC, where θHC is the hypercolor vacuum angle.

  16. Promising interpretation of diphoton resonance at 750 GeV

    Science.gov (United States)

    Bi, Xiao-Jun; Ding, Ran; Fan, Yizhou; Huang, Li; Li, Chuang; Li, Tianjun; Raza, Shabbar; Wang, Xiao-Chuan; Zhu, Bin

    2016-07-01

    Recently, an excess of events in diphoton channel with invariant mass of about 750 GeV has been reported by the ATLAS and CMS Collaborations. Considering it as a tantalizing hint for new physics beyond the Standard Model (SM), we propose a simple extension of the SM with an additional doublet Higgs H' and a singlet s . We consider the neutral component H0' of H' as the 750 GeV resonance and assume that s is lighter than 2.6 GeV. In particular, H0' can be produced at tree level via q q ¯ production and decay into a pair of s at tree level. Then s can decay into a pair of collimated photons, which cannot be distinguished at the LHC. We show that the diphoton production cross section can be from 3 to 13 fb, the decay width of H0' can be from 30 to 60 GeV, and all the current experimental constraints including dijet constraint can be satisfied.

  17. 750 GeV diphoton resonance and electric dipole moments

    Directory of Open Access Journals (Sweden)

    Kiwoon Choi

    2016-09-01

    Full Text Available We examine the implication of the recently observed 750 GeV diphoton excess for the electric dipole moments of the neutron and electron. If the excess is due to a spin zero resonance which couples to photons and gluons through the loops of massive vector-like fermions, the resulting neutron electric dipole moment can be comparable to the present experimental bound if the CP-violating angle α in the underlying new physics is of O(10−1. An electron EDM comparable to the present bound can be achieved through a mixing between the 750 GeV resonance and the Standard Model Higgs boson, if the mixing angle itself for an approximately pseudoscalar resonance, or the mixing angle times the CP-violating angle α for an approximately scalar resonance, is of O(10−3. For the case that the 750 GeV resonance corresponds to a composite pseudo-Nambu–Goldstone boson formed by a QCD-like hypercolor dynamics confining at ΛHC, the resulting neutron EDM can be estimated with α∼(750 GeV/ΛHC2θHC, where θHC is the hypercolor vacuum angle.

  18. GeV C. W. electron microtron design report

    Energy Technology Data Exchange (ETDEWEB)

    1982-05-01

    Rising interest in the nuclear physics community in a GeV C.W. electron accelerator reflects the growing importance of high-resolution short-range nuclear physics to future advances in the field. In this report major current problems are reviewed and the details of prospective measurements which could be made with a GeV C.W. electron facility are discussed, together with their impact on an understanding of nuclear forces and the structure of nuclear matter. The microtron accelerator has been chosen as the technology to generate the electron beams required for the research discussed because of the advantages of superior beam quality, low capital and operating cost and capability of furnishing beams of several energies and intensities simultaneously. A complete technical description of the conceptual design for a 2 GeV double-sided C.W. electron microtron is presented. The accelerator can furnish three beams with independently controlled energy and intensity. The maximum current per beam is 100 ..mu..amps. Although the precise objective for maximum beam energy is still a subject of debate, the design developed in this study provides the base technology for microtron accelerators at higher energies (2 to 6 GeV) using multi-sided geometries.

  19. Thermoelectric Properties of Czochralski GeSi Crystal

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In order to discuss the application possibility of SiGe crystal in thermoelectric materials, we investigated the thermoelectric properties of several silicon-germanium alloys with different content, orientation and electric conductive type. As discussed in the experiment result, the absolute value of Seebeck coefficient fluctuates from 300 to 600 μV/K in the whole temperature range. In the present paper, the relationship of Seebeck coefficient against content, orientation and electric conductive type is summarized in detail. The Seebeck coefficient of the sample with 〈111〉orientation is smaller than that in 〈100〉 at the same temperature. Absolute value of P-type is larger than that of N-type except pure Ge. But as the temperature increases, the absolute value of pure Ge decreases many times as quickly as that of other specimens. In addition, the specimens of bulk GeSi alloy crystals for experiment were grown by the Czochralski method through varying the pulling rate during the growing process.

  20. Tilflyttere til nybyggeri i Køge Kommune

    DEFF Research Database (Denmark)

    Haagerup, Christian Deichmann; Ærø, Thorkild

    2009-01-01

    I rapporten er udviklet metoder og redskaber, som den kommunale planlægning kan benytte i håndteringen af demografi ske og kommunaløkonomiske udfordringer i fremtiden. Rapporten belyser, ved hjælp af spørgeskemaundersøgelse og fokusgruppeinterviews, tilflytterne til nybyggeri i Køge Kommune samt ...

  1. The JLAB 12 GeV Energy Upgrade of CEBAF

    Energy Technology Data Exchange (ETDEWEB)

    Harwood, Leigh H. [JLAB

    2013-12-01

    This presentation should describe the progress of the 12GeV Upgrade of CEBAF at Jefferson Lab. The status of the upgrade should be presented as well as details on the construction, procurement, installation and commissioning of the magnet and SRF components of the upgrade.

  2. CMS event at 900 GeV - 5 May 2015

    CERN Multimedia

    CMS, Collaboration

    2015-01-01

    This proton collision di-jet event was detected at the CMS detector. The red bars represent the energy deposited in the electromagnetic calorimeter and the blue represent the energy in the hadronic calorimeter. The total hadronic and electromagnetic energy is approximately 30 GeV in each jet. The back-to-back jet cones can be clearly seen emanating from the vertex.

  3. Demand Response Performance of GE Hybrid Heat Pump Water Heater

    Energy Technology Data Exchange (ETDEWEB)

    Widder, Sarah H.; Parker, Graham B.; Petersen, Joseph M.; Baechler, Michael C.

    2013-07-01

    This report describes a project to evaluate and document the DR performance of HPWH as compared to ERWH for two primary types of DR events: peak curtailments and balancing reserves. The experiments were conducted with GE second-generation “Brillion”-enabled GeoSpring hybrid water heaters in the PNNL Lab Homes, with one GE GeoSpring water heater operating in “Standard” electric resistance mode to represent the baseline and one GE GeoSpring water heater operating in “Heat Pump” mode to provide the comparison to heat pump-only demand response. It is expected that “Hybrid” DR performance, which would engage both the heat pump and electric elements, could be interpolated from these two experimental extremes. Signals were sent simultaneously to the two water heaters in the side-by-side PNNL Lab Homes under highly controlled, simulated occupancy conditions. This report presents the results of the evaluation, which documents the demand-response capability of the GE GeoSpring HPWH for peak load reduction and regulation services. The sections describe the experimental protocol and test apparatus used to collect data, present the baselining procedure, discuss the results of the simulated DR events for the HPWH and ERWH, and synthesize key conclusions based on the collected data.

  4. Energy relaxation in optically excited Si and Ge nanocrystals

    NARCIS (Netherlands)

    S. Saeed

    2014-01-01

    The scientific objective of the research presented in this thesis is to explore energy relaxation processes of optically excited Si and Ge nanocrystals. The identification and deeper understanding of unique energy relaxation paths in these materials will open a new window of opportunity for these ma

  5. Anomalous activation of shallow B+ implants in Ge

    DEFF Research Database (Denmark)

    Yates, B.R.; Darby, B.L.; Rudawski, N.G.;

    2011-01-01

    The electrical activation of B+ implantation at 2 keV to doses of 5.0×1013-5.0×1015 cm-2 in crystalline and pre-amorphized Ge following annealing at 400 °C for 1.0 h was studied using micro Hall effect measurements. Preamorphization improved activation for all samples with the samples implanted...... to a dose of 5.0×1015 cm-2 displaying an estimated maximum active B concentration of 4.0×1020 cm-3 as compared to 2.0×1020 cm-3 for the crystalline sample. However, incomplete activation was observed for all samples across the investigated dose range. For the sample implanted to a dose of 5.0×1013 cm -2......, activation values were 7% and 30%, for c-Ge and PA-Ge, respectively. The results suggest the presence of an anomalous clustering phenomenon of shallow B+ implants in Ge. © 2011 Elsevier B.V. All rights reserved....

  6. Tunable thermal hysteresis in MnFe(P,Ge) compounds

    NARCIS (Netherlands)

    Trung, N.T.; Ou, Z.Q.; Gortenmulder, T.J.; Tegus, O.; Buschow, K.H.J.; Brück, E.

    2009-01-01

    Structural, magnetic, and magnetocaloric properties of the MnFe(P,Ge) compounds were systematically studied on both bulk alloys and melt-spun ribbons. The experimental results show that the critical behavior of the phase transition can be controlled by changing either the compositions or the anneali

  7. Impurity and defect interactions during laser thermal annealing in Ge

    Energy Technology Data Exchange (ETDEWEB)

    Milazzo, R., E-mail: ruggero.milazzo@unipd.it; De Salvador, D.; Carnera, A.; Napolitani, E. [CNR-IMM MATIS and Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); Impellizzeri, G.; Privitera, V. [CNR-IMM MATIS and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, 95123 Catania (Italy); Piccinotti, D. [CNR-IMM MATIS and Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); IM2NP, CNRS-Universités d' Aix-Marseille et de Toulon, Case 142, 13397 Marseille Cedex 20 (France); La Magna, A. [CNR-IMM, Z.I. VIII Strada 5, 95121 Catania (Italy); Fortunato, G. [CNR-IMM, Via del Fosso del Cavaliere 100, 00133 Roma (Italy); Portavoce, A.; Mangelinck, D. [IM2NP, CNRS-Universités d' Aix-Marseille et de Toulon, Case 142, 13397 Marseille Cedex 20 (France)

    2016-01-28

    The microscopic mechanisms involving dopants, contaminants, and defects in Ge during pulsed melting laser thermal annealing (LTA) are investigated in detail. Samples both un-implanted and implanted with As or B are processed by LTA as well as characterized in terms of chemical (1D and 3D), electrical, and strain profiling. The clustering of As is directly measured by 3D chemical profiling and correlated with its partial electrical activation along with a reduction of the lattice strain induced by As atoms. A semi-quantitative microscopic model involving the interaction with mobile As-vacancy (AsV) complexes is proposed to describe the clustering mechanism. Boron is shown to follow different clustering behavior that changes with depth and marked by completely different strain levels. Oxygen penetrates from the surface into all the samples as a result of LTA and, only in un-implanted Ge, it occupies an interstitial position inducing also positive strain in the lattice. On the contrary, data suggest that the presence of As or B forces O to assume different configurations with negligible strain, through O-V or O-B interactions for the two dopant species, respectively. These data suggest that LTA does not inject a significant amount of vacancies in Ge, at variance with Si, unless As atoms or possibly other n-type dopants are present. These results have to be carefully considered for modeling the LTA process in Ge and its implementation in technology.

  8. Mechanical properties of bismuth implanted amorphous Ge film

    Energy Technology Data Exchange (ETDEWEB)

    Juhasz, A.; Szommer, P.; Lendvai, J.; Vertesy, Z.; Peto, G. E-mail: peto@mfa.kfki.hu

    1999-01-02

    Mechanical properties of Bi ion implanted a-Ge film were studied by dynamic microhardness tests and compared to those of unimplanted a-Ge film. 400 nm thick films were evaporated in units of 30 nm thick layers and bombarded with Bi ions at 60 keV energy and 2 {mu}A/cm{sup 2} current. Cyclic load-unload indentation tests and indentation creep tests were performed to determine the hardness and ductility of the ion implanted and unimplanted specimens, respectively. The brittleness of the materials was characterised by scanning electron microscopic observation of crack formation around the Vickers indentations. The dynamic hardness was much larger, the ductility lower, the crack formation was significantly larger in the case of the unimplanted than in the ion bombarded specimens. The observed differences in the mechanical properties indicate structural differences between the two types of a-Ge are in agreement with the earlier reported formation of a new amorphous phase of Ge induced by ion implantation (G. Peto, J. Kanski, U. Sodervall, Phys. Lett. 124 (1987) 510)

  9. Mechanical properties of bismuth implanted amorphous Ge film

    Science.gov (United States)

    Juhász, A.; Szommer, P.; Lendvai, J.; Vértesy, Z.; Pető, G.

    1999-01-01

    Mechanical properties of Bi ion implanted a-Ge film were studied by dynamic microhardness tests and compared to those of unimplanted a-Ge film. 400 nm thick films were evaporated in units of 30 nm thick layers and bombarded with Bi ions at 60 keV energy and 2 μA/cm 2 current. Cyclic load-unload indentation tests and indentation creep tests were performed to determine the hardness and ductility of the ion implanted and unimplanted specimens, respectively. The brittleness of the materials was characterised by scanning electron microscopic observation of crack formation around the Vickers indentations. The dynamic hardness was much larger, the ductility lower, the crack formation was significantly larger in the case of the unimplanted than in the ion bombarded specimens. The observed differences in the mechanical properties indicate structural differences between the two types of a-Ge are in agreement with the earlier reported formation of a new amorphous phase of Ge induced by ion implantation (G. Pető, J. Kanski, U. Sodervall, Phys. Lett. 124 (1987) 510 [6]).

  10. 7-GeV Advanced Photon Source Conceptual Design Report

    Energy Technology Data Exchange (ETDEWEB)

    1987-04-01

    During the past decade, synchrotron radiation emitted by circulating electron beams has come into wide use as a powerful, versatile source of x-rays for probing the structure of matter and for studying various physical processes. Several synchrotron radiation facilities with different designs and characteristics are now in regular operation throughout the world, with recent additions in this country being the 0.8-GeV and 2.5-GeV rings of NSLS at Brookhaven National Laboratory. However, none of the operating facilities has been designed to use a low-emittance, high-energy stored beam, together with modern undulator devices, to produce a large number of hard x-ray beams of extremely high brilliance. This document is a proposal to the Department of Energy to construct and operate high-energy synchrotron radiation facility at Argonne National Laboratory. We have now chosen to set the design energy of this facility at 7.0 GeV, with the capability to operate at up to 7.5 GeV.

  11. Ge post-acceleration from laser-generated plasma

    Science.gov (United States)

    Giuffrida, L.; Torrisi, L.; Calcagnile, L.; Rosinski, M.

    2010-11-01

    An Nd:YAG laser, 1064 nm wavelength, 9 ns pulse width, 300-900 mJ pulse energy and 10 10 W/cm 2 intensity is employed to ablate a solid Ge target placed in high vacuum. Ions are produced in vacuum and are emitted mainly along the normal to the target surface. The free ion expansion process occurs in a constant-potential chamber placed at 30 kV positive voltage with respect to the ground. The post-acceleration system permits to extract Ge ions with energy proportional to the charge state. Ion Energy Analyzer (IEA) is employed to measure the energy-to-charge ratio of the Ge ions without and with the use of the post-acceleration system. The ion energy distribution can be measured from time-of-flight measurements. Multi-energetic ion implantation has been performed on Silicon substrates. Ge depth profiles, measured through RBS analysis are in good agreement with IEA spectroscopy measurements.

  12. Ge post-acceleration from laser-generated plasma

    Energy Technology Data Exchange (ETDEWEB)

    Giuffrida, L., E-mail: lorenzogiuffrida@lns.infn.i [INFN-LNS di Catania, Via S. Sofia 62, 95123 Catania (Italy) and Dipartimento di Fisica, Universita di Messina, Ctr. Papardo 31, 98166 S. Agata, Messina (Italy); Torrisi, L. [INFN-LNS di Catania, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica, Universita di Messina, Ctr. Papardo 31, 98166 S. Agata, Messina (Italy); Calcagnile, L. [CEDAD, Dip.to di Ing. dell' Innov., Universita di Lecce, Via Monteroni, 73100, Lecce (Italy); Rosinski, M. [Institute of Plasma Physics and Laser Microfusion, 23 Hery Str. 01-497 Warsaw (Poland)

    2010-11-11

    An Nd:YAG laser, 1064 nm wavelength, 9 ns pulse width, 300-900 mJ pulse energy and 10{sup 10} W/cm{sup 2} intensity is employed to ablate a solid Ge target placed in high vacuum. Ions are produced in vacuum and are emitted mainly along the normal to the target surface. The free ion expansion process occurs in a constant-potential chamber placed at 30 kV positive voltage with respect to the ground. The post-acceleration system permits to extract Ge ions with energy proportional to the charge state. Ion Energy Analyzer (IEA) is employed to measure the energy-to-charge ratio of the Ge ions without and with the use of the post-acceleration system. The ion energy distribution can be measured from time-of-flight measurements. Multi-energetic ion implantation has been performed on Silicon substrates. Ge depth profiles, measured through RBS analysis are in good agreement with IEA spectroscopy measurements.

  13. Geïntegreerde bestrijding van cicaden in de glastuinbouw

    NARCIS (Netherlands)

    Pijnakker, J.; Ramakers, P.M.J.; Slooten, van M.A.; Kok, L.W.; Leman, A.; Bulle, A.A.E.

    2008-01-01

    Op verzoek van de werkgroep Strateeg van LTO Groeiservice en met financiering van het Productschap Tuinbouw begon Wageningen UR Glastuinbouw in mei 2005 met een onderzoek aan cicaden in kassen. De voorkomende soorten werden geïnventariseerd, en mogelijkhedenvoor zowel biologsiche als chemische bestr

  14. Magnetic structure at low temperatures in FeGe2

    Science.gov (United States)

    Babu, P. D.; Mishra, P. K.; Dube, V.; Mishra, R.; Sastry, P. U.; Ravikumar, G.

    2014-04-01

    Magnetic phase of FeGe2 intermetallic is studied using low-temperature neutron diffraction and DC magnetization. Zero-magnetic-field neutron scattering data shows the presence of an antiferromagnetic phase in the low temperature range. We find the evidence of the presence of a ferromagnetic order overriding on the predominantly antiferromagnetic phase at low temperatures.

  15. Giant missing row reconstruction of Au on Ge(001)

    NARCIS (Netherlands)

    van Houselt, Arie; Fischer, Marinus; Poelsema, Bene; Zandvliet, Henricus J.W.

    2008-01-01

    We report on a giant missing row reconstruction emerging upon the adsorption and subsequent annealing of (sub)monolayer amounts of Au on Ge(001). The emerging microfacets are of (111) type and reminiscent of those in the well-known (2×1) missing row reconstruction of the clean (110) surfaces of the

  16. Tunable thermal hysteresis in MnFe(P,Ge) compounds

    NARCIS (Netherlands)

    Trung, N.T.; Ou, Z.Q.; Gortenmulder, T.J.; Tegus, O.; Buschow, K.H.J.; Brück, E.

    2009-01-01

    Structural, magnetic, and magnetocaloric properties of the MnFe(P,Ge) compounds were systematically studied on both bulk alloys and melt-spun ribbons. The experimental results show that the critical behavior of the phase transition can be controlled by changing either the compositions or the anneali

  17. USA hiiglane GE Healthcare korraldab meditsiinis revolutsiooni / Andrew Jack

    Index Scriptorium Estoniae

    Jack, Andrew

    2006-01-01

    General Electricu tütarettevõte GE Healthcare võttis üle Briti diagnostika- ja bioteaduse uurimisfirma Amersham, firma strateegia tuum on võimsa skaneerimistehnoloogia ja meditsiinilise diagnostika üksteisele lähendamine. Lisa: Aeg sorteerida andmeid infotehnoloogia abil

  18. 12 GeV detector technology at Jefferson Lab

    Science.gov (United States)

    Leckey, John P.; GlueX Collaboration

    2013-04-01

    The Thomas Jefferson National Accelerator Facility (JLab) is presently in the middle of an upgrade to increase the energy of its CW electron beam from 6 GeV to 12 GeV along with the addition of a fourth experimental hall. Driven both by necessity and availability, novel detectors and electronics modules have been used in the upgrade. One such sensor is the Silicon Photomultiplier (SiPM), specifically a Multi-Pixel Photon Counter (MPPC), which is an array of avalanche photodiode pixels operating in Geiger mode that are used to sense photons. The SiPMs replace conventional photomultiplier tubes and have several distinct advantages including the safe operation in a magnetic field and the lack of need for high voltage. Another key to 12 GeV success is advanced fast electronics. Jlab will use custom 250 MHz and 125 MHz 12-bit analog to digital converters (ADCs) and time to digital converters (TDCs) all of which take advantage of VME Switched Serial (VXS) bus with its GB/s high bandwidth readout capability. These new technologies will be used to readout drift chambers, calorimeters, spectrometers and other particle detectors at Jlab once the 12 GeV upgrade is complete. The largest experiment at Jlab utilizing these components is GlueX - an experiment in the newly constructed Hall D that will study the photoproduction of light mesons in the search for hybrid mesons. The performance of these components and their respective detectors will be presented.

  19. Antilocalization of Coulomb Blockade in a Ge-Si Nanowire

    DEFF Research Database (Denmark)

    Higginbotham, Andrew P.; Kuemmeth, Ferdinand; Larsen, Thorvald Wadum

    2014-01-01

    The distribution of Coulomb blockade peak heights as a function of magnetic field is investigated experimentally in a Ge-Si nanowire quantum dot. Strong spin-orbit coupling in this hole-gas system leads to antilocalization of Coulomb blockade peaks, consistent with theory. In particular, the peak...

  20. Sputtering of Ge(001): transition between dynamic scaling regimes

    DEFF Research Database (Denmark)

    Smilgies, D.-M.; Eng, P.J.; Landemark, E.;

    1997-01-01

    We have studied the dynamic behavior of the Ge(001) surface during sputtering in situ and in real time using synchrotron X-ray diffraction. We find two dynamic regimes as a function of surface temperature and sputter current which are separated by a sharp transition. The boundary between these two...

  1. 12 GeV detector technology at Jefferson Lab

    Energy Technology Data Exchange (ETDEWEB)

    Leckey, John P. [Indiana U.

    2013-04-01

    The Thomas Jefferson National Accelerator Facility (JLab) is presently in the middle of an upgrade to increase the energy of its CW electron beam from 6 GeV to 12 GeV along with the addition of a fourth experimental hall. Driven both by necessity and availability, novel detectors and electronics modules have been used in the upgrade. One such sensor is the Silicon Photomultiplier (SiPM), specifically a Multi-Pixel Photon Counter (MPPC), which is an array of avalanche photodiode pixels operating in Geiger mode that are used to sense photons. The SiPMs replace conventional photomultiplier tubes and have several distinct advantages including the safe operation in a magnetic field and the lack of need for high voltage. Another key to 12 GeV success is advanced fast electronics. Jlab will use custom 250 MHz and 125 MHz 12-bit analog to digital converters (ADCs) and time to digital converters (TDCs) all of which take advantage of VME Switched Serial (VXS) bus with its GB/s high bandwidth readout capability. These new technologies will be used to readout drift chambers, calorimeters, spectrometers and other particle detectors at Jlab once the 12 GeV upgrade is complete. The largest experiment at Jlab utilizing these components is GlueX - an experiment in the newly constructed Hall D that will study the photoproduction of light mesons in the search for hybrid mesons. The performance of these components and their respective detectors will be presented.

  2. 12 GeV detector technology at Jefferson Lab

    Energy Technology Data Exchange (ETDEWEB)

    Leckey, John P. [Indiana University, Bloomington, IN 47405 (United States); Collaboration: GlueX Collaboration

    2013-04-19

    The Thomas Jefferson National Accelerator Facility (JLab) is presently in the middle of an upgrade to increase the energy of its CW electron beam from 6 GeV to 12 GeV along with the addition of a fourth experimental hall. Driven both by necessity and availability, novel detectors and electronics modules have been used in the upgrade. One such sensor is the Silicon Photomultiplier (SiPM), specifically a Multi-Pixel Photon Counter (MPPC), which is an array of avalanche photodiode pixels operating in Geiger mode that are used to sense photons. The SiPMs replace conventional photomultiplier tubes and have several distinct advantages including the safe operation in a magnetic field and the lack of need for high voltage. Another key to 12 GeV success is advanced fast electronics. Jlab will use custom 250 MHz and 125 MHz 12-bit analog to digital converters (ADCs) and time to digital converters (TDCs) all of which take advantage of VME Switched Serial (VXS) bus with its GB/s high bandwidth readout capability. These new technologies will be used to readout drift chambers, calorimeters, spectrometers and other particle detectors at Jlab once the 12 GeV upgrade is complete. The largest experiment at Jlab utilizing these components is GlueX - an experiment in the newly constructed Hall D that will study the photoproduction of light mesons in the search for hybrid mesons. The performance of these components and their respective detectors will be presented.

  3. Electrical and Optical Characterization of Si-Ge-Sn

    Science.gov (United States)

    2012-03-01

    the typical mounting brackets were too large to hold the samples. The FTIR uses a Michelson -type interferometer. The optical path difference is...al., "Tensile-strained, n-type Ge as a Gain Medium for Monolithic Laser Integration on Si," Optical Express 15 (18), 11272 (2007). 32. W. C. Dash

  4. Combined wet and dry cleaning of SiGe(001)

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang Wook; Kaufman-Osborn, Tobin; Kim, Hyonwoong [Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093 (United States); Siddiqui, Shariq; Sahu, Bhagawan [TD Research, GLOBALFOUNDRIES USA, Inc., 257 Fuller Road, Albany, New York 12203 (United States); Yoshida, Naomi; Brandt, Adam [Applied Materials, Inc., Santa Clara, California 95054 (United States); Kummel, Andrew C., E-mail: akummel@ucsd.edu [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093 (United States)

    2015-07-15

    Combined wet and dry cleaning via hydrofluoric acid (HF) and atomic hydrogen on Si{sub 0.6}Ge{sub 0.4}(001) surface was studied at the atomic level using ultrahigh vacuum scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and x-ray photoelectron spectroscopy to understand the chemical transformations of the surface. Aqueous HF removes native oxide, but residual carbon and oxygen are still observed on Si{sub 0.6}Ge{sub 0.4}(001) due to hydrocarbon contamination from post HF exposure to ambient. The oxygen contamination can be eliminated by shielding the sample from ambient via covering the sample in the HF cleaning solution until the sample is introduced to the vacuum chamber or by transferring the sample in an inert environment; however, both processes still leave carbon contaminant. Dry in-situ atomic hydrogen cleaning above 330 °C removes the carbon contamination on the surface consistent with a thermally activated atomic hydrogen reaction with surface hydrocarbon. A postdeposition anneal at 550 °C induces formation of an atomically flat and ordered SiGe surface observed by STM. STS verifies that the wet and dry cleaned surface has an unpinned Fermi level with no states between the conduction and valence band edge comparable to sputter cleaned SiGe surfaces.

  5. Structure and Photoluminescence of Mullite.Ge Nanocomposite

    Institute of Scientific and Technical Information of China (English)

    GAO Le; WANG Hao; WANG Weimin; FU Zhengyi

    2008-01-01

    Al12Si3.75Ge0.25O26 ceramic powder was prepared by sol-gel method using Al(NO3)3,Si(OC2H5)4 and Cl3GeCH2-CH2COOH as precursors.The structural formation of Al12Si3.75Ge0.25O26 ceramic powder was analyzed by XRD.After reduction by flowing H2/Ar mixture gas,strong room temperature photoluminescence (PL) can be observed at 565 nm,613 nm,682 nm,731 nm and 777 nm,respectively.The PL intensity scarcely depends on the reduction temperature and duration,while the sample reduced at 500 ℃ for 3 hours has the highest PL intensity.Before and after reduction at 500 ℃,the volume of unit cell of mullite solid solution decreases to 0.4699 (A)3.Based on the analysis of XPS and Raman spectra,it can be approved that the PL phenomenon at room temperature is caused by the embedded Ge nanoparticles with the average size of about 1.95 nm.

  6. USA hiiglane GE Healthcare korraldab meditsiinis revolutsiooni / Andrew Jack

    Index Scriptorium Estoniae

    Jack, Andrew

    2006-01-01

    General Electricu tütarettevõte GE Healthcare võttis üle Briti diagnostika- ja bioteaduse uurimisfirma Amersham, firma strateegia tuum on võimsa skaneerimistehnoloogia ja meditsiinilise diagnostika üksteisele lähendamine. Lisa: Aeg sorteerida andmeid infotehnoloogia abil

  7. Inclusive hadron production at 10 GeV

    Science.gov (United States)

    Waldi, R.

    1989-12-01

    Recent results of the ARGUS collaboration on inclusive momentum and angular distributions of charged hadrons produced in direct Υ(1S) decays and nonresonant e+e- annihilation at 10 GeV are presented, which allow investigation of quark and gluon fragmentation. The data demonstrate some of the shortcomings of present fragmentation models.

  8. Development of an improved performance SiGe unicouple

    Science.gov (United States)

    Nakahara, Jan F.; Franklin, Brian; DeFillipo, Lawrence E.

    1995-01-01

    This paper describes the fabrication of unicouples with improved SiGe alloys. Based on laboratory measurements of the thermoelectric properties the improved materials provide about a 10% improvement in the figure-of-merit between 573 and 1273 K compared to standard coarse grain unicouple materials. The improved materials are p-type Si0.796Ge0.199B0.005 fabricated at Martin Marietta Astro Space by the Vacuum casting/hot pressing method and n-type Si0.784Ge0.196Ga0.005P0.015 fabricated at Ames Laboratory by the mechanical alloying/hot isostatic pressing method. The standard unicouple bonding process was adjusted to accommodate the lower melting temperature of the SiGe/GaP material. A two-step diffusion bonding process was developed such that the p-type material is bonded to the SiMo hot shoe first at 1594 K followed by the lower melting point n-type material between 1518 and 1520 K. Standard procedures were used to silicon nitride coat the thermoelectric pellets and to attach the cold side CTE transition and heat rejection components to produce unicouples. Two unicouples successfully withstood simulated rivet operations as would be experienced in the fabrication of a Radioisotope Thermoelectric Generator (RTG) converter to verify the integrity of the tungsten cold shoe to thermoelectric material interface. The performance of these unicouples will be further evaluated in an 18-couple test module.

  9. SiGe Building Blocks for Microwave Frequency Synthesizers

    OpenAIRE

    Vaucher, Cicero S.; Apostolidou, M; Farrugia, Andrew; Praamsma, Louis

    2004-01-01

    Implementations of Ku- and Ka-band PLL building blocks in the Philips QUBiC4G SiGe technology are presented: a 10 GHz fully-integrated low-phase-noise differential Colpttis oscillator, a 25 GHz low-power adaptive prescaler, and a 18 GHz truly-modular fully-programmable frequency divider.

  10. Characterization of Ge-nanocrystal films with photoelectron spectroscopy

    CERN Document Server

    Bostedt, C; Willey, T M; Nelson, A J; Franco, N; Möller, T; Terminello, L J

    2003-01-01

    The Ge 3d core-levels of germanium nanocrystal films have been investigated by means of photoelectron spectroscopy. The experiments indicate bulk-like coordinated atoms in the nanocrystals and suggest structured disorder on the nanoparticle surface. The results underline the importance of the surface on the overall electronic structure of this class of nanostructured materials.

  11. The phase diagram of annealed Ge(111)/Ga

    DEFF Research Database (Denmark)

    Molinàs-Mata, P.; Böhringer, M.; Artacho, E.;

    1995-01-01

    A study of the annealed phases of Ge(111)/Ga for coverages above 0.05 ML is presented. The surfaces are investigated by low-energy electron diffraction, scanning tunneling microscopy, and partly by photoemission and surface X-ray diffraction using synchrotron radiation. For Ga coverages beyond 0....

  12. 300 GeV Up-dated design study

    CERN Multimedia

    1967-01-01

    The 'Report on the Design Study of a 300 GeV Proton Synchrotron' (document CERN/ 563) was issued in November 1964. An Addendum (document CERN/702) to this Design Study was issued on 30 May as one of the up-to-date set of documents and relevant costs presented to the June Council Meeting.

  13. 750 GeV diphoton resonance and electric dipole moments

    CERN Document Server

    Choi, Kiwoon; Kim, Hyungjin; Mo, Doh Young

    2016-01-01

    We examine the implication of the recently observed 750 GeV diphoton excess for the electric dipole moments of the neutron and electron. If the excess is due to a spin zero resonance which couples to photons and gluons through the loops of massive vector-like fermions, the resulting neutron electric dipole moment can be comparable to the present experimental bound if the CP-violating angle {\\alpha} in the underlying new physics is of O(10^{-1}). An electron EDM comparable to the present bound can be achieved through a mixing between the 750 GeV resonance and the Standard Model Higgs boson, if the mixing angle itself for an approximately pseudoscalar resonance, or the mixing angle times the CP-violating angle {\\alpha} for an approximately scalar resonance, is of O(10^{-3}). For the case that the 750 GeV resonance corresponds to a composite pseudo-Nambu-Goldstone boson formed by a QCD-like hypercolor dynamics confining at \\Lambda_HC, the resulting neutron EDM can be estimated with \\alpha ~ (750 GeV / \\Lambda_HC...

  14. XML Schema of PaGE-OM: fuge.xsd [

    Lifescience Database Archive (English)

    Full Text Available cters that identifies an abstract or physical resource. FuGE (http://fuge.sourceforge.net/) is a model of the shared compon...://www.omg.org/spec/PAGE-OM/20090722/snp schemaLocation=snp.xsd/> ... type=fuge:Ontology_source/> rce> The source... maxOccurs=1> A URI is short for Uniform Resource Identifier.

  15. Defect and dislocation structures in low-temperature-grown Ge and Ge{sub 1−x}Sn{sub x} epitaxial layers on Si(110) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kidowaki, Shohei [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Asano, Takanori [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Research Fellow of Japan Society for the Promotion of Science, 5-3-1, Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Shimura, Yosuke [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kurosawa, Masashi [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Taoka, Noriyuki [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Nakatsuka, Osamu, E-mail: nakatuka@alice.xtal.nagoya-u.ac.jp [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Zaima, Shigeaki [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2016-01-01

    We have investigated the epitaxial growth and crystalline properties of Ge{sub 1−x}Sn{sub x} layers on a Si(110) substrate. We found that the twin growth in the Ge epitaxial layer deposited on the Si(110) using molecular beam epitaxy at a low temperature of 200 °C can be effectively suppressed by the incorporation of 2.0% Sn. We also examined the strain relaxation of annealed Ge{sub 1−x}Sn{sub x}/Si(110) samples. The degree of strain relaxation is enhanced by the annealing process, and the threading dislocation in the Ge{sub 1−x}Sn{sub x} layers decreases from 10{sup 11} cm{sup −2} to 10{sup 10} cm{sup −2} because of the propagation of misfit dislocations. We also observed misfit dislocations formed at the Ge{sub 1−x}Sn{sub x}/Si interface, which would effectively promote isotropic strain relaxation in the Ge{sub 1−x}Sn{sub x} layers. - Highlights: • Suppression of twin in GeSn growth on Si(110) substrate • Isotropic strain relaxation of Ge and GeSn layers by misfit dislocation network • Achievement of high quality GeSn epitaxial layers on Si(110) by post deposition annealing.

  16. A high performance Ge/Si0.5Ge0.5/Si heterojunction dual sources tunneling transistor with a U-shaped channel

    Science.gov (United States)

    Li, Wei; Liu, Hongxia; Wang, Shulong; Wang, Qianqiong; Chen, Shupeng

    2017-06-01

    In this paper, a new Ge/Si0.5Ge0.5/Si heterojunction dual sources tunneling transistor with a U-shaped channel (Ge_DUTFET) is proposed and investigated by Silvaco-Atlas simulation. The line tunneling perpendicular to channel and point tunneling parallel to channel simultaneously occur on both sides of the gate. The Ge is chosen as the source region material to increase the line tunneling current. The designed heterojunction between the Ge source and Si channel decreases the point tunneling barrier width to enhance the point tunneling current. And this heterojunction can also promote the Ge_DUTFET to occur point tunneling at the small gate voltage, which makes it obtain the smaller turn-on voltage. Furthermore, the Si0.5Ge0.5 buffer layer is also helpful for the enhancement of performance. The simulation results reveal that Ge_DUTFET has the better performance compared with the Si_DUTFET. The on-state current and average subthreshold swing of Ge_DUTFET are 1.11 × 10-5A/μm and 35.1mV/dec respectively. The max cut-off frequency (fT) and gain bandwidth product (GBW) are 26.6 GHz and 16.6 GHz respectively. The fT and GBW of the Ge_DUTFET are respectively increased by ∼27.4% and ∼84.3% compared with the Si_DUTFET.

  17. Evidence of GeO volatilization and its effect on the characteristics of HfO2 grown on a Ge substrate

    Institute of Scientific and Technical Information of China (English)

    Fan Ji-Bin; Liu Hong-Xia; Fei Cheng-Xi; Ma Fei; Fan Xiao-Jiao; Hao Yue

    2013-01-01

    HfO2 films are deposited by atomic layer deposition (ALD) using tetrakis ethylmethylamino hafnium (TEMAH) as the hafnium precursor,while O3 or H2O is used as the oxygen precursor.After annealing at 500 ℃ in nitrogen,the thickness of Ge oxide's interfacial layer decreases,and the presence of GeO is observed at the H2O-based HfO2 interface due to GeO volatilization,while it is not observed for the O3-based HfO2.The difference is attributed to the residue hydroxyl groups or H2O molecules in H2O-based HfO2 hydrolyzing GeO2 and forming GeO,whereas GeO is only formed by the typical reaction mechanism between GeO2 and the Ge substrate for O3-based HfO2 after annealing.The volatilization of GeO deteriorates the characteristics of the high-κ films after annealing,which has effects on the variation of valence band offset and the C-V characteristics of HfO2/Ge after annealing.The results are confirmed by X-ray photoelectron spectroscopy (XPS) and electrical measurements.

  18. Restrictions of Si-based Ge nanodots from porous alumina membranes

    Science.gov (United States)

    Zhan, Wenbo; Huangfu, Yourui; Ding, Guqiao; Ye, Hui

    2013-08-01

    This paper reports growth of ordered Ge nanodots (NDs) with uniform sizes on silicon substrates using porous alumina membranes (PAMs) as templates. The relationships between substrate temperatures (400-600 °C) and site distribution of Ge NDs are studied. Ordered arrangements of Ge NDs are realized at 400 °C and 500 °C, respectively. Due to joint effect of substrate temperature and restrictions from PAM, an uncommon size change trend is found. At 400 °C, triangular pyramid-like and short cylindrical Ge NDs are obtained with different nanopore aspect ratios of PAMs. A geometrical optic method is used to analyze the mechanism of Ge NDs with such shapes. Raman characterization is utilized to study the strain in Ge NDs. As a result, almost pure Ge content and 1.5% tensile strain are revealed, which are attributed respectively to the low substrate temperature and thermal mismatch among Si substrate, Ge ND and PAM.

  19. Study of GeSn based heterostructures: towards optimized group IV MQW LEDs

    National Research Council Canada - National Science Library

    Stange, D; von den Driesch, N; Rainko, D; Schulte-Braucks, C; Wirths, S; Mussler, G; Tiedemann, A T; Stoica, T; Hartmann, J M; Ikonic, Z; Mantl, S; Grützmacher, D; Buca, D

    2016-01-01

    .... An alternative solution using SiGeSn as barrier material is introduced, which provides appropriate band alignment for both electrons and holes resulting in efficient confinement in direct bandgap GeSn wells...

  20. Room Temperature Ferromagnetic, Anisotropic, Germanium Rich FeGe(001 Alloys

    Directory of Open Access Journals (Sweden)

    Cristian M. Teodorescu

    2013-02-01

    Full Text Available Ferromagnetic FexGe1−x with x = 2%–9% are obtained by Fe deposition onto Ge(001 at high temperatures (500 °C. Low energy electron diffraction (LEED investigation evidenced the preservation of the (1 × 1 surface structure of Ge(001 with Fe deposition. X-ray photoelectron spectroscopy (XPS at Ge 3d and Fe 2p core levels evidenced strong Fe diffusion into the Ge substrate and formation of Ge-rich compounds, from FeGe3 to approximately FeGe2, depending on the amount of Fe deposited. Room temperature magneto-optical Kerr effect (MOKE evidenced ferromagnetic ordering at room temperature, with about 0.1 Bohr magnetons per Fe atom, and also a clear uniaxial magnetic anisotropy with the in-plane  easy magnetization axis. This compound is a good candidate for promising applications in the field of semiconductor spintronics.

  1. Ge-intercalated graphene: The origin of the p-type to n-type transition

    KAUST Repository

    Kaloni, Thaneshwor P.

    2012-09-01

    Recently huge interest has been focussed on Ge-intercalated graphene. In order to address the effect of Ge on the electronic structure, we study Ge-intercalated free-standing C 6 and C 8 bilayer graphene, bulk C 6Ge and C 8Ge, as well as Ge-intercalated graphene on a SiC(0001) substrate, by density functional theory. In the presence of SiC(0001), there are three ways to obtain n-type graphene: i) intercalation between C layers; ii) intercalation at the interface to the substrate in combination with Ge deposition on the surface; and iii) cluster intercalation. All other configurations under study result in p-type states irrespective of the Ge coverage. We explain the origin of the different doping states and establish the conditions under which a transition occurs. © Copyright EPLA, 2012.

  2. Development of a production scale purification of Ge-68 from irradiated gallium metal

    Energy Technology Data Exchange (ETDEWEB)

    Fitzsimmons, Jonathan M.; Mausner, Leonard [Brookhaven National Laboratory, Upton, NY (United States)

    2015-05-01

    Germanium-68 (Ge-68) is produced by proton irradiation of a gallium metal target and purified by organic extraction. The Ge-68 can be used in a medical isotope generator to produce Gallium-68 (Ga-68) which can be used to radiolabel PET imaging agents. The emerging use of Ge-68 in the Ga-68 medical isotope generator has caused us to develop a new purification method for Ge-68 that does not use toxic solvents. The purpose of this work was to develop a production scale separation of Ge-68 that utilizes a leaching step to remove a bulk of the gallium metal, followed by purification with Sephadex {sup copyright} G25. Production scale (300 mCi) purification was performed with the new method. The purified Ge-68 contained the highest radioactivity concentration of Ge-68 produced at BNL; the sample meet Department of Energy specifications and the method had an excellent recovery of Ge-68.

  3. 76 FR 14437 - Economic Simplified Boiling Water Reactor Standard Design: GE Hitachi Nuclear Energy; Issuance of...

    Science.gov (United States)

    2011-03-16

    ... From the Federal Register Online via the Government Publishing Office ] NUCLEAR REGULATORY COMMISSION Economic Simplified Boiling Water Reactor Standard Design: GE Hitachi Nuclear Energy; Issuance of... GE Hitachi Nuclear Energy (GEH) for the economic simplified boiling water reactor (ESBWR) standard...

  4. Effects of Ge replacement in GeTe by Ag or Sb on the Seebeck coefficient and carrier concentration modified by local electron imbalance

    Science.gov (United States)

    Levin, E. M.; Howard, A.; Straszheim, W. E.

    2015-03-01

    XRD, SEM, EDS, 125Te NMR, Seebeck coefficient, and electrical resistivity of AgxGe50-xTe50 and SbxGe50-xTe50 alloys have been studied. Replacement of Ge in GeTe by Sb significantly increases the Seebeck coefficient, while replacement by Ag decreases it. These effects can be attributed to a change in carrier concentration observed via 125Te NMR spin-lattice relaxation measurements and NMR signal position, which mostly depends on the Knight shift. Variation in carrier concentration in AgxGe50-xTe50 and SbxGe50-xTe50 can be attributed to different electron configurations of valence electrons of Ag (4d105s1) and Sb (5s25p3) compared to that of Ge (4s24p2) resulting in local electron imbalances and changing the concentration of charge carrier (holes) generated by Ge vacancies. In contrast, our 125Te NMR and Seebeck coefficient data for Ag2Sb2Ge46Te50 are similar to those observed for GeTe. This shows that effects from Ag and Sb compensate each other and indicates the existence of [Ag +Sb] pairs. The effects of Ge replacement in GeTe by Ag, Sb, or [Ag +Sb] on rhombohedral lattice distortion also have been analyzed. Interplay between the Seebeck coefficient and electrical resistivity in these alloys results in variation of power factor; the value of 45 mW/cm K2, the highest among known tellurides, was found for Sb2Ge48Te50.

  5. SiGe layer thickness effect on the structural and optical properties of well-organized SiGe/SiO2 multilayers

    Science.gov (United States)

    Vieira, E. M. F.; Toudert, J.; Rolo, A. G.; Parisini, A.; Leitão, J. P.; Correia, M. R.; Franco, N.; Alves, E.; Chahboun, A.; Martín-Sánchez, J.; Serna, R.; Gomes, M. J. M.

    2017-08-01

    In this work, we report on the production of regular (SiGe/SiO2)20 multilayer structures by conventional RF-magnetron sputtering, at 350 °C. Transmission electron microscopy, scanning transmission electron microscopy, raman spectroscopy, and x-ray reflectometry measurements revealed that annealing at a temperature of 1000 °C leads to the formation of SiGe nanocrystals between SiO2 thin layers with good multilayer stability. Reducing the nominal SiGe layer thickness (t SiGe) from 3.5-2 nm results in a transition from continuous SiGe crystalline layer (t SiGe ˜ 3.5 nm) to layers consisting of isolated nanocrystals (t SiGe ˜ 2 nm). Namely, in the latter case, the presence of SiGe nanocrystals ˜3-8 nm in size, is observed. Spectroscopic ellipsometry was applied to determine the evolution of the onset in the effective optical absorption, as well as the dielectric function, in SiGe multilayers as a function of the SiGe thickness. A clear blue-shift in the optical absorption is observed for t SiGe ˜ 2 nm multilayer, as a consequence of the presence of isolated nanocrystals. Furthermore, the observed near infrared values of n = 2.8 and k = 1.5 are lower than those of bulk SiGe compounds, suggesting the presence of electronic confinement effects in the nanocrystals. The low temperature (70 K) photoluminescence measurements performed on annealed SiGe/SiO2 nanostructures show an emission band located between 0.7-0.9 eV associated with the development of interface states between the formed nanocrystals and surrounding amorphous matrix.

  6. Structure of glassy GeO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Salmon, Philip S [Department of Physics, University of Bath, Bath BA2 7AY (United Kingdom); Barnes, Adrian C [H H Wills Physics Laboratory, Royal Fort, Tyndall Avenue, University of Bristol, BS8 1TL (United Kingdom); Martin, Richard A [Department of Physics, University of Bath, Bath BA2 7AY (United Kingdom); Cuello, Gabriel J [Institut Laue-Langevin, BP 156, F-38042, Grenoble Cedex 9 (France)

    2007-10-17

    The full set of partial structure factors for glassy germania, or GeO{sub 2}, were accurately measured by using the method of isotopic substitution in neutron diffraction in order to elucidate the nature of the pair correlations for this archetypal strong glass former. The results show that the basic tetrahedral Ge(O{sub 1/2}){sub 4} building blocks share corners with a mean inter-tetrahedral Ge-O-circumflex-Ge bond angle of 132(2){sup 0}. The topological and chemical ordering in the resultant network displays two characteristic length scales at distances greater than the nearest neighbour. One of these describes the intermediate range order, and manifests itself by the appearance of a first sharp diffraction peak in the measured diffraction patterns at a scattering vector k{sub FSDP}{approx}1.53 A{sup -1}, while the other describes so-called extended range order, and is associated with the principal peak at k{sub PP} = 2.66(1) A{sup -1}. We find that there is an interplay between the relative importance of the ordering on these length scales for tetrahedral network forming glasses that is dominated by the extended range ordering with increasing glass fragility. The measured partial structure factors for glassy GeO{sub 2} are used to reproduce the total structure factor measured by using high energy x-ray diffraction and the experimental results are also compared to those obtained by using classical and first principles molecular dynamics simulations.

  7. Growth and self-organization of SiGe nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Aqua, J.-N., E-mail: aqua@insp.jussieu.fr [Institut des Nanosciences de Paris, Université Pierre et Marie Curie Paris 6 and CNRS UMR 7588, 4 place Jussieu, 75252 Paris (France); Berbezier, I., E-mail: isabelle.berbezier@im2np.fr [Institut Matériaux Microélectronique Nanoscience de Provence, Aix-Marseille Université, UMR CNRS 6242, 13997 Marseille (France); Favre, L. [Institut Matériaux Microélectronique Nanoscience de Provence, Aix-Marseille Université, UMR CNRS 6242, 13997 Marseille (France); Frisch, T. [Institut Non Linéaire de Nice, Université de Nice Sophia Antipolis, UMR CNRS 6618, 1361 routes des Lucioles, 06560 Valbonne (France); Ronda, A. [Institut Matériaux Microélectronique Nanoscience de Provence, Aix-Marseille Université, UMR CNRS 6242, 13997 Marseille (France)

    2013-01-01

    Many recent advances in microelectronics would not have been possible without the development of strain induced nanodevices and bandgap engineering, in particular concerning the common SiGe system. In this context, a huge amount of literature has been devoted to the growth and self-organization of strained nanostructures. However, even if an overall picture has been drawn out, the confrontation between theories and experiments is still, under various aspects, not fully satisfactory. The objective of this review is to present a state-of-the-art of theoretical concepts and experimental results on the spontaneous formation and self-organization of SiGe quantum dots on silicon substrates. The goal is to give a comprehensive overview of the main experimental results on the growth and long time evolution of these dots together with their morphological, structural and compositional properties. We also aim at describing the basis of the commonly used thermodynamic and kinetic models and their recent refinements. The review covers the thermodynamic theory for different levels of elastic strain, but focuses also on the growth dynamics of SiGe quantum dots in several experimental circumstances. The strain driven kinetically promoted instability, which is the main form of instability encountered in the epitaxy of SiGe nanostructures at low strain, is described. Recent developments on its continuum description based on a non-linear analysis particularly useful for studying self-organization and coarsening are described together with other theoretical frameworks. The kinetic evolution of the elastic relaxation, island morphology and film composition are also extensively addressed. Theoretical issues concerning the formation of ordered island arrays on a pre-patterned substrate, which is governed both by equilibrium ordering and kinetically-controlled ordering, are also reported in connection with the experimental results for the fabrication technology of ordered arrays of SiGe

  8. Higgs Mass and Cross-Section Measurements at a 500 GeV CLIC Machine, Operating at sqrt(s) = 350 GeV and 500 GeV

    CERN Document Server

    Marshall, J

    2012-01-01

    Higgs mass and cross-section measurements have been examined to assess the capability of a 500 GeV CLIC machine, operating at centre-of-mass energies of 350 GeV and 500 GeV. A Higgs mass of 120 GeV and a luminosity of 500 fb−1 were assumed. Model-independent measurements were performed by examining the recoil of the Z in the Higgsstrahlung process, with the Z subsequently decaying to a pair of muons or electrons.

  9. Synthesis and structures of type-I clathrates: Rb6Na2Ge44.89(1), Cs6Na2Zn4Ge42 and Cs6.40(1)Na1.60(1)Ga8Ge38

    Science.gov (United States)

    Zhang, Hui; Mu, Gang; Huang, Fuqiang; Xie, Xiaoming

    2016-10-01

    Type-I clathrates of Rb6Na2Ge44.89(1), Cs6Na2Zn4Ge42 and Cs6.40(1)Na1.60(1)Ga8Ge38 were synthesized via solid-state reaction. Rb6Na2Ge44.89(1), Cs6Na2Zn4Ge42 and Cs6.40(1)Na1.60(1)Ga8Ge38 were found to crystalize in the cubic space group of Pm 3 ̅ n with lattice parameters of a=10.72755(5) Å, a=10.79501(8) Å and a=10.79726(5) Å, respectively. Theoretical calculations indicated semiconducting features for the calculation models of Rb6Na2Ge44, Cs6Na2Zn4Ge42 and Cs6Na2Ga8Ge38 with band gaps of 0.002 eV, 0.297 eV and 0.221 eV, respectively.

  10. Black GE based on crystalline/amorphous core/shell nanoneedle arrays

    Science.gov (United States)

    Javey, Ali; Chueh, Yu-Lun; Fan, Zhiyong

    2014-03-04

    Direct growth of black Ge on low-temperature substrates, including plastics and rubber is reported. The material is based on highly dense, crystalline/amorphous core/shell Ge nanoneedle arrays with ultrasharp tips (.about.4 nm) enabled by the Ni catalyzed vapor-solid-solid growth process. Ge nanoneedle arrays exhibit remarkable optical properties. Specifically, minimal optical reflectance (black Ge can have important practical implications for efficient photovoltaic and photodetector applications on nonconventional substrates.

  11. Optimum strain configurations for carrier injection in near infrared Ge lasers

    Science.gov (United States)

    Aldaghri, O.; Ikonić, Z.; Kelsall, R. W.

    2012-03-01

    The behavior of direct and indirect valleys in Ge, and the bandgap shrinking, under different tensile-strain conditions in bulk Ge and Ge quantum well structures are explored using the deformation potential and k .p methods. The doping density required for filling the indirect valleys up to the Γ-valley is calculated for various strain and growth conditions, as well as the efficiency of electron injection into the Γ-valley, and the optimum cases for Ge laser operation are identified.

  12. Return of the Volcano: PHENIX Azimuthal Correlations 62.4 GeV Au+Au

    CERN Document Server

    McCumber, M; Cumber, Michael Mc; Frantz, Justin

    2005-01-01

    As in previous analyses at sqrt(s_NN) 200 GeV, correlations in azimuthal angles between inclusive charge particles at intermediate transverse momentum (p_T = 1.0-4.0) GeV/c are studied at sqrt(s_NN) 62.4 GeV. The jet correlations reveal similar modification as in 200 GeV. Specifically large modification, including the "volcano" or "cone" structure, persists in the awayside correlation.

  13. Delayed plastic relaxation limit in SiGe islands grown by Ge diffusion from a local source

    Energy Technology Data Exchange (ETDEWEB)

    Vanacore, G. M.; Zani, M.; Tagliaferri, A., E-mail: alberto.tagliaferri@polimi.it [CNISM-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Nicotra, G. [IMM-CNR, Stradale Primosole 50, I-95121 Catania (Italy); Bollani, M. [CNR-IFN, LNESS, Via Anzani 42, I-22100 Como (Italy); Bonera, E.; Montalenti, F.; Picco, A.; Boioli, F. [Dipartimento di Scienza dei Materiali and L-NESS, Università Milano-Bicocca, via Cozzi 53, I-20125 Milano (Italy); Capellini, G. [Department of Sciences at the Università Roma Tre, Via Vasca Navale 79, 00146 Roma (Italy); Isella, G. [CNISM, LNESS, Dipartimento di Fisica, Politecnico di Milano (Polo di Como), Via Anzani 42, I-22100 Como (Italy); Osmond, J. [ICFO–The Institute of Photonic Sciences, Av. Carl Friedrich Gauss, 3, E-08860 Castelldefels (Barcelona) (Spain)

    2015-03-14

    The hetero-epitaxial strain relaxation in nano-scale systems plays a fundamental role in shaping their properties. Here, the elastic and plastic relaxation of self-assembled SiGe islands grown by surface-thermal-diffusion from a local Ge solid source on Si(100) are studied by atomic force and transmission electron microscopies, enabling the simultaneous investigation of the strain relaxation in different dynamical regimes. Islands grown by this technique remain dislocation-free and preserve a structural coherence with the substrate for a base width as large as 350 nm. The results indicate that a delay of the plastic relaxation is promoted by an enhanced Si-Ge intermixing, induced by the surface-thermal-diffusion, which takes place already in the SiGe overlayer before the formation of a critical nucleus. The local entropy of mixing dominates, leading the system toward a thermodynamic equilibrium, where non-dislocated, shallow islands with a low residual stress are energetically stable. These findings elucidate the role of the interface dynamics in modulating the lattice distortion at the nano-scale, and highlight the potential use of our growth strategy to create composition and strain-controlled nano-structures for new-generation devices.

  14. Passivation of multiple-quantum-well Ge0.97Sn0.03/Ge p-i-n photodetectors

    Science.gov (United States)

    Morea, Matthew; Brendel, Corinna E.; Zang, Kai; Suh, Junkyo; Fenrich, Colleen S.; Huang, Yi-Chiau; Chung, Hua; Huo, Yijie; Kamins, Theodore I.; Saraswat, Krishna C.; Harris, James S.

    2017-02-01

    We study the effect of surface passivation on pseudomorphic multiple-quantum-well Ge0.97Sn0.03/Ge p-i-n photodetectors. A combination of ozone oxidation to form GeOx and GeSnOx on the surface of the diodes followed by atomic layer deposition of Al2O3 for protection of these native oxides provides reduced dark current. With a temperature-dependent investigation of dark current, we calculate the activation energy to be 0.26 eV at a bias of -0.1 V and 0.05 eV at -1 V for the sample passivated by this ozone method. Based on these activation energy results, we find that the current is less dominated by bulk tunneling at lower reverse bias values; hence, the effect of surface passivation is more noticeable with nearly an order-of-magnitude improvement in dark current for the ozone-passivated sample compared to control devices without the ozone treatment at a voltage of -0.1 V. Passivation also results in a significant enhancement of the responsivity, particularly for shorter wavelengths, with 26% higher responsivity at 1100 nm and 16% higher performance at 1300 nm.

  15. Sn-enriched Ge/GeSn nanostructures grown by MBE on (001) GaAs and Si wafers

    Energy Technology Data Exchange (ETDEWEB)

    Sadofyev, Yu. G., E-mail: sadofyev@hotmail.com; Martovitsky, V. P.; Klekovkin, A. V. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Saraykin, V. V. [Lukin Research Institute of Physical Problems (Russian Federation); Vasil’evskii, I. S. [National Research Nuclear University MEPhI (Russian Federation)

    2015-12-15

    Elastically stressed metastable GeSn layers with a tin molar fraction as large as 0.185 are grown on (001) Si and GaAs wafers covered with a germanium buffer layer. A set of wafers with a deviation angle in the range 0°–10° is used. It is established that the GeSn crystal undergoes monoclinic deformation with the angle β to 88° in addition to tetragonal deformation. Misorientation of the wafers surface results in increasing efficiency of the incorporation of tin adatoms into the GeSn crystal lattice. Phase separation in the solid solution upon postgrowth annealing of the structures begins long before the termination of plastic relaxation of elastic heteroepitaxial stresses. Tin released as a result of GeSn decomposition predominantly tends to be found on the surface of the sample. Manifestations of the brittle–plastic mechanism of the relaxation of stresses resulting in the occurrence of microcracks in the subsurface region of the structures under investigation are found.

  16. Rapid solidification and dendrite growth of ternary Fe-Sn-Ge and Cu-Pb-Ge monotectic alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The phase separation and dendrite growth characteristics of ternary Fe-43.9%Sn- 10%Ge and Cu-35.5%Pb-5%Ge monotectic alloys were studied systematically by the glass fluxing method under substantial undercooling conditions. The maximum undercoolings obtained in this work are 245 and 257 K, respectively, for these two alloys. All of the solidified samples exhibit serious macrosegregation, indicating that the homogenous alloy melt is separated into two liquid phases prior to rapid solidification. The solidification structures consist of four phases including α-Fe, (Sn), FeSn and FeSn2 in Fe-43.9%Sn-10%Ge ternary alloy, whereas only (Cu) and (Pb) solid solution phases in Cu-35.5%Pb-5%Ge alloy under different undercool- ings. In the process of rapid monotectic solidification, α-Fe and (Cu) phases grow in a dendritic mode, and the transition "dendrite→monotectic cell" happens when alloy undercoolings become sufficiently large. The dendrite growth velocities of α-Fe and (Cu) phases are found to increase with undercooling according to an exponential relation.

  17. Rapid solidification and dendrite growth of ternary Fe-Sn-Ge and Cu-Pb-Ge monotectic alloys

    Institute of Scientific and Technical Information of China (English)

    ZHANG XueHua; RUAN Ying; WANG WeiLi; WEI BingBo

    2007-01-01

    The phase separation and dendrite growth characteristics of ternary Fe-43.9%Sn- 10%Ge and Cu-35.5%Pb-5%Ge monotectic alloys were studied systematically by the glass fluxing method under substantial undercooling conditions. The maximum undercoolings obtained in this work are 245 and 257 K, respectively, for these two alloys. All of the solidified samples exhibit serious macrosegregation, indicating that the homogenous alloy melt is separated into two liquid phases prior to rapid solidification. The solidification structures consist of four phases including α-Fe, (Sn), FeSn and FeSn2 in Fe-43.9%Sn-10%Ge ternary alloy, whereas only (Cu) and (Pb) solid solution phases in Cu-35.5%Pb-5%Ge alloy under different undercoolings. In the process of rapid monotectic solidification, α-Fe and (Cu) phases grow in a dendritic mode, and the transition "dendrite→monotectic cell" happens when alloy undercoolings become sufficiently large. The dendrite growth velocities of α-Fe and (Cu) phases are found to increase with undercooling according to an exponential relation.

  18. Using Ge Secondary Phases to Enhance the Power Factor and Figure of Merit of Ge17Sb2Te20

    Science.gov (United States)

    Williams, Jared B.; Morelli, Donald T.

    2016-08-01

    Thermoelectric materials are the leading candidate today for applications in solid-state waste-heat recovery/cooling applications. Research and engineering has pushed the ZT, and overall conversion efficiency, of these materials to values which can be deemed practical for commercialization. However, many of the state-of-the-art thermoelectric materials of today utilize elements which are toxic, such as Ag, Pb, Tl, and Cd. Alloys of GeTe and Sb2Te3 were first explored for their applications in phase-change memory, because of their ability to rapidly alternate between crystalline and amorphous phases. Recently, these materials have been identified as materials with ZT (S 2 T/ρκ, where S is the Seebeck coefficient, ρ is the electrical resistivity, T is the operating temperature, and κ is the thermal conductivity) much greater than unity. In this work, the influence of elemental Ge as a secondary phase on transport in Ge17Sb2Te20 was explored. It was found that Ge introduces an additional scattering mechanism, which leads to increased electrical resistivity, Seebeck coefficient, and power factor values as high as 36 μW cm-1 K-2. The thermal conductivity was slightly reduced and the ZT was enhanced across the entire temperature range of measurement, with peak values greater than 2.

  19. Observation of Ge bottom cells in InGaP/InGaAs/Ge triple-junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Haeyong; Jung, Sanghyun; Kim, Changzoo; Jun, Donghwan; Kang, Hokwan [Korea Advanced Nano Fab Center, Suwon (Korea, Republic of); Kim, Hogyoung [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2014-10-15

    After growing InGaP/InGaAs/Ge triple-junction solar cells, we prepared two different Ge cells by etching down to the GaAs buffer layer (sample A) and the AlGaAs layer (sample B). Then, the photovoltaic properties of these two Ge cells were investigated under various light concentrations in order to find the factors affecting the overall performance of the triple-junction solar cells. Under concentrated light, the open-circuit voltage (V{sub OC} ), fill factor and conversion efficiency were higher for sample A than for sample B. The external quantum efficiency was shown to have a slightly higher value for sample A. Both the tunnel junction layer and the top contact resistance increased the series resistance, which also provided defects acting as leakage path. A comparison to previous works suggests that the conversion efficiency of Ge bottom, if present, is degraded marginally after the growth of the full structure of triple-junction solar cells.

  20. MnxGe1-x dilute magnetic semiconductor studied by XAFS

    Science.gov (United States)

    Ye, Jian; Jiang, Yong; Liu, Qinghua; Sun, Yu; Pan, Zhiyun; Wei, Shiqiang

    2009-11-01

    Fluorescence X-ray absorption fine structure (XAFS) technique was used to investigate the local structures of the doped Mn in the MnxGe1-x dilute magnetic semiconductors (DMSs) with different Mn content (x=0.07, 0.25, 0.36) prepared by magnetron cosputtering method. The results indicate that for the sample with low Mn content (x=0.07), the Mn atoms are mainly incorporated into the lattice of Ge, and locate at the substitutional sites of Ge atoms with the ratio of 75%. With the Mn content increasing to 0.25 or higher, only part of Mn atoms enter the lattice of Ge and the others exist in the form of the Mn5Ge3 phase whose content increases with the doped Mn concentration. It is found that, in the Mn0.07Ge0.93 the bond length of the first (Mn-Ge) shell is RMn-Ge = 2.50 Å, which is bigger than the first (Ge-Ge) shell distance in Ge by about 0.05 Å. These results imply that local structure expansion is induced by dilute Mn substituting into Ge sites.

  1. The Igex 76ge Neutrinoless Double-Beta Decay Experiment Prospects for Next Generation Experiments

    CERN Document Server

    Aalseth, C E; Cebrián, S; García, E; González, D; Hensley, W K; Irastorza, I G; Kirpichnikov, I V; Klimenko, A A; Miley, H S; Morales, A; Morales, J; De Solorzano, A O; Osetrov, S B; Pogosov, V S; Puimedón, J; Reeves, J H; Sarsa, M L; Smolnikov, A A; Starostin, A S; Tamanyan, A G; Vasenko, A A; Vasilev, S I; Villar, J A

    2002-01-01

    The International Germanium Experiment (IGEX) has analyzed 117 mole yr of 76Ge data from its isotopically enriched (86% 76Ge) germanium detectors. Applying pulse-shape discrimination (PSD) to the more recent data, the lower bound on the half-life for neutrinoless double-beta decay of 76Ge is: $T_{1/2}(0\

  2. Photoluminescence quenching effect by Si cap in n+ Ge on Si

    Science.gov (United States)

    Pan, H.; Takahashi, R.; Takinai, K.; Wada, K.

    2015-02-01

    Monolithically integrated Ge lasers on Si have long been one of the biggest challenges for electronic and photonic integration on Si Complementary Metal Oxide Semiconductor (CMOS) platform. The "last one mile" is to reduce the threshold current of the electrically pumped Ge-on-Si laser. We have studied the growth of heavily doped n type (n+) Ge and analyzed its photoluminescence (PL) characteristics of Ge with a Si cap and thermal oxide layers. It is found that the PL intensity of n+ Ge was significantly reduced by the cap and etching off the cap showed a ~100% recovery to the intensity of n+ Ge without the cap. Thermally oxidized n+ Ge, on the other hand, showed a ~50% increase in the PL intensity of uncapped n+ Ge. These finding indicated that capping of n+ Ge introduces non-radiative recombination centers due to defects (dislocations) to reduce the PL intensity, while oxidation passivates surface defects remained even on uncapped n+ Ge. Considering these, we have designed and fabricated an electrically pumped n+ Ge light emitting diode with no Si cap layer but oxidation. A broad luminescence of Ge at 1500-1700 nm has been demonstrated but yet lasing not observed.

  3. Why is GeV physics relevant in the age of the LHC?

    Energy Technology Data Exchange (ETDEWEB)

    Pennington, Michael R. [JLAB

    2014-02-01

    The contribution that Jefferson Lab has made, with its 6 GeV electron beam, and will make, with its 12 GeV upgrade, to our understanding of the way the fundamental interactions work, particularly strong coupling QCD, is outlined. The physics at the GeV scale is essential even in TeV collisions.

  4. Simultaneous suppression of ferromagnetism and superconductivity in UCoGe by Si substitution

    NARCIS (Netherlands)

    de Nijs, D.E.; Huy, N.T.; de Visser, A.

    2008-01-01

    We investigate the effect of substituting Si for Ge in the ferromagnetic superconductor UCoGe. dc-magnetization, ac-susceptibility, and electrical resistivity measurements on polycrystalline UCoGe1-xSix samples show that ferromagnetic order and superconductivity are progressively depressed with incr

  5. Ge nanoclusters in PECVD-deposited glass caused only by heat treatment

    DEFF Research Database (Denmark)

    Ou, Haiyan; Rørdam, Troels Peter; Rottwitt, Karsten

    2008-01-01

    This paper reports the formation of Ge nanoclusters in a multi-layer structure consisting of alternating thin films of Ge-doped silica glass and SiGe, deposited by plasma-enhanced chemical vapor deposition (PECVD) and post annealed at 1100 °C in N2 atmosphere. We studied the annealed samples by t...

  6. Surfactant-mediated epitaxy of thin germanium films on SiGe(001) virtual substrates

    Science.gov (United States)

    Schmidt, J.; Tetzlaff, D.; Bugiel, E.; Wietler, T. F.

    2017-01-01

    We report on the impact of a surfactant on the growth mode and strain relaxation of thin Ge films on Si0.21Ge0.79 virtual substrates grown by surfactant mediated epitaxy on Si(001) wafers. Ge epitaxy without surfactant results in island formation after deposition of only 5 nm Ge. A certain part of the strain in the Ge islands is relaxed via interfacial misfit dislocations, which are located within the core part of the islands. We discuss the possibilities for the occurrence of three-dimensional growth at low Ge layer thickness. The use of Sb as a surfactant suppresses three-dimensional islanding and enables the growth of smooth pseudomorphically strained Ge films on Si0.21Ge0.79(001) virtual substrates up to a thickness of 10 nm. At thicknesses higher than 20 nm, the films relax via the formation of a misfit dislocation network at the Ge/ Si1-xGex interface. The surface roughness of up to 30 nm thick layers is below 1.6 nm. Our experimental results corroborate the calculated thickness for plastic relaxation of Ge on Si1-xGex. The effect of the surfactant on the growth of the virtual substrate and on the subsequent growth of Ge on Si0.21Ge0.79 is discussed.

  7. Pressure variation of the valence band width in Ge: A self-consistent GW study

    DEFF Research Database (Denmark)

    Modak, Paritosh; Svane, Axel; Christensen, Niels Egede

    2009-01-01

    . In the present work we report results of quasiparticle self-consistent GW  (QSGW) band calculations for diamond- as well as β-tin-type Ge under pressure. For both phases we find that the band width increases with pressure. For β-tin Ge this agrees with experiment and density-functional theory, but for diamond Ge...

  8. Synthesis of crystalline Ge nanoclusters in PE-CVD-deposited SiO2 films

    DEFF Research Database (Denmark)

    Leervad Pedersen, T.P.; Skov Jensen, J.; Chevallier, J.

    2005-01-01

    The synthesis of evenly distributed Ge nanoclusters in plasma-enhanced chemical-vapour-deposited (PE-CVD) SiO2 thin films containing 8 at. % Ge is reported. This is of importance for the application of nanoclusters in semiconductor technology. The average diameter of the Ge nanoclusters can...

  9. High-Performance Deep SubMicron CMOS Technologies with Polycrystalline-SiGe Gates

    NARCIS (Netherlands)

    Ponomarev, Youri V.; Stolk, Peter A.; Salm, Cora; Schmitz, Jurriaan; Woerlee, P.H.

    2000-01-01

    The use of polycrystalline SiGe as the gate material for deep submicron CMOS has been investigated. A complete compatibility to standard CMOS processing is demonstrated when polycrystalline Si is substituted with SiGe (for Ge fractions below 0.5) to form the gate electrode of the transistors. Perfor

  10. Epitaxy relationships between Ge-islands and SiC(0 0 0 1)

    Energy Technology Data Exchange (ETDEWEB)

    Ait-Mansour, K. [Faculte des Sciences, LPSE, UMR CNRS 7014, 4, rue des Freres Lumiere, 68093 Mulhouse, Cedex (France)]. E-mail: k.ait-mansour@uha.fr; Dentel, D. [Faculte des Sciences, LPSE, UMR CNRS 7014, 4, rue des Freres Lumiere, 68093 Mulhouse, Cedex (France); Kubler, L. [Faculte des Sciences, LPSE, UMR CNRS 7014, 4, rue des Freres Lumiere, 68093 Mulhouse, Cedex (France); Diani, M. [Departement de Physique, Faculte des Sciences et Techniques, LSGM, BP 416, Tanger, Maroc (Morocco); Bischoff, J.L. [Faculte des Sciences, LPSE, UMR CNRS 7014, 4, rue des Freres Lumiere, 68093 Mulhouse, Cedex (France); Bolmont, D. [Faculte des Sciences, LPSE, UMR CNRS 7014, 4, rue des Freres Lumiere, 68093 Mulhouse, Cedex (France)

    2005-03-15

    Reflection high-energy electron diffraction (RHEED) has been used to determine epitaxy relationships and in-plane orientations between Ge and SiC(0 0 0 1). Three monolayers of Ge have been deposited at 500 deg. C on a graphitized SiC (6{radical}3 x 6{radical}3)R30 deg. reconstructed surface, this surface supporting epitaxial Ge island growth in a Volmer-Weber mode. Nucleation of relaxed Ge-islands gives rise to transmission electron diffraction patterns allowing to deduce that pure Ge grows according to only one epitaxy relationship Ge{l_brace}1 1 1{r_brace}//SiC(0 0 0 1). These {l_brace}1 1 1{r_brace}-Ge-islands have two in-plane orientations, a preferential one, Ge<-1-12>//SiC<1-100> and a minority one, Ge<-1-12>//SiC<10-10>, deduced one from the other by a 30 deg. rotation around the <1 1 1>-Ge (or [0 0 0 1]-SiC) growth axis. Due to the three-fold symmetry of the {l_brace}1 1 1{r_brace}-Ge plane, each in-plane orientation is degenerated into two twin orientations, differing by a 180 deg. angle around Ge<111>.

  11. High-Performance Deep SubMicron CMOS Technologies with Polycrystalline-SiGe Gates

    NARCIS (Netherlands)

    Ponomarev, Youri V.; Stolk, Peter A.; Salm, Cora; Schmitz, Jurriaan; Woerlee, P.H.

    2000-01-01

    The use of polycrystalline SiGe as the gate material for deep submicron CMOS has been investigated. A complete compatibility to standard CMOS processing is demonstrated when polycrystalline Si is substituted with SiGe (for Ge fractions below 0.5) to form the gate electrode of the transistors.

  12. Growth and Optical Properties of Direct Band Gap Ge/Ge0.87Sn0.13 Core/Shell Nanowire Arrays.

    Science.gov (United States)

    Assali, S; Dijkstra, A; Li, A; Koelling, S; Verheijen, M A; Gagliano, L; von den Driesch, N; Buca, D; Koenraad, P M; Haverkort, J E M; Bakkers, E P A M

    2017-03-08

    Group IV semiconductor optoelectronic devices are now possible by using strain-free direct band gap GeSn alloys grown on a Ge/Si virtual substrate with Sn contents above 9%. Here, we demonstrate the growth of Ge/GeSn core/shell nanowire arrays with Sn incorporation up to 13% and without the formation of Sn clusters. The nanowire geometry promotes strain relaxation in the Ge0.87Sn0.13 shell and limits the formation of structural defects. This results in room-temperature photoluminescence centered at 0.465 eV and enhanced absorption above 98%. Therefore, direct band gap GeSn grown in a nanowire geometry holds promise as a low-cost and high-efficiency material for photodetectors operating in the short-wave infrared and thermal imaging devices.

  13. Magnetocrystalline anisotropy of pure magnetic semiconductors of MnGeP2 and MnGeAs2: A first-principles study

    Science.gov (United States)

    Cha, Gi-Beom; Yun, Won Seok; Hong, Soon Cheol

    2016-12-01

    In this study, we use the all-electron full-potential linearized augmented plane wave method to investigate the magnetocrystalline anisotropies of pure magnetic MnGeP2 and MnGeAs2 semiconductors. Both MnGeP2 and MnGeAs2 have been calculated to be more stable in their antiferromagnetic (AFM) states than in their ferromagnetic (FM) states, with energy differences of about 230 and 190 meV/Mn, respectively. MnGeP2 and MnGeAs2 exhibit a positive EMCA (magnetization along the z axis) of +52.3 and +122.6 μeV/Mn in their AFM magnetic ground states with a negative EMCA (magnetization on the xy plane) of -71.1 and -177.8 μeV/Mn in their FM states. The EMCA behaviors are analyzed in terms of the electronic structure.

  14. Ultra-low temperature (≤300 °C) growth of Ge-rich SiGe by solid-liquid-coexisting annealing of a-GeSn/c-Si structures

    Science.gov (United States)

    Sadoh, Taizoh; Chikita, Hironori; Matsumura, Ryo; Miyao, Masanobu

    2015-09-01

    Ultra-low temperature (≤300 °C) growth of Ge-rich SiGe on Si substrates is strongly desired to realize advanced electronic and optical devices, which can be merged onto Si large-scale integrated circuits (LSI). To achieve this, annealing characteristics of a-GeSn/c-Si structures are investigated under wide ranges of the initial Sn concentrations (0%-26%) and annealing conditions (300-1000 °C, 1 s-48 h). Epitaxial growth triggered by SiGe mixing is observed after annealing, where the annealing temperatures necessary for epitaxial growth significantly decrease with increasing initial Sn concentration and/or annealing time. As a result, Ge-rich (˜80%) SiGe layers with Sn concentrations of ˜2% are realized by ultra-low temperature annealing (300 °C, 48 h) for a sample with the initial Sn concentration of 26%. The annealing temperature (300 °C) is in the solid-liquid coexisting temperature region of the phase diagram for Ge-Sn system. From detailed analysis of crystallization characteristics and composition profiles in grown layers, it is suggested that SiGe mixing is generated by a liquid-phase reaction even at ultra-low temperatures far below the melting temperature of a-GeSn. This ultra-low-temperature growth technique of Ge-rich SiGe on Si substrates is expected to be useful to realize next-generation LSI, where various multi-functional devices are integrated on Si substrates.

  15. Ultra-low temperature (≤300 °C) growth of Ge-rich SiGe by solid-liquid-coexisting annealing of a-GeSn/c-Si structures

    Energy Technology Data Exchange (ETDEWEB)

    Sadoh, Taizoh, E-mail: sadoh@ed.kyushu-u.ac.jp; Chikita, Hironori; Miyao, Masanobu [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Matsumura, Ryo [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); JSPS Research Fellow, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan)

    2015-09-07

    Ultra-low temperature (≤300 °C) growth of Ge-rich SiGe on Si substrates is strongly desired to realize advanced electronic and optical devices, which can be merged onto Si large-scale integrated circuits (LSI). To achieve this, annealing characteristics of a-GeSn/c-Si structures are investigated under wide ranges of the initial Sn concentrations (0%–26%) and annealing conditions (300–1000 °C, 1 s–48 h). Epitaxial growth triggered by SiGe mixing is observed after annealing, where the annealing temperatures necessary for epitaxial growth significantly decrease with increasing initial Sn concentration and/or annealing time. As a result, Ge-rich (∼80%) SiGe layers with Sn concentrations of ∼2% are realized by ultra-low temperature annealing (300 °C, 48 h) for a sample with the initial Sn concentration of 26%. The annealing temperature (300 °C) is in the solid-liquid coexisting temperature region of the phase diagram for Ge-Sn system. From detailed analysis of crystallization characteristics and composition profiles in grown layers, it is suggested that SiGe mixing is generated by a liquid-phase reaction even at ultra-low temperatures far below the melting temperature of a-GeSn. This ultra-low-temperature growth technique of Ge-rich SiGe on Si substrates is expected to be useful to realize next-generation LSI, where various multi-functional devices are integrated on Si substrates.

  16. A Systematic Study of the Optical and Electrical Properties of Ge1-ySny and Ge1-x-ySixSny Semiconductor Alloys

    Science.gov (United States)

    2014-03-27

    temperatures for the p- GeSn /n-Si (0.06% Sn) sample. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 5 Sheet carrier concentration...measured at RT in both air and vacuum as a function of etch depth for the p- GeSn /n-Si (0.06% Sn) sample...63 6 Measured sheet carrier concentration in cm-2 as a function of etch depth at selected temperatures for the p- GeSn /n-Si

  17. Impact of nitrogen plasma passivation on the Al/n-Ge contact

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Shumei; Mao, Danfeng [Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Ruan, Yujiao [Xiamen Institute of Measurement and Testing, Xiamen, Fujian 361004 (China); Xu, Yihong; Huang, Zhiwei; Huang, Wei [Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Chen, Songyan, E-mail: sychen@xmu.edu.cn [Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Li, Cheng; Wang, Jianyuan [Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Tang, Dingliang [College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China)

    2016-09-15

    Highlights: • A thin GeO{sub x}N{sub y} layer was formed by N{sub 2} plasma. • The principal parameters of N{sub 2} plasma treatment and additional post anneal have a great impact on the Al/n-Ge contact. • A model was proposed to explain the variation of Schottky barrier height. • The GeO{sub x}N{sub y} layer was also benefit to achieve a low leakage current density for HfO{sub 2}/Ge MOS capacitors. - Abstract: Severe Fermi level pinning at the interface of metal/n-Ge leads to the formation of a Schottky barrier. Therefore, a high contact resistance is introduced, debasing the performance of Ge devices. In this study, a Ge surface was treated by nitrogen plasma to form an ultra-thin Germanium oxynitride (GeO{sub x}N{sub y}) passivation layer. It was found that the Schottky barrier height (SBH) of metal/n-Ge contact was strongly modulated by the GeO{sub x}N{sub y} interlayer, indicating alleviation of Fermi-level pinning effect. By adjusting the principal parameters of N{sub 2} plasma treatment and additional post anneal, a Quasi-ohmic Al/n-Ge contact was achieved. Furthermore, the introduced GeO{sub x}N{sub y} layer gave extremely lower leakage current density of the gate stack for HfO{sub 2}/Ge devices. These results demonstrate that GeO{sub x}N{sub y} formed by N{sub 2} plasma would be greatly beneficial to the fabrication of the Ge-based devices.

  18. GeSi nanocrystals formed by high temperature annealing of GeO/SiO2 multilayers: structure and optical properties

    Science.gov (United States)

    Volodin, V. A.; Cherkov, A. G.; Vdovin, V. I.; Stoffel, M.; Rinnert, H.; Vergnat, M.

    2016-12-01

    The structural and optical properties of Ge and GeSi nanocrystals, formed by annealing of GeO/SiO2 multilayers have been investigated. According to Raman spectroscopy, the formation of pure Ge nanocrystals is observed after post growth annealing at 700 °C. Annealings at 800°C-900°C leads to the formation of intermixed GexSi1-x nanocrystals. High resolution transmission electron microscopy shows that the structure and the size of the nanocrystals strongly depend on annealing temperature. Spatial redistribution of Ge with the formation of large faceted clusters located near the Si substrate as well as GeSi intermixing at the substrate/film interface were observed. In the case of the sample containing 20 pairs of GeO/SiO2 layers annealed at 900 °C, some clusters exhibit a pyramid-like shape. FTIR absorption spectroscopy measurements demonstrate that intermixing between the GeO and SiO2 layers occurs leading to the formation of a SiGeO2 glass. Low temperature (10 K-100 K) photoluminescence was observed in the spectral range 1400-2000 nm for samples containing nanocrystals. The temperature dependence of the photoluminescence is studied.

  19. Comparative studies of clustering effect, electronic and optical properties for GePb and GeSn alloys with low Pb and Sn concentration

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Wenqi [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); School of Applied Science, Beijing Information Science and Technology University, Beijing 100101 (China); Cheng, Buwen, E-mail: cbw@semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Xue, Chunlai; Li, Chuanbo [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China)

    2014-06-15

    The first principle calculations are performed to study the impurity clustering effect, electronic and optical properties of GePb and GeSn alloys. The calculated results show that for a given concentration, the maximum impurity (Sn or Pb) clustered configuration is the most stable equilibrium structure (corresponding to the lowest total energy) which has the highest band gap. The calculated lattice constants and bulk modulus agree well with experimental and others’ theoretical values. The calculated band structures of virtual crystal structure and super-cell structure both indicate that GePb alloys undergo a transition from indirect to direct band gap as Pb concentration increases, and the transitional concentration is much lower than that of GeSn alloy. This conclusion indicates that GePb alloy can be a very prospective material for fabricating group-IV laser. The density of states and charge density maps of GeSn and GePb alloys are analyzed comparatively. For optical properties, the dielectric function, absorption spectrum, reflectivity, refractive index and loss function of Ge{sub 22}Sn{sub 2} and Ge{sub 22}Pb{sub 2} are investigated in detail.

  20. Nuclear Magnetic Resonance Studies of Tellurium and Antimony Bonding in Crystal Sb2Te3, GeTe, and Ge2Sb2Te5

    Science.gov (United States)

    Bobela, David C.; Taylor, P. Craig

    2008-10-01

    As a starting point in understanding the magnetic resonance data for amorphous Ge2Sb2Te5, the prototypical phase change material, we have used 121Sb and 125Te nuclear magnetic resonance (NMR) to study crystalline Sb2Te3, GeTe, and Ge2Sb2Te5. The frequency space data are affected by a quadrupole (121Sb only) and chemical shift (121Sb and 125Te) interaction, which reflect the bonding asymmetries occurring around each nuclei. The 125Te data indicate there are two distinct Te sites in Sb2Te3 and one Te site in the GeTe, in agreement with the known crystal structures. The Ge2Sb2Te5125Te data are less well-resolved, which is probably a consequence of the random arrangement of Sb/Ge atoms around the Te sites. Despite the lack of resolution, these data do correspond to the spectral positions and breadths observed in Sb2Te3 and GeTe, which suggests that Ge2Sb2Te5 contains similar Te bonding structures. The 121Sb data in Sb2Te3 show that the Sb sites have an approximately axially symmetric bonding environment. The Sb data in Ge2Sb2Te5 reveal that the average bonding structure of Sb is very different from the Sb sites occurring in Sb2Te3.

  1. Optical and X-ray photoelectron spectroscopy of PbGeO3 and Pb5Ge3O11 single crystals

    Indian Academy of Sciences (India)

    S C Sabharwal; S N Jha; Sangeeta

    2010-08-01

    Pb5Ge3O11 crystals are found to exhibit pale yellow colouration while PbGeO3 are colourless. X-ray photoelectron spectroscopy (XPS) measurements show lead deficiency in both the crystals. The results also reveal a stronger ionic character for PbGeO3 as compared to Pb5Ge3O11 crystal. The binding energy of Ge3 core level in the case of Pb5Ge3O11 crystal is found to be smaller than the binding energy of germanium oxide, thereby indicating the incomplete oxidation of Ge ions in the crystal lattice. On gamma ray irradiation, the transmission of both the crystals is observed to deteriorate uniformly over the entire wavelength range, which has been attributed to the oxidation of some of the lattice Pb ions. On gamma irradiation the changes observed in O1 core level energies for both the crystals are seen to be consistent with the changes noted in the Pb47/2 and Ge3 spectra. Interestingly, the results reveal oxidation of surface Ge atoms with atmospheric oxygen under gamma irradiation.

  2. Epitaxial Stabilization of Ferromagnetism in the Nanophase of FeGe

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Changgan [ORNL; Varela del Arco, Maria [ORNL; Kent, P. R. C. [University of Tennessee, Knoxville (UTK); Eisenbach, Markus [ORNL; Stocks, George Malcolm [ORNL; Torija Juana, Maria Asuncion [ORNL; Shen, Jian [ORNL; Weitering, Harm H [ORNL

    2006-01-01

    Epitaxial nanocrystals of FeGe have been stabilized on Ge(111). The nanocrystals assume a quasi-one-dimensional shape as they grow exclusively along the (110) direction of the Ge(111) substrate, culminating in a compressed monoclinic modification of FeGe. Whereas monoclinic FeGe is antiferromagnetic in the bulk, the nanowires are surprisingly strong ferromagnets below ~200 K with an average magnetic moment of 0.8?? per Fe atom. Density functional calculations indicate an unusual stabilization mechanism for the observed in the bulk while increased p-d hybridization suppresses the magnetic moments and stabilizes ferromagnetism.

  3. Polycrystalline GeSn thin films on Si formed by alloy evaporation

    Science.gov (United States)

    Kim, Munho; Fan, Wenjuan; Seo, Jung-Hun; Cho, Namki; Liu, Shih-Chia; Geng, Dalong; Liu, Yonghao; Gong, Shaoqin; Wang, Xudong; Zhou, Weidong; Ma, Zhenqiang

    2015-06-01

    Polycrystalline GeSn thin films on Si substrates with a Sn composition up to 4.5% have been fabricated and characterized. The crystalline structure, surface morphology, and infrared (IR) absorption coefficient of the annealed GeSn thin films were carefully investigated. It was found that the GeSn thin films with a Sn composition of 4.5% annealed at 450 °C possessed a desirable polycrystalline structure according to X-ray diffraction (XRD) analyses and Raman spectroscopy analyses. In addition, the absorption coefficient of the polycrystalline GeSn thin films in the IR region was significantly better than that of the single crystalline bulk Ge.

  4. 45 CFR 2541.240 - Matching or cost sharing.

    Science.gov (United States)

    2010-10-01

    ... supported by the same methods that the organization uses to support the allocability of regular personnel... fixed-price contract may count towards satisfying a cost sharing or matching requirement only if it..., and only depreciation or use allowances may be counted for donated equipment and buildings....

  5. The 750 GeV Diphoton Excess and SUSY

    Science.gov (United States)

    Heinemeyer, S.

    The LHC experiments ATLAS and CMS have reported an excess in the diphoton spectrum at ˜750 GeV. At the same time the motivation for Supersymmetry (SUSY) remains unbowed. Consequently, we review briefly the proposals to explain this excess in SUSY, focusing on "pure" (N)MSSM solutions. We then review in more detail a proposal to realize this excess within the NMSSM. In this particular scenario a Higgs boson with mass around 750 GeV decays to two light pseudo-scalar Higgs bosons. Via mixing with the pion these pseudo-scalars decay into a pair of highly collimated photons, which are identified as one photon, thus resulting in the observed signal.

  6. The 12 GeV Energy Upgrade at Jefferson Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Pilat, Fulvia C.

    2012-09-01

    Two new cryomodules and an extensive upgrade of the bending magnets at Jefferson Lab has been recently completed in preparation for the full energy upgrade in about one year. Jefferson Laboratory has undertaken a major upgrade of its flagship facility, the CW re-circulating CEBAF linac, with the goal of doubling the linac energy to 12 GeV. I will discuss here the main scope and timeline of the upgrade and report on recent accomplishments and the present status. I will then discuss in more detail the core of the upgrade, the new additional C100 cryomodules, their production, tests and recent successful performance. I will then conclude by looking at the future plans of Jefferson Laboratory, from the commissioning and operations of the 12 GeV CEBAF to the design of the MEIC electron ion collider.

  7. Giant Seebeck effect in Ge-doped SnSe

    Science.gov (United States)

    Gharsallah, M.; Serrano-Sánchez, F.; Nemes, N. M.; Mompeán, F. J.; Martínez, J. L.; Fernández-Díaz, M. T.; Elhalouani, F.; Alonso, J. A.

    2016-06-01

    Thermoelectric materials may contribute in the near future as new alternative sources of sustainable energy. Unprecedented thermoelectric properties in p-type SnSe single crystals have been recently reported, accompanied by extremely low thermal conductivity in polycrystalline samples. In order to enhance thermoelectric efficiency through proper tuning of this material we report a full structural characterization and evaluation of the thermoelectric properties of novel Ge-doped SnSe prepared by a straightforward arc-melting method, which yields nanostructured polycrystalline samples. Ge does not dope the system in the sense of donating carriers, yet the electrical properties show a semiconductor behavior with resistivity values higher than that of the parent compound, as a consequence of nanostructuration, whereas the Seebeck coefficient is higher and thermal conductivity lower, favorable to a better ZT figure of merit.

  8. Growth and Characterization of Bulk GeSi Solid Solutions

    Science.gov (United States)

    Ritter, Timothy M.

    1999-01-01

    In this work we have grown and characterized several GeSi samples in order to investigate the effects that Silicon concentration, applied magnetic field, and liquid encapsulation have on crystalline quality. Characterization techniques include NDIC microscopy and microprobe spectroscopy. Two samples were grown with a Silicon concentration of approximately 3% and are compared to previous growths having a Silicon fraction of approximately 5%. Growth conditions for one of these samples was varied with the presence of an external applied magnetic field to investigate the possibility of magnetic field damping. A comparison between these two ingots, and with previously grown material, revealed no clear improvement in sample crystalline quality. Three additional samples were grown using a CaCl2 liquid encapsulation technique that produced GeSi material with improved structural quality over previous samples. Comparisons to prior non-encapsulation grown material, details of our methodology, and suggestions for further improvements are discussed.

  9. Proton-proton Scattering Above 3 GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    A. Sibirtsev, J. Haidenbauer, H.-W. Hammer S. Krewald ,Ulf-G. Meissner

    2010-01-01

    A large set of data on proton-proton differential cross sections, analyzing powers and the double-polarization parameter A{sub NN} is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3 GeV/c to 50 GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the {rho}, {omega}, f{sub 2}, and a{sub 2} trajectories and single-Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model.

  10. Itinerant magnetism in metallic CuFe2Ge2.

    Directory of Open Access Journals (Sweden)

    K V Shanavas

    Full Text Available Theoretical calculations are performed to understand the electronic structure and magnetic properties of CuFe2Ge2. The band structure reveals large electron density N(EF at the Fermi level suggesting a strong itinerant character of magnetism. The Fermi surface is dominated by two dimensional sheet like structures, with potentially strong nesting between them. The magnetic ground state appears to be ferromagnetic along a and antiferromagnetic in other directions. These results show that CuFe2Ge2 is an antiferromagnetic metal, with similarities to the Fe-based superconductors; such as magnetism with substantial itinerant character and coupling between magnetic order and electrons at the Fermi energy.

  11. High temperature XRD of Cu2GeSe3

    Science.gov (United States)

    Premkumar D., S.; Chetty, Raju; Malar, P.; Mallik, Ramesh Chandra

    2015-06-01

    The Cu2GeSe3 is prepared by solid state synthesis method. The high temperature XRD has been done at different temperature from 30 °C to 450 °C. The reitveld refinement confirms Cu2GeSe3 phase and orthorhombic crystal structure. The lattice constants are increasing with increase in the temperature and their rate of increase with respect to temperature are used for finding the thermal expansion coefficient. The calculation of the linear and volume coefficient of thermal expansion is done from 30 °C to 400 °C. Decrease in the values of linear expansion coefficients with temperature are observed along a and c axis. Since thermal expansion coefficient is the consequence of the distortion of atoms in the lattice; this can be further used to find the minimum lattice thermal conductivity at given temperature.

  12. Abelian Hidden Sectors at a GeV

    Energy Technology Data Exchange (ETDEWEB)

    Morrissey, David E.; Poland, David; /Harvard U.; Zurek, Kathryn; /Fermilab /Michigan U.

    2009-04-16

    We discuss mechanisms for naturally generating GeV-scale hidden sectors in the context of weak-scale supersymmetry. Such low mass scales can arise when hidden sectors are more weakly coupled to supersymmetry breaking than the visible sector, as happens when supersymmetry breaking is communicated to the visible sector by gauge interactions under which the hidden sector is uncharged, or if the hidden sector is sequestered from gravity-mediated supersymmetry breaking. We study these mechanisms in detail in the context of gauge and gaugino mediation, and present specific models of Abelian GeV-scale hidden sectors. In particular, we discuss kinetic mixing of a U(1){sub x} gauge force with hypercharge, singlets or bi-fundamentals which couple to both sectors, and additional loop effects. Finally, we investigate the possible relevance of such sectors for dark matter phenomenology, as well as for low- and high-energy collider searches.

  13. GeSbTe deposition for the PRAM application

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Junghyun [Nano Fabrication Center, SAIT, Suwon, P.O. Box 111 (Korea, Republic of); Choi, Sangjoon [Nano Fabrication Center, SAIT, Suwon, P.O. Box 111 (Korea, Republic of); Lee, Changsoo [Nano Fabrication Center, SAIT, Suwon, P.O. Box 111 (Korea, Republic of); Kang, Yoonho [Nano Fabrication Center, SAIT, Suwon, P.O. Box 111 (Korea, Republic of); Kim, Daeil [School of Materials Science and Engineering. University of Ulsan, San 29, Mugeo-Dong, Nam-Gu, Ulsan 680-749 (Korea, Republic of)]. E-mail: dkim84@mail.ulsan.ac.kr

    2007-02-15

    GeSbTe (GST) chalcogenide thin films for the phase-change random access memory (PRAM) were deposited by an atomic layer deposition (ALD) process. New precursors for GST thin films made with an ALD process were synthesized. Among the synthesized precursors, Ge(N(CH{sub 3}){sub 2}){sub 4}, Sb(N(CH{sub 3}){sub 2}){sub 4}, and Te(i-Pr){sub 2} (i-Pr = iso-propyl) were selected. Using the above precursors, GST thin films were deposited using an H{sub 2} plasma-assisted ALD process. Film resistivity abruptly changed after an N{sub 2} annealing process above a temperature of 350 deg. C. Cross-sectional scanning electron microscope (SEM) photographs of the GST films on the patterned substrate with aspect ratio of 7 shows that the step coverage is about 90%.

  14. First measurement of {sup 60}Ge β-decay

    Energy Technology Data Exchange (ETDEWEB)

    Ciemny, A.A.; Dominik, W.; Janas, Z.; Kuich, M.; Mazzocchi, C.; Miernik, K.; Pfuetzner, M.; Pomorski, M.; Cwiok, M.; Korgul, A. [University of Warsaw, Faculty of Physics, Warsaw (Poland); Ginter, T.; Bazin, D.; Baumann, T.; Crider, B.P.; Kwan, E.; Pereira, J.; Sumithrarachchi, C. [Michigan State University, National Superconducting Cyclotron Laboratory, East Lansing, MI (United States); Grzywacz, R. [University of Tennessee, Department of Physics and Astronomy, Knoxville, TN (United States); Oak Ridge National Laboratory, Oak Ridge, TN (United States); Bezbakh, A. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Go, S.; Kolos, K.; Xiao, Y. [University of Tennessee, Department of Physics and Astronomy, Knoxville, TN (United States); Kaminski, G. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Institute of Nuclear Physics PAN, Cracow (Poland); Liddick, S.N. [Michigan State University, National Superconducting Cyclotron Laboratory, East Lansing, MI (United States); Michigan State University, Department of Chemistry, East Lansing, MI (United States); Paulauskas, S.V. [Michigan State University, National Superconducting Cyclotron Laboratory, East Lansing, MI (United States); University of Tennessee, Department of Physics and Astronomy, Knoxville, TN (United States); Rykaczewski, K.P. [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2016-04-15

    The N = 28 isotone {sup 60}Ge, T{sub z} = -2, was produced and selected among the products of the fragmentation reaction of a {sup 78}Kr beam at 150 MeV/nucleon and a Be target by means of the A1900 fragment separator at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). Its decay was studied for the first time using the optical time projection chamber. The β-decay of {sup 60}Ge was found to be dominated by β-delayed proton emission, with a branching of ∼ 100 % and half-life T{sub 1/2} = 20{sub -5}{sup +7} ms. (orig.)

  15. The 750 GeV diphoton excess and SUSY

    CERN Document Server

    Heinemeyer, S

    2016-01-01

    The LHC experiments ATLAS and CMS have reported an excess in the diphoton spectrum at \\sim 750 GeV. At the same time the motivation for Supersymmetry (SUSY) remains unbowed. Consequently, we review briefly the proposals to explain this excess in SUSY, focusing on "pure" (N)MSSM solutions. We then review in more detail a proposal to realize this excess within the NMSSM. In this particular scenario a Higgs boson with mass around 750 GeV decays to two light pseudo-scalar Higgs bosons. Via mixing with the pion these pseudo-scalars decay into a pair of highly collimated photons, which are identified as one photon, thus resulting in the observed signal.

  16. New Forces and the 750 GeV Resonance

    CERN Document Server

    Duerr, Michael; Smirnov, Juri

    2016-01-01

    Recently, the ATLAS and CMS collaborations have pointed out the possible existence of a new resonance with a mass around 750 GeV. We investigate the possibility to identify this new resonance with a spin zero field responsible for the breaking of a new gauge symmetry. We focus on a simple theory where the baryon number is a local symmetry spontaneously broken at the low scale. In this context new vector-like quarks are needed to cancel all baryonic anomalies and define the production mechanism and decays of the new Higgs at the LHC. Assuming the existence of the new Higgs with a mass of 750 GeV at the LHC we find an upper bound on the symmetry breaking scale. Therefore, one expects that a new force associated with baryon number could be discovered at the LHC.

  17. Evaporation-based Ge/.sup.68 Ga Separation

    Science.gov (United States)

    Mirzadeh, Saed; Whipple, Richard E.; Grant, Patrick M.; O'Brien, Jr., Harold A.

    1981-01-01

    Micro concentrations of .sup.68 Ga in secular equilibrium with .sup.68 Ge in strong aqueous HCl solution may readily be separated in ionic form from the .sup.68 Ge for biomedical use by evaporating the solution to dryness and then leaching the .sup.68 Ga from the container walls with dilute aqueous solutions of HCl or NaCl. The chloro-germanide produced during the evaporation may be quantitatively recovered to be used again as a source of .sup.68 Ga. If the solution is distilled to remove any oxidizing agents which may be present as impurities, the separation factor may easily exceed 10.sup.5. The separation is easily completed and the .sup.68 Ga made available in ionic form in 30 minutes or less.

  18. Crystal structure determination of CoGeTe from powder diffraction data

    Energy Technology Data Exchange (ETDEWEB)

    Laufek, F. [Czech Geological Survey, Geologicka 6, 15200 Praha 5 (Czech Republic)], E-mail: laufek@cgu.cz; Navratil, J. [Joint Laboratory of Solid State Chemistry of IMC AS CR and University of Pardubice, Studentska 84, 53210 Pardubice (Czech Republic); Plasil, J. [Faculty of Science, Charles University, Albertov 6, 12843 Praha 2 (Czech Republic); Plechacek, T. [Joint Laboratory of Solid State Chemistry of IMC AS CR and University of Pardubice, Studentska 84, 53210 Pardubice (Czech Republic)

    2008-07-28

    The crystal structure of cobalt germanium telluride CoGeTe has been determined by direct methods using integrate intensities of conventional X-ray powder diffraction data and subsequently refined with the Rietveld method. The title compound was prepared by heating of stoichiometric amount of Co, Ge and Te in silica glass tube at 670 deg. C. CoGeTe adopts orthorhombic symmetry, space group Pbca with unit cell parameters a = 6.1892(4) A, b = 6.2285(4) A, c = 11.1240(6) A, V = 428.8(1) A{sup 3} and Z = 8. Its crystal structure is formed by [CoGe{sub 3}Te{sub 3}] octahedra sharing both edges and corners. CoGeTe represents a ternary ordered variant of {alpha}-NiAs{sub 2} type structure. An important feature present in CoGeTe is an occurrence of short Co-Co distance across the shared edge of [CoGe{sub 3}Te{sub 3}] octahedra. Differential thermal analysis (DTA) has revealed that CoGeTe melts incongruently at about 725 deg. C; CoGeTe decomposes into GeTe, CoGe and CoTe{sub 2}. Temperature dependence of the electrical conductivity and value of Seebeck coefficient at 300 K are also reported.

  19. Temperature Sensor Based on Ge-Doped Microstructured Fibers

    Directory of Open Access Journals (Sweden)

    Salvador Torres-Peiró

    2009-01-01

    Full Text Available The fundamental mode cutoff properties of Ge-doped microstructured fibers, filled with a liquid, permit the implementation of wavelength- and amplitude-encoded temperature sensors with an ultra-high sensitivity. The cutoff wavelength changes with temperature, and the thermo-optic coefficient of the liquid determines the sensitivity of the sensor. Sensitivity as high as 25 nm/∘C is reported. In addition, simple amplitude interrogation techniques can be implemented using the same sensor heads.

  20. NASA/GE Collaboration on Open Rotors - High Speed Testing

    Science.gov (United States)

    VanZante, Dale E.

    2011-01-01

    A low-noise open rotor system is being tested in collaboration with General Electric and CFM International, a 50/50 joint company between Snecmaand GE. Candidate technologies for lower noise will be investigated as well as installation effects such as pylon integration. Current test status for the 8x6 SWT high speed testing is presented as well as future scheduled testing which includes the FAA/CLEEN test entry. The tunnel blockage and propeller thrust calibration configurations are shown.

  1. Hole transport simulations in SiGe cascade quantum wells

    Science.gov (United States)

    Ikonić, Z.; Harrison, P.; Kelsall, R. W.

    2004-03-01

    Hole transport in p-Si/SiGe quantum well cascade structures has been analyzed using a rate equation method with thermal balancing (self-consistent energy balance method). The carrier and energy relaxation due to alloy disorder, acoustic and optical phonon scattering are included. The model includes the in-plane k-space anisotropy. The results are compared to those obtained from Monte Carlo simulations and from the basic particle rate equation method.

  2. On certain Rankin-Selberg integrals on $GE_{6}$

    OpenAIRE

    2008-01-01

    In this paper we begin the study of two Rankin-Selberg integrals defined on the exceptional group of type $GE_{6}$. We show that each factorizes and that the contribution from the unramified places is, in one case, the degree 54 Euler product $L^{S}(\\pi \\times \\tau, E_{6} \\times GL_{2}, s)$ and in the other case the degree 30 Euler product $L^{S}(\\pi \\times \\tau, \\wedge^{2} \\times GL_{2}, s)$.

  3. Neutrinoless double beta decay searches with 76Ge

    CERN Document Server

    CERN. Geneva

    2017-01-01

    The search for neutrinoless double beta decay might be the only window to observe lepton number violation. Its observation would favour the leptogenesis mechanism for the explanation of the baryon asymmetry of the universe and is therefore considered to be of highest relevance. The isotope 76Ge has historically been most important for this search and the ongoing experiment GERDA has the lowest background of all experiments in the field. The talk reviews the motivation, the current status of experiments and future programs.

  4. Electrical characterization Of SiGe thin films

    OpenAIRE

    1991-01-01

    An apparatus for measuring electrical resistivity and Hall coefficient on both thin films and bulk material over a temperature range of 300K to 1300K has been built. A unique alumina fixture, with four molybdenum probes, allows arbitrarily shaped samples, up to 2.5 cm diameter, to be measured using van der Pauw's method. The system is fully automated and is constructed with commercially available components. Measurements of the electrical properties of doped and undoped Si-Ge thin films, gro...

  5. Numerical simulation of microstructure of the GeSi alloy

    Energy Technology Data Exchange (ETDEWEB)

    Rasin, I.

    2006-09-08

    The goal of this work is to investigate pattern formation processes on the solid-liquid interface during the crystal growth of GeSi. GeSi crystals with cellular structure have great potential for applications in -ray and neutron optics. The interface patterns induce small quasi-periodic distortions of the microstructure called mosaicity. Existence and properties of this mosaicity are important for the application of the crystals. The properties depend on many factors; this dependence, is currently not known even not qualitatively. A better understanding of the physics near the crystal surface is therefore required, in order to optimise the growth process. There are three main physical processes in this system: phase-transition, diffusion and melt flow. Every process is described by its own set of equations. Finite difference methods and lattice kinetic methods are taken for solving these governing equations. We have developed a modification of the kinetic methods for the advectiondiffusion and extended this method for simulations of non-linear reaction diffusion equations. The phase-field method was chosen as a tool for describing the phase-transition. There are numerous works applied for different metallic alloys. An attempt to apply the method directly to simulation GeSi crystal growth showed that this method is unstable. This instability has not been observed in previous works due to the much smaller scale of simulations. We introduced a modified phase-field scheme, which enables to simulate pattern formation with the scale observed in experiment. A flow in the melt was taken in to account in the numerical model. The developed numerical model allows us to investigate pattern formation in GeSi crystals. Modelling shows that the flow near the crystal surface has impact on the patterns. The obtained patterns reproduce qualitatively and in some cases quantitatively the experimental results. (orig.)

  6. Heating nuclei with 8 GeV/c antiprotons

    CERN Document Server

    Lefort, T; Hsi, W C; Beaulieu, L; Viola, V E; Pienkowski, L; Korteling, R G; Leforest, R; Martin, E; Ramakrishnan, E; Rowland, D; Ruangma, A; Winchester, E M; Yennello, S J; Gushue, S; Remsberg, L P; Back, B B; Breuer, H

    1999-01-01

    Studies of the heating effect of 8 GeV/c pi sup - and antiproton beams incident on a sup 1 sup 9 sup 7 Au nucleus have been conducted at Brookhaven AGS accelerator with the Indiana Silicon Sphere 4 pi detector array. Enhanced energy deposition for antiprotons relative to negative pions and protons in this energy regime is observed. The results are consistent with predictions of an intranuclear cascade code.

  7. The European 400 GeV proton synchrotron

    CERN Document Server

    Middelkoop, Willem Cornelis

    1977-01-01

    On 19th February 1971, CERN decided to build a super proton synchrotron at a cost of 1150*10/sup 6/ Swiss francs. The design target of 400 GeV with a beam intensity of 10/sup 13/ protons/pulse was reached on the 4th of November 1976 within the original budget, allowing for inflation. The technical aspects of the SPS are reviewed, together with operating experience since May 1976. (2 refs).

  8. Measurements of Neutrino Cross Sections Near 1 GeV

    CERN Document Server

    Wascko, M O

    2009-01-01

    We summarise recent neutrino and antineutrino measurements near 1 GeV by the K2K, MiniBooNE and SciBooNE collaborations. We focus on experimental methods and note discrepancies between the most commonly used models for neutrino-nucleus interactions and recent high statistics observations of charged-current quasi-elastic scattering as well as charged and neutral current pion production on carbon and oxygen. We discuss possible directions for future measurements.

  9. Development of Microwave SiGe Heterojunction Bipolar Transistors

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The microwave SiGe Heterojunction Bipolar Transistors (HBT) were fabricated by the material grown with home-made high vacuum/rapid thermal processing chemical vapor deposition equipment. The HBTs show good performance and industrial use value. The current gain is beyond 100;the breakdown voltage BVceo is 3.3V,and the cut-off frequency is 12.5GHz which is measured in packaged form.

  10. Nanocrystals formation and fractal microstructural assessment in Au/Ge bilayer films upon annealing

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.W. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)]. E-mail: cnzwchen@yahoo.com.cn; Lai, J.K.L. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China); Shek, C.H. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China); Chen, H.D. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)

    2005-08-31

    Nanocrystals formation and fractal microstructural assessment in Au/Ge bilayer films upon annealing have been investigated by transmission electron microscopy and high-resolution transmission electron microscopy observations. Experimental results indicated that the microstructure of the metal Au film plays an important role in metal-induced crystallization for Au/Ge bilayer films upon annealing. Synchronously, the crystallization processes of amorphous Ge accompanied by the formation of Ge fractal clusters, which were composed of Ge nanocrystals. We found that the grain boundaries of polycrystalline Au film were the initial nucleation sites of Ge nanocrystals. High-resolution transmission electron microscopy observations showed successive nucleation of amorphous Ge at Au grain boundaries near fractal tips. The crystallization process was suggested to be diffusion controlled and a random successive nucleation and growth mechanism.

  11. New approach to the growth of low dislocation relaxed SiGe material

    Science.gov (United States)

    Powell, A. R.; Iyer, S. S.; LeGoues, F. K.

    1994-04-01

    In this growth process a new strain relief mechanism operates, whereby the SiGe epitaxial layer relaxes without the generation of threading dislocations within the SiGe layer. This is achieved by depositing SiGe on an ultrathin silicon on insulator (SOI) substrate with a superficial silicon thickness less than the SiGe layer thickness. Initially, the thin Si layer is put under tension due to an equalization of the strain between the Si and SiGe layers. Thereafter, the strain created in the thin Si layer relaxes by plastic deformation. Since the dislocations are formed and glide in the thin Si layer, no threading dislocation is ever introduced in to the upper SiGe material, which appeared dislocation free to the limit of the cross sectional transmission electron microscopy analysis. We thus have a method for producing very low dislocation, relaxes SiGe films with the additional benefit of an SOI substrate.

  12. Formation of GeSn alloy on Si(100) by low-temperature molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Talochkin, A. B., E-mail: tal@isp.nsc.ru [A. V. Rzhanov Institute of Semiconductor Physics, Lavrentyev Avenue 13, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Mashanov, V. I. [A. V. Rzhanov Institute of Semiconductor Physics, Lavrentyev Avenue 13, Novosibirsk 630090 (Russian Federation)

    2014-12-29

    GeSn alloys grown on Si(100) by the low-temperature (100 °C) molecular beam epitaxy are studied using scanning tunneling microscopy and Raman spectroscopy. It is found that the effect of Sn as a surfactant modifies substantially the low-temperature growth mechanism of Ge on Si. Instead of the formation of small Ge islands surrounded by amorphous Ge, in the presence of Sn, the growth of pure Ge islands appears via the Stranski-Krastanov growth mode, and a partially relaxed Ge{sub 1−x}Sn{sub x} alloy layer with the high Sn-fraction up to 40 at. % is formed in the area between them. It is shown that the observed growth mode induced by high surface mobility of Sn and the large strain of the pseudomorphic state of Ge to Si ensures the minimum elastic-strain energy of the structure.

  13. Growth and applications of GeSn-related group-IV semiconductor materials

    Science.gov (United States)

    Zaima, Shigeaki; Nakatsuka, Osamu; Taoka, Noriyuki; Kurosawa, Masashi; Takeuchi, Wakana; Sakashita, Mitsuo

    2015-08-01

    We review the technology of Ge1-xSnx-related group-IV semiconductor materials for developing Si-based nanoelectronics. Ge1-xSnx-related materials provide novel engineering of the crystal growth, strain structure, and energy band alignment for realising various applications not only in electronics, but also in optoelectronics. We introduce our recent achievements in the crystal growth of Ge1-xSnx-related material thin films and the studies of the electronic properties of thin films, metals/Ge1-xSnx, and insulators/Ge1-xSnx interfaces. We also review recent studies related to the crystal growth, energy band engineering, and device applications of Ge1-xSnx-related materials, as well as the reported performances of electronic devices using Ge1-xSnx related materials.

  14. Process modules for GeSn nanoelectronics with high Sn-contents

    Science.gov (United States)

    Schulte-Braucks, C.; Glass, S.; Hofmann, E.; Stange, D.; von den Driesch, N.; Hartmann, J. M.; Ikonic, Z.; Zhao, Q. T.; Buca, D.; Mantl, S.

    2017-02-01

    This paper systematically studies GeSn n-FETs, from individual process modules to a complete device. High-k gate stacks and NiGeSn metallic contacts for source and drain are characterized in independent experiments. To study both direct and indirect bandgap semiconductors, a range of 0-14.5 at.% Sn-content GeSn alloys are investigated. Special emphasis is placed on capacitance-voltage (C-V) characteristics and Schottky-barrier optimization. GeSn n-FET devices are presented including temperature dependent I-V characteristics. Finally, as an important step towards implementing GeSn in tunnel-FETs, negative differential resistance in Ge0.87Sn0.13 tunnel-diodes is demonstrated at cryogenic temperatures. The present work provides a base for further optimization of GeSn FETs and novel tunnel FET devices.

  15. SiGe-on-insulator substrate fabricated by low energy oxygen implantation

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, Yukari E-mail: yukari@jfcc.or.jp; Saito, T.; Shibata, N.; Fukatsu, S

    1999-01-01

    Nanometer order SiGe-on-insulator substrates have become accessible by using the separation-by-implanted-oxygen (SIMOX) technique. Low energy (25 keV) oxygen ion (O{sup +}) implantation was performed on a strain-relieved Si{sub 0.82}Ge{sub 0.18} substrate. The dose window for a SOI structure was found by cross-sectional imaging to be 2-2.5x10{sup 17} cm{sup -2}. The Ge composition of the top SiGe layer is controllable by post-implant annealing. Fabrication of SiGe-on-insulator substrates on a thick pseudomorphic Si{sub 0.82}Ge{sub 0.18} grown on Si(1 0 0) is also demonstrated. The results hold promise for a low-cost and high-throughput SiGe-SIMOX.

  16. Activation and thermal stability of ultra-shallow B+-implants in Ge

    DEFF Research Database (Denmark)

    Yates, B. R.; Darby, B. L.; Petersen, Dirch Hjorth;

    2012-01-01

    The activation and thermal stability of ultra-shallow B+ implants in crystalline (c-Ge) and preamorphized Ge (PA-Ge) following rapid thermal annealing was investigated using micro Hall effect and ion beam analysis techniques. The residual implanted dose of ultra-shallow B+ implants in Ge...... from 5.0 × 1013 to 5.0 × 1015 cm-2 was studied using micro Hall effect measurements after annealing at 400-600 °C for 60 s. For both c-Ge and PA-Ge, a large fraction of the implanted dose is rendered inactive due to the formation of a presumable B-Ge cluster. The B lattice location in samples annealed...

  17. High-Quality Single Crystalline Ge(111) Growth on Si(111) Substrates by Solid Phase Epitaxy

    Institute of Scientific and Technical Information of China (English)

    SUN Bing; CHANG Hu-Dong; LU Li; LIU Hong-Gang; WU De-Xin

    2012-01-01

    Heterogeneous integration of crystalline Ge layers on cleaned and H-terminated Si(111) substrates are demonstrated by employing a combination of e-beam evaporation and solid phase epitaxy techniques. High-quality single crystalline Ge(111) layers on Si(111) substrates with a smooth Ge surface and an abrupt interface between Ge and Si are obtained.An XRD rocking curve scan of the Ge(111) diffraction peak shovs a FWHM of only 260 arcsec for a 50-nm-thick Ge layer annealed at 600℃ with a ramp-up rate of 20℃/s and a holding time of 1 min. The AFM images exhibit that the rms surface roughness of all the crystalline Ge layers are less than 2.1 nm.

  18. Growth and applications of GeSn-related group-IV semiconductor materials.

    Science.gov (United States)

    Zaima, Shigeaki; Nakatsuka, Osamu; Taoka, Noriyuki; Kurosawa, Masashi; Takeuchi, Wakana; Sakashita, Mitsuo

    2015-08-01

    We review the technology of Ge1-x Sn x -related group-IV semiconductor materials for developing Si-based nanoelectronics. Ge1-x Sn x -related materials provide novel engineering of the crystal growth, strain structure, and energy band alignment for realising various applications not only in electronics, but also in optoelectronics. We introduce our recent achievements in the crystal growth of Ge1-x Sn x -related material thin films and the studies of the electronic properties of thin films, metals/Ge1-x Sn x , and insulators/Ge1-x Sn x interfaces. We also review recent studies related to the crystal growth, energy band engineering, and device applications of Ge1-x Sn x -related materials, as well as the reported performances of electronic devices using Ge1-x Sn x related materials.

  19. Ge Hong. Famous Daoist Thinker & Practical Martial Artist

    Directory of Open Access Journals (Sweden)

    Stanley E. Henning

    2012-07-01

    Full Text Available Ge Hong (284-363 CE was an important intellectual figure of his time. He is known primarily for his interest in Daoist pursuits, including alchemy, as discussed in his writings titled One Who Embraces Simplicity (Baopuzi. However, the fact that he was also a military officer, who had practiced several weapons styles and who provides valuable insights into Chinese martial arts practices, has generally been ignored. This short article will attempt to outline Ge Hong’s contributions to our understanding of the role of martial arts in Chinese culture and society based on his personal experience and observations. Ge Hong viewed the martial arts as practical skills related to hunting (archery and self-defense, not Daoist pursuits, and he mentions that some of these skills could even be seen in children’s play. His reference to Cao Pi (Emperor of Wei, 220-226 CE sparring with General Deng Zhan reflects the place of martial arts among leadership in the political military system of early imperial China (206 BCE-960 CE. His explanation of oral formulas (koujue is indicative of the secrecy maintained by martial artists concerning individual techniques. 

  20. Analysis of Si/SiGe Heterostructure Solar Cell

    Directory of Open Access Journals (Sweden)

    Ashish Kumar Singh

    2014-01-01

    Full Text Available Sunlight is the largest source of carbon-neutral energy. Large amount of energy, about 4.3 × 1020 J/hr (Lewis, 2005, is radiated because of nuclear fusion reaction by sun, but it is unfortunate that it is not exploited to its maximum level. Various photovoltaic researches are ongoing to find low cost, and highly efficient solar cell to fulfil looming energy crisis around the globe. Thin film solar cell along with enhanced absorption property will be the best, so combination of SiGe alloy is considered. The paper presented here consists of a numerical model of Si/Si1-xGex heterostructure solar cell. The research has investigated characteristics such as short circuit current density (Jsc, generation rate (G, absorption coefficient (α, and open circuit voltage (Voc with optimal Ge concentration. The addition of Ge content to Si layer will affect the property of material and can be calculated with the use of Vegard’s law. Due to this, short circuit current density increases.

  1. Exclusive processes at JLab at 6 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Andrey [Univ. of Connecticut, Storrs, CT (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2015-01-01

    Deeply virtual exclusive reactions provide a unique opportunity to probe the complex internal structure of the nucleon. They allow to access information about the correlations between parton transverse spatial and longitudinal momentum distributions from experimental observables. Dedicated experiments to study Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP) have been carried out at Jefferson Lab using continuous electron beam with energies up to 6 GeV. Unpolarized cross sections, beam, target and double spin asymmetries have been measured for DVCS as well as for π0 exclusive electroproduction. The data from Hall B provide a wide kinematic coverage with Q2=1-4.5 GeV2, xB=0.1-0.5, and -t up to 2 GeV2. Hall A data have limited kinematic range partially overlapping with Hall B kinematics but provide a high accuracy measurements. Scaling tests of the DVCS cross sections provide solid evidence of twist-2 dominance, which makes chiral-even GPDs accessible even at modest Q2. We will discuss the interpretation of these data in terms of Generalized Parton Distributions (GPDs) model. Successful description of the recent CLAS π0 exclusive production data within the framework of the GPD-based model provides a unique opportunity to access the chiral-odd GPDs.

  2. Gamma-Ray Bursts Above 1 GeV

    CERN Document Server

    Baring, M G

    1997-01-01

    One of the principal results obtained by the Compton Gamma Ray Observatory relating to the study of gamma-ray bursts was the detection by the EGRET instrument of energetic ($>$100 MeV) photons from a handful of bright bursts. The most extreme of these was the single 18 GeV photon from the GRB940217 source. Given EGRET's sensitivity and limited field of view, the detection rate implies that such high energy emission may be ubiquitous in bursts. Hence expectations that bursts emit out to at least TeV energies are quite realistic, and the associated target-of-opportunity activity of the TeV gamma-ray community is well-founded. This review summarizes the observations and a handful of theoretical models for generating GeV--TeV emission in bursts sources, outlining possible ways that future positive detections could discriminate between different scenarios. The power of observations in the GeV--TeV range to distinguish between spectral structure intrinsic to bursts and that due to the intervening medium between sou...

  3. Electric properties of Ge quantum dot embedded in Si matrix

    Institute of Scientific and Technical Information of China (English)

    MA Xi-ying; SHI Wei-lin

    2005-01-01

    The electric characteristics of Ge quantum dot grown by molecular beam epitaxy in Si matrix were investigated by admittance spectroscopy and deep level transient spectroscopy. The admittance spectroscopy measurements show that the activation energy of 0.341 eV can be considered as the emitting energy of hole from the ground state of the quantum dot. And the capacitance variation with temperature of the sample shows a platform at various frequencies with reverse bias 0.5 V, which indicates that the boundary of space charge region is located at the quantum dot layer where the large confined hole concentration blocks the further extension of space charge region. When the temperature increases from 120 K to 200 K, the holes in the dot emit out completely. The position of the platform shifting with the increase of the applied frequency shows the frequency effects of the charges in the quantum dot. The deep level transient spectroscopy results show that the charge concentration in the Ge quantum dot is a function of the pulse duration and the reverse bias voltage, the activation energy and capture cross-section of hole decrease with the increase of pulse duration due to the Coulomb charging effect. The valence-band offsets of hole in Ge dot obtained by admittance spectroscopy and deep level transient spectroscopy are 0.341 and 0.338 eV, respectively.

  4. Formation of microtubes from strained SiGe/Si heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Qin, H [Laboratory of Molecular-scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Shaji, N [Laboratory of Molecular-scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Merrill, N E [Laboratory of Molecular-scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Kim, H S [Laboratory of Molecular-scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Toonen, R C [Laboratory of Molecular-scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Blick, R H [Laboratory of Molecular-scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Roberts, M M [Department of Materials Science and Engineering, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, WI 53706 (United States); Savage, D E [Department of Materials Science and Engineering, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, WI 53706 (United States); Lagally, M G [Department of Materials Science and Engineering, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, WI 53706 (United States); Celler, G [SOITEC USA Inc., 2 Centennial Drive, Peabody, MA 01960 (United States)

    2005-11-15

    We report the formation of micrometre-sized SiGe/Si tubes by releasing strained SiGe/Si bilayers from substrates in a wet chemical-etching process. In order to explore statistical studies of dynamic formation of microtubes, we fabricated arrays of square bilayers. Due to the dynamic change in curvature of the bilayers, and hence the underlying etch channels, the etching process deviates from a transport-controlled regime to one of kinetic controlled. We identified two distinct modes of etching. A slow etching mode is associated with symmetric surface deformation in which the bilayers mostly retain their initial pattern. In the fast mode, bilayers are asymmetrically deformed while large etch channels are induced and etching becomes kinetically controlled. Etch rate dispersion is directly related to the degree of asymmetry in surface deformation. When the dimensions of the bilayers become significantly larger than the curvature radius, kinetic etching dominates. During the formation of tubes, SiGe/Si bilayers strongly interact with the liquid environment of etchant and solvent. Assisted by the surface tension of evaporating liquids, the tubes are drawn near the substrate and eventually fixed to it because of van der Waals forces. Our study illuminates the dynamic etching and curling processes involved with and provides insight on how a uniform etch rate and consistent curling directions can be maintained.

  5. Formation of microtubes from strained SiGe/Si heterostructures

    Science.gov (United States)

    Qin, H.; Shaji, N.; Merrill, N. E.; Kim, H. S.; Toonen, R. C.; Blick, R. H.; Roberts, M. M.; Savage, D. E.; Lagally, M. G.; Celler, G.

    2005-11-01

    We report the formation of micrometre-sized SiGe/Si tubes by releasing strained SiGe/Si bilayers from substrates in a wet chemical-etching process. In order to explore statistical studies of dynamic formation of microtubes, we fabricated arrays of square bilayers. Due to the dynamic change in curvature of the bilayers, and hence the underlying etch channels, the etching process deviates from a transport-controlled regime to one of kinetic controlled. We identified two distinct modes of etching. A slow etching mode is associated with symmetric surface deformation in which the bilayers mostly retain their initial pattern. In the fast mode, bilayers are asymmetrically deformed while large etch channels are induced and etching becomes kinetically controlled. Etch rate dispersion is directly related to the degree of asymmetry in surface deformation. When the dimensions of the bilayers become significantly larger than the curvature radius, kinetic etching dominates. During the formation of tubes, SiGe/Si bilayers strongly interact with the liquid environment of etchant and solvent. Assisted by the surface tension of evaporating liquids, the tubes are drawn near the substrate and eventually fixed to it because of van der Waals forces. Our study illuminates the dynamic etching and curling processes involved with and provides insight on how a uniform etch rate and consistent curling directions can be maintained.

  6. SiGe crystal growth aboard the international space station

    Science.gov (United States)

    Kinoshita, K.; Arai, Y.; Tsukada, T.; Inatomi, Y.; Miyata, H.; Tanaka, R.

    2015-05-01

    A silicon germanium mixed crystal Si1-xGex (x~0.5) 10 mm in diameter and 9.2 mm in length was grown by the traveling liquidus-zone (TLZ) method in microgravity by suppressing convection in a melt. Ge concentration of 49.8±2.5 at% has been established for the whole of the grown crystal. Compared with the former space experiment, concentration variation in the axial direction increased from ±1.5 at% to ±2.5 at% although average Ge concentration reached to nearly 50 at%. Excellent radial Ge compositional uniformity 52±0.5 at% was established in the region of 7-9 mm growth length, where axial compositional uniformity was also excellent. The single crystalline region is about 5 mm in length. The interface shape change from convex to concave is implied from both experimental results and numerical analysis. The possible cause of increase in concentration variation and interface shape change and its relation to the two-dimensional growth model are discussed.

  7. GaAs Photovoltaics on Polycrystalline Ge Substrates

    Science.gov (United States)

    Wilt, David M.; Pal, AnnaMaria T.; McNatt, Jeremiah S.; Wolford, David S.; Landis, Geoffrey A.; Smith, Mark A.; Scheiman, David; Jenkins, Phillip P.; McElroy Bruce

    2007-01-01

    High efficiency III-V multijunction solar cells deposited on metal foil or even polymer substrates can provide tremendous advantages in mass and stowage, particularly for planetary missions. As a first step towards that goal, poly-crystalline p/i/n GaAs solar cells are under development on polycrystalline Ge substrates. Organo Metallic Vapor Phase Epitaxy (OMVPE) parameters for pre-growth bake, nucleation and deposition have been examined. Single junction p/i/n GaAs photovoltaic devices, incorporating InGaP front and back window layers, have been grown and processed. Device performance has shown a dependence upon the thickness of a GaAs buffer layer deposited between the Ge substrate and the active device structure. A thick (2 m) GaAs buffer provides for both increased average device performance as well as reduced sensitivity to variations in grain size and orientation. Illumination under IR light (lambda > 1 micron), the cells showed a Voc, demonstrating the presence of an unintended photoactive junction at the GaAs/Ge interface. The presence of this junction limited the efficiency to approx.13% (estimated with an anti-refection coating) due to the current mismatch and lack of tunnel junction interconnect.

  8. Nonlinear characterization of GeSbS chalcogenide glass waveguides

    Science.gov (United States)

    Choi, Ju Won; Han, Zhaohong; Sohn, Byoung-Uk; Chen, George F. R.; Smith, Charmayne; Kimerling, Lionel C.; Richardson, Kathleen A.; Agarwal, Anuradha M.; Tan, Dawn T. H.

    2016-12-01

    GeSbS ridge waveguides have recently been demonstrated as a promising mid – infrared platform for integrated waveguide – based chemical sensing and photodetection. To date, their nonlinear optical properties remain relatively unexplored. In this paper, we characterize the nonlinear optical properties of GeSbS glasses, and show negligible nonlinear losses at 1.55 μm. Using self – phase modulation experiments, we characterize a waveguide nonlinear parameter of 7 W‑1/m and nonlinear refractive index of 3.71 × 10‑18 m2/W. GeSbS waveguides are used to generate supercontinuum from 1280 nm to 2120 nm at the ‑30 dB level. The spectrum expands along the red shifted side of the spectrum faster than on the blue shifted side, facilitated by cascaded stimulated Raman scattering arising from the large Raman gain of chalcogenides. Fourier transform infrared spectroscopic measurements show that these glasses are optically transparent up to 25 μm, making them useful for short – wave to long – wave infrared applications in both linear and nonlinear optics.

  9. Structural origin of resistance drift in amorphous GeTe

    Science.gov (United States)

    Zipoli, Federico; Krebs, Daniel; Curioni, Alessandro

    2016-03-01

    We used atomistic simulations to study the origin of the change of resistance over time in the amorphous phase of GeTe, a prototypical phase-change material (PCM). Understanding the cause of resistance drift is one of the biggest challenges to improve multilevel storage technology. For this purpose, we generated amorphous structures via classical molecular-dynamics simulations under conditions as close as possible to the experimental operating ones of such memory devices. Moreover, we used the replica-exchange technique to generate structures comparable with those obtained in the experiment after long annealing that show an increase of resistance. This framework allowed us to overcome the main limitation of previous simulations, based on density-functional theory, that suffered from being computationally too expensive therefore limited to the nanosecond time scale. We found that resistance drift is caused by consumption of Ge atom clusters in which the coordination of at least one Ge atom differs from that of the crystalline phase and by removal of stretched bonds in the amorphous network, leading to a shift of the Fermi level towards the middle of the band gap. These results show that one route to design better memory devices based on current chalcogenide alloys is to reduce the resistance drift by increasing the rigidity of the amorphous network.

  10. Surfactant mediated slurry formulations for Ge CMP applications

    KAUST Repository

    Basim, G. Bahar

    2013-01-01

    In this study, slurry formulations in the presence of self-assembled surfactant structures were investigated for Ge/SiO2 CMP applications in the absence and presence of oxidizers. Both anionic (sodium dodecyl sulfate-SDS) and cationic (cetyl trimethyl ammonium bromide-C12TAB) micelles were used in the slurry formulations as a function of pH and oxidizer concentration. CMP performances of Ge and SiO2 wafers were evaluated in terms of material removal rates, selectivity and surface quality. The material removal rate responses were also assessed through AFM wear rate tests to obtain a faster response for preliminary analyses. The surfactant adsorption characteristics were studied through surface wettability responses of the Ge and SiO2 wafers through contact angle measurements. It was observed that the self-assembled surfactant structures can help obtain selectivity on the silica/germanium system at low concentrations of the oxidizer in the slurry. © 2013 Materials Research Society.

  11. Photoluminescence enhancement in double Ge/Si quantum dot structures

    Science.gov (United States)

    Zinovieva, A. F.; Zinovyev, V. A.; Nikiforov, A. I.; Timofeev, V. A.; Mudryi, A. V.; Nenashev, A. V.; Dvurechenskii, A. V.

    2016-12-01

    Luminescence properties of double Ge/Si quantum dot structures were studied at liquid helium temperature depending on the Si spacer thickness d in QD molecules. A seven-fold increase of the integrated photoluminescence intensity was obtained for the structures with optimal thickness d = 2 nm. This enhancement is explained by increasing the overlap integral of electron and hole wave functions. Two main factors promote this increasing. The first one is that the electrons are localized at the QD base edges and their wave functions are the linear combinations of the states of in-plane Δ valleys, which are perpendicular in k-space to the growth direction [001]. This results in the increasing probability of electron penetration into Ge barriers. The second factor is the arrangement of Ge nanoclusters in closely spaced QD groups. The strong tunnel coupling of QDs within these groups increases the probability of hole finding at the QD base edge, that also promotes the increase of the radiative recombination probability.

  12. Donors in Ge as qubits —Establishing physical attributes

    Science.gov (United States)

    Baena, A.; Saraiva, A. L.; Menezes, Marcos G.; Koiller, Belita

    2016-10-01

    Quantum electronic devices at the single-impurity level demand the understanding of the physical attributes of dopants with an unprecedented accuracy. Germanium-based technologies have been developed recently, creating the necessity to adapt the latest theoretical tools to the unique electronic structure of this material. We investigate basic properties of donors in Ge which are not known experimentally, but are indispensable for qubit implementations. Our approach provides a description of the wave function at multiscale, associating microscopic information from density functional theory and envelope functions from state-of-the-art multivalley effective mass calculations, including a central-cell correction designed to reproduce the energetics of all group-V donor species (P, As, Sb and Bi). With this formalism, we predict the binding energies of negatively ionized donors (D- state). Furthermore, we investigate the signatures of buried donors to be expected from scanning tunneling microscopy (STM). The naive assumption that attributes of donor electrons in other semiconductors may be extrapolated to Ge is shown to fail, similarly to earlier attempts to recreate in Si qubits designed for GaAs. Our results suggest that the mature techniques available for qubit realizations may be adapted to germanium to some extent, but the peculiarities of the Ge band structure will demand new ideas for fabrication and control.

  13. From X-Rays to MRI: Physics in GE

    Science.gov (United States)

    Schmitt, Roland W.

    2004-03-01

    The GE Research Laboratory, founded in 1900, became the first laboratory of scientific research in U.S. industry. William Coolidge, a physicist, joined the laboratory in 1905 and produced two advances of immense importance. The first, ductile tungsten, is still the heart of every incandescent light bulb. The second, the "Coolidge" X-Ray tube, remains an essential tool of modern medicine. In the process, Coolidge explored two main approaches of physics in industry. One addresses a commercial problem or opportunity (better light bulbs) and finds interesting physics. The other explores interesting physics (X-rays) and creates a commercial opportunity. This paper addresses the mix of these approaches during GE's years as an "electric" (and therefore physics-based) company. Episodes include the following: the work of Irving Langmuir (1932 Nobel laureate in chemistry, but as much physicist as chemist); the post-World War II "golden age of industrial physics" when the endless frontier offered opportunities from nuclear power to diamond making to superconductivity; the Nobel-prize winning work of Ivar Giaever; and interdisciplinary efforts that enabled GE to become a world business leader in two medical diagnostic technologies it did not invent: computed tomography and magnetic resonance imaging. I will speculate on whether this mix of problem-driven and opportunity-driven effort is as relevant to the 21st century as it was to the 20th.

  14. A broad 750 GeV diphoton resonance? Not alone

    CERN Document Server

    Roig, P

    2016-01-01

    The existence of a possible resonance in the diphoton channel with mass of 750 GeV is still under study and will be hopefully clarified this summer. If confirmed with a large width, it will be difficult to accommodate within weakly interacting beyond Standard Model theories, hinting a composite scenario. By means of forward sum-rules for $\\gamma\\gamma$ and $gg$ scattering we show that a spin-0 resonance with mass of the order of the TeV and a sizable $\\gamma\\gamma$ or $gg$ partial width -of the order of a few GeV- must be accompanied by higher spin resonances with $J_R\\geq 2$ with similar properties, as expected in strongly coupled extensions of the Standard Model or, alternatively, in higher dimensional deconstructed duals. Furthermore, independently of whether the 750 GeV candidate is a scalar or a tensor, the large contribution to the forward sum-rules in the referred scenario implies the presence of states in the spectrum with $J_R\\geq 2$, being these high spin particles a manifestation of new extra-dimen...

  15. Nondiffusive lattice thermal transport in Si-Ge alloy nanowires

    Science.gov (United States)

    Upadhyaya, M.; Aksamija, Z.

    2016-11-01

    We present a calculation of the lattice thermal conductivity of Si-Ge nanowires (NWs), based on solving the Boltzmann transport equation by the Monte Carlo method of sampling the phonon mean free paths. We augment the previous work with the full phonon dispersion and a partially diffuse momentum-dependent specularity model for boundary roughness scattering. We find that phonon flights are comprised of a mix of long free flights over several μ m interrupted by bursts of short flights, resulting in a heavy-tailed distribution of flight lengths, typically encountered in Lévy walk dynamics. Consequently, phonon transport in Si-Ge NWs is neither entirely ballistic nor diffusive; instead, it falls into an intermediate regime called superdiffusion where thermal conductivity scales with the length of the NW as κ ∝Lα with the exponent of length dependence α ≈0.33 over a broad range of wire lengths 10 nm thermal conductivity in Si-Ge alloy NWs is length dependent up to 10 μ m and therefore can be tuned for thermoelectric applications.

  16. Electronic properties of Fibonacci and random Si-Ge chains

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, M S [Escola de Ciencias e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil); Azevedo, David L; Hadad, A [Departamento de Fisica, Universidade Federal do Maranhao 65080-040, Sao LuIs-MA (Brazil); Galvao, D S, E-mail: mvasconcelos@ect.ufrn.br [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas CP 6165, 13083-970 Campinas, SP (Brazil)

    2011-10-12

    In this paper we address a theoretical calculation of the electronic spectra of an Si-Ge atomic chain that is arranged in a Fibonacci quasi-periodic sequence, by using a semi-empirical quantum method based on the Hueckel extended model. We apply the Fibonacci substitutional sequences in the atomic building blocks A(Si) and B(Ge) through the inflation rule or a recursion relation. In our ab initio calculations we use only a single point, which is sufficient for considering all the orbitals and charge distribution across the entire system. Although the calculations presented here are more complete than the models adopted in the literature which take into account the electronic interaction only up to the second and third neighbors, an interesting property remains in their electronic spectra: the fractality (which is the main signature of this kind of system). We discuss this fractality of the spectra and we compare them with the random arrangement of the Si-Ge atomic chain, and with previous results based on the tight-binding approximation of the Schroedinger equation considering up to the nearest neighbor. (paper)

  17. Electronic properties of Fibonacci and random Si-Ge chains.

    Science.gov (United States)

    Vasconcelos, M S; Azevedo, David L; Hadad, A; Galvão, D S

    2011-10-12

    In this paper we address a theoretical calculation of the electronic spectra of an Si-Ge atomic chain that is arranged in a Fibonacci quasi-periodic sequence, by using a semi-empirical quantum method based on the Hückel extended model. We apply the Fibonacci substitutional sequences in the atomic building blocks A(Si) and B(Ge) through the inflation rule or a recursion relation. In our ab initio calculations we use only a single point, which is sufficient for considering all the orbitals and charge distribution across the entire system. Although the calculations presented here are more complete than the models adopted in the literature which take into account the electronic interaction only up to the second and third neighbors, an interesting property remains in their electronic spectra: the fractality (which is the main signature of this kind of system). We discuss this fractality of the spectra and we compare them with the random arrangement of the Si-Ge atomic chain, and with previous results based on the tight-binding approximation of the Schrödinger equation considering up to the nearest neighbor.

  18. In-situ Ga doping of fully strained Ge{sub 1-x}Sn{sub x} heteroepitaxial layers grown on Ge(001) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Shimura, Y., E-mail: ysimura@alice.xtal.nagoya-u.ac.jp [Graduate School of Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan); Research Fellow of the Japan Society for the Promotion of Science (Japan); Takeuchi, S.; Nakatsuka, O. [Graduate School of Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan); Vincent, B.; Gencarelli, F.; Clarysse, T.; Vandervorst, W.; Caymax, M.; Loo, R. [imec, Kapeldreef 75, B-3001 Leuven (Belgium); Jensen, A. [CAPRES A/S, Scion-DTU, Building 373, DK-2800, Kgs. Lyngby (Denmark); Petersen, D.H. [Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345B, DK-2800 Kgs. Lyngby (Denmark); Zaima, S. [Graduate School of Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan)

    2012-02-01

    We have investigated the Ga and Sn content dependence of the crystallinity and electrical properties of Ga-doped Ge{sub 1-x}Sn{sub x} layers that are heteroepitaxially grown on Ge(001) substrates. The doping of Ga to levels as high as the solubility limit of Ga at the growth temperature leads to the introduction of dislocations, due to the increase in the strain of the Ge{sub 1-x}Sn{sub x} layers. We achieved the growth of a fully strained Ge{sub 0.922}Sn{sub 0.078} layer on Ge with a Ga concentration of 5.5 Multiplication-Sign 10{sup 19} /cm{sup 3} without any dislocations and stacking faults. The resistivity of the Ga-doped Ge{sub 1-x}Sn{sub x} layer decreased as the Sn content was increased. This decrease was due to an increase in the carrier concentration, with an increase in the activation level of Ga atoms in the Ge{sub 1-x}Sn{sub x} epitaxial layers being induced by the introduction of Sn. As a result, we found that the resistivity for the Ge{sub 0.950}Sn{sub 0.050} layer annealed at 600 Degree-Sign C for 1 min is 3.6 times less than that of the Ga-doped Ge/Ge sample. - Highlights: Black-Right-Pointing-Pointer Heavy Ga-doping into fully strained GeSn layers without the introduction of dislocations Black-Right-Pointing-Pointer The uniform Ga depth profile allowed the introduction of Sn Black-Right-Pointing-Pointer The decrease in resistivity with an increase in the activation level of Ga was caused by the introduction of Sn.

  19. Potential of asymmetrical Si/Ge and Ge/Si based hetero-junction transit time devices over homo-junction counterparts for generation of high power

    Institute of Scientific and Technical Information of China (English)

    Moumita Mukherjee; Pravash R. Tripathy; S. P. Pati

    2011-01-01

    Static and dynamic properties of both complementary n-Ge/p-Si and p-Ge/n-Si hetero-junction DoubleDrift IMPATT diodes have been investigated by an advanced and realistic computer simulation technique,developed by the authors,for operation in the Ka-,V- and W-band frequencies.The results are further compared with corresponding Si and Ge homo-junction devices.The study shows high values of device efficiency,such as 23%,22% and 21.5%,for n-Ge/p-Si IMPATTs at the Ka,V and W bands,respectively.The peak device negative conductances for n-Si/p-Ge and n-Ge/p-Si hetero-junction devices found to be 50.7 × 106 S/m2 and 71.3 × 106 S/m2,which are ~3-4 times better than their Si and Ge counterparts at the V-band.The computed values of RF powerdensity for n-Ge/p-Si hetero-junction IMPATTs are 1.0 × 109,1.1 × 109 and 1.4 × 109 W/m2,respectively,for Ka-,V- and W-band operation,which can be observed to be the highest when compared with Si,Ge and n-Si/p-Ge devices.Both of the hetero-junctions,especially the n-Ge/p-Si hetero-junction diode,can thus become a superior RF-power generator over a wide range of frequencies.The present study will help the device engineers to choose a suitable material pair for the development of high-power MM-wave IMPATT for applications in the civil and defense-related arena.

  20. Search for supersymmetric particles at 130 GeV < √s < 140 GeV at LEP

    Science.gov (United States)

    Acciarri, M.; Adam, A.; Adriani, O.; Aguilar-Benitez, M.; Ahlen, S.; Alpat, B.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alverson, G.; Alviggi, M. G.; Ambrosi, G.; Anderhub, H.; Andreev, V. P.; Angelescu, T.; Antreasyan, D.; Arefiev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Baksay, L.; Ball, R. C.; Banerjee, S.; Banicz, K.; Barillère, R.; Barone, L.; Bartalini, P.; Baschirotto, A.; Basile, M.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B. L.; Biasini, M.; Biland, A.; Bilei, G. M.; Blaising, J. J.; Blyth, S. C.; Bobbink, G. J.; Bock, R.; Böhm, A.; Borgia, B.; Boucham, A.; Bourilkov, D.; Bourquin, M.; Brambilla, E.; Branson, J. G.; Brigljevic, V.; Brock, I. C.; Buijs, A.; Bujak, A.; Burger, J. D.; Burger, W. J.; Busenitz, J.; Buytenhuijs, A.; Cai, X. D.; Campanelli, M.; Capell, M.; Romeo, G. Cara; Caria, M.; Carlino, G.; Cartacci, A. M.; Casaus, J.; Castellini, G.; Castello, R.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Cesaroni, F.; Chamizo, M.; Chan, A.; Chang, Y. H.; Chaturvedi, U. K.; Chemarin, M.; Chen, A.; Chen, C.; Chen, G.; Chen, G. M.; Chen, H. F.; Chen, H. S.; Chereau, X.; Chiefari, G.; Chien, C. Y.; Choi, M. T.; Cifarelli, L.; Cindolo, F.; Civinini, C.; Clare, I.; Clare, R.; Cohn, H. O.; Coignet, G.; Colijn, A. P.; Colino, N.; Commichau, V.; Costantini, S.; Cotorobai, F.; de la Cruz, B.; Dai, T. S.; D'Alessandro, R.; de Asmundis, R.; De Boeck, H.; Degré, A.; Deiters, K.; Denes, P.; DeNotaristefani, F.; DiBitonto, D.; Diemoz, M.; van Dierendonck, D.; Di Lodovico, F.; Dionisi, C.; Dittmar, M.; Dominguez, A.; Doria, A.; Dorne, I.; Dova, M. T.; Drago, E.; Duchesneau, D.; Duinker, P.; Duran, I.; Dutta, S.; Easo, S.; Efremenko, Yu; El Mamouni, H.; Engler, A.; Eppling, F. J.; Erné, F. C.; Ernenwein, J. P.; Extermann, P.; Fabre, M.; Faccini, R.; Falciano, S.; Favara, A.; Fay, J.; Felcini, M.; Ferguson, T.; Fernandez, D.; Ferroni, F.; Fesefeldt, H.; Fiandrini, E.; Field, J. H.; Filthaut, F.; Fisher, P. H.; Forconi, G.; Fredj, L.; Freudenreich, K.; Galaktionov, Yu; Ganguli, S. N.; Gau, S. S.; Gentile, S.; Gerald, J.; Gheordanescu, N.; Giagu, S.; Goldfarb, S.; Goldstein, J.; Gong, Z. F.; Gougas, A.; Gratta, G.; Gruenewald, M. W.; Gupta, V. K.; Gurtu, A.; Gutay, L. J.; Hangarter, K.; Hartmann, B.; Hasan, A.; He, J. T.; Hebbeker, T.; Hervé, A.; van Hoek, W. C.; Hofer, H.; Hoorani, H.; Hou, S. R.; Hu, G.; Ilyas, M. M.; Innocente, V.; Janssen, H.; Jin, B. N.; Jones, L. W.; de Jong, P.; Josa-Mutuberria, I.; Kasser, A.; Khan, R. A.; Kamyshkov, Yu; Kapinos, P.; Kapustinsky, J. S.; Karyotakis, Y.; Kaur, M.; Kienzle-Focacci, M. N.; Kim, D.; Kim, J. K.; Kim, S. C.; Kim, Y. G.; Kinnison, W. W.; Kirkby, A.; Kirkby, D.; Kirkby, J.; Kittel, W.; Klimentov, A.; König, A. C.; Köngeter, A.; Korolko, I.; Koutsenko, V.; Koulbardis, A.; Kraemer, R. W.; Kramer, T.; Krenz, W.; Kuijten, H.; Kunin, A.; de Guevara, P. Ladron; Landi, G.; Lapoint, C.; Lassila-Perini, K.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Lee, J. S.; Lee, K. Y.; Le Goff, J. M.; Leiste, R.; Lenti, M.; Leonardi, E.; Levtchenko, P.; Li, C.; Lieb, E.; Lin, W. T.; Linde, F. L.; Lindemann, B.; Lista, L.; Liu, Z. A.; Lohmann, W.; Longo, E.; Lu, W.; Lu, Y. S.; Lübelsmeyer, K.; Luci, C.; Luckey, D.; Ludovici, L.; Luminari, L.; Lustermann, W.; Ma, W. G.; Macchiolo, A.; Maity, M.; Majumder, G.; Malgeri, L.; Malinin, A.; Maña, C.; Mangla, S.; Marchesini, P.; Marin, A.; Martin, J. P.; Marzano, F.; Massaro, G. G. G.; Mazumdar, K.; McNally, D.; McNeil, R. R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W. J.; von der Mey, M.; Mi, Y.; Mihul, A.; van Mil, A. J. W.; Mirabelli, G.; Mnich, J.; Möller, M.; Monteleoni, B.; Moore, R.; Morganti, S.; Mount, R.; Müller, S.; Muheim, F.; Nagy, E.; Nahn, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nippe, A.; Nowak, H.; Organtini, G.; Ostonen, R.; Pandoulas, D.; Paoletti, S.; Paolucci, P.; Park, H. K.; Pascale, G.; Passaleva, G.; Patricelli, S.; Paul, T.; Pauluzzi, M.; Paus, C.; Pauss, F.; Peach, D.; Pei, Y. J.; Pensotti, S.; Perret-Gallix, D.; Petrak, S.; Pevsner, A.; Piccolo, D.; Pieri, M.; Pinto, J. C.; Piroué, P. A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Postema, H.; Produit, N.; Raghavan, R.; Rahal-Callot, G.; Rancoita, P. G.; Rattaggi, M.; Raven, G.; Razis, P.; Read, K.; Redaelli, M.; Ren, D.; Rescigno, M.; Reucroft, S.; Ricker, A.; Riemann, S.; Riemers, B. C.; Riles, K.; Ro, S.; Robohm, A.; Rodin, J.; Rodriguez, F. J.; Roe, B. P.; Röhner, S.; Romero, L.; Rosier-Lees, S.; Rosselet, Ph; van Rossum, W.; Roth, S.; Rubio, J. A.; Rykaczewski, H.; Salicio, J.; Sanchez, E.; Santocchia, A.; Sarakinos, M. E.; Sarkar, S.; Sassowsky, M.; Schäfer, C.; Schegelsky, V.; Schmidt-Kaerst, S.; Schmitz, D.; Schmitz, P.; Schneegans, M.; Schoeneich, B.; Scholz, N.; Schopper, H.; Schotanus, D. J.; Schulte, R.; Schultze, K.; Schwenke, J.; Schwering, G.; Sciacca, C.; Sciarrino, D.; Sens, J. C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shukla, J.; Shumilov, E.; Siedenburg, T.; Son, D.; Sopczak, A.; Smith, B.; Spillantini, P.; Steuer, M.; Stickland, D. P.; Sticozzi, F.; Stone, H.; Stoyanov, B.; Straessner, A.; Strauch, K.; Sudhakar, K.; Sultanov, G.; Sun, L. Z.; Susinno, G. F.; Suter, H.; Swain, J. D.; Tang, X. W.; Tauscher, L.; Taylor, L.; Ting, Samuel C. C.; Ting, S. M.; Toker, O.; Tonisch, F.; Tonutti, M.; Tonwar, S. C.; Tóth, J.; Tsaregorodtsev, A.; Tully, C.; Tuchscherer, H.; Tung, K. L.; Ulbricht, J.; Uwer, U.; Valente, E.; Van de Walle, R. T.; Vetlitsky, I.; Viertel, G.; Vivargent, M.; Völkert, R.; Vogel, H.; Vogt, H.; Vorobiev, I.; Vorobyov, A. A.; Vorobyov, An. A.; Vorvolakos, A.; Wadhwa, M.; Wallraff, W.; Wang, J. C.; Wang, X. L.; Wang, Y. F.; Wang, Z. M.; Weber, A.; Wittgenstein, F.; Wu, S. X.; Wynhoff, S.; Xu, J.; Xu, Z. Z.; Yang, B. Z.; Yang, C. G.; Yao, X. Y.; Ye, J. B.; Yeh, S. C.; You, J. M.; Zaccardelli, C.; Zalite, An; Zemp, P.; Zeng, J. Y.; Zeng, Y.; Zhang, Z.; Zhang, Z. P.; Zhou, B.; Zhou, G. J.; Zhou, Y.; Zhu, G. Y.; Zhu, R. Y.; Zichichi, A.; L3 Collaboration

    1996-02-01

    A search for supersymmetric particles (charginos, neutralinos, sleptons and stop quarks) has been performed with data collected by the L3 detector during the November 1995 run of the LEP collider at centre of mass energies between 130 and 140 GeV with a total integrated luminosity of 5.1 pb -1. We observe no signal for supersymmetric particles and we set improved exclusion limits on their production cross sections and masses.

  1. Multiple collision effects on the antiproton production by high energy proton (100 GeV - 1000 GeV)

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hiroshi; Powell, J.

    1987-01-01

    Antiproton production rates which take into account multiple collision are calculated using a simple model. Methods to reduce capture of the produced antiprotons by the target are discussed, including geometry of target and the use of a high intensity laser. Antiproton production increases substantially above 150 GeV proton incident energy. The yield increases almost linearly with incident energy, alleviating space charge problems in the high current accelerator that produces large amounts of antiprotons.

  2. Influence of hydrogen surface passivation on Sn segregation, aggregation, and distribution in GeSn/Ge(001) materials

    Science.gov (United States)

    Johll, Harman; Samuel, Milla; Koo, Ruey Yi; Kang, Hway Chuan; Yeo, Yee-Chia; Tok, Eng Soon

    2015-05-01

    Plane-wave density functional theory is used to investigate the impact of hydrogen passivation of the p(2×2) reconstructed Ge1-xSnx surface on Sn segregation, aggregation, and distribution. On a clean surface, Sn preferentially segregates to the surface layer, with surface coverages of 25%, 50%, and 100% for total Sn concentrations of 2.5%, 5.0%, and 10.0%, respectively. In contrast, a hydrogen passivated surface increases interlayer migration of Sn to subsurface layers, in particular, to the third layer from the surface, and results in surface coverages of 0%, 0%, and 50% corresponding to Sn concentrations of 2.5%, 5.0%, and 10.0%, respectively. Hydrogen transfer from a Ge-capped surface to the one enriched with increasing Sn surface coverage is also an unfavorable process. The presence of hydrogen therefore reduces the surface energy by passivating the reactive dangling bonds and enhancing Sn interlayer migration to the subsurface layers. For both clean and hydrogenated surfaces, aggregation of Sn at the surface layer is also not favored. We explain these results by considering bond enthalpies and the enthalpies of hydrogenation for various surface reactions. Our results thus point to reduced Sn segregation to the surface in a Ge1-xSnx epitaxial thin film if CVD growth, using hydride precursors in the hydrogen limited growth regime, is used. This would lead to a more abrupt interface and is consistent with recent experimental observation. Hydrogenation is therefore a promising method for controlling and manipulating elemental population of Sn in a Ge1-xSnx epitaxial thin film.

  3. Te-rich Ge-Te-Se glass for the CO2 infrared detection at 15 μm

    NARCIS (Netherlands)

    Maurugeon, S.; Bureau, B.; Boussard-Plédel, C.; Faber, A.J.; Zhang, X.H.; Geliesen, W.; Lucas, J.H.

    2009-01-01

    Te80-xGe20Sex glasses have been prepared along the GeSe4-GeTe4 axis using the classical method in silica tube under vacuum. A phase separation domain appears for composition around Te40Ge20Se40. Our attention was turned toward the Te-rich compositions corresponding to 1 < x < 5 at.%. These glasses a

  4. Si基Ge/SiGeⅠ型量子阱结构的理论设计和实验研究%Design and experiment of Si-based Ge/SiGe type-Ⅰ quantum well structure

    Institute of Scientific and Technical Information of China (English)

    陈城钊; 陈阳华; 黄诗浩; 李成; 赖虹凯; 陈松岩

    2012-01-01

    Si-based Ge/SiGe type-Ⅰ quantum well is theoretically designed based on the energy band engineering theory.High-quality Ge/ SiGe multiple quantum wells were grown on Si-based germanium virtual substrates by ultra-high vacuum chemical vapor deposition.When the thickness of the Ge quantum well is reduced from 15 nm to 12 nm and 11 nm,the quantum confinement effect in the Ge/SiGe quantum wells can be directly demonstrated by room temperature photoluminescence(PL),which is in good agreement with the theoretical prediction.But when the thickness of the Ge quantum well is gradually reduced to 9 nm and 7 nm,the experimental result doesn′t obey the theoretical prediction.Further experiments reveal the reason that when the thickness of the Ge quantum well is reduced to some extent,the photoluminescence from the direct band transition of the Ge well will be restrained and it mainly originates from the Ge virtual substrate.%基于能带工程理论,设计了Si基Ge/SiGeⅠ型量子阱结构。采用超高真空化学气相淀积系统,制备出高质量的Si基Ge/SiGe多量子阱系列材料。当样品中Ge量子阱宽从15nm减少到12nm和11nm时,室温下荧光(PL)光谱观测到量子限制效应引起的直接带跃迁发光峰位的蓝移,峰位的实验值与理论值符合得很好;当Ge量子阱宽逐渐减小到9nm和7nm时,测试得到样品的PL谱峰位却与理论预期出现了较大的差值。进一步的实验表明,这主要是由于量子阱厚度小到一定程度时,量子阱的直接带发光受到抑制,其发光主要源于Ge虚拟衬底。

  5. Giant piezoelectricity of monolayer group IV monochalcogenides: SnSe, SnS, GeSe, and GeS

    Energy Technology Data Exchange (ETDEWEB)

    Fei, Ruixiang; Yang, Li, E-mail: lyang@physics.wustl.edu [Department of Physics, Washington University, St. Louis, Missouri 63130 (United States); Li, Wenbin [Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Li, Ju [Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-10-26

    We predict enormous, anisotropic piezoelectric effects in intrinsic monolayer group IV monochalcogenides (MX, M=Sn or Ge, X=Se or S), including SnSe, SnS, GeSe, and GeS. Using first-principle simulations based on the modern theory of polarization, we find that their piezoelectric coefficients are about one to two orders of magnitude larger than those of other 2D materials, such as MoS{sub 2} and GaSe, and bulk quartz and AlN which are widely used in industry. This enhancement is a result of the unique “puckered” C{sub 2v} symmetry and electronic structure of monolayer group IV monochalcogenides. Given the achieved experimental advances in the fabrication of monolayers, their flexible character, and ability to withstand enormous strain, these 2D structures with giant piezoelectric effects may be promising for a broad range of applications such as nano-sized sensors, piezotronics, and energy harvesting in portable electronic devices.

  6. Synthesis, crystal structure and properties of [(dien)2Mn]Ge2S4 with mixed-valent Ge centers

    Science.gov (United States)

    Yue, Cheng-Yang; Yuan, Zhuang-Dong; Zhang, Lu-Ge; Wang, Ya-Bai; Liu, Guo-Dong; Gong, Liao-Kuo; Lei, Xiao-Wu

    2013-10-01

    One new manganese thiogermanate, [(dien)2Mn]Ge2S4 (dien=diethylenetriamine), was prepared under mild solvothermal conditions and structurally and spectroscopically characterized. The title compound crystallizes in the orthorhombic system, chiral space group P212121 (no. 19) with a=9.113(4) Å, b=12.475(5) Å, c=17.077(7) Å, V=1941.5(15) Å3 and Z=4. Its structure features a three-dimensional (3D) network composed of a one-dimensional (1D) [Ge2S4]2- anionic chain and a [(dien)2Mn]2+ complex interconnected via various hydrogen bonds. The most interesting structural feature of the compound is the presence of two different oxidation states of germanium centers in the 1D [Ge2S4]2- chain, which is also supported by the result of X-ray photoelectron spectroscopy measurement. The optical property of the title compound has also been studied by UV-vis spectra.

  7. Exploring hadron structure through exclusive kaon electroproduction from JLab 6GeV to 12GeV

    Science.gov (United States)

    Carmignotto, Marco; Horn, Tanja; Sapkota, Indra; Mkrtchyan, Arthur

    2015-10-01

    Exclusive reactions have been successfully used to probe hadrons at long and short distance scales, allowing us to study the interaction of elementary particles and their dynamics on the basis of Quantum Chromodynamics (QCD). The electroproduction of mesons has shown to be a powerful tool for these studies. High precision data for the pion taken at the 6 GeV Jefferson Lab provided important information about the pion form factor and brought us puzzles regarding the applicability of hard-soft QCD factorization. The kaon provides an interesting way to expand these studies, opening the possibility to access the production mechanism involving strangeness physics and also search for the onset of factorization on systems containing heavier quarks. Most of the precision cross section measurements at the 6 GeV Jefferson Lab were primarily designed for pions, but some of these experiments also captured kaons in their acceptance. In this talk, I will show preliminary kaon cross section results from such experiments. I will also discuss plans to explore the extended Q2 range capability with dedicated kaon experiments at the 12 GeV Jefferson Lab to study the onset of factorization for mesons including strangeness and the meson electroproduction mechanism in general. JSA Graduate Fellowship.

  8. Templated self-assembly of SiGe quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Dais, Christian

    2009-08-19

    This PhD thesis reports on the fabrication and characterization of exact aligned SiGe quantum dot structures. In general, SiGe quantum dots which nucleate via the Stranski-Krastanov growth mode exhibit broad size dispersion and nucleate randomly on the surface. However, to tap the full potential of SiGe quantum dots it is necessary to control the positioning and size of the dots on a nanometer length, e.g. for electronically addressing of individual dots. This can be realized by so-called templated self-assembly, which combines top-down lithography with bottom-up selfassembly. In this process the lithographically defined pits serve as pre-defined nucleation points for the epitaxially grown quantum dots. In this thesis, extreme ultraviolet interference lithography at a wavelength of e=13.4 nm is employed for prepatterning of the Si substrates. This technique allows the precise and fast fabrication of high-resolution templates with a high degree of reproducibility. The subsequent epitaxial deposition is either performed by molecular beam epitaxy or low-pressure chemical vapour deposition. It is shown that the dot nucleation on pre-patterned substrates depends strongly on the lithography parameters, e.g. size and periodicity of the pits, as well as on the epitaxy parameters, e.g. growth temperature or material coverage. The interrelations are carefully analyzed by means of scanning force microscopy, transmission electron microscopy and X-ray diffraction measurements. Provided that correct template and overgrowth parameters are chosen, perfectly aligned and uniform SiGe quantum dot arrays of different period, size as well as symmetry are created. In particular, the quantum dot arrays with the so far smallest period (35 nm) and smallest size dispersion are fabricated in this thesis. Furthermore, the strain fields of the underlying quantum dots allow the fabrication of vertically aligned quantum dot stacks. Combining lateral and vertical dot alignment results in three

  9. Electron and hole separation in Ge nanocones formed on Si{sub 1−x}Ge{sub x} solid solution by Nd:YAG laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Gorb, A., E-mail: g_alla@ukr.net [Department of Physics, Taras Shevchenko Kyiv National University, Kyiv 01601 (Ukraine); Korotchenkov, O.; Kuryliuk, V. [Department of Physics, Taras Shevchenko Kyiv National University, Kyiv 01601 (Ukraine); Medvid, A.; Mozolevskis, G. [Research Laboratory of Semiconductor Physics, Institute of Technical Physics, Riga Technical University, 14/24 Azenes Str., Riga, LV-1048 (Latvia); Nadtochiy, A.; Podolian, A. [Department of Physics, Taras Shevchenko Kyiv National University, Kyiv 01601 (Ukraine)

    2015-08-15

    Highlights: • Nd:YAG laser radiation forms Ge nanocones on the Si{sub 1−x}Ge{sub x} surface. • The laser irradiation significantly increases the surface photovoltage signal. • Technique provides carrier separation pathways without deteriorating the surface quality. • Technique is advantageous for developing photodetector and the light source devices. - Abstract: The photoelectric characteristics of Ge nanocone structures, which are formed on Si surfaces by Nd:YAG laser radiation, is reported. It is found that exposing the SiGe/Si structure to irradiation intensities as high as 1.0 MW/cm{sup 2} Nd:YAG laser base frequency, which corresponds to effective formation of Ge nanocones on SiGe solid solution, significantly increases the surface photovoltage signal. The photovoltage decays do not shorten significantly with irradiation, thus indicating the fact that laser irradiation technique used here is capable of preventing the generation of considerable amount of carrier traps and recombination centers in the SiGe/Si structure and nanocones. From photovoltaic evidence it is therefore inferred that the laser irradiation fabrication technique is capable of providing well-defined carrier separation pathways without deteriorating the quality of the SiGe/Si structure and nanocones. Therefore, this technique can provide a cost-effective means for producing more effective photodetection devices in the near infrared.

  10. Large-angle production of charged pions by 3 GeV/c - 12.9 GeV/c protons on beryllium, aluminium and lead targets

    CERN Document Server

    Catanesi, M.G.; Edgecock, R.; Ellis, Malcolm; Soler, F.J.P.; Gossling, C.; Bunyatov, S.; Krasnoperov, A.; Popov, B.; Serdiouk, V.; Tereschenko, V.; Di Capua, E.; Vidal-Sitjes, G.; Artamonov, A.; Giani, S.; Gilardoni, S.; Gorbunov, P.; Grant, A.; Grossheim, A.; Ivanchenko, V.; Kayis-Topaksu, A.; Panman, J.; Papadopoulos, I.; Tcherniaev, E.; Tsukerman, I.; Veenhof, R.; Wiebusch, C.; Zucchelli, P.; Blondel, A.; Borghi, S.; Morone, M.C.; Prior, G.; Schroeter, R.; Meurer, C.; Gastaldi, U.; Mills, G.B.; Graulich, J.S.; Gregoire, G.; Bonesini, M.; Ferri, F.; Kirsanov, M.; Bagulya, A.; Grichine, V.; Polukhina, N.; Palladino, V.; Coney, L.; Schmitz, D.; Barr, G.; De Santo, A.; Bobisut, F.; Gibin, D.; Guglielmi, A.; Mezzetto, M.; Dumarchez, J.; Dore, U.; Orestano, D.; Pastore, F.; Tonazzo, A.; Tortora, L.; Booth, C.; Howlett, L.; Bogomilov, M.; Chizhov, M.; Kolev, D.; Tsenov, R.; Piperov, Stefan; Temnikov, P.; Apollonio, M.; Chimenti, P.; Giannini, G.; Burguet-Castell, J.; Cervera-Villanueva, A.; Gomez-Cadenas, J.J.; Martin-Albo, J.; Novella, P.; Sorel, M.; CERN. Geneva

    2008-01-01

    Measurements of the double-differential $\\pi^{\\pm}$ production cross-section in the range of momentum $100 \\MeVc \\leq p < 800 \\MeVc$ and angle $0.35 \\rad \\leq \\theta < 2.15 \\rad$ in proton--beryllium, proton--aluminium and proton--lead collisions are presented. The data were taken with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 \\GeVc to 12.9 \\GeVc hitting a target with a thickness of 5% of a nuclear interaction length. The tracking and identification of the produced particles was performed using a small-radius cylindrical time projection chamber (TPC) placed inside a solenoidal magnet. Incident particles were identified by an elaborate system of beam detectors. Results are obtained for the double-differential cross-sections at six incident proton beam momenta (3 \\GeVc, 5 \\GeVc, 8 \\GeVc, 8.9 \\GeVc (Be only), 12 \\GeVc and 12.9 \\GeVc (Al only)) and compared to previously available data.

  11. High quality, giant crystalline-Ge stripes on insulating substrate by rapid-thermal-annealing of Sn-doped amorphous-Ge in solid-liquid coexisting region

    Directory of Open Access Journals (Sweden)

    Ryo Matsumura

    2015-06-01

    Full Text Available Formation of large-grain (≥30 μm Ge crystals on insulating substrates is strongly desired to achieve high-speed thin-film transistors. For this purpose, we propose the methods of Sn-doping into amorphous-Ge combined with rapid-thermal-annealing (RTA in the solid-liquid coexisting temperature region for the Ge-Sn alloy system. The densities of micro-crystal-nuclei formed in this temperature region become low by tuning the RTA temperature close to the liquidus curve, which enhances the lateral growth of GeSn. Thanks to the very small segregation coefficient of Sn, almost all Sn atoms segregate toward edges of the stripes during growth. Agglomeration of GeSn degrades the surface morphologies; however, it is significantly improved by lowering the initial Sn concentration. As a result, pure Ge with large crystal grains (∼40 μm with smooth surface are obtained by optimizing the initial Sn concentration as low as 3 ∼ 5%. Lateral growth lengths are further increased through decreasing the number of nuclei in stripes by narrowing stripe width. In this way, high-crystallinity giant Ge crystals (∼200 μm are obtained for the stripe width of 3 μm. This “Si-seed free” technique for formation of large-grain pure Ge crystals is very useful to realize high-performance thin-film devices on insulator.

  12. High quality, giant crystalline-Ge stripes on insulating substrate by rapid-thermal-annealing of Sn-doped amorphous-Ge in solid-liquid coexisting region

    Science.gov (United States)

    Matsumura, Ryo; Kai, Yuki; Chikita, Hironori; Sadoh, Taizoh; Miyao, Masanobu

    2015-06-01

    Formation of large-grain (≥30 μm) Ge crystals on insulating substrates is strongly desired to achieve high-speed thin-film transistors. For this purpose, we propose the methods of Sn-doping into amorphous-Ge combined with rapid-thermal-annealing (RTA) in the solid-liquid coexisting temperature region for the Ge-Sn alloy system. The densities of micro-crystal-nuclei formed in this temperature region become low by tuning the RTA temperature close to the liquidus curve, which enhances the lateral growth of GeSn. Thanks to the very small segregation coefficient of Sn, almost all Sn atoms segregate toward edges of the stripes during growth. Agglomeration of GeSn degrades the surface morphologies; however, it is significantly improved by lowering the initial Sn concentration. As a result, pure Ge with large crystal grains (˜40 μm) with smooth surface are obtained by optimizing the initial Sn concentration as low as 3 ˜ 5%. Lateral growth lengths are further increased through decreasing the number of nuclei in stripes by narrowing stripe width. In this way, high-crystallinity giant Ge crystals (˜200 μm) are obtained for the stripe width of 3 μm. This "Si-seed free" technique for formation of large-grain pure Ge crystals is very useful to realize high-performance thin-film devices on insulator.

  13. Large-angle production of charged pions by 3 GeV/c - 12.9 GeV/c protons on beryllium, aluminium and lead targets

    CERN Document Server

    Catanesi, M G; Edgecock, R; Ellis, Malcolm; Soler, F J P; Gössling, C; Bunyatov, S; Krasnoperov, A; Popov, B; Serdiouk, V; Tereschenko, V; Di Capua, E; Vidal-Sitjes, G; Artamonov, A; Giani, S; Gilardoni, S; Gorbunov, P; Grant, A; Grossheim, A; Ivanchenko, V; Kayis-Topaksu, A; Panman, J; Papadopoulos, I; Chernyaev, E; Tsukerman, I; Veenhof, R; Wiebusch, C; Zucchelli, P; Blondel, A; Borghi, S; Morone, M C; Prior, G; Schroeter, R; Meurer, C; Gastaldi, U; Mills, G B; Graulich, J S; Grégoire, G; Bonesini, M; Ferri, F; Kirsanov, M; Bagulya, A; Grichine, V; Polukhina, N; Palladino, V; Coney, L; Schmitz, D; Barr, G; De Santo, A; Bobisut, F; Gibin, D; Guglielmi, A; Mezzetto, M; Dumarchez, J; Dore, U; Orestano, D; Pastore, F; Tonazzo, A; Tortora, L; Booth, C; Howlett, L; Bogomilov, M; Chizhov, M; Kolev, D; Tsenov, R; Piperov, Stefan; Temnikov, P; Apollonio, M; Chimenti, P; Giannini, G; Burguet-Castell, J; Cervera-Villanueva, A; Gómez-Cadenas, J J; Martín-Albo, J; Novella, P; Sorel, M; CERN. Geneva

    2008-01-01

    Measurements of the double-differential $\\pi^{\\pm}$ production cross-section in the range of momentum $100 \\MeVc \\leq p < 800 \\MeVc$ and angle $0.35 \\rad \\leq \\theta < 2.15 \\rad$ in proton--beryllium, proton--aluminium and proton--lead collisions are presented. The data were taken with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 \\GeVc to 12.9 \\GeVc hitting a target with a thickness of 5% of a nuclear interaction length. The tracking and identification of the produced particles was performed using a small-radius cylindrical time projection chamber (TPC) placed inside a solenoidal magnet. Incident particles were identified by an elaborate system of beam detectors. Results are obtained for the double-differential cross-sections at six incident proton beam momenta (3 \\GeVc, 5 \\GeVc, 8 \\GeVc, 8.9 \\GeVc (Be only), 12 \\GeVc and 12.9 \\GeVc (Al only)) and compared to previously available data.

  14. Crystal structure of the Nd(Ru{sub 0.6}Ge{sub 0.4}){sub 2} and ErRuGe compounds

    Energy Technology Data Exchange (ETDEWEB)

    Rizzoli, C.; Sologub, O.; Salamakha, P

    2003-02-17

    Using X-ray powder and single crystal diffraction, the crystal structures of the Nd(Ru{sub 0.6}Ge{sub 0.4}){sub 2} and ErRuGe compounds were investigated. The compounds belong to the KHg{sub 2} and TiNiSi type structure, respectively.

  15. Superconducting state of filled-skutterudite RPt{sub 4}Ge{sub 12} (R = La, Pr): {sup 73}Ge-NQR studies

    Energy Technology Data Exchange (ETDEWEB)

    Kanetake, F., E-mail: kanetake@nmr.mp.es.osaka-u.ac.j [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Mukuda, H.; Kitaoka, Y. [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Sugawara, H.; Magishi, K. [Faculty of Integrated Arts and Sciences, University of Tokushima, Tokushima 770-8502 (Japan); Itoh, K.M. [Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522 (Japan); Haller, E.E. [University of California at Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2010-12-15

    We report {sup 73}Ge-NQR studies on filled-skutterudite superconductors LaPt{sub 4}Ge{sub 12} and PrPt{sub 4}Ge{sub 12} under zero external field. In PrPt{sub 4}Ge{sub 12}, the measurement of the nuclear spin-lattice relaxation rate 1/T{sub 1} has revealed a distinct coherence peak just below T{sub c} followed by an exponential decrease well below T{sub c}, evidencing that PrPt{sub 4}Ge{sub 12} is an s-wave superconductor with the isotropic gap in a weak-coupling regime. In LaPt{sub 4}Ge{sub 12}, the 1/T{sub 1} exhibits the exponential decrease well below T{sub c}, suggesting the isotropic s-wave superconductivity. Even though {sup 73}Ge-NQR-1/T{sub 1} in LaPt{sub 4}Ge{sub 12} has been measured under zero field, its coherence peak was absent, which contrasts with the result in Pr-compound. This may point to a possible anisotropy in the Fermi surface and/or some damping effect of quasiparticles in association with electron-phonon interactions.

  16. Single and multi-photon events with missing energy in $e^+ e^-$ collisions at 161 GeV < $\\sqrt{s}$ < 172 GeV

    CERN Document Server

    Acciarri, M; Aguilar-Benítez, M; Ahlen, S P; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alverson, G; Alviggi, M G; Ambrosi, G; Anderhub, H; Andreev, V P; Angelescu, T; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Baksay, L; Banerjee, S; Banerjee, Sw; Banicz, K; Barczyk, A; Barillère, R; Barone, L; Bartalini, P; Baschirotto, A; Basile, M; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Bhattacharya, S; Biasini, M; Biland, A; Bilei, G M; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böck, R K; Böhm, A; Boldizsar, L; Borgia, B; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brigljevic, V; Brock, I C; Buffini, A; Buijs, A; Burger, J D; Burger, W J; Busenitz, J K; Button, A M; Cai, X D; Campanelli, M; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Castellini, G; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada-Canales, M; Cesaroni, F; Chamizo-Llatas, M; Chang, Y H; Chaturvedi, U K; Chekanov, S V; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chéreau, X J; Chiefari, G; Chien, C Y; Cifarelli, Luisa; Cindolo, F; Civinini, C; Clare, I; Clare, R; Cohn, H O; Coignet, G; Colijn, A P; Colino, N; Commichau, V; Costantini, S; Cotorobai, F; de la Cruz, B; Csilling, Akos; Dai, T S; D'Alessandro, R; De Asmundis, R; Degré, A; Deiters, K; Della Volpe, D; Denes, P; De Notaristefani, F; DiBitonto, Daryl; Diemoz, M; Van Dierendonck, D N; Di Lodovico, F; Dionisi, C; Dittmar, Michael; Dominguez, A; Doria, A; Dova, M T; Duchesneau, D; Duinker, P; Durán, I; Dutta, S; Easo, S; Efremenko, Yu V; El-Mamouni, H; Engler, A; Eppling, F J; Erné, F C; Ernenwein, J P; Extermann, Pierre; Fabre, M; Faccini, R; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Fenyi, B; Ferguson, T; Ferroni, F; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisk, I; Forconi, G; Fredj, L; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gau, S S; Gentile, S; Gheordanescu, N; Giagu, S; Goldfarb, S; Goldstein, J; Gong, Z F; Gougas, Andreas; Gratta, Giorgio; Grünewald, M W; Gupta, V K; Gurtu, A; Gutay, L J; Hartmann, B; Hasan, A; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Van Hoek, W C; Hofer, H; Hong, S J; Hoorani, H; Hou, S R; Hu, G; Innocente, Vincenzo; Jenkes, K; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Kasser, A; Khan, R A; Kamrad, D; Kamyshkov, Yu A; Kapustinsky, J S; Karyotakis, Yu; Kaur, M; Kienzle-Focacci, M N; Kim, D; Kim, D H; Kim, J K; Kim, S C; Kim, Y G; Kinnison, W W; Kirkby, A; Kirkby, D; Kirkby, Jasper; Kiss, D; Kittel, E W; Klimentov, A; König, A C; Kopp, A; Korolko, I; Koutsenko, V F; Krämer, R W; Krenz, W; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lapoint, C; Lassila-Perini, K M; Laurikainen, P; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Leonardi, E; Levchenko, P M; Li Chuan; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lu, W; Lü, Y S; Lübelsmeyer, K; Luci, C; Luckey, D; Luminari, L; Lustermann, W; Ma Wen Gan; Maity, M; Majumder, G; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mangla, S; Marchesini, P A; Marin, A; Martin, J P; Marzano, F; Massaro, G G G; McNally, D; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Von der Mey, M; Mi, Y; Mihul, A; Van Mil, A J W; Mirabelli, G; Mnich, J; Molnár, P; Monteleoni, B; Moore, R; Morganti, S; Moulik, T; Mount, R; Müller, S; Muheim, F; Muijs, A J M; Nahn, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nippe, A; Nisati, A; Nowak, H; Oh, Yu D; Opitz, H; Organtini, G; Ostonen, R; Palomares, C; Pandoulas, D; Paoletti, S; Paolucci, P; Park, H K; Park, I H; Pascale, G; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Peach, D; Pei, Y J; Pensotti, S; Perret-Gallix, D; Petersen, B; Petrak, S; Pevsner, A; Piccolo, D; Pieri, M; Pinto, J C; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Postema, H; Produit, N; Prokofev, D; Prokofiev, D O; Rahal-Callot, G; Raja, N; Rancoita, P G; Rattaggi, M; Raven, G; Razis, P A; Read, K; Ren, D; Rescigno, M; Reucroft, S; Van Rhee, T; Riemann, S; Riles, K; Robohm, A; Rodin, J; Roe, B P; Romero, L; Rosier-Lees, S; Rosselet, P; Van Rossum, W; Roth, S; Rubio, Juan Antonio; Ruschmeier, D; Rykaczewski, H; Salicio, J; Sánchez, E; Sanders, M P; Sarakinos, M E; Sarkar, S; Sassowsky, M; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schmitz, P; Scholz, N; Schopper, Herwig Franz; Schotanus, D J; Schwenke, J; Schwering, G; Sciacca, C; Sciarrino, D; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shukla, J; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Sopczak, André; Smith, B; Spillantini, P; Steuer, M; Stickland, D P; Stone, A; Stone, H; Stoyanov, B; Strässner, A; Strauch, K; Sudhakar, K; Sultanov, G G; Sun, L Z; Susinno, G F; Suter, H; Swain, J D; Tang, X W; Tauscher, Ludwig; Taylor, L; Ting, Samuel C C; Ting, S M; Tonutti, M; Tonwar, S C; Tóth, J; Tully, C; Tuchscherer, H; Tung, K L; Uchida, Y; Ulbricht, J; Uwer, U; Valente, E; Van de Walle, R T; Vesztergombi, G; Vetlitskii, I; Viertel, Gert M; Vivargent, M; Völkert, R; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Vorvolakos, A; Wadhwa, M; Wallraff, W; Wang, J C; Wang, X L; Wang, Z M; Weber, A; Wittgenstein, F; Wu, S X; Wynhoff, S; Xu, J; Xu, Z Z; Yang, B Z; Yang, C G; Yao, X Y; Ye, J B; Yeh, S C; You, J M; Zalite, A; Zalite, Yu; Zemp, P; Zeng, Y; Zhang, Z; Zhang, Z P; Zhou, B; Zhu, G Y; Zhu, R Y; Zichichi, Antonino; Ziegler, F

    1997-01-01

    A search for single and multi-photon events with missing energy is performed using data collected at centre-of-mass energies between 161 GeV and 172 GeV for a total of 20.9 pb$^{-1}$ of integrated luminosity. The results obtained are used to derive the value for the $\

  17. High-temperature heat capacity of YBiGeO5 and GdBiGeO5 in the range 373-1000 K

    Science.gov (United States)

    Denisova, L. T.; Belousova, N. V.; Galiakhmetova, N. A.; Denisov, V. M.

    2017-05-01

    The oxide YBiGeO5 and GdBiGeO5 compounds have been synthesized by solid-phase synthesis. The high-temperature heat capacity has been measured using differential scanning calorimetry in the range 373-1000 K. The results were used to calculate the thermodynamic properties (the change in the enthalpy and entropy).

  18. Ge/GeO2-Ordered Mesoporous Carbon Nanocomposite for Rechargeable Lithium-Ion Batteries with a Long-Term Cycling Performance.

    Science.gov (United States)

    Zeng, Lingxing; Huang, Xiaoxia; Chen, Xi; Zheng, Cheng; Qian, Qingrong; Chen, Qinghua; Wei, Mingdeng

    2016-01-13

    Germanium-based nanostructures are receiving intense interest in lithium-ion batteries because they have ultrahigh lithium ion storage ability. However, the Germanium-based anodes undergo the considerably large volume change during the charge/discharge processes, leading to a fast capacity fade. In the present work, a Ge/GeO2-ordered mesoporous carbon (Ge/GeO2-OMC) nanocomposite was successfully fabricated via a facile nanocasting route by using mesoporous carbon as a nanoreactor, and was then used as an anode for lithium-ion batteries. Benefited from its unique three-dimensional "meso-nano" structure, the Ge/GeO2-OMC nanocomposite exhibited large reversible capacity, excellent long-time cycling stability and high rate performance. For instance, a large reversible capacity of 1018 mA h g(-1) was obtained after 100 cycles at a current density of 0.1 A g(-1), which might be attributed to the unique structure of the Ge/GeO2-OMC nanocomposite. In addition, a reversible capacity of 492 mA h g(-1) can be retained when cycled to 500 cycles at a current density of 1 A g(-1).

  19. GE Smart Prep半自动监控软件的应用要点%Application Keypoints of GE Light Speed 8 Smart Prep Semiautomatic Monitoring Software

    Institute of Scientific and Technical Information of China (English)

    肖建明

    2011-01-01

    目的 探讨GE light speed 8 smart Prep技术在CT血管造影中的准确应用.方法 采用GE light speed 8 Smart Pmp软件对35例患者进行颅脑CTA检查.结果 总结出GE light speed 8运用smart prep 的技术要点.%Objective To investigate the application of the GE light speed 8 smart prep technique in CT angiography. Methods Used GE light speed 8 Smart Prep software to assist the check of cerebral CTA in 35 patients. Results Summarized the application keypoints of CE light speed 8 smart prep technique.

  20. TEM studies of Ge nanocrystal formation in PECVD grown SiO{sub 2}:Ge/SiO{sub 2} multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Agan, S [Physics Department, Kirikkale University, 71450 Kirikkale (Turkey); Dana, A [Physics Department, Bilkent University, 06800 Ankara (Turkey); Aydinli, A [Physics Department, Bilkent University, 06800 Ankara (Turkey)

    2006-06-07

    We investigate the effect of annealing on the Ge nanocrystal formation in multilayered germanosilicate-oxide films grown on Si substrates by plasma enhanced chemical vapour deposition (PECVD). The multilayered samples were annealed at temperatures ranging from 750 to 900 {sup 0}C for 5 min under nitrogen atmosphere. The onset of formation of Ge nanocrystals, at 750 {sup 0}C, can be observed via high resolution TEM micrographs. The diameters of Ge nanocrystals were observed to be between 5 and 14 nm. As the annealing temperature is raised to 850 {sup 0}C, a second layer of Ge nanocrystals forms next to the original precipitation band, positioning itself closer to the substrate SiO{sub 2} interface. High resolution cross section TEM images, electron diffraction and electron energy-loss spectroscopy as well as energy-dispersive x-ray analysis (EDAX) data all indicate that Ge nanocrystals are present in each layer.