Monolithic integration of AlGaInP laser diodes on SiGe/Si substrates by molecular beam epitaxy

International Nuclear Information System (INIS)

Kwon, O.; Boeckl, J. J.; Lee, M. L.; Pitera, A. J.; Fitzgerald, E. A.; Ringel, S. A.

2006-01-01

Room temperature operation of visible AlGaInP laser diodes epitaxially integrated on Si was demonstrated. Compressively strained laser heterostructures were grown by molecular beam epitaxy (MBE) on low dislocation density SiGe/Si substrates, where the threading dislocation density of the top relaxed Ge layers was measured in the range of 2x10 6 cm -2 . A threshold current density of J th ∼1.65 kA/cm 2 for the as-cleaved, gain-guided AlGaInP laser grown on SiGe/Si was obtained at the peak emission wavelength of 680 nm under pulsed mode current injection. These results show that not only can high quality AlGaInP materials grown by MBE be achieved on Si via relaxed SiGe interlayers, but the prototype demonstration of laser diode operation on Si illustrates that very defect sensitive optoelectronics in the III-P system can indeed be integrated with Si substrates by heteroepitaxial methods

Effect of 60Co γ-irradiation on structural and optical properties of thin films of Ga10Se80Hg10

Science.gov (United States)

Ahmad, Shabir; Asokan, K.; Shahid Khan, Mohd.; Zulfequar, M.

2015-08-01

Thin films of Ga10Se80Hg10 have been deposited onto a chemically cleaned Al2O3 substrates by thermal evaporation technique under vacuum. The investigated thin films are irradiated by 60Co γ-rays in the dose range of 50-150 kGy. X-ray diffraction patterns of the investigated thin films confirm the preferred crystallite growth occurs in the tetragonal phase structure. It also shows, the average crystallite size increases after γ-exposure, which indicates the crystallinity of the material increases after γ-irradiation. These results were further supported by surface morphological analysis carried out by scanning electron microscope and atomic force microscope which also shows the crystallinity of the material increases with increasing the γ-irradiation dose. The optical transmission spectra of the thin films at normal incidence were investigated in the spectral range from 190 to 1100 nm. Using the transmission spectra, the optical constants like refractive index (n) and extinction coefficient (k) were calculated based on Swanepoel's method. The optical band gap (Eg) was also estimated using Tauc's extrapolation procedure. The optical analysis shows: the value of optical band gap of investigated thin films decreases and the corresponding absorption coefficient increases continuously with increasing dose of γ-irradiation.

Fabrication of high quality GaAs-on-insulator via ion-cut of epitaxial GaAs/Ge heterostructure

Energy Technology Data Exchange (ETDEWEB)

Chang, Yongwei; Zhang, Miao [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Deng, Chuang; Men, Chuanling [School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Chen, Da [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Zhu, Lei; Yu, Wenjie; Wei, Xing [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Di, Zengfeng, E-mail: zfdi@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Wang, Xi [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

2015-08-15

Highlights: • GaAs-on-insulator has been achieved by integrating of epitaxy, ion-cut and selective chemical etching. • Superior to the direct ion-cut of bulk GaAs layer with the H implantation fluence 2.0 × 10{sup 17} cm{sup −2}, the fabrication of GaAs-on-insulator by the transfer of GaAs/Ge heterostructure only needs H implantation fluence as low as 0.8 × 10{sup 17} cm{sup −2}. • The crystalline quality of the top GaAs layer of the final GaAs-on-insulator wafer is not affected by the implantation process and comparable to the as-grown status. - Abstract: Due to the extraordinary electron mobility, III–V compounds are considered as the ideal candidate channel materials for future electronic devices. In this study, a novel approach for the fabrication of high-crystalline quality GaAs-on-insulator has been proposed by integrating of ion-cut and selective chemical etching. GaAs layer with good crystalline quality has been epitaxially grown on Ge by molecular beam epitaxy (MBE). With H implantation and wafer bonding process, the GaAs/Ge heterostructure is transferred onto silicon dioxide wafer after the proper thermal treatment. Superior to the direct ion-cut of GaAs layer, which requires the H implantation fluence as high as 2.0 × 10{sup 17} cm{sup −2}, the transfer of GaAs/Ge heterostructure in the present study only needs the implantation of 0.8 × 10{sup 17} cm{sup −2} H ions. GaAs-on-insulator structure was successfully achieved by the selective chemical etching of defective Ge layer using SF{sub 6} plasma. As the GaAs/Ge heterostructure can be easily epitaxy grown on silicon platform, the proposed approach for GaAs-on-insulator manufacturing is rather compatible with mature Si integrated circuits (ICs) technology and thus can be integrated to push the microelectronic technology to post-Si era.

Fabrication of high quality GaAs-on-insulator via ion-cut of epitaxial GaAs/Ge heterostructure

International Nuclear Information System (INIS)

Chang, Yongwei; Zhang, Miao; Deng, Chuang; Men, Chuanling; Chen, Da; Zhu, Lei; Yu, Wenjie; Wei, Xing; Di, Zengfeng; Wang, Xi

2015-01-01

Highlights: • GaAs-on-insulator has been achieved by integrating of epitaxy, ion-cut and selective chemical etching. • Superior to the direct ion-cut of bulk GaAs layer with the H implantation fluence 2.0 × 10 17 cm −2 , the fabrication of GaAs-on-insulator by the transfer of GaAs/Ge heterostructure only needs H implantation fluence as low as 0.8 × 10 17 cm −2 . • The crystalline quality of the top GaAs layer of the final GaAs-on-insulator wafer is not affected by the implantation process and comparable to the as-grown status. - Abstract: Due to the extraordinary electron mobility, III–V compounds are considered as the ideal candidate channel materials for future electronic devices. In this study, a novel approach for the fabrication of high-crystalline quality GaAs-on-insulator has been proposed by integrating of ion-cut and selective chemical etching. GaAs layer with good crystalline quality has been epitaxially grown on Ge by molecular beam epitaxy (MBE). With H implantation and wafer bonding process, the GaAs/Ge heterostructure is transferred onto silicon dioxide wafer after the proper thermal treatment. Superior to the direct ion-cut of GaAs layer, which requires the H implantation fluence as high as 2.0 × 10 17 cm −2 , the transfer of GaAs/Ge heterostructure in the present study only needs the implantation of 0.8 × 10 17 cm −2 H ions. GaAs-on-insulator structure was successfully achieved by the selective chemical etching of defective Ge layer using SF 6 plasma. As the GaAs/Ge heterostructure can be easily epitaxy grown on silicon platform, the proposed approach for GaAs-on-insulator manufacturing is rather compatible with mature Si integrated circuits (ICs) technology and thus can be integrated to push the microelectronic technology to post-Si era

Mass-spectrometric and optimal study of products from the laser ablated PbTe(Ga)

International Nuclear Information System (INIS)

Mikhajlov, V.A.; Putilin, F.N.; Trubnikov, D.N.

1994-01-01

The products of evaporation (p=10 -7 Torr) of a PbTe(Ga) target ablated by the Nd 3+ : YA laser (λ=1.08 μm, τ=15 ns, w=0.47-4.8 Jxcm -2 ) have been studied using quadrupole mass spectrometry and optical spectroscopy. The neutral Pb, Te, Ga, Te 2 , PbTe and the singly charged ions of Pb, Te, Ga have been detected by mass spectrometry. The lines of Pb 1 , Pb 2 , Te 2 and Ga 1 have been observed in the region of 340-760 nm of the emission spectra, the lines of Pb 3 and Te 3 were absent. The kinetic energy of the ions has been estimated using the ion optics system decelerated and focused ions with the selected energy

A 10-GeV, 5-MW proton source for a pulsed spallation source

International Nuclear Information System (INIS)

Cho, Y.; Chae, Y.C.; Crosbie, E.

1995-01-01

A feasibility study for a pulsed spallation source based on a 5-MW, 10-GeV rapid proton synchrotron (RCS) is in progress. The integrated concept and performance parameters of the facility are discussed. The 10-GeV synchrotron uses as its injector the 2-GeV accelerator system of a 1-MW source described elsewhere. The 1-MW source accelerator system consists of a 400-MeV H - linac with 2.5 MeV energy spread in the 75% chopped (25% removed) beam and a 30-Hz RCS that accelerates the 400-MeV beam to 2 GeV. The time averaged current of the accelerator system is 0.5 mA, equivalent to 1.04 x 10 14 protons per pulse. The 10-GeV RCS accepts the 2 GeV beam and accelerates it to 10 GeV. Beam transfer from the 2-GeV synchrotron to the 10-GeV machine u highly efficient bunch-to-bucket injection, so that the transfer can be made without beam loss. The synchrotron lattice uses FODO cells of 90 degrees phase advance. Dispersion-free straight sections are obtained using a missing magnet scheme. The synchrotron magnets are powered by dual-frequency resonant circuits. The magnets are excited at a 20-Hz rate and de-excited at 60-Hz. resulting in an effective 30-Hz rate. A key feature of the design of this accelerator system is that beam losses are minimized from injection to extraction, reducing activation to levels consistent with hands-on maintenance. Details of the study are presented

High spin levels in 66Ga, 68Ga, 70Ga and 68Ge, 70Ge, 72Ge via fusion evaporation reactions induced by α-particles

International Nuclear Information System (INIS)

Morand, C.

1979-01-01

The high spin (J 70 Ga all the members (except the 3 - one) of the (πpsub(3/2), νgsub(9/2)) configuration have been identified, in addition with the (πfsub(5/2), νgsub(9/2))sub(7 - ) and (πgsub(9/2), νgsub(9/2))sub(9 + ) states. In 66 Ga and 68 Ga most of the levels with J>7 ca be described as a result of maximum coupling of a gsub(9/2) neutron with the odd Ga core. Thus the (πgsub(9/2), νgsub(9/2))sub(9 + ) states have been safely located. In the same way the even Ge, the backbending effect at the Jsup(π)=8 + state is less and less pronouced from the 68 Ge to the 72 Ge; that can be explained by the (νgsub(9/2)) 2 sub(8 + ) configuration of this state, so that the 8 + →6 + γ-transition is more and more allowed with increasing N, i.e. as the νgsub(9/2) shell acts more and more in the lower yrast levels Jsup(π)=0 + , 2 + , 4 + , 6 + configurations [fr

Band alignment study of lattice-matched In{sub 0.49}Ga{sub 0.51}P and Ge using x-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Owen, Man Hon Samuel, E-mail: m.owen.sg@ieee.org, E-mail: yeo@ieee.org; Zhou, Qian; Gong, Xiao; Yeo, Yee-Chia, E-mail: m.owen.sg@ieee.org, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 119260 (Singapore); Zhang, Zheng; Pan, Ji Sheng [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Loke, Wan Khai; Wicaksono, Satrio; Yoon, Soon Fatt [School of Electrical and Electronic Engineering, Nanyang Technological University (NTU), Nanyang Avenue, Singapore 639798 (Singapore); Tok, Eng Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

2014-09-08

Lattice-matched In{sub 0.49}Ga{sub 0.51}P was grown on a p-type Ge(100) substrate with a 10° off-cut towards the (111) by low temperature molecular beam epitaxy, and the band-alignment of In{sub 0.49}Ga{sub 0.51}P on Ge substrate was obtained by high resolution x-ray photoelectron spectroscopy. The valence band offset for the InGaP/Ge(100) interface was found to be 0.64 ± 0.12 eV, with a corresponding conduction band offset of 0.60 ± 0.12 eV. The InGaP/Ge interface is found to be of the type I band alignment.

Photoluminescence of polycrystalline CuIn 0.5 Ga 0.5 Te 2 thin films grown by flash evaporation

KAUST Repository

Yandjah, L.

2018-04-03

Polycrystalline CuIn0.5Ga0.5Te2 films were deposited by flash evaporation from ingot prepared by reacting, in stoichiometric proportions, high purity Cu, In, Ga and Te elements in vacuum sealed quartz . The as-obtained films were characterized by X – ray diffraction (XRD), transmission electron microscopy (TEM) combined with energy dispersive spectroscopy (EDS). XRD and TEM results showed that the layer has a chalcopyrite-type structure, predominantly oriented along (112) planes, with lattice parameters a = 0.61 nm and c = 1.22 nm. The optical properties in the near - infrared and visible range 600 - 2400 nm have been studied. The analysis of absorption coefficient yielded an energy gap value of 1.27 eV. Photoluminescence analysis of as-grown sample shows two main emission peaks located at 0.87 and 1.19 eV at 4 K.

Stopping power of charged particles from 10 eV/amu to 10 GeV/amu

International Nuclear Information System (INIS)

Nakane, Yoshihiro; Tanaka, Shun-ichi; Furihata, Shiori; Iwai, Satoshi.

1993-08-01

Electric collision, nuclear collision and total stopping powers in 10 kinds of elements: H 2 , He, Be, C, Al, Fe, Cu, W, Pb and U, and 4 kinds of materials: water, phantom, LiF-TLD and SSNTD (solid state neutron track detector) have been calculated for 10 kinds of charged particles from 10 eV/amu to 10 GeV/amu with STOPPING, SPAR, and RSTAN/RSHEV codes, in which the charged particles are important projectiles for evaluating the dose and detector responses of radiations, and for accelerator shielding calculations. Calculated data are presented in Table and Figure. (author)

Denton E-beam Evaporator #2

Data.gov (United States)

Federal Laboratory Consortium — Description:CORAL Name: E-Beam Evap 2This is an electron gun evaporator for the deposition of metals and dielectrics thin films. Materials available are: Ag, Al, Au,...

Strain relaxation of CdTe on Ge studied by medium energy ion scattering

Energy Technology Data Exchange (ETDEWEB)

Pillet, J.C., E-mail: jean-christophe.pillet@cea.fr [Univ. Grenoble Alpes, CEA, LETI, MINATEC campus, F38000 Grenoble (France); CEA, LETI, Département Optique et Photonique, F38054 Grenoble (France); Pierre, F. [Univ. Grenoble Alpes, CEA, LETI, MINATEC campus, F38000 Grenoble (France); CEA, LETI, Service de Caractérisation des Matériaux et Composants, F38054 Grenoble (France); Jalabert, D. [Univ. Grenoble Alpes, CEA, LETI, MINATEC campus, F38000 Grenoble (France); CEA-INAC/UJF-Grenoble 1 UMR-E, SP2M, LEMMA, Minatec Grenoble F-38054 (France)

2016-10-01

We have used the medium energy ion scattering (MEIS) technique to assess the strain relaxation in molecular-beam epitaxial (MBE) grown CdTe (2 1 1)/Ge (2 1 1) system. A previous X-ray diffraction study, on 10 samples of the same heterostructure having thicknesses ranging from 25 nm to 10 μm has allowed the measurement of the strain relaxation on a large scale. However, the X-ray diffraction measurements cannot achieve a stress measurement in close proximity to the CdTe/Ge interface at the nanometer scale. Due to the huge lattice misfit between the CdTe and Ge, a high degree of disorder is expected at the interface. The MEIS in channeling mode is a good alternative in order to profile defects with a high depth resolution. For a 21 nm thick CdTe layer, we observed, at the interface, a high density of Cd and/or Te atoms moved from their expected crystallographic positions followed by a rapid recombination of defects. Strain relaxation mechanisms in the vicinity of the interface are discussed.

Non-isothermal crystallization kinetics of As{sub 30}Te{sub 60}Ga{sub 10} glass

Energy Technology Data Exchange (ETDEWEB)

Mohamed, Mansour; Abd-Elnaiem, Alaa M.; Abdel-Rahim, M.A.; Hafiz, M.M. [Assiut University, Physics Department, Faculty of Science, Assiut (Egypt); Hassan, R.M. [Assiut University, Physics Department, Faculty of Science, Assiut (Egypt); Aden University, Physics Department, Faculty of Education-Zingiber, Aden (Yemen)

2017-08-15

The crystallization study under non-isothermal conditions of As{sub 30}Te{sub 60}Ga{sub 10} glass was investigated. The studied composition was synthesized by melt-quenching technique and characterized by different techniques such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The XRD analysis revealed that the as-prepared and annealed bulk glass of As{sub 30}Te{sub 60}Ga{sub 10} exhibit the amorphous, and polycrystalline nature, respectively. The DSC results showed that the heating rate affects the characteristic temperatures, for instance, the glass transition, onset, and peak crystallization temperatures. Furthermore, some thermal analysis methods such as the Kissinger and Matusita et al., approximations were employed to determine the crystallization parameters: for example Avrami exponent and the activation energies for glass transition and crystallization process. In addition, we have compared the experimental DSC data with the calculated ones based on the Johnson-Mehl-Avrami (JMA) and Sestak-Berggren SB(M,N) models. The results indicated that the SB(M,N) model is more suitable for describing the non-isothermal crystallization kinetics of the investigated composition. (orig.)

Ga-Bi-Te system

International Nuclear Information System (INIS)

Rustamov, P.G.; Seidova, N.A.; Shakhbazov, M.G.; AN Azerbajdzhanskoj SSR, Baku. Inst. Neorganicheskoj i Fizicheskoj Khimii)

1976-01-01

To elucidate the nature of interaction in the system Ga-Bi-Te, a study has been made of sections GaTe-Bi 2 Te 3 , Ga 2 Te 3 -Bi, GaTe-Bi and Bi 2 Te 3 -Ga. The alloys have been prepared by direct melting of the components or their alloys with subsequent homogenizin.o annealing at 400 deg C. The study has been made by the methods of differential thermal, microstructural analysis and by microhardness measurements. On the basis of literature data and data obtained a projection of the liquidus surface of the phase diagram for the system Ga-Bi-Te has been constructed. In the ternary system there are 17 curves of monovariant equilibrium dividing the liquidus into 10 fields of primary crystallization of phases, 9 points of non-variant equilibrium of which 4 points are triple eutectics and 5 points are triple peritectics

Double stage crystallization of bulk Ge20Te80 glass

International Nuclear Information System (INIS)

Parthasarathy, G.; Bandyopadhyay, A.K.; Gopal, E.S.R.; Subbanna, G.N.

1984-01-01

The growing interest of the semiconducting glasses is partly because of their interesting electrical and optical properties. These properties are usually connected with their crystallization. In many glasses, the glass-supercooled liquid transition precedes crystallization. The glass transition temperature (Tsub(g)) is found to exhibit multistage processes for a few systems. In this communication, we report the observation of a double Tsub(g) effect in bulk Ge 20 Te 80 glass and also explain the structural changes taking place in the two stages. (author)

Nano-crystalline p-ZnGa{sub 2}Te{sub 4}/n-Si as a new heterojunction diode

Energy Technology Data Exchange (ETDEWEB)

Sakr, G.B. [Nano-Science Lab., Department of Physics, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Fouad, S.S. [Department of Physics, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Yahia, I.S., E-mail: dr_isyahia@yahoo.com [Nano-Science Lab., Department of Physics, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Semicondcutor Lab., Department of Physics, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); Abdel Basset, D.M. [Department of Physics, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Yakuphanoglu, F. [Physics Department, Faculty of Science and Arts, Firat University, Elazig (Turkey)

2013-02-15

Graphical abstract: Display Omitted Highlights: ► ZnGa{sub 2}Te{sub 4}/Si thin film was prepared by thermal evaporation technique. ► XRD and AFM graphs support the nano-crystalline of the studied device. ► Dark current–voltage characteristics of the heterojunction diode were investigated. ► Electrical parameters and conduction mechanism were determined. ► Conduction mechanisms were controlled by TE, SCLC and TCLC. -- Abstract: In this communication, ZnGa{sub 2}Te{sub 4} thin film was prepared by thermal evaporation technique on n-Si substrate. P-ZnGa{sub 2}Te{sub 4}/n-Si heterojunction diode was fabricated. The structure of ZnGa{sub 2}Te{sub 4} thin film was checked by XRD pattern and confirmed by AFM micrographs. The dark current–voltage characteristics of the heterojunction diode were investigated to determine the electrical parameters and conduction mechanism as a function of forward and reverse biasing conditions in the range (−10 V to 10 V) at temperature interval (303–423 K). The conduction mechanism was controlled by thermionic emission, space charge limited (SCLC) and trap-charge limited current (TCLC) mechanisms. The basic parameters such as the series resistance R{sub s}, the shunt resistance R{sub sh}, the ideality factor n and the barrier height φ{sub b} of the diode, the total density of trap states N{sub 0} and the exponential trapping distribution P{sub o} were determined. The obtained results showed that ZnGa{sub 2}Te{sub 4} is a good candidate for the applications of electronic devices.

Semipolar MOVPE AlGaN on (10 anti 10) m-plane sapphire; MOVPE von semipolarem AlGaN auf (10 anti 10) m-plane Saphir

Energy Technology Data Exchange (ETDEWEB)

Mehnke, Frank; Stellmach, Joachim; Frentrup, Martin; Kusch, Gunnar; Wernicke, Tim; Pristovsek, Markus; Kneissl, Michael [Technische Universitaet Berlin, Institut fuer Festkoerperphysik, Hardenbergstr. 36, 10623 Berlin (Germany)

2011-07-01

The energy gap of AlGaN varies between 3.4 eV and 6.2 eV and allows light emitting diodes (LED) in the ultraviolet spectral region. The authors studied semipolar (11 anti 22) AlGaN layers that were deposited on (10 anti 10) m-plane sapphire using MOVPE (metalorganic vapor phase epitaxy) without nucleation layer with a substrate temperature below 1100 C in H2 atmosphere. The layers are preferably (11 anti 22) oriented. The sample show a surface roughness between 15 and 2 nm. The Al content of the smoothest samples is about 60% determined by transmission experiments. Below 60% Al content a triangular morphology was observed, the opening angle increased with decreasing Al content. The absorption edge was 0.05 eV (GaN) to 0.35 eV (AlN) below the band edge of (0001) oriented AlGaN layers. Further investigations of semipolar AlGaN layers to study the applicability for UV LEDs are under preparation.

Study of optical properties of vacuum evaporated carbon nanotube containing Se80Te16Cu4 thin films

Science.gov (United States)

Upadhyay, A. N.; Tiwari, R. S.; Singh, Kedar

2016-08-01

Thin films of Se80Te16Cu4 glassy alloy and 3 wt.% of carbon nanotubes (CNTs) containing Se80Te16Cu4 glassy composite were deposited on clean glass substrate by thermal evaporation technique. The scanning electron microscope and energy dispersive x-ray analysis were performed to investigate the surface morphology and elemental composition of as synthesised samples. The reflectance and transmittance spectra of as-deposited thin films were recorded (200-1100 nm) by using UV/VIS/NIR spectrophotometer. The optical band gap and optical constants such as absorption coefficient (α), refractive index (n) and extinction coefficient (k) of Se80Te16Cu4 and 3 wt.% CNTs-Se80Te16Cu4 glassy composite thin films were calculated. It is observed that optical properties alter due to CNTs incorporation in Se80Te16Cu4 glassy alloy. Effect on optical properties due to CNTs incorporation can be explained in terms of concentration of unsaturated bonds/defects in the localised states.

Production of prototype 68Ge/68Ga generator in Iran

International Nuclear Information System (INIS)

Shirazi, B.; Fateh, B.; Mirzaii, M.; Aslani, Gh. R.

2007-01-01

Ga-68 is a radioisotope material with a half life of 68 min. As it has a specific decay mode, it is a positron emitter and hence, is popularly used in nuclear medicine. The only way to obtain these nuclides is to produce the mother nuclease which is Germanium-68. There are many nuclear reactions from which the Ge-68 is obtained, however, the best reaction is 6 9 G a(p, 2n) 6 8 G e . The cross section of this nuclear reaction was calculated with the ALICE-91 Code and the result was compared with the practical work made by other researchers, and it was acceptable. Having the cross sections in mind, the best proton energy was calculated to be between 20-25 MeV. Further research showed that Ga 2 O 3 is the best type of target material. Therefore, it was necessary to design and make a suitable target holder for these kind of compositions, which for the first time in Iran was demonstrated in the Atomic Energy Organization of Iran. The thickness of the target, bearing in mind the rate of energy loss inside the target material, was calculated with the SRIM Code and the Ga 2 O 3 tablets were made with FT-IR facilities at the Nuclear Research Center for Agriculture and Medicine (NRCAM). They were, then bombarded with 22.5 MeV proton energy and the beam currents of 2 and 10 μA. Two weeks after the bombardment the radio chemical separation of Ge-68 was accompolished with concentrated acid HN0 3 and by applying heat. Then, the acid solution was evaporated till dried, after that, an EDTA solution (0.005 M, pH=11) was added to recover the Ge-68. By passing the EDTA solution with the rate of 0.5 ml/min through the AI 2 O 3 column, the Ge-68 radioisotope was observed. Then, about 50 ml of EDTA (0.005 M, pH=11) was passed through the loaded column, where almost all the natural Gallium impurities were removed. The prepared generators were milked many times with EDTA solution (0.005 M, pH=8) and the leakage of Ge-68 nuclease and natural Gallium were determined. The average of the

γ astrophysics above 10-30 GeV with the MAGIC telescope

International Nuclear Information System (INIS)

Mirzoyan, Razmick

1999-01-01

The project on the 17 m oe telescope, dubbed MAGIC (Major Atmospheric Gamma Imaging Cherenkov Telescope), is dedicated for γ astrophysics in the energy range from 10-30 GeV till 50-100 TeV. MAGIC will for the first time allow to explore with very high sensitivity the energy range 10-300 GeV and to bridge the existing energy gap between satellite and ground-based air Cherenkov measurements. We believe MAGIC will serve as a prototype for future multi-telescope γ ray observatories

Novel Sn-Based Contact Structure for GeTe Phase Change Materials.

Science.gov (United States)

Simchi, Hamed; Cooley, Kayla A; Ding, Zelong; Molina, Alex; Mohney, Suzanne E

2018-05-16

Germanium telluride (GeTe) is a phase change material (PCM) that has gained recent attention because of its incorporation as an active material for radio frequency (RF) switches, as well as memory and novel optoelectronic devices. Considering PCM-based RF switches, parasitic resistances from Ohmic contacts can be a limiting factor in device performance. Reduction of the contact resistance ( R c ) is therefore critical for reducing the on-state resistance to meet the requirements of high-frequency RF applications. To engineer the Schottky barrier between the metal contact and GeTe, Sn was tested as an interesting candidate to alter the composition of the semiconductor near its surface, potentially forming a narrow band gap (0.2 eV) SnTe or a graded alloy with SnTe in GeTe. For this purpose, a novel contact stack of Sn/Fe/Au was employed and compared to a conventional Ti/Pt/Au stack. Two different premetallization surface treatments of HCl and deionized (DI) H 2 O were employed to make a Te-rich and Ge-rich interface, respectively. Contact resistance values were extracted using the refined transfer length method. The best results were obtained with DI H 2 O for the Sn-based contacts but HCl treatment for the Ti/Pt/Au contacts. The as-deposited contacts had the R c (ρ c ) of 0.006 Ω·mm (8 × 10 -9 Ω·cm 2 ) for Sn/Fe/Au and 0.010 Ω·mm (3 × 10 -8 Ω·cm 2 ) for Ti/Pt/Au. However, the Sn/Fe/Au contacts were thermally stable, and their resistance decreased further to 0.004 Ω·mm (4 × 10 -9 Ω·cm 2 ) after annealing at 200 °C. In contrast, the contact resistance of the Ti/Pt/Au stack increased to 0.012 Ω·mm (4 × 10 -8 Ω·cm 2 ). Transmission electron microscopy was used to characterize the interfacial reactions between the metals and GeTe. It was found that formation of SnTe at the interface, in addition to Fe diffusion (doping) into GeTe, is likely responsible for the superior performance of Sn/Fe/Au contacts, resulting in one of the lowest reported

Ga2O for target, solvent extraction for radiochemical separation and SnO2 for the preparation of a 68Ge/68Ga generator

International Nuclear Information System (INIS)

Aardaneh, K.; Walt, T.N. van der

2006-01-01

The target for the production of 68 Ge consists of a disc of gallium suboxide, Ga 2 O, with a 19 mm diameter. The suboxide was primarily prepared by repeatedly mixing metallic Ga and Ga 2 O 3 at 700 deg C. The target (2.4 g) was quite stable under a long-time irradiation with a 34 MeV proton beam at a current of ∼80 μA. The dissolution of the target was performed using 12M sulphuric acid solution, assisted with the dropwise addition of 30% H 2 O 2 solution, and took less than 4 hours. A solvent extraction method, using a 9M H 2 SO 4 - 0.3M HCl/CCl 4 system, was employed for the radiochemical separation of 68 Ge from Ga and Zn radionuclides, while 0.05M HCl was used for the back extraction of 68 Ge from the organic phase. The 68 Ge obtained in the dilute HCl was directly loaded onto a column containing either a hydrous tin dioxide or a crystalline tin dioxide, obtained by calcinations of the hydrous oxide at 450, 700, and 900 deg C. The calcinated hydrous tin dioxide at 900 deg C showed the highest crystallinity and highest 68 Ga elution yield and was selected for use in the generator. The 68 Ga elution from the column generator packed with 2 g of tin dioxide, using 3 ml of 1M HCl, and yielded an average of 65%. The breakthrough of 68 Ge was 6.1 x 10 -4 %. (author)

Development of high responsivity Ge:Ga photoconductors

International Nuclear Information System (INIS)

Haegel, N.M.; Hueschen, M.R.; Haller, E.E.

1984-06-01

Czochralski-grown gallium-doped germanium (Ge:Ga) single crystal samples with a compensation of 10 -4 have been modified by the indiffusion of Cu to produce photoconductors which provide NEPs comparable to current optimum Ge:Ga detectors, but exhibit responsivities a factor of 5 to 6 times higher when tested at a background photon flux of 10 8 photons/sec at lambda=93 μm. The introduction of Cu, a triple acceptor in Ge which acts as a neutral scattering center, reduces carrier mobility and extends the breakdown field significantly in this ultra-low compensation material

Phase change behaviors of Zn-doped Ge2Sb2Te5 films

International Nuclear Information System (INIS)

Wang Guoxiang; Nie Qiuhua; Shen Xiang; Fu Jing; Xu Tiefeng; Dai Shixun; Wang, R. P.; Wu Liangcai

2012-01-01

Zn-doped Ge 2 Sb 2 Te 5 phase-change materials have been investigated for phase change memory applications. Zn 15.16 (Ge 2 Sb 2 Te 5 ) 84.84 phase change film exhibits a higher crystallization temperature (∼258 °C), wider band gap (∼0.78 eV), better data retention of 10 years at 167.5 °C, higher crystalline resistance, and faster crystallization speed compared with the conventional Ge 2 Sb 2 Te 5 . The proper Zn atom added into Ge 2 Sb 2 Te 5 serves as a center for suppression of the face-centered-cubic (fcc) phase to hexagonal close-packed (hcp) phase transition, and fcc phase has high thermal stability partially due to the bond recombination among Zn, Sb, and Te atoms.

Radiochemical studies relevant to cyclotron production of the radionuclides 71,72As, 68Ge/68Ga and 76,77,80mBr

International Nuclear Information System (INIS)

Shehata, Mohamed Mostafa Mostafa

2011-01-01

The radionuclides 71,72,73,74 As, 68 Ge/ 68 Ga and 76,77,80m Br are gaining considerable interest in nuclear medicine. A method for the separation of no-carrier-added arsenic radionuclides from the bulk amount of proton-irradiated GeO 2 target as well as from coproduced radiogallium was developed. The extraction of radioarsenic by different organic solvents from acid solutions containing alkali iodide was studied and optimized. The influence of the concentration of various acids (HCl, HClO 4 , HNO 3 , HBr, H 2 SO 4 ) as well as of KI was studied using cyclohexane. The practical application of the optimized procedure in the production of 71 As and 72 As is demonstrated. The batch yields achieved were in the range of 75-84% of the theoretical values. The radiochemical separation of radiogallium from radiogermanium was studied using ion exchange chromatography (Amberlite IR-120) and solvent extraction (Aliquat 336 in o-xylene). At first optimized methods for the separation of no-carrier-added 68 Ge/ 69 Ge formed via the nat Ga(p,xn) 69 Ge process in a Ga 2 O 3 target and for n.c.a. 67 Ga formed via the nat Zn(p,xn) 67 Ga reaction in a Zn target were developed. Using those radionuclides as tracers several factors affecting the separation of radiogallium from radiogermanium were studied and for each procedure the optimum conditions were determined. The solvent extraction using Aliquat 336 was found to be more suitable and was adapted to the separation of n.c.a. 68 Ga from its parent n.c.a. 68 Ge. The quality of the product thus obtained is discussed. The separation of no-carrier-added radiobromine and no-carrier-added radiogallium from proton irradiated ZnSe target was studied in detail. The adsorption behaviour of n.c.a. radiobromine, n.c.a. radiogallium, zinc and selenium towards the cation-exchange resin Amberlyst 15, in H + form, and towards the anion-exchange resin Dowex 1X10 in Cl - and OH - forms, was investigated. The elution of n.c.a. radiobromine and n

Selective growth of Ge nanowires by low-temperature thermal evaporation.

Science.gov (United States)

Sutter, Eli; Ozturk, Birol; Sutter, Peter

2008-10-29

High-quality single-crystalline Ge nanowires with electrical properties comparable to those of bulk Ge have been synthesized by vapor-liquid-solid growth using Au growth seeds on SiO(2)/Si(100) substrates and evaporation from solid Ge powder in a low-temperature process at crucible temperatures down to 700 °C. High nanowire growth rates at these low source temperatures have been identified as being due to sublimation of GeO from substantial amounts of GeO(2) on the powder. The Ge nanowire synthesis from GeO is highly selective at our substrate temperatures (420-500 °C), i.e., occurs only on Au vapor-liquid-solid growth seeds. For growth of nanowires of 10-20 µm length on Au particles, an upper bound of 0.5 nm Ge deposition was determined in areas of bare SiO(2)/Si substrate without Au nanoparticles.

B-factory via conversion of 1-TeV electron beams into 1-TeV photon beams

International Nuclear Information System (INIS)

Mtingwa, S.K.

1991-01-01

This paper reports on the study of CP violation and rare decays of beauty particles which are pressing problems in high-energy physics. It is known that one should analyze beauty decays of at least the order of 10 8 or 19 9 . Thus, numerous proposals for beauty factories are being discussed now, although some of these projects are likely to supply much smaller numbers of beauty events. At the same time, at present several projects, such as CLIC (Cern Linear Collider), expect to build linear e + e - colliders with beam energies up to 1 TeV. The aim of this work is to show that the possibility exists of using the unique features of the discussed teraelectron volt electron linacs to obtain a facility for the production of beauty via photoproduction of nuclei. Unique features of high-energy photoproduction are as follows. The rather large fraction (∼2 x 10 -4 ) of events with beauty at E γ ∼ 1 TeV. Beauty particles are produced with about equally large momenta ∼0.05 E γ and at rather large transverse momenta p t ∼ m b . The following scheme can be envisioned. The 1-TeV electron beam is Compton scattered off a low-energy (∼ 1-eV) laser pulse. The laser photons are thus converted into a highly collimated beam of energy E γ ∼ E e , directed along the electron's original line of motion. Such schemes to produce high-energy photon beams have been discussed. These 1-TeV photons are subsequently scattered onto a nuclear target to produce b bar b pairs

Molecular beam epitaxial growth of oriented and uniform Ge{sub 2}Sb{sub 2}Te{sub 5} nanoparticles with compact dimensions

Energy Technology Data Exchange (ETDEWEB)

Zheng, Beining; Sun, Yu; Wu, Jie; Yuan, Long; Wu, Xiaofeng; Huang, Keke; Feng, Shouhua, E-mail: shfeng@jlu.edu.cn [Jilin University, State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry (China)

2017-02-15

The scaling-down of phase change memory cell is critical to achieve high-performance and high-density memory devices. Herein, we report that Ge{sub 2}Sb{sub 2}Te{sub 5} nanoparticles along the [1 1 1] direction were synthesized without templates or etching in a molecular beam epitaxy system. Under non-stoichiometric Ge:Sb:Te beam ratio condition, the growth of high-density Ge{sub 2}Sb{sub 2}Te{sub 5} nanoparticles was achieved by Zn-doping. The average diameter of the nanoparticles is 8 nm, and the full width at half maximum of the size distribution is 2.7 nm. Our results suggest that the size and shape modifications of Ge{sub 2}Sb{sub 2}Te{sub 5} nanoparticles could be induced by Zn-doping which influences the nucleation in the growth process. In addition, the bonding states of Zn and Te verified by X-ray photoelectron spectroscopy proved that Zn atoms located in the Ge{sub 2}Sb{sub 2}Te{sub 5} matrix. This approach exemplified here can be applied to the sub-20 nm phase change memory devices and may also be extendable to be served in the design and development of more materials with phase transitions.

Change in local atomic and chemical bonding structures of Ge2Sb2Te5 alloys by isothermal heat treatment

International Nuclear Information System (INIS)

Lim, Woo-Sik; Cho, Sung-June; Lee, Hyun-Yong

2008-01-01

In this work, we report evaluation of the atomic-scale phase transformation characteristics in one of the most comprehensively utilized phase change materials today, Ge 2 Sb 2 Te 5 thin film. The phase transformation of Ge 2 Sb 2 Te 5 thin film from amorphous to hexagonal structure via fcc structure was confirmed by XRD measurements. The approximate values of optical energy gap are 0.72 and 0.50 eV, with slopes (B 1/2 ) in the extended absorption region of 5.3 x 10 5 and 10 x 10 5 cm -1 ·eV -1 for the amorphous and fcc-crystalline structures, respectively. In addition, X-ray photoelectron spectroscopy analysis revealed strengthening of the Te-Te bond as well as weakening of the Ge-Te bond during the amorphous-to-crystalline transition. This trend was also observed in extended X-ray absorption fine structure analysis where the Ge metallic bond lengths in the amorphous, fcc, and hexagonal structures were 0.262, 0.280, and 0.290 nm

Microbial decontaminations of species by 10 MeV E- Beam

International Nuclear Information System (INIS)

Mehdizadeh Shahi, A.; Fallahnejad, N.

2005-01-01

Spices are used significantly in food industries. These substances contain high microbial contamination that causes the spoilage of the products and it is also hazardous for the health of consumers. Irradiation is one of the most effective methods to decontaminate spices. In this research , the optimum dose of e-beams to reduce microbial contamination of spices is determined. Samples of spices such as: turmeric, black pepper, garlic powder, onion powder, oregano and spice, were packaged in 10 grams, and they were irradiated at the dose of 0-10 kGy by 10 MeV e-beams. After irradiation, the total microbial counts were determined by the pour plating method. The bacterial contamination of different spices was between 10 5 to 4.7 x 10 7 cfu/gr and the molds count was between 1.8x10 2 to 7.2 x 10 3 cfu/gr. The survival curve of the bacteria was drawn in terms of bio burden versus the radiation dose rates. By determining the D 10 value, the minimum dose for reducing the spices microbial contamination up to the optimum limit, were identified

Microstructures and thermoelectric properties of GeSbTe based layered compounds

Energy Technology Data Exchange (ETDEWEB)

Yan, F.; Zhu, T.J.; Zhao, X.B. [Zhejiang University, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Hangzhou (China); Dong, S.R. [Zhejiang University, Department of Information and Electronics Engineering, Hangzhou (China)

2007-08-15

Microstructures and thermoelectric properties of Ge{sub 1}Sb{sub 2}Te{sub 4} and Ge{sub 2}Sb{sub 2}Te{sub 5} chalcogenide semiconductors have been investigated to explore the possibility of their thermoelectric applications. The phase transformation from the face-centered cubic to hexagonal structure was observed in Ge{sub 2}Sb{sub 2}Te{sub 5} compounds prepared by the melt spinning technique. The Seebeck coefficient and electrical resistivity of the alloys were increased due to the enhanced scattering of charge carriers at grain boundaries. The maximum power factors of the rapidly solidified Ge{sub 1}Sb{sub 2}Te{sub 4} and Ge{sub 2}Sb{sub 2}Te{sub 5} attained 0.975 x 10{sup -3} Wm{sup -1}K{sup -2} at 750 K and 0.767 x 10{sup -3} Wm{sup -1}K{sup -2} at 643 K respectively, higher than those of water quenched counterparts, implying that thermoelectric properties of GeSbTe based layered compounds can be improved by grain refinement. The present results show this class of chalcogenide semiconductors is promising for thermoelectric applications. (orig.)

CuIn{sub x}Ga{sub 1-x}Se{sub 2} thin films prepared by electron beam evaporation

Energy Technology Data Exchange (ETDEWEB)

Venkatachalam, M.; Kannan, M.D.; Jayakumar, S.; Balasundaraprabhu, R.; Nandakumar, A.K. [Thin Film Center, Department of Physics, PSG College of Technology (India); Muthukumarasamy, N. [Department of Physics, Coimbatore Institute of Technology (India)

2008-05-15

CuIn{sub x}Ga{sub 1-x}Se{sub 2} bulk compound of three different compositions x=0.75, 0.80 and 0.85 have been prepared using individual elements of copper, indium, gallium and selenium. Thin films of CuIn{sub x}Ga{sub 1-x}Se{sub 2} have been deposited using the prepared bulk by electron beam evaporation method. The structural studies carried on the deposited films revealed that films annealed at 400 C are crystalline in nature exhibiting chalcopyrite phase. The position of the (1 1 2) peak in the X-ray diffractogram corresponding to the chalcopyrite phase has been found to be dependent on the percentage of gallium in the films. The composition of the prepared bulk and thin films has been identified using energy dispersive X-ray analysis. The photoluminescence spectra of the CuIn{sub x}Ga{sub 1-x}Se{sub 2} films exhibited sharp luminescence peaks corresponding to the band gap of the material. (author)

Examination of the temperature dependent electronic behavior of GeTe for switching applications

Energy Technology Data Exchange (ETDEWEB)

Champlain, James G.; Ruppalt, Laura B.; Guyette, Andrew C. [Naval Research Laboratory, Washington, DC 20375 (United States); El-Hinnawy, Nabil; Borodulin, Pavel; Jones, Evan; Young, Robert M.; Nichols, Doyle [Northrop Grumman Electronics Systems, Linthicum, Maryland 21090 (United States)

2016-06-28

The DC and RF electronic behaviors of GeTe-based phase change material switches as a function of temperature, from 25 K to 375 K, have been examined. In its polycrystalline (ON) state, GeTe behaved as a degenerate p-type semiconductor, exhibiting metal-like temperature dependence in the DC regime. This was consistent with the polycrystalline (ON) state RF performance of the switch, which exhibited low resistance S-parameter characteristics. In its amorphous (OFF) state, the GeTe presented significantly greater DC resistance that varied considerably with bias and temperature. At low biases (<1 V) and temperatures (<200 K), the amorphous GeTe low-field resistance dramatically increased, resulting in exceptionally high amorphous-polycrystalline (OFF-ON) resistance ratios, exceeding 10{sup 9} at cryogenic temperatures. At higher biases and temperatures, the amorphous GeTe exhibited nonlinear current-voltage characteristics that were best fit by a space-charge limited conduction model that incorporates the effect of a defect band. The observed conduction behavior suggests the presence of two regions of localized traps within the bandgap of the amorphous GeTe, located at approximately 0.26–0.27 eV and 0.56–0.57 eV from the valence band. Unlike the polycrystalline state, the high resistance DC behavior of amorphous GeTe does not translate to the RF switch performance; instead, a parasitic capacitance associated with the RF switch geometry dominates OFF state RF transmission.

Short and medium range structures of 80GeSe2–20Ga2Se3 chalcogenide glasses

Science.gov (United States)

Petracovschi, Elena; Calvez, Laurent; Cormier, Laurent; Le Coq, David; Du, Jincheng

2018-05-01

The short and medium range structures of 80GeSe2–20Ga2Se3 (or Ge23.5Ga11.8Se64.7) chalcogenide glasses have been studied by combining ab initio molecular dynamics (AIMD) simulations and experimental neutron diffraction studies. The structure factor and total correlation function were calculated from glass structures generated from AIMD simulations and compared with neutron diffraction experiments showing reasonable agreement. The atomic structures of ternary chalcogenide glasses were analyzed in detail, and it was found that gallium atoms are four-fold coordinated by selenium (Se) and form [GaSe4] tetrahedra. Germanium atoms on average also have four-fold coordination, among which Se is 3.5 with the remaining being Ge–Ge homo-nuclear bonds. Ga and Ge tetrahedra link together mainly through corner-sharing and some edge-sharing of Se. No homo-nuclear bonds were observed among Ga atoms or between Ge and Ga. In addition, Se–Se homo-nuclear bonds and Se chains with various lengths were observed. A small fraction of Se atom triclusters that bond to three cations of Ge and Ga were also observed, confirming earlier proposals from 77Se solid state nuclear magnetic resonance studies. Furthermore, the electronic structures of ternary chalcogenide glasses were studied in terms of atomic charge and electronic density of states in order to gain insights into the chemical bonding and electronic properties, as well as to provide an explanation of the observed atomic structures in these ternary chalcogenide glasses.

Structural study of Ge/GaAs thin films

International Nuclear Information System (INIS)

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

2012-01-01

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.

Can we push the fundamental Planck scale above $10^{19}$ GeV?

CERN Document Server

Stojkovic, Dejan

2014-01-01

The value of the quantum gravity scale is MPl = $10^{19}$ GeV. However, this is inherently a three-dimensional quantity. We know that we can bring this scale all the way down to TeV if we introduce extra dimensions with large volume. This will solve the hierarchy problem by destroying the desert between the electroweak and gravity scales, but will also introduce a host of new problems since some things (e.g. proton stability, neutrino masses etc) have their natural habitat in this desert. In contrast, we can also solve the hierarchy problem by reducing the number of dimensions at high energies. If the fundamental theory (which does not have to be gravity as we understand it today) is lower dimensional, then the fundamental energy scale might be much greater than 1019GeV. Then, some experimental and observational limits (e.g. on Lorentz invariance violation) which are coming close to or even exceeding the scale of 1019GeV can be evaded. In addition, scattering of particles at transplanckian energies will not p...

Ga–Ge–Te amorphous thin films fabricated by pulsed laser deposition

International Nuclear Information System (INIS)

Němec, P.; Nazabal, V.; Dussauze, M.; Ma, H.-L.; Bouyrie, Y.; Zhang, X.-H.

2013-01-01

UV pulsed laser deposition was employed for the fabrication of amorphous Ga–Ge–Te thin films. The local structure of the bulk glasses as well as corresponding thin films was studied using Raman scattering spectroscopy; the main structural motifs were found to be [GeTe 4 ], eventually [GaTe 4 ] corner-sharing tetrahedra and disordered Te chains. Optical functions of the films (refractive index, extinction coefficient) were characterized by variable angle spectroscopic ellipsometry. Photostability experiments showed all Ga–Ge–Te laser deposited films to be stable against 1550 nm laser irradiation in an as-deposited state. In an annealed state, the most photostable composition seems to be Ga 10 Ge 15 Te 75 . This particular composition was further studied from the point of view of thermal stability and stability against ageing in as-deposited state. - Highlights: ► Pulsed laser deposition was used for fabrication of amorphous Ga–Ge–Te thin films. ► GeTe 4 , eventually GaTe 4 tetrahedra and disordered Te chains form the film structure. ► Optical functions of Ge–Ga–Te films were characterized by spectroscopic ellipsometry. ► All as-deposited Ga–Ge–Te thin films are stable against 1550 nm irradiation. ► In annealed state, the most photostable composition seems to be Ga 10 Ge 15 Te 75

Physics of ep collisions in the TeV energy range

International Nuclear Information System (INIS)

Altarelli, G.; Mele, B.; Rueckl, R.

1984-01-01

We study the physics of electron-proton collisions in the range of centre-of-mass energies between √s approx.= 0.3 TeV (HERA) and √s approx.= (1-2) TeV. The latter energies would be achieved if the electron or positron beam of LEP [Esub(e) approx.= (50-100) GeV] is made to collide with the proton beam of LHC [Esub(p) approx.= (5-10) TeV]. (orig.)

Conventional 20-TeV, 10-Tesla, p/sup +-/ colliders

International Nuclear Information System (INIS)

Diebold, R.; Ankenbrandt, C.; Collins, T.

1982-01-01

The performance of various 20-TeV colliders is discussed assuming 10-Tesla bending magnets. For bunched beams, the luminosity for anti pp collisions will be approximately x 10 31 cm - 2 sec - 1 where is the average number of interactions per bunch collision desired by the experimenters; for pp collisions this becomes x 10 32 cm - 2 sec - 1 . Values of up to 25 can be accommodated in a straightforward manner. Continuous beam pp collisions may yield a luminosity of 10 33 to 10 34 cm - 2 sec - 1 if the large amount of energy in the intense beams can be handled. Assuming that adequate and reliable 10-Tesla magnets can be built without unforeseen difficulties, the construction cost of such a collider, together with its new laboratory in the desert, would cost 2 to 3 billion dollars (FY-82 dollars) using present-day, conventional techniques. Although such a machine appears straightforward to build, considerable R and D will be required in order to optimize the design and bring down costs

Epitaxial Fe3Si/Ge/Fe3Si thin film multilayers grown on GaAs(001)

International Nuclear Information System (INIS)

Jenichen, B.; Herfort, J.; Jahn, U.; Trampert, A.; Riechert, H.

2014-01-01

We demonstrate Fe 3 Si/Ge/Fe 3 Si/GaAs(001) structures grown by molecular-beam epitaxy and characterized by transmission electron microscopy, electron backscattered diffraction, and X-ray diffraction. The bottom Fe 3 Si epitaxial film on GaAs is always single crystalline. The structural properties of the Ge film and the top Fe 3 Si layer depend on the substrate temperature during Ge deposition. Different orientation distributions of the grains in the Ge and the upper Fe 3 Si film were found. The low substrate temperature T s of 150 °C during Ge deposition ensures sharp interfaces, however, results in predominantly amorphous films. We find that the intermediate T s (225 °C) leads to a largely [111] oriented upper Fe 3 Si layer and polycrystal films. The high T s of 325 °C stabilizes the [001] oriented epitaxial layer structure, i.e., delivers smooth interfaces and single crystal films over as much as 80% of the surface area. - Highlights: • Fe 3 Si/Ge/Fe 3 Si/GaAs(001) structures are grown by MBE. • The bottom Fe 3 Si film is always single crystalline. • The properties of the Ge film depend on the substrate temperature during deposition. • Optimum growth conditions lead to almost perfect epitaxy of Ge on Fe 3 Si

ac conductivity and dielectric properties of amorphous Se80Te20-xGex chalcogenide glass film compositions

International Nuclear Information System (INIS)

Hegab, N.A.; Afifi, M.A.; Atyia, H.E.; Farid, A.S.

2009-01-01

Thin films of the prepared Se 80 Te 20-x Ge x (x = 5, 7 and 10 at.%) were prepared by thermal evaporation technique. X-ray diffraction patterns showed that the films were in amorphous state. The ac conductivity and dielectric properties of the investigated film compositions were studied in the frequency range 0.1-100 kHz and in temperature range (303-373 K). The experimental results indicated that the ac conductivity and the dielectric properties depended on the temperature and frequency. The ac conductivity is found to obey the ω s law, in accordance with the hopping model, s is found to be temperature dependent (s 1 and dielectric loss ε 2 were found to decrease with frequency and increase with temperature. The maximum barrier height W m , calculated from dielectric measurements according to Guintini equation, agrees with that proposed by the theory of hopping over potential barrier as suggested by Elliott in case of chalcogenide glasses. The density of localized states was estimated for the studied film compositions. The variation of the studied properties with Ge content was also investigated.

Evidence for spin to charge conversion in GeTe(111

Directory of Open Access Journals (Sweden)

C. Rinaldi

2016-03-01

Full Text Available GeTe has been predicted to be the father compound of a new class of multifunctional materials, ferroelectric Rashba semiconductors, displaying a coupling between spin-dependent k-splitting and ferroelectricity. In this paper, we report on epitaxial Fe/GeTe(111 heterostructures grown by molecular beam epitaxy. Spin-pumping experiments have been performed in a radio-frequency cavity by pumping a spin current from the Fe layer into GeTe at the Fe ferromagnetic resonance and detecting the transverse charge current originated in the slab due to spin-to-charge conversion. Preliminary experiments indicate that a clear spin to charge conversion exists, thus unveiling the potential of GeTe for spin-orbitronics.

Gravitino or axino dark matter with reheat temperature as high as 10{sup 16} GeV

Energy Technology Data Exchange (ETDEWEB)

Co, Raymond T. [Berkeley Center for Theoretical Physics, Department of Physics, University of California,366 LeConte Hall MC 7300, Berkeley, CA 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory,1 Cyclotron Rd., Berkeley, CA 94720 (United States); D’Eramo, Francesco [Department of Physics, University of California Santa Cruz,1156 High Street, Santa Cruz, CA 95064 (United States); Santa Cruz Institute for Particle Physics,1156 High Street, Santa Cruz, CA 95064 (United States); Hall, Lawrence J. [Berkeley Center for Theoretical Physics, Department of Physics, University of California,366 LeConte Hall MC 7300, Berkeley, CA 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory,1 Cyclotron Rd., Berkeley, CA 94720 (United States)

2017-03-01

A new scheme for lightest supersymmetric particle (LSP) dark matter is introduced and studied in theories of TeV supersymmetry with a QCD axion, a, and a high reheat temperature after inflation, T{sub R}. A large overproduction of axinos (ã) and gravitinos (G̃) from scattering at T{sub R}, and from freeze-in at the TeV scale, is diluted by the late decay of a saxion condensate that arises from inflation. The two lightest superpartners are ã, with mass of order the TeV scale, and G̃ with mass m{sub 3/2} anywhere between the keV and TeV scales, depending on the mediation scale of supersymmetry breaking. Dark matter contains both warm and cold components: for G̃ LSP the warm component arises from ã→G̃a, while for ã LSP the warm component arises from G̃→ãa. The free-streaming scale for the warm component is predicted to be of order 1 Mpc (and independent of m{sub 3/2} in the case of G̃ LSP). T{sub R} can be as high as 10{sup 16} GeV, for any value of m{sub 3/2}, solving the gravitino problem. The PQ symmetry breaking scale V{sub PQ} depends on T{sub R} and m{sub 3/2} and can be anywhere in the range (10{sup 10}−10{sup 16}) GeV. Detailed predictions are made for the lifetime of the neutralino LOSP decaying to ã+h/Z and G̃+h/Z/γ, which is in the range of (10{sup −1}−10{sup 6})m over much of parameter space. For an axion misalignment angle of order unity, the axion contribution to dark matter is sub-dominant, except when V{sub PQ} approaches 10{sup 16} GeV.

70Ge, 72Ge, 74Ge, 76Ge(d,3He)69Ga, 71Ga, 73Ga, 75Ga reactions at 26 MeV

International Nuclear Information System (INIS)

Rotbard, G.; La Rana, G.; Vergnes, M.; Berrier, G.; Kalifa, J.; Guilbaut, G.; Tamisier, R.

1978-01-01

The 70 Ge, 72 Ge, 74 Ge, 76 Ge(d, 3 He) 69 Ga, 71 Ga, 73 Ga, 75 Ga reactions have been studied at 26 MeV with 15 keV resolution (F.W.H.M), using the Orsay MP tandem accelerator and a split pole magnetic spectrometer. The spectroscopic factors are determined for 15 levels in 69 Ga and 11 levels in each of the 3 other Ga isotopes. Level schemes are proposed for the practically unknown 73 Ga and 75 Ga. Very simple model wave functions previously proposed for Ge nuclei are seen to reproduce quite well the measured occupation numbers for the proton orbitals. Anomalies in these occupation numbers are observed between Z=31 and 32 and between N=40 and 42, this last one corresponding to the structural transition observed recently in a comparison of the (p,t) and (t,p) reactions. These anomalies could be related to changes in the nuclear shape

Thermoelectric properties of c-GeSb{sub 0.75}Te{sub 0.5} to h-GeSbTe{sub 0.5} thin films through annealing treatment effects

Energy Technology Data Exchange (ETDEWEB)

Vora-ud, Athorn, E-mail: athornvora-ud@snru.ac.th [Program of Physics, Faculty of Science and Technology, Sakon Nakhon Rajabhat University, Mueang District, Sakon Nakhon 47000 (Thailand); Thermoelectrics Research Center, Research and Development Institution, Sakon Nakhon Rajabhat University, Mueang District, Sakon Nakhon 47000 (Thailand); Horprathum, Mati, E-mail: mati.horprathum@nectec.or.th [National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Eiamchai, Pitak [National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Muthitamongkol, Pennapa; Chayasombat, Bralee; Thanachayanont, Chanchana [National Metal and Materials Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Pankiew, Apirak [National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Klamchuen, Annop [National Nanotechnology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Naenkieng, Daengdech; Plirdpring, Theerayuth; Harnwunggmoung, Adul [Thermoelectric and Nanotechnology Research Center, Faculty of Science and Technology, Rajamangala University of Technology Suvarnabhumi, Huntra Phranakhon, Si Ayutthaya 13000 (Thailand); Charoenphakdee, Anek [NANO-Thermoelectrics Research Center, Division of Applied Physics, Faculty of Sciences and Liberal Arts, Rajamangala University of Technology Isan, Mueng Nakorn Ratchasima 30000 Thailand (Thailand); Somkhunthot, Weerasak [Program of Physics, Faculty of Science and Technology, Loei Rajabhat University, Muang District, Loei 42000 (Thailand); and others

2015-11-15

Germanium–Antimony–Tellurium (Ge–Sb–Te) thin films were deposited on silicon wafers with 1-μm silicon dioxide (SiO{sub 2}/Si) by pulsed dc magnetron sputtering from a 99.99% GeSbTe target of 1:1:1 ratio at ambient temperature. The samples were annealed at 573, 623, 673, and 723 K for 3600 s in a vacuum state. The effects of the annealing treatment on phase identification, atomic composition, morphology and film thickness, carrier concentration, mobility, and Seebeck coefficient of the Ge–Sb–Te samples have been investigated by grazing-incidence X-ray diffraction, auger electron spectroscopy, field-emission scanning electron microscopy, Hall-effect measurements, and steady state method, respectively. The results demonstrated that the as-deposited Ge–Sb–Te sample was amorphous. Atomic composition of as-deposited and annealed films at 573 K and 623 K were GeSb{sub 0.75}Te{sub 0.5} while annealed films at 673 K and 723 K were GeSbTe{sub 0.5} due to Sb-rich GeSb{sub 0.75}Te{sub 0.5}. The samples annealed at 573 K and 623 K showed the crystal phases of cubic structure (c-GeSb{sub 0.75}Te{sub 0.5}) into hexagonal structure (h-GeSbTe{sub 0.5}) after annealing at 673 K and 723 K. The study demonstrated the insulating condition from the as-deposited GeSbTe film, and the changes towards the thermoelectric properties from the annealing treatments. The GeSbTe films annealed at 673 K yielded excellent thermoelectric properties with the electrical resistivity, Seebeck coefficient, and power factor at approximately 1.45 × 10{sup −5} Ωm, 71.07 μV K{sup −1}, and 3.48 × 10{sup −4} W m{sup −1} K{sup −2}, respectively. - Highlights: • GeSbTe thin films were successfully sputtered for thermoelectric properties. • GeSbTe films were examined among physical, electrical and thermoelectric properties. • Thermoelectric properties were discussed based on composition of the films.

A comparative study of the electrical properties of Pd/ZnO Schottky contacts fabricated using electron beam deposition and resistive/thermal evaporation techniques

International Nuclear Information System (INIS)

Mtangi, W.; Auret, F. D.; Janse van Rensburg, P. J.; Coelho, S. M. M.; Legodi, M. J.; Nel, J. M.; Meyer, W. E.; Chawanda, A.

2011-01-01

A systematic investigation to check the quality of Pd Schottky contacts deposited on ZnO has been performed on electron beam (e-beam) deposited and resistively/thermally evaporated samples using current-voltage, IV, and conventional deep level transient spectroscopy (DLTS) measurements. Room temperature IV measurements reveal the dominance of pure thermionic emission on the resistively evaporated contacts, while the e-beam deposited contacts show the dominance of generation recombination at low voltages, -10 A at a reverse voltage of 1.0 V whereas the e-beam deposited contacts have reverse currents of the order of 10 -6 A at 1.0 V. Average ideality factors have been determined as (1.43 ± 0.01) and (1.66 ± 0.02) for the resistively evaporated contacts and e-beam deposited contacts, respectively. The IV barrier heights have been calculated as (0.721 ± 0.002) eV and (0.624 ± 0.005) eV for the resistively evaporated and e-beam deposited contacts, respectively. Conventional DLTS measurements reveal the presence of three prominent defects in both the resistive and e-beam contacts. Two extra peaks with energy levels of 0.60 and 0.81 eV below the conduction band minimum have been observed in the e-beam deposited contacts. These have been explained as contributing to the generation recombination current that dominates at low voltages and high leakage currents. Based on the reverse current at 1.0 V, the degree of rectification, the dominant current transport mechanism and the observed defects, we conclude that the resistive evaporation technique yields better quality Schottky contacts for use in solar cells and ultraviolet detectors compared to the e-beam deposition technique. The 0.60 eV has been identified as possibly related to the unoccupied level for the doubly charged oxygen vacancy, V o 2+ .

Vertical beam size measurement in the CESR-TA e{sup +}e{sup −} storage ring using x-rays from synchrotron radiation

Energy Technology Data Exchange (ETDEWEB)

Alexander, J.P.; Chatterjee, A.; Conolly, C.; Edwards, E.; Ehrlichman, M.P.; Fontes, E. [Cornell University, Ithaca, NY 14853 (United States); Heltsley, B.K., E-mail: bkh2@cornell.edu [Cornell University, Ithaca, NY 14853 (United States); Hopkins, W.; Lyndaker, A.; Peterson, D.P.; Rider, N.T.; Rubin, D.L.; Savino, J.; Seeley, R.; Shanks, J. [Cornell University, Ithaca, NY 14853 (United States); Flanagan, J.W. [High Energy Accelerator Research Organization (KEK), Tsukuba (Japan)

2014-06-01

We describe the construction and operation of an X-ray beam size monitor (xBSM), a device measuring e{sup +} and e{sup −} beam sizes in the CESR-TA storage ring using synchrotron radiation. The device can measure vertical beam sizes of 10–100μm on a turn-by-turn, bunch-by-bunch basis at e{sup ±} beam energies of ∼2GeV. At such beam energies the xBSM images X-rays of ϵ≈1–10keV (λ≈0.1–1nm) that emerge from a hard-bend magnet through a single- or multiple-slit (coded aperture) optical element onto an array of 32 InGaAs photodiodes with 50μm pitch. Beamlines and detectors are entirely in-vacuum, enabling single-shot beam size measurement down to below 0.1 mA (2.5×10{sup 9} particles) per bunch and inter-bunch spacing of as little as 4 ns. At E{sub b}=2.1GeV, systematic precision of ∼1μm is achieved for a beam size of ∼12μm; this is expected to scale as ∝1/σ{sub b} and ∝1/E{sub b}. Achieving this precision requires comprehensive alignment and calibration of the detector, optical elements, and X-ray beam. Data from the xBSM have been used to extract characteristics of beam oscillations on long and short timescales, and to make detailed studies of low-emittance tuning, intra-beam scattering, electron cloud effects, and multi-bunch instabilities.

Influence of the additive Ag for crystallization of amorphous Ge-Sb-Te thin films

Energy Technology Data Exchange (ETDEWEB)

Song, Ki-Ho; Kim, Sung-Won; Seo, Jae-Hee [Faculty of Applied Chemical Engineering, Chonnam National University, 300 Yongbong-dong, Kwangju 500-757 (Korea, Republic of); Lee, Hyun-Yong, E-mail: hyleee@chonnam.ac.k [Faculty of Applied Chemical Engineering, Chonnam National University, 300 Yongbong-dong, Kwangju 500-757 (Korea, Republic of)

2009-05-29

We have investigated the optical and amorphous-to-crystalline transition properties in four-types of chalcogenide thin films; Ge{sub 2}Sb{sub 2}Te{sub 5}, Ge{sub 8}Sb{sub 2}Te{sub 11}, Ag-Ge{sub 2}Sb{sub 2}Te{sub 5} and Ag-Ge{sub 8}Sb{sub 2}Te{sub 11}. Crystallization was caused by nano-pulse illumination ({lambda} = 658 nm) with power (P) of 1-17 mW and pulse duration (t) of 10-460 ns, and the morphologies of crystallized spots were observed by SEM and microscope. It was found that the crystallized spot nearby linearly increases in size with increasing the illuminating energy (E = P {center_dot} t) and eventually ablated out by over illumination. Changes in the optical transmittance of as-deposited and annealed films were measured using a UV-vis-IR spectrophotometer. In addition, a speed of amorphous-to-crystalline transition was evaluated by detecting the reflection response signals for the nano-pulse scanning. Conclusively, the Ge{sub 8}Sb{sub 2}Te{sub 11} film has a faster crystallization speed than the Ge{sub 2}Sb{sub 2}Te{sub 5} film despite its higher crystallization temperature. The crystallization speed was largely improved by adding Ag in Ge{sub 2}Sb{sub 2}Te{sub 5} film but not in Ge{sub 8}Sb{sub 2}Te{sub 11} film. To explain these results, we considered a heat confinement by electron hopping.

Shower development of particles with momenta from 1 to 10 GeV in the CALICE Scintillator-Tungsten HCAL

CERN Document Server

Adloff, C.; Chefdeville, M.; Drancourt, C.; Gaglione, R.; Geffroy, N.; Karyotakis, Y.; Koletsou, I.; Prast, J.; Vouters, G.; Repond, J.; Schlereth, J.; Smith, J; Xia, L.; Baldolemar, E.; Li, J.; Park, S.T.; Sosebee, M.; White, A.P.; Yu, J.; Eigen, G.; Thomson, M.A.; Ward, D.R.; Benchekroun, D.; Hoummada, A.; Khoulaki, Y.; Apostolakis, J.; Dannheim, D.; Dotti, A; Elsener, K.; Folger, G.; Grefe, C.; Ivantchenko, V.; Killenberg, M.; Klempt, W.; van der Kraaij, E.; Lam, C B; Linssen, L.; Lucaci-Timoce, A.-I.; Münnich, A.; Poss, S.; Ribon, A.; Sailer, A.; Schlatter, D.; Strube, J.; Uzhinskiy, V.; Carloganu, C.; Gay, P.; Manen, S.; Royer, L.; Tytgat, M; Zaganidis, N; Blazey, G C; Dyshkant, A; Lima, J G R; Zutshi, V; Hostachy, J-Y; Morin, L; Cornett, U.; David, D.; Ebrahimi, A.; Falley, G.; Feege, N.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Karstensen, S.; Krivan, F.; Krüger, K.; Lu, S.; Lutz, B.; Morozov, S.; Morgunov, V.; Neubüser, C.; Reinecke, M.; Sefkow, F.; Smirnov, P.; Terwort, M.; Garutti, E.; Laurien, S.; Marchesini, I.; Matysek, M.; Ramilli, M.; Briggl, K.; Eckert, P.; Harion, T.; Schultz-Coulon, H.-Ch.; Shen, W.; Stamen, R.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; Wilson, G.W.; Kawagoe, K.; Sudo, Y.; Yoshioka, T.; Dauncey, P.D.; Wing, M; Salvatore, F; Cortina Gil, E.; Mannai, S.; Baulieu, G.; Calabria, P.; Caponetto, L.; Combaret, C.; Della Negra, R.; Grenier, G.; Han, R.; Ianigro, J-C.; Kieffer, R.; Laktineh, I.; Lumb, N.; Mathez, H.; Mirabito, L.; Petrukhin, A.; Steen, A.; Tromeur, W.; Vander Donckt, M.; Zoccarato, Y.; Calvo Alamillo, E.; Fouz, M.-C.; Puerta-Pelayo, J.; Corriveau, F.; Bobchenko, B.; Chadeeva, M.; Danilov, M.; Epifantsev, A.; Markin, O.; Mizuk, R.; Novikov, E.; Popov, V; Rusinov, V.; Tarkovsky, E.; Kirikova, N.; Kozlov, V.; Smirnov, P; Soloviev, Y.; Besson, D.; Buzhan, P.; Ilyin, A.; Kantserov, V.; Kaplin, V.; Karakash, A; Popova, E.; Tikhomirov, V.; Kiesling, C.; Seidel, K.; Simon, F.; Soldner, C.; Szalay, M.; Tesar, M.; Weuste, L.; Amjad, M.S.; Bonis, J.; Callier, S; Conforti di Lorenzo, S.; Cornebise, P.; Doublet, Ph.; Dulucq, F.; Fleury, J.; Frisson, T.; van der Kolk, N.; Li, H.; Martin-Chassard, G.; Richard, F.; de la Taille, Ch.; Pöschl, R.; Raux, L.; Rouene, J.; Seguin-Moreau, N; Anduze, M.; Balagura, V.; Boudry, V.; Brient, J-C.; Cornat, R.; Frotin, M.; Gastaldi, F.; Guliyev, E.; Haddad, Y.; Magniette, F.; Musat, G.; Ruan, M.; Tran, T.H.; Videau, H.; Bulanek, B; Zacek, J.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Ruzicka, P.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; Belhorma, B.; Ghazlane, H.; Kotera, K.; Takeshita, T.; Uozumi, S.; Chang, S.; Khan, A.; Kim, D.H.; Kong, D.J.; Oh, Y.D.; Götze, M.; Sauer, J.; Weber, S.; Zeitnitz, C.

2014-01-10

Lepton colliders are considered as options to complement and to extend the physics programme at the Large Hadron Collider. The Compact Linear Collider (CLIC) is an $e^+e^-$ collider under development aiming at centre-of-mass energies of up to 3 TeV. For experiments at CLIC, a hadron sampling calorimeter with tungsten absorber is proposed. Such a calorimeter provides sufficient depth to contain high-energy showers, while allowing a compact size for the surrounding solenoid. A fine-grained calorimeter prototype with tungsten absorber plates and scintillator tiles read out by silicon photomultipliers was built and exposed to particle beams at CERN. Results obtained with electrons, pions and protons of momenta up to 10 GeV are presented in terms of energy resolution and shower shape studies. The results are compared with several GEANT4 simulation models in order to assess the reliability of the Monte Carlo predictions relevant for a future experiment at CLIC.

Effect of precursors stoichiometry on morphology, crystallinity and electrical properties of ZnTe epilayers grown on (100)GaAs by MOVPE

International Nuclear Information System (INIS)

Paiano, P.; Lovergine, N.; Mancini, A.M.; Prete, P.

2005-01-01

The effect of precursors vapour stoichiometry on the morphological, structural and electrical properties of nominally undoped ZnTe grown on (100)GaAs by metalorganic vapour phase epitaxy is reported. The epilayers were grown at 350 C using dimethylzinc (Me 2 Zn) and di-isopropyltelluride, varying their molar flow rate ratios (MFRs) between 0.17 and 3.10. Growth in nearly stoichiometric (MFR=1.03) conditions results in best surface morphology, while samples grown in Te-rich conditions (MFR>1.7) showed micron-size hollow defects (with surface densities up to ∝10 6 cm -2 ) elongated in one of the left angle 011 right angle in-plane directions. The defects are associated to a local structural disorder of the material, ascribed to the formation of a Ga 2 Te 3 extrinsic phase at the ZnTe/GaAs interface. Ohmic contacts to p -ZnTe epilayers were prepared by tungsten evaporation and annealing at 350 C. The RT hole concentration in the epilayers varies almost linearly with Me 2 Zn molar flow between 2 x 10 15 cm -3 and 5 x 10 16 cm -3 . Temperature-dependent Hall measurements performed on samples grown at MFR≤1.03 demonstrate that the material p-type conductivity originates from a single acceptor centre with an ionisation energy between 94.7 meV and 118 meV, its concentration being in the 10 16 cm -3 range and slowly increasing with Me 2 Zn flow. We ascribe this acceptor to a complex formed by a substitutional carbon atom on a Te site and a donor on a nearest neighbor site (C Te -D Zn ), the donor impurity being further identified as Ga diffusing from the substrate. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

5-10 GeV neutrinos from gamma-Ray burst fireballs

Science.gov (United States)

Bahcall; Meszaros

2000-08-14

A gamma-ray burst fireball is likely to contain an admixture of neutrons. Inelastic collisions between differentially streaming protons and neutrons in the fireball produce nu(&mgr;) (nu;(&mgr;)) of approximately 10 GeV as well as nu(e) (nu;(e)) of approximately 5 GeV, which could produce approximately 7 events/year in km(3) detectors, if the neutron abundance is comparable to that of protons. Photons of approximately 10 GeV from pi(0) decay and approximately 100 MeV nu;(e) from neutron decay are also produced, but will be difficult to detect. Photons with energies less, similar1 MeV from shocks following neutron decay produce a characteristic signal which may be distinguishable from the proton-related MeV photons.

Development of 68Ge/68Ga Generator using 30 MeV Cyclotron

International Nuclear Information System (INIS)

Goo, Hur Min; Dae, Yang Seung; Hoon, Park Jeong; Dae, Park Yong; Je, Lee Eun; Bae, Kong Young; Kim, In Jong; Lee, Jin Woo; Hyun, Yu Kook

2012-05-01

The purpose of this research is to develop the 68 Ge/ 68 Ga generator where daughter nuclide 68 Ga can be eluted according to the designated periods from the resin which holds mother nuclide 68 Ge absorbed and to develop the 68 Ga utilization technology. 1. Target development for 68 Ge target and production of 68 Ge - Target designed for 68 Ge production with 30 MeV cyclotron - Target body material evaluation and proton beam irradiation 2. Separation of 68 Ge and development of column material and extraction system for 68 Ge/ 68 Ga separation - Development of 68 Ge separation method from nat Ga target - Development of absorbents for generator using stable isotope 3. Development of 68 Ga labelled radiopharmaceutical - Development of 68 Ga labelled benzamide derivative for diagnosis of melanoma - Development of 68 Ga dendrimer complex using nano-technology 4. Development of shield case for 68 Ge/ 68 Ga generator

Organometallic chemical vapor deposition and characterization of ZnGe(1-x)Si(x)P2-Ge alloys on GaP substrates

Science.gov (United States)

Xing, G. C.; Bachmann, Klaus J.; Posthill, J. B.; Timmons, M. L.

1993-01-01

The epitaxial growth of ZnGe(1-x)Si(x)P2-Ge alloys on GaP substrates by open tube organometallic chemical vapor deposition (OMCVD) is reported. The chemical composition of the alloys characterized by energy dispersive X-ray spectroscopy shows that alloys with x up to 0.13 can be deposited on (001) GaP. Epitaxial growth with mirror smooth surface morphology was achieved for x less than or equal to 0.05. Transmission electron microscopy (TEM) micrographs of these alloys show specular epitaxy and the absence of microstructural defects indicating a defect density of less than 10(exp 7) cm(sup -2). Selected area electron diffraction pattern of the alloy shows that the epitaxial layer crystallizes in the chalcopyrite structure with relatively weak superlattice reflections indicating certain degree of randomness in the cation sublattice. Hall measurements show that the alloys are p-type, like the unalloyed films; the carrier concentration, however, dropped about 10 times from 2 x 10(exp 18) to 2 x 10(exp 17) cm(sup -3). Absorption measurements indicate that the band tailing in the absorption spectra of the alloy was shifted about 0.04 eV towards shorter wavelength as compared to the unalloyed material. Diodes fabricated from the n(+)-GaP/p-ZnSiP2-ZnGeP2-Ge heterostructure at x = 0.05 have a reverse break-down voltage of -10.8 V and a reverse saturation current density of approximately 6 x 10(exp -8) A/sq cm.

Characterization of Ge Doping on Sb_2Te_3 for High-Speed Phase Change Memory Application

International Nuclear Information System (INIS)

Zhu Yue-Qin; Xie Hua-Qing; Zhang Zhong-Hua; Song San-Nian; Song Zhi-Tang; Shen Lan-Lan; Li Le; Wu Liang-Cai; Liu Bo

2015-01-01

The phase change material of Ge-doped Sb_2Te_3 is shown to have higher crystallization temperature and better thermal stability compared with pure Sb_2Te_3. Ge_0_._1_1Sb_2Te_3 alloys are considered to be a potential candidate for phase change random access memories, as proved by a higher crystallization temperature, a better data retention ability, and a faster switching speed in comparison with those of Ge_2Sb_2Te_5. In addition, Ge_0_._1_1Sb_2Te_3 presents extremely rapid reverse switching speed (10 ns), and up to 10"5 programming cycles are obtained with stable set and reset resistances. (paper)

Structural and electric properties of AgGaTe{sub 2} layers prepared using mixed source of Ag{sub 2}Te and Ga{sub 2}Te{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Uruno, Aya [Department of Electrical Engineering and Bioscience, Waseda University, Tokyo (Japan); Kobayashi, Masakazu [Department of Electrical Engineering and Bioscience, Waseda University, Tokyo (Japan); Kagami Memorial Research Institute for Materials Science and Technology, Waseda University, Tokyo (Japan)

2017-01-15

AgGaTe{sub 2} layers were prepared on Si substrates by a closed space sublimation method using a mixed powder source of Ag{sub 2}Te and Ga{sub 2}Te{sub 3}. Ag{sub 2}Te buffer layer deposition was introduced to eliminate melt-back etching. The effect of the molar ratio of Ag{sub 2}Te and Ga{sub 2}Te{sub 3} in the mixed source on the crystallinity of the AgGaTe{sub 2} layer was investigated. The composition and the phase of the layer was found to change depending on the molar ratio in the deposits, which could be controlled by the source molar ratio along with the Ag{sub 2}Te buffer layer thickness. It was confirmed that (112) oriented uniform AgGaTe{sub 2} layer with an abrupt interface between AgGaTe{sub 2} and Si was formed after those parameters were tuned. The obtained layer exhibited the acceptor concentration of around 2.5 x 10{sup 16} cm{sup -3}. A solar cell was fabricated using the p-AgGaTe{sub 2}/n-Si heterojunction, and exhibited a conversion efficiency of 1.15%. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Precision Measurement of the (e++e-) Flux in Primary Cosmic Rays from 0.5 GeV to 1 TeV with the Alpha Magnetic Spectrometer on the International Space Station

Science.gov (United States)

Aguilar, M.; Aisa, D.; Alpat, B.; Alvino, A.; Ambrosi, G.; Andeen, K.; Arruda, L.; Attig, N.; Azzarello, P.; Bachlechner, A.; Barao, F.; Barrau, A.; Barrin, L.; Bartoloni, A.; Basara, L.; Battarbee, M.; Battiston, R.; Bazo, J.; Becker, U.; Behlmann, M.; Beischer, B.; Berdugo, J.; Bertucci, B.; Bigongiari, G.; Bindi, V.; Bizzaglia, S.; Bizzarri, M.; Boella, G.; de Boer, W.; Bollweg, K.; Bonnivard, V.; Borgia, B.; Borsini, S.; Boschini, M. J.; Bourquin, M.; Burger, J.; Cadoux, F.; Cai, X. D.; Capell, M.; Caroff, S.; Casaus, J.; Cascioli, V.; Castellini, G.; Cernuda, I.; Cervelli, F.; Chae, M. J.; Chang, Y. H.; Chen, A. I.; Chen, H.; Cheng, G. M.; Chen, H. S.; Cheng, L.; Chikanian, A.; Chou, H. Y.; Choumilov, E.; Choutko, V.; Chung, C. H.; Clark, C.; Clavero, R.; Coignet, G.; Consolandi, C.; Contin, A.; Corti, C.; Coste, B.; Crispoltoni, M.; Cui, Z.; Dai, M.; Delgado, C.; Della Torre, S.; Demirköz, M. B.; Derome, L.; Di Falco, S.; Di Masso, L.; Dimiccoli, F.; Díaz, C.; von Doetinchem, P.; Donnini, F.; Du, W. J.; Duranti, M.; D'Urso, D.; Eline, A.; Eppling, F. J.; Eronen, T.; Fan, Y. Y.; Farnesini, L.; Feng, J.; Fiandrini, E.; Fiasson, A.; Finch, E.; Fisher, P.; Galaktionov, Y.; Gallucci, G.; García, B.; García-López, R.; Gargiulo, C.; Gast, H.; Gebauer, I.; Gervasi, M.; Ghelfi, A.; Gillard, W.; Giovacchini, F.; Goglov, P.; Gong, J.; Goy, C.; Grabski, V.; Grandi, D.; Graziani, M.; Guandalini, C.; Guerri, I.; Guo, K. H.; Habiby, M.; Haino, S.; Han, K. C.; He, Z. H.; Heil, M.; Hoffman, J.; Hsieh, T. H.; Huang, Z. C.; Huh, C.; Incagli, M.; Ionica, M.; Jang, W. Y.; Jinchi, H.; Kanishev, K.; Kim, G. N.; Kim, K. S.; Kirn, Th.; Kossakowski, R.; Kounina, O.; Kounine, A.; Koutsenko, V.; Krafczyk, M. S.; Kunz, S.; La Vacca, G.; Laudi, E.; Laurenti, G.; Lazzizzera, I.; Lebedev, A.; Lee, H. T.; Lee, S. C.; Leluc, C.; Li, H. L.; Li, J. Q.; Li, Q.; Li, Q.; Li, T. X.; Li, W.; Li, Y.; Li, Z. H.; Li, Z. Y.; Lim, S.; Lin, C. H.; Lipari, P.; Lippert, T.; Liu, D.; Liu, H.; Lomtadze, T.; Lu, M. J.; Lu, Y. S.; Luebelsmeyer, K.; Luo, F.; Luo, J. Z.; Lv, S. S.; Majka, R.; Malinin, A.; Mañá, C.; Marín, J.; Martin, T.; Martínez, G.; Masi, N.; Maurin, D.; Menchaca-Rocha, A.; Meng, Q.; Mo, D. C.; Morescalchi, L.; Mott, P.; Müller, M.; Ni, J. Q.; Nikonov, N.; Nozzoli, F.; Nunes, P.; Obermeier, A.; Oliva, A.; Orcinha, M.; Palmonari, F.; Palomares, C.; Paniccia, M.; Papi, A.; Pauluzzi, M.; Pedreschi, E.; Pensotti, S.; Pereira, R.; Pilo, F.; Piluso, A.; Pizzolotto, C.; Plyaskin, V.; Pohl, M.; Poireau, V.; Postaci, E.; Putze, A.; Quadrani, L.; Qi, X. M.; Räihä, T.; Rancoita, P. G.; Rapin, D.; Ricol, J. S.; Rodríguez, I.; Rosier-Lees, S.; Rozhkov, A.; Rozza, D.; Sagdeev, R.; Sandweiss, J.; Saouter, P.; Sbarra, C.; Schael, S.; Schmidt, S. M.; Schuckardt, D.; Schulz von Dratzig, A.; Schwering, G.; Scolieri, G.; Seo, E. S.; Shan, B. S.; Shan, Y. H.; Shi, J. Y.; Shi, X. Y.; Shi, Y. M.; Siedenburg, T.; Son, D.; Spada, F.; Spinella, F.; Sun, W.; Sun, W. H.; Tacconi, M.; Tang, C. P.; Tang, X. W.; Tang, Z. C.; Tao, L.; Tescaro, D.; Ting, Samuel C. C.; Ting, S. M.; Tomassetti, N.; Torsti, J.; Türkoǧlu, C.; Urban, T.; Vagelli, V.; Valente, E.; Vannini, C.; Valtonen, E.; Vaurynovich, S.; Vecchi, M.; Velasco, M.; Vialle, J. P.; Wang, L. Q.; Wang, Q. L.; Wang, R. S.; Wang, X.; Wang, Z. X.; Weng, Z. L.; Whitman, K.; Wienkenhöver, J.; Wu, H.; Xia, X.; Xie, M.; Xie, S.; Xiong, R. Q.; Xin, G. M.; Xu, N. S.; Xu, W.; Yan, Q.; Yang, J.; Yang, M.; Ye, Q. H.; Yi, H.; Yu, Y. J.; Yu, Z. Q.; Zeissler, S.; Zhang, J. H.; Zhang, M. T.; Zhang, X. B.; Zhang, Z.; Zheng, Z. M.; Zhuang, H. L.; Zhukov, V.; Zichichi, A.; Zimmermann, N.; Zuccon, P.; Zurbach, C.; AMS Collaboration

2014-11-01

We present a measurement of the cosmic ray (e++e-) flux in the range 0.5 GeV to 1 TeV based on the analysis of 10.6 million (e++e-) events collected by AMS. The statistics and the resolution of AMS provide a precision measurement of the flux. The flux is smooth and reveals new and distinct information. Above 30.2 GeV, the flux can be described by a single power law with a spectral index γ =-3.170 ±0.008 (stat+syst)±0.008 (energy scale) .

Development of a nano-zirconia based {sup 68}Ge/{sup 68}Ga generator for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Chakravarty, Rubel [Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Shukla, Rakesh [Chemistry Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Ram, Ramu [Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Tyagi, Avesh Kumar [Chemistry Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Dash, Ashutosh, E-mail: adash@barc.gov.i [Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Venkatesh, Meera [Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)

2011-05-15

Introduction: Most of the commercially available {sup 68}Ge/{sup 68}Ga generator systems are not optimally designed for direct applications in a clinical context. We have developed a nano-zirconia based {sup 68}Ge/{sup 68}Ga generator system for accessing {sup 68}Ga amenable for the preparation of radiopharmaceuticals. Methods: Nano-zirconia was synthesized by the in situ reaction of zirconyl chloride with ammonium hydroxide in alkaline medium. The physical characteristics of the material were studied by various analytical techniques. A 740 MBq (20 mCi) {sup 68}Ge/{sup 68}Ga generator was developed using this sorbent and its performance was evaluated for a period of 1 year. The suitability of {sup 68}Ga for labeling biomolecules was ascertained by labeling DOTA-TATE with {sup 68}Ga. Results: The material synthesized was nanocrystalline with average particle size of {approx}7 nm, pore-size of {approx}4 A and a high surface area of 340{+-}10 m{sup 2} g{sup -1}. {sup 68}Ga could be regularly eluted from this generator in 0.01N HCl medium with an overall radiochemical yield >80% and with high radionuclidic (<10{sup -5}% of {sup 68}Ge impurity) and chemical purity (<0.1 ppm of Zr, Fe and Mn ions). The compatibility of the product for preparation of {sup 68}Ga-labeled DOTA-TATE under the optimized reaction conditions was found to be satisfactory in terms of high labeling yields (>99%). The generator gave a consistent performance with respect to the elution yield and purity of {sup 68}Ga over a period of 1 year. Conclusions: The feasibility of preparing an efficient {sup 68}Ge/{sup 68}Ga generator which can directly be used for biomedical applications has been demonstrated.

Study of current-voltage characteristics in PbTe(Ga) alloys at low temperatures

International Nuclear Information System (INIS)

Akimov, B.A.; Albul, A.V.; Bogdanov, E.V.

1992-01-01

Results of determining current-voltage characteristics in PbTe(Ga) monocrystals of n- and p-types of conductivity in strong electric fields E ≤ 2 x 10 3 V/Cm at 4.2-77 K are presented. It was established that at helium and nitrogen temperatures, the current-voltage characteristics of PbTe(Ga) alloys, high-ohmic state of which was realized in helium, differed qualitatively from ones, typical for unalloyed PbTe. The superlinear dependence, observed in the fields, beginning from E ≥ 1 V/cm, is explained in the framework of concepts of strong electric field effect on conductivity of impurity states

A machine learning method to separate cosmic ray electrons from protons from 10 to 100 GeV using DAMPE data

Science.gov (United States)

Zhao, Hao; Peng, Wen-Xi; Wang, Huan-Yu; Qiao, Rui; Guo, Dong-Ya; Xiao, Hong; Wang, Zhao-Min

2018-06-01

DArk Matter Particle Explorer (DAMPE) is a general purpose high energy cosmic ray and gamma ray observatory, aiming to detect high energy electrons and gammas in the energy range 5 GeV to 10 TeV and hundreds of TeV for nuclei. This paper provides a method using machine learning to identify electrons and separate them from gammas, protons, helium and heavy nuclei with the DAMPE data acquired from 2016 January 1 to 2017 June 30, in the energy range from 10 to 100 GeV.

Congruent evaporation temperature of GaAs(001) controlled by As flux

International Nuclear Information System (INIS)

Zhou, Z. Y.; Zheng, C. X.; Tang, W. X.; Jesson, D. E.; Tersoff, J.

2010-01-01

The congruent evaporation temperature T c is a fundamental surface characteristic of GaAs and similar compounds. Above T c the rate of As evaporation exceeds that of Ga during Langmuir (free) evaporation into a vacuum. However, during molecular beam epitaxy (MBE) there is generally an external As flux F incident on the surface. Here we show that this flux directly controls T c . We introduce a sensitive approach to measure T c based on Ga droplet stability, and determine the dependence of T c on F. This dependence is explained by a simple model for evaporation in the presence of external flux. The capability of manipulating T c via changing F offers a means of controlling congruent evaporation with relevance to MBE, surface preparation methods, and droplet epitaxy.

Precision Measurement of the ($e^+ + e^−$) Flux in Primary Cosmic Rays from 0.5 GeV to 1 TeV with the Alpha Magnetic Spectrometer on the International Space Station

CERN Document Server

Aguilar, M; Alpat, B; Alvino, A; Ambrosi, G; Andeen, K; Arruda, L; Attig, N; Azzarello, P; Bachlechner, A; Barao, F; Barrau, A; Barrin, L; Bartoloni, A; Basara, L; Battarbee, M; Battiston, R; Bazo, J; Becker, U; Behlmann, M; Beischer, B; Berdugo, J; Bertucci, B; Bigongiari, G; Bindi, V; Bizzaglia, S; Bizzarri, M; Boella, G; de Boer, W; Bollweg, K; Bonnivard, V; Borgia, B; Borsini, S; Boschini, M J; Bourquin, M; Burger, J; Cadoux, F; Cai, X D; Capell, M; Caroff, S; Casaus, J; Cascioli, V; Castellini, G; Cernuda, I; Cervelli, F; Chae, M J; Chang, Y H; Chen, A I; Chen, H; Cheng, G M; Chen, H S; Cheng, L; Chikanian, A; Chou, H Y; Choumilov, E; Choutko, V; Chung, C H; Clark, C; Clavero, R; Coignet, G; Consolandi, C; Contin, A; Corti, C; Coste, B; Crispoltoni, M; Cui, Z; Dai, M; Delgado, C; Della Torre, S; Demirköz, M B; Derome, L; Di Falco, S; Di Masso, L; Dimiccoli, F; Díaz, C; von Doetinchem, P; Donnini, F; Du, W J; Duranti, M; D’Urso, D; Eline, A; Eppling, F J; Eronen, T; Fan, Y Y; Farnesini, L; Feng, J; Fiandrini, E; Fiasson, A; Finch, E; Fisher, P; Galaktionov, Y; Gallucci, G; García, B; García-López, R; Gargiulo, C; Gast, H; Gebauer, I; Gervasi, M; Ghelfi, A; Gillard, W; Giovacchini, F; Goglov, P; Gong, J; Goy, C; Grabski, V; Grandi, D; Graziani, M; Guandalini, C; Guerri, I; Guo, K H; Habiby, M; Haino, S; Han, K C; He, Z H; Heil, M; Hoffman, J; Hsieh, T H; Huang, Z C; Huh, C; Incagli, M; Ionica, M; Jang, W Y; Jinchi, H; Kanishev, K; Kim, G N; Kim, K S; Kirn, Th; Kossakowski, R; Kounina, O; Kounine, A; Koutsenko, V; Krafczyk, M S; Kunz, S; La Vacca, G; Laudi, E; Laurenti, G; Lazzizzera, I; Lebedev, A; Lee, H T; Lee, S C; Leluc, C; Li, H L; Li, J Q; Li, Q; Li, Q; Li, T X; Li, W; Li, Y; Li, Z H; Li, Z Y; Lim, S; Lin, C H; Lipari, P; Lippert, T; Liu, D; Liu, H; Lomtadze, T; Lu, M J; Lu, Y S; Luebelsmeyer, K; Luo, F; Luo, J Z; Lv, S S; Majka, R; Malinin, A; Mañá, C; Marín, J; Martin, T; Martínez, G; Masi, N; Maurin, D; Menchaca-Rocha, A; Meng, Q; Mo, D C; Morescalchi, L; Mott, P; Müller, M; Ni, J Q; Nikonov, N; Nozzoli, F; Nunes, P; Obermeier, A; Oliva, A; Orcinha, M; Palmonari, F; Palomares, C; Paniccia, M; Papi, A; Pauluzzi, M; Pedreschi, E; Pensotti, S; Pereira, R; Pilo, F; Piluso, A; Pizzolotto, C; Plyaskin, V; Pohl, M; Poireau, V; Postaci, E; Putze, A; Quadrani, L; Qi, X M; Räihä, T; Rancoita, P G; Rapin, D; Ricol, J S; Rodríguez, I; Rosier-Lees, S; Rozhkov, A; Rozza, D; Sagdeev, R; Sandweiss, J; Saouter, P; Sbarra, C; Schael, S; Schmidt, S M; Schuckardt, D; Schulz von Dratzig, A; Schwering, G; Scolieri, G; Seo, E S; Shan, B S; Shan, Y H; Shi, J Y; Shi, X Y; Shi, Y M; Siedenburg, T; Son, D; Spada, F; Spinella, F; Sun, W; Sun, W H; Tacconi, M; Tang, C P; Tang, X W; Tang, Z C; Tao, L; Tescaro, D; Ting, Samuel C C; Ting, S M; Tomassetti, N; Torsti, J; Türkoğlu, C; Urban, T; Vagelli, V; Valente, E; Vannini, C; Valtonen, E; Vaurynovich, S; Vecchi, M; Velasco, M; Vialle, J P; Wang, L Q; Wang, Q L; Wang, R S; Wang, X; Wang, Z X; Weng, Z L; Whitman, K; Wienkenhöver, J; Wu, H; Xia, X; Xie, M; Xie, S; Xiong, R Q; Xin, G M; Xu, N S; Xu, W; Yan, Q; Yang, J; Yang, M; Ye, Q H; Yi, H; Yu, Y J; Yu, Z Q; Zeissler, S; Zhang, J H; Zhang, M T; Zhang, X B; Zhang, Z; Zheng, Z M; Zhuang, H L; Zhukov, V; Zichichi, A; Zimmermann, N; Zuccon, P; Zurbach, C

2014-01-01

We present a measurement of the cosmic ray ($e^+ + e^−$) flux in the range 0.5 GeV to 1 TeV based on the analysis of 10.6 million ($e^+ + e^−$) events collected by AMS. The statistics and the resolution of AMS provide a precision measurement of the flux. The flux is smooth and reveals new and distinct information. Above 30.2 GeV, the flux can be described by a single power law with a spectral index γ=−3.170±0.008(stat+syst)±0.008(energy scale).

Observation of an excess of νe, νe events in a beam dump experiment at 400 GeV

Directory of Open Access Journals (Sweden)

P. Alibran

1978-03-01

Full Text Available A beam dump experiment has been performed at CERN in Gargamelle using the neutrino facility to look for penetrating particles produced either directly in the beam interaction or by prompt decay of new particles. A total of 32 interactions with a visible energy greater than 10 GeV has been found, classified, aftercorrections, into 18 charged current νμ or νμ, 5.1 neutral current and 8.9 νe or νe charged current events. An excess of νe events remains after all subtractions from any established sources. Results are presented in terms of the product of the cross section and the leptonic decay branching ratio of the possible source.

Low temperature epitaxy of Ge-Sb-Te films on BaF{sub 2} (111) by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Thelander, E., E-mail: erik.thelander@iom-leipzig.de; Gerlach, J. W.; Ross, U.; Lotnyk, A.; Rauschenbach, B. [Leibniz-Institut für Oberflächenmodifizierung e.V., Leipzig 04318 (Germany)

2014-12-01

Pulsed laser deposition was employed to deposit epitaxial Ge{sub 2}Sb{sub 2}Te{sub 5}-layers on the (111) plane of BaF{sub 2} single crystal substrates. X-ray diffraction measurements show a process temperature window for epitaxial growth between 85 °C and 295 °C. No crystalline growth is observed for lower temperatures, whereas higher temperatures lead to strong desorption of the film constituents. The films are of hexagonal structure with lattice parameters consistent with existing models. X-ray pole figure measurements reveal that the films grow with one single out-of-plane crystal orientation, but rotational twin domains are present. The out-of-plane epitaxial relationship is determined to be Ge{sub 2}Sb{sub 2}Te{sub 5}(0001) || BaF{sub 2}(111), whereas the in-plane relationship is characterized by two directions, i.e., Ge{sub 2}Sb{sub 2}Te{sub 5} [-12-10] || BaF{sub 2}[1-10] and Ge{sub 2}Sb{sub 2}Te{sub 5}[1-210] || BaF{sub 2}[1-10]. Aberration-corrected high-resolution scanning transmission electron microscopy was used to resolve the local atomic structure and confirm the hexagonal structure of the films.

Deep level defects in Ge-doped (010) β-Ga2O3 layers grown by plasma-assisted molecular beam epitaxy

Science.gov (United States)

Farzana, Esmat; Ahmadi, Elaheh; Speck, James S.; Arehart, Aaron R.; Ringel, Steven A.

2018-04-01

Deep level defects were characterized in Ge-doped (010) β-Ga2O3 layers grown by plasma-assisted molecular beam epitaxy (PAMBE) using deep level optical spectroscopy (DLOS) and deep level transient (thermal) spectroscopy (DLTS) applied to Ni/β-Ga2O3:Ge (010) Schottky diodes that displayed Schottky barrier heights of 1.50 eV. DLOS revealed states at EC - 2.00 eV, EC - 3.25 eV, and EC - 4.37 eV with concentrations on the order of 1016 cm-3, and a lower concentration level at EC - 1.27 eV. In contrast to these states within the middle and lower parts of the bandgap probed by DLOS, DLTS measurements revealed much lower concentrations of states within the upper bandgap region at EC - 0.1 - 0.2 eV and EC - 0.98 eV. There was no evidence of the commonly observed trap state at ˜EC - 0.82 eV that has been reported to dominate the DLTS spectrum in substrate materials synthesized by melt-based growth methods such as edge defined film fed growth (EFG) and Czochralski methods [Zhang et al., Appl. Phys. Lett. 108, 052105 (2016) and Irmscher et al., J. Appl. Phys. 110, 063720 (2011)]. This strong sensitivity of defect incorporation on crystal growth method and conditions is unsurprising, which for PAMBE-grown β-Ga2O3:Ge manifests as a relatively "clean" upper part of the bandgap. However, the states at ˜EC - 0.98 eV, EC - 2.00 eV, and EC - 4.37 eV are reminiscent of similar findings from these earlier results on EFG-grown materials, suggesting that possible common sources might also be present irrespective of growth method.

ISABELLE: a 200 + 200 GeV colliding beam facility

International Nuclear Information System (INIS)

Courant, E.D.

1977-01-01

Plans are under way for the construction of a pair of intersecting storage rings providing for colliding beams of protons of energy at least 200 GeV. The rings (circumference 2.62 km) will contain superconducting magnets constructed with braided Nb--Ti filamentary wire, with a peak field of 4.0 T corresponding to an energy of 200 GeV. A current of 10 A of protons will be injected at 29 GeV from the existing AGS accelerator at Brookhaven, using the energy stacking technique similar to that employed at the CERN ISR; subsequently the stored beam will be accelerated gradually in the storage rings. Six intersection areas will be provided for experiments. They are designed to provide flexibility in beam characteristics for different experiments. The maximum luminosity at full energy is expected to be 1.0 x 10 33 cm -2 s -1 , at 29 GeV it will be approximately 10 32 cm -2 s -1 . Recent work with prototype magnets indicates that fields of 5.0 T can be produced. This has led to an alternative design of somewhat larger rings (circumference 3.77 km) that should be capable of providing colliding beams at 400 + 400 GeV

Precision Measurement of the (e^{+}+e^{-}) Flux in Primary Cosmic Rays from 0.5 GeV to 1 TeV with the Alpha Magnetic Spectrometer on the International Space Station.

Science.gov (United States)

Aguilar, M; Aisa, D; Alpat, B; Alvino, A; Ambrosi, G; Andeen, K; Arruda, L; Attig, N; Azzarello, P; Bachlechner, A; Barao, F; Barrau, A; Barrin, L; Bartoloni, A; Basara, L; Battarbee, M; Battiston, R; Bazo, J; Becker, U; Behlmann, M; Beischer, B; Berdugo, J; Bertucci, B; Bigongiari, G; Bindi, V; Bizzaglia, S; Bizzarri, M; Boella, G; de Boer, W; Bollweg, K; Bonnivard, V; Borgia, B; Borsini, S; Boschini, M J; Bourquin, M; Burger, J; Cadoux, F; Cai, X D; Capell, M; Caroff, S; Casaus, J; Cascioli, V; Castellini, G; Cernuda, I; Cervelli, F; Chae, M J; Chang, Y H; Chen, A I; Chen, H; Cheng, G M; Chen, H S; Cheng, L; Chikanian, A; Chou, H Y; Choumilov, E; Choutko, V; Chung, C H; Clark, C; Clavero, R; Coignet, G; Consolandi, C; Contin, A; Corti, C; Coste, B; Crispoltoni, M; Cui, Z; Dai, M; Delgado, C; Della Torre, S; Demirköz, M B; Derome, L; Di Falco, S; Di Masso, L; Dimiccoli, F; Díaz, C; von Doetinchem, P; Donnini, F; Du, W J; Duranti, M; D'Urso, D; Eline, A; Eppling, F J; Eronen, T; Fan, Y Y; Farnesini, L; Feng, J; Fiandrini, E; Fiasson, A; Finch, E; Fisher, P; Galaktionov, Y; Gallucci, G; García, B; García-López, R; Gargiulo, C; Gast, H; Gebauer, I; Gervasi, M; Ghelfi, A; Gillard, W; Giovacchini, F; Goglov, P; Gong, J; Goy, C; Grabski, V; Grandi, D; Graziani, M; Guandalini, C; Guerri, I; Guo, K H; Habiby, M; Haino, S; Han, K C; He, Z H; Heil, M; Hoffman, J; Hsieh, T H; Huang, Z C; Huh, C; Incagli, M; Ionica, M; Jang, W Y; Jinchi, H; Kanishev, K; Kim, G N; Kim, K S; Kirn, Th; Kossakowski, R; Kounina, O; Kounine, A; Koutsenko, V; Krafczyk, M S; Kunz, S; La Vacca, G; Laudi, E; Laurenti, G; Lazzizzera, I; Lebedev, A; Lee, H T; Lee, S C; Leluc, C; Li, H L; Li, J Q; Li, Q; Li, Q; Li, T X; Li, W; Li, Y; Li, Z H; Li, Z Y; Lim, S; Lin, C H; Lipari, P; Lippert, T; Liu, D; Liu, H; Lomtadze, T; Lu, M J; Lu, Y S; Luebelsmeyer, K; Luo, F; Luo, J Z; Lv, S S; Majka, R; Malinin, A; Mañá, C; Marín, J; Martin, T; Martínez, G; Masi, N; Maurin, D; Menchaca-Rocha, A; Meng, Q; Mo, D C; Morescalchi, L; Mott, P; Müller, M; Ni, J Q; Nikonov, N; Nozzoli, F; Nunes, P; Obermeier, A; Oliva, A; Orcinha, M; Palmonari, F; Palomares, C; Paniccia, M; Papi, A; Pauluzzi, M; Pedreschi, E; Pensotti, S; Pereira, R; Pilo, F; Piluso, A; Pizzolotto, C; Plyaskin, V; Pohl, M; Poireau, V; Postaci, E; Putze, A; Quadrani, L; Qi, X M; Räihä, T; Rancoita, P G; Rapin, D; Ricol, J S; Rodríguez, I; Rosier-Lees, S; Rozhkov, A; Rozza, D; Sagdeev, R; Sandweiss, J; Saouter, P; Sbarra, C; Schael, S; Schmidt, S M; Schuckardt, D; Schulz von Dratzig, A; Schwering, G; Scolieri, G; Seo, E S; Shan, B S; Shan, Y H; Shi, J Y; Shi, X Y; Shi, Y M; Siedenburg, T; Son, D; Spada, F; Spinella, F; Sun, W; Sun, W H; Tacconi, M; Tang, C P; Tang, X W; Tang, Z C; Tao, L; Tescaro, D; Ting, Samuel C C; Ting, S M; Tomassetti, N; Torsti, J; Türkoğlu, C; Urban, T; Vagelli, V; Valente, E; Vannini, C; Valtonen, E; Vaurynovich, S; Vecchi, M; Velasco, M; Vialle, J P; Wang, L Q; Wang, Q L; Wang, R S; Wang, X; Wang, Z X; Weng, Z L; Whitman, K; Wienkenhöver, J; Wu, H; Xia, X; Xie, M; Xie, S; Xiong, R Q; Xin, G M; Xu, N S; Xu, W; Yan, Q; Yang, J; Yang, M; Ye, Q H; Yi, H; Yu, Y J; Yu, Z Q; Zeissler, S; Zhang, J H; Zhang, M T; Zhang, X B; Zhang, Z; Zheng, Z M; Zhuang, H L; Zhukov, V; Zichichi, A; Zimmermann, N; Zuccon, P; Zurbach, C

2014-11-28

We present a measurement of the cosmic ray (e^{+}+e^{-}) flux in the range 0.5 GeV to 1 TeV based on the analysis of 10.6 million (e^{+}+e^{-}) events collected by AMS. The statistics and the resolution of AMS provide a precision measurement of the flux. The flux is smooth and reveals new and distinct information. Above 30.2 GeV, the flux can be described by a single power law with a spectral index γ=-3.170±0.008(stat+syst)±0.008(energy scale).

Effect of precursors stoichiometry on morphology, crystallinity and electrical properties of ZnTe epilayers grown on (100)GaAs by MOVPE

Energy Technology Data Exchange (ETDEWEB)

Paiano, P.; Lovergine, N.; Mancini, A.M. [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, Via Arnesano, I-73100 Lecce (Italy); Prete, P. [Istituto per la Microelettronica e Microsistemi del CNR, Sezione di Lecce, Via Arnesano, I-73100 Lecce (Italy)

2005-11-01

The effect of precursors vapour stoichiometry on the morphological, structural and electrical properties of nominally undoped ZnTe grown on (100)GaAs by metalorganic vapour phase epitaxy is reported. The epilayers were grown at 350 C using dimethylzinc (Me{sub 2}Zn) and di-isopropyltelluride, varying their molar flow rate ratios (MFRs) between 0.17 and 3.10. Growth in nearly stoichiometric (MFR=1.03) conditions results in best surface morphology, while samples grown in Te-rich conditions (MFR>1.7) showed micron-size hollow defects (with surface densities up to {proportional_to}10{sup 6} cm{sup -2}) elongated in one of the left angle 011 right angle in-plane directions. The defects are associated to a local structural disorder of the material, ascribed to the formation of a Ga{sub 2}Te{sub 3} extrinsic phase at the ZnTe/GaAs interface. Ohmic contacts to p -ZnTe epilayers were prepared by tungsten evaporation and annealing at 350 C. The RT hole concentration in the epilayers varies almost linearly with Me{sub 2}Zn molar flow between 2 x 10{sup 15} cm{sup -3} and 5 x 10{sup 16} cm{sup -3}. Temperature-dependent Hall measurements performed on samples grown at MFR{<=}1.03 demonstrate that the material p-type conductivity originates from a single acceptor centre with an ionisation energy between 94.7 meV and 118 meV, its concentration being in the 10{sup 16} cm{sup -3} range and slowly increasing with Me{sub 2}Zn flow. We ascribe this acceptor to a complex formed by a substitutional carbon atom on a Te site and a donor on a nearest neighbor site (C{sub Te}-D{sub Zn}), the donor impurity being further identified as Ga diffusing from the substrate. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

What can we learn from experiments with 10 GeV photons

International Nuclear Information System (INIS)

Laget, J.M.

1998-09-01

I review various opportunities to 'see' the mechanisms of confinement at work: Meson spectroscopy; Off Forward Parton Distributions in electroproduction of mesons; Gluonic content of hadronic matter in photoproduction of vector mesons; Valence quark wave functions in photoproduction of pseudo-scalar mesons and in Compton Scattering; Short range structure of nuclei in photoproduction of charm near threshold. An intense continuous beam of real photons, in the 10 GeV range, and of electrons, in the 30 GeV range, will allow to address most of these issues. (author)

Ge nitride formation in N-doped amorphous Ge2Sb2Te5

International Nuclear Information System (INIS)

Jung, M.-C.; Lee, Y. M.; Kim, H.-D.; Kim, M. G.; Shin, H. J.; Kim, K. H.; Song, S. A.; Jeong, H. S.; Ko, C. H.; Han, M.

2007-01-01

The chemical state of N in N-doped amorphous Ge 2 Sb 2 Te 5 (a-GST) samples with 0-14.3 N at. % doping concentrations was investigated by high-resolution x-ray photoelectron spectroscopy (HRXPS) and Ge K-edge x-ray absorption spectroscopy (XAS). HRXPS showed negligible change in the Te 4d and Sb 4d core-level spectra. In the Ge 3d core-level spectra, a Ge nitride (GeN x ) peak developed at the binding energy of 30.2 eV and increased in intensity as the N-doping concentration increased. Generation of GeN x was confirmed by the Ge K-edge absorption spectra. These results indicate that the N atoms bonded with the Ge atoms to form GeN x , rather than bonding with the Te or Sb atoms. It has been suggested that the formation of Ge nitride results in increased resistance and phase-change temperature

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

International Nuclear Information System (INIS)

Shimura, Y.; Takeuchi, S.; Nakatsuka, O.; Vincent, B.; Gencarelli, F.; Clarysse, T.; Vandervorst, W.; Caymax, M.; Loo, R.; Jensen, A.; Petersen, D.H.; Zaima, S.

2012-01-01

We have investigated the Ga and Sn content dependence of the crystallinity and electrical properties of Ga-doped Ge 1-x Sn 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 1-x Sn x layers. We achieved the growth of a fully strained Ge 0.922 Sn 0.078 layer on Ge with a Ga concentration of 5.5 × 10 19 /cm 3 without any dislocations and stacking faults. The resistivity of the Ga-doped Ge 1-x Sn 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 1-x Sn x epitaxial layers being induced by the introduction of Sn. As a result, we found that the resistivity for the Ge 0.950 Sn 0.050 layer annealed at 600°C for 1 min is 3.6 times less than that of the Ga-doped Ge/Ge sample. - Highlights: ► Heavy Ga-doping into fully strained GeSn layers without the introduction of dislocations ► The uniform Ga depth profile allowed the introduction of Sn ► The decrease in resistivity with an increase in the activation level of Ga was caused by the introduction of Sn

Behaviour of the ZEUS uranium-scintillator calorimeter for low-energetic particles with energies of 0.2 - 10.0 GeV

International Nuclear Information System (INIS)

Fuertjes, A.

1990-02-01

A prototype for the high-resolution calorimeter (FCAL) of the ZEUS detector was tested at a test beam of the CERN PS for beam momenta between 0.5 GeV/c and 10.0 GeV/c. The response of the calorimeter to low-energetic electrons, positrons, pions of both polarities, and protons should be studied. Additionally the effect of dead matter in front of the calorimeter was experimentally studied. Following results could be determined: Electrons and Positrons of equal energy produce comparable signals in the detector. Their response is in the considered momentum range with an accuracy of below 1% linear. The energy resolution of the calorimeter for electrons and positrons in the studied energy interval amounts to 17.5%√E. The response of the calorimeter to π + and π - is similar down to momenta of 0.5 GeV/c. The e/π ratio reaches the value 1.0 for energies above 2 GeV. For small incident energies e/mip=0.62 result. The energy resolution for pions amounts for energies above 2 GeV about 34%/√E. For smaller particle energies improvements can be observed. Protons show an identical behaviour as the pions, if the interesting quantities are considered in dependence on their kinetic energy. Dead matter in the front of the calorimeter influences the particle signals of low-energetic positrons and pions. The pulse-height spectra of electrons remain symmetric, but shift to small values. This behaviour could be confirmed by Monte-Carlo calculations. Pions show a distribution becoming with increasing matter density more asymmetric. At energies up to 2 GeV a significant effect mean values, energy resolution, and e/h ratio can be recognized. Above 2 GeV no important nuisance of the response to positrons and pions can yet be observed. (orig.) [de

Simultaneous ultra-long data retention and low power based on Ge10Sb90/SiO2 multilayer thin films

Science.gov (United States)

You, Haipeng; Hu, Yifeng; Zhu, Xiaoqin; Zou, Hua; Song, Sannian; Song, Zhitang

2018-02-01

In this article, Ge10Sb90/SiO2 multilayer thin films were prepared to improve thermal stability and data retention for phase change memory. Compared with Ge10Sb90 monolayer thin film, Ge10Sb90 (1 nm)/SiO2 (9 nm) multilayer thin film had higher crystallization temperature and resistance contrast between amorphous and crystalline states. Annealed Ge10Sb90 (1 nm)/SiO2 (9 nm) had uniform grain with the size of 15.71 nm. After annealing, the root-mean-square surface roughness for Ge10Sb90 (1 nm)/SiO2 (9 nm) thin film increased slightly from 0.45 to 0.53 nm. The amorphization time for Ge10Sb90 (1 nm)/SiO2 (9 nm) thin film (2.29 ns) is shorter than Ge2Sb2Te5 (3.56 ns). The threshold voltage of a cell based on Ge10Sb90 (1 nm)/SiO2 (9 nm) (3.57 V) was smaller than GST (4.18 V). The results indicated that Ge10Sb90/SiO2 was a promising phase change thin film with high thermal ability and low power consumption for phase change memory application.

76 FR 27282 - Airworthiness Directives; General Electric Company CF34-10E2A1; CF34-10E5, CF34-10E5A1; CF34-10E6...

Science.gov (United States)

2011-05-11

... methods: Federal eRulemaking Portal: Go to http://www.regulations.gov . Follow the instructions for... Investigation of a General Electric Company (GE) CF34-10E turbofan engine experiencing high fan frame vibrations... likely to exist or develop in other products of the same type design. Proposed AD Requirements This...

Multi-core events in cosmic-ray induced interactions with lead at around 10 TeV

International Nuclear Information System (INIS)

Amato, N.; Arata, N.

1989-01-01

The analysis is made on the cosmic-ray induced interactions with lead at around 10 TeV on the basis of emulsion chamber data at Chacaltaya. A special attention is paid to the events detected as multi-cores under the spatial resolution of a few tens of microns. The observation of six double-core events and two triple-core events with the average invariant mass of 1.8 GeV/c 2 leads to the estimation on production frequency of such multicores as about 5% at 10 TeV at the atmospheric depth 540 gr/cm 2 . (author)

Design and test of a 40-kV, 80-A, 10-msec, neutral-beam power supply series

International Nuclear Information System (INIS)

North, G.G.

1977-01-01

To meet neutral-beam source requirements, a combination series switch/regulator system has been developed that can provide up to 40-kV at 80A output for 10-ms from the continuously decaying voltage of a charged capacitor bank. The system uses 100% feedback control of a series hard tube regulator. This feedback regulator is able to maintain a 40-kV output level for 100% load variations while the source voltage for the capacitor bank is drained from an initial 55-kV down to as low as 43-kV during a 10-ms pulse. In addition to controlling the output voltage, the series regulator tube also serves the dual role of a disconnect or interrupt switch at the end of each pulse and during the frequent occurrence of a neutral-beam source fault. In the interrupt mode, complete disconnect is achieved in less than 2-μs after first observance of a fault condition; recovery times to normal operation of less than 10-μs after fault clearance can be attained if desired

Techniques for evaluation of E-beam evaporative processes

International Nuclear Information System (INIS)

Meier, T.C.; Nelson, C.M.

1996-01-01

High dynamic range video imaging of the molten pool surface has provided insight regarding process responses at the melt pool liquid-vapor interface. A water-cooled video camera provides continuous high resolution imaging of the pool surface from a low angle position within 20 cm of the liquid-vapor interface. From the vantage point, the e-beam footprint is clearly defined and melt pool free surface shape can be observed. Effects of changes in a beam footprint, power distribution, and sweep frequency on pool surface shape and stability of vaporization are immediately shown. Other events observed and recorded include: formation of the pool and dissipation of ''rafts'' on the pool surface during startup, behavior of feed material as it enters the pool, effects of feed configuration changes on mixing of feed entering the pool volume and behaviors of co-evaporated materials of different vapor pressures at the feed/pool boundary. When used in conjunction with laser vapor monitoring, correlation between pool surface phenomena and vaporizer performance has been identified. This video capability was used in verifying the titanium evaporation model results presented at this conference by confirming the calculated melt pool surface deformations caused by vapor pressure of the departing evaporant at the liquid-vapor interface

Techniques for evaluation of E-beam evaporative processes

Energy Technology Data Exchange (ETDEWEB)

Meier, T.C.; Nelson, C.M.

1996-10-01

High dynamic range video imaging of the molten pool surface has provided insight regarding process responses at the melt pool liquid-vapor interface. A water-cooled video camera provides continuous high resolution imaging of the pool surface from a low angle position within 20 cm of the liquid-vapor interface. From the vantage point, the e-beam footprint is clearly defined and melt pool free surface shape can be observed. Effects of changes in a beam footprint, power distribution, and sweep frequency on pool surface shape and stability of vaporization are immediately shown. Other events observed and recorded include: formation of the pool and dissipation of ``rafts`` on the pool surface during startup, behavior of feed material as it enters the pool, effects of feed configuration changes on mixing of feed entering the pool volume and behaviors of co-evaporated materials of different vapor pressures at the feed/pool boundary. When used in conjunction with laser vapor monitoring, correlation between pool surface phenomena and vaporizer performance has been identified. This video capability was used in verifying the titanium evaporation model results presented at this conference by confirming the calculated melt pool surface deformations caused by vapor pressure of the departing evaporant at the liquid-vapor interface.

Molecular beam epitaxy of iodine-doped CdTe and (CdMg)Te

Energy Technology Data Exchange (ETDEWEB)

Fischer, F.; Waag, A.; Litz, Th.; Scholl, S.; Schmitt, M.; Landwehr, G. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Bilger, G. (Zentrum fuer Sonnenenergie und Wasserstofforschung, Stuttgart (Germany))

1994-08-01

The n-type doping of CdTe and (CdMg)Te by the use of the solid dopant source material ZnI[sub 2] is reported. Doping levels as high as 7x10[sup 18] cm[sup -3] have been obtained in CdTe with carrier mobilities around 500 cm[sup 2]/V[center dot]s at room temperature. For a dopant incorporation higher than 1x10[sup 19] cm[sup -3] the free carrier concentration decreases, indicating the onset of a compensation mechanism, which is observed in the case of chlorine and bromine doping, too. Preliminary experiments show that with increasing Mg concentration the free carrier concentration decreases. Nevertheless, CdMgTe with a magnesium concentration x=0.37 (band gap 2.2 eV at room temperature) can be doped up to 2x10[sup 17] cm[sup -3]. The existence of deep donor levels in this CdTe based ternary is not supposed to be the only reason for the reduction of the free carrier concentration. For high Mg support during molecular beam epitaxial (MBE) growth of wide gap (CdMg)Te layers, the ZnI[sub 2] incorporation is reduced, leading to low doping levels, too

InGaP solar cell on Ge-on-Si virtual substrate for novel solar power conversion

Science.gov (United States)

Kim, T. W.; Albert, B. R.; Kimerling, L. C.; Michel, J.

2018-02-01

InGaP single-junction solar cells are grown on lattice-matched Ge-on-Si virtual substrates using metal-organic chemical vapor deposition. Optoelectronic simulation results indicate that the optimal collection length for InGaP single-junction solar cells with a carrier lifetime range of 2-5 ns is wider than approximately 1 μm. Electron beam-induced current measurements reveal that the threading dislocation density (TDD) of InGaP solar cells fabricated on Ge and Ge-on-Si substrates is in the range of 104-3 × 107 cm-2. We demonstrate that the open circuit voltage (Voc) of InGaP solar cells is not significantly influenced by TDDs less than 2 × 106 cm-2. Fabricated InGaP solar cells grown on a Ge-on-Si virtual substrate and a Ge substrate exhibit Voc in the range of 0.96 to 1.43 V under an equivalent illumination in the range of ˜0.5 Sun. The estimated efficiency of the InGaP solar cell fabricated on the Ge-on-Si virtual substrate (Ge substrate) at room temperature for the limited incident spectrum spanning the photon energy range of 1.9-2.4 eV varies from 16.6% to 34.3%.

Impact of N-plasma and Ga-irradiation on MoS2 layer in molecular beam epitaxy

KAUST Repository

Mishra, Pawan

2017-01-03

Recent interest in two-dimensional materials has resulted in ultra-thin devices based on the transfer of transition metal dichalcogenides (TMDs) onto other TMDs or III-nitride materials. In this investigation, we realized p-type monolayer (ML) MoS2, and intrinsic GaN/p-type MoS2 heterojunction by the GaN overgrowth on ML-MoS2/c-sapphire using the plasma-assisted molecular beam epitaxy. A systematic nitrogen plasma (N∗2N2*) and gallium (Ga) irradiation studies are employed to understand the individual effect on the doping levels of ML-MoS2, which is evaluated by micro-Raman and high-resolution X-Ray photoelectron spectroscopy (HRXPS) measurements. With both methods, p-type doping was attained and was verified by softening and strengthening of characteristics phonon modes E12gE2g1 and A1gA1g from Raman spectroscopy. With adequate N∗2N2*-irradiation (3 min), respective shift of 1.79 cm−1 for A1gA1g and 1.11 cm−1 for E12gE2g1 are obtained while short term Ga-irradiated (30 s) exhibits the shift of 1.51 cm−1 for A1gA1g and 0.93 cm−1 for E12gE2g1. Moreover, in HRXPS valence band spectra analysis, the position of valence band maximum measured with respect to the Fermi level is determined to evaluate the type of doping levels in ML-MoS2. The observed values of valance band maximum are reduced to 0.5, and 0.2 eV from the intrinsic value of ≈1.0 eV for N∗2N2*- and Ga-irradiated MoS2 layers, which confirms the p-type doping of ML-MoS2. Further p-type doping is verified by Hall effect measurements. Thus, by GaN overgrowth, we attained the building block of intrinsic GaN/p-type MoS2 heterojunction. Through this work, we have provided the platform for the realization of dissimilar heterostructure via monolithic approach.

Formation of scandium nitride (ScN) layer on gallium arsenide (GaAs) substrate using a combined technique of e-beam evaporator and ammonia annealing treatment

Energy Technology Data Exchange (ETDEWEB)

Yong Shee Meng, Alvin [Institute of Nano Optoelectronics Research and Technology (INOR), sains@usm, Persiaran Bukit Jambul, 11900 Bayan Lepas, Penang (Malaysia); Zainal, Norzaini, E-mail: norzaini@usm.my [Nano Optoelectronics Research and Laboratory, Universiti Sains Malaysia, sains@usm, Persiaran Bukit Jambul, 11900, Bayan Lepas, Penang (Malaysia); Hassan, Zainuriah; Ibrahim, Kamarulazizi [Institute of Nano Optoelectronics Research and Technology (INOR), sains@usm, Persiaran Bukit Jambul, 11900 Bayan Lepas, Penang (Malaysia)

2015-12-30

Graphical abstract: - Highlights: • Forming ScN layer using electron e-beam evaporator with successive NH{sub 3} annealing thermal has been successfully demonstrated. • NH{sub 3} annealing played the role in changing the grain structure of the ScN layer. • The existence of Sc−N bonds was confirmed by XPS measurement. • The 900 °C annealed ScN layer showed the best structural and optical characteristics. • ScN layer annealed at 980 °C exhibited poor structural and optical characteristics. - Abstract: A demonstration on a new technique of growing ScN using electron beam (e-beam) evaporator, coupled with successive ammonia (NH{sub 3}) annealing treatment is presented in this paper. The annealing temperature was varied at 750, 800, 850, 900 and 980 °C in order to obtain the best ScN layer. It was found that as the annealing temperature increased, the surface morphology of the ScN layer changed and ScN grains formed abundantly on the surface. The best surface of ScN layer was found in the 900 °C annealed sample. However, the roughness of the ScN increased with temperature. The photoluminescence (PL) peak of the near-to-band-edge (NBE) of ScN was observable in all samples and its intensity was the highest in the 900 °C annealed sample. Note that when the annealing treatment was conducted at 980 °C, the GaN PL peak is observable. Raman peaks of TO(X) of ScN were much evident at the annealing temperature above 900 °C. The formation of Sc−N bonds was confirmed by X-ray spectroscopy (XPS) measurement. In the end of this work, we propose that the formation of ScN using the above techniques was successful, with thermal annealing at the temperature of 900 °C.

Formation of scandium nitride (ScN) layer on gallium arsenide (GaAs) substrate using a combined technique of e-beam evaporator and ammonia annealing treatment

International Nuclear Information System (INIS)

Yong Shee Meng, Alvin; Zainal, Norzaini; Hassan, Zainuriah; Ibrahim, Kamarulazizi

2015-01-01

Graphical abstract: - Highlights: • Forming ScN layer using electron e-beam evaporator with successive NH_3 annealing thermal has been successfully demonstrated. • NH_3 annealing played the role in changing the grain structure of the ScN layer. • The existence of Sc−N bonds was confirmed by XPS measurement. • The 900 °C annealed ScN layer showed the best structural and optical characteristics. • ScN layer annealed at 980 °C exhibited poor structural and optical characteristics. - Abstract: A demonstration on a new technique of growing ScN using electron beam (e-beam) evaporator, coupled with successive ammonia (NH_3) annealing treatment is presented in this paper. The annealing temperature was varied at 750, 800, 850, 900 and 980 °C in order to obtain the best ScN layer. It was found that as the annealing temperature increased, the surface morphology of the ScN layer changed and ScN grains formed abundantly on the surface. The best surface of ScN layer was found in the 900 °C annealed sample. However, the roughness of the ScN increased with temperature. The photoluminescence (PL) peak of the near-to-band-edge (NBE) of ScN was observable in all samples and its intensity was the highest in the 900 °C annealed sample. Note that when the annealing treatment was conducted at 980 °C, the GaN PL peak is observable. Raman peaks of TO(X) of ScN were much evident at the annealing temperature above 900 °C. The formation of Sc−N bonds was confirmed by X-ray spectroscopy (XPS) measurement. In the end of this work, we propose that the formation of ScN using the above techniques was successful, with thermal annealing at the temperature of 900 °C.

Optical band gap of ZnO thin films deposited by electron beam evaporation

International Nuclear Information System (INIS)

Nadeem, M. Y.; Ali, S. L.; Wasiq, M. F.; Rana, A. M.

2006-01-01

Optical band gap of ZnO thin films deposited by electron beam evaporation at evaporation rates ranging 5 As/sup -1/ to 15 As /sup -1/ and thickness ranging 1000A to 3000A is presented. Deposited films were annealed at 573K for one and half hour. The variations in the optical band gap were observed and showed decreasing behavior from 3.15 eV, 3.05 eV, from 3.18 eV to 3.10 eV and from 3.19 eV to 3.18 eV for films with respective thickness 1000A, 2000 A, 3000 A on increasing the evaporation rate from 5 As/sup-1/ to As/sup -1/ by keeping thickness constant. (author)

MICRO-MATERIAL HANDLING EMPLOYING E-BEAM GENERATED TOPOGRAPHIES OF COPPER AND ALUMINIUM

Directory of Open Access Journals (Sweden)

S. Matope

2012-01-01

Full Text Available

ENGLISH ABSTRACT: This paper focuses on the employment of copper and aluminium in a micro-material handling system actuated by Van der Waals forces. Electron beam (e-beam evaporator deposited both materials on a silicon substrate at a rate of 0.6-1.2 Angstroms/second, vacuum pressure between 2x10-6 and 3x10-6mbar, and at a current less than 10mA. A Veeco NanoMan V Atomic Force Microscope with Nanoscope version 7.3 software was used to analyse the root mean square (rms surface roughnesses of the generated topographies. Rumpf-Rabinovich’s rms formula was used to determine the Van der Waals forces exerted by the surfaces. It was synthesised that an e-beam deposition of 7 minutes’ duration on both materials produced an optimum micro-material handling solution, with copper suitable for the pick-up position and aluminium for the placement position.

AFRIKAANSE OPSOMMING: Die fokus van die artikel is op die gebruik van koper en aluminium in ‘n mikromateriaalhanteringstelsel, aangedryf deur Van der Waalskragte. ‘n Elektronstraal-verdamper plaas albei materiale op ‘n silikonbasis teen ‘n tempo van 0.6-1.2 Angstrom/sekonde, vakuumdruk tussen 2x10-6 en 3x10-6mbar, en teen ‘n stroom van minder as 10mA. ‘n Veeco NanoMan V Atomic Force mikroskoop, met Nanoscope 7.3 program-matuur is gebruik om die wortel-gemiddelde-kwadraat (wgk oppervlak ruheid van die gegenereerde topografieë te analiseer. Rumpf-Rabinovich se wgk-formule is gebruik om die Van der Waalskrage wat deur die oppervlaktes uitgeoefen word te bepaal. Dit is vasgestel dat ‘n elektronstraalafsetting van 7 minute op albei materiale die optimale materiaalhanteringoplossing bied, met koper geskik vir die optelposisie en aluminium vir die plasingsposisie.

Study of dimuon pair production in e+ e- collisions from 196 - 202 GeV

CERN Document Server

Flacher, Henning

2000-01-01

In this thesis the electroweak process $e^{+} e^{-}$ --> $μ^{+} μ^{-}$ was studied and an inclusive and exclusive cross section were measured. Furthermore the forward-backward asymmetry Afb was determined from the exclusive event sample. The investigated data was recorded·with the detector ALEPH at centre-of-mass energies of 196, 200 and 202 GeV resulting in a total integrated luminosity of 208.1 pb-1. All the measured results are in good agreement with the Standard Model. From the measurements of total cross sections and angular distributions for all the two fermion processes at energies from 130 - 202 GeV limits on processes beyond the Standard Model were derived. For Contact Interactions they were found to be of the order of 10 TeV while for TeV-Scale Quantum Gravity a limit for the ultra-violet cut-off parameter of A::1 TeV could be derived.

Observation of an excess of nu$_{e}$, n$\\overline{u}_{e}$ events in a beam dump experiment at 400 GeV

CERN Document Server

Alibran, P; Arnold, R; Bartley, J H; Bellotti, E; Bertrand, D; Blaes, R; Blondel, A; Blum, D; Bolognese, T; Bonetti, S; Bonneaud, G R; Bourotte, J; Bullock, F W; Burmeister, H; Carnesecchi, G; Cavalli, D; Conforto, G; Degrange, B; Dewit, M; Erriquez, O; Escoubés, B; Fiorini, Ettore; Frodesen, A G; Gillespie, J; Haguenauer, Maurice; Heusse, P; Jacquet, F; Jones, T W; Lutz, A M; Matteuzzi, C; Morfín, J G; Muciaccia, M T; Musset, P; Natali, S; Nguyen-Khac, U; Nuzzo, S; Pascaud, C; Pattison, B; Paty, M; Petitjean, P; Price, M; Pullia, Antonio; Riester, J L; Rognebakke, A; Rollier, M; Romano, F; Sacton, J; Skjeggestad, O; Sleeman, J C; Van Doninck, W K; Vialle, J P; Weerts, H; Welch, L; Willutzky, M; Zanotti, L

1978-01-01

A beam dump experiment has been performed at CERN in Gargammelle using the neutrino facility to look for penetrating particles produced either directly in the beam interaction or by prompt decay of new particles. A total of 32 interactions with a visible energy greater than 10 GeV has been found, classified, after corrections, into 18 charged current nu /sub mu / or nu /sub mu /, 5.1 neutral current and 8.9 nu /sub e/ or nu /sub e/ charged current events. An excess of nu /sub e/ events remains after all subtractions from any established sources. Results are presented in terms of the product of the cross section and the leptonic decay branching ratio of the possible source. (11 refs).

Electrical switching phenomenon and memory effect in the semiconductor chalcogenide glass Ge0.10 As0.20 Te0.70

International Nuclear Information System (INIS)

Haro, M.; Marquez, E.; Villares, P.; Jimenez-Garay, R.

1987-01-01

Electrical switching phenomenon, as well as the memory effect in the semiconductor chalcogenide glass Ge 0.10 As 0.20 Te 0.70 has been studied. A device with a plano-punctual interelectrode configuration has been designed and built, so that the electrical stimuli may be applied correctly. This device permits adequate positioning of the upper electrode, as well as contact pressure regulation. The I-V characteristics in the OFF-state have been obtained, showing a marked non-linear character. Equally, a relation has been found between the threshold voltage and electrical resistance parameters, indicating that the electrical power giving rise to the phenomenon is constant. Finally, memory effects showing a sudden reduction in electrical resistance, as well as interelectrode filaments, have been observed. (author)

In situ X-ray diffraction study of crystallization process of GeSbTe thin films during heat treatment

International Nuclear Information System (INIS)

Kato, Naohiko; Konomi, Ichiro; Seno, Yoshiki; Motohiro, Tomoyoshi

2005-01-01

The crystallization processes of the Ge 2 Sb 2 Te 5 thin film used for PD and DVD-RAM were studied in its realistic optical disk film configurations for the first time by X-ray diffraction using an intense X-ray beam of a synchrotron orbital radiation facility (SPring-8) and in situ quick detection with a Position-Sensitive-Proportional-Counter. The dependence of the amorphous-to-fcc phase-change temperature T 1 on the rate of temperature elevation R et gave an activation energy E a : 0.93 eV much less than previously reported 2.2 eV obtained from a model sample 25-45 times thicker than in the real optical disks. The similar measurement on the Ge 4 Sb 1 Te 5 film whose large reflectance change attains the readability by CD-ROM drives gave E a : 1.13 eV with larger T 1 than Ge 2 Sb 2 Te 5 thin films at any R et implying a lower sensitivity in erasing as well as a better data stability of the phase-change disk

Characteristics of phase transition and separation in a In-Ge-Sb-Te system

Energy Technology Data Exchange (ETDEWEB)

Park, Sung Jin [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Jang, Moon Hyung [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Park, Seung-Jong [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Cho, Mann-Ho, E-mail: mh.cho@yonsei.ac.kr [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Ko, Dae-Hong [Department of Material Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

2012-10-01

Highlights: Black-Right-Pointing-Pointer InGeSbTe films were fabricated via co-deposition stoichiometric GST and IST targets. Black-Right-Pointing-Pointer As the amount of IST was increased in InGeSbTe, the value for V{sub th} and the phase transition temperature were increased. Black-Right-Pointing-Pointer The phase separation in InGeSbTe is caused by differences in the enthalpy change for formation and different atomic concentrations. - Abstract: In-doped GeSbTe films were deposited by ion beam sputtering deposition (IBSD) using Ge{sub 2}Sb{sub 2}Te{sub 5} (GST) and In{sub 3}Sb{sub 1}Te{sub 2} (IST) as targets. The phase change characteristics of the resulting films were then investigated by electrical measurements, including static testing, in situ 4-point R{sub s} measurements, X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The threshold voltage of the films increased, with increasing levels of IST. This phenomenon is consistent with the increased crystallization temperature in X-ray data and in situ 4-point R{sub s} data. In addition, in In{sub 28}Ge{sub 12}Sb{sub 26}Te{sub 34}, multiple V{sub th} values with a stepwise change are observed. The minimum time for the crystallization of InGeSbTe films was shorter than that for GST. X-ray data and Raman data for the crystalline structure show that phase separation to In{sub 2}Te{sub 3} occurred in all of the InGeSbTe samples after annealing at 350 Degree-Sign C. Moreover, in the case of InGeSbTe films with high concentrations of In (28 at.%), Sb phase separation was also observed. The observed phases indicate that the origin of the phase separation of InGeSbTe films is from the enthalpy change of formation and differences in Ge-Te, In-Te, Sb-Te, In-Sb and In-In bond energies.

Molecular beam epitaxial growth of Bi2Te3 and Sb2Te3 topological insulators on GaAs (111 substrates: a potential route to fabricate topological insulator p-n junction

Directory of Open Access Journals (Sweden)

Zhaoquan Zeng

2013-07-01

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

Preparation and characterization of co-evaporated Cu{sub 2}ZnGeSe{sub 4} thin films

Energy Technology Data Exchange (ETDEWEB)

Uday Bhaskar, P.; Suresh Babu, G.; Kishore Kumar, Y.B.; Sundara Raja, V., E-mail: sundararajav@rediffmail.com

2013-05-01

Cu{sub 2}ZnGeSe{sub 4} (CZGSe), a member of Cu{sub 2}–II–IV–VI{sub 4} family, is a promising material for solar cell absorber layer in thin film heterojunction solar cells like Cu{sub 2}ZnSnS{sub 4} and Cu{sub 2}ZnSnSe{sub 4} which have been explored in recent years as alternate to CuInGaSe{sub 2} solar cells. The effect of substrate temperature (523 K–723 K) on the growth of CZGSe films is investigated by studying their structural, morphological and optical properties. Raman spectroscopy studies have been done to identify the phases in addition to X-ray diffraction studies. CZGSe films deposited at different substrate temperatures and annealed at 723 K in selenium atmosphere are Cu-rich and Ge-poor and contained secondary phases Cu{sub (2−x)}Se and ZnSe. CZGSe films obtained by reducing the starting Cu mass by 10% were found to be single phase with stannite structure, the lattice parameters being a = 0.563 nm, c = 1.101 nm. The direct optical band gap of CZGSe films is found to be 1.63 eV which is close to ideal band gap of 1.50 eV for the highest photovoltaic conversion efficiency. The films are found to be p-type. - Highlights: • Synthesis of Cu{sub 2}ZnGeSe{sub 4} films for solar cell absorber layer • Effect of substrate temperature on the growth of co-evaporated Cu{sub 2}ZnGeSe{sub 4} films • X-ray diffraction, Raman and morphological studies of Cu{sub 2}ZnGeSe{sub 4} thin films.

Growth and characterization of CdTe absorbers on GaAs by MBE for high concentration PV solar cells

Energy Technology Data Exchange (ETDEWEB)

Ari, Ozan; Polat, Mustafa; Selamet, Yusuf [Department of Physics, Izmir Institute of Technology, Izmir 35430 (Turkey); Karakaya, Merve [Department of Material Science and Engineering, Izmir Institute of Technology, Izmir 35430 (Turkey)

2015-11-15

CdTe based II-VI absorbers are promising candidates for high concentration PV solar cells with an ideal band gap for AM1.5 solar radiation. In this study, we propose single crystal CdTe absorbers grown on GaAs substrates with a molecular beam epitaxy (MBE) which is a clean deposition technology. We show that high quality CdTe absorber layers can be grown with full width half maximum of X-ray diffraction rocking curves (XRD RC) as low as 227 arc-seconds with 0.5% thickness uniformity that a 2 μm layer is capable of absorbing 99% of AM1.5 solar radiation. Bandgap of the CdTe absorber is found as 1.483 eV from spetroscopic ellipsometry (SE) measurements. Also, high absorption coefficient is calculated from the results, which is ∝5 x 10{sup 5}cm{sup -1} in solar radiation spectrum. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Experimental studies of the acoustic detection of particle showers and neutrino physics beyond 10 TeV

International Nuclear Information System (INIS)

Sulak, L.R.

1977-01-01

The physics of deep inelastic scattering induced by atmospheric neutrinos of approximately 10 TeV energy is discussed. A 10 9 ton water detector at great depth in the ocean, utilizing acoustic signals from the secondary showers and muon, is investigated. Recent results from Brookhaven and Harvard on the sonic signature produced by particles in water are presented. This work suggests that the 10 9 ton detector is feasible, and that energy depositions in the laboratory as small as 10 GeV may eventually be observable by this technique

Structure and density for As23Se67Ge10 amorphous films

International Nuclear Information System (INIS)

Shchurova, T.N.; Savchenko, N.D.

1999-01-01

The effect of thermal annealing and argon laser irradiation on structure and volume for thin amorphous As 23 Se 67 Ge 10 films deposited by thermal evaporation has been investigated. The short-range structure for the annealed films has been found to be more ordered as compared to the irradiated films. The decrease in film volume under thermal annealing and its increase under laser irradiation have been shown. The changes in film volume have been discussed in the context of non-ergodic model for the amorphous state equilibrium taking into account forces acting from the substrate

Structural, electric and kinetic parameters of ternary alloys of GeSbTe

Energy Technology Data Exchange (ETDEWEB)

Morales-Sanchez, E. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Libramiento Norponiente 2000, Ap. Postal 13, Juriquilla, Queretaro, C. P. 76230, (Mexico)]. E-mail: m6007@ciateq.net.mx; Prokhorov, E.F. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Libramiento Norponiente 2000, Ap. Postal 13, Juriquilla, Queretaro, C. P. 76230, (Mexico); Gonzalez-Hernandez, J. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Libramiento Norponiente 2000, Ap. Postal 13, Juriquilla, Queretaro, C. P. 76230, (Mexico); Mendoza-Galvan, A. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Libramiento Norponiente 2000, Ap. Postal 13, Juriquilla, Queretaro, C. P. 76230, (Mexico)

2005-01-03

Thin amorphous films of GeSbTe have been widely employed in the technology used for phase change optical memory or compact disks. In this article, we report on measurements of resistance, transmittance, and X-ray diffraction in thin films with stoichiometric compositions of Ge{sub 1}Sb{sub 4}Te{sub 7}, Ge{sub 1}Sb{sub 2}Te{sub 4}, Ge{sub 2}Sb{sub 2}Te{sub 5}, and Ge{sub 4}Sb{sub 1}Te{sub 5.} The resistivity, lattice constant, and the temperature at which transformation from the amorphous phase to the cubic crystalline structure occurs were calculated for each stoichiometric composition, and the energy activation was determined, applying Kissinger's model. It was found that the Ge{sub 4}Sb{sub 1}Te{sub 5} composition has the highest crystallization temperature (425 K), the highest resistivity (0.178 {omega} cm), the greatest E{sub a} (3.09 eV), and the lowest lattice constant (a=5.975 A) in the cubic phase at 170 deg C.

Improvement of reliability and speed of phase change memory devices with N7.9(Ge46.9Bi7.2Te45.9) films

Science.gov (United States)

Park, J. H.; Kim, S.-W.; Kim, J. H.; Ko, D.-H.; Wu, Z.; Cho, S. L.; Ahn, D.; Ahn, D. H.; Lee, J. M.; Nam, S. W.

2015-08-01

In this study, we propose a nitrogen-incorporated GeBiTe ternary phase of N7.9(Ge46.9Bi7.2Te45.9) as a phase change material for reliable PCM (Phase Change Memory) with high speed operation. We found that the N7.9(Ge46.9Bi7.2Te45.9) film shows the resistance value of 40 kΩ after annealing at 440oC for 10 minutes, which is much higher than the value of 3.4 kΩ in the case of conventional N7.0(Ge22.0Sb22.0Te56.0) films. A set operation time of 14 nsec was achieved in the devices due to the increased probability of the nucleation by the addition of the elemental Bi. The long data retention time of 10 years at 85oC on the base of 1% failure was obtained as the result of higher activation energy of 2.52 eV for the crystallization compared to the case of N7.0(Ge22.0Sb22.0Te56.0) film, in which the activation energy is 2.1 eV. In addition, a reset current reduction of 27% and longer cycles of endurance as much as 2 order of magnitude compared to the case of N7.0(Ge22.0Sb22.0Te56.0) were observed at a set operation time of 14 nsec. Our results show that N7.9(Ge46.9Bi7.2Te45.9) is highly promising for use as a phase change material in reliable PCMs with high performance and also in forthcoming storage class memory applications, too.

Improvement of reliability and speed of phase change memory devices with N7.9(Ge46.9Bi7.2Te45.9 films

Directory of Open Access Journals (Sweden)

J. H. Park

2015-08-01

Full Text Available In this study, we propose a nitrogen-incorporated GeBiTe ternary phase of N7.9(Ge46.9Bi7.2Te45.9 as a phase change material for reliable PCM (Phase Change Memory with high speed operation. We found that the N7.9(Ge46.9Bi7.2Te45.9 film shows the resistance value of 40 kΩ after annealing at 440oC for 10 minutes, which is much higher than the value of 3.4 kΩ in the case of conventional N7.0(Ge22.0Sb22.0Te56.0 films. A set operation time of 14 nsec was achieved in the devices due to the increased probability of the nucleation by the addition of the elemental Bi. The long data retention time of 10 years at 85oC on the base of 1% failure was obtained as the result of higher activation energy of 2.52 eV for the crystallization compared to the case of N7.0(Ge22.0Sb22.0Te56.0 film, in which the activation energy is 2.1 eV. In addition, a reset current reduction of 27% and longer cycles of endurance as much as 2 order of magnitude compared to the case of N7.0(Ge22.0Sb22.0Te56.0 were observed at a set operation time of 14 nsec. Our results show that N7.9(Ge46.9Bi7.2Te45.9 is highly promising for use as a phase change material in reliable PCMs with high performance and also in forthcoming storage class memory applications, too.

Investigations of metal contacts to amorphous evaporated Ge films and amorphous sputtered Si films

International Nuclear Information System (INIS)

Hafiz, M.; Mgbenu, E.; Tove, P.A.; Norde, H.; Petersson, S.

1976-02-01

Amorphous Ge or Si films have been used as ohmic contacts to high-resistivity n-silicon radiation detectors. One interesting property of this contact is that it does not inject minority carriers even when the depletion region extends up to the contact thus generating an extracting field there. The function of this contact is not yet fully explored. One part problem is the role of the metal films used as external contacts to the amorphous film. In this report the function of different contacting metals, such as Au, Al, Cr are investigated by measuring the I-V-characteristics of sandwich structures with two metals on both sides of the amorphous evaporated (Ge) and sputtered (Si) film (of typical thickness 1000 A). It was found that while the symmetric structures Au-αGe-Au and Cr-αGe-Cr were low-resistive (leading to resistivity values of approximately 10 5 Ωcm for the αGe film), Al-αGe-Al structures showed much higher resistance and were also polarity dependent. The former feature was found also for unsymmetric structures, i.e. Cr-αGe-Au, Cr-αGe-Al. (Auth.)

Computational analysis of the maximum power point for GaAs sub-cells in InGaP/GaAs/Ge triple-junction space solar cells

International Nuclear Information System (INIS)

Cappelletti, M A; Cédola, A P; Peltzer y Blancá, E L

2014-01-01

The radiation resistance in InGaP/GaAs/Ge triple-junction solar cells is limited by that of the middle GaAs sub-cell. In this work, the electrical performance degradation of different GaAs sub-cells under 1 MeV electron irradiation at fluences below 4 × 10 15 cm −2 has been analyzed by means of a computer simulation. The numerical simulations have been carried out using the one-dimensional device modeling program PC1D. The effects of the base and emitter carrier concentrations of the p- and n-type GaAs structures on the maximum power point have been researched using a radiative recombination lifetime, a damage constant for the minority carrier lifetime and carrier removal rate models. An analytical model has been proposed, which is useful to either determine the maximum exposure time or select the appropriate device in order to ensure that the electrical parameters of different GaAs sub-cells will have a satisfactory response to radiation since they will be kept above 80% with respect to the non-irradiated values. (paper)

Characteristics of Al/p-AgGaTe2 polycrystalline thin film Schottky barrier diode

International Nuclear Information System (INIS)

Patel, S.S.; Patel, B.H.; Patel, T.S.

2008-01-01

An Al/p-AgGaTe 2 polycrystalline thin film schottky barrier diode have been prepared by flash-evaporation of p-AgGaTe 2 onto a pre-deposited film of aluminium. The current-voltage, capacitance-voltage and photoresponse of the diode have been investigated. The important physical parameter such as barrier height of the fabricated diode was derived from these measurements. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Polarized proton beam for eRHIC

Energy Technology Data Exchange (ETDEWEB)

Huang, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ptitsyn, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Roser, T. [Brookhaven National Lab. (BNL), Upton, NY (United States)

2015-05-03

RHIC has provided polarized proton collisions from 31 GeV to 255 GeV in the past decade. To preserve polarization through numerous depolarizing resonances through the whole accelerator chain, harmonic orbit correction, partial snakes, horizontal tune jump system and full snakes have been used. In addition, close attentions have been paid to betatron tune control, orbit control and beam line alignment. The polarization of 60% at 255 GeV has been delivered to experiments with 1.8×10¹¹ bunch intensity. For the eRHIC era, the beam brightness has to be maintained to reach the desired luminosity. Since we only have one hadron ring in the eRHIC era, existing spin rotator and snakes can be converted to six snake configuration for one hadron ring. With properly arranged six snakes, the polarization can be maintained at 70% at 250 GeV. This paper summarizes the effort and plan to reach high polarization with small emittance for eRHIC.

In situ X-ray diffraction study of crystallization process of GeSbTe thin films during heat treatment

Energy Technology Data Exchange (ETDEWEB)

Kato, Naohiko [Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan)]. E-mail: e0957@mosk.tytlabs.co.jp; Konomi, Ichiro [Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan); Seno, Yoshiki [Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan); Motohiro, Tomoyoshi [Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan)

2005-05-15

The crystallization processes of the Ge{sub 2}Sb{sub 2}Te{sub 5} thin film used for PD and DVD-RAM were studied in its realistic optical disk film configurations for the first time by X-ray diffraction using an intense X-ray beam of a synchrotron orbital radiation facility (SPring-8) and in situ quick detection with a Position-Sensitive-Proportional-Counter. The dependence of the amorphous-to-fcc phase-change temperature T{sub 1} on the rate of temperature elevation R{sub et} gave an activation energy E{sub a}: 0.93 eV much less than previously reported 2.2 eV obtained from a model sample 25-45 times thicker than in the real optical disks. The similar measurement on the Ge{sub 4}Sb{sub 1}Te{sub 5} film whose large reflectance change attains the readability by CD-ROM drives gave E{sub a}: 1.13 eV with larger T{sub 1} than Ge{sub 2}Sb{sub 2}Te{sub 5} thin films at any R{sub et} implying a lower sensitivity in erasing as well as a better data stability of the phase-change disk.

Combined e-beam lithography using different energies

Czech Academy of Sciences Publication Activity Database

Krátký, Stanislav; Kolařík, Vladimír; Horáček, Miroslav; Meluzín, Petr; Král, Stanislav

2017-01-01

Roč. 177, JUN (2017), s. 30-34 ISSN 0167-9317 R&D Projects: GA TA ČR TE01020233; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : grayscale e-beam lithography * mix and match process * absorbed energy density * resist sensitivity * micro-optical elements Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Nano-processes (applications on nano-scale) Impact factor: 1.806, year: 2016

Crystallization and memory programming characteristics of Ge-doped SbTe materials of varying Sb : Te ratio

International Nuclear Information System (INIS)

Jeong, Jeung-hyun; Lee, Hyun Seok; Lee, Suyoun; Lee, Taek Sung; Kim, Won Mok; Wu Zhe; Cheong, Byung-ki; Kim, Seul Cham; Oh, Kyu Hwan

2009-01-01

A phase change memory (PCM) utilizes resistivity changes accompanying fast transitions from an amorphous to a crystalline phase (SET) and vice versa (RESET). An investigation was made on the SET characteristics of PCM cells with Ge-doped SbTe (Ge-ST) materials of two different Sb : Te ratios (4.53 and 2.08). For the material of higher Sb : Te (4.53), a SET operation was completed within several tens of nanoseconds via nucleation-free crystallization whereas the material of lower Sb : Te (2.08) rendered a slower SET operation requiring several hundred nanoseconds for a nucleation-mediated crystallization. From measurements of nucleation and growth kinetics via laser-induced crystallization, the observed SET characteristics of the former case were found to derive from a growth time about 10 3 times shorter than the nucleation time and those of the latter from a much shorter nucleation time as well as a longer growth time than in the former case. The measured nucleation kinetics of the lower Sb : Te (2.08) material is unexpected from the existing data, which has led us to advance an interesting finding that there occurs a trend-reversing change in the nucleation kinetics of the Ge-ST materials around the eutectic composition (Sb : Te ∼2.6); nucleation is accelerated with the increase in the Sb : Te ratio above Sb : Te of 2.6, but with a decrease in the Sb : Te ratio below it.

2 TeV HEB beam abort at the SSCL

International Nuclear Information System (INIS)

Schailey, R.; Bull, J.; Clayton, T.; Kocur, P.; Mokhov, N.

1993-05-01

The High Energy Booster (HEB) of the Superconducting Super Collider Laboratory (SSCL) will require a full aperture beam abort over a dynamic energy range of 200 GeV to 2 TeV. Since the HEB is a bi-polar machine, both clockwise (CW) and the counter-clockwise (CCW) beam aborts are required. Also, the stored beam energy of 6.55 MJ in the superconducting HEB imposes upon the full aperture requirement. In this report, we describe the abort channels in the HEB utility straight sections, aperture restrictions, mechanical interferences and solutions, kicker misfires, and a 1 TeV beam absorber

2 TeV HEB beam abort at the SSCL

International Nuclear Information System (INIS)

Schailey, R.; Bull, J.; Clayton, T.; Kocur, P.; Mokhov, N.V.

1993-01-01

The High Energy Booster (HEB) of the Superconducting Super Collider Laboratory (SSCL) will require a full aperture beam abort over a dynamic energy range of 200 GeV to 2 TeV. Since the HEB is a bi-polar machine, both clockwise (CW) and counter-clockwise (CCW) beam aborts are required. Also, the stored beam energy of 6.55 MJ in the superconducting HEB imposes the full aperture requirement. In this report, the authors describe the abort channels in the HEB utility straight sections, aperture restrictions, mechanical interferences and solutions, kicker misfires, and a 2 TeV beam absorber

Single phase semipolar (11 anti 22) GaN on (10 anti 10) sapphire

Energy Technology Data Exchange (ETDEWEB)

Ploch, S.; Stellmach, J.; Schwaner, T.; Frentrup, M.; Wernicke, T.; Pristovsek, M.; Kneissl, M. [Institute of Solid States Physics, (Germany); Park, J.B.; Niermann, T.; Lehmann, M. [Institute of Optics and Atomic Physics, TU Berlin, Hardenbergstr. 36, 10623 Berlin (Germany)

2011-07-01

InGaN quantum well based light emitters grown on (0001) GaN suffer from poor quantum efficiencies with increasing indium mole fraction due to strong polarization fields along the polar crystal orientation. This effect can be greatly reduced by growing on semi- and non-polar GaN orientations. Semipolar (11 anti 22) GaN layers were deposited by metalorganic vapour phase epitaxy on (10 anti 10) sapphire. After sapphire substrate nitridation at 1000 C, a GaN nucleation layer was deposited at high temperature, followed by the deposition of 1.5 nm thick GaN buffer layers. The samples show predominantly (11 anti 22) orientation with a small fraction of (10 anti 13) oriented domains. With increasing nitridation layer thickness the (10 anti 13) phase is suppressed leading to a very smooth surface morphology (rms roughness < 4nm). PL measurements show dominant basel plane stacking fault (BSF) I{sub 1} luminescence without any other defects. Transmission electron microscopy measurements reveal a high BSF density. The FWHM of the X-ray diffraction rocking curve measurements of the (1122) reflection decreases to 1193 arcsec and 739 arcsec along [1 anti 100] and [11 anti 23] respectively with increasing nucleation temperature. Using high temperature nucleation smooth and homogeneous (11 anti 22) phase GaN layers have been obtained.

Nanoscale interfacial engineering to grow Ge on Si as virtual substrates and subsequent integration of GaAs

International Nuclear Information System (INIS)

Leonhardt, Darin; Sheng, Josephine; Cederberg, Jeffrey G.; Li Qiming; Carroll, Malcolm S.; Han, Sang M.

2010-01-01

We have demonstrated the scalability of a process previously dubbed as Ge 'touchdown' on Si to substantially reduce threading dislocations below 10 7 /cm 2 in a Ge film grown on a 2 inch-diameter chemically oxidized Si substrate. This study also elucidates the overall mechanism of the touchdown process. The 1.4 nm thick chemical oxide is first formed by immersing Si substrates in a solution of H 2 O 2 and H 2 SO 4 . Subsequent exposure to Ge flux creates 3 to 7 nm-diameter voids in the oxide at a density greater than 10 11 /cm 2 . Comparison of data taken from many previous studies and ours shows an exponential dependence between oxide thickness and inverse temperature of void formation. Additionally, exposure to a Ge or Si atom flux decreases the temperature at which voids begin to form in the oxide. These results strongly suggest that Ge actively participates in the reaction with SiO 2 in the void formation process. Once voids are created in the oxide under a Ge flux, Ge islands selectively nucleate within the void openings on the newly exposed Si. Island nucleation and growth then compete with the void growth reaction. At substrate temperatures between 823 and 1053 K, nanometer size Ge islands that nucleate within the voids continue to grow and coalesce into a continuous film over the remaining oxide. Coalescence of the Ge islands is believed to result in the creation of stacking faults in the Ge film at a density of 5 x 10 7 /cm 2 . Additionally, coalescence results in films of 3 μm thickness having a root-mean-square roughness of 8 to 10 nm. We have found that polishing the films with dilute H 2 O 2 results in roughness values below 0.5 nm. However, stacking faults originating at the Ge-SiO 2 interface and terminating at the Ge surface are polished at a slightly reduced rate, and show up as 1 to 2 nm raised lines on the polished Ge surface. These lines are then transferred into the subsequent growth morphology of GaAs deposited by metal-organic chemical vapor

Direct formation of thin films and epitaxial overlayers at low temperatures using a low-energy (10-500 eV) ion beam deposition system

International Nuclear Information System (INIS)

Zuhr, R.A.; Alton, G.D.; Appleton, B.R.; Herbots, N.; Noggle, T.S.; Pennycook, S.J.

1987-01-01

A low-energy ion beam deposition system has been developed at Oak Ridge National Laboratory and has been applied successfully to the growth of epitaxial films at low temperatures for a number of different elements. The deposition system utilizes the ion source and optics of a commercial ion implantation accelerator. The 35 keV mass- and energy-analyzed ion beam from the accelerator is decelerated in a four-element electrostatic lens assembly to energies between 10 and 500 eV for direct deposition onto a target under UHV conditions. Current densities on the order of 10 μA/cm 2 are achieved with good uniformity over a 1.4 cm diameter spot. The completed films are characterized by Rutherford backscattering, ion channeling, cross-section transmission electron microscopy, and x-ray diffraction. The effects of substrate temperature, ion energy, and substrate cleaning have been studied. Epitaxial overlayers which show good minimum yields by ion channeling (3 to 4%) have been produced at temperatures as low as 375 0 C for Si on Si(100) and 250 0 C for Ge on Ge(100) at growth rates that exceed the solid-phase epitaxy rates at these temperatures by more than an order of magnitude

The study of the ion beam induced swelling in crystalline germanium irradiated by a 30 keV Ga+ focused ion beam

International Nuclear Information System (INIS)

Rubanov, S.; Munroe, P.R.; Stevens-Kalceff, M.

2005-01-01

The effect of swelling of crystalline Ge irradiated at room temperature with 30 keV Ga + focused ion beam (FIB) was studied by means of in situ FIB imaging, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The swelling occurred in the surface region of amorphous damage layer which was formed during ion irradiation. The degree of swelling reaches values up to 10 times for an implantation dose of ∼10 17 ions/cm 2 . Cross-secitonal TEM examination showed that the swelling is due to formation of a porous layer with a honeycomb structure. (author). 8 refs., 4 figs

Ion beam induced epitaxy in Ge- and B- coimplanted silicon

International Nuclear Information System (INIS)

Hayashi, N.; Hasegawa, M.; Tanoue, H.; Takahashi, H.; Shimoyama, K.; Kuriyama, K.

1992-01-01

The epitaxial regrowth of amorphous surface layers in and Si substrate has been studied under irradiation with 400 keV Ar + ions at the temperature range from 300 to 435degC. The amorphous layers were obtained by Ge + implantation, followed by B + implantation. The ion beam assisted epitaxy was found to be sensitive to both the substrate orientation and the implanted Ge concentration, and the layer-by-layer epitaxial regrowth seemed to be precluded in Si layers with high doses of Ge implants, e.g., 2.5 x 10 15 ions/cm 2 . Electrical activation of implanted dopant B was also measured in the recrystallized Si layer. (author)

Observation of a resonance at 4.4 GeV and additional structure near 4.1 GeV in e+e- annihilation

International Nuclear Information System (INIS)

Siegrist, J.; Abrams, G.S.; Boyarski, A.M.; Breidenbach, M.; Bulos, F.; Chinowsky, W.; Feldman, G.J.; Friedberg, C.E.; Fryberger, D.; Goldhaber, G.; Hanson, G.; Hartill, D.L.; Jaros, J.; Jean-Marie, B.; Kadyk, J.A.; Larsen, R.R.; Luke, D.; Luth, V.; Lynch, H.L.; Madaras, R.; Morehouse, C.C.; Nguyen, H.K.; Paterson, J.M.; Perl, M.L.; Peruzzi, I.; Pierre, F.M.; Piccolo, M.; Pun, T.P.; Rapidis, P.; Richter, B.; Sadoulet, B.; Schwitters, R.F.; Tanenbaum, W.; Trilling, G.H.; Vannucci, F.; Whitaker, J.S.; Winkelman, F.C.; Wiss, J.E.

1976-01-01

We observe a resonancelike structure in the total cross section for hadron production by e + e - colliding beams at a mass of 4414 +- 7 MeV having a total width GAMMA = 33 +- 10 MeV. From the area under this resonance, we deduce the partial width to electron pairs to be GAMMA/sub ee/ = 440 +- 140 eV. Further structure of comparable width is present near 4.1 GeV

Substrate temperature dependence of ZnTe epilayers grown on GaAs(0 0 1) by molecular beam epitaxy

Science.gov (United States)

Zhao, Jie; Zeng, Yiping; Liu, Chao; Li, Yanbo

2010-04-01

ZnTe thin films have been grown on GaAs(0 0 1) substrates at different temperatures with constant Zn and Te beam equivalent pressures (BEPs) by molecular beam epitaxy (MBE). In situ reflection high-energy electron diffraction (RHEED) observation indicates that two-dimensional (2D) growth mode can be established after around one-minute three-dimensional (3D) nucleation by increasing the substrate temperature to 340 °C. We found that Zn desorption from the ZnTe surface is much greater than that of Te at higher temperatures, and estimated the Zn sticking coefficient by the evolution of growth rate. The Zn sticking coefficient decreases from 0.93 to 0.58 as the temperature is elevated from 320 to 400 °C. The ZnTe epilayer grown at 360 °C displays the narrowest full-width at half-maximum (FWHM) of 660 arcsec from (0 0 4) reflection in double-crystal X-ray rocking curve (DCXRC) measurements. The surface morphology of ZnTe epilayers is strongly dependent on the substrate temperature, and the root-mean-square (RMS) roughness diminishes drastically with the increase in temperature.

Polarized photons from a silicon crystal in a 31 GeV electron beam at the Serpukhov proton accelerator

International Nuclear Information System (INIS)

Frolov, A.M.; Maisheev, V.A.; Arakelyan, E.A.; Armaganyan, A.A.; Avakyan, R.O.; Bayatyan, G.L.; Grigoryan, N.K.; Kechechyan, A.O.; Knyazyan, S.G.; Margaryan, A.T.

1980-01-01

Tagged photons coherently emitted in a silicon crystal by the 31 GeV electron beam of intensity 4 x 10 4 ppp and beam pulse duration of up to 1.7 s have been obtained at the Serpukhov proton accelerator. The photon intensities were I approx. 10 -1 - 10 -2 γ/e - in five almost equal energy bins within the total range k = (8.2-24.2) GeV. The calculated linear polarizations were P approx. 50-20%, respectively. Narrow peaks in the radiation intensity were observed when varying the orientation of a silicon crystal which could not be explained. The method for the experimental alignment of a crystal in electron beams at the proton accelerator has been described. (orig.)

Optimization of Si–C reaction temperature and Ge thickness in C-mediated Ge dot formation

Energy Technology Data Exchange (ETDEWEB)

Satoh, Yuhki, E-mail: yu-ki@ecei.tohoku.ac.jp; Itoh, Yuhki; Kawashima, Tomoyuki; Washio, Katsuyoshi

2016-03-01

To form Ge dots on a Si substrate, the effect of thermal reaction temperature of sub-monolayer C with Si (100) was investigated and the deposited Ge thickness was optimized. The samples were prepared by solid-source molecular beam epitaxy with an electron-beam gun for C sublimation and a Knudsen cell for Ge evaporation. C of 0.25 ML was deposited on Si (100) at a substrate temperature of 200 °C, followed by a high-temperature treatment at the reaction temperature (T{sub R}) of 650–1000 °C to create Si–C bonds. Ge equivalent to 2 to 5 nm thick was subsequently deposited at 550 °C. Small and dense dots were obtained for T{sub R} = 750 °C but the dot density decreased and the dot diameter varied widely in the case of lower and higher T{sub R}. A dot density of about 2 × 10{sup 10} cm{sup −2} was achieved for Ge deposition equivalent to 3 to 5 nm thick and a standard deviation of dot diameter was the lowest of 10 nm for 5 nm thick Ge. These results mean that C-mediated Ge dot formation was strongly influenced not only by the c(4 × 4) reconstruction condition through the Si–C reaction but also the relationship between the Ge deposition thickness and the exposed Si (100)-(2 × 1) surface area. - Highlights: • The effect of Si–C reaction temperature on Ge dot formation was investigated. • Small and dense dots were obtained for T{sub R} = 750 °C. • The dot density of about 2 × 10{sup 10} cm{sup −2} was achieved for Ge = 3 to 5 nm. • The standard deviation of dot diameter was the lowest of 10 nm at Ge = 5 nm.

Niobium tunnel junction fabrication using e-gun evaporation and SNAP

Science.gov (United States)

Kortlandt, J.; van der Zant, H. S. J.; Schellingerhout, A. J. G.; Mooij, J. E.

1990-11-01

We have fabricated high quality small area Nb-Al-Al 2O 3-Nb junctions with SNAP, making use of e-beam evaporation in a 10 -5 Pa diffusion pumped vacuum system. Nominal dimensions of the junctions are 8x8, 4x4 and 2x2 μm 2. We obtain typical current densities of 5-6 × 10 +2A/cm 2 and (critical current) x (subgap resistance) products of 40 mV.

Density functional simulations of Sb-rich GeSbTe phase change alloys

International Nuclear Information System (INIS)

Gabardi, S; Bernasconi, M; Caravati, S; Parrinello, M

2012-01-01

We generated models of the amorphous phase of Sb-rich GeSbTe phase change alloys by quenching from the melt within density functional molecular dynamics. We considered the two compositions Ge 1 Sb 1 Te 1 and Ge 2 Sb 4 Te 5 . Comparison with previous results on the most studied Ge 2 Sb 2 Te 5 allowed us to draw some conclusions on the dependence of the structural properties of the amorphous phase on the alloy composition. Vibrational and electronic properties were also scrutinized. Phonons at high frequencies above 200 cm -1 are localized in tetrahedra around Ge atoms in Sb-rich compounds as well as in Ge 2 Sb 2 Te 5 . All compounds are semiconducting in the amorphous phase, with a band gap in the range 0.7-1.0 eV.

Density functional simulations of Sb-rich GeSbTe phase change alloys

Science.gov (United States)

Gabardi, S.; Caravati, S.; Bernasconi, M.; Parrinello, M.

2012-09-01

We generated models of the amorphous phase of Sb-rich GeSbTe phase change alloys by quenching from the melt within density functional molecular dynamics. We considered the two compositions Ge1Sb1Te1 and Ge2Sb4Te5. Comparison with previous results on the most studied Ge2Sb2Te5 allowed us to draw some conclusions on the dependence of the structural properties of the amorphous phase on the alloy composition. Vibrational and electronic properties were also scrutinized. Phonons at high frequencies above 200 cm-1 are localized in tetrahedra around Ge atoms in Sb-rich compounds as well as in Ge2Sb2Te5. All compounds are semiconducting in the amorphous phase, with a band gap in the range 0.7-1.0 eV.

Hyperthermal K--TeF6 molecular beam scattering

International Nuclear Information System (INIS)

Wagner, A.F.; Young, C.E.; Pobo, L.G.; Wexler, S.

1982-01-01

Angular distributions of K + product ions from collisions of a beam of hyperthermal K atoms with a cross beam of thermal TeF 6 molecules were determined at 13.7 and 23.7 eV (lab). The angular yields of K atom products from the same system were too low to permit measurement of angular distributions. From the integrated yields, the K + ion/K atom branching ratio was determined to be greater than 10 3 . In addition to the extremely large branching ratio, the differential cross sections exhibited several other unusual characteristics: (a) the lack of small angle scattering, corresponding to virtual absence of covalent scattering, (b) two peaks in the differential cross section with an outer rainbow feature at very large scattering angles (approx.275 eV deg). The observations are unexpected from previous experimental and theoretical studies of electron transfer reactions and from the electronic and structural properties of TeF 6 and TeF - 6 . A simplified dynamics model based on formation of electronically excited TeF - 6 in the initial electron transfer, followed by inner crossings leading to formation of electronically and vibrationally unexcited TeF - 6 or dissociation to TeF - 5 and other ionic products, has been developed which accounts for the experimental results. The model suggests that the observed two peaks in the differential cross section are due to the production of TeF - 6 (inner peak) or TeF - 5 and other ionic dissociation products (outer peak). The model also suggests that the observed branching ratio requires a vertical electron affinity of < or =1.9 eV, much lower than its adiabatic electron affinity of 3.3 eV

Comprehensive thermodynamic description of the quasiternary system PbTe-GeTe-SnTe

International Nuclear Information System (INIS)

Yashina, Lada V.; Leute, Volkmar; Shtanov, Vladimir I.; Schmidtke, Heinrich M.; Neudachina, Vera S.

2006-01-01

The equilibrium phase diagram of the quasiternary system PbTe-GeTe-SnTe was studied experimentally in the ranges of spinodal demixing and (solid + liquid) equilibrium by means of X-ray diffraction (XRD), electron microprobe analysis (EMA) and differential thermal analysis (DTA). A model description of the phase diagram was done on the base of composition dependent interaction parameters, which were determined for the solid and the liquid phases. The interaction parameters for the quasibinary systems were recalculated in order to reach better correlation between all experimental data. It was shown that the quasiternary phase diagram can be principally described using the interaction parameters for the quasibinary subsystems, but an additional ternary interaction parameter has also to be considered. The local structure of the quasiternary solid solution is described by a four-particle cluster model. Due to the tendency of the solid solution to demix, the probability of the (GeGeGe)Te cluster was found to be higher and that of the (PbGeGe)Te cluster to be lower than it is expected for the purely statistical distribution of the clusters

Electrical performance of phase change memory cells with Ge3Sb2Te6 deposited by molecular beam epitaxy

International Nuclear Information System (INIS)

Boschker, Jos E.; Riechert, Henning; Calarco, Raffaella; Boniardi, Mattia; Redaelli, Andrea

2015-01-01

Here, we report on the electrical characterization of phase change memory cells containing a Ge 3 Sb 2 Te 6 (GST) alloy grown in its crystalline form by Molecular Beam Epitaxy (MBE). It is found that the high temperature growth on the amorphous substrate results in a polycrystalline film exhibiting a rough surface with a grain size of approximately 80–150 nm. A detailed electrical characterization has been performed, including I-V characteristic curves, programming curves, set operation performance, crystallization activation at low temperature, and resistance drift, in order to determine the material related parameters. The results indicate very good alignment of the electrical parameters with the current state-of-the-art GST, deposited by physical vapor deposition. Such alignment enables a possible employment of the MBE deposition technique for chalcogenide materials in the phase change memory technology, thus leading to future studies of as-deposited crystalline chalcogenides as integrated in electrical vehicles

Local structural environments of Ge doped in eutectic Sb-Te film before and after crystallization

Science.gov (United States)

Shin, Sang Yeol; Cheong, Byung-ki; Choi, Yong Gyu

2018-06-01

Electrical phase change device using the Ge-doped eutectic Sb-Te (e.g., Ge1Sb8Te2) film is known to exhibit improved energy efficiency thanks to lowered threshold voltage as well as decreased power consumption for the reset operation, as compared with Ge2Sb2Te5 film. Ge K-edge EXAFS analysis is employed in this study in an effort to elucidate such merits of Ge1Sb8Te2 film in connection with its local atomic arrangements. It is then verified that a Ge atom is four-fold coordinated in its nearest-neighboring shell both in the as-deposited and in the annealed films. It needs to be highlighted that approximately two Sb atoms constitute the Ge tetrahedral units in its amorphous state; however, after being crystallized, heteropolar Ge-Sb bonds hardly exist in this Ge1Sb8Te2 film. It has been known that crystallization temperature and activation energy for crystallization of this Ge1Sb8Te2 composition are greater than those of Ge2Sb2Te5 composition. In addition, these two phase change materials exhibit distinctly different crystallization mechanisms, i.e., nucleation-dominant for Ge2Sb2Te5 film but growth-dominant for Ge1Sb8Te2 film. These discrepancies in the crystallization-related properties are delineated in terms of the local structural changes verified from the present EXAFS analysis.

Initial stages of the ion-beam assisted epitaxial GaN film growth on 6H-SiC(0001)

International Nuclear Information System (INIS)

Neumann, L.; Gerlach, J.W.; Rauschenbach, B.

2012-01-01

Ultra-thin gallium nitride (GaN) films were deposited using the ion-beam assisted molecular-beam epitaxy technique. The influence of the nitrogen ion to gallium atom flux ratio (I/A ratio) during the early stages of GaN nucleation and thin film growth directly, without a buffer layer on super-polished 6H-SiC(0001) substrates was studied. The deposition process was performed at a constant substrate temperature of 700 °C by evaporation of Ga and irradiation with hyperthermal nitrogen ions from a constricted glow-discharge ion source. The hyperthermal nitrogen ion flux was kept constant and the kinetic energy of the ions did not exceed 25 eV. The selection of different I/A ratios in the range from 0.8 to 3.2 was done by varying the Ga deposition rate between 5 × 10 13 and 2 × 10 14 at. cm −2 s −1 . The crystalline surface structure during the GaN growth was monitored in situ by reflection high-energy electron diffraction. The surface topography of the films as well as the morphology of separated GaN islands on the substrate surface was examined after film growth using a scanning tunneling microscope without interruption of ultra-high vacuum. The results show, that the I/A ratio has a major impact on the properties of the resulting ultra-thin GaN films. The growth mode, the surface roughness, the degree of GaN coverage of the substrate and the polytype mixture depend notably on the I/A ratio. - Highlights: ► Ultra-thin epitaxial GaN films prepared by hyperthermal ion-beam assisted deposition. ► Surface structure and topography studied during and after initial growth stages. ► Growth mode dependent on nitrogen ion to gallium atom flux ratio. ► Change from three-dimensional to two-dimensional growth for Ga-rich growth conditions.

Nanoscale interfacial engineering to grow Ge on Si as virtual substrates and subsequent integration of GaAs

Energy Technology Data Exchange (ETDEWEB)

Leonhardt, Darin [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131 (United States); Sheng, Josephine; Cederberg, Jeffrey G.; Li Qiming; Carroll, Malcolm S. [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Han, Sang M., E-mail: meister@unm.ed [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131 (United States)

2010-08-31

We have demonstrated the scalability of a process previously dubbed as Ge 'touchdown' on Si to substantially reduce threading dislocations below 10{sup 7}/cm{sup 2} in a Ge film grown on a 2 inch-diameter chemically oxidized Si substrate. This study also elucidates the overall mechanism of the touchdown process. The 1.4 nm thick chemical oxide is first formed by immersing Si substrates in a solution of H{sub 2}O{sub 2} and H{sub 2}SO{sub 4}. Subsequent exposure to Ge flux creates 3 to 7 nm-diameter voids in the oxide at a density greater than 10{sup 11}/cm{sup 2}. Comparison of data taken from many previous studies and ours shows an exponential dependence between oxide thickness and inverse temperature of void formation. Additionally, exposure to a Ge or Si atom flux decreases the temperature at which voids begin to form in the oxide. These results strongly suggest that Ge actively participates in the reaction with SiO{sub 2} in the void formation process. Once voids are created in the oxide under a Ge flux, Ge islands selectively nucleate within the void openings on the newly exposed Si. Island nucleation and growth then compete with the void growth reaction. At substrate temperatures between 823 and 1053 K, nanometer size Ge islands that nucleate within the voids continue to grow and coalesce into a continuous film over the remaining oxide. Coalescence of the Ge islands is believed to result in the creation of stacking faults in the Ge film at a density of 5 x 10{sup 7}/cm{sup 2}. Additionally, coalescence results in films of 3 {mu}m thickness having a root-mean-square roughness of 8 to 10 nm. We have found that polishing the films with dilute H{sub 2}O{sub 2} results in roughness values below 0.5 nm. However, stacking faults originating at the Ge-SiO{sub 2} interface and terminating at the Ge surface are polished at a slightly reduced rate, and show up as 1 to 2 nm raised lines on the polished Ge surface. These lines are then transferred into the

Effect of temperature and pressure on non-linear conduction in GeTeSe chalcogenide glass

International Nuclear Information System (INIS)

El-Mansy, M.K.

1998-01-01

The I-V characteristic curves were studied in the temperature range 301-359 K and pressure range up to 7.15 x 10 9 Pa which illustrate a non-linear behaviour below (high-resistance region) and beyond (negative-resistance region) a breakdown point characterising Ge 27 Te 62 Se 11 chalcogenide glasses. The general behaviour is shifted towards lower voltage and higher current when the ambient temperature and/or the applied pressure were increased. The non-linear behaviour in the pre breakdown region is discussed according to the Poole-Frenkel field emission of electrons from deep traps located at a depth equal to 0.372eV. The analysis of the effect of field on the non-linear conduction in Ge 27 Te 62 Se 11 chalcogenide glass suggests a modification of the energy difference between filled and empty sites, where the effect of pressure suggests a reduction of the energy gap width. The analysis based on simple thermal effects in the region closer to the breakdown point implies the electrothermal process initiating the negative resistance region. The results of post breakdown region (negative-resistance region) imply the electron hopping between filled and empty localised states at Fermi level. The density of localised states is estimated which lies in the range 5.7 x 10 16 -1.84 x 10 18 cm -3 /eV

Molecular beam epitaxial growth of Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} topological insulators on GaAs (111) substrates: a potential route to fabricate topological insulator p-n junction

Energy Technology Data Exchange (ETDEWEB)

Zeng, Zhaoquan; Morgan, Timothy A.; Li, Chen; Hirono, Yusuke; Hu, Xian; Hawkridge, Michael E.; Benamara, Mourad; Salamo, Gregory J. [Arkansas Institute for Nanoscale Material Sciences and Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Fan, Dongsheng; Yu, Shuiqing [Arkansas Institute for Nanoscale Material Sciences and Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Department of Electrical Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Zhao, Yanfei [International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871 (China); Lee, Joon Sue [The Center for Nanoscale Science and Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States); Wang, Jian [International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871 (China); The Center for Nanoscale Science and Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States); Wang, Zhiming M. [Arkansas Institute for Nanoscale Material Sciences and Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083 (China)

2013-07-15

High quality Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} topological insulators films were epitaxially grown on GaAs (111) substrate using solid source molecular beam epitaxy. Their growth and behavior on both vicinal and non-vicinal GaAs (111) substrates were investigated by reflection high-energy electron diffraction, atomic force microscopy, X-ray diffraction, and high resolution transmission electron microscopy. It is found that non-vicinal GaAs (111) substrate is better than a vicinal substrate to provide high quality Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} films. Hall and magnetoresistance measurements indicate that p type Sb{sub 2}Te{sub 3} and n type Bi{sub 2}Te{sub 3} topological insulator films can be directly grown on a GaAs (111) substrate, which may pave a way to fabricate topological insulator p-n junction on the same substrate, compatible with the fabrication process of present semiconductor optoelectronic devices.

Distortion of Local Atomic Structures in Amorphous Ge-Sb-Te Phase Change Materials

Science.gov (United States)

Hirata, A.; Ichitsubo, T.; Guan, P. F.; Fujita, T.; Chen, M. W.

2018-05-01

The local atomic structures of amorphous Ge-Sb-Te phase-change materials have yet to be clarified and the rapid crystal-amorphous phase change resulting in distinct optical contrast is not well understood. We report the direct observation of local atomic structures in amorphous Ge2Sb2Te5 using "local" reverse Monte Carlo modeling dedicated to an angstrom-beam electron diffraction analysis. The results corroborated the existence of local structures with rocksalt crystal-like topology that were greatly distorted compared to the crystal symmetry. This distortion resulted in the breaking of ideal octahedral atomic environments, thereby forming local disordered structures that basically satisfied the overall amorphous structure factor. The crystal-like distorted octahedral structures could be the main building blocks in the formation of the overall amorphous structure of Ge-Sb-Te.

Thermal, structural and optical properties of new TeO2sbnd Sb2O3sbnd GeO2 ternary glasses

Science.gov (United States)

Pereira, C.; Barbosa, J.; Cassanjes, F. C.; Gonçalves, R. R.; Ribeiro, S. J. L.; Poirier, G.

2016-12-01

In this work the novel glass system TeO2sbnd Sb2O3sbnd GeO2 was investigated and promising glass compositions were selected for further specific studies. Glass samples in the (80-0.8x)TeO2-(20-0.2x)Sb2O3-xGeO2 molar composition were prepared by the melt-quenching method with a glass-forming domain from x = 10 to x = 90. Samples were investigated by XRD, DSC, FTIR, Raman spectroscopy and UV-visible absorption. The XRD and DSC results bring informations about the non-crystalline state and thermal properties of these materials. It has been observed that higher GeO2 contents lead to higher glass transition temperatures and thermal stabilities against crystallization. FTIR and Raman spectroscopies suggest a progressive incorporation of GeO2 in the covalent network of TeO2 with conversion of structural units TeO4 to TeO3. Absorption spectra revealed the high visible transparency of these samples and an increase of the optical band gap with GeO2 addition, in agreement with a decreasing polarizability of the glass network. Er3+ doped and Er3+/Yb3+ codoped samples were also studied with respect to their infrared emission properties and higher GeO2 contents lead to an increase in IR emission intensity at 1,5 μm as well as longer radiative lifetimes. Finally, upconversion emission in the visible were also recorded and were shown to be strongly dependent of the composition.

Two concepts of introducing thin-film superconductivity in Ge and Si by use of Ga-ion implantation

Energy Technology Data Exchange (ETDEWEB)

Skrotzki, Richard [Dresden High Magnetic Field Laboratory (HLD) and Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Department of Chemistry and Food Chemistry, TU Dresden (Germany); Herrmannsdoerfer, Thomas; Fiedler, Jan; Heera, Viton; Voelskow, Matthias; Muecklich, Arndt; Schmidt, Bernd; Skorupa, Wolfgang; Helm, Manfred; Wosnitza, Joachim [Dresden High Magnetic Field Laboratory (HLD) and Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany)

2012-07-01

We report on two unconventional routes of embedding superconducting nanolayers in a semiconducting environment. Ion implantation and subsequent annealing have been used for preparation of superconducting thin-films of Ga-doped germanium (Ge:Ga) as well as 10 nm thin amorphous Ga-rich layers in silicon (Si:Ga). Structural investigations by means of XTEM, EDX, RBS/C, and SIMS have been performed in addition to low-temperature electrical transport and magnetization measurements. Regarding Ge:Ga, we unravel the evolution of T{sub c} with charge-carrier concentration while for Si:Ga recently implemented microstructuring renders critical-current densities or more than 50 kA/cm{sup 2}. Combined with a superconducting onset at around 10 K, this calls for on-chip application in novel heterostructured devices.

Ellipsometry of rough CdTe(211)B-Ge(211) surfaces grown by molecular beam epitaxy

International Nuclear Information System (INIS)

Badano, Giacomo; Ballet, Philippe; Zanatta, Jean-Paul; Baudry, Xavier; Million, Alain; Garland, James W.

2006-01-01

The effect of surface roughness on the ellipsometric response of semiconductor surfaces is investigated. CdTe(211)B layers were grown on Ge(211) by molecular beam epitaxy using less than optimal growth conditions to enhance the formation of surface roughness. Their optical properties, measured by rotating-compensator ellipsometry, showed small but significant sample-to-sample differences not explainable in terms of nanometer-scale roughness. A critical-point analysis established that the critical-point structure of the dielectric function was the same for all samples. This result suggested that the observed sample-to-sample variations were due to macroscopic roughness, which scatters off-specular light into the detector, thereby causing errors. We introduced tentative corrections for off-specular reflection that fitted the observed differences and thus supported the idea that off-specular reflection was responsible for the observed differences. These results were obtained using CdTe but are easily extensible to other rough opaque materials

Contribution to the study of electronic structure of crystalline semiconductors (Si, Ge, GaAs, Gap, ZnTe, ZnSe

Directory of Open Access Journals (Sweden)

Bouhafs B.

2012-06-01

Full Text Available The band structure of semiconductors was described by several theorists since the Fifties. The main objective of the present paper is to do a comparative study between various families of semi-conductors IV (Si,Ge, III-V (GaAs, GaP and II-VI (ZnSe, ZnTe with both methods; tight Binding1 method and pseudo potential method2. This work enables us to understand as well as the mechanism of conduction process in these semiconductors and powers and limits of the above methods. The obtained results allow to conclude that both methods are in a good agreement to describe the morphology of band structures of the cited semiconductors. This encourages us to study in the future the electronic behaviour through the structure of bands for more complex systems such as the heterostructures.

Fabrication and interface electrical properties of Fe3O4/MgO/GaAs(100) spin contacts

NARCIS (Netherlands)

Wong, P.K.J.; Zhang, W.; Zhang, W.; Xu, Y.B.

2010-01-01

Moderately doped n-GaAs(100) substrates (n= 5 x 10 17cm3 ) with In Ohmic back contacts were annealed in the growth chamber with a base pressure of 1 x 10-8 mbar for 60 min at 830 K prior to the film stack growth. MgO layer was then grown by e-beam evaporation at a rate of 2 Amin-1 while the

Attenuation and Emittance Growth of 450 GeV and 7 TeV Proton Beams in Low-Z Absorber Elements

CERN Document Server

Kadi, Y; Goddard, B; Schmidt, R

2004-01-01

The intensity of the LHC beams will be several orders of magnitude above the damage thresholds for equipment. Passive protection of accelerator equipment against failures during beam transfer, injection and dumping of the beam with diluters and collimators is foreseen. These protection devices must be robust in case of beam impact, and low-Z materials such as carbon are favored. In these diluters, the reduction of the energy density is determined both by the attenuation due to inelastic nuclear collisions and by the emittance growth of the surviving protons due to elastic scattering processes. The physics principles leading to attenuation and emittance growth for a hadron beam traversing matter are summarised, and FLUKA simulation results for 450 GeV and 7 TeV proton beams on low-Z absorbers are compared with these predictions. Design criteria for the LHC absorbers are derived from these results.

Europeans build 10-GigE network

CERN Multimedia

2003-01-01

" CERN, SURFnet and the University of Amsterdam announced that they have succeeded in building and testing a Trans European 10 Gbps Ethernet (10 GE) network. Crossing four countries and spanning 1700 km, the network uses the new 10 GE WAN PHY transmission technology capable of transmitting the equivalent of 1.5 complete data CDs every second" (1 page).

Study of Fermion Pair Production in $e^{+}e^{-}$ Collisions at 130-183 GeV

CERN Document Server

Barate, R.; Ghez, Philippe; Goy, C.; Jezequel, S.; Lees, J.P.; Martin, F.; Merle, E.; Minard, M.N.; Pietrzyk, B.; Alemany, R.; Casado, M.P.; Chmeissani, M.; Crespo, J.M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, L.; Grauges, E.; Juste, A.; Martinez, M.; Merino, G.; Miquel, R.; Mir, L.M.; Morawitz, P.; Pacheco, A.; Park, I.C.; Riu, I.; Colaleo, A.; Creanza, D.; De Palma, M.; Gelao, G.; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Becker, U.; Boix, G.; Cattaneo, M.; Ciulli, V.; Dissertori, G.; Drevermann, H.; Forty, R.W.; Frank, M.; Gianotti, F.; Halley, A.W.; Hansen, J.B.; Harvey, John; Janot, P.; Jost, B.; Lehraus, I.; Leroy, O.; Loomis, C.; Maley, P.; Mato, P.; Minten, A.; Moutoussi, A.; Ranjard, F.; Rolandi, Gigi; Rousseau, D.; Schlatter, D.; Schmitt, M.; Schneider, O.; Tejessy, W.; Teubert, F.; Tomalin, I.R.; Tournefier, E.; Vreeswijk, M.; Wright, A.E.; Ajaltouni, Z.; Badaud, F.; Chazelle, G.; Deschamps, O.; Dessagne, S.; Falvard, A.; Ferdi, C.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.C.; Pallin, D.; Perret, P.; Podlyski, F.; Hansen, J.D.; Hansen, J.R.; Hansen, P.H.; Nilsson, B.S.; Rensch, B.; Waananen, A.; Daskalakis, G.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Blondel, A.; Brient, J.C.; Machefert, F.; Rouge, A.; Swynghedauw, M.; Tanaka, R.; Valassi, A.; Videau, H.; Focardi, E.; Parrini, G.; Zachariadou, K.; Cavanaugh, R.; Corden, M.; Georgiopoulos, C.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Cerutti, F.; Chiarella, V.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G.P.; Passalacqua, L.; Pepe-Altarelli, M.; Chalmers, M.; Curtis, L.; Lynch, J.G.; Negus, P.; O'Shea, V.; Raeven, B.; Raine, C.; Smith, D.; Teixeira-Dias, P.; Thompson, A.S.; Ward, J.J.; Buchmuller, O.; Dhamotharan, S.; Geweniger, C.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E.E.; Putzer, A.; Sommer, J.; Tittel, K.; Werner, S.; Wunsch, M.; Beuselinck, R.; Binnie, D.M.; Cameron, W.; Dornan, P.J.; Girone, M.; Goodsir, S.; Marinelli, N.; Martin, E.B.; Nash, J.; Nowell, J.; Sciaba, A.; Sedgbeer, J.K.; Spagnolo, P.; Thomson, Evelyn J.; Williams, M.D.; Ghete, V.M.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Betteridge, A.P.; Bowdery, C.K.; Buck, P.G.; Colrain, P.; Crawford, G.; Ellis, G.; Finch, A.J.; Foster, F.; Hughes, G.; Jones, R.W.L.; Robertson, N.A.; Williams, M.I.; van Gemmeren, P.; Giehl, I.; Holldorfer, F.; Hoffmann, C.; Jakobs, K.; Kleinknecht, K.; Krocker, M.; Nurnberger, H.A.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.G.; Schmeling, S.; Wachsmuth, H.; Zeitnitz, C.; Ziegler, T.; Aubert, J.J.; Benchouk, C.; Bonissent, A.; Carr, J.; Coyle, P.; Ealet, A.; Fouchez, D.; Motsch, F.; Payre, P.; Talby, M.; Thulasidas, M.; Tilquin, A.; Aleppo, M.; Antonelli, M.; Ragusa, F.; Berlich, R.; Buescher, Volker; Dietl, H.; Ganis, G.; Huttmann, K.; Lutjens, G.; Mannert, C.; Manner, W.; Moser, H.G.; Schael, S.; Settles, R.; Seywerd, H.; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Azzurri, P.; Boucrot, J.; Callot, O.; Chen, S.; Davier, M.; Duflot, L.; Grivaz, J.F.; Heusse, P.; Jacholkowska, A.; Kado, M.; Lefrancois, J.; Serin, L.; Veillet, J.J.; Videau, I.; de Viviede Regie, J.B.; Zerwas, D.; Bagliesi, Giuseppe; Bettarini, S.; Boccali, T.; Bozzi, C.; Calderini, G.; Dell'Orso, R.; Ferrante, I.; Giassi, A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P.S.; Messineo, A.; Palla, F.; Rizzo, G.; Sanguinetti, G.; Sguazzoni, G.; Tenchini, R.; Vannini, C.; Venturi, A.; Verdini, P.G.; Blair, G.A.; Coles, J.; Cowan, G.; Green, M.G.; Hutchcroft, D.E.; Jones, L.T.; Medcalf, T.; Strong, J.A.; von Wimmersperg-Toeller, J.H.; Botterill, D.R.; Clifft, R.W.; Edgecock, T.R.; Norton, P.R.; Thompson, J.C.; Bloch-Devaux, Brigitte; Colas, P.; Fabbro, B.; Faif, G.; Lancon, E.; Lemaire, M.C.; Locci, E.; Perez, P.; Przysiezniak, H.; Rander, J.; Renardy, J.F.; Rosowsky, A.; Trabelsi, A.; Tuchming, B.; Vallage, B.; Black, S.N.; Dann, J.H.; Kim, H.Y.; Konstantinidis, N.; Litke, A.M.; McNeil, M.A.; Taylor, G.; Booth, C.N.; Cartwright, S.; Combley, F.; Hodgson, P.N.; Kelly, M.S.; Lehto, M.; Thompson, L.F.; Affholderbach, K.; Boehrer, Armin; Brandt, S.; Grupen, C.; Misiejuk, A.; Prange, G.; Sieler, U.; Giannini, G.; Gobbo, B.; Putz, J.; Rothberg, J.; Wasserbaech, S.; Williams, R.W.; Armstrong, S.R.; Charles, E.; Elmer, P.; Ferguson, D.P.S.; Gao, Y.; Gonzalez, S.; Greening, T.C.; Hayes, O.J.; Hu, H.; Jin, S.; McNamara, P.A., III; Nachtman, J.M.; Nielsen, J.; Orejudos, W.; Pan, Y.B.; Saadi, Y.; Scott, I.J.; Walsh, J.; Wu, Sau Lan; Wu, X.; Zobernig, G.

2000-01-01

The cross sections and forward-backward asymmetries of hadronic and leptonic events produced in e+e- collisions at centre-of-mass energies of 130-183 GeV are presented. Results for ee, mumu, tautau, qq, bb and cc production show no significant deviation from the Standard Model predictions. This enable constraints to be set upon physics beyond the Standard Model such as four-fermion contact interactions, leptoquarks, Z' bosons and R-parity violating squarks and sneutrinos. Limits on the energy scale Lambda of eeff contact interactions are typically in the range from 2-10 TeV. Limits on R-parity violating sneutrinos reach masses of a few hundred GeV for large values of their Yukawa couplings.

Atomic diffusion in laser irradiated Ge rich GeSbTe thin films for phase change memory applications

Science.gov (United States)

Privitera, S. M. S.; Sousa, V.; Bongiorno, C.; Navarro, G.; Sabbione, C.; Carria, E.; Rimini, E.

2018-04-01

The atomic diffusion and compositional variations upon melting have been studied by transmission electron microscopy and electron energy loss spectroscopy in Ge rich GeSbTe films, with a composition optimized for memory applications. Melting and quenching has been achieved by laser pulses, in order to study pure thermal diffusion without electric field induced electromigration. The effect of different laser energy densities has been investigated. The diffusion of Ge atoms in the molten phase is found to be a prominent mechanism and, by employing finite elements computational analysis, a diffusion coefficient of Ge on the order of 5  ×  10-5 cm2 s-1 has been estimated.

Peculiar atomic dynamics in liquid GeTe with asymmetrical bonding: Observation by inelastic x-ray scattering

Science.gov (United States)

Inui, M.; Koura, A.; Kajihara, Y.; Hosokawa, S.; Chiba, A.; Kimura, K.; Shimojo, F.; Tsutsui, S.; Baron, A. Q. R.

2018-05-01

Collective dynamics in liquid GeTe was investigated by inelastic x-ray scattering at 2 ≤Q ≤31 nm-1 . The dynamic structure factor shows clear inelastic excitations. The excitation energies at low Q disperse with increasing Q , consistent with the behavior of a longitudinal-acoustic excitation. The dispersion curve has a flat-topped region around the pseudo-Brillouin-zone boundary, similar to what is observed in liquid Bi [Inui et al., Phys. Rev. B 92, 054206 (2015), 10.1103/PhysRevB.92.054206]. The dynamic structure factor shows a low-frequency excitation, and its coupling with the longitudinal-acoustic mode plays an important role for a flat-topped dispersion. From these results, it is inferred that atomic dynamics in liquid GeTe is strongly affected by a Peierls distortion similar to liquid Bi. By comparing the momentum transfer dependence of the excitation energy and quasielastic linewidth to partial structure factors obtained by our own ab initio molecular dynamics simulation for liquid GeTe, the quasielastic and inelastic components were found to be correlated with Te-Te and Ge-(Ge,Te) partial structure factors, respectively.

ReGaTE: Registration of Galaxy Tools in Elixir

DEFF Research Database (Denmark)

Doppelt-Azeroual, Olivia; Mareuil, Fabien; Deveaud, Eric

2017-01-01

such popular environment is the Galaxy framework, with currently more than 80 publicly available Galaxy servers around the world. In the context of a generic registry for bioinformatics software, such as bio.tools, Galaxy instances constitute a major source of valuable content. Yet there has been, to date...... of their services while enriching the software discovery function that bio.tools provides for its users. The source code of ReGaTE is freely available on Github at https://github.com/C3BI-pasteur-fr/ReGaTE....

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)

Reduction of 68Ge activity containing liquid waste from 68Ga PET chemistry in nuclear medicine and radiopharmacy by solidification.

Science.gov (United States)

de Blois, Erik; Chan, Ho Sze; Roy, Kamalika; Krenning, Eric P; Breeman, Wouter A P

PET with 68 Ga from the TiO 2 - or SnO 2 - based 68 Ge/ 68 Ga generators is of increasing interest for PET imaging in nuclear medicine. In general, radionuclidic purity ( 68 Ge vs. 68 Ga activity) of the eluate of these generators varies between 0.01 and 0.001%. Liquid waste containing low amounts of 68 Ge activity is produced by eluting the 68 Ge/ 68 Ga generators and residues from PET chemistry. Since clearance level of 68 Ge activity in waste may not exceed 10 Bq/g, as stated by European Directive 96/29/EURATOM, our purpose was to reduce 68 Ge activity in solution from >10 kBq/g to <10 Bq/g; which implies the solution can be discarded as regular waste. Most efficient method to reduce the 68 Ge activity is by sorption of TiO 2 or Fe 2 O 3 and subsequent centrifugation. The required 10 Bq per mL level of 68 Ge activity in waste was reached by Fe 2 O 3 logarithmically, whereas with TiO 2 asymptotically. The procedure with Fe 2 O 3 eliminates ≥90% of the 68 Ge activity per treatment. Eventually, to simplify the processing a recirculation system was used to investigate 68 Ge activity sorption on TiO 2 , Fe 2 O 3 or Zeolite. Zeolite was introduced for its high sorption at low pH, therefore 68 Ge activity containing waste could directly be used without further interventions. 68 Ge activity containing liquid waste at different HCl concentrations (0.05-1.0 M HCl), was recirculated at 1 mL/min. With Zeolite in the recirculation system, 68 Ge activity showed highest sorption.

Electrical properties and surface morphology of electron beam evaporated p-type silicon thin films on polyethylene terephthalate for solar cells applications

Energy Technology Data Exchange (ETDEWEB)

Ang, P. C.; Ibrahim, K.; Pakhuruddin, M. Z. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, Minden 11800 Penang (Malaysia)

2015-04-24

One way to realize low-cost thin film silicon (Si) solar cells fabrication is by depositing the films with high-deposition rate and manufacturing-compatible electron beam (e-beam) evaporation onto inexpensive foreign substrates such as glass or plastic. Most of the ongoing research is reported on e-beam evaporation of Si films on glass substrates to make polycrystalline solar cells but works combining both e-beam evaporation and plastic substrates are still scarce in the literature. This paper studies electrical properties and surface morphology of 1 µm electron beam evaporated Al-doped p-type silicon thin films on textured polyethylene terephthalate (PET) substrate for application as an absorber layer in solar cells. In this work, Si thin films with different doping concentrations (including an undoped reference) are prepared by e-beam evaporation. Energy dispersion X-ray (EDX) showed that the Si films are uniformly doped by Al dopant atoms. With increased Al/Si ratio, doping concentration increased while both resistivity and carrier mobility of the films showed opposite relationships. Root mean square (RMS) surface roughness increased. Overall, the Al-doped Si film with Al/Si ratio of 2% (doping concentration = 1.57×10{sup 16} atoms/cm{sup 3}) has been found to provide the optimum properties of a p-type absorber layer for fabrication of thin film Si solar cells on PET substrate.

Ultrafast crystallization and thermal stability of In-Ge doped eutectic Sb70Te30 phase change material

International Nuclear Information System (INIS)

Lee Meiling; Miao Xiangshui; Ting Leehou; Shi Luping

2008-01-01

Effect of In and Ge doping in the form of In 2 Ge 8 Sb 85 Te 5 on optical and thermal properties of eutectic Sb 70 Te 30 alloys was investigated. Crystalline structure of In 2 Ge 8 Sb 85 Te 5 phase change material consists of a mixture of phases. Thermal analysis shows higher crystallization temperature and activation energy for crystallization. Isothermal reflectivity-time measurement shows a growth-dominated crystallization mechanism. Ultrafast crystallization speed of 30 ns is realized upon irradiation by blue laser beam. The use of ultrafast and thermally stable In 2 Ge 8 Sb 85 Te 5 phase change material as mask layer in aperture-type super-resolution near-field phase change disk is realized to increase the carrier-to-noise ratio and thermal stability

A multi-TeV compact $e^{+} e^{-}$ linear collider

CERN Document Server

Wilson, Ian H

2000-01-01

The CLIC study of a high energy (0.5-5 TeV), high luminosity (10/sup 34/-10/sup 35/ cm/sup -2/ sec/sup -1/) e/sup +or-/ linear collider is presented. Beam acceleration using high frequency (30 GHz) normal- conducting structures operating at high accelerating fields (150 MV /m) significantly reduces the length and, in consequence, the cost of the linac. Based on new beam and linac parameters derived from a recently developed set of general scaling laws for linear colliders, the beam stability is shown to be similar to lower frequency designs in spite of the strong wake-field dependency on frequency. The drive beam generation scheme for RF power production by the so-called "Two Beam Acceleration (TBA)" method is described. It uses a thermionic gun and a fully-loaded normal-conducting linac operating at low frequency (937 MHz) to generate and accelerate the drive beam bunches, and RF multiplication by funnelling in compressor rings to produce the desired bunch structure. Recent 30 GHz hardware developments and r...

Diffusion of $^{56}$Co in GaAs and SiGe alloys

CERN Multimedia

Koskelo, O K

2007-01-01

Following our previous diffusion studies performed with the modified radiotracer technique, we propose to determine the diffusion of cobalt in GaAs and SiGe alloys under intrinsic conditions. In the literature only three previous studies for Co diffusion in GaAs may be found and the results differ by over four orders of magnitude from each other. For Co diffusion in SiGe alloys no previous data is available in the literature. For Co diffusion in Ge one study may be found but the results have been obtained with material having increased dislocation density. For dislocation-free material no previous measurements are available. For such experiments we ask for two runs of 3 shifts (total of 6 shifts) with $^{56}$Co$^{+}$ ion beam.

Ultra-low-energy (<10 eV/u) ion beam bombardment effect on naked DNA

Energy Technology Data Exchange (ETDEWEB)

Thopan, P. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongkumkoon, P. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Prakrajang, K. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Suwannakachorn, D. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

2014-05-01

Highlights: • Decelerated ultra-low energy ion beam bombarded naked DNA. • DNA form change induced by ion bombardment was investigated. • N-ion bombardment at 32 eV induced DNA single and double strand breaks. • Ar-ion bombardment at a-few-hundreds eV induced DNA single strand break. - Abstract: Since ion energy deposition in the ion-bombarded materials dominantly occurs in the low-energy range, it is very interesting to know effects from ultra-low-energy ion interaction with DNA for understanding ion-beam-induced genetic mutation. Tens-keV Ar- and N-ion beams were decelerated to ultra-low energy ranging from 20 to 100 eV, or only a few to 10 eV/u, to bombard naked plasmid DNA. The bombarded DNA was analyzed using gel electrophoresis for DNA form changes. The original DNA supercoiled form was found to change to relaxed and linear forms, indicating single or double strand breaks after bombarded by tens-eV ion beam. N-ion beam was found more effective in inducing DNA change and mutation than Ar-ion beam. The study demonstrated that the ion bombardment with energy as low as several-tens eV was able to break DNA strands and thus potentially to cause genetic modification of biological cells. The experimental results were discussed in terms of direct atomic collision between the ions and DNA atoms.

Ultra-low-energy (<10 eV/u) ion beam bombardment effect on naked DNA

International Nuclear Information System (INIS)

Thopan, P.; Thongkumkoon, P.; Prakrajang, K.; Suwannakachorn, D.; Yu, L.D.

2014-01-01

Highlights: • Decelerated ultra-low energy ion beam bombarded naked DNA. • DNA form change induced by ion bombardment was investigated. • N-ion bombardment at 32 eV induced DNA single and double strand breaks. • Ar-ion bombardment at a-few-hundreds eV induced DNA single strand break. - Abstract: Since ion energy deposition in the ion-bombarded materials dominantly occurs in the low-energy range, it is very interesting to know effects from ultra-low-energy ion interaction with DNA for understanding ion-beam-induced genetic mutation. Tens-keV Ar- and N-ion beams were decelerated to ultra-low energy ranging from 20 to 100 eV, or only a few to 10 eV/u, to bombard naked plasmid DNA. The bombarded DNA was analyzed using gel electrophoresis for DNA form changes. The original DNA supercoiled form was found to change to relaxed and linear forms, indicating single or double strand breaks after bombarded by tens-eV ion beam. N-ion beam was found more effective in inducing DNA change and mutation than Ar-ion beam. The study demonstrated that the ion bombardment with energy as low as several-tens eV was able to break DNA strands and thus potentially to cause genetic modification of biological cells. The experimental results were discussed in terms of direct atomic collision between the ions and DNA atoms

Production and decay of the F-meson in e+e- annihilation at 10 GeV centre-of-mass energy

International Nuclear Information System (INIS)

Albrecht, H.; Binder, U.; Drews, G.; Harder, G.; Hasemann, H.; Philipp, A.; Schmidt-Parzefall, W.; Schroeder, H.; Schulz, H.D.; Selonke, F.; Wurth, R.; Drescher, A.; Graewe, B.; Hofmann, W.; Markees, A.; Matthiesen, U.; Scheck, H.; Spengler, J.; Wegener, D.; Edwards, K.W.; Yun, J.C.; Frisken, W.R.; Fukunaga, C.; Goddard, M.; Gilkinson, D.J.; Gingrich, D.M.; Kim, P.C.H.; Kutschke, R.; MacFarlane, D.B.; McKenna, J.A.; Orr, R.S.; Padley, P.; Prentice, J.D.; Seywerd, H.C.J.; Stacey, B.J.; Yoon, T.S.; Ammar, R.; Coppage, D.; Davis, R.; Kanekal, S.; Kwak, N.; Boeckmann, P.; Joensson, L.; Oku, Y.; Childers, R.; Darden, C.W.; Gennow, H.

1984-12-01

Using the ARGUS detector at DORIS, we have observed the production of Fsup(+-) mesons in e + e - annihilation at a centre of mass energy of 10 GeV through their subsequent decays into PHIπsup(+-) and PHIπ + π - πsup(+-). The values obtained for [R(e + e - -> F x). Branching Ratio] are (1.47 +- 0.32 +- 0.20)% and (1.63 +- 0.42 +- 0.41)% respectively. The observed mass is (1973.6 +- 2.6 +- 3.0) MeV/c 2 . The F momentum spectrum is as expected for the fragmentation of c quarks into charmed mesons, but is somewhat softer than for fragmentation into Dsup(*) mesons. The relevant angular distributions are consistent with a spin zero assignment of the F meson. (orig.)

The first fermi-lat catalog of sources above 10 GeV

Energy Technology Data Exchange (ETDEWEB)

Ackermann, M.; Ajello, M.; Allafort, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Belfiore, A.; Bellazzini, R.; Bernieri, E.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Campana, R.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D' Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Desiante, R.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Franckowiak, A.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hewitt, J.; Hill, A. B.; Horan, D.; Hughes, R. E.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Kataoka, J.; Kawano, T.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Massaro, E.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Okumura, A.; Orienti, M.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Romani, R. W.; Roth, M.; Saz Parkinson, P. M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stawarz, Łukasz; Strong, A. W.; Suson, D. J.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Werner, M.; Winer, B. L.; Wood, K. S.; Wood, M.

2013-11-14

We present a catalog of gamma-ray sources at energies above 10 GeV based on data from the Large Area Telescope (LAT) accumulated during the first three years of the Fermi Gamma-ray Space Telescope mission. The first Fermi-LAT catalog of >10GeV sources (1FHL) has 514 sources. For each source we present location, spectrum, a measure of variability, and associations with cataloged sources at other wavelengths. We found that 449 (87%) could be associated with known sources, of which 393 (76% of the 1FHL sources) are active galactic nuclei. Of the 27 sources associated with known pulsars, we find 20 (12) to have significant pulsations in the range >10GeV (>25GeV). In this work we also report that, at energies above 10 GeV, unresolved sources account for 27+/-8 % of the isotropic gamma-ray background, while the unresolved Galactic population contributes only at the few percent level to the Galactic diffuse background. We also highlight the subset of the 1FHL sources that are best candidates for detection at energies above 50-100 GeV with current and future ground-based gamma-ray observatories.

Investigation of beam self-polarization in the future e+e- circular collider

Science.gov (United States)

Gianfelice-Wendt, E.

2016-10-01

The use of resonant depolarization has been suggested for precise beam energy measurements (better than 100 keV) in the e+e- Future Circular Collider (FCC-e+e-) for Z and W W physics at 45 and 80 GeV beam energy respectively. Longitudinal beam polarization would benefit the Z peak physics program; however it is not essential and therefore it will be not investigated here. In this paper the possibility of self-polarized leptons is considered. Preliminary results of simulations in presence of quadrupole misalignments and beam position monitors (BPMs) errors for a simplified FCC-e+e- ring are presented.

Electro-optical 1 x 2, 1 x N and N x N fiber-optic and free-space switching over 1.55 to 3.0 μm using a Ge-Ge(2)Sb(2)Te(5)-Ge prism structure.

Science.gov (United States)

Hendrickson, Joshua; Soref, Richard; Sweet, Julian; Majumdar, Arka

2015-01-12

New device designs are proposed and theoretical simulations are performed on electro-optical routing switches in which light beams enter and exit the device either from free space or from lensed fibers. The active medium is a ~100 nm layer of phase change material (Ge(2)Sb(2)Te(5) or GeTe) that is electrically "triggered" to change its phase, giving "self-holding" behavior in each of two phases. Electrical current is supplied to that film by a pair of transparent highly doped conducting Ge prisms on both sides of the layer. For S-polarized light incident at ~80° on the film, a three-layer Fabry-Perot analysis, including dielectric loss, predicts good 1 x 2 and 2 x 2 switch performance at infrared wavelengths of 1.55, 2.1 and 3.0 μm, although the performance at 1.55 μm is degraded by material loss and prism mismatch. Proposals for in-plane and volumetric 1 x 4 and 4 x 4 switches are also presented. An unpolarized 1 x 2 switch projects good performance at mid infrared.

Direct observation of phase transition of GeSbTe thin films by Atomic Force Microscope

Energy Technology Data Exchange (ETDEWEB)

Yang Fei [National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Xu Ling, E-mail: xuling@nju.edu.cn [National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Zhang Rui; Geng Lei; Tong Liang; Xu Jun [National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Su Weining; Yu Yao [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Ma Zhongyuan; Chen Kunji [National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China)

2012-10-01

Graphical abstract: Nano-sized marks on GST thin film were fabricated using Conductive-AFM (Atomic Force Microscope). The AFM morphology images show that the marks are ablated at the center and a raised ring surrounding it. Highlights: Black-Right-Pointing-Pointer Microstructure of GeSbTe thin films was characterized by XRD and AFM. Black-Right-Pointing-Pointer Annealing and applying electrical field can induce crystallization on thin film. Black-Right-Pointing-Pointer Conductive-AFM was used to modify the surface of GeSbTe thin film. - Abstract: GeSbTe (GST) thin films were deposited on quartz substrates using electron beam evaporation system and then annealed in nitrogen atmosphere at different temperatures, ranging from 20 Degree-Sign C to 300 Degree-Sign C. X-ray diffraction (XRD) and Atomic Force microscope (AFM) measurements were used to characterize the as-deposited and post-annealed thin films. Annealing treatment was found to induce changes on microstructure, surface roughness and grain size, indicating that with the increase of annealing temperature, the amorphous GST films first changed to face-centered-cubic (fcc) phase and then the stable hexagonal (hex) phase. Meanwhile, conductive-AFM (C-AFM) was used to produce crystallized GST dots on thin films. I-V spectroscopy results show that GST films can switch from amorphous state to crystalline state at threshold voltage. After switching, I-V curve exhibits ohmic characteristic, which is usually observed in crystallized GST films. By applying repeated I-V spectroscopies on the thin films, crystallized nuclei were observed. As the times of I-V spectroscopies increases, the area of written dots increases, and the center of the mark begin to ablate. The AFM images show that the shape of marks is an ablated center with a raised ring surrounding it.

K/sub 4/Si/sub 4/Te/sub 10/, the first tellurosilicate with adamantane-like Si/sub 4/Te/sub 10//sup 4 -/ anions

Energy Technology Data Exchange (ETDEWEB)

Eisenmann, B; Schaefer, H [Technische Hochschule Darmstadt (Germany, F.R.). Fachbereich Anorganische Chemie und Kernchemie

1982-08-01

The new compound K/sub 4/Si/sub 4/Te/sub 10/ crystallizes in the orthorhombic system (space group Pnma) with following constants: a = 2125.8(8) pm, b = 1200.5(7) pm, c = 1060.8(7) pm. The structure is characterized by SiTe/sub 4/ tetrahedra, connected by common corners to adamantane-like Si/sub 4/Te/sub 10//sup 4 -/ units.

Ultra-broadband Nonlinear Microwave Monolithic Integrated Circuits in SiGe, GaAs and InP

DEFF Research Database (Denmark)

Krozer, Viktor; Johansen, Tom Keinicke; Djurhuus, Torsten

2006-01-01

.5 GHz and ≫ 10 GHz for SiGe BiCMOS and GaAs MMIC, respectively. Analysis of the frequency behaviour of frequency converting devices is presented for improved mixer design. Millimeter-wave front-end components for advanced microwave imaging and communications purposes have also been demonstrated......Analog MMIC circuits with ultra-wideband operation are discussed in view of their frequency limitation and different circuit topologies. Results for designed and fabricated frequency converters in SiGe, GaAs, and InP technologies are presented in the paper. RF type circuit topologies exhibit a flat...... conversion gain with a 3 dB bandwidth of 10 GHz for SiGe and in excess of 20 GHz for GaAs processes. The concurrent LO-IF isolation is better than -25 dB, without including the improvement due to the combiner circuit. The converter circuits exhibit similar instantaneous bandwidth at IF and RF ports of ≫ 7...

Fundamental optical absorption edge in MnGa2Te4 single crystals

International Nuclear Information System (INIS)

Medvedkin, G.A.; Rud, Yu.V.; Tairov, M.A.

1988-01-01

A study is made of the optical properties of oriented MnGa 2 Te 4 crystals in the region of the fundamental absorption edge. The energy gap width for the temperatures 77, 300, and 370 K is determined to be E G = 1.635, 1.52, and 1.50 eV. The spectral response α(ℎω/2π) is found to follow Urbach's rule thoughout the temperature range studied, the slope of the absorption edge remaining constant (α = 10 2 cm -1 ). Crystal annealing with subsequent rapid cooling results in a shift of the absorption edge longward by 25 meV with the exponential form of α(ℎω/2π) prevailing over the range T = 77 to 370 K. An analysis shows the optical absorption in the region of the fundamental edge to be a sum of the effects coming from the density-of-states tails, local scattering centers associated with a high vacancy concentration, and electron-phonon interaction. Optical linear dichroism of the absorption edge of MnGa 2 Te 4 single crystals with pseudotetragonal structure is revealed and studied. The single crystals are established to be optically uniaxial, their optical transmission dichroism being negative. It is shown that the minimal direct optical transitions in MnGa 2 Te 4 are allowed in the E parallel c polarization in the temperature range 77 to 370 K, the crystal-field splitting of the valence band increasing with temperature. (author)

Fast and Precise Beam Energy Measurement using Compton Backscattering at e+e- Colliders

CERN Document Server

Kaminskiy, V V; Muchnoi, N Yu; Zhilich, V N

2017-01-01

The report describes a method for a fast and precise beam energy measurement in the beam energy range 0.5-2 GeV and its application at various e+e- colliders. Low-energy laser photons interact head-on with the electron or positron beam and produce Compton backscattered photons whose energy is precisely measured by HPGe detector. The method allows measuring the beam energy with relative accuracy of ∼2-5.10-5. The method was successfully applied at VEPP-4M, VEPP-3, VEPP-2000 (BINP, Russia) and BEPC-II (IHEP, China).

Propriedades estruturais e térmicas de vidros teluretos 20Li2O-80TeO2 Structural and thermal properties of tellurite 20Li2O-80TeO2 glasses

Directory of Open Access Journals (Sweden)

E. Idalgo

2007-09-01

Full Text Available O presente trabalho reporta estudos sobre a cristalização em vidros teluretos 20Li2O-80TeO2 induzida a partir de tratamentos térmicos realizados sobre vidros com tamanho de partículas entre 38 µm e 75 µm. Estes estudos foram conduzidos em duas matrizes vítreas tratadas e não tratadas termicamente para aliviar as tensões após o quenching, utilizando-se de forma combinada às técnicas de difração de raios X, calorimetria diferencial de varredura e espectroscopia no infravermelho. Os resultados revelaram a presença de três fases cristalinas distintas durante o processo de cristalização e apontaram para uma hierarquia tal que as fases alfa-TeO2 e gama-TeO2 cristalizam-se antecipadamente à fase Li2Te2O5 no vidro 20Li2O-80TeO2 sujeito a tensões mecânicas induzidas durante a síntese. No vidro 20Li2O-80TeO2, livre de tensões mecânicas, não foi possível discriminar esta hierarquia de cristalização.This work report crystallization studies on tellurite 20Li2O-80TeO2 glasses induced from heat thermal annealing on glasses with particle size between 38 µm and 75 µm. These studies were conducted on two glass matrix heat thermal annealed and non-annealed to remove the stress after the quenching, by using the X-Ray diffraction analysis, Fourier transform infrared spectroscopy and differential scanning calorimetry techniques. The results shown the presence of three distinct crystalline alpha-TeO2, gamma-TeO2 and Li2Te2O5 phases during the crystallization process, suggesting a crystallization hierarchy on the glass matrix under stress, since the gamma-TeO2 and alpha-TeO2 phases crystallization occurs before the Li2Te2O5 phase. On the glass stress free, this crystallization hierarchy was not clearly determined.

Pressure-assisted reaction bonding between W and Si80Ge20 alloy with Ni as the interlayer

International Nuclear Information System (INIS)

Xu, Y.; Laabs, F.C.; Beaudry, B.J.; Gschneidner, K.A. Jr.

1991-01-01

The conditions and reaction mechanism of W/Ni/Si 80 Ge 20 hot-press bonding have been studied. It was found that a Ni/Si 80 Ge 20 bond can be formed using low pressure, 19.6 MPa, in the temperature range between 780 and 900 degree C in a short time. The kinetics follows a parabolic pattern, suggesting it is a diffusion-controlled process. The activation energy is 2.7 eV and the parabolic rate constant is given by K P = 4.0 x 10 14 exp(-3.2x10 4 /T) (μm 2 /min). The bonding interface has a multilayered structure. A phenomenological mechanism of the bonding formation has been proposed based on scanning electron microscopy observations and energy dispersive spectroscopy. The cracking problem due to thermal stress is discussed based on Oxx's equation. It was found that bonds free from cracks in the Si 80 Ge 20 alloy are formed when the Ni consumption (as measured by the thickness of the nickel layer) is sufficiently small ( 4 . As an interlayer, nickel can join the tungsten sheet and the Si 80 Ge 20 together. It has been also demonstrated that a thin nickel layer formed by vapor deposition on a tungsten sheet may be used as the interlayer in place of nickel sheet

First direct detection limits on sub-GeV dark matter from XENON10.

Science.gov (United States)

Essig, Rouven; Manalaysay, Aaron; Mardon, Jeremy; Sorensen, Peter; Volansky, Tomer

2012-07-13

The first direct detection limits on dark matter in the MeV to GeV mass range are presented, using XENON10 data. Such light dark matter can scatter with electrons, causing ionization of atoms in a detector target material and leading to single- or few-electron events. We use 15  kg day of data acquired in 2006 to set limits on the dark-matter-electron scattering cross section. The strongest bound is obtained at 100 MeV where σ(e)dark-matter masses between 20 MeV and 1 GeV are bounded by σ(e)dark-matter candidates with masses well below the GeV scale.

Complex open-framework germanate built by 8-coordinated Ge 10 clusters

KAUST Repository

Yue, Huijuan; Peskov, Maxim; Sun, Junliang; Zou, Xiaodong

2012-01-01

cluster building units can be concluded. The framework of SU-67 is based on an elaborate topological pattern of connected Ge 10 clusters forming intersecting 10- and 11-ring channels and has a low framework density (12.4 Ge atoms per 1000 ̊ 3). We have

Monolithically integrated InGaAs/GaAs/AlGaAs quantum well laser grown by MOCVD on exact Ge/Si(001) substrate

Energy Technology Data Exchange (ETDEWEB)

Aleshkin, V. Ya.; Dubinov, A. A.; Krasilnik, Z. F.; Kudryavtsev, K. E.; Novikov, A. V.; Yurasov, D. V., E-mail: Inquisitor@ipm.sci-nnov.ru [Institute for Physics of Microstructures of the Russian Academy of Sciences, 603950 Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation); Baidus, N. V.; Samartsev, I. V. [Physical-Technical Research Institute of Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation); Fefelov, A. G. [FGUE “Salut,” 603950 Nizhny Novgorod (Russian Federation); Nekorkin, S. M. [Institute for Physics of Microstructures of the Russian Academy of Sciences, 603950 Nizhny Novgorod (Russian Federation); Physical-Technical Research Institute of Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation); Pavlov, D. A.; Sushkov, A. A. [Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation); Skorokhodov, E. V.; Shaleev, M. V.; Yablonskiy, A. N.; Yunin, P. A. [Institute for Physics of Microstructures of the Russian Academy of Sciences, 603950 Nizhny Novgorod (Russian Federation)

2016-08-08

We report on realization of the InGaAs/GaAs/AlGaAs quantum well laser grown by metallorganic chemical vapor deposition on a virtual Ge-on-Si(001) substrate. The Ge buffer layer has been grown on a nominal Si(001) substrate by solid-source molecular beam epitaxy. Such Ge buffer possessed rather good crystalline quality and smooth surface and so provided the subsequent growth of the high-quality A{sub 3}B{sub 5} laser structure. The laser operation has been demonstrated under electrical pumping at 77 K in the continuous wave mode and at room temperature in the pulsed mode. The emission wavelengths of 941 nm and 992 nm have been obtained at 77 K and 300 K, respectively. The corresponding threshold current densities were estimated as 463 A/cm{sup 2} at 77 K and 5.5 kA/cm{sup 2} at 300 K.

Comparison of structural properties of thermally evaporated CdTe thin films on different substrates

International Nuclear Information System (INIS)

Tariq, G.H.; Anis-ur-Rehman, M.

2011-01-01

The direct energy band gap in the range of 1.5 eV and the high absorption coefficient (105 cm/sup -1/) makes Cadmium Telluride (CdTe) a suitable material for fabrication of thin film solar cells. Thin film solar cells based on CdTe (1 cm area) achieved efficiency of 15.6% on a laboratory scale. CdTe thin films were deposited by thermal evaporation technique under vacuum 2 X 10/sup -5/mbar on glass and stainless steel (SS) substrates. During deposition substrates temperature was kept same at 200 deg. C for all samples. The structural properties were determined by the X-ray Diffraction (XRD) patterns. All samples exhibit polycrystalline nature. Dependence of different structural parameters such as lattice parameter, micro strain, and grain size and dislocation density on thickness was studied. Also the influence of the different substrates on these parameters was investigated. The analysis showed that the preferential orientation of films was dependent on the substrate type. (author)

Complex open-framework germanate built by 8-coordinated Ge 10 clusters

KAUST Repository

Yue, Huijuan

2012-11-19

A novel open-framework germanate |(C 5H 14N 2) 2(C 5H 12N 2) 0.5(H 2O) 2.5|[Ge 12.5O 26(OH) 2] with three-dimensional 10- and 11-ring channels, denoted as SU-67, has been synthesized under hydrothermal conditions using 2-methylpiperazine (MPP) as the structure-directing agent (SDA). The synthesis is intimately related to that of JLG-5, a tubular germanate built from Ge 7 clusters. The influences of synthesis parameters are discussed. A strong influence of the hydrofluoric acid quantity on the resulting cluster building units can be concluded. The framework of SU-67 is based on an elaborate topological pattern of connected Ge 10 clusters forming intersecting 10- and 11-ring channels and has a low framework density (12.4 Ge atoms per 1000 ̊ 3). We have discovered that the topology of SU-67 is a new 8-connected nce-8-I4 1/acd net. Strong hydrogen bonding among the organic SDAs, water molecules, and Ge 10 clusters resulted in helical networks in SU-67. © 2012 American Chemical Society.

Point defect induced degradation of electrical properties of Ga2O3 by 10 MeV proton damage

Science.gov (United States)

Polyakov, A. Y.; Smirnov, N. B.; Shchemerov, I. V.; Yakimov, E. B.; Yang, Jiancheng; Ren, F.; Yang, Gwangseok; Kim, Jihyun; Kuramata, A.; Pearton, S. J.

2018-01-01

Deep electron and hole traps in 10 MeV proton irradiated high-quality β-Ga2O3 films grown by Hydride Vapor Phase Epitaxy (HVPE) on bulk β-Ga2O3 substrates were measured by deep level transient spectroscopy with electrical and optical injection, capacitance-voltage profiling in the dark and under monochromatic irradiation, and also electron beam induced current. Proton irradiation caused the diffusion length of charge carriers to decrease from 350-380 μm in unirradiated samples to 190 μm for a fluence of 1014 cm-2, and this was correlated with an increase in density of hole traps with optical ionization threshold energy near 2.3 eV. These defects most likely determine the recombination lifetime in HVPE β-Ga2O3 epilayers. Electron traps at Ec-0.75 eV and Ec-1.2 eV present in as-grown samples increase in the concentration after irradiation and suggest that these centers involve native point defects.

Investigation of beam self-polarization in the future e^{+}e^{-} circular collider

Directory of Open Access Journals (Sweden)

E. Gianfelice-Wendt

2016-10-01

Full Text Available The use of resonant depolarization has been suggested for precise beam energy measurements (better than 100 keV in the e^{+}e^{-} Future Circular Collider (FCC-e^{+}e^{-} for Z and WW physics at 45 and 80 GeV beam energy respectively. Longitudinal beam polarization would benefit the Z peak physics program; however it is not essential and therefore it will be not investigated here. In this paper the possibility of self-polarized leptons is considered. Preliminary results of simulations in presence of quadrupole misalignments and beam position monitors (BPMs errors for a simplified FCC-e^{+}e^{-} ring are presented.

Partial Pressures of Te2 and Thermodynamic Properties of Ga-Te System

Science.gov (United States)

Su, Ching-Hua; Curreri, Peter A. (Technical Monitor)

2001-01-01

The partial pressures of Te2 in equilibrium with Ga(1-x)Te(x) samples were measured by optical absorption technique from 450 to 1100 C for compositions, x, between 0.333 and 0.612. To establish the relationship between the partial pressure of Te, and the measured optical absorbance, the calibration runs of a pure Te sample were also conducted to determine the Beer's Law constants. The partial pressures of Te2 in equilibrium with the GaTe(s) and Ga2Te3(s)compounds, or the so-called three-phase curves, were established. These partial pressure data imply the existence of the Ga3Te4(s) compound. From the partial pressures of Te2 over the Ga-Te melts, partial molar enthalpy and entropy of mixing for Te were derived and they agree reasonable well with the published data. The activities of Te in the Ga-Te melts were also derived from the measured partial pressures of Te2. These data agree well with most of the previous results. The possible reason for the high activity of Te measured for x less than 0.60 is discussed.

Investigations on the Local Structures and the Spin Hamiltonian Parameters for Cu2+ in (90-x)TeO2-10GeO2-xWO3 Glasses

Science.gov (United States)

Feng, Chun-Rong; Jian, Jun; Chen, Xiao-Hong; Du, Quan; Wang, Ling

2017-12-01

The local structures and the spin Hamiltonian parameters (SHPs) for Cu2+ in (90-x)TeO2-10GeO2-xWO3 glasses are theoretically investigated at various WO3 concentrations (x=7.5, 15, 22.5 and 30 mol%). Subject to the Jahn-Teller effect, the [CuO6]10- groups are found to experience the small or moderate tetragonal elongation distortions (characterised by the relative tetragonal elongation ratios ρ≈0.35-3.09%) in C4 axis. With only three adjusted coefficients a, b and ω, the relevant model parameters (Dq, k and ρ) are described by the Fourier type and linear functions, respectively, and the measured concentration dependences of the d-d transition bands and SHPs are reproduced. The maximum of g∥ and the minimum of |A∥| at x=15 mol% are illustrated from the abrupt decrease of the copper-oxygen electron cloud admixtures or covalency and the obvious decline of the copper 3d-3s (4s) orbital admixtures due to the decreasing electron cloud density around oxygen ligands spontaneously bonding with Cu2+ and Te4+ (W6+), respectively.

Role of heat treatment on structural and optical properties of thermally evaporated Ga{sub 10}Se{sub 81}Pb{sub 9} chalcogenide thin films

Energy Technology Data Exchange (ETDEWEB)

El-Sebaii, A.A., E-mail: ahmedelsebaii@yahoo.com [Department of Physics, Faculty of Science, King Abdulaziz University, 80203 Jeddah 21589 (Saudi Arabia); Khan, Shamshad A. [Department of Physics, St. Andrews College, Gorakhpur 273001 (India); Al-Marzouki, F.M.; Faidah, A.S.; Al-Ghamdi, A.A. [Department of Physics, Faculty of Science, King Abdulaziz University, 80203 Jeddah 21589 (Saudi Arabia)

2012-08-15

Amorphous chalcogenides, based on Se, have become materials of commercial importance and were widely used for optical storage media. The present work deals with the structural and optical properties of Ga{sub 10}Se{sub 81}Pb{sub 9} ternary chalcogenide glass prepared by melt quenching technique. The glass transition, crystallization and melting temperatures of the synthesized glass were measured by non-isothermal DSC measurements at a constant heating rate of 30 K/min. Thin films of thickness 4000 A were prepared by thermal evaporation techniques on glass/Si (1 0 0) wafer substrate. These thin films were thermally annealed for two hours at three different annealing temperatures of 345, 360 and 375 K, which were in between the glass transition and crystallization temperatures of the Ga{sub 10}Se{sub 81}Pb{sub 9} glass. The structural, morphological and optical properties of as-prepared and annealed thin films were studied. Analysis of the optical absorption data showed that the rules of the non-direct transitions predominate. It was also found that the optical band gap decreases while the absorption coefficient, refractive index and extinction coefficient increase with increasing the annealing temperature. Due to the higher values of absorption coefficient and annealing dependence of the optical band gap and optical constants, the investigated material could be used for optical storage. - Highlights: Black-Right-Pointing-Pointer Annealing effect on structure and optical band gap has been investigated. Black-Right-Pointing-Pointer The amorphous nature has been verified by x-ray diffraction and DSC measurements. Black-Right-Pointing-Pointer Thermal annealing causes a decrease in optical band gap in Ga{sub 10}Se{sub 81}Pb{sub 9} thin films. Black-Right-Pointing-Pointer The decrease in optical band gap can be interpreted on the basis of amorphous-crystalline phase transformation. Black-Right-Pointing-Pointer Optical absorption data showed that the rules of the non

Low resistance and transparent Ag/AZO ohmic contact to p-GaN

International Nuclear Information System (INIS)

Han, T.; Wang, T.; Gan, X. W.; Wu, H.; Shi, Y.; Liu, C.

2014-01-01

Silver (Ag)/ aluminum-doped zinc oxide (AZO) films were deposited on p-GaN by using electron beam evaporation. After the annealing process, current -voltage (I-V) measurements were carried out to determine the characteristic of the contacts. The Ag/AZO films annealed at 600 .deg. C were found to present an ohmic contact behavior. The specific contact resistance was calculated to be 9.76 x 10 -4 Ωcm 2 and the transmittance was over 80% for visibly light. The atomic force microscope was used to measure the aggregation of Ag grains which may have been the main factor in the formation of the Ag/AZO ohmic contact to p-GaN.

{sup 197}Au irradiation study of phase-change memory cell with GeSbTe alloy

Energy Technology Data Exchange (ETDEWEB)

Wu, Liangcai; Song, Zhitang; Lian, Jie; Rao, Feng; Liu, Bo; Song, Sannian; Liu, Weili; Feng, Songlin [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Zhou, Xilin; Liu, Xuyan [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100080 (China)

2010-10-15

A {sup 197}Au ion source was used to irradiate a Ge{sub 2}Sb{sub 2}Te{sub 5}-alloy-based phase-change memory (PCM) cell to study the ion-irradiation effect on the properties of the cell. The PCM devices with the tungsten (W) heating electrode of 260 nm diameter were fabricated by 0.18 {mu}m complementary metal-oxide-semiconductor (CMOS) technology. Four different doses (10{sup 10}, 10{sup 11}, 10{sup 12}, and 5 x 10{sup 12} ions/cm{sup 2}, respectively) were applied to irradiate the PCM cell. The samples before and after irradiation were characterized by current-voltage and resistance measurements at room temperature. It is found that the cell properties (resistance value of the amorphous and crystalline states, threshold voltage, and current for phase transition, etc.) have hardly changed, even for the sample irradiated up to 10{sup 12} ions/cm{sup 2} dose, and the cell still has good set-reset operation ability (above 10{sup 5} cycles). Furthermore, the resistance ratio remains at 1000 even after 10{sup 5} cycles of the set-reset operation. The results show the PCM cell with Ge{sub 2}Sb{sub 2}Te{sub 5} alloy has a strong ion-irradiation tolerance. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Structural Analyses of Phase Stability in Amorphous and Partially Crystallized Ge-Rich GeTe Films Prepared by Atomic Layer Deposition.

Science.gov (United States)

Gwon, Taehong; Mohamed, Ahmed Yousef; Yoo, Chanyoung; Park, Eui-Sang; Kim, Sanggyun; Yoo, Sijung; Lee, Han-Koo; Cho, Deok-Yong; Hwang, Cheol Seong

2017-11-29

The local bonding structures of Ge x Te 1-x (x = 0.5, 0.6, and 0.7) films prepared through atomic layer deposition (ALD) with Ge(N(Si(CH 3 ) 3 ) 2 ) 2 and ((CH 3 ) 3 Si) 2 Te precursors were investigated using Ge K-edge X-ray absorption spectroscopy (XAS). The results of the X-ray absorption fine structure analyses show that for all of the compositions, the as-grown films were amorphous with a tetrahedral Ge coordination of a mixture of Ge-Te and Ge-Ge bonds but without any signature of Ge-GeTe decomposition. The compositional evolution in the valence band electronic structures probed through X-ray photoelectron spectroscopy suggests a substantial chemical influence of additional Ge on the nonstoichiometric GeTe. This implies that the ALD process can stabilize Ge-abundant bonding networks like -Te-Ge-Ge-Te- in amorphous GeTe. Meanwhile, the XAS results on the Ge-rich films that had undergone post-deposition annealing at 350 °C show that the parts of the crystalline Ge-rich GeTe became separated into Ge crystallites and rhombohedral GeTe in accordance with the bulk phase diagram, whereas the disordered GeTe domains still remained, consistent with the observations of transmission electron microscopy and Raman spectroscopy. Therefore, amorphousness in GeTe may be essential for the nonsegregated Ge-rich phases and the low growth temperature of the ALD enables the achievement of the structurally metastable phases.

Conduction mechanism and the dielectric relaxation process of a-Se75Te25-xGax (x=0, 5, 10 and 15 at wt%) chalcogenide glasses

International Nuclear Information System (INIS)

Yahia, I.S.; Hegab, N.A.; Shakra, A.M.; Al-Ribaty, A.M.

2012-01-01

Se 75 Te 25-x Ga x (x=0, 5, 10 and 15 at wt%) chalcogenide compositions were prepared by the well known melt quenching technique. Thin films with different thicknesses in the range (185-630 nm) of the obtained compositions were deposited by thermal evaporation technique. X-ray diffraction patterns indicate that the amorphous nature of the obtained films. The ac conductivity and the dielectric properties of the studied films have been investigated in the frequency range (10 2 -10 5 Hz) and in the temperature range (293-333 K). The ac conductivity was found to obey the power low ω s where s≤1 independent of film thickness. The temperature dependence of both ac conductivity and the exponent s can be well interpreted by the correlated barrier hopping (CBH) model. The experimental results of the dielectric constant ε 1 and dielectric loss ε 2 are frequency and temperature dependent. The maximum barrier height W m calculated from the results of the dielectric loss according to the Guintini equation, and agrees with that proposed by the theory of hopping of charge carriers over a potential barrier as suggested by Elliott for chalcogenide glasses. The density of localized state was estimated for the studied film compositions. The variation of the studied properties with Ga content was also investigated. The correlation between the ac conduction and the dielectric properties were verified.

Leptoquark production with polarized γe beams

International Nuclear Information System (INIS)

Aliev, T.M.; Mustafaev, Kh.A.

1991-01-01

Possibilities of single production of the scalar leptoquark and also of its supersymmetric partner in polarized γe beams are studied in E 6 superstring theories. Expressions for the differential and total cross sections are obtained and analyzed. It is shown that the scalar leptoquark of mass 300 GeV can be detected even for a very small interaction constant γ 2 /4π∼10 -2 a and its supersymmetric partner can be detected for γ 2 /4π∼10 -2 a. The spin asymmetry due to the photon-beam polarization and the effect of this polarization on both the differential and the total cross sections are studied in detail. It is shown that study of the spin asymmetry and the effect of the photon-beam polarization can be used to extract information about the leptoquark masses

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.

Optical and structural characterization of GaSb and Te-doped GaSb single crystals

International Nuclear Information System (INIS)

Tirado-Mejia, L.; Villada, J.A.; Rios, M. de los; Penafiel, J.A.; Fonthal, G.; Espinosa-Arbelaez, D.G.; Ariza-Calderon, H.; Rodriguez-Garcia, M.E.

2008-01-01

Optical and structural properties of GaSb and Te-doped GaSb single crystals are reported herein. Utilizing the photoreflectance technique, the band gap energy for doped samples was obtained at 0.814 eV. Photoluminescence (PL) spectra showed a peak at 0.748 eV that according to this research, belongs to electronic states of pure GaSb and not to the longitudinal optical (LO) phonon replica as has been reported by other authors. Analysis of the full width at half maximum (FWHM) values of X-ray diffraction, as well as micro-Raman peaks showed that the inclusion of Te decreases the crystalline quality

Electrical performance of phase change memory cells with Ge{sub 3}Sb{sub 2}Te{sub 6} deposited by molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Boschker, Jos E.; Riechert, Henning; Calarco, Raffaella [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany); Boniardi, Mattia; Redaelli, Andrea [Micron Semiconductor Italia S.r.l., Via C. Olivetti, 2, 20864, Agrate Brianza, MB (Italy)

2015-01-12

Here, we report on the electrical characterization of phase change memory cells containing a Ge{sub 3}Sb{sub 2}Te{sub 6} (GST) alloy grown in its crystalline form by Molecular Beam Epitaxy (MBE). It is found that the high temperature growth on the amorphous substrate results in a polycrystalline film exhibiting a rough surface with a grain size of approximately 80–150 nm. A detailed electrical characterization has been performed, including I-V characteristic curves, programming curves, set operation performance, crystallization activation at low temperature, and resistance drift, in order to determine the material related parameters. The results indicate very good alignment of the electrical parameters with the current state-of-the-art GST, deposited by physical vapor deposition. Such alignment enables a possible employment of the MBE deposition technique for chalcogenide materials in the phase change memory technology, thus leading to future studies of as-deposited crystalline chalcogenides as integrated in electrical vehicles.

Integral measurement of the $^{12}$C(n,p)$^{12}$B reaction up to 10 GeV

CERN Document Server

Žugec, P; Bosnar, D; Ventura, A; Mengoni, A; Altstadt, S; Andrzejewski, J; Audouin, L; Barbagallo, M; Bécares, V; Bečvář, F; Belloni, F; Berthoumieux, E; Billowes, J; Boccone, V; Brugger, M; Calviani, M; Calviño, F; Cano-Ott, D; Carrapiço, C; Cerutti, F; Chiaveri, E; Chin, M; Cortés, G; Cortés-Giraldo, M.A; Cosentino, L; Diakaki, M; Domingo-Pardo, C; Dressler, R; Duran, I; Eleftheriadis, C; Ferrari, A; Finocchiaro, P; Fraval, K; Ganesan, S; García, A R; Giubrone, G; Gómez-Hornillos, M B; Gonçalves, I F; González-Romero, E; Griesmayer, E; Guerrero, C; Gunsing, F; Gurusamy, P; Heinitz, S; Jenkins, D G; Jericha, E; Käppeler, F; Karadimos, D; Kivel, N; Kokkoris, M; Krtička, M; Kroll, J; Langer, C; Lederer, C; Leeb, H; Leong, L S; Meo, S Lo; Losito, R; Manousos, A; Marganiec, J; Martínez, T; Massimi, C; Mastinu, P; Mastromarco, M; Mendoza, E; Milazzo, P M; Mingrone, F; Mirea, M; Mondalaers, W; Musumarra, A; Paradela, C; Pavlik, A; Perkowski, J; Plompen, A; Praena, J; Quesada, J; Rauscher, T; Reifarth, R; Riego, A; Roman, F; Rubbia, C; Sarmento, R; Saxena, A; Schillebeeckx, P; Schmidt, S; Schumann, D; Tagliente, G; Tain, J L; Tarrío, D; Tassan-Got, L; Tsinganis, A; Valenta, S; Vannini, G; Variale, V; Vaz, P; Versaci, R; Vermeulen, M J; Vlachoudis, V; Vlastou, R; Wallner, A; Ware, T; Weigand, M; Weiß, C; Wright, T

2016-01-01

The integral measurement of the $^{12}$C(n,p)$^{12}$B reaction was performed at the neutron time of flight facility n_TOF at CERN. The total number of $^{12}$B nuclei produced per neutron pulse of the n_TOF beam was determined using the activation technique in combination with a time of flight technique. The cross section is integrated over the n_TOF neutron energy spectrum from reaction threshold at 13.6 MeV to 10 GeV. Having been measured up to 1 GeV on basis of the $^{235}$U(n,f) reaction, the neutron energy spectrum above 200 MeV has been reevaluated due to the recent extension of the cross section reference for this particular reaction, which is otherwise considered a standard up to 200 MeV. The results from the dedicated GEANT4 simulations have been used to evaluate the neutron flux from 1 GeV up to 10 GeV. The experimental results related to the $^{12}$C(n,p)$^{12}$B reaction are compared with the evaluated cross sections from major libraries and with the predictions of different GEANT4 models, which m...

Explorations of new phases in the Ga(III)/In(III)-Mo(VI)-Se(IV)/Te(IV)-O systems.

Science.gov (United States)

Kong, Fang; Hu, Chun-Li; Hu, Ting; Zhou, Yong; Mao, Jiang-Gao

2009-07-07

Systematic explorations of new phases in the Ga(III)/In(III)-Mo(VI)-Se(IV)/Te(IV)-O systems by hydrothermal syntheses or solid-state reactions at high-temperature led to four new quaternary compounds, namely, Ga(2)MoQ(2)O(10) (Q = Se, Te), In(2)Mo(2)Se(2)O(13)(H(2)O) and In(2)MoTe(2)O(10). Ga(2)MoQ(2)O(10) (Q = Se, Te) are isostructural and their structures feature a 3D network of gallium selenite/tellurite with 12-member ring tunnels along b-axis, the distorted MoO(6) octahedra are attached on the wall of the above tunnels. The structure of In(2)Mo(2)Se(2)O(13)(H(2)O) features a new pillared-layered architecture composed of 2D indium(III) selenite layers that are interconnected by Mo(2)O(10) dimers, forming 8-membered ring tunnels along the b-axis. The structure of In(2)MoTe(2)O(10) features a 2D indium oxide layer formed by corner- and edge-sharing InO(6) and InO(7) polyhedra with MoO(4) tetrahedra and TeO(n) (n = 4, 5) polyhedra hanging on both sides of the layer, there are weak interlayer Te-O bonds of 2.512 A. Results of optical diffuse reflectance spectrum measurements indicate that all four compounds are insulators, which are in agreement with results of band structure calculations based on DFT methods.

TeV e+e- linear colliders

International Nuclear Information System (INIS)

Le Duff, J.

1987-12-01

The basic philosophy and performance and technical constraints of linear e + e - colliders at TeV energies are summarized. Collider luminosity, pinch effects due to beam interaction, beam-beam bremsstrahlung, and typical parameters for an e + e - linear collider are discussed. Accelerating structures, HF power sources, electron guns, positron production, and storage rings are considered [fr

Susy seesaw inflation and NMSO(10)GUT

International Nuclear Information System (INIS)

Aulakh, Charanjit S.

2013-01-01

We show that Supersymmetric models with Type I seesaw neutrino masses support slow roll inflection point inflation. The inflaton is the D-flat direction labelled by the chiral invariant HLN composed of the Higgs(H), slepton(L) and conjugate sneutrino(N) superfields. The scale of inflation and fine tuning is set by the conjugate neutrino Majorana mass M ν c ∼ 10 6 - 10 12 GeV. The cubic term in the (quartic) inflaton potential is dominantly from superpotential (not soft Susy breaking) couplings. The tuning conditions are thus insensitive to soft supersymmetry breaking parameters and are generically much less stringent than for previous 'A-term' inflation scenarios controlled by mass scales ∼TeV. WMAP limits on the ratio of tensor to scalar perturbations limit the scale M controlling inflection point inflation: M 13 GeV. 'Instant preheating' is operative and dumps the inflaton energy into MSSM modes giving a high reheat temperature: T rh ≈M ν c (3/4) 10 6 GeV ∼ 10 11 - 10 15 GeV. A large gravitino mass > 50 TeV is therefore required to avoid over closure by reheat produced gravitinos. 'Instant preheating' and NLH inflaton facilitate production of right handed neutrinos during inflaton decay and thus non-thermal leptogenesis in addition to thermal leptogenesis. We show that the embedding in the fully realistic New Minimal Supersymmetric SO(10) GUT requires use of the heaviest righthanded neutrino mass as the controlling scale but the possibility of a measurable tensor scalar perturbation ratio seems marginal. We examine the parametric difficulties remaining.

Growth of CrTe thin films by molecular-beam epitaxy

International Nuclear Information System (INIS)

Sreenivasan, M.G.; Hou, X.J.; Teo, K.L.; Jalil, M.B.A.; Liew, T.; Chong, T.C.

2006-01-01

We report the growth of Cr 1-δ Te films on (100) GaAs substrates using ZnTe buffer layers by solid-source molecular-beam epitaxial technique. RHEED patterns indicate a clear structural change during the initial stages of deposition. Temperature-dependent magnetization results reveal that different NiAs-related phases of Cr 1-δ Te can be obtained at different substrate temperatures. By varying the film thickness, a metastable zinc blende structure of CrTe could be obtained at lower substrate temperature

Interface analysis of Ge ultra thin layers intercalated between GaAs substrates and oxide stacks

Energy Technology Data Exchange (ETDEWEB)

Molle, Alessandro, E-mail: alessandro.molle@mdm.infm.i [Laboratorio Nazionale MDM, CNR-INFM, Via C. Olivetti 2, 20041 Agrate Brianza (Italy); Lamagna, Luca; Spiga, Sabina [Laboratorio Nazionale MDM, CNR-INFM, Via C. Olivetti 2, 20041 Agrate Brianza (Italy); Fanciulli, Marco [Laboratorio Nazionale MDM, CNR-INFM, Via C. Olivetti 2, 20041 Agrate Brianza (MI) (Italy); Dipartimento di Scienza dei Materiali, Universita di Milano Bicocca, Milano (Italy); Brammertz, Guy; Meuris, Marc [IMEC, 75 Kapeldreef, B-3001 Leuven (Belgium)

2010-01-01

Capping III-V compound surfaces with Ge ultra-thin layer might be a viable pathway to passivate the electrically active interface traps which usually jeopardize the integration of III-V materials in metal-oxide-semiconductor devices. As the physical nature of such traps is intrinsically related to the chemical details of the interface composition, the structural and compositional features of the Ge/GaAs interface were thoroughly investigated in two different configurations, the atomic layer deposition of La-doped ZrO{sub 2} films on Ge-capped GaAs and the ultra-high vacuum based molecular beam deposition of GeO{sub 2}/Ge double stack on in situ prepared GaAs. In the former case, the intercalation of a Ge interface layer is shown to suppress the concentration of interface Ga-O, As-O and elemental As bonding which were significantly detected in case of the direct oxide deposition on GaAs. In the latter case, the incidence of two different in situ surface preparations, the Ar sputtering and the atomic H cleaning, on the interface composition is elucidated and the beneficial role played by the atomic H exposure in reducing the semiconductor-oxygen bonds at the interface level is demonstrated.

Proton GE/GM from beam-target asymmetry

International Nuclear Information System (INIS)

Mark Jones; Aram Aghalaryan; Abdellah Ahmidouch; Razmik Asaturyan; Frederic Bloch; Werner Boeglin; Peter Bosted; Cedric Carasco; Roger Carlini; Jinseok Cha; Jian-Ping Chen; Michael Christy; Leon Cole; Luminita Coman; Donald Crabb; Samuel Danagoulian; Donal Day; James Dunne; Mostafa Elaasar; Rolf Ent; Howard Fenker; Emil Frlez; David Gaskell; Liping Gan; Javier Gomez; Bitao Hu; Juerg Jourdan; Christopher Keith; Cynthia Keppel; Mahbubul Khandaker; Andreas Klein; Laird Kramer; Yongguang Liang; Jechiel Lichtenstadt; Richard Lindgren; David Mack; Paul McKee; Dustin McNulty; David Meekins; Hamlet Mkrtchyan; Rakhsha Nasseripour; Maria-Ioana Niculescu; Kristoff Normand; Blaine Norum; Dinko Pocanic; Yelena Prok; Brian Raue; Joerg Reinhold; Julie Roche; Daniela Rohe; Oscar Rondon-Aramayo; Nikolai Savvinov; Bradley Sawatzky; Mikell Seely; Ingo Sick; Karl Slifer; C. Smith; Gregory Smith; S. Stepanyan; Liguang Tang; Shigeyuki Tajima; Giuseppe Testa; William Vulcan; Kebin Wang; Glen Warren; Frank Wesselmann; Stephen Wood; Chen Yan; Lulin Yuan; Junho Yun; Markus Zeier; Hong Guo Zhu

2006-01-01

The ratio of the proton's electric to magnetic form factor, G E /G M , can be extracted in elastic electron-proton scattering by measuring either cross sections, beam-target asymmetry or recoil polarization. Separate determinations of G E /G M by cross sections and recoil polarization observables disagree for Q 2 > 1 (GeV/c) 2 . Measurement by a third technique might uncover an unknown systematic error in either of the previous measurements. The beam-target asymmetry has been measured for elastic electron-proton scattering at Q 2 = 1.51 (GeV/c) 2 for target spin orientation aligned perpendicular to the beam momentum direction. This is the largest Q 2 at which G E /G M has been determined by a beam-target asymmetry experiment. The result, μG E /G M = 0.884 +/- 0.027 +/- 0.029, is compared to previous world data

Antideuteron production in Upsilon(nS) decays and in e(+)e(-) -> q(q) over bar at root s approximate to 10.58 GeV

NARCIS (Netherlands)

Lees, J. P.; Poireau, V.; Tisserand, V.; Grauges, E.; Palano, A.; Eigen, G.; Stugu, B.; Brown, D. N.; Kerth, L. T.; Kolomensky, Yu. G.; Lynch, G.; Schroeder, T.; Hearty, C.; Mattison, T. S.; McKenna, J. A.; So, R. Y.; Khan, A.; Blinov, V. E.; Buzykaev, A. R.; Druzhinin, V. P.; Golubev, V. B.; Kravchenko, E. A.; Onuchin, A. P.; Serednyakov, S. I.; Skovpen, Yu. I.; Solodov, E. P.; Todyshev, K. Yu.; Lankford, A. J.; Mandelkern, M.; Dey, B.; Gary, J. W.; Long, O.; Campagnari, C.; Sevilla, M. Franco; Hong, T. M.; Kovalskyi, D.; Richman, J. D.; West, C. A.; Eisner, A. M.; Lockman, W. S.; Vazquez, W. Panduro; Schumm, B. A.; Seiden, A.; Chao, D. S.; Echenard, B.; Flood, K. T.; Hitlin, D. G.; Miyashita, T. S.; Ongmongkolkul, P.; Andreassen, R.; Huard, Z.; Meadows, B. T.; Pushpawela, B. G.; Sokoloff, M. D.; Sun, L.; Bloom, P. C.; Ford, W. T.; Gaz, A.; Smith, J. G.; Wagner, S. R.; Ayad, R.; Toki, W. H.; Spaan, B.; Bernard, D.; Verderi, M.; Playfer, S.; Bettoni, D.; Bozzi, C.; Calabrese, R.; Cibinetto, G.; Fioravanti, E.; Garzia, I.; Luppi, E.; Piemontese, L.; Santoro, V.; Calcaterra, A.; de Sangro, R.; Finocchiaro, G.; Martellotti, S.; Patteri, P.; Peruzzi, I. M.; Piccolo, M.; Rama, M.; Zallo, A.; Contri, R.; Lo Vetere, M.; Monge, M. R.; Passaggio, S.; Patrignani, C.; Robutti, E.; Bhuyan, B.; Prasad, V.; Morii, M.; Adametz, A.; Uwer, U.; Lacker, H. M.; Dauncey, P. D.; Mallik, U.; Cochran, J.; Prell, S.; Ahmed, H.; Gritsan, A. V.; Arnaud, N.; Davier, M.; Derkach, D.; Grosdidier, G.; Le Diberder, F.; Lutz, A. M.; Malaescu, B.; Roudeau, P.; Stocchi, A.; Wormser, G.; Lange, D. J.; Wright, D. M.; Coleman, J. P.; Fry, J. R.; Gabathuler, E.; Hutchcroft, D. E.; Payne, D. J.; Touramanis, C.; Bevan, A. J.; Di Lodovico, F.; Sacco, R.; Cowan, G.; Bougher, J.; Brown, D. N.; Davis, C. L.; Denig, A. G.; Fritsch, M.; Gradl, W.; Griessinger, K.; Hafner, A.; Prencipe, E.; Schubert, K. R.; Barlow, R. J.; Lafferty, G. D.; Cenci, R.; Hamilton, B.; Jawahery, A.; Roberts, D. A.; Cowan, R.; Sciolla, G.; Cheaib, R.; Patel, P. M.; Robertson, S. H.; Neri, N.; Palombo, F.; Cremaldi, L.; Godang, R.; Sonnek, P.; Summers, D. J.; Simard, M.; Taras, P.; De Nardo, G.; Onorato, G.; Sciacca, C.; Martinelli, M.; Raven, G.; Jessop, C. P.; LoSecco, J. M.; Honscheid, K.; Kass, R.; Feltresi, E.; Margoni, M.; Morandin, M.; Posocco, M.; Rotondo, M.; Simi, G.; Simonetto, F.; Stroili, R.; Akar, S.; Ben-Haim, E.; Bomben, M.; Bonneaud, G. R.; Briand, H.; Calderini, G.; Chauveau, J.; Leruste, Ph.; Marchiori, G.; Ocariz, J.; Sitt, S.; Biasini, M.; Manoni, E.; Pacetti, S.; Rossi, A.; Angelini, C.; Batignani, G.; Bettarini, S.; Carpinelli, M.; Casarosa, G.; Cervelli, A.; Chrzaszcz, M.; Forti, F.; Giorgi, M. A.; Lusiani, A.; Oberhof, B.; Paoloni, E.; Perez, A.; Rizzo, G.; Walsh, J. J.; Pegna, D. Lopes; Olsen, J.; Smith, A. J. S.; Faccini, R.; Ferrarotto, F.; Ferroni, F.; Gaspero, M.; Gioi, L. Li; Piredda, G.; Buenger, C.; Dittrich, S.; Gruenberg, O.; Leddig, T.; Voss, C.; Waldi, R.; Adye, T.; Olaiya, E. O.; Wilson, F. F.; Emery, S.; Vasseur, G.; Anulli, F.; Aston, D.; Bard, D. J.; Cartaro, C.; Convery, M. R.; Dorfan, J.; Dubois-Felsmann, G. P.; Dunwoodie, W.; Ebert, M.; Field, R. C.; Fulsom, B. G.; Graham, M. T.; Hast, C.; Innes, W. R.; Kim, P.; Leith, D. W. G. S.; Lewis, P.; Lindemann, D.; Luitz, S.; Luth, V.; Lynch, H. L.; MacFarlane, D. B.; Muller, D. R.; Neal, H.; Perl, M.; Pulliam, T.; Ratcliff, B. N.; Roodman, A.; Salnikov, A. A.; Schindler, R. H.; Snyder, A.; Su, D.; Sullivan, M. K.; Va'vra, J.; Wisniewski, W. J.; Wulsin, H. W.; Purohit, M. V.; White, R. M.; Wilson, J. R.; Randle-Conde, A.; Sekula, S. J.; Bellis, M.; Burchat, P. R.; Puccio, E. M. T.; Alam, M. S.; Ernst, J. A.; Gorodeisky, R.; Guttman, N.; Peimer, D. R.; Soffer, A.; Spanier, S. M.; Ritchie, J. L.; Ruland, A. M.; Schwitters, R. F.; Wray, B. C.; Izen, J. M.; Lou, X. C.; Bianchi, F.; De Mori, F.; Filippi, A.; Gamba, D.; Lanceri, L.; Vitale, L.; Martinez-Vidal, F.; Oyanguren, A.; Villanueva-Perez, P.; Albert, J.; Banerjee, Sw.; Beaulieu, A.; Bernlochner, F. U.; Choi, H. H. F.; Kowalewski, R.; Lewczuk, M. J.; Lueck, T.; Nugent, I. M.; Roney, J. M.; Sobie, R. J.; Tasneem, N.; Gershon, T. J.; Harrison, P. F.; Latham, T. E.; Band, H. R.; Dasu, S.; Pan, Y.; Prepost, R.

2014-01-01

We present measurements of the inclusive production of antideuterons in e+e− annihilation into hadrons at ≈10.58  GeV center-of-mass energy and in Υ(1S,2S,3S) decays. The results are obtained using data collected by the BABAR detector at the PEP-II electron-positron collider. Assuming a fireball

Studies on the preparation of {sup 68}Ge-{sup 68}Ga generator with inorganic materials

Energy Technology Data Exchange (ETDEWEB)

Brambilla, Tania P.; Osso Junior, Joao A., E-mail: jaosso@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

{sup 68}Ga as a positron emitter is of great interest because of some important advantages. It has a physical half-life of 67.71 min, which is compatible with the pharmacokinetics of many radiopharmaceuticals of low molecular weight. Other important characteristic is its cyclotron-independent availability via the {sup 68}Ge-{sup 68}Ga radionuclide generator system. In Brazil only one positron emitter radionuclide is produced, {sup 18}F, and the medical class has a great interest in using {sup 68}Ga labeled molecules, in particular peptides such as DOTA-octriotide. A project for developing a home made {sup 68}Ge-{sup 68}Ga is under way at IPEN-CNEN/SP. The aim of this work is to develop an efficient and simplified generator system of {sup 68}Ge-{sup 68}Ga that offers {sup 68}Ga{sup 3+} adequate for clinical use. Initial results will be reported concerning the behavior of Ge and Ga in adsorbers such as calcined acid and basic Al{sub 2}O{sub 3}, HZO (hydrous zirconium oxide), TiO{sub 2}, microspheres of Zr (Zr mic) and microspheres of Al (Al mic). Adsorption studies were carried out using {gamma}-emitting tracers, {sup 67}Ga and {sup 68}Ga and chemical tracer, GeO{sub 2}. The samples containing {sup 67}/{sup 68}Ga were analysed using a dose calibrator CRC-15R from Capintec and the samples containing Ge were evaluated by the Optical Emission Spectrometry using Inductively Coupled Plasma (ICP-OES). The ICP-OES equipment used was a Varian Vista-MPX from Varian and calibration curves for Ge were constructed in the range of 0.2 to 1.0 {mu}g.mL{sup -1}. The use of basic Al{sub 2}O{sub 3}, TiO{sub 2}, HZO and Zr mic showed the more promising results. (author)

THE FIRST FERMI-LAT CATALOG OF SOURCES ABOVE 10 GeV

International Nuclear Information System (INIS)

Ackermann, M.; Buehler, R.; Ajello, M.; Allafort, A.; Bechtol, K.; Bloom, E. D.; Atwood, W. B.; Belfiore, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bregeon, J.; Bernieri, E.; Bissaldi, E.; Bonamente, E.; Brandt, T. J.; M. Merlin dell'Università e del Politecnico di Bari, I-70126 Bari (Italy))" data-affiliation=" (Dipartimento di Fisica M. Merlin dell'Università e del Politecnico di Bari, I-70126 Bari (Italy))" >Brigida, M.; Bruel, P.

2013-01-01

We present a catalog of γ-ray sources at energies above 10 GeV based on data from the Large Area Telescope (LAT) accumulated during the first 3 yr of the Fermi Gamma-ray Space Telescope mission. The first Fermi-LAT catalog of >10 GeV sources (1FHL) has 514 sources. For each source we present location, spectrum, a measure of variability, and associations with cataloged sources at other wavelengths. We found that 449 (87%) could be associated with known sources, of which 393 (76% of the 1FHL sources) are active galactic nuclei. Of the 27 sources associated with known pulsars, we find 20 (12) to have significant pulsations in the range >10 GeV (>25 GeV). In this work we also report that, at energies above 10 GeV, unresolved sources account for 27% ± 8% of the isotropic γ-ray background, while the unresolved Galactic population contributes only at the few percent level to the Galactic diffuse background. We also highlight the subset of the 1FHL sources that are best candidates for detection at energies above 50-100 GeV with current and future ground-based γ-ray observatories

High thermoelectric potential of Bi{sub 2}Te{sub 3} alloyed GeTe-rich phases

Energy Technology Data Exchange (ETDEWEB)

Madar, Naor; Givon, Tom; Mogilyansky, Dmitry; Gelbstein, Yaniv [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva (Israel)

2016-07-21

In an attempt to reduce our reliance on fossil fuels, associated with severe environmental effects, the current research is focused on the identification of the thermoelectric potential of p-type (GeTe){sub 1−x}(Bi{sub 2}Te{sub 3}){sub x} alloys, with x values of up to 20%. Higher solubility limit of Bi{sub 2}Te{sub 3} in GeTe, than previously reported, was identified around ∼9%, extending the doping potential of GeTe by the Bi{sub 2}Te{sub 3} donor dopant, for an effective compensation of the high inherent hole concentration of GeTe toward thermoelectrically optimal values. Around the solubility limit of 9%, an electronic optimization resulted in an impressive maximal thermoelectric figure of merit, ZT, of ∼1.55 at ∼410 °C, which is one of the highest ever reported for any p-type GeTe-rich alloys. Beyond the solubility limit, a Fermi Level Pinning effect of stabilizing the Seebeck coefficient was observed in the x = 12%–17% range, leading to stabilization of the maximal ZTs over an extended temperature range; an effect that was associated with the potential of the governed highly symmetric Ge{sub 8}Bi{sub 2}Te{sub 11} and Ge{sub 4}Bi{sub 2}Te{sub 7} phases to create high valence band degeneracy with several bands and multiple hole pockets on the Fermi surface. At this compositional range, co-doping with additional dopants, creating shallow impurity levels (in contrast to the deep lying level created by Bi{sub 2}Te{sub 3}), was suggested for further electronic optimization of the thermoelectric properties.

Epitaxial growth of Ge-Sb-Te based phase change materials

International Nuclear Information System (INIS)

Perumal, Karthick

2013-01-01

Ge-Sb-Te based phase change materials are considered as a prime candidate for optical and electrical data storage applications. With the application of an optical or electrical pulse, they can be reversibly switched between amorphous and crystalline state, thereby exhibiting large optical and electrical contrast between the two phases, which are then stored as information in the form of binary digits. Single crystalline growth is interesting from both the academic and industrial perspective, as ordered Ge-Sb-Te based metamaterials are known to exhibit switching at reduced energies. The present study deals with the epitaxial growth and analysis of Ge-Sb-Te based thin films. The first part of the thesis deals with the epitaxial growth of GeTe. Thin films of GeTe were grown on highly mismatched Si(111) and (001) substrates. On both the substrate orientations the film grows along [111] direction with an amorphous-to-crystalline transition observed during the initial stages of growth. The amorphous-to-crystalline transition was studied in-vivo using azimuthal reflection high-energy electron diffraction scans and grazing incidence X-ray diffraction. In the second part of the thesis epitaxy and characterization of Sb 2 Te 3 thin films are presented. The third part of the thesis deals with the epitaxy of ternary Ge-Sb-Te alloys. The composition of the films are shown to be highly dependent on growth temperatures and vary along the pseudobinary line from Sb 2 Te 3 to GeTe with increase in growth temperatures. A line-of-sight quadrupole mass spectrometer was used to reliably control the GeSbTe growth temperature. Growth was performed at different Ge, Sb, Te fluxes to study the compositional variation of the films. Incommensurate peaks are observed along the [111] direction by X-ray diffraction. The possibility of superstructural vacancy ordering along the [111] direction is discussed.

Structure and Stability of GeAun, n = 1-10 clusters: A Density Functional Study

International Nuclear Information System (INIS)

Priyanka,; Dharamvir, Keya; Sharma, Hitesh

2011-01-01

The structures of Germanium doped gold clusters GeAu n (n = 1-10) have been investigated using ab initio calculations based on density functional theory (DFT). We have obtained ground state geometries of GeAu n clusters and have it compared with Silicon doped gold clusters and pure gold clusters. The ground state geometries of the GeAu n clusters show patterns similar to silicon doped gold clusters except for n = 5, 6 and 9. The introduction of germanium atom increases the binding energy of gold clusters. The binding energy per atom of germanium doped cluster is smaller than the corresponding silicon doped gold cluster. The HUMO-LOMO gap for Au n Ge clusters have been found to vary between 0.46 eV-2.09 eV. The mullikan charge analysis indicates that charge of order of 0.1e always transfers from germanium atom to gold atom.

High performance Ω-gated Ge nanowire MOSFET with quasi-metallic source/drain contacts.

Science.gov (United States)

Burchhart, T; Zeiner, C; Hyun, Y J; Lugstein, A; Hochleitner, G; Bertagnolli, E

2010-10-29

Ge nanowires (NWs) about 2 µm long and 35 nm in diameter are grown heteroepitaxially on Si(111) substrates in a hot wall low-pressure chemical vapor deposition (LP-CVD) system using Au as a catalyst and GeH(4) as precursor. Individual NWs are contacted to Cu pads via e-beam lithography, thermal evaporation and lift-off techniques. Self-aligned and atomically sharp quasi-metallic copper-germanide source/drain contacts are achieved by a thermal activated phase formation process. The Cu(3)Ge segments emerge from the Cu contact pads through axial diffusion of Cu which was controlled in situ by SEM, thus the active channel length of the MOSFET is adjusted without any restrictions from a lithographic process. Finally the conductivity of the channel is enhanced by Ga(+) implantation leading to a high performance Ω-gated Ge-NW MOSFET with saturation currents of a few microamperes.

Influence of Ce-H bonding on the physical properties of the hydrides CeCoSiH1.0 and CeCoGeH1.0

International Nuclear Information System (INIS)

Chevalier, B; Matar, S F; Menetrier, M; Marcos, J Sanchez; Fernandez, J Rodriguez

2006-01-01

The hydrides CeCoSiH 1.0 and CeCoGeH 1.0 which crystallize like the parent antiferromagnetic compounds CeCoSi and CeCoGe in the tetragonal CeFeSi-type structure, have been investigated by specific heat and thermoelectric power measurements and 1 H nuclear magnetic resonance (NMR). CeCoSiH 1.0 is an intermediate valence compound whereas CeCoGeH 1.0 can be considered as a nearly trivalent cerium compound. This behaviour is corroborated by the occurrence of a slight broadening of the 1 H NMR signal in the sequence CeCoSiH 1.0 → CeCoGeH 1.0 . The band structure calculations performed on these hydrides reveal the existence of strong bonding Ce-H interaction, found to be larger in CeCoSiH 1.0 than in CeCoGeH 1.0

Fabrication and Characterization of novel W80Ni10Nb10 alloy produced by mechanical alloying

Science.gov (United States)

Saxena, R.; Patra, A.; Karak, S. K.; Pattanaik, A.; Mishra, S. C.

2016-02-01

Nanostructured tungsten (W) based alloy with nominal composition of W80Ni10Nb10 (in wt. %) was synthesized by mechanical alloying of elemental powders of tungsten (W), nickel (Ni), niobium (Nb) in a high energy planetary ball-mill for 20 h using chrome steel as grinding media and toluene as process control agent followed by compaction at 500 MPa pressure for 5 mins and sintering at 1500°C for 2 h in Ar atmosphere. The phase evolution and the microstructure of the milled powder and consolidated product were investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The crystallite size of W in W80Ni10Nb10 powder was reduced from 100 μm at 0 h to 45.6 nm at 10 h and 34.1 nm at 20 h of milling whereas lattice strain increases to 35% at 20 h of milling. The dislocation density shows sharp increase up to 5 h of milling and the rate of increase drops beyond 5 to 20 h of milling. The lattice parameter of tungsten in W80Ni10Nb10 expanded upto 0.04% at 10 h of milling and contracted upto 0.02% at 20 h of milling. The SEM micrograph revealed the presence of spherical and elongated particles in W80Ni10Nb10 powders at 20 h of milling. The particle size decreases from 100 μm to 2 μm with an increase in the milling time from 0 to 20 hours. The crystallite size of W in milled W80Ni10Nb10 alloy as evident from bright field TEM image was in well agreement with the measured crystallite size from XRD. Structure of W in 20 h milled W80Ni10Nb10 alloy was identified by indexing of selected area diffraction (SAD) pattern. Formation of NbNi intermetallic was evident from XRD pattern and SEM micrograph of sintered alloy. Maximum sinterability of 90.8% was achieved in 20 h milled sintered alloy. Hardness and wear study was also conducted to investigate the mechanical behaviour of the sintered product. Hardness of W80Ni10Nb10 alloy reduces with increasing load whereas wear rate increases with increasing load. The evaluated

21 CFR 80.10 - Fees for certification services.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Fees for certification services. 80.10 Section 80.10 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL COLOR...) Method of payment. All deposits and fees required by this section shall be paid by money order, bank...

Recent study for multibaryon states with strangeness in pC interaction at 10 GeV/c

Energy Technology Data Exchange (ETDEWEB)

Aslanyan, P. Zh., E-mail: paslanian@jinr.ru [Joint Institute for Nuclear Research (Russian Federation)

2013-08-15

Strange multibaryon states with {Lambda}-hyperon and K{sub s}{sup 0} -meson subsystems has been studied from 700 000 stereo photographs or 10{sup 6} inelastic interactions which was obtained from expose of 2-m propane bubble chamber (PBC) LHEP, JINR to proton beams at 10 GeV/c. The obtained results from PBC can be divided into three subjects: in-medium effects of hadronic particles; baryon spectroscopy; hyper-nucleus production. At present the experimental situation is confused; so is theory. New accelerator research complexes has unique possibility for high-statistic and 4{pi}-geometry study of exotic states.

Searches for the Anomalous FCNC Top-Higgs Couplings with Polarized Electron Beam at the LHeC

Directory of Open Access Journals (Sweden)

XiaoJuan Wang

2017-01-01

Full Text Available We study the single top and Higgs associated production e-p→νet-→νehq-(h→bb- in the top-Higgs FCNC couplings at the LHeC with the electron beam energy of Ee=60 GeV and Ee=120 GeV and combination of a 7 TeV and 50 TeV proton beam. With the possibility of e-beam polarization (pe=0, ±0.6, we distinct the cut-based method and the multivariate analysis- (MVA- based method and compare with the current experimental and theoretical limits. It is shown that the branching ratio Br(t→uh can be probed to 0.113 (0.093%, 0.071 (0.057%, 0.030 (0.022%, and 0.024 (0.019% with the cut-based (MVA-based analysis at (Ep, Ee = (7 TeV, 60 GeV, (Ep, Ee = (7 TeV, 120 GeV, (Ep, Ee = (50 TeV, 60 GeV, and (Ep, Ee = (50 TeV, 120 GeV beam energy and 1σ level. With the possibility of e-beam polarization, the expected limits can be probed down to 0.090 (0.073%, 0.056 (0.045%, 0.024 (0.018%, and 0.019 (0.015%, respectively.

The excess enthalpies of liquid Ge-Pb-Te alloys

International Nuclear Information System (INIS)

Blachnik, R.; Binder, J.; Schlieper, A.

1997-01-01

The excess enthalpies of liquid alloys in the ternary system Ge-Pb-Te were determined at 1210 K in a heat flow calorimeter for five sections Ge y Pb 1-y -Te with y = 0.2, 0.4, 0.5, 0.6 and 0.8 and at 1153 K for Ge 0.5 Pb 0.5 -Te. The enthalpy surface in the ternary system is determined by a valley of exothermic minima, stretching from an exothermic minimum at the composition GeTe to one at the composition PbTe in the respective binaries. The excess enthalpies in the limiting metallic binary were adapted with the Redlich-Kister formalism. For the description of the thermodynamic functions in the ternary system the equation of Bonnier was taken using ternary coefficients. The calculated curves are in good agreement with the experimental data. (orig.)

Epitaxial growth of Ge-Sb-Te based phase change materials

Energy Technology Data Exchange (ETDEWEB)

Perumal, Karthick

2013-07-30

Ge-Sb-Te based phase change materials are considered as a prime candidate for optical and electrical data storage applications. With the application of an optical or electrical pulse, they can be reversibly switched between amorphous and crystalline state, thereby exhibiting large optical and electrical contrast between the two phases, which are then stored as information in the form of binary digits. Single crystalline growth is interesting from both the academic and industrial perspective, as ordered Ge-Sb-Te based metamaterials are known to exhibit switching at reduced energies. The present study deals with the epitaxial growth and analysis of Ge-Sb-Te based thin films. The first part of the thesis deals with the epitaxial growth of GeTe. Thin films of GeTe were grown on highly mismatched Si(111) and (001) substrates. On both the substrate orientations the film grows along [111] direction with an amorphous-to-crystalline transition observed during the initial stages of growth. The amorphous-to-crystalline transition was studied in-vivo using azimuthal reflection high-energy electron diffraction scans and grazing incidence X-ray diffraction. In the second part of the thesis epitaxy and characterization of Sb{sub 2}Te{sub 3} thin films are presented. The third part of the thesis deals with the epitaxy of ternary Ge-Sb-Te alloys. The composition of the films are shown to be highly dependent on growth temperatures and vary along the pseudobinary line from Sb{sub 2}Te{sub 3} to GeTe with increase in growth temperatures. A line-of-sight quadrupole mass spectrometer was used to reliably control the GeSbTe growth temperature. Growth was performed at different Ge, Sb, Te fluxes to study the compositional variation of the films. Incommensurate peaks are observed along the [111] direction by X-ray diffraction. The possibility of superstructural vacancy ordering along the [111] direction is discussed.

Focusing of submicron beams for TeV-scale e+e- linear colliders

International Nuclear Information System (INIS)

Balakin, V.; Alexandrov, V.A.; Mikhailichenko, A.; Floettmann, K.; Peters, F.; Voss, G.; Bharadwaj, V.; Halling, M.; Holt, J.A.; Buon, J.; Jeanjean, J.; LeDiberder, F.; Lepeltier, V.; Puzo, P.; Heimlinger, G.; Settles, R.; Stierlin, U.; Hayano, H.; Ishihara, N.; Nakayama, H.; Oide, K.; Shintake, T.; Takeuchi, Y.; Yamamoto, N.; Bulos, F.; Burke, D.; Field, R.; Hartman, S.; Helm, R.; Irwin, J.; Iverson, R.; Rokni, S.; Roy, G.; Spence, W.; Tenenbaum, P.; Wagner, S.R.; Walz, D.; Williams, S.

1995-01-01

First experimental results from the final focus test beam (FFTB) are reported. The vertical dimension of a 47-GeV electron beam from the SLAC linac has been reduced at the focal point of the FFTB by a demagnification of 320 to a beam height of approximately 70 nm

Microstructure and magnetic behavior of Mn doped GeTe chalcogenide semiconductors based phase change materials

Science.gov (United States)

Adam, Adam Abdalla Elbashir; Cheng, Xiaomin; Abuelhassan, Hassan H.; Miao, Xiang Shui

2017-06-01

Phase-change materials (PCMs) are the most promising candidates to be used as an active media in the universal data storage and spintronic devices, due to their large differences in physical properties of the amorphous-crystalline phase transition behavior. In the present study, the microstructure, magnetic and electrical behaviors of Ge0.94Mn0.06Te thin film were investigated. The crystallographic structure of Ge0.94Mn0.06Te thin film was studied sing X-ray diffractometer (XRD) and High Resolution Transmission Electron Microscope (HR-TEM). The XRD pattern showed that the crystallization structure of the film was rhombohedral phase for GeTe with a preference (202) orientation. The HR-TEM image of the crystalline Ge0.94Mn0.06Te thin film demonstrated that, there were two large crystallites and small amorphous areas. The magnetization as a function of the magnetic field analyses of both amorphous and crystalline states showed the ferromagnetic hysteretic behaviors. Then, the hole carriers concentration of the film was measured and it found to be greater than 1021 cm-3 at room temperature. Moreover, the anomalous of Hall Effect (AHE) was clearly observed for the measuring temperatures 5, 10 and 50 K. The results demonstrated that the magnitude of AHE decreased when the temperature was increasing.

On Some Physical Properties of GeSe3-Sb2Se3-ZnSe Thin Films and Their Radiation Response

International Nuclear Information System (INIS)

Hosni, H.M.M.A.

2010-01-01

Thin films of the chalcogenides GeSe 3 , Sb 2 Se 3 , ZnSe, (GeSe 3 )80(Sb 2 Se 3 )20 and (GeSe 3 )70(Sb 2 Se 3 )10(ZnSe)20, are prepared by thermal evaporation onto glass substrates. The effect of ZnSe incorporation with both GeSe 3 , Sb 2 Se 3 results in amorphous (GeSe 3 )70(Sb 2 Se 3 )10(ZnSe)20 composition as obtained from the X-ray analysis. Electrical measurements reveal a decrease in dc activation energy, ΔEdc, and an increase in ac activation energy, ΔEac, for (GeSe 3 )70(Sb 2 Se 3 )10(ZnSe)20 as compared with (GeSe 3 )80(Sb 2 Se 3 )20. Optical energy gap, Eg, and band tail width, Ee, are estimated in UV/VIS spectral region for fresh and γ-irradiated films, revealing a decrease in Eg and an increase in Ee for ZnSe and (GeSe 3 )70(Sb 2 Se 3 )10(ZnSe)20 compositions, with irradiation dose.

Thermal Expansion and Luminescent Properties of Triorthogermanates CaLa2- x Eu x Ge3O10 ( x = 0.0-0.6)

Science.gov (United States)

Lipina, O. A.; Surat, L. L.; Baklanova, Ya. V.; Berger, I. F.; Tyutyunnik, A. P.; Zubkov, V. G.

2018-02-01

Solid solutions CaLa2- x Eu x Ge3O10 ( x = 0.0-0.6, Δ x = 0.1) have been synthesized for the first time. The compounds are isostructural to CaLa2Ge3O10, they crystallize in the monoclinic system, space group P21/ c, Z = 4. The low-temperature X-ray diffraction studies have revealed the strain anisotropy of germanate CaLa2Ge3O10 crystal lattice in the temperature range 80-298 K, and the linear thermal expansion coefficients have been calculated. The optical properties of the activated phases have been studied, and the influence of the dopant concentration and the excitation wavelength on the luminescence characteristics of the synthesized compounds has been established.

Combination of the H1 and ZEUS inclusive cross-section measurements at proton beam energies of 460 GeV and 575 GeV and tests of low Bjorken-x phenomenological models

International Nuclear Information System (INIS)

Belov, Pavel

2013-06-01

A combination is presented of the inclusive neutral current e ± p scattering cross section data collected by the H1 and ZEUS collaborations during the last months of the HERA II operation period with proton beam energies E p of 460 and 575 GeV. The kinematic range of the cross section data covers low absolute four-momentum transfers squared, 1.5 GeV 2 ≤ Q 2 ≤ 110 GeV 2 , small values of Bjorken-x, 2.8.10 -5 ≤ x ≤ 1.5.10 -2 , and high inelasticity y ≤ 0.85. The combination algorithm is based on the method of least squares and takes into account correlations of the systematic uncertainties. The combined data are used in the QCD fits to extract the parton distribution functions. The phenomenological low-x dipole models are tested and parameters of the models are obtained. A good description of the data by the dipole model taking into account the evolution of the gluon distribution is observed. The longitudinal structure function F L is extracted from the combination of the currently used H1 and ZEUS reduced proton beam energy data with previously published H1 nominal proton beam energy data of 920 GeV. A precision of the obtained values of F L is improved at medium Q 2 compared to the published results of the H1 collaboration.

Positron beam study of indium tin oxide films on GaN

International Nuclear Information System (INIS)

Cheung, C K; Wang, R X; Beling, C D; Djurisic, A B; Fung, S

2007-01-01

Variable energy Doppler broadening spectroscopy has been used to study open-volume defects formed during the fabrication of indium tin oxide (ITO) thin films grown by electron-beam evaporation on n-GaN. The films were prepared at room temperature, 200 and 300 deg. C without oxygen and at 200 deg. C under different oxygen partial pressures. The results show that at elevated growth temperatures the ITO has fewer open volume sites and grows with a more crystalline structure. High temperature growth, however, is not sufficient in itself to remove open volume defects at the ITO/GaN interface. Growth under elevated temperature and under partial pressure of oxygen is found to further reduce the vacancy type defects associated with the ITO film, thus improving the quality of the film. Oxygen partial pressures of 6 x 10 -3 mbar and above are found to remove open volume defects associated with the ITO/GaN interface. The study suggests that, irrespective of growth temperature and oxygen partial pressure, there is only one type of defect in the ITO responsible for trapping positrons, which we tentatively attribute to the oxygen vacancy

Design of an 18 MW vortex flow water beam dump for 500 GeV electrons/positrons of an international linear collider

International Nuclear Information System (INIS)

Satyamurthy, Polepalle; Rai, Pravin; Tiwari, Vikas; Kulkarni, Kiran; Amann, John; Arnold, Raymond G.; Walz, Dieter; Seryi, Andrei; Davenne, Tristan; Caretta, Ottone; Densham, Chris; Appleby, Robert B.

2012-01-01

Beam dumps are essential components of any accelerator system. They are usually located at the end of the beam delivery systems and are designed to safely absorb and dissipate the particle energy. In the second stage of the proposed International Linear Collider (ILC), the electron and positron beams are accelerated to 500 GeV each (1 TeV total). Each bunch will have 2×10 10 electrons/positrons, and 2820 bunches form one beam bunch train with time duration of 0.95 ms and 4 Hz frequency. The average beam power will be 18 MW with a peak power of 4.5 GW. The FLUKA code was used to determine the power deposited by the beam at all critical locations. This data forms the input into the thermal hydraulic analysis CFD code for detailed flow and thermal evaluation. Both 2D and 3D flow analyses were carried out at all the critical regions to arrive at optimum geometry and flow parameters of the beam dump. The generation and propagation of pressure waves due to rapid deposition of heat has also been analyzed.

GeTe sequences in superlattice phase change memories and their electrical characteristics

Energy Technology Data Exchange (ETDEWEB)

Ohyanagi, T., E-mail: ohyanagi@leap.or.jp; Kitamura, M.; Takaura, N. [Low-Power Electronics Association and Projects (LEAP), Onogawa 16-1, Tsukuba, Ibaraki 305-8569 (Japan); Araidai, M. [Department of Computational Science and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kato, S. [Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571 (Japan); Shiraishi, K. [Department of Computational Science and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571 (Japan)

2014-06-23

We studied GeTe structures in superlattice phase change memories (superlattice PCMs) with a [GeTe/Sb{sub 2}Te{sub 3}] stacked structure by X-ray diffraction (XRD) analysis. We examined the electrical characteristics of superlattice PCMs with films deposited at different temperatures. It was found that XRD spectra differed between the films deposited at 200 °C and 240 °C; the differences corresponded to the differences in the GeTe sequences in the films. We applied first-principles calculations to calculate the total energy of three different GeTe sequences. The results showed the Ge-Te-Ge-Te sequence had the lowest total energy of the three and it was found that with this sequence the superlattice PCMs did not run.

Charge reconstruction of the DAMPE Silicon-Tungsten Tracker: A preliminary study with ion beams

Science.gov (United States)

Qiao, Rui; Peng, Wen-Xi; Guo, Dong-Ya; Zhao, Hao; Wang, Huan-Yu; Gong, Ke; Zhang, Fei; Wu, Xin; Azzarello, Phillip; Tykhonov, Andrii; Asfandiyarov, Ruslan; Gallo, Valentina; Ambrosi, Giovanni

2018-04-01

The DArk Matter Particle Explorer (DAMPE) is one of the four satellites within Strategic Pioneer Research Program in Space Science of the Chinese Academy of Science (CAS). DAMPE can detect electrons, photons in a wide energy range (5 GeV to 10 TeV) and ions up to iron (100 GeV to 100 TeV). The silicon-Tungsten Tracker (STK) is one of the four subdetectors in DAMPE, providing photon-electron conversion, track reconstruction and charge identification for ions. An ion beam test was carried out in CERN with 60 GeV/u Lead primary beams. Charge reconstruction and charge resolution of the STK detectors were investigated.

arXiv Charge reconstruction study of the DAMPE Silicon-Tungsten Tracker with ion beams

CERN Document Server

Qiao, Rui; Guo, Dong-Ya; Zhao, Hao; Wang, Huan-Yu; Gong, Ke; Zhang, Fei; Wu, Xin; Azzarello, Phillip; Tykhonov, Andrii; Asfandiyarov, Ruslan; Gallo, Valentina; Ambrosi, Giovanni; Mazziotta, Nicola; De Mitri, Ivan

The DArk Matter Particle Explorer (DAMPE) is one of the four satellites within Strategic Pioneer Research Program in Space Science of the Chinese Academy of Science (CAS). DAMPE can detect electrons, photons in a wide energy range (5 GeV to 10 TeV) and ions up to iron (100GeV to 100 TeV). Silicon-Tungsten Tracker (STK) is one of the four subdetectors in DAMPE, providing photon-electron conversion, track reconstruction and charge identification for ions. Ion beam test was carried out in CERN with 60GeV/u Lead primary beams. Charge reconstruction and charge resolution of STK detectors were investigated.

Attenuation of 10 MeV electron beam energy to achieve low doses does not affect Salmonella spp. inactivation kinetics

International Nuclear Information System (INIS)

Hieke, Anne-Sophie Charlotte; Pillai, Suresh D.

2015-01-01

The effect of attenuating the energy of a 10 MeV electron beam on Salmonella inactivation kinetics was investigated. No statistically significant differences were observed between the D 10 values of either Salmonella 4,[5],12:i:- or a Salmonella cocktail (S. 4,[5],12:i:-, Salmonella Heidelberg, Salmonella Newport, Salmonella Typhimurium, Salmonella) when irradiated with either a non-attenuated 10 MeV eBeam or an attenuated 10 MeV eBeam (~2.9±0.22 MeV). The results show that attenuating the energy of a 10 MeV eBeam to achieve low doses does not affect the inactivation kinetics of Salmonella spp. when compared to direct 10 MeV eBeam irradiation. - Highlights: • 10 MeV eBeam energy was attenuated to 2.9±0.22 MeV using HDPE sheets. • Attenuation of eBeam energy does not affect the inactivation kinetics of Salmonella. • Microbial inactivation is independent of eBeam energy in the range of 3–10 MeV

Cu(InGa)Se{sub 2} absorber formation by in-situ, low-temperature annealing of co-evaporated bilayer (InGa){sub 2}Se{sub 3}/CuSe precursors

Energy Technology Data Exchange (ETDEWEB)

Moon, Kyeongchan; Kim, Woo Kyoung, E-mail: wkim@ynu.ac.kr

2015-12-01

Chalcopyrite Cu(InGa)Se{sub 2} (CIGS) absorbers were fabricated by the formation of bilayer stacked glass/Mo/(InGa){sub 2}Se{sub 3}/CuSe precursors followed by in-situ thermal annealing at 450 °C for approximately 10 min in a vacuum evaporator. The material properties (e.g., crystal orientation, compositional depth profile, and overall composition) and device performance of the resulting CIGS absorbers were compared with those of the CIGS absorbers formed by conventional 1-stage and 3-stage CIGS formation processes at a similar temperature. X-ray diffraction confirmed that the 1-stage co-evaporation and in-situ annealing of the bilayer precursor produced a polycrystalline CIGS absorber without a specific texture, whereas the CIGS absorber formed by the 3-stage process showed a highly (220) preferred orientation. Secondary ion mass spectrometry revealed Ga accumulation at the bottom of CIGS formed by in-situ annealing of the bilayer precursors. The cell efficiency of the device with the CIGS absorber formed by the in-situ, low-temperature (450 °C) annealing of bilayer stacked glass/Mo/(InGa){sub 2}Se{sub 3}/CuSe precursors was comparable to that produced by the conventional 3-stage process at a similar temperature. - Highlights: • Annealing of (InGa){sub 2}Se{sub 3}/CuSe precursors was compared with coevaporation process. • In-situ annealing of (InGa){sub 2}Se{sub 3}/CuSe precursors at 450 °C produced about 9% solar cell. • Ga profile within Cu(InGa)Se{sub 2} depended on process profile during co-evaporation.

Indium-tin-oxide thin film deposited by a dual ion beam assisted e-beam evaporation system

International Nuclear Information System (INIS)

Bae, J.W.; Kim, J.S.; Yeom, G.Y.

2001-01-01

Indium-tin-oxide (ITO) thin films were deposited on polycarbonate (PC) substrates at low temperatures (<90 deg. C) by a dual ion beam assisted e-beam evaporation system, where one gun (gun 1) is facing ITO flux and the other gun (gun 2) is facing the substrate. In this experiment, effects of rf power and oxygen flow rate of ion gun 2 on the electrical and optical properties of depositing ITO thin films were investigated. At optimal deposition conditions, ITO thin films deposited on the PC substrates larger than 20 cmx20 cm showed the sheet resistance of less than 40 Ω/sq., the optical transmittance of above 90%, and the uniformity of about 5%

Sub-0.1 mu m line fabrication by Focused ion beam and columnar structural Se-Ge resist

CERN Document Server

Lee, H Y; Chung, H B

1998-01-01

As a method to enhance the sensitivity (S) of an inorganic resist for focused-ion-beam (FIB), lithography, sub-0.1 mu m patterning properties of a columnar structural alpha-Se sub 7 sub 5 Ge sub 2 sub 5 resist have been investigated using 30 keV low-energy Ga sup + -FIB exposure and CF sub 4 reactive-ion etching (RIE). development. The Se sub 7 sub 5 Ge sub 2 sub 5 thin films were 60 .deg. and 80 .deg. -obliquely deposited on Si substrate and parts of the films were annealed for several minutes at the glass transition temperature (T sub g =approx 220 .deg. C). Columnar structures with the angles of approximately 40 .deg. and 65 .deg. are observed in 60 .deg. and 80 .deg. -obliquely deposited films, respectively, and they disappear after annealing. Despite the disappearance of the columnar structures, a critical decrease in thickness is not observed. For the FIB exposures with a beam diameter of approx 0.1 mu m and around the threshold dose, the negative-type fine patterns with linewidth of about 0.06 approx 0...

Study of thermal properties and the effect of carrier concentration in the ternary compound Ag6Ge10P12

International Nuclear Information System (INIS)

Ahmad, K.A.

1990-01-01

In this work the thermal properties of the ternary semiconducting compounds (Ag6Ge10P12) have been investigated. Single crystal samples prepared by Bridgman technique low temperature cryostat are illustrated which is suitable to control temperature from liquid nitrogen up to room temperature. The work contains theoretical and experimental study on binary and ternary semiconductors. Also it illustrates the experimental results of thermoelectric properties of AG6Ge10P12 samples as well as the calculated effective mass, Fermi energy and their analysis throughout the temperature range between 80-300 K. 3 tabs.; 18 figs.; 57 refs

Third-order nonlinear optical properties of GeSe2-Ga2Se3-PbI2 glasses

International Nuclear Information System (INIS)

Tang Gao; Liu Cunming; Luo Lan; Chen Wei

2010-01-01

The third-order nonlinear optical (NLO) properties of new selenium-based GeSe 2 -Ga 2 Se 3 -PbI 2 glasses have been measured using the optical Kerr effect (OKE) technique, with picosecond and femtosecond laser pulses. The 0.70GeSe 2 -0.15Ga 2 Se 3 -0.15PbI 2 glass has the largest third-order optical nonlinear susceptibility in GeSe 2 -Ga 2 Se 3 -PbI 2 glass system with χ (3) of 5.28x10 12 esu. In addition, the response time of glasses is sub-picosecond, which is predominantly associated with electron cloud. Local structure of the glasses has been identified by using Raman studies, while the origins of the observed nonlinear optical response are discussed. The [Ge(Ga)Se 4 ] tetrahedral and lone-pair electrons from highly polarizable Pb atom in glasses play an important role in enhanced NLO response. These results as well as their good chemical stability indicate that GeSe 2 -Ga 2 Se 3 -PbI 2 glasses are promising materials for photonic applications of third-order nonlinear optical signal processing.

Direct flow in 10.8 GeV/nucleon Au+Au collisions measured in experiment E917 at the AGS

International Nuclear Information System (INIS)

Back, B. B.; Betts, R. R.; Britt, H. C.; Chang, J.; Chang, W. C.; Gillitzer, A.; Henning, W. F.; Hofman, D. J.; Nanal, V.; Wuosmaa, A. H.

1999-01-01

Analysis of directed flow observable for protons and pions from Au+Au collisions at 10.8 GeV/nucleon from experiment E917 at the AGS is presented. Using a Fourier series expansion, the first Fourier component, ν 1 ,was extracted as a function of rapidity for mid-central collisions (17-24%). Clear evidence for positive directed flow is found in the proton data, and a weak, possibly negative directed flow signal is observed for π + and π -

MOCVD growth of CdTe and HgTe on GaAs in a vertical, high-speed, rotating-disc reactor

International Nuclear Information System (INIS)

Tompa, G.S.; Nelson, C.R.; Reinert, P.D.; Saracino, M.A.; Terrill, L.A.; Colter, P.C.

1989-01-01

The metalorganic chemical vapor deposition (MOCVD) growth of CdTe and HgTe on GaAs (111) and (100) substrates in a vertical, high-speed, rotating-disc reactor was investigated. A range of total reactor pressure, carrier gas flow rate, chemical concentrations, deposition temperature, and rotation rate have been investigated in an attempt to optimize growth conditions. Diisopropyltelluride (DIPTe) and Dimethylcadmium (DMCd) were used as growth precursors. Thickness uniformity varies less than +/- 1.5% over 50 mm diameter wafers. Films having FWHM X-ray rocking curves less than 90 arcsec were obtained on GaAs (111) substrates. The films have excellent surface morphology, exhibiting less than 5 x 10 4 cm - 2 orange peel dents which are much-lt 1 μm in size. An elemental mercury source was added to the growth system. Initial results for the growth of HgTe and HgCdTe are discussed

OBSERVATIONS OF HIGH-ENERGY COSMIC-RAY ELECTRONS FROM 30 GeV TO 3 TeV WITH EMULSION CHAMBERS

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, T. [Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara 252-5258 (Japan); Komori, Y. [Faculty of Health and Social Services, Kanagawa University of Human Services, Yokosuka 238-0013 (Japan); Yoshida, K.; Yanagisawa, K. [College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama 337-8570 (Japan); Nishimura, J.; Yamagami, T.; Saito, Y. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara 229-8510 (Japan); Tateyama, N. [Faculty of Engineering, Kanagawa University, Yokohama 221-8686 (Japan); Yuda, T. [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582 (Japan); Wilkes, R. J., E-mail: tadasik-112850@jasper.dti.ne.jp, E-mail: komori-y@kuhs.ac.jp, E-mail: yoshida@shibaura-it.ac.jp, E-mail: nisimura@icrr.u-tokyo.ac.jp, E-mail: tateyama@n.kanagawa-u.ac.jp, E-mail: yuda@icrr.u-tokyo.ac.jp, E-mail: wilkes@u.washington.edu [Department of Physics, University of Washington, Seattle, WA 98195-1560 (United States)

2012-12-01

We have performed a series of cosmic-ray electron observations using balloon-borne emulsion chambers since 1968. While we previously reported the results from subsets of the exposures, the final results of the total exposures up to 2001 are presented here. Our successive experiments have yielded a total exposure of 8.19 m{sup 2} sr day at altitudes of 4.0-9.4 g cm{sup -2}. The performance of the emulsion chambers was examined by accelerator beam tests and Monte Carlo simulations, and the on-board calibrations were carried out by using the flight data. In this work, we present the cosmic-ray electron spectrum in the energy range from 30 GeV to 3 TeV at the top of the atmosphere, which is well represented by a power-law function with an index of -3.28 {+-} 0.10. The observed data can also be interpreted in terms of diffusive propagation models. The evidence of cosmic-ray electrons up to 3 TeV suggests the existence of cosmic-ray electron sources at distances within {approx}1 kpc and times within {approx}1 Multiplication-Sign 10{sup 5} yr ago.

Electronic structure and magnetism of Ge(Sn)TM.sub.x./sub.Te.sub.1-x./sub. (TM = V,Cr,Mn): a first principles study

Czech Academy of Sciences Publication Activity Database

Liu, Y.; Bose, S. K.; Kudrnovský, Josef

2016-01-01

Roč. 6, č. 12 (2016), 1-12, č. článku 125005. ISSN 2158-3226 R&D Projects: GA ČR GA15-13436S Institutional support: RVO:68378271 Keywords : SnTe and GeTe * doping with 3d metals * lattice structure * exchange integrals * Curie temperature * first-priciples study Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.568, year: 2016

Strong field physics and QED experiments with ELI-NP 2×10PW laser beams

Energy Technology Data Exchange (ETDEWEB)

Turcu, I. C. E., E-mail: Edmond.Turcu@eli-np.ro; Balascuta, S., E-mail: Edmond.Turcu@eli-np.ro; Negoita, F., E-mail: Edmond.Turcu@eli-np.ro [National Institute for Physics and Nuclear Engineering, ELI-NP, Str. Reactorului, nr. 30, P.O.Box MG-6, Bucharest-Magurele (Romania); Jaroszynski, D.; McKenna, P. [University of Strathclyde, Scottish Universities Physics Alliance (SUPA), Glasgow G4 0NG, Scotland (United Kingdom)

2015-02-24

The ELI-NP facility will focus a 10 PW pulsed laser beam at intensities of ∼10{sup 23} W/cm{sup 2} for the first time, enabling investigation of the new physical phenomena at the interfaces of plasma, nuclear and particle physics. The electric field in the laser focus has a maximum value of ∼10{sup 15} V/m at such laser intensities. In the ELI-NP Experimental Area E6, we propose the study of Radiation Reaction, Strong Field Quantum Electrodynamics (QED) effects and resulting production of Ultra-bright Sources of Gamma-rays which could be used for nuclear activation. Two powerful, synchronized 10 PW laser beams will be focused in the E6 Interaction Chamber on either gas or solid targets. One 10 PW beam is the Pump-beam and the other is the Probe-beam. The focused Pump beam accelerates the electrons to relativistic energies. The accelerated electron bunches interact with the very high electro-magnetic field of the focused Probe beam. The layout of the experimental area E6 will be presented with several options for the experimental configurations.

X-ray electron spectra of chalcogenide glasses and polycrystalline alloys of Ge-Te and As-Te systems

International Nuclear Information System (INIS)

Panus, V.R.

1990-01-01

Comparative investigation into structures of crystals and glasses in Ge-Te and As-Te two-component systems was conducted. Analysis of x-ray electron spectra of Ge-Te and As-Te systems indicates, that processes of dissociation-association resulting in formation of new structure units occur in telluride melts at synthesis temperatures. Structural chemical composition of binary glass-like alloys of Ge-Te and As-Te systems differs essentially from the one that corresponds to fusibility equilibrium curve. Oxygen doping into tellurium-base glasses results mainly in occurence of structures forecasted due to thermochemical calculation

The System 80+ Standard Plant design control document. Volume 10

International Nuclear Information System (INIS)

1997-01-01

This Design Control Document (DCD) is a repository of information comprising the System 80+trademark Standard Plant Design. The DCD also provides that design-related information to be incorporated by reference in the design certification rule for the System 80+ Standard Plant Design. Applicants for a combined license pursuant to 10 CFR 52 must ensure that the final Design Certification Rule and the associated Statements of Consideration are used when making all licensing decisions relevant to the System 80+ Standard Plant Design. The Design Control Document contains the DCD introduction, The Certified Design Material (CDM) [i.e., ''Tier 1''] and the Approved Design Material (ADM) [i.e., ''Tier 2''] for the System 80+ Standard Plant Design. The CDM includes the following sections: (1) Introductory material; (2) Certified Design Material for System 80+ systems and structures; (3) Certified Design Material for non-system-based aspects of the System 80+ Certified design; (4) Interface requirements; and (5) Site parameters. The ADM, to the extent applicable for the System 80+ Standard Plant Design, includes: (1) the information required for the final safety analysis report under 20 CFR 50.34; (2) other relevant information required by 10 CFR 52.47; and (3) emergency operations guidelines. This volume contains Appendices 6A, 6B, and 6C for section 6 (Engineered Safety Features) of the ADM Design and Analysis. Also, parts 1--5 of section 7 (Instrumentation and Control) of the ADM Design and Analysis are covered. The following information is covered in these parts: introduction; reactor protection system; ESF actuation system; system required for safe shutdown; and safety-related display instrumentation

Structural stability, dynamical stability, thermoelectric properties, and elastic properties of GeTe at high pressure

Science.gov (United States)

Kagdada, Hardik L.; Jha, Prafulla K.; Śpiewak, Piotr; Kurzydłowski, Krzysztof J.

2018-04-01

The stability of GeTe in rhombohedral (R 3 m ), face centred cubic (F m 3 m ), and simple cubic (P m 3 m ) phases has been studied using density functional perturbation theory. The rhombohedral phase of GeTe is dynamically stable at 0 GPa, while F m 3 m and P m 3 m phases are stable at 3.1 and 33 GPa, respectively. The pressure-dependent phonon modes are observed in F m 3 m and P m 3 m phases at Γ and M points, respectively. The electronic and the thermoelectric properties have been investigated for the stable phases of GeTe. The electronic band gap for rhombohedral and F m 3 m phases of GeTe has been observed as 0.66 and 0.17 eV, respectively, while the P m 3 m phase shows metallic behavior. We have used the Boltzmann transport equation under a rigid band approximation and constant relaxation time approximation as implemented in boltztrap code for the calculation of thermoelectric properties of GeTe. The metallic behavior of P m 3 m phase gives a very low value of Seebeck coefficient compared to the other two phases as a function of temperature and the chemical potential μ. It is observed that the rhombohedral phase of GeTe exhibits higher thermoelectric performance. Due to the metallic nature of P m 3 m phase, negligible thermoelectric performance is observed compared to R 3 m and F m 3 m -GeTe. The calculated lattice thermal conductivities are low for F m 3 m -GeTe and high for R 3 m -GeTe. At the relatively higher temperature of 1350 K, the figure of merit ZT is found to be 0.7 for rhombohedral GeTe. The elastic constants satisfy the Born stability criteria for all three phases. The rhombohedral and F m 3 m phases exhibits brittleness and the P m 3 m phase shows ductile nature.

CuGaTe2-CuAlTe2 system

International Nuclear Information System (INIS)

Bodnar', I.V.

2003-01-01

The results of studies on the chemical interaction in the CuGaTe 2 -CuAlTe 2 as well as on the thermal and optical properties of the formed solid solutions are presented. It is shown, that continuous number of solid solutions are formed in the CuGaTe 2 -CuAlTe 2 system, which crystallize in the chalcopyrite structure. The diagram of state of this system is plotted. The thermal expansion of these materials is studied through the dilatometric method. The linear dependence of the thermal expansion coefficient on the composition is established. The concentration dependences of the forbidden zone width diverge from the linearity [ru

n-(CdMgTe/CdTe)/(p-(CdTe/ZnCdTe/ZnTe)/p-GaAs heterostructure diode for photosensor applications

Science.gov (United States)

Yahia, I. S.; AlFaify, S.; Abutalib, M. M.; Chusnutdinow, S.; Wojtowicz, T.; Karczewski, G.; Yakuphanoglu, F.; Al-Bassam, A.; El-Naggar, A. M.; El-Bashir, S. M.

2016-05-01

High quality n-(CdMgTe:I/n-CdTe:I)/(p-CdTe:N/p-ZnCdTe:N/p-ZnTe:N)/p-GaAs heterojunction diodes have been fabricated by molecular beam epitaxial growth. The illumination effect on the complex impedance and conductivity of heterostructure diode was investigated. The illumination intensities were taken up to the 200 mW/cm2 with frequency range of 42 Hz to 1 MHz. The observed real and imaginary parts of the complex impedance were strongly dependent on the illumination frequency. The inverse relation was observed between the illumination intensity and the complex impedance. The relaxation mechanism of the diode was analyzed by the Cole-Cole plots. The radius of the Cole-Cole curve decreases with increasing illumination intensity. This suggests a mechanism of illumination dependent on the relaxation process. It is also found that the conductivity increases linearly with increasing the illumination intensity. We can conclude that the new design heterostructure diode in our work is a good candidate in photodetector and optoelectronic applications.

Thermophysical and Optical Properties of Semiconducting Ga2Te3 Melt

Science.gov (United States)

Li, Chao; Su, Ching-Hua; Lehoczky, Sandor L.; Scripa, Rosalie N.; Ban, Heng

2005-01-01

The majority of bulk semiconductor single crystals are presently grown from their melts. The thermophysical and optical properties of the melts provide a fundamental understanding of the melt structure and can be used to optimize the growth conditions to obtain higher quality crystals. In this paper, we report several thermophysical and optical properties for Ga2Te3 melts, such as electrical conductivity, viscosity, and optical transmission for temperatures ranging from the melting point up to approximately 990 C. The conductivity and viscosity of the melts are determined using the transient torque technique. The optical transmission of the melts is measured between the wavelengths of 300 and 2000 nm by an dual beam reversed-optics spectrophotometer. The measured properties are in good agreement with the published data. The conductivities indicate that the Ga2Te3 melt is semiconductor-like. The anomalous behavior in the measured properties are used as an indication of a structural transformation in the Ga2Te3 melt and discussed in terms of Eyring's and Bachinskii's predicted behaviors for homogeneous melts.

Uniaxially stressed Ge:Ga and Ge:Be

Energy Technology Data Exchange (ETDEWEB)

Dubon, Jr., Oscar Danilo [Univ. of California, Berkeley, CA (United States)

1992-12-01

The application of a large uniaxial stress to p-type Ge single crystals changes the character of both the valence band and the energy levels associated with the acceptors. Changes include the splitting of the fourfold degeneracy of the valence band top and the reduction of the ionization energy of shallow acceptors. In order to study the effect of uniaxial stress on transport properties of photoexcited holes, a variable temperature photo-Hall effect system was built in which stressed Ge:Ga and Ge:Be could be characterized. Results indicate that stress increases the lifetime and Hall mobility of photoexcited holes. These observations may help further the understanding of fundamental physical processes that affect the performance of stressed Ge photoconductors including the capture of holes by shallow acceptors.

Molecular beam deposition of Al2O3 on p-Ge(001)/Ge0.95Sn0.05 heterostructure and impact of a Ge-cap interfacial layer

International Nuclear Information System (INIS)

Merckling, C.; Franquet, A.; Vincent, B.; Vandervorst, W.; Loo, R.; Caymax, M.; Sun, X.; Shimura, Y.; Takeuchi, S.; Nakatsuka, O.; Zaima, S.

2011-01-01

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

Beam loading and emittance growth for a disk-loaded structure scaled to 10 μm

International Nuclear Information System (INIS)

Wilson, P.B.

1982-05-01

Beam loading and transverse emittance growth are studied in a disk-loaded accelerating structure which has been scaled to a wavelength of 10 μm. The resulting limitations on the charge per bunch which can be accelerated in such a scaled structure should provide a crude estimate of the charge per bunch which can be accelerated in a laser driven grating accelerator operating at the same wavelength. For an accelerator 100 m in length delivering an energy of 500 GeV, it is found that the number of particles per bunch that can be accelerated is on the order of 10 5 -10 6

Thermally-induced crystallization behaviour of 80GeSe2–20Ga2Se3 glass as probed by combined X-ray diffraction and PAL spectroscopy

International Nuclear Information System (INIS)

Shpotyuk, O.; Calvez, L.; Petracovschi, E.; Klym, H.; Ingram, A.; Demchenko, P.

2014-01-01

Highlights: • Chalcogenide Ge–Ga–Se glasses were annealed at 380 °C for 10, 25 and 50 h. • Crystallization of glasses during annealing indicates formation of crystals. • Structural changes are described by two-state positron trapping model. • Modification leading to nucleation and fragmentation of free volume of glasses. • The Ge–Ga–Se systems cannot be classified as typical pseudo-binary system. -- Abstract: Crystallization behaviour of 80GeSe 2 –20Ga 2 Se 3 glass caused by thermal annealing at 380 °C for 10, 25 and 50 h are studied using X-ray diffraction and positron annihilation lifetime spectroscopy. It is shown that the structural changes caused by crystallization can be adequately described by positron trapping modes determined within two-state model. The observed changes in defect-related component in the fit of experimental positron lifetime spectra for annealed glasses testifies in a favour of structural fragmentation of larger free volume entities into smaller ones with preceding nucleation in the initial stage of thermal annealing. Because of strong deviation in defect-free bulk positron lifetime from corresponding additive values proper to boundary constituents, the studied glasses cannot be considered as typical representatives of pseudo-binary cut-section

Framework 'interstitial' oxygen in La10(GeO4)5-(GeO5)O2 apatite electrolyte

International Nuclear Information System (INIS)

Pramana, S.S.; White, T.J.

2007-01-01

Oxygen conduction at low temperatures in apatites make these materials potentially useful as electrolytes in solid-oxide fuel cells, but our understanding of the defect structures enabling ion migration is incomplete. While conduction along [001] channels is dominant, considerable inter-tunnel mobility has been recognized. Using neutron powder diffraction of stoichiometric 'La 10 (GeO 4 ) 6 O 3 ', it has been shown that this compound is more correctly described as an La 10 (GeO 4 ) 5- (GeO 5 )O 2 apatite, in which high concentrations of interstitial oxygen reside within the channel walls. It is suggested that these framework interstitial O atoms provide a reservoir of ions that can migrate into the conducting channels of apatite, via a mechanism of inter-tunnel oxygen diffusion that transiently converts GeO 4 tetrahedra to GeO 5 distorted trigonal bipyramids. This structural modification is consistent with known crystal chemistry and may occur generally in oxide apatites. (orig.)

Evaluatie prototype TOP10-21ste eeuw

NARCIS (Netherlands)

Vullings, L.A.E.; Bulens, J.D.; Bregt, A.K.; Knapen, M.J.R.; Lentjes, P.G.; Wit, de A.J.W.; Zeeuw, de C.J.

2001-01-01

De Topografische Dienst Nederland (TDN) wenst haar geo-informatie product "TOP10 vector" te vernieuwen. Als laatste fase in dit vernieuwingsproces is het prototype getest en geëvalueerd aan de op gebruikerseisen van huidige en potentiële gebruikers gebaseerde gebruikersspecificaties.

Electrical studies of Ge4Sb1Te5 devices for memory applications

Science.gov (United States)

Sangeetha, B. G.; Shylashree, N.

2018-05-01

In this paper, the Ge4Sb1Te5 thin film device preparation and electrical studies for memory devices were carried out. The device was deposited using vapor-evaporation technique. RESET to SET state switching was shown using current-voltage characterization. The current-voltage characterization shows the switching between SET to RESET state and it was found that it requires a low energy for transition. Switching between amorphous to crystalline nature was studied using resistance-voltage characteristics. The endurance showed the effective use of this composition for memory device.

Demonstration of β-(Al x Ga1- x )2O3/β-Ga2O3 modulation doped field-effect transistors with Ge as dopant grown via plasma-assisted molecular beam epitaxy

Science.gov (United States)

Ahmadi, Elaheh; Koksaldi, Onur S.; Zheng, Xun; Mates, Tom; Oshima, Yuichi; Mishra, Umesh K.; Speck, James S.

2017-07-01

β-(Al x Ga1- x )2O3/β-Ga2O3 heterostructures were grown via plasma-assisted molecular beam epitaxy. The β-(Al x Ga1- x )2O3 barrier was partially doped by Ge to achieve a two-dimensional electron gas (2DEG) in Ga2O3. The formation of the 2DEG was confirmed by capacitance-voltage measurements. The impact of Ga-polishing on both the surface morphology and the reduction of the unintentionally incorporated Si at the growth interface was investigated using atomic force microscopy and secondary-ion mass spectrometry. Modulation doped field-effect transistors were fabricated. A maximum current density of 20 mA/mm with a pinch-off voltage of -6 V was achieved on a sample with a 2DEG sheet charge density of 1.2 × 1013 cm-2.

Combination of the H1 and ZEUS inclusive cross-section measurements at proton beam energies of 460 GeV and 575 GeV and tests of low Bjorken-x phenomenological models

Energy Technology Data Exchange (ETDEWEB)

Belov, Pavel

2013-06-15

A combination is presented of the inclusive neutral current e{sup {+-}}p scattering cross section data collected by the H1 and ZEUS collaborations during the last months of the HERA II operation period with proton beam energies E{sub p} of 460 and 575 GeV. The kinematic range of the cross section data covers low absolute four-momentum transfers squared, 1.5 GeV{sup 2} {<=} Q{sup 2} {<=} 110 GeV{sup 2}, small values of Bjorken-x, 2.8.10{sup -5} {<=} x {<=} 1.5.10{sup -2}, and high inelasticity y {<=} 0.85. The combination algorithm is based on the method of least squares and takes into account correlations of the systematic uncertainties. The combined data are used in the QCD fits to extract the parton distribution functions. The phenomenological low-x dipole models are tested and parameters of the models are obtained. A good description of the data by the dipole model taking into account the evolution of the gluon distribution is observed. The longitudinal structure function F{sub L} is extracted from the combination of the currently used H1 and ZEUS reduced proton beam energy data with previously published H1 nominal proton beam energy data of 920 GeV. A precision of the obtained values of F{sub L} is improved at medium Q{sup 2} compared to the published results of the H1 collaboration.

Room temperature current-voltage (I-V) characteristics of Ag/InGaN/n-Si Schottky barrier diode

Energy Technology Data Exchange (ETDEWEB)

Erdoğan, Erman, E-mail: e.erdogan@alparslan.edu.tr [Department of Physics, Faculty of Art and Science, Muş Alparslan University, Muş 49250 (Turkey); Kundakçı, Mutlu [Department of Physics, Faculty of Science, Atatürk University, Erzurum 25240 (Turkey)

2017-02-01

Metal-semiconductors (MSs) or Schottky barrier diodes (SBDs) have a significant potential in the integrated device technology. In the present paper, electrical characterization of Ag/InGaN/n-Si Schottky diode have been systematically carried out by simple Thermionic method (TE) and Norde function based on the I-V characteristics. Ag ohmic and schottky contacts are deposited on InGaN/n-Si film by thermal evaporation technique under a vacuum pressure of 1×10{sup −5} mbar. Ideality factor, barrier height and series resistance values of this diode are determined from I-V curve. These parameters are calculated by TE and Norde methods and findings are given in a comparetive manner. The results show the consistency for both method and also good agreement with other results obtained in the literature. The value of ideality factor and barrier height have been determined to be 2.84 and 0.78 eV at room temperature using simple TE method. The value of barrier height obtained with Norde method is calculated as 0.79 eV.

Room temperature current-voltage (I-V) characteristics of Ag/InGaN/n-Si Schottky barrier diode

Science.gov (United States)

Erdoğan, Erman; Kundakçı, Mutlu

2017-02-01

Metal-semiconductors (MSs) or Schottky barrier diodes (SBDs) have a significant potential in the integrated device technology. In the present paper, electrical characterization of Ag/InGaN/n-Si Schottky diode have been systematically carried out by simple Thermionic method (TE) and Norde function based on the I-V characteristics. Ag ohmic and schottky contacts are deposited on InGaN/n-Si film by thermal evaporation technique under a vacuum pressure of 1×10-5 mbar. Ideality factor, barrier height and series resistance values of this diode are determined from I-V curve. These parameters are calculated by TE and Norde methods and findings are given in a comparetive manner. The results show the consistency for both method and also good agreement with other results obtained in the literature. The value of ideality factor and barrier height have been determined to be 2.84 and 0.78 eV at room temperature using simple TE method. The value of barrier height obtained with Norde method is calculated as 0.79 eV.

Characteristics of SnO{sub 2}-based {sup 68}Ge/{sup 68}Ga generator and aspects of radiolabelling DOTA-peptides

Energy Technology Data Exchange (ETDEWEB)

Blois, Erik de; Chan, Ho Sze [Department of Nuclear Medicine, Erasmus MC Rotterdam, Rotterdam (Netherlands); Naidoo, Clive; Prince, Deidre [iThemba Labs, Somerset West, Republic of South Africa (South Africa); Krenning, Eric P. [Department of Nuclear Medicine, Erasmus MC Rotterdam, Rotterdam (Netherlands); Department of Internal Medicine, Erasmus MC Rotterdam, Rotterdam (Netherlands); Breeman, Wouter A.P., E-mail: w.a.p.breeman@erasmusmc.n [Department of Nuclear Medicine, Erasmus MC Rotterdam, Rotterdam (Netherlands)

2011-02-15

Objectives: PET scintigraphy with {sup 68}Ga-labelled analogs is of increasing interest in Nuclear Medicine and performed all over the world. Here we report the characteristics of the eluate of SnO{sub 2}-based {sup 68}Ge/{sup 68}Ga generators prepared by iThemba LABS (Somerset West, South Africa). Three purification and concentration techniques of the eluate for labelling DOTA-TATE and concordant SPE purifications were investigated. Methods: Characteristics of 4 SnO{sub 2}-based generators (range 0.4-1 GBq {sup 68}Ga in the eluate) and several concentration techniques of the eluate (HCl) were evaluated. The elution profiles of SnO{sub 2}-based {sup 68}Ge/{sup 68}Ga generators were monitored, while [HCl] of the eluens was varied from 0.3-1.0 M. Metal ions and sterility of the eluate were determined by ICP. Fractionated elution and concentration of the {sup 68}Ga eluate were performed using anion and cation exchange. Concentrated {sup 68}Ga eluate, using all three concentration techniques, was used for labelling of DOTA-TATE. {sup 68}Ga-DOTA-TATE-containing solution was purified and RNP increased by SPE, therefore also 11 commercially available SPE columns were investigated. Results: The amount of elutable {sup 68}Ga activity varies when the concentration of the eluens, HCl, was varied, while {sup 68}Ge activity remains virtually constant. SnO{sub 2}-based {sup 68}Ge/{sup 68}Ga generator elutes at 0.6 M HCl >100% of the {sup 68}Ga activity at calibration time and {+-}75% after 300 days. Eluate at discharge was sterile and Endotoxins were <0.5 EU/mL, RNP was always <0.01%. Metal ions in the eluate were <10 ppm (in total). Highest desorption for anion purification was obtained with the 30 mg Oasis WAX column (>80%). Highest desorption for cation purification was obtained using a solution containing 90% acetone at increasing molarity of HCl, resulted in a {sup 68}Ga desorption of 68{+-}8%. With all {sup 68}Ge/{sup 68}Ga generators and for all 3 purification methods a

Short-wave infrared barriode detectors using InGaAsSb absorption material lattice matched to GaSb

Energy Technology Data Exchange (ETDEWEB)

Craig, A. P.; Percy, B.; Marshall, A. R. J. [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom); Jain, M. [Amethyst Research Ltd., Kelvin Campus, West of Scotland Science Park, Glasgow G20 0SP (United Kingdom); Wicks, G.; Hossain, K. [Amethyst Research, Inc., 123 Case Circle, Ardmore, Oklahoma 73401 (United States); Golding, T. [Amethyst Research Ltd., Kelvin Campus, West of Scotland Science Park, Glasgow G20 0SP (United Kingdom); Amethyst Research, Inc., 123 Case Circle, Ardmore, Oklahoma 73401 (United States); McEwan, K.; Howle, C. [Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ (United Kingdom)

2015-05-18

Short-wave infrared barriode detectors were grown by molecular beam epitaxy. An absorption layer composition of In{sub 0.28}Ga{sub 0.72}As{sub 0.25}Sb{sub 0.75} allowed for lattice matching to GaSb and cut-off wavelengths of 2.9 μm at 250 K and 3.0 μm at room temperature. Arrhenius plots of the dark current density showed diffusion limited dark currents approaching those expected for optimized HgCdTe-based detectors. Specific detectivity figures of around 7×10{sup 10} Jones and 1×10{sup 10} Jones were calculated, for 240 K and room temperature, respectively. Significantly, these devices could support focal plane arrays working at higher operating temperatures.

Penning-trap Q-value determination of the 71Ga(ν,e−)71Ge reaction using threshold charge breeding of on-line produced isotopes

International Nuclear Information System (INIS)

Frekers, D.; Simon, M.C.; Andreoiu, C.; Bale, J.C.; Brodeur, M.; Brunner, T.; Chaudhuri, A.; Chowdhury, U.; Crespo López-Urrutia, J.R.; Delheij, P.; Ejiri, H.; Ettenauer, S.; Gallant, A.T.; Gavrin, V.; Grossheim, A.; Harakeh, M.N.; Jang, F.; Kwiatkowski, A.A.

2013-01-01

We present a first direct Q-value measurement of the 71 Ga(ν,e − ) 71 Ge reaction using the TITAN mass-measurement facility at ISAC/TRIUMF. The measurements were performed in a Penning trap on neon-like 71 Ga 21+ and 71 Ge 22+ using isobar separation of the on-line produced mother and daughter nuclei through threshold charge breeding in an electron-beam ion trap. In addition, isoionic samples of 71 Ga 21+ and 71 Ge 21+ were stored concurrently in the Penning trap and provided a separate Q-value measurement. Both independent measurements result in a combined Q-value of 233.5±1.2 keV, which is in agreement with the previously accepted Q-value for the ν cross-section calculations. Together with a recent measurement of the ν-response from the excited states in 71 Ge, we conclude that there are no further uncertainties in the nuclear structure, which could remove the persistent discrepancy between the SAGE and GALLEX calibration measurements performed with neutrinos from reactor-produced 51 Cr and 37 Ar sources and the theoretical expectation

The 76Ge(n,p)76Ga reaction and its relevance to searches for the neutrino-less double-beta decay of 76Ge

Science.gov (United States)

Tornow, W.; Bhike, Megha; Fallin, B.; Krishichayan, Fnu

2015-10-01

The 76Ge(n,p)76Ga reaction and the subsequent β decay of 76Ga to 76Ge has been used to excite the 3951.9 keV state of 76Ge, which decays by emission of a 2040.7 keV γ ray. Using HPGe detectors, the associated pulse-height signal may be undistinguishable from the potential signal produced in neutrino-less double-beta decay of 76Ge with its Q-value of 2039.0 keV. In the neutron energy range between 10 and 20 MeV the production cross section of the 2040.7 keV γ ray is approximately 0.1 mb. In the same experiment γ rays of energy 2037.9 keV resulting from the 76Ge(n, γ)77Ge reaction were clearly observed. Adding the 76Ge(n,n' γ)76Ge reaction, which also produces the 2040.7 keV γ ray with a cross section value of the order of 0.1 mb clearly shows that great care has to be taken to eliminate neutron-induced backgrounds in searches for neutrino-less double-beta decay of 76Ge. This work was supported by the U.S. DOE under Grant NO. DE-FG02-97ER41033.

Bromine doping of CdTe and CdMnTe epitaxial layers grown by molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Waag, A. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Scholl, S. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Schierstedt, K. von (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Hommel, D. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Landwehr, G. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Bilger, G. (Zentrum fuer Sonnenenergie und Wasserstoff-Forschung, Stuttgart (Germany))

1993-03-01

We report on the n-type doping of CdTe and CdMnTe with bormine as a novel dopant material. /the thin films were grown by molecular beam epitaxy. ZnBr[sub 2] was used as a source material for the n-type doping. Free carrier concentrations at room temperature of up to 2.8x10[sup 18] cm[sup -3] could be readily obtained for both CdTe as well as CdMnTe thin films with Mn concentrations below 10%. This is to our knowledge the highest value ever obtained for the dilute magnetic semiconductor CdMnTe. For ZnBr[sub 2] source temperatures up to 60 C - corresponding to a free carrier concentration of (2-3)x10[sup 18] cm[sup -3] - the free carrier concentration of the epitaxial film increases with ZnBr[sub 2] source temperature. For higher ZnBr[sub 2] source temperatures compensation becomes dominant, which is indicated by a steep decrease of the free carrier concentration with increasing ZnBr[sub 2] source temperature. In addition the carrier mobility decreases drastically for such high dopant fluxes. A model of bromine incorporation is proposed. (orig.)

Atmospheric and astrophysical Neutrinos above 1 TeV Interacting in IceCube

DEFF Research Database (Denmark)

Aartsen, M.G.; Ackermann, M.; Adam, J.

2015-01-01

The IceCube Neutrino Observatory was designed primarily to search for high-energy (TeV-PeV) neutrinos produced in distant astrophysical objects. A search for ≳100  TeV neutrinos interacting inside the instrumented volume has recently provided evidence for an isotropic flux of such neutrinos...... the energy threshold for neutrinos from the southern sky below 10 TeV for the first time, far below the threshold of the previous high-energy analysis. Astrophysical neutrinos remain the dominant component in the southern sky down to a deposited energy of 10 TeV. From these data we derive new constraints...... on the diffuse astrophysical neutrino spectrum, Φ_ν=2.06_{-0.3}^{+0.4}×10-18(E_ν/10^5  GeV)^{-2.46±0.12} GeV^-1 cm^−2 sr^−1 s^-1 for 25  TeV

P-type Ge epitaxy on GaAs (100) substrate grown by MOCVD

Energy Technology Data Exchange (ETDEWEB)

Jin, Y.J.; Chia, C.K.; Liu, H.F.; Wong, L.M.; Chai, J.W.; Chi, D.Z.; Wang, S.J., E-mail: sj-wang@imre.a-star.edu.sg

2016-07-15

Highlights: • The heterogeneous integration of p-Ge/GaAs by MOCVD indicates significance for the application in optoelectronic devices such as p-MOSFET, dual band photodetector, etc. • Many undesired pillar-structures were observed on the p-Ge epilayers and we found that the cause of the pillar-like structures was related to the Ge-Ga dimers formed during the growth. • We found that a GaAs substrate with fewer Ga or Ge danglings was helpful in suppressing the formation of the unwanted pillar-like structures and thus obtaining high quality p-Ge epilayers. - Abstract: In this work, Ga-doped Geranium (Ge) films have been grown on GaAs (100) substrates by metal-organic chemical vapor deposition (MOCVD). Undesired pillar structures have been observed on the epilayers prepared at relatively lower temperatures. Energy dispersive X-ray spectroscopy (EDX) indicated that the pillars are mainly consisted of Ga atoms, which is totally different from that of the Ge film. It was demonstrated that the pillar structures could be reduced by simply raising the growth temperature while keeping the other growth conditions unchanged. In this regard, the growth mechanism of the pillars was related to the Ge-Ga dimers formed during the growth of p-Ge films. By further studying the influence of a GaAs or Ge buffer layer on the growth of p-Ge layers, we found that the GaAs substrate with lower density of Ga or Ge dangling bonds was helpful in suppressing the formation of the undesired pillar structures.

ReGaTE: Registration of Galaxy Tools in Elixir.

Science.gov (United States)

Doppelt-Azeroual, Olivia; Mareuil, Fabien; Deveaud, Eric; Kalaš, Matúš; Soranzo, Nicola; van den Beek, Marius; Grüning, Björn; Ison, Jon; Ménager, Hervé

2017-06-01

Bioinformaticians routinely use multiple software tools and data sources in their day-to-day work and have been guided in their choices by a number of cataloguing initiatives. The ELIXIR Tools and Data Services Registry (bio.tools) aims to provide a central information point, independent of any specific scientific scope within bioinformatics or technological implementation. Meanwhile, efforts to integrate bioinformatics software in workbench and workflow environments have accelerated to enable the design, automation, and reproducibility of bioinformatics experiments. One such popular environment is the Galaxy framework, with currently more than 80 publicly available Galaxy servers around the world. In the context of a generic registry for bioinformatics software, such as bio.tools, Galaxy instances constitute a major source of valuable content. Yet there has been, to date, no convenient mechanism to register such services en masse. We present ReGaTE (Registration of Galaxy Tools in Elixir), a software utility that automates the process of registering the services available in a Galaxy instance. This utility uses the BioBlend application program interface to extract service metadata from a Galaxy server, enhance the metadata with the scientific information required by bio.tools, and push it to the registry. ReGaTE provides a fast and convenient way to publish Galaxy services in bio.tools. By doing so, service providers may increase the visibility of their services while enriching the software discovery function that bio.tools provides for its users. The source code of ReGaTE is freely available on Github at https://github.com/C3BI-pasteur-fr/ReGaTE . © The Author 2017. Published by Oxford University Press.

Density functional simulations of Sb-rich GeSbTe phase change alloys

OpenAIRE

Gabardi, S; Caravati, S; Bernasconi, M; Parrinello, M

2012-01-01

We generated models of the amorphous phase of Sb rich GeSbTe phase change alloys by quenching from the melt within density functional molecular dynamics. We considered the two compositions Ge 1Sb 1Te 1 and Ge 2Sb 4Te 5. Comparison with previous results on the most studied Ge 2Sb 2Te 5 allowed us to draw some conclusions on the dependence of the structural properties of the amorphous phase on the alloy composition. Vibrational and electronic properties were also scrutinized. Phonons at high fr...

Effect of Ge Addition on the Optical Band Gap and Refractive Index of Thermally Evaporated As2Se3 Thin Films

Directory of Open Access Journals (Sweden)

Pankaj Sharma

2008-01-01

Full Text Available The present paper reports the effect of Ge addition on the optical band gap and refractive index of As2Se3 thin films. Thin films of As2Se3 and (As2Se390Ge10 were prepared by thermal evaporation technique at base pressure 10−4 Pa. Optical band gap and refractive index were calculated by analyzing the transmission spectrum in the spectral range 400–1500 nm. The optical band gap decreases while the refractive index increases with the addition of Ge to As2Se3. The decrease of optical band gap has been explained on the basis of density of states; and the increase in refractive index has been explained on the basis increase in disorder in the system.

An EXAFS spectrometer on beam line 10B at the Photon Factory

International Nuclear Information System (INIS)

Oyanagi, Hiroyuki; Matsushita, Tadashi; Ito, Masahisa; Kuroda, Haruo.

1984-03-01

An EXAFS spectrometer installed on the beam line 10B at the Photon Factory is designed to cover the photon energy between 4 and 30 keV. Utilizing either a channel-cut or two flat silicon crystals as a monochromator, a beam intensity between 10 8 and 10 9 photons/sec is obtained at 9 keV with a resolution of 1 eV. The performance of the spectrometer, such as a signal-to-noise ratio or an energy resolution is demonstrated with examples of K edge absorption spectra of bromine, germanium, gallium arsenide, and zinc selenide. (author)

Magneto-transport studies on Bi2Te2+xSe1–x (x = 0.05 and 0.10 topological insulators

Directory of Open Access Journals (Sweden)

Bushra Irfan

2016-09-01

Full Text Available Bi2Te2Se is one of the most promising three dimensional topological insulators, for the study of surface states. In this work, we report the results of transport and magneto-transport behavior of Bi2Te2+xSe1–x (x=0.05 and 0.10 single crystals grown using modified Bridgeman technique. Resistance versus temperature measurements show semiconducting behavior for x = 0.05 and 0.10 crystals. Linear magnetoresistance is observed for Bi2Te2.05Se0.95 (i.e. x=0.05 whereas, Bi2Te2.10Se0.90 (x=0.10 single crystal shows a conductance fluctuations at low magnetic field.

Super-ionic conductivity in (1D) nanofibrous TlGaTe2

International Nuclear Information System (INIS)

Sardarly, R.M.; Samedov, O.A.; Abdullaev, A.P.; Salmanov, F.T.; Urbanovic, A.; Garet, F.; Coutaz, J.-L.

2010-01-01

Full text : Nanodimension topologic-disorder materials constitute an important feature in the development of modern electronics. Among such materials, TlGaTe 2 is a p-type semiconductor with a nanofibrous structure Ga 3 +Te 2 - 2 groups form chains extending along the c-axis of the material. These negatively charged chains are bonded together by Tl+ ions. The resulting tetragonal lattice is characterized by a 18 D4h group symmetry. Recently, much attention has been paid to systems that behave as if they had less than 3 spatial dimensions. Such materials are often called quasi-one-dimensional (1D) nanorods, nanofibrous or nanochains. It was already studied the temperature dependence of conductivity σ (T) and current-voltage (I-V) characteristics of TlGaTe 2 . In the ohmic region of the I -V curve, σ (T) exhibits a behavior typical of hopping conductivity, which can be modeled in the framework of the Mott approximation. Moreover, it was determined the values of the density of localized states, the activation energy, the hop lengths, and the difference between the energies of states and the concentration of deep traps. The abrupt variation of the I-V curve is ascribed to the Pool-Frenkel thermal-field effect, which allows to obtain the concentration of ionized centers, the free-path lengths, the Frenkel coefficients and the shape of the potential well of TlGaTe 2 . For T>300 K, TlGaTe 2 crystals present interesting nonlinear electrical behaviors, such as switching effects and a negative-differential-resistance (NDR) region in their S-type I-V characteristics. In the NDR region, self-excited oscillations of the voltage were also observed. Here, it was investigated the temperature dependence of TlGaTe 2 crystals conductivity σ (T) in two experimental geometries, i.e. parallel and perpendicularly to the tetragonal c-axis of the crystal. The observed sharp increase of TlGaTe 2 conductivity results from a strong change of the number of the high-mobility ions. The

Structural and optical features of InGaAs quantum dots grown on Si(001) substrates

CERN Document Server

Vdovin, V I; Rzaev, M M; Burbaev, T M

2002-01-01

A multilayer GaAs/SiGe/Si heterostructure with InGaAs quantum dots (QDs) embedded in a GaAs layer was grown by molecular beam epitaxy (MBE) on a Si(001) substrate. A step-graded Si sub 1 sub - sub x Ge sub x (0 <= x <= 1) buffer layer and a GaAs layer with In sub y Ga sub 1 sub sub - sub y As (y approx 0.5) QDs were deposited consecutively in two different MBE systems. The heterostructure exhibits intense photoluminescence in the region of 1.3 mu m at room temperature. Perfect crystal InGaAs islands with height less than 10 nm are the sources of this radiation.

A Precision Low-Energy Measurement of the Weak Mixing Angle in Moller Scattering

Energy Technology Data Exchange (ETDEWEB)

Mastromarino, P.

2005-01-26

The E-158 experiment at the Stanford Linear Accelerator Center (SLAC) measures the parity-violating cross-section asymmetry in electron-electron (Moeller) scattering at low Q{sup 2}. This asymmetry, whose Standard Model prediction is roughly -150 parts per billion (ppb), is directly proportional to (1-4 sin{sup 2} {theta}{sub W}), where {theta}{sub W} is the weak mixing angle. Measuring this asymmetry to within 10% provides an important test of the Standard Model at the quantum loop level and probes for new physics at the TeV scale. The experiment employs the SLAC 50 GeV electron beam, scattering it off a liquid hydrogen target. A system of magnets and collimators is used to isolate and focus the Moeller scattering events into an integrating calorimeter. The electron beam is generated at the source using a strained, gradient-doped GaAs photocathode, which produces roughly 5 x 10{sup 11} electrons/pulse (at a beam rate of 120 Hz) with {approx} 80% longitudinal polarization. The helicity of the beam can be rapidly switched, eliminating problems associated with slow drifts. Helicity-correlations in the beam parameters (charge, position, angle and energy) are minimized at the source and corrected for using precision beam monitoring devices.

Microscopic local bonding and optically-induced switching for Ge{sub 2}Sb{sub 2}Te{sub 5} alloys: A tale of four pseudo-binary and three binary tie-lines in Ge-Sb-Te phase field

Energy Technology Data Exchange (ETDEWEB)

Lucovsky, G.; Baker, D.A.; Washington, J.P.; Paesler, M.A. [Department of Physics, North Carolina State University, Raleigh, NC (United States)

2009-05-15

Ge{sub 2}Sb{sub 2}Te{sub 5} (GST-225) has emerged as an active medium for applications in reversible, ReWritable (RW) optical memory discs. Many studies have focused on the properties of this alloy, relative to the other GST compositions on tie-lines in the Ge-Sb-Te ternary phase field; (i) Sb{sub 2}Te to GeTe{sub 2}: (ii) Sb{sub 2}Te{sub 3}: to GeTe; (iii) GeSb to Te: and (iv) the truncated tie-line from GST-124 to Sb. This article focuses instead on the binary atomic join-lines, Te-Ge, Ge-Sb and Sb-Te, that comprise the perimeter of the Ge-Sb-Te ternary diagram. Three eutectic compositions, one on each perimeter segment: (i) Ge{sub 12}Sb{sub 88}; (ii) Te{sub 25}Sb{sub 75}; and (iii) Ge{sub 17}Te{sub 83} have been identified. Focussing on the significance of these eutectic compositions, and (i) building on previous publications from our group, and (ii) relying on two recently published articles, a new model for the RW properties of GST-22T has been proposed. Finally comparisons are made between GST and AIST RW films. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Investigation of beam self-polarization in the future e+e− circular collider

CERN Document Server

AUTHOR|(CDS)2075800

2016-10-24

The use of resonant depolarization has been suggested for precise beam energy measurements (better than 100 keV) in the eþe− Future Circular Collider (FCC-eþe−) for Z and WW physics at 45 and 80 GeV beam energy respectively. Longitudinal beam polarization would benefit the Z peak physics program; however it is not essential and therefore it will be not investigated here. In this paper the possibility of selfpolarized leptons is considered. Preliminary results of simulations in presence of quadrupole misalignments and beam position monitors (BPMs) errors for a simplified FCC-eþe− ring are presented.

E10 cosmology

International Nuclear Information System (INIS)

Kleinschmidt, Axel; Nicolai, Hermann

2006-01-01

We construct simple exact solutions to the E 10 /K(E 10 ) coset model by exploiting its integrability. Using the known correspondences with the bosonic sectors of maximal supergravity theories, these exact solutions translate into exact cosmological solutions. In this way, we are able to recover some recently discovered solutions of M-theory exhibiting phases of accelerated expansion, or, equivalently, S-brane solutions, and thereby accommodate such solutions within the E 10 /K(E 10 ) model. We also discuss the situation regarding solutions with non-vanishing (constant) curvature of the internal manifold

Collimation quench test with 6.5 TeV proton beams

CERN Document Server

Salvachua Ferrando, Belen Maria; Bruce, Roderik; Hermes, Pascal Dominik; Holzer, Eva Barbara; Jacquet, Delphine; Kalliokoski, Matti; Mereghetti, Alessio; Mirarchi, Daniele; Redaelli, Stefano; Skordis, Eleftherios; Valentino, Gianluca; Valloni, Alessandra; Wollmann, Daniel; Zerlauth, Markus; CERN. Geneva. ATS Department

2016-01-01

We show here the analysis of the MD test that aimed to quench the superconducting magnets in the dispersion suppressor region downstream of the main betatron collimation system. In Run I there were several attempts to quench the magnets in the same region. This was done by exciting the Beam 2 in a controlled way using the transverse damper and generating losses leaking from the collimation cleaning. No quench was achieved in 2013 with a maximum of 1 MW of beam power loss absorbed by the collimation system at 4 TeV beam energy. In 2015 a new collimation quench test was done at 6.5 TeV aiming at similar power loss over longer period, 5-10 s. The main outcome of this test is reviewed.

Multi-GeV electron-positron beam generation from laser-electron scattering.

Science.gov (United States)

Vranic, Marija; Klimo, Ondrej; Korn, Georg; Weber, Stefan

2018-03-16

The new generation of laser facilities is expected to deliver short (10 fs-100 fs) laser pulses with 10-100 PW of peak power. This opens an opportunity to study matter at extreme intensities in the laboratory and provides access to new physics. Here we propose to scatter GeV-class electron beams from laser-plasma accelerators with a multi-PW laser at normal incidence. In this configuration, one can both create and accelerate electron-positron pairs. The new particles are generated in the laser focus and gain relativistic momentum in the direction of laser propagation. Short focal length is an advantage, as it allows the particles to be ejected from the focal region with a net energy gain in vacuum. Electron-positron beams obtained in this setup have a low divergence, are quasi-neutral and spatially separated from the initial electron beam. The pairs attain multi-GeV energies which are not limited by the maximum energy of the initial electron beam. We present an analytical model for the expected energy cutoff, supported by 2D and 3D particle-in-cell simulations. The experimental implications, such as the sensitivity to temporal synchronisation and laser duration is assessed to provide guidance for the future experiments.

Development of a hybrid sputtering/evaporation process for Cu(In,Ga)Se{sub 2} thin film solar cells

Energy Technology Data Exchange (ETDEWEB)

Acciarri, M.; Binetti, S.; Le Donne, A.; Lorenzi, B.; Caccamo, L.; Miglio, L. [Dipartimento di Scienza dei Materiali e Solar Energy Research Center MIB-SOLAR, Universita di Milano Bicocca, Milan (Italy); Moneta, R.; Marchionna, S.; Meschia, M. [Voltasolar s.r.l, Turate (Italy)

2011-08-15

In this paper we report a new method for Cu(In,Ga)Se{sub 2} deposition for solar cell application. Differently from the common co-evaporation process, an alterative approach for thin film Cu(In,Ga)Se{sub 2} has been tested: the sputtering deposition of metal elements combined with the selenium evaporation. We have studied the relationships between the growth parameters of our hybrid sputtering/evaporation method and the chemical-physical properties of the CIGS films. The cells are completed with a CdS buffer layer deposited by chemical bath deposition and ZnO + ITO deposited by RF sputtering. Test solar cells of 0.5 cm{sup 2} have shown an efficiency of 10% and 2.5% on glass and stainless steel substrate respectively. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

A case for hidden b anti b tetraquarks based on e+e- → b anti b cross sections between √(s) = 10.54 and 11.20 GeV

International Nuclear Information System (INIS)

Ali, Ahmed; Hambrock, Christian; Ahmed, Ishtiaq; Aslam, M. Jamil

2009-11-01

We study the spectroscopy and dominant decays of the bottomonium-like tetraquarks (bound diquarks-antidiquarks), focusing on the lowest lying P-wave [bq][anti b anti q] states Y [bq] (with q=u,d), having J PC =1 -- . To search for them, we analyse the BABAR data obtained during an energy scan of the e + e - →b anti b cross section in the range of √(s)=10.54 to 11.20 GeV. We find that these data are consistent with the presence of an additional b anti b state Y [bq] with a mass of 10.90 GeV and a width of about 30 MeV apart from the Υ(5S) and Υ(6S) resonances. A closeup of the energy region around the Y [bq] -mass may resolve this state in terms of the two mass eigenstates, Y [b,l] and Y [b,h] , with a mass difference, estimated as about 6 MeV. We tentatively identify the state Y [bq] (10900) from the R b -scan with the state Y b (10890) observed by BELLE in the process e + e - →Y b (10890)→Υ(1S,2S)π + π - due to their proximity in masses and decay widths. (orig.)

Anomalous Phase Change in [(GeTe)2/(Sb2Te3)]20 Superlattice Observed by Coherent Phonon Spectroscopy

Science.gov (United States)

Makino, K.; Saito, Y.; Mitrofanov, K.; Tominaga, J.; Kolobov, A. V.; Nakano, T.; Fons, P.; Hase, M.

The temperature-dependent ultrafast coherent phonon dynamics of topological (GeTe)2/(Sb2Te3) super lattice phase change memory material was investigated. By comparing with Ge-Sb-Te alloy, a clear contrast suggesting the unique phase change behavior was found.

LHC Beam Dump System: Analysis of beam commissioning, performance and the consequences of abnormal operation

CERN Document Server

Kramer, Thomas

2011-01-01

The LHC accelerates proton beams to a momentum of up to 7 TeV/c. At this energy level and with nominal beam intensity the stored energy of 360 MJ per beam is sufficient to melt 500 kg of copper. In addition up to 10 GJ are stored within the LHC magnet system at top energy. It is obvious that such a machine needs well designed safety and protection systems. The LHC Beam Dump System (LBDS) is such a system and one of the most critical once concerning machine protection and safe operation. It is used to dispose of high intensity beams between 450 GeV and 7 TeV and is thus designed to fast extract beam in a loss free way and to transfer it to an external absorber. For each ring systems of 15 horizontal fast kicker magnets (MKD), 15 vertically deflecting magnetic septa (MSD) and 10 diluter kicker magnets (MKB) are installed. This thesis is concerned with the analysis of the LBDS performance under normal operating parameters as well as under abnormal conditions like in the event of asynchronous beam abort or missin...

Interdiffusion effect on GaAsSbN/GaAs quantum well structure studied by 10-band k·p model

International Nuclear Information System (INIS)

Dang, Y.X.; Fan, W.J.; Ng, S.T.; Wicaksono, S.; Yoon, S.F.; Zhang, D.H.

2007-01-01

The effect of annealing on the photoluminescence (PL) in GaAsSbN/GaAs quantum well (QW) grown by solid-source molecular-beam epitaxy (SS-MBE) has been investigated. Low-temperature (4 K) PL peaks shift to higher energy sides with the increase of annealing temperature. An As-Sb atomic interdiffusion at the heterointerface is proposed to model this effect. The compositional profile of the QW after interdiffusion is modeled by an error function distribution and calculated with the 10-band k·p method. When the diffusion length equals to 1.4 nm, a corresponding transition energy blueshift of 36 meV is derived. This agrees with the experimental result under the optimum condition (750 deg. C at 5 min)

/B(E2) values from low-energy Coulomb excitation at an ISOL facility: the /N=80,82 Te isotopes

Science.gov (United States)

Barton, C. J.; Caprio, M. A.; Shapira, D.; Zamfir, N. V.; Brenner, D. S.; Gill, R. L.; Lewis, T. A.; Cooper, J. R.; Casten, R. F.; Beausang, C. W.; Krücken, R.; Novak, J. R.

2003-01-01

B(E2;0+1→2+1) values for the unstable, neutron-rich nuclei 132,134Te were determined through Coulomb excitation, in inverse kinematics, of accelerated beams of these nuclei. The systematics of measured B(E2) values from the ground state to the first excited state have been extended to the N=82 shell closure in the Te nuclei and have been compared with the predictions of different theories. The measurements were performed at the Holifield Radioactive Ion Beam Facility (HRIBF) using the GRAFIK detector. The success of this approach, which couples a 5.7% efficient through-well NaI(Tl) γ-ray detector with thin foil microchannel plate beam detectors, also demonstrates the feasibility for Coulomb excitation studies of neutron-rich nuclei even further from the valley of beta stability, both at present-generation ISOL facilities and at the proposed Rare Isotope Accelerator.

Integral measurement of the {sup 12}C(n, p){sup 12}B reaction up to 10 GeV

Energy Technology Data Exchange (ETDEWEB)

Zugec, P.; Bosnar, D. [University of Zagreb, Department of Physics, Faculty of Science, Zagreb (Croatia); Colonna, N.; Barbagallo, M.; Mastromarco, M.; Tagliente, G.; Variale, V. [Istituto Nazionale di Fisica Nucleare, Bari (Italy); Ventura, A. [Istituto Nazionale di Fisica Nucleare, Bologna (Italy); Mengoni, A. [ENEA, Bologna (Italy); Altstadt, S.; Langer, C.; Lederer, C.; Reifarth, R.; Schmidt, S.; Weigand, M. [Johann-Wolfgang-Goethe Universitaet, Frankfurt (Germany); Andrzejewski, J.; Marganiec, J.; Perkowski, J. [Uniwersytet Lodzki, Lodz (Poland); Audouin, L.; Leong, L.S.; Tassan-Got, L. [Centre National de la Recherche Scientifique/IN2P3 - IPN, Orsay (France); Becares, V.; Cano-Ott, D.; Garcia, A.R.; Gonzalez-Romero, E.; Martinez, T.; Mendoza, E. [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain); Becvar, F.; Krticka, M.; Kroll, J.; Valenta, S. [Charles University, Prague (Czech Republic); Belloni, F.; Mondalaers, W.; Plompen, A.; Schillebeeckx, P. [European Commission JRC, Institute for Reference Materials and Measurements, Geel (Belgium); Berthoumieux, E.; Fraval, K.; Gunsing, F. [CEA/Saclay - IRFU, Gif-sur-Yvette (France); Billowes, J.; Ware, T.; Wright, T. [University of Manchester, Manchester (United Kingdom); Boccone, V.; Brugger, M.; Calviani, M.; Cerutti, F.; Chiaveri, E.; Chin, M.; Ferrari, A.; Guerrero, C.; Losito, R.; Roman, F.; Rubbia, C.; Tsinganis, A.; Versaci, R.; Vlachoudis, V.; Weiss, C. [CERN, Geneva (Switzerland); Calvino, F.; Cortes, G.; Gomez-Hornillos, M.B.; Riego, A. [Universitat Politecnica de Catalunya, Barcelona (Spain); Carrapico, C.; Goncalves, I.F.; Sarmento, R.; Vaz, P. [Universidade de Lisboa, C2TN-Instituto Superior Tecnico, Lisboa (Portugal); Cortes-Giraldo, M.A.; Praena, J.; Quesada, J. [Universidad de Sevilla, Sevilla (Spain); Cosentino, L.; Finocchiaro, P. [INFN - Laboratori Nazionali del Sud, Catania (Italy); Diakaki, M.; Karadimos, D.; Kokkoris, M.; Vlastou, R. [National Technical University of Athens (NTUA), Athens (Greece); Domingo-Pardo, C.; Giubrone, G.; Tain, J.L. [CSIC-Universidad de Valencia, Instituto de Fisica Corpuscular, Valencia (Spain); Dressler, R.; Heinitz, S.; Kivel, N.; Schumann, D. [Paul Scherrer Institut, Villigen (Switzerland); Duran, I.; Tarrio, D. [Universidade de Santiago de Compostela, Santiago de Compostela (Spain); Eleftheriadis, C.; Manousos, A. [Aristotle University of Thessaloniki, Thessaloniki (Greece); Ganesan, S.; Gurusamy, P.; Saxena, A. [Bhabha Atomic Research Centre (BARC), Mumbai (India); Griesmayer, E.; Jericha, E.; Leeb, H. [Atominstitut der Oesterreichischen Universitaeten, Technische Universitaet Wien, Wien (Austria); Jenkins, D.G.; Vermeulen, M.J. [University of York, York, Heslington (United Kingdom); Kaeppeler, F. [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, Karlsruhe (Germany); Lo Meo, S. [Istituto Nazionale di Fisica Nucleare, Bologna (Italy); ENEA, Bologna (Italy); Massimi, C.; Mingrone, F.; Vannini, G. [Dipartimento di Fisica, Universita di Bologna (IT); INFN, Bologna (IT); Mastinu, P. [Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Legnaro (IT); Milazzo, P.M. [Istituto Nazionale di Fisica Nucleare, Trieste (IT); Mirea, M. [Horia Hulubei National Institute of Physics and Nuclear Engineering - IFIN HH, Magurele (RO); Musumarra, A. [Universita di Catania, Dipartimento di Fisica e Astronomia DFA, Catania (IT); INFN-Laboratori Nazionali del Sud, Catania (IT); Paradela, C. [European Commission JRC, Institute for Reference Materials and Measurements, Geel (BE); Universidade de Santiago de Compostela, Santiago de Compostela (ES); Pavlik, A. [Faculty of Physics, University of Vienna, Wien (AT); Rauscher, T. [University of Hertfordshire, Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, Hatfield (GB); University of Basel, Department of Physics, Basel (CH); Wallner, A. [Faculty of Physics, University of Vienna, Wien (AT); Australian National University, Research School of Physics and Engineering, Canberra (AU)

2016-04-15

The integral measurement of the {sup 12}C(n, p){sup 12}B reaction was performed at the neutron time-of-flight facility nTOF at CERN. The total number of {sup 12}B nuclei produced per neutron pulse of the nTOF beam was determined using the activation technique in combination with a time-of-flight technique. The cross section is integrated over the nTOF neutron energy spectrum from reaction threshold at 13.6 MeV to 10 GeV. Having been measured up to 1GeV on basis of the {sup 235}U(n, f) reaction, the neutron energy spectrum above 200 MeV has been re-evaluated due to the recent extension of the cross section reference for this particular reaction, which is otherwise considered a standard up to 200 MeV. The results from the dedicated GEANT4 simulations have been used to evaluate the neutron flux from 1 GeV up to 10 GeV. The experimental results related to the {sup 12}C(n, p){sup 12}B reaction are compared with the evaluated cross sections from major libraries and with the predictions of different GEANT4 models, which mostly underestimate the {sup 12}B production. On the contrary, a good reproduction of the integral cross section derived from measurements is obtained with TALYS-1.6 calculations, with optimized parameters. (orig.)

Investigations on the local structures and the spin Hamiltonian parameters for Cu{sup 2+} in (90-x)TeO{sub 2}-10GeO{sub 2}-xWO{sub 3} glasses

Energy Technology Data Exchange (ETDEWEB)

Feng, Chun-Rong [Xihua Univ., Chengdu (China). School of Science; Jian, Jun [Xihua Univ., Chengdu (China). Dept. of Applied Physics; Chen, Xiao-Hong; Du, Quan; Wang, Ling [Xihua Univ., Chengdu (China). School of Science and Research Center for Advanced Computation

2018-04-01

The local structures and the spin Hamiltonian parameters (SHPs) for Cu{sup 2+} in (90-x)TeO{sub 2}-10GeO{sub 2}-xWO{sub 3} glasses are theoretically investigated at various WO{sub 3} concentrations (x=7.5, 15, 22.5 and 30 mol%). Subject to the Jahn-Teller effect, the [CuO{sub 6}]{sup 10-} groups are found to experience the small or moderate tetragonal elongation distortions (characterised by the relative tetragonal elongation ratios ρ ∼ 0.35-3.09%) in C{sub 4} axis. With only three adjusted coefficients a, b and ω, the relevant model parameters (Dq, k and ρ) are described by the Fourier type and linear functions, respectively, and the measured concentration dependences of the d-d transition bands and SHPs are reproduced. The maximum of g {sub parallel} and the minimum of vertical stroke A {sub parallel} vertical stroke at x=15 mol% are illustrated from the abrupt decrease of the copper-oxygen electron cloud admixtures or covalency and the obvious decline of the copper 3d-3s (4s) orbital admixtures due to the decreasing electron cloud density around oxygen ligands spontaneously bonding with Cu{sup 2+} and Te{sup 4+} (W{sup 6+}), respectively.

Stimulated emission in heterostructures with double InGaAs/GaAsSb/GaAs quantum wells, grown on GaAs and Ge/Si(001) substrates

Energy Technology Data Exchange (ETDEWEB)

Yablonsky, A. N., E-mail: yablonsk@ipm.sci-nnov.ru; Morozov, S. V.; Gaponova, D. M.; Aleshkin, V. Ya. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Shengurov, V. G.; Zvonkov, B. N.; Vikhrova, O. V.; Baidus’, N. V. [Lobachevsky State University of Nizhny Novgorod (Russian Federation); Krasil’nik, Z. F. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

2016-11-15

We report the observation of stimulated emission in heterostructures with double InGaAs/GaAsSb/GaAs quantum wells, grown on Si(001) substrates with the application of a relaxed Ge buffer layer. Stimulated emission is observed at 77 K under pulsed optical pumping at a wavelength of 1.11 μm, i.e., in the transparency range of bulk silicon. In similar InGaAs/GaAsSb/GaAs structures grown on GaAs substrates, room-temperature stimulated emission is observed at 1.17 μm. The results obtained are promising for integration of the structures into silicon-based optoelectronics.

Experimental Constraints on γ-Ray Pulsar Gap Models and the Pulsar GeV to Pulsar Wind Nebula TeV Connection

Science.gov (United States)

Abeysekara, A. U.; Linnemann, J. T.

2015-05-01

The pulsar emission mechanism in the gamma ray energy band is poorly understood. Currently, there are several models under discussion in the pulsar community. These models can be constrained by studying the collective properties of a sample of pulsars, which became possible with the large sample of gamma ray pulsars discovered by the Fermi Large Area Telescope. In this paper we develop a new experimental multi-wavelength technique to determine the beaming factor ≤ft( {{f}{Ω }} \\right) dependance on spin-down luminosity of a set of GeV pulsars. This technique requires three input parameters: pulsar spin-down luminosity, pulsar phase-averaged GeV flux, and TeV or X-ray flux from the associated pulsar wind nebula (PWN). The analysis presented in this paper uses the PWN TeV flux measurements to study the correlation between {{f}{Ω }} and \\dot{E}. The measured correlation has some features that favor the Outer Gap model over the Polar Cap, Slot Gap, and One Pole Caustic models for pulsar emission in the energy range of 0.1-100 GeV, but one must keep in mind that these simulated models failed to explain many of the most important pulsar population characteristics. A tight correlation between the pulsar GeV emission and PWN TeV emission was also observed, which suggests the possibility of a linear relationship between the two emission mechanisms. In this paper we also discuss a possible mechanism to explain this correlation.

Reflectance-anisotropy study of the dynamics of molecular beam epitaxy growth of GaAs and InGaAs on GaAs(001)

Energy Technology Data Exchange (ETDEWEB)

Ortega-Gallegos, J.; Lastras-Martinez, A.; Lastras-Martinez, L.F. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi. Alvaro Obregon 64, San Luis Potosi (Mexico); Balderas-Navarro, R.E. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi. Alvaro Obregon 64, San Luis Potosi (Mexico); Facultad de Ciencias, Universidad Autonoma de San Luis Potosi. Alvaro Obregon 64, San Luis Potosi (Mexico)

2008-07-01

Reflectance-Anisotropy (RA) observations during the Molecular Beam Epitaxy (MBE) growth of zincblende semiconductors films were carried out using the E{sub 1} optical transition as a probe. We follow the kinetics of the deposition of GaAs and In{sub 0.3}Ga{sub 0.7}As on GaAs(001) at growth rates of 0.2 and 0.25 ML/s, respectively. During growth we used a constant As{sub 4} or As{sub 2} flux pressure of 5 x 10{sup -6} Torr. Clear RA-oscillations were observed during growth with a period that nearly coincides with the growth period for a Ga-As bilayer. RHEED was used as an auxiliary technique in order to obtain a correlation between RHEED and RA oscillations. On the basis of our results, we argue that RAS oscillations are mainly associated to periodic changes in surface atomic structure. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Reflectance-anisotropy study of the dynamics of molecular beam epitaxy growth of GaAs and InGaAs on GaAs(001)

International Nuclear Information System (INIS)

Ortega-Gallegos, J.; Lastras-Martinez, A.; Lastras-Martinez, L.F.; Balderas-Navarro, R.E.

2008-01-01

Reflectance-Anisotropy (RA) observations during the Molecular Beam Epitaxy (MBE) growth of zincblende semiconductors films were carried out using the E 1 optical transition as a probe. We follow the kinetics of the deposition of GaAs and In 0.3 Ga 0.7 As on GaAs(001) at growth rates of 0.2 and 0.25 ML/s, respectively. During growth we used a constant As 4 or As 2 flux pressure of 5 x 10 -6 Torr. Clear RA-oscillations were observed during growth with a period that nearly coincides with the growth period for a Ga-As bilayer. RHEED was used as an auxiliary technique in order to obtain a correlation between RHEED and RA oscillations. On the basis of our results, we argue that RAS oscillations are mainly associated to periodic changes in surface atomic structure. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

77 FR 38714 - Proposed Collection; Comment Request for the TE/GE Compliance Check Questionnaires

Science.gov (United States)

2012-06-28

... TE/GE Compliance Check Questionnaires AGENCY: Internal Revenue Service (IRS), Treasury. ACTION..., the IRS is soliciting comments concerning the TE/GE Compliance Check Questionnaires. DATES: Written... [email protected] . SUPPLEMENTARY INFORMATION: Title: TE/GE Compliance Check Questionnaires. OMB...

Thermally-induced crystallization behaviour of 80GeSe{sub 2}–20Ga{sub 2}Se{sub 3} glass as probed by combined X-ray diffraction and PAL spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Shpotyuk, O., E-mail: shpotyuk@novas.lviv.ua [Scientific Research Company “Carat”, 202, Stryjska str., Lviv 79031 (Ukraine); Institute of Physics of Jan Dlugosz University, 13/15, al. Armii Krajowej, Czestochowa 42201 (Poland); Calvez, L.; Petracovschi, E. [Equipe Verres et Céramiques, UMR-CNRS 6226, Institute des Sciences chimiques de Rennes, Université de Rennes 1, 35042 Rennes Cedex (France); Klym, H. [Lviv polytechnic National University, 12 Bandera str., Lviv 79013 (Ukraine); Ingram, A. [Physics Faculty of Opole University of Technology, 75, Ozimska str., Opole 45370 (Poland); Demchenko, P. [Ivan Franko National University of Lviv, 6, Kyryla and Mefodiya Str., Lviv 79005 (Ukraine)

2014-01-05

Highlights: • Chalcogenide Ge–Ga–Se glasses were annealed at 380 °C for 10, 25 and 50 h. • Crystallization of glasses during annealing indicates formation of crystals. • Structural changes are described by two-state positron trapping model. • Modification leading to nucleation and fragmentation of free volume of glasses. • The Ge–Ga–Se systems cannot be classified as typical pseudo-binary system. -- Abstract: Crystallization behaviour of 80GeSe{sub 2}–20Ga{sub 2}Se{sub 3} glass caused by thermal annealing at 380 °C for 10, 25 and 50 h are studied using X-ray diffraction and positron annihilation lifetime spectroscopy. It is shown that the structural changes caused by crystallization can be adequately described by positron trapping modes determined within two-state model. The observed changes in defect-related component in the fit of experimental positron lifetime spectra for annealed glasses testifies in a favour of structural fragmentation of larger free volume entities into smaller ones with preceding nucleation in the initial stage of thermal annealing. Because of strong deviation in defect-free bulk positron lifetime from corresponding additive values proper to boundary constituents, the studied glasses cannot be considered as typical representatives of pseudo-binary cut-section.

Efeito de ácido giberélico, GA3, e GA4 + GA7 em pós-colheita de crisântemo e solidago.

Directory of Open Access Journals (Sweden)

Denise Laschii

1999-05-01

Full Text Available O experimento foi instalado no laboratório do Departamento de Horticultura da FCA/ UNESP, no período de 14 de novembro a 3 de dezembro de 1998. As hastes de crisântemo (Dendranthema grandiflora Tzvelev e solidago (Solidago canadensis L. foram selecionadas e colocadas em solução de "pulsing", por 24 horas, visando avaliar as respostas aos seguintes tratamentos: Água (testemunha, GA3 10 mg.L-1 (Pro-Gibb; GA3 20 mg.L-I; GA3 30 mg.L-I; GA4 + GA7 10 mg.L-1 (Pro-Vibe, GA4 + GA7 20 mg.L-1 e GA4 + GA7 30 mg.L-1. Após os tratamentos de "pulsing", as hastes foram colocadas em recipientes contendo 1.000 mL de água, que foi trocada a cada dois dias. Avaliou-se o número de dias até o descarte, tanto para hastes de solidago quanto para crisântemo, para cada tratamento testado. Avaliou--se também a qualidade das folhas de solidago conforme o seguinte critério: índice de qualidade (IQ = 3 (folhas verdes, IQ = 2 (folhas em início de amarelecimento e IQ = 1 (folhas amarelas ou queimadas. Pelos resultados concluiu-se que: hastes cortadas de solidago e crisântemo diferiram quanto às respostas aos tratamentos pós-colheita, em relação ao tipo de giberelina utilizada; GA4 + GA7 10 mg.L-1 foi eficiente na manutenção da qualidade de hastes cortadas de solidago, e GA3 nas concentrações utilizadas no experimento apresentaram efeito deletério nas folhas de solidago; GA3 10 e 20 mg.L-1 foram mais eficientes na manutenção da qualidade pós-colheita de hastes de crisântemo.

Unexpected Ge-Ge contacts in the two-dimensional Ge{sub 4}Se{sub 3}Te phase and analysis of their chemical cause with the density of energy (DOE) function

Energy Technology Data Exchange (ETDEWEB)

Kuepers, Michael; Konze, Philipp M.; Maintz, Stefan; Steinberg, Simon [Institute of Inorganic Chemistry, Chair of Solid-State and Quantum Chemistry, RWTH Aachen University (Germany); Mio, Antonio M.; Cojocaru-Miredin, Oana; Zhu, Min; Wuttig, Matthias [I. Physikalisches Institut, RWTH Aachen University (Germany); Mueller, Merlin; Mayer, Joachim [Gemeinschaftslabor fuer Elektronenmikroskopie, RWTH Aachen University (Germany); Luysberg, Martina [Ernst-Ruska-Center, Forschungszentrum Juelich GmbH (Germany); Dronskowski, Richard [Institute of Inorganic Chemistry, Chair of Solid-State and Quantum Chemistry, RWTH Aachen University (Germany); Juelich-Aachen Research Alliance (JARA-HPC), RWTH Aachen University (Germany)

2017-08-14

A hexagonal phase in the ternary Ge-Se-Te system with an approximate composition of GeSe{sub 0.75}Te{sub 0.25} 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 Ge{sub 4}Se{sub 3}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 Ge{sub 4}Se{sub 3}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. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Substrate Misorientation Effects On (A1,Ga)As And (Al,Ga)As/GaAs Structures Grown By Molecular Beam Epitaxy

Science.gov (United States)

Tsui, Raymond K.; Kramer, Gary D.; Curless, J. A.; Peffley, Marilyn S.

1987-04-01

(Al,Ga)As layers have rough surface morphologies when deposited under certain growth conditions in molecular beam epitaxy (MBE). This leads to poor interfaces between (A1,Ga)- As and GaAs and degraded performance in heterojunction devices. We have observed that by misorienting the substrate slightly from (100), in a manner specific to the growth conditions, smooth (Al,Ga)As layers 3-4 μm thick can be grown at a rate of ≍ 1 μm/h for various AlAs mole fractions, x. Similar conditions for nominal (100) result in a rough, textured morphology. Experiments were carried out using flat substrates of specific misorientations as well as lens-shaped substrates. The lenticular substrates allowed all orientations within 14° of (100) [i.e., out to (511)] to be evaluated in one growth run. Deposition conditions that were varied included x, substrate temperature, and V/III beam flux ratio. Smooth layers obtained using optimal misorientations showed superior optical characteris-tics as determined from low-temperature photoluminescence (PL) measurements. The 4.2K PL spectra of smooth layers exhibit well-resolved exciton-related peaks, and do not have the deeper-level defect-related peaks observed in the spectra of rough layers. Single quantum well structures with A10.3Ga0.7As barriers and a 100 A-wide GaAs well deposited on mis-oriented substrates also have superior optical properties compared to a structure grown on nominal (100). Such findings may have significant implications for the performance of heterojunction device structures grown by MBE.

78 FR 63565 - Proposed Collection; Comment Request for the TE/GE Compliance Check Questionnaires

Science.gov (United States)

2013-10-24

... TE/GE Compliance Check Questionnaires AGENCY: Internal Revenue Service (IRS), Treasury. ACTION..., the IRS is soliciting comments concerning the TE/GE Compliance Check Questionnaires. DATES: Written... . SUPPLEMENTARY INFORMATION: Title: TE/GE Compliance Check Questionnaires. OMB Number: 1545-2071. Form Number: Not...

X-ray micro-beam characterization of a small pixel spectroscopic CdTe detector

Science.gov (United States)

Veale, M. C.; Bell, S. J.; Seller, P.; Wilson, M. D.; Kachkanov, V.

2012-07-01

A small pixel, spectroscopic, CdTe detector has been developed at the Rutherford Appleton Laboratory (RAL) for X-ray imaging applications. The detector consists of 80 × 80 pixels on a 250 μm pitch with 50 μm inter-pixel spacing. Measurements with an 241Am γ-source demonstrated that 96% of all pixels have a FWHM of better than 1 keV while the majority of the remaining pixels have FWHM of less than 4 keV. Using the Diamond Light Source synchrotron, a 10 μm collimated beam of monochromatic 20 keV X-rays has been used to map the spatial variation in the detector response and the effects of charge sharing corrections on detector efficiency and resolution. The mapping measurements revealed the presence of inclusions in the detector and quantified their effect on the spectroscopic resolution of pixels.

As-grown deep-level defects in n-GaN grown by metal-organic chemical vapor deposition on freestanding GaN

International Nuclear Information System (INIS)

Chen Shang; Ishikawa, Kenji; Hori, Masaru; Honda, Unhi; Shibata, Tatsunari; Matsumura, Toshiya; Tokuda, Yutaka; Ueda, Hiroyuki; Uesugi, Tsutomu; Kachi, Tetsu

2012-01-01

Traps of energy levels E c -0.26 and E c -0.61 eV have been identified as as-grown traps in n-GaN grown by metal-organic chemical vapor deposition by using deep level transient spectroscopy of the Schottky contacts fabricated by resistive evaporation. The additional traps of E c -0.13 and E c -0.65 eV have been observed in samples whose contacts are deposited by electron-beam evaporation. An increase in concentration of the E c -0.13 and E c -0.65 eV traps when approaching the interface between the contact and the GaN film supports our argument that these traps are induced by electron-beam irradiation. Conversely, the depth profiles of as-grown traps show different profiles between several samples with increased or uniform distribution in the near surface below 50 nm. Similar profiles are observed in GaN grown on a sapphire substrate. We conclude that the growth process causes these large concentrations of as-grown traps in the near-surface region. It is speculated that the finishing step in the growth process should be an essential issue in the investigation of the surface state of GaN.

Theoretical and experimental investigations of the properties of Ge2Sb2Te5 and indium-doped Ge2Sb2Te5 phase change material

Science.gov (United States)

Singh, Gurinder; Kaura, Aman; Mukul, Monika; Singh, Janpreet; Tripathi, S. K.

2014-06-01

We have carried out comprehensive computational and experimental study on the face-centered cubic Ge2Sb2Te5 (GST) and indium (In)-doped GST phase change materials. Structural calculations, total density of states and crystal orbital Hamilton population have been calculated using first-principle calculation. 5 at.% doping of In weakens the Ge-Te, Sb-Te and Te-Te bond lengths. In element substitutes Sb to form In-Te-like structure in the GST system. In-Te has a weaker bond strength compared with the Sb-Te bond. However, both GST and doped alloy remain in rock salt structure. It is more favorable to replace Sb with In than with any other atomic position. X-ray diffraction (XRD) analysis has been carried out on thin film of In-doped GST phase change materials. XRD graph reveals that In-doped phase change materials have rock salt structure with the formation of In2Te3 crystallites in the material. Temperature dependence of impedance spectra has been calculated for thin films of GST and doped material. Thickness of the as-deposited films is calculated from Swanepoel method. Absorption coefficient (α) has been calculated for amorphous and crystalline thin films of the alloys. The optical gap (indirect band gap) energy of the amorphous and crystalline thin films has also been calculated by the equation α hν = β (hν - E_{{g }} )2 . Optical contrast (C) of pure and doped phase change materials have also been calculated. Sufficient optical contrast has been found for pure and doped phase change materials.

Theoretical and experimental investigations of the properties of Ge2Sb2Te5 and indium-doped Ge2Sb2Te5 phase change material

International Nuclear Information System (INIS)

Singh, Gurinder; Kaura, Aman; Mukul, Monika; Singh, Janpreet; Tripathi, S.K.

2014-01-01

We have carried out comprehensive computational and experimental study on the face-centered cubic Ge 2 Sb 2 Te 5 (GST) and indium (In)-doped GST phase change materials. Structural calculations, total density of states and crystal orbital Hamilton population have been calculated using first-principle calculation. 5 at.% doping of In weakens the Ge-Te, Sb-Te and Te-Te bond lengths. In element substitutes Sb to form In-Te-like structure in the GST system. In-Te has a weaker bond strength compared with the Sb-Te bond. However, both GST and doped alloy remain in rock salt structure. It is more favorable to replace Sb with In than with any other atomic position. X-ray diffraction (XRD) analysis has been carried out on thin film of In-doped GST phase change materials. XRD graph reveals that In-doped phase change materials have rock salt structure with the formation of In 2 Te 3 crystallites in the material. Temperature dependence of impedance spectra has been calculated for thin films of GST and doped material. Thickness of the as-deposited films is calculated from Swanepoel method. Absorption coefficient (α) has been calculated for amorphous and crystalline thin films of the alloys. The optical gap (indirect band gap) energy of the amorphous and crystalline thin films has also been calculated by the equation αhν = β(hν - E g ) 2 . Optical contrast (C) of pure and doped phase change materials have also been calculated. Sufficient optical contrast has been found for pure and doped phase change materials. (orig.)

Investigation of the total charm-pair cross section in nonresonant e+e- annihilations at √s = 10.5 GeV

International Nuclear Information System (INIS)

Bowcock, T.; Kinoshita, K.; Pipkin, F.M.

1988-01-01

We report results from two new methods for measuring the total production of charmed particles in nonresonant e + e - annihilations at √s = 10.5 GeV. The rate for detection of events containing two reconstructed charmed mesons relative to that for events containing one is used to extract information about total charm production independent of decay branching fractions. The value of ΔR/sub c//sub c-bar/, the total charm-pair cross section normalized to the pointlike μ-pair cross section, is found to be 1.13/sub -0.13//sup +0.17/ +- 0.09, under an assumption of limited particle correlations. In an independent analysis the inclusive cross section for e + e - →qq-bar→e/sup +- /X is measured to be 0.293 +- 0.017 +- 0.017 nb. Using measured relative production rates and semileptonic branching fractions of D 0 and D + mesons and estimates of these quantities for D/sub s/ and Λ/sub c/, this is found to correspond to ΔR/sub c//sub c-bar/ = 2.07 +- 0.12 +- 0.26. These two measurements are discussed in the context of measurements made by reconstruction of exclusive hadronic decay modes and of theoretical expectations

Low operation voltage of GaN-based LEDs with Al-doped ZnO upper contact directly on p-type GaN without insert layer

Science.gov (United States)

Chen, P. H.; Chen, Yu An; Chang, L. C.; Lai, W. C.; Kuo, Cheng Huang

2015-07-01

Al-doped ZnO (AZO) film was evaporated on double-side polished sapphire, p-GaN layers, n+-InGaN-GaN short-period superlattice (SPS) structures, and GaN-based light-emitting diodes (LEDs) by e-beam. The AZO film on the p-GaN layer after thermal annealing exhibited an extremely high transparency (98% at 450 nm) and a small specific contact resistance of 2.19 × 10-2 Ω cm2, which was almost the same as that of as-deposited AZO on n+-SPS structure. With 20 mA injection current, the forward voltages were 3.30 and 3.27 V, whereas the output powers were 4.32 and 4.07 mW for the LED with AZO on insert n+-SPS upper contact and the LED with AZO on p-GaN upper contact (without insert layer), respectively. The small specific contact resistance and low operation voltage of LED with AZO on p-GaN upper contact was achieved by rapid thermal annealing (RTA) process.

Influence of boat material on the structure, stoichiometry and optical properties of gallium sulphide films prepared by thermal evaporation

International Nuclear Information System (INIS)

Rao, Pritty; Kumar, Sanjiv; Sahoo, N.K.

2015-01-01

The paper describes the deposition of thin films of gallium sulphide on soda-lime glass substrates by thermal evaporation of chemically synthesized powders consisting of gallium sulphide and gallium oxyhydroxide from a Mo or Ta boat and the evolution of their compositional, structural and optical properties on vacuum annealing. The films deposited from Mo or Ta boats possessed distinctly different properties. The Mo-boat evaporated pristine films were amorphous, transparent (α ∼ 10 3  cm −1 ) in visible region and had a direct band gap of about 3.2 eV. Vacuum annealing at 723 K brought about their crystallization predominantly into cubic γ-Ga 2 S 3 and a blue shift by about 0.2 eV. The Ta-boat evaporated pristine films were also amorphous but were absorbing (α ∼ 10 4  cm −1 ) and had a direct band gap of about 2.1 eV. These crystallized into hexagonal GaS and experienced a blue shift by more than 1.0 eV on vacuum annealing at 723 K. The dissimilar properties of the two kinds of films arose mainly from their different atomic compositions. The Mo-boat evaporated pristine films contained Ga and S in ∼1:1 atomic proportions while those prepared using Ta-boat were Ga rich which impaired their transmission characteristics. The former composition favoured the stabilization of S rich gallium sulphide (Ga 2 S 3 ) phase while the latter stabilised S deficient species, GaS. Besides inducing crystallization, vacuum annealing at 723 K also caused the diffusion of Ga in excess of atomic composition of the phase formed, into soda-lime glass which improved the optical transmission of the films. Gallium oxyhydroxide, an inevitable co-product of the chemical synthetic process, in the evaporant introduced oxygen and hydrogen impurities in the films which do not seem to significantly influence their optical properties. - Highlights: • Gallium sulphide films are prepared by thermal evaporation from a Mo or Ta boat. • Mo-boat prepared pristine film has Ga

The cosmic ray primary composition between $10^{15}$ and $10^{16}$ ev from Extensive Air Showers electromagnetic and TeV muon data

CERN Document Server

Aglietta, M; Ambrosio, M; Antolini, R; Antonioli, P; Arneodo, F; Baldini, A; Barbarino, G C; Barish, B C; Battistoni, G; Becherini, Y; Bellotti, R; Bemporad, C; Bergamasco, L; Bernardini, P; Bertaina, M; Bilokon, H; Bower, C; Brigida, M; Bussino, S; Cafagna, F; Calicchio, M; Campana, D; Carboni, M; Caruso, R; Castagnoli, C; Castellina, A; Cecchini, S; Cei, F; Chiarella, V; Chiavassa, A; Choudhary, B C; Cini, G; Coutu, S; Cozzi, M; D'Ettorre-Piazzoli, B; De Cataldo, G; De Marzo, C; De Mitri, I; De Vincenzi, M; Dekhissi, H; Derkaoui, J; Di Credico, A; Di Sciascio, G; Erriquez, O; Favuzzi, C; Forti, C; Fulgione, W; Fusco, P; Galeotti, P; Ghia, P L; Giacomelli, G; Giannini, G; Giglietto, N; Giorgini, M; Grassi, M; Grillo, A; Guarino, F; Gustavino, C; Habig, A; Hanson, K; Heinz, R; Iacovacci, M; Iarocci, E; Katsavounidis, E; Katsavounidis, I; Kearns, E; Kim, H; Kyriazopoulou, S; Lamanna, E; Lane, C; Levin, D S; Lipari, P; Longley, N P; Longo, M J; Loparco, F; Maaroufi, F; Mancarella, G; Mandrioli, G; Mannocchi, G; Margiotta, A; Marini, A; Martello, D; Marzari-Chiesa, A; Mazziotta, M N; Michael, D G; Monacelli, P; Montaruli, T; Monteno, M; Morello, C; Mufson, S; Musser, J; Navarra, G; Nicolò, D; Nolty, R; Orth, C; Osteria, G; Palamara, O; Patera, V; Patrizii, L; Pazzi, R; Peck, C W; Perrone, L; Petrera, S; Popa, V; Rainó, A; Reynoldson, J; Ronga, F; Saavedra, O; Satriano, C; Scapparone, E; Scholberg, K; Sciubba, A; Serra, P; Sioli, M; Sirri, G; Sitta, M; Spinelli, P; Spinetti, M; Spurio, M; Stamerra, A; Steinberg, R; Stone, J L; Sulak, L R; Surdo, A; Tarle, G; Togo, V; Trinchero, G C; Vakili, M; Valchierotti, S; Vallania, P; Vernetto, S; Vigorito, C; Walter, C W; Webb, R; 10.1016/j.astropartphys.2003.10.004

2004-01-01

The cosmic ray primary composition in the energy range between 10/sup 15/ and 10/sup 16/ eV, i.e., around the "knee" of the primary spectrum, has been studied through the combined measurements of the EAS-TOP air shower array (2005 m a.s.l., 10/sup 5/ m/sup 2/ collecting area) and the MACRO underground detector (963 m a.s.l., 3100 m w.e. of minimum rock overburden, 920 m/sup 2/ effective area) at the National Gran Sasso Laboratories. The used observables are the air shower size (N/sub e/) measured by EAS-TOP and the muon number (N /sub mu /) recorded by MACRO, The two detectors are separated on average by 1200 m of rock, and located at a respective zenith angle of about 30 degrees . The energy threshold at the surface for muons reaching the MACRO depth is approximately 1.3 TeV. Such muons are produced in the early stages of the shower development and in a kinematic region quite different from the one relevant for the usual N/sub mu /-N/sub e/ studies. The measurement leads to a primary composition becoming hea...

Description of the ternary system Cu-Ge-Te

International Nuclear Information System (INIS)

Dogguy, M.; Carcaly, C.; Rivet, J.; Flahaut, J.

1977-01-01

The Cu-Ge-Te ternary system has been studied by DTA and by crystallographic and metallographic analysis. The existence of a ternary compound Cu 2 GeTe 3 is demonstrated; this compound has a ternary incongruent melting point at 500 0 C. This ternary compound has a superstructure of a zinc blende type. The study shows the existence of five ternary eutectics. Two liquid-liquid miscibility gaps exist: the first is situated entirely in the ternary system; the second gives a monotectic region within the ternary system. (Auth.)

Improving the thermoelectric performance of metastable rock-salt GeTe-rich Ge-Sb-Te thin films through tuning of grain orientation and vacancies

Energy Technology Data Exchange (ETDEWEB)

Chen, I. Nan [Department of Physics, National Taiwan University, Taipei (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei (China); Chong, Cheong-Wei [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei (China); Center for Condensed Matter Sciences, National Taiwan University, Taipei (China); Wong, Deniz P.; Lyu, Liang-Ming; Chien, Wei-Lun; Anbalagan, Ramakrishnan; Aminzare, Masoud; Chen, Kuei-Hsien [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei (China); Chen, Yang-Fang [Department of Physics, National Taiwan University, Taipei (China); Chen, Li-Chyong [Center for Condensed Matter Sciences, National Taiwan University, Taipei (China)

2016-12-15

Phase-change memory materials such as the pseudobinary GeTe-Sb{sub 2}Te{sub 3} compounds have recently gained attention for their good thermoelectric properties, which can be used for power-generation/cooling applications. In this work, GeTe-rich Ge-Sb-Te thin films deposited using a radio-frequency magnetron sputtering method readily exhibit the metastable face-centered cubic (FCC) phase at room temperature. This is in stark contrast to its bulk form, which only transforms to its FCC phase after a transition temperature of around 350 C. Based on previous works, the FCC phase contributes to the superior thermoelectric properties of this material system. In this study, by decreasing the working deposition pressure, the preferred orientation of (200) plane is observed that translates to improved carrier mobility. Moreover, increasing the annealing temperature has been shown to decrease the carrier concentration due to Te deficiency, leading to a significant improvement in the Seebeck coefficient of the film. By combining these effects, an optimized thermoelectric power factor (21 μW/cm K{sup 2}) was obtained at an operating temperature of 350 C. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Growth and characterization of highly tensile strained Ge{sub 1−x}Sn{sub x} formed on relaxed In{sub y}Ga{sub 1−y}P buffer layers

Energy Technology Data Exchange (ETDEWEB)

Wang, Wei; D' Costa, Vijay Richard; Dong, Yuan; Liang, Gengchiau; Yeo, Yee-Chia, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Loke, Wan Khai; Yoon, Soon Fatt [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Yin, Tingting; Shen, Zexiang [School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Zhang, Zheng; Pan, Jisheng [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, #08-03, Singapore 138634 (Singapore); Tok, Eng Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

2016-03-28

Ge{sub 0.94}Sn{sub 0.06} films with high tensile strain were grown on strain-relaxed In{sub y}Ga{sub 1−y}P virtual substrates using solid-source molecular beam epitaxy. The in-plane tensile strain in the Ge{sub 0.94}Sn{sub 0.06} film was varied by changing the In mole fraction in In{sub x}Ga{sub 1−x}P buffer layer. The tensile strained Ge{sub 0.94}Sn{sub 0.06} films were investigated by transmission electron microscopy, x-ray diffraction, and Raman spectroscopy. An in-plane tensile strain of up to 1% in the Ge{sub 0.94}Sn{sub 0.06} was measured, which is much higher than that achieved using other buffer systems. Controlled thermal anneal experiment demonstrated that the strain was not relaxed for temperatures up to 500 °C. The band alignment of the tensile strained Ge{sub 0.94}Sn{sub 0.06} on In{sub 0.77}Ga{sub 0.23}P was obtained by high resolution x-ray photoelectron spectroscopy. The Ge{sub 0.94}Sn{sub 0.06}/In{sub 0.77}Ga{sub 0.23}P interface was found to be of the type I band alignment, with a valence band offset of 0.31 ± 0.12 eV and a conduction band offset of 0.74 ± 0.12 eV.

Microstructure evolution in pulsed laser deposited epitaxial Ge-Sb-Te chalcogenide thin films

Energy Technology Data Exchange (ETDEWEB)

Ross, Ulrich; Lotnyk, Andriy, E-mail: andriy.lotnyk@iom-leipzig.de; Thelander, Erik; Rauschenbach, Bernd

2016-08-15

The thin film deposition and structure of highly oriented telluride compounds is of particular interest for phase-change applications in next-generation non-volatile memory such as heterostructure designs, as well as for the investigation of novel optical, thermoelectric and ferroelectric properties in layered telluride compounds. In this work, epitaxial Ge-Sb-Te thin films were successfully produced by pulsed laser deposition on silicon with and without amorphous SiO{sub x} interlayer at elevated process temperatures from a Ge{sub 2}Sb{sub 2}Te{sub 5} target. Aberration-corrected high-resolution scanning transmission electron microscopy (STEM) imaging reveals a distinct interface configuration of the trigonal phase connected by a quasi van der Waals gap (vacancy) to the Sb/Te-passivated single crystalline Si substrate, yet also an intermediate textured growth regime in which the substrate symmetry is only weakly coupled to the thin film orientation, as well as strong deviation of composition at high deposition temperatures. Textured growth of Ge-Sb-Te thin film was also observed on SiO{sub x}/Si substrate with no evidence of an intermediate Sb/Te surface layer on top of an SiO{sub x} layer. In addition, particular defect structures formed by local reorganization of the stacking sequence across the vacancy gap are observed and appear to be intrinsic to these van der Waals-layered compounds. Theoretical image simulations of preferred stacking sequences can be matched to individual building blocks in the Ge-Sb-Te grain. - Highlights: • Atomic-resolution Cs-corrected STEM imaging of PLD deposited Ge-Sb-Te thin films. • Changing of overall composition with increasing deposition temperature. • Direct imaging of surface passivation Sb/Te layer at the Ge-Sb-Te/Si(111) interface. • The Sb/Te passivation layer is not a prerequisite for highly oriented growth of Ge-Sb-Te thin films.

n-type dopants in (001) β-Ga2O3 grown on (001) β-Ga2O3 substrates by plasma-assisted molecular beam epitaxy

Science.gov (United States)

Han, Sang-Heon; Mauze, Akhil; Ahmadi, Elaheh; Mates, Tom; Oshima, Yuichi; Speck, James S.

2018-04-01

Ge and Sn as n-type dopants in (001) β-Ga2O3 films were investigated using plasma-assisted molecular beam epitaxy. The Ge concentration showed a strong dependence on the growth temperature, whereas the Sn concentration remains independent of the growth temperature. The maximum growth temperature at which a wide range of Ge concentrations (from 1017 to 1020 cm-3) could be achieved was 675 °C while the same range of Sn concentration could be achieved at growth temperature of 750 °C. Atomic force microscopy results revealed that higher growth temperature shows better surface morphology. Therefore, our study reveals a tradeoff between higher Ge doping concentration and high quality surface morphology on (001) β-Ga2O3 films grown by plasma-assisted molecular beam epitaxy. The Ge doped films had an electron mobility of 26.3 cm2 V-1 s-1 at the electron concentration of 6.7 × 1017 cm-3 whereas the Sn doped films had an electron mobility of 25.3 cm2 V-1 s-1 at the electron concentration of 1.1 × 1018 cm-3.

Synthesis and optical properties of (GaAs)yGe5-2y alloys assembled from molecular building blocks

Science.gov (United States)

Sims, P. E.; Wallace, P. M.; Xu, Chi; Poweleit, C. D.; Claflin, B.; Kouvetakis, J.; Menéndez, J.

2017-09-01

Monocrystalline alloys of GaAs and Ge with compositions (GaAs)yGe5-2y have been synthesized following a chemical vapor deposition approach that promotes the incorporation of Ga and As atoms as isolated donor-acceptor pairs. The structural and optical properties show distinct behavior relative to (GaAs)1-xGe2x counterparts produced by conventional routes. Strong band gap photoluminescence is observed in the 0.5-0.6 eV range for samples whose compositions approach the GaAsGe3 limit for isolated Ga-As pairs. In such samples, the Ge-like Raman modes appear at higher frequencies and are considerably narrower than those observed in samples with higher Ge concentrations. These results suggest that the growth mechanism may favor the formation of ordered phases comprising Ga-As-Ge3 tetrahedra. In contrast with the diamond-to-zincblende ordering transition previously reported for III-V-IV alloys, ordered structures built from Ga-As-Ge3 tetrahedra feature III-III and V-V pairs as third-nearest neighbors, and therefore both the III- and V-components are equally present in each of two fcc sublattices of the average diamond-like structure. These bonding arrangements likely lead to the observed optical response, indicating potential applications of these materials in mid-IR technologies integrated on Si.

Radiation-free superhydrophilic and antifogging properties of e-beam evaporated TiO2 films on glass

Science.gov (United States)

Garlisi, Corrado; Palmisano, Giovanni

2017-10-01

In this work, we show the unique wettability properties of TiO2 thin films deposited by e-beam evaporation on glass and treated at 500 °C. The deposited materials exhibited compact non-porous structures and their non-UV activated superwetting behavior was characterized, emphasizing the better performance compared to the bare glass substrate and to a commercial self-cleaning glass (Pilkington Activ™) even in terms of antifogging and optical properties. The results demonstrate how the superhydrophilic character arises from the used deposition technique inducing a large amount of oxygen vacancies further boosted by the annealing treatment, allowing for the fabrication of a pioneering material in the area of multifunctional coatings. The superhydrophilic character was maintained even at an extremely small thickness (20 nm), similarly to the adhesion of the film to the glass substrate, as confirmed by ultrasound stress tests and the cross-cut test performed according to ISO 2409 standard. The photocatalytic activity of the e-beam evaporated film was also assessed by degradation of methanol, 2-propanol and toluene under UV light in a gas phase reactor and the performance was found to be in most cases superior compared to Pilkington Activ™.

Experimental charge density determination in iso-structural Tellurides: Hf0.85GeTe4 and ZrGeTe4

International Nuclear Information System (INIS)

Israel, S.; Saravana Kumar, S.; Sheeba, R.A.J.R.; Saravanan, R.

2012-01-01

Hf 0.85 GeTe 4 is isostructural with stoichiometric ZrGeTe 4 and their crystal structure adopts a two-dimensional layered structure, each layer being composed of two unique one-dimensional chains of face sharing Hf/Zr-centered bicapped trigonal prisms and corner sharing Ge- centered tetrahedra. These layers stack on top of each other to complete the three-dimensional structure with undulating van der Waals gaps. Single crystal XRD is used for the refinement of the structural parameters. The space group Cmc2 1 was considered and the structure was the refined using the harmonic model by the software called JANA2006. The refined structure factors were then subsequently used in MEM (Maximum Entropy Method) technique for the construction of the charge density in the unit cell using software called PRIMA and then visualized with the help of visualization software called VESTA

1 to 2 GeV/c beam line for hypernuclear and kaon research

International Nuclear Information System (INIS)

Chrien, R.E.

1985-01-01

A kaon beam line operating in the range from 1.0 to 2.0 GeV/c is proposed. The line is meant for kaon and pion research in a region hitherto inaccessible to experimenters. Topics in hypernuclear and kaon physics of high current interest include the investigation of doubly strange nuclear systems with the K - ,K + reaction, searching for dibaryon resonances, hyperon-nucleon interactions, hypernuclear γ rays, and associated production of excited hypernuclei. The beam line would provide separated beams of momentum analyzed kaons at intensities greater than 10 6 particles per spill with a momentum determined to one part in a thousand. This intensity is an order of magnitude greater than that currently available. 63 references

Study of the structure and chemical bonding of crystalline Ge_4Sb_2Te_7 using first principle calculations

International Nuclear Information System (INIS)

Singh, Janpreet; Singh, Satvinder; Tripathi, S. K.; Singh, Gurinder; Kaura, Aman

2016-01-01

The atomic arrangements and chemical bonding of stable Ge_4Sb_2Te_7 (GeTe rich), a phase-change material, have been investigated by means of ab initio total energy calculations. To study the atomic arrangement, GeTe block is considered into -TeSbTeSbTe- block and -Te-Te- layer in the stacking I and II respectively. The stacking I is energetically more stable than the stacking II. The reason for more stability of the stacking I has been explained. The chemical bonding has been studied with the electronic charge density distribution around the atomic bonds. The quantity of electronic charge loosed or gained by atoms has been calculated using the Bader charge analysis. The metallic character has been studied using band structures calculations. The band gap for the stacking I and II is 0.463 and 0.219 eV respectively.

High-electron-mobility GaN grown on free-standing GaN templates by ammonia-based molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Kyle, Erin C. H., E-mail: erinkyle@umail.ucsb.edu; Kaun, Stephen W.; Burke, Peter G.; Wu, Feng; Speck, James S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Wu, Yuh-Renn [Institute of Photonics and Optoelectronics, and Department of Electrical Engineering, National Taiwan University, Taipei City 10617, Taiwan (China)

2014-05-21

The dependence of electron mobility on growth conditions and threading dislocation density (TDD) was studied for n{sup −}-GaN layers grown by ammonia-based molecular beam epitaxy. Electron mobility was found to strongly depend on TDD, growth temperature, and Si-doping concentration. Temperature-dependent Hall data were fit to established transport and charge-balance equations. Dislocation scattering was analyzed over a wide range of TDDs (∼2 × 10{sup 6} cm{sup −2} to ∼2 × 10{sup 10} cm{sup −2}) on GaN films grown under similar conditions. A correlation between TDD and fitted acceptor states was observed, corresponding to an acceptor state for almost every c lattice translation along each threading dislocation. Optimized GaN growth on free-standing GaN templates with a low TDD (∼2 × 10{sup 6} cm{sup −2}) resulted in electron mobilities of 1265 cm{sup 2}/Vs at 296 K and 3327 cm{sup 2}/Vs at 113 K.

Volume-change-free GeTeN films for high-performance phase-change memory

International Nuclear Information System (INIS)

Yin, You; Hosaka, Sumio; Zhang, Hui; Liu, Yang; Yu, Qi

2013-01-01

N-doping into GeTe is investigated with the aim of reducing the volume change upon crystallization, which usually induces a huge internal stress in phase-change memory devices. It is demonstrated that the thickness change upon crystallization of a N-doped GeTe (GeTeN) film is almost zero when N is doped in an appropriate amount. Cracks resulting from the stress caused by volume change disappear and the mean crystal size decreases by more than 50% upon N-doping into GeTe. It is thought that the volume-change-free behaviour is due to the formation of low-density nitride and grain refinement. (paper)

Characteristics of InAs/InGaAs/GaAs QDs on GeOI substrates with single-peak 1.3 µm room-temperature emission

International Nuclear Information System (INIS)

Liang, Y Y; Yoon, S F; Loke, W K; Ngo, C Y; Fitzgerald, E A

2012-01-01

GaAs-based quantum dot (QD) systems, especially InAs/InGaAs/GaAs QDs, have demonstrated superior device performances as compared with higher dimensional systems. However, to realize high-speed optical interconnects for Si-based electronics, one will need to grow the QDs on Si substrates. While it is promising to integrate the InAs/InGaAs/GaAs QDs on Si with the use of germanium-on-insulator-on-silicon (GeOI) substrates, reported results exhibit bimodal QD sizes and double emission peaks, i.e. unsatisfactory for realistic applications. In this paper, we showed that with an optimized GaAs buffer, single-peak 1.33 µm room-temperature emission can be obtained from InAs/InGaAs/GaAs QDs on GeOI substrates. (paper)

Control of Laser Plasma Based Accelerators up to 1 GeV

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Kei [Univ. of Tokyo (Japan); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2007-12-01

This dissertation documents the development of a broadband electron spectrometer (ESM) for GeV class Laser Wakefield Accelerators (LWFA), the production of high quality GeV electron beams (e-beams) for the first time in a LWFA by using a capillary discharge guide (CDG), and a statistical analysis of CDG-LWFAs. An ESM specialized for CDG-LWFAs with an unprecedented wide momentum acceptance, from 0.01 to 1.1 GeV in a single shot, has been developed. Simultaneous measurement of e-beam spectra and output laser properties as well as a large angular acceptance (> ± 10 mrad) were realized by employing a slitless scheme. A scintillating screen (LANEX Fast back, LANEX-FB)--camera system allowed faster than 1 Hz operation and evaluation of the spatial properties of e-beams. The design provided sufficient resolution for the whole range of the ESM (below 5% for beams with 2 mrad divergence). The calibration between light yield from LANEX-FB and total charge, and a study on the electron energy dependence (0.071 to 1.23 GeV) of LANEX-FB were performed at the Advanced light source (ALS), Lawrence Berkeley National Laboratory (LBNL). Using this calibration data, the developed ESM provided a charge measurement as well. The production of high quality electron beams up to 1 GeV from a centimeter-scale accelerator was demonstrated. The experiment used a 310 μm diameter gas-filled capillary discharge waveguide that channeled relativistically-intense laser pulses (42 TW, 4.5 x 10¹⁸ W/cm²) over 3.3 centimeters of sufficiently low density (≃ 4.3 x 10¹⁸/cm³) plasma. Also demonstrated was stable self-injection and acceleration at a beam energy of ≃ 0.5 GeV by using a 225 μm diameter capillary. Relativistically-intense laser pulses (12 TW, 1.3 x 10¹⁸W/cm²) were guided over 3.3 centimeters of low density (≃ 3.5 x 10¹⁸/cm³) plasma in this experiment. A statistical analysis of the CDG

Studies for Muon Colliders at Center-of-Mass Energies of 10 TeV and 100 TeV

International Nuclear Information System (INIS)

King, Bruce J.

1999-01-01

Parameter lists are presented for speculative muon colliders at center-of-mass energies of 10 TeV and 100 TeV. The technological advances required to achieve the given parameters are itemized and discussed, and a discussion is given of the design goals and constraints. An important constraint for multi-TeV muon colliders is the need to minimize neutrino radiation from the collider ring

Ion-beam doping of GaAs with low-energy (100 eV) C + using combined ion-beam and molecular-beam epitaxy

Science.gov (United States)

Iida, Tsutomu; Makita, Yunosuke; Kimura, Shinji; Winter, Stefan; Yamada, Akimasa; Fons, Paul; Uekusa, Shin-ichiro

1995-01-01

A combined ion-beam and molecular-beam-epitaxy (CIBMBE) system has been developed. This system consists of an ion implanter capable of producing ions in the energy range of 30 eV-30 keV and conventional solid-source MBE. As a successful application of CIBMBE, low-energy (100 eV) carbon ion (C+) irradiation during MBE growth of GaAs was carried out at substrate temperatures Tg between 500 and 590 °C. C+-doped layers were characterized by low-temperature (2 K) photoluminescence (PL), Raman scattering, and van der Pauw measurements. PL spectra of undoped GaAs grown by CIBMBE revealed that unintentional impurity incorporation into the epilayer is extremely small and precise doping effects are observable. CAs acceptor-related emissions such as ``g,'' [g-g], and [g-g]β are observed and their spectra are significantly changed with increasing C+ beam current density Ic. PL measurements showed that C atoms were efficiently incorporated during MBE growth by CIBMBE and were optically well activated as an acceptor in the as-grown condition even for Tg as low as 500 °C. Raman measurement showed negligible lattice damage of the epilayer bombarded with 100 eV C+ with no subsequent heat treatment. These results indicate that contamination- and damage-free impurity doping without postgrowth annealing can be achieved by the CIBMBE method.

Ion-beam doping of GaAs with low-energy (100 eV) C(+) using combined ion-beam and molecular-beam epitaxy

Science.gov (United States)

Lida, Tsutomu; Makita, Yunosuke; Kimura, Shinji; Winter, Stefan; Yamada, Akimasa; Fons, Paul; Uekusa, Shin-Ichiro

1995-01-01

A combined ion-beam and molecular-beam-epitaxy (CIBMBE) system has been developed. This system consists of an ion implanter capable of producing ions in the energy range of 30 eV - 30 keV and conventional solid-source MBE. As a successful application of CIBMBE, low-energy (100 eV) carbon ion (C(+)) irradiation during MBE growth of GaAs was carried out at substrate temperatures T(sub g) between 500 and 590 C. C(+)-doped layers were characterized by low-temperature (2 K) photoluminescence (PL), Raman scattering, and van der Pauw measurements. PL spectra of undoped GaAs grown by CIBMBE revealed that unintentional impurity incorporation into the epilayer is extremely small and precise doping effects are observable. C(sub As) acceptor-related emissions such as 'g', (g-g), and (g-g)(sub beta) are observed and their spectra are significantly changed with increasing C(+) beam current density I(sub c). PL measurements showed that C atoms were efficiently incorporated during MBE growth by CIBMBE and were optically well activated as an acceptor in the as-grown condition even for T(sub g) as low as 500 C. Raman measurement showed negligible lattice damage of the epilayer bombarded with 100 eV C(+) with no subsequent heat treatment. These results indicate that contamination- and damage-free impurity doping without postgrowth annealing can be achieved by the CIBMBE method.

Design and construction of a mode converter from TE10(rectangular) to TE11(circular)

International Nuclear Information System (INIS)

Tubbing, B.J.D.

1984-08-01

The design and manufacturing of a wavelength mode converter from the TE 10 (rectangular) mode in oversized rectangular to the TE 11 (circular) mode in oversized circular waveguide is described. A differential equation for the cross-sectional shape of the converter was solved numerically. A stainless-steel mandrel was produced on a numerically controlled milling machine. Sixteen converters were produced by means of electroforming on one mandrel. (Auth.)

Heavily doped GaAs:Te layers grown by MOVPE using diisopropyl telluride as a source

Energy Technology Data Exchange (ETDEWEB)

Daniltsev, V. M.; Demidov, E. V.; Drozdov, M. N.; Drozdov, Yu. N., E-mail: drozdyu@ipmras.ru; Kraev, S. A.; Surovegina, E. A.; Shashkin, V. I.; Yunin, P. A. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

2016-11-15

The capabilities of GaAs epitaxial layers extremely heavily doped with tellurium by metal-organic vapor-phase epitaxy using diisopropyl telluride as a source are studied. It is shown that tellurium incorporation into GaAs occurs to an atomic concentration of 10{sup 21} cm{sup –3} without appreciable diffusion and segregation effects. Good carrier concentrations (2 × 10{sup 19} cm{sup –3}) and specific contact resistances of non-alloyed ohmic contacts (1.7 × 10{sup –6} Ω cm{sup 2}) give grounds to use such layers to create non-alloyed ohmic contacts in electronic devices. A sharp decrease in the electrical activity of Te atoms, a decrease in the electron mobility, and an increase in the contact resistance at atomic concentrations above 2 × 10{sup 20} cm{sup –3} are detected.

Atomic scale insight into the amorphous structure of Cu doped GeTe phase-change material

International Nuclear Information System (INIS)

Zhang, Linchuan; Sa, Baisheng; Zhou, Jian; Sun, Zhimei; Song, Zhitang

2014-01-01

GeTe shows promising application as a recording material for phase-change nonvolatile memory due to its fast crystallization speed and extraordinary amorphous stability. To further improve the performance of GeTe, various transition metals, such as copper, have been doped in GeTe in recent works. However, the effect of the doped transition metals on the stability of amorphous GeTe is not known. Here, we shed light on this problem for the system of Cu doped GeTe by means of ab initio molecular dynamics calculations. Our results show that the doped Cu atoms tend to agglomerate in amorphous GeTe. Further, base on analyzing the pair correlation functions, coordination numbers and bond angle distributions, remarkable changes in the local structure of amorphous GeTe induced by Cu are obviously seen. The present work may provide some clues for understanding the effect of early transition metals on the local structure of amorphous phase-change compounds, and hence should be helpful for optimizing the structure and performance of phase-change materials by doping transition metals.

High power pulse electron beam modification and ion implantation of Hg{sub 1-x}Cd{sub x}Te crystals

Energy Technology Data Exchange (ETDEWEB)

Vojtsekhovskij, A V; Remnev, G E [Tomsk Polytechnic Univ. (Russian Federation). Nuclear Physics Inst.; Opekunov, M S; Kokhanenko, A P; Korotaev, A G; Denisov, Yu A; Oucherenko, D A [Tomsk State Univ. (Russian Federation). Dept. of Radiophysics

1997-12-31

Hg{sub 1-x}Cd{sub x}Te (MCT) samples (x = 0.21 - 0.22) were irradiated by pulse electron beams at doses of 10{sup 13} to 10{sup 17} cm{sup -2}. The electron beams possessed the following parameters: 500 keV electron energy (30-40 A/cm{sup 2} electron current density, 60-80 ns current pulse); 200 keV electron energy (8- 10 A/cm{sup 2} electron current density, 100-200 ns current pulse). The electric conductivity and recombination of modified samples were investigated by the Hall effect and photoconductivity methods. For the 200 keV electron energy beam irradiation, the n-type surface regions were obtained under threshold mechanisms of donor defect generation. For the 500 keV electron energy beam irradiation, the maximum value of charge carrier lifetimes occur in the p- to n-type conductivity conversion range for the initial p-type crystals due to the conductivity compensation. MCT samples (x = 0.21 - 0.22) were implanted with Al ions at doses of 10{sup 12}-10{sup 16} cm{sup -2}. The ion beams possessed the following parameters: (1-10) A/cm{sup 2} ion current density, (100-200) ns current pulse; (150-450) keV Al ion (Al{sup +},Al{sup ++}, Al{sup +++}). The ion distribution and doping profiles were investigated by PIGE and Hall effect methods. Comparison between MCT samples after power pulse ion implantation and after standard ion implantation demonstrates differences in ion distribution, doping profiles and defect formation radiation mechanisms. (author). 3 figs., 8 refs.

Al2O3 e-Beam Evaporated onto Silicon (100)/SiO2, by XPS

Energy Technology Data Exchange (ETDEWEB)

Madaan, Nitesh; Kanyal, Supriya S.; Jensen, David S.; Vail, Michael A.; Dadson, Andrew; Engelhard, Mark H.; Samha, Hussein; Linford, Matthew R.

2013-09-25

We report the XPS characterization of a thin film of Al2O3 (35 nm) deposited via e-beam evaporation onto silicon (100). The film was characterized with monochromatic Al Ka radiation. An XPS survey scan, an Al 2p narrow scan, and the valence band spectrum were collected. The Al2O3 thin film is used as a diffusion barrier layer for templated carbon nanotube (CNT) growth in the preparation of microfabricated thin layer chromatography plates.

Measurement of the ratio σB(W→eν)/σB(Z0→e+e-) in bar pp collisions at √s =1.8 TeV

International Nuclear Information System (INIS)

Abe, F.; Albrow, M.; Amidei, D.; Anway-Wiese, C.; Apollinari, G.; Areti, H.; Auchincloss, P.; Azfar, F.; Azzi, P.; Bacchetta, N.; Badgett, W.; Bailey, M.W.; Bao, J.; de Barbaro, P.; Barbaro-Galtieri, A.; Barnes, V.E.; Barnett, B.A.; Bartalini, P.; Bauer, G.; Baumann, T.; Bedeschi, F.; Behrends, S.; Belforte, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Benlloch, J.; Benton, D.; Beretvas, A.; Berge, J.P.; Bertolucci, S.; Bhatti, A.; Biery, K.; Binkley, M.; Bird, F.; Bisello, D.; Blair, R.E.; Blocker, C.; Bodek, A.; Bolognesi, V.; Bortoletto, D.; Boswell, C.; Boulos, T.; Brandenburg, G.; Buckley-Geer, E.; Budd, H.S.; Burkett, K.; Busetto, G.; Byon-Wagner, A.; Bryum, K.L.; Campagnari, C.; Campbell, M.; Caner, A.; Carithers, W.; Carlsmith, D.; Castro, A.; Cen, Y.; Cervelli, F.; Chapman, J.; Chiarelli, G.; Chikamatsu, T.; Cihangir, S.; Clark, A.G.; Cobal, M.; Contreras, M.; Conway, J.; Cooper, J.; Cordelli, M.; Coupal, D.P.; Crane, D.; Cunningham, J.D.; Daniels, T.; DeJongh, F.; Delchamps, S.; Dell'Agnello, S.; Dell'Orso, M.; Demortier, L.; Denby, B.; Deninno, M.; Derwent, P.F.; Devlin, T.; Dickson, M.; Donati, S.; Drucker, R.B.; Dunn, A.; Einsweiler, K.; Elias, J.E.; Ely, R.; Engels, E. Jr.; Eno, S.; Errede, D.; Errede, S.; Etchegoyen, A.; Fan, Q.; Farhat, B.; Fiori, I.; Flaugher, B.; Foster, G.W.; Franklin, M.; Frautschi, M.; Freeman, J.; Friedman, J.; Frisch, H.; Fry, A.; Fuess, T.A.; Fukui, Y.; Funaki, S.; Gagliardi, G.; Gallinaro, M.; Garfinkel, A.F.; Geer, S.; Gerdes, D.W.; Giannetti, P.; Giokaris, N.; Giromini, P.; Gladney, L.; Glenzinski, D.; Gold, M.; Gonzalez, J.; Gordon, A.; Goshaw, A.T.; Goulianos, K.; Grassmann, H.; Grewal, A.; Grieco, G.; Groer, L.; Grosso-Pilcher, C.; Haber, C.; Hahn, S.R.; Hamilton, R.; Handler, R.; Hans, R.M.; Hara, K.; Harral, B.; Harris, R.M.; Hauger, S.A.; Hauser, J.; Hawk, C.; Heinrich, J.; Hennessy, D.; Hollebeek, R.; Holloway, L.; Hoelscher, A.; Hong, S.; Houk, G.; Hu, P.; Huffman, B.T.; Hughes, R.; Hurst, P.

1994-01-01

We present a measurement of the ratio σB(W→ev)/σB(Z 0 →e + e - ) in bar pp collisions at √s =1.8 TeV. The data represent an integrated luminosity of 21.7 pb -1 from the 1992--1993 run of the Collider Detector at Fermilab. We find σB(W→eV)/σB(Z 0 →e + e - )=10.90±0.32(stat)±0.29(sys t). From this value, we extract a value for the W width, Γ(W)=2.064±0.061(stat)±0.059(syst) GeV, and the branching ratio, Γ(W→eV)/Γ(W)=0.1094±0.0033(stat)±0.0031(syst), and we set a decay-mode-independent limit on the top quark mass m top >62 GeV/c 2 at the 95% C.L

Heteroepitaxial Growth of Vacuum-Evaporated Si-Ge Films on Nano structured Silicon Substrates

International Nuclear Information System (INIS)

Ayu Wazira Azhari; Ayu Wazira Azhari; Kamaruzzaman Sopian; Saleem Hussain Zaidi

2015-01-01

In this study, a low-cost vacuum-evaporated technique is used in the heteroepitaxial growth of Si-Ge films. Three different surface variations are employed: for example polished Si, Si micro pyramids and Si nano pillars profiles. A simple metal-assisted chemical etching method is used to fabricate the Si nano pillars, with Ag acting as a catalyst. Following deposition, substrates are subjected to post-deposition thermal annealing at 1000 degree Celsius to improve the crystallinity of the Ge layer. Optical and morphological studies of surface area are conducted using field emission scanning electron microscopy (FE-SEM), Energy Dispersive X-ray (EDX), Raman spectroscopy and infrared spectroscopy. From the infrared spectroscopy analysis, the energy bandgap for Si-Ge films is estimated to be around 0.94 eV. This high-quality Si-Ge film is most favourable for optics, optoelectronics and high-efficiency solar cell applications. (author)

GeV partons and TeV hexons from a topological viewpoint

International Nuclear Information System (INIS)

Chew, G.F.; Issler, D.; Nicolescu, B.; Poenaru, V.

1984-04-01

An elementary TeV topological hadron supermultiplet breaks into GeV-scale mesons, baryons and baryoniums and TeV-scale hexons (extremely-heavy bosons corresponding to six topological constituents). Phenomena on the GeV scale are describable by parton graphs which give meaning to constituent quarks of QCD type. Hexons are responsible - through mixing - for electroweak-boson masses, may be responsible for cosmic-ray Centauro events, and promise novel TeV accelerator phenomena. 25 references

GeV partons and TeV hexons from a topological viewpoint

International Nuclear Information System (INIS)

Chew, G.F.; Issler, D.; Nicolescu, B.; Poenaru, V.

1984-04-01

An elementary TeV topological hadron supermultiplet breaks into GeV-scale mesons, baryons and baryoniums and TeV-scale ''hexons'' (extremely-heavy bosons corresponding to six topological constituents). Phenomena on the GeV scale are described by parton graphs which give meaning to constituent quarks of QCD type. Hexons are responsible -through mixing- for electroweak-bosons masses, may be responsible for cosmic-ray Centauro events, and promise novel TeV accelerator phenomena

Construction of an ''intelligent'' trigger system for kaons and study of the K+ production in the system Ne+NaF at 1.0 GeV/u

International Nuclear Information System (INIS)

Ahner, W.

1993-07-01

The technical part of this thesis describes the construction, the properties, and the experience from the application of an intelligent software trigger for the experiments on the production of positive kaons at the kaon spectrometer. The software trigger was applied in several beam-times. An essiential improvement in the yield of the registrated kaons was reached. The realization ensued by the application of standard components and represents a flexible and cost-efficient solution. The physical part of this thesis deals with the measurement of the double-differential cross section for positive kaons, positive pions, and protons in the system Ne+NaF at 1.0 GeV/u beam energy in the laboratory-angle range ofΘ lab =44 ±4 . the beam energy of 1.0 GeV/u lies below the threshold energy for the production of positive kaons in the collision of two free nucleons of E beam threshold =1.58 GeV. The momentum spectra of kaons and pions in the laboratory-momentum range from 270 MeV/c to 1140 MeV/c can be well described by a Boltzmann distribution in the c. m. system. The steepness parameter of the Boltzmann distributions amount to 64 MeV for kaons and 58 MeV for pions. The momentum-integrates cross section were determined from the extrapolation of the fitted Boltzmann distributions to: (dσ/dΩ lab ) ΔΩ lab K + =58.6±9.2 μb/sr and (dσ/dΩ lab ) ΔΩ lab π + =169±17 mb/sr. The total cross sections were calculated under the assumption of the isotropy in the c. m. system from the fitted distributions: σ 0 K + =335±52 μb and σ 0 π + =939±96 mb. The mass dependence of the meson production cross sections in the symmetrc collisional system Ne+NaF was studied and compared with the results of the study of the heavy collisional system Au+Au

e+e- collisions at 500 GeV: The physics potential

International Nuclear Information System (INIS)

Zerwas, P.M.

1992-08-01

In this report the physics potential of e + e - colliders in the first phase up to a c.m. energy of √s=500 GeV is assessed. A luminosity of L=10 33 cm -2 sec -1 has been assumed in general, leading to an integrated luminosity of about ∫L=10 fb -1 per year. See hints under the relevant topics. (orig./HSI)

Force10 networks performance in world's first transcontinental 10 gigabit ethernet network verified by Ixia

CERN Multimedia

2003-01-01

Force10 Networks, Inc., today announced that the performance of the Force10 E-Series switch/routers deployed in a transcontinental network has been verified as line-rate 10 GE throughput by Ixia, a leading provider of high-speed, network performance and conformance analysis systems. The network, the world's first transcontinental 10 GE wide area network, consists of a SURFnet OC-192 lambda between Geneva and the StarLight facility in Chicago via Amsterdam and another OC-192 lambda between this same facility in Chicago and Carleton University in Ottawa, Canada provided by CANARIE and ORANO (1/2 page).

Production of a 68Ge/68Ga generator

International Nuclear Information System (INIS)

Behrouz Shirazi; Behrouz Fateh; Mohammad Mirzaii; Gholamreza Aslani

2004-01-01

Background: Gallium-68 is a radioisotope with a half life of 68 min. As it has a specific decay mode, it is a positron emitter and hence, it is popularly used in nuclear medicine. The only way to obtain these nuclides is to produced the mother nuclease which is Germanium - 68. There are many nuclear reactions from which the Germanium - 68 is obtained, however, the best reaction is 69Ga (p,2n)68Ge. Materials and Methods: The cross section of this nuclear reaction was calculated with the ALICE-91 Code and the result was compared with the practical work done by other researchers. The comparing result was an acceptable one. Having the cross sections in mind, the best proton energy was calculated to be between 20-25 MeV Further research showed that Ga2O3 is the best type of target material. Therefore, it was necessary to design and make a suitable target holder for these k/nd of compositions, which for the very first time in Iran was done at Atomic Energy Organization of Iran (AEOI). The thickness of the target, bearing in mind the rate of energy loss in side the target material, was calculated with the SRIM Code and the Ga2O3 tablets were made with FT-IR instruments at Nuclear Research Center for Agriculture and Medicine (NRCAM). They were then bombarded with the 20, 21 and 22.5 MeV proton energy and the beam currents of 1.4, 7.5 and 13.3 μA.Two weeks after the bombardment the radio chemical separation of Germanium - 68 was done with concentrated acid HNO3 and applying heat. Then, the acid solution was evaporated till dried, after that, an EDTA solution (0.005 M, pH = 11) was added to recover the Germanium - 68. By passing the EDTA solution through the A12O3 column, Germanium - 68 radioisotope was adsorbed.Then another solution of EDTA (0.005 M, PH=11) was passed thorough the loaded column, almost all the natural Gallium impurities were removed.In this project the behavior of natural Gallium was studied via adding Gallium-67 as a tracer which it's half life is about

The effect of Se/Te ratio on transient absorption behavior and nonlinear absorption properties of CuIn0.7Ga0.3(Se1-xTex)2 (0 ≤ x ≤ 1) amorphous semiconductor thin films

Science.gov (United States)

Karatay, Ahmet; Küçüköz, Betül; Çankaya, Güven; Ates, Aytunc; Elmali, Ayhan

2017-11-01

The characterization of the CuInSe2 (CIS), CuInGaSe (CIGS) and CuGaSe2 (CGS) based semiconductor thin films are very important role for solar cell and various nonlinear optical applications. In this paper, the amorphous CuIn0.7Ga0.3(Se1-xTex)2 semiconductor thin films (0 ≤ x ≤ 1) were prepared with 60 nm thicknesses by using vacuum evaporation technique. The nonlinear absorption properties and ultrafast transient characteristics were investigated by using open aperture Z-scan and ultrafast pump-probe techniques. The energy bandgap values were calculated by using linear absorption spectra. The bandgap values are found to be varying from 0.67 eV to 1.25 eV for CuIn0.7Ga0.3Te2, CuIn0.7Ga0.3Se1.6Te0.4, CuIn0.7Ga0.3Se0.4Te1.6 and CuIn0.7Ga0.3Se2 thin films. The energy bandgap values decrease with increasing telluride (Te) doping ratio in mixed CuIn0.7Ga0.3(Se1-xTex)2 films. This affects nonlinear characteristics and ultrafast dynamics of amorphous thin films. Ultrafast pump-probe experiments indicated that decreasing of bandgap values with increasing the Te amount switches from the excited state absorption signals to ultrafast bleaching signals. Open aperture Z-scan experiments show that nonlinear absorption properties enhance with decreasing bandgaps values for 65 ps pulse duration at 1064 nm. Highest nonlinear absorption coefficient was found for CuIn0.7Ga0.3Te2 thin film due to having the smallest energy bandgap.

CHROMOSPHERIC EVAPORATION IN AN X1.0 FLARE ON 2014 MARCH 29 OBSERVED WITH IRIS AND EIS

Energy Technology Data Exchange (ETDEWEB)

Li, Y.; Ding, M. D. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Qiu, J. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Cheng, J. X., E-mail: yingli@nju.edu.cn [Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 (China)

2015-09-20

Chromospheric evaporation refers to dynamic mass motions in flare loops as a result of rapid energy deposition in the chromosphere. These motions have been observed as blueshifts in X-ray and extreme-ultraviolet (EUV) spectral lines corresponding to upward motions at a few tens to a few hundreds of km s{sup −1}. Past spectroscopic observations have also revealed a dominant stationary component, in addition to the blueshifted component, in emission lines formed at high temperatures (∼10 MK). This is contradictory to evaporation models predicting predominant blueshifts in hot lines. The recently launched Interface Region Imaging Spectrograph (IRIS) provides high-resolution imaging and spectroscopic observations that focus on the chromosphere and transition region in the UV passband. Using the new IRIS observations, combined with coordinated observations from the EUV Imaging Spectrometer, we study the chromospheric evaporation process from the upper chromosphere to the corona during an X1.0 flare on 2014 March 29. We find evident evaporation signatures, characterized by Doppler shifts and line broadening, at two flare ribbons that are separating from each other, suggesting that chromospheric evaporation takes place in successively formed flaring loops throughout the flare. More importantly, we detect dominant blueshifts in the high-temperature Fe xxi line (∼10 MK), in agreement with theoretical predictions. We also find that, in this flare, gentle evaporation occurs at some locations in the rise phase of the flare, while explosive evaporation is detected at some other locations near the peak of the flare. There is a conversion from gentle to explosive evaporation as the flare evolves.

Morphological analysis of GeTe in inline phase change switches

Energy Technology Data Exchange (ETDEWEB)

King, Matthew R., E-mail: matthew.king2@ngc.com [Northrop Grumman Electronic Systems, Advanced Concepts and Technologies Division, 1212 Winterson Rd., Linthicum, Maryland 21090 (United States); Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); El-Hinnawy, Nabil [Northrop Grumman Electronic Systems, Advanced Concepts and Technologies Division, 1212 Winterson Rd., Linthicum, Maryland 21090 (United States); Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Salmon, Mike; Gu, Jitty [Evans Analytical Group, 628 Hutton St., Raleigh, North Carolina 27606 (United States); Wagner, Brian P.; Jones, Evan B.; Howell, Robert S.; Nichols, Doyle T.; Young, Robert M. [Northrop Grumman Electronic Systems, Advanced Concepts and Technologies Division, 1212 Winterson Rd., Linthicum, Maryland 21090 (United States); Borodulin, Pavel [Northrop Grumman Electronic Systems, Advanced Concepts and Technologies Division, 1212 Winterson Rd., Linthicum, Maryland 21090 (United States); Department of Electrical and Computer Engineering, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)

2015-09-07

Crystallization and amorphization phenomena in indirectly heated phase change material-based devices were investigated. Scanning transmission electron microscopy was utilized to explore GeTe phase transition processes in the context of the unique inline phase change switch (IPCS) architecture. A monolithically integrated thin film heating element successfully converted GeTe to ON and OFF states. Device cycling prompted the formation of an active area which sustains the majority of structural changes during pulsing. A transition region on both sides of the active area consisting of polycrystalline GeTe and small nuclei (<15 nm) in an amorphous matrix was also observed. The switching mechanism, determined by variations in pulsing parameters, was shown to be predominantly growth-driven. A preliminary model for crystallization and amorphization in IPCS devices is presented.

Morphological analysis of GeTe in inline phase change switches

International Nuclear Information System (INIS)

King, Matthew R.; El-Hinnawy, Nabil; Salmon, Mike; Gu, Jitty; Wagner, Brian P.; Jones, Evan B.; Howell, Robert S.; Nichols, Doyle T.; Young, Robert M.; Borodulin, Pavel

2015-01-01

Crystallization and amorphization phenomena in indirectly heated phase change material-based devices were investigated. Scanning transmission electron microscopy was utilized to explore GeTe phase transition processes in the context of the unique inline phase change switch (IPCS) architecture. A monolithically integrated thin film heating element successfully converted GeTe to ON and OFF states. Device cycling prompted the formation of an active area which sustains the majority of structural changes during pulsing. A transition region on both sides of the active area consisting of polycrystalline GeTe and small nuclei (<15 nm) in an amorphous matrix was also observed. The switching mechanism, determined by variations in pulsing parameters, was shown to be predominantly growth-driven. A preliminary model for crystallization and amorphization in IPCS devices is presented

Transient effects of ionizing radiation in Si, InGaAsP, GaAlSb, and Ge photodiodes

International Nuclear Information System (INIS)

Wiczer, J.J.; Barnes, C.E.; Dawson, L.R.

1980-01-01

Certain military applications require the continuous operation of optoelectronic information transfer systems during exposure to ionizing radiation. In such an environment the optical detector can be the system element which limits data transmission. We report here the measured electrical and optical characteristics of an irradiation tolerant photodiode fabricated from a double heterojunction structure in the gallium aluminum antimonide (GaAlSb) ternary semiconductor system. A series of tests at Sandia Laboratories' Relativistic Electron Beam Accelerator (REBA) subjected this device and commercially available photodiodes (made from silicon, germanium, and indium gallium arsenide phosphide) to dose rate levels of 10 7 to 10 8 rads/sec. The results of these tests show that the thin GaAlSb double heterojunction photodiode structure generates significantly less unwanted radiation induced current density than that of the next best commercial device

Local order origin of thermal stability enhancement in amorphous Ag doping GeTe

Energy Technology Data Exchange (ETDEWEB)

Xu, L.; Li, Y.; Yu, N. N.; Zhong, Y. P.; Miao, X. S., E-mail: miaoxs@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology (HUST), Wuhan 430074 (China); School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

2015-01-19

We demonstrate the impacts of Ag doping on the local atomic structure of amorphous GeTe phase-change material. The variations of phonon vibrational modes, boding nature, and atomic structure are shown by Raman, X-ray photoelectron spectroscopy, and ab initio calculation. Combining the experiments and simulations, we observe that the number of Ge atoms in octahedral site decreases and that in tetrahedral site increases. This modification in local order of GeTe originating from the low valence element will affect the crystallization behavior of amorphous GeTe, which is verified by differential scanning calorimetry and transmission electron microscope results. This work not only gives the analysis on the structural change of GeTe with Ag dopants but also provides a method to enhance the thermal stability of amorphous phase-change materials for memory and brain-inspired computing applications.

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...

Germanium diffusion with vapor-phase GeAs and oxygen co-incorporation in GaAs

Science.gov (United States)

Wang, Wei-Fu; Cheng, Kai-Yuan; Hsieh, Kuang-Chien

2018-01-01

Vapor-phase germanium diffusion has been demonstrated in Zn-doped and semi-insulating GaAs in sealed ampoules with GeAs powders and excess arsenic. Secondary-ion-mass spectroscopy (SIMS) profiles indicate the presence of unintentional co-incorporation of oxygen in high densities (>1017/cm3) along with diffused germanium donors whose concentration (>>1018/cm3) determined by electro-chemical capacitance-voltage (ECV) profiler shows significant compensation near the surface. The source of oxygen mainly originates from the GeAs powder which contains Ge-O surface oxides. Variable-temperature photoluminescence (PL) shows that in GeAs-diffused samples, a broad peak ranging from 0.86-1.38 eV with the peak position around 1.1 eV predominates at low temperatures while the near band-edge luminescence quenches. The broad band is attributed to the GeGa-VGa self-activated (SA) centers possibly associated with nearby oxygen-related defect complex, and its luminescence persists up to 400 K. The configurational-coordinate modeling finds that the SA defect complex has a thermal activation energy of 150-180 meV and a vibrational energy 26.8 meV. The presence of oxygen does not much affect the SA emission intensity but may have influenced the peak position, vibration frequency and activation energy as compared to other common donor-VGa defects in GaAs.

Germanium diffusion with vapor-phase GeAs and oxygen co-incorporation in GaAs

Directory of Open Access Journals (Sweden)

Wei-Fu Wang

2018-01-01

Full Text Available Vapor-phase germanium diffusion has been demonstrated in Zn-doped and semi-insulating GaAs in sealed ampoules with GeAs powders and excess arsenic. Secondary-ion-mass spectroscopy (SIMS profiles indicate the presence of unintentional co-incorporation of oxygen in high densities (>1017/cm3 along with diffused germanium donors whose concentration (>>1018/cm3 determined by electro-chemical capacitance-voltage (ECV profiler shows significant compensation near the surface. The source of oxygen mainly originates from the GeAs powder which contains Ge-O surface oxides. Variable-temperature photoluminescence (PL shows that in GeAs-diffused samples, a broad peak ranging from 0.86-1.38 eV with the peak position around 1.1 eV predominates at low temperatures while the near band-edge luminescence quenches. The broad band is attributed to the GeGa-VGa self-activated (SA centers possibly associated with nearby oxygen-related defect complex, and its luminescence persists up to 400 K. The configurational-coordinate modeling finds that the SA defect complex has a thermal activation energy of 150-180 meV and a vibrational energy 26.8 meV. The presence of oxygen does not much affect the SA emission intensity but may have influenced the peak position, vibration frequency and activation energy as compared to other common donor-VGa defects in GaAs.

GaAs/Ge solar panels for the SAMPEX program

Science.gov (United States)

Dobson, Rodney; Kukulka, Jerry; Dakermanji, George; Roufberg, Lew; Ahmad, Anisa; Lyons, John

1992-01-01

GaAs based solar cells have been developed for spacecraft use for several years. However, acceptance and application of these cells for spacecraft missions has been slow because of their high cost and concerns about their integration onto solar panels. Spectrolab has now completed fabrication of solar panels with GaAs/Ge solar cells for a second space program. This paper will focus on the design, fabrication and test of GaAs/Ge solar panels for the Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX) Program.

Impact of sulfur content on structural and optical properties of Ge20Se80-xSx chalcogenide glasses thin films

Science.gov (United States)

Dongol, M.; Elhady, A. F.; Ebied, M. S.; Abuelwafa, A. A.

2018-04-01

Chalcogenide system Ge20Se80-xSx (x = 0, 15 and 30%) thin films were prepared by thermal evaporation technique. The amorphous state of the samples was confirmed according to XRD. The structural changes occurring upon replacement Se by S was investigated using Raman spectroscopy. The optical properties of the as-deposited Ge20Se80-xSx thin films have been studied by analysis the transmittance T(λ) measured at room temperature in the wavelength range 200-2500 nm using Swanepoel's method. Urbach energy (Ee) and optical band gap (Eg) were strongly affected by sulfur concentration in the sample. The refractive index evaluated through envelope method was extrapolated by Cauchy dispersion relationship over the whole spectral range. Moreover, the dispersion of refractive index was analyzed in terms of the single-oscillator Wemple-Di Domenico model. The third-order nonlinear susceptibility (χ(3)) and nonlinear refractive index (n2) were calculated and discussed for different Ge20Se80-xSx (x = 0, 15 and 30%).

LHC constraints on Yukawa unification in SO(10)

Energy Technology Data Exchange (ETDEWEB)

Badziak, Marcin [Cambridge Univ. (United Kingdom). Centre for Mathematical Sciences; Cambridge Univ. (United Kingdom). Cavendish Lab.; Sakurai, Kazuki [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2011-12-15

LHC constraints on the recently proposed SUSY SO(10) GUT model with top-bottom-tau Yukawa uni cation are investigated. In this model, various phenomenological constraints are in concord with Yukawa uni cation thanks to the negative sign of {mu}, D-term splitting in the soft scalar masses and non-universal gaugino masses generated by non-zero F-term in a 24-dimensional representation of SU(5) is contained in SO(10). After discussing the impact of the CP-odd Higgs boson mass bound on this model, we provide a detailed analysis of the recent direct SUSY searches performed by ATLAS and investigate the constraints on this SO(10) model. At 95% confidence level, the lower limit on the gluino mass is found at 675 GeV. Assuming an integrated luminosity of 10 fb{sup -1}, this bound may be extended to 1.1 TeV if the right-handed down squark is lighter than about 1 TeV. (orig.)

Growth of BaSi2 film on Ge(100) by vacuum evaporation and its photoresponse properties

Science.gov (United States)

Trinh, Cham Thi; Nakagawa, Yoshihiko; Hara, Kosuke O.; Kurokawa, Yasuyoshi; Takabe, Ryota; Suemasu, Takashi; Usami, Noritaka

2017-05-01

We have successfully grown a polycrystalline orthorhombic BaSi2 film on a Ge(100) substrate by an evaporation method. Deposition of an amorphous Si (a-Si) film on the Ge substrate prior to BaSi2 evaporation plays a critical role in obtaining a high-quality BaSi2 film. By controlling substrate temperature and the thickness of the a-Si film, a crack-free and single-phase polycrystalline orthorhombic BaSi2 film with a long carrier lifetime of 1.5 µs was obtained on Ge substrates. The photoresponse property of the ITO/BaSi2/Ge/Al structure was clearly observed, and photoresponsivity was found to increase with increasing substrate temperature during deposition of a-Si. Furthermore, the BaSi2 film grown on Ge showed a higher photoresponsivity than that grown on Si, indicating the potential application of evaporated BaSi2 on Ge to thin-film solar cells.

In-situ optical emission spectroscopy for a better control of hybrid sputtering/evaporation process for the deposition of Cu(In,Ga)Se{sub 2} layers

Energy Technology Data Exchange (ETDEWEB)

Posada, Jorge; Jubault, Marie [Institute of Research and Development on Photovoltaic Energy (IRDEP), EDF-CNRS-Chimie ParisTech, UMR 7174, 6 Quai Watier, 78401 Chatou (France); Bousquet, Angélique; Tomasella, Eric [Clermont Université, Université Blaise Pascal, Institute of Chemistry of Clermont-Ferrand (ICCF), CNRS-UMR 6296, 24 Avenue des Landais, 63171 Aubière (France); Lincot, Daniel [Institute of Research and Development on Photovoltaic Energy (IRDEP), EDF-CNRS-Chimie ParisTech, UMR 7174, 6 Quai Watier, 78401 Chatou (France)

2015-05-01

In this work, we have developed a hybrid one-step co-sputtering/evaporation Cu(In,Ga)Se{sub 2} (CIGS) process, where Cu, In and Ga are sputtered simultaneously with the thermal evaporation of selenium, thus avoiding the H{sub 2}Se use. An appropriate control of the selenium flux is very important to prevent the target poisoning and hence some material flux variations. Indeed, the control of the CIGS composition must be rigorous to ensure reproducible solar cell properties. In this regard, a study of the correlations between plasma species and thin film composition, structure and morphology has been performed by varying power values and Se evaporation temperature in the 170 to 230 °C range. We started by studying the plasma with a powerful technique: optical emission spectroscopy, following light emissions from different plasma species: sputtered Cu, Ga, In but also evaporated Se. Hence, we determined the Se flow threshold avoiding target poisoning and the main parameter controlling the CIGS composition. Obviously, we also focused our interest on the material. We measured film composition and thickness of the samples with X-ray fluorescence and by energy dispersive X-ray. Different phases formed during the process were identified by Raman spectroscopy and X-ray diffraction. The optoelectronic cell properties showed promising efficiency of 10.3% for an absorber with composition ratios of [Cu]/([In] + [Ga]) = 1.02 and [Ga]/([In] + [Ga]) = 0.44. Finally, this work shows that we are able to control this hybrid process and thus the structure and composition of CIGS thin film for industrial transfer in the photovoltaic field. - Highlights: • We have developed a hybrid one-step co-sputtering/evaporation Cu(In,Ga)Se{sub 2} process. • Correlations between plasma species and thin film composition have been performed. • We determined the Se flow threshold avoiding target poisoning. • Efficient small-area CIGS cells with 10.3% efficiency were fabricated.

Synthesis and first-principle calculations of the structural and electronic properties of Ge-substituted type-VIII Ba{sub 8}Ga{sub 16}Sn{sub 30} clathrate

Energy Technology Data Exchange (ETDEWEB)

Shen, Lanxian [Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Yunnan Provincial Renewable Energy Engineering Key Lab, Solar Energy Research Institution, Yunnan Normal University, Kunming 650500 (China); Li, Decong [College of Optoelectronic Engineering, Yunnan Open University, Kunming 650500 (China); Liu, Hongxia; Liu, Zuming [Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Yunnan Provincial Renewable Energy Engineering Key Lab, Solar Energy Research Institution, Yunnan Normal University, Kunming 650500 (China); Deng, Shukang, E-mail: skdeng@126.com [Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Yunnan Provincial Renewable Energy Engineering Key Lab, Solar Energy Research Institution, Yunnan Normal University, Kunming 650500 (China)

2016-12-01

In this study, the structural and electronic structural properties of Ba{sub 8}Ga{sub 16}Sn{sub 30−x}Ge{sub x} (0≤x≤30) are determined by the first-principle method on the basis of density functional theory. Consistent with experimental findings, calculated results reveal that Ge atoms preferentially occupy the 2a and 24g sites in these compounds. As the content of Ge in Ge-substituted clathrate is increased, the lattice parameter is decreased, and the structural stability is enhanced. The bandgaps of the compound at 1≤x≤10 are smaller than those of Ba{sub 8}Ga{sub 16}Sn{sub 30}. By contrast, the bandgaps of the compound at x>10 are larger than those of Ba{sub 8}Ga{sub 16}Sn{sub 30}. The substitution of Ge for Sn affects p-type conductivity but not n-type conductivity. As Ge content increases, the whole conduction band moves to the direction of high energy, and the density of states of valence-band top decreases. The calculated potential energy versus displacement of Ba indicates that the vibration energy of this atom increases as cage size decreases. Because Ge substitution also affects clathrate structural symmetry, the distance of Ba atom deviation from the center of the cage initially increases and subsequently decreases as the Ge content increases.

High-temperature operation of self-assembled GaInNAs/GaAsN quantum-dot lasers grown by solid-source molecular-beam epitaxy

International Nuclear Information System (INIS)

Liu, C.Y.; Yoon, S.F.; Sun, Z.Z.; Yew, K.C.

2006-01-01

Self-assembled GaInNAs/GaAsN single layer quantum-dot (QD) lasers grown using solid-source molecular-beam epitaxy have been fabricated and characterized. Temperature-dependent measurements have been carried out on the GaInNAs QD lasers. The lowest obtained threshold current density in this work is ∼1.05 kA/cm 2 from a GaInNAs QD laser (50x1700 μm 2 ) at 10 deg. C. High-temperature operation up to 65 deg. C was also demonstrated from an unbonded GaInNAs QD laser (50x1060 μm 2 ), with high characteristic temperature of 79.4 K in the temperature range of 10-60 deg. C

CLIC, a 0.5 to 5 TeV e$^{\\pm}$ Compact Linear Collider

CERN Document Server

Delahaye, J P; Braun, Hans Heinrich; Carron, G; Chautard, F; Coosemans, Williame; Corsini, R; D'Amico, T E; Dehler, M; Godot, J C; Guignard, Gilbert; Hagel, J; Hutchins, S; Johnson, C D; Jensen, E; Kamber, I; Millich, Antonio; Pearce, P; Potier, J P; Riche, A J; Rinolfi, Louis; Schulte, Daniel; Suberlucq, Guy; Thorndahl, L; Valentini, M; Warner, D J; Wilson, Ian H; Wuensch, Walter; Napoly, O; Raubenheimer, T O; Ruth, Ronald D

1998-01-01

The CLIC study of a high energy (0.5 - 5 TeV), high luminosity (10^34 - 10^35 cm^-2 sec^-1) e± linear collider is presented. Beam acceleration using high frequency (30 GHz) normal-conducting structure s operating at high accelerating fields (100 to 200 MV/m) significantly reduces the length and, in consequence the cost of the linac. Based on new beam and linac parameters derived from a recently dev eloped set of general scaling laws for linear colliders, the beam stability is shown to be similar to lower frequency designs in spite of the strong wake-field dependency on frequency. A new cost effe ctive and very efficient drive beam generation scheme for RF power production by the so-called "Two Beam Acceleration (TBA)" method is described. It uses a conventional thermionic gun and a fully-load ed normal-conducting linac operating at low frequency (937 MHz) to generate and accelerate the drive beam bunches and RF multiplication by funneling in compressor rings to produce the desired bunch st ructure. Recent 30...

View of the WA10 set-up

CERN Multimedia

CERN PhotoLab

1977-01-01

The WA10 experiment by the Geneva-Lausanne Collaboration was set-up in the H5 beam (unseparated, up to 50 GeV/c) to study K+-p --> K0pi+-p and other reactions of similar topology, and the energy dependence of resonance production.

First Fermi-LAT Catalog of Sources above 10 GeV (1FHL)

Data.gov (United States)

National Aeronautics and Space Administration — This catalog of LAT sources above 10 GeV reports the locations, spectra, and variability properties of the 514 sources significantly detected in this range during...

Ferromagnetism in Fe{sub 3-x-y}Ni{sub x}GeTe{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Stahl, Juliane; Johrendt, Dirk [Muenchen Univ. (Germany). Dept. Chemie; Pomjakushin, Vladimir [Paul Scherrer Institute, Villigen (Switzerland). Lab. for Neutron Scattering

2016-07-01

Polycrystalline samples of Fe{sub 3-y}GeTe{sub 2} (0.08 ≤ y ≤ 0.29) and the solid solutions Fe{sub 3-x-y}Ni{sub x}GeTe{sub 2} (0.24 ≤ x ≤ 1.32; 0.14 ≤ y ≤ 0.41) were synthesized at 898-973 K in a resistance furnace and characterized by X-ray and neutron powder diffraction with Rietveld analysis (Fe{sub 3}GeTe{sub 2} type, P6{sub 3}/mmc, a = 402.665(3), c = 1632.820(14) pm for x = 0, y = 0.08). Fe{sub 3}Ge layers with planar FeGe hexagons and additional iron atoms above and below the rings are separated by double layers of tellurium atoms. Fe{sub 3}GeTe{sub 2} is ferromagnetic below T{sub C} = 230 K with magnetic moments aligned along the c axis. T{sub C} depends on the iron content and decreases with increasing iron vacancies continuously to 153 K in Fe{sub 2.71}GeTe{sub 2}. Further reduction of T{sub C} is possible by nickel substitution until magnetic ordering is nearly absent in Fe{sub 1.33}Ni{sub 1.32}GeTe{sub 2}. The suppression of the magnetic ordering is caused by random dilution of the magnetic iron atoms either by vacancies or by non-magnetic nickel atoms.

On the choice of beam polarization in e{sup +}e{sup -} → ZZ/Zγ and anomalous triple gauge-boson couplings

Energy Technology Data Exchange (ETDEWEB)

Rahaman, Rafiqul; Singh, Ritesh K. [Indian Institute of Science Education and Research Kolkata, Department of Physical Sciences, Mohanpur (India)

2017-08-15

The anomalous trilinear gauge couplings of Z and γ are studied in e{sup +}e{sup -} → ZZ/Zγ with longitudinal beam polarizations using a complete set of polarization asymmetries for the Z boson. We quantify the goodness of the beam polarization in terms of the likelihood and find the best choice of e{sup -} and e{sup +} polarizations to be (+0.16, -0.16), (+0.09, -0.10) and (+0.12, -0.12) for ZZ, Zγ and combined processes, respectively. Simultaneous limits on anomalous couplings are obtained for these choices of beam polarizations using Markov-Chain-Monte-Carlo (MCMC) for an e{sup +}e{sup -} collider running at √(s) = 500 GeV and L = 100 fb{sup -1}. We find the simultaneous limits for these beam polarizations to be comparable with each other and also comparable with the unpolarized beam case. (orig.)

Preparation and observation of an artifact-free Ge2Sb2Te5 TEM specimen by the small angle cleavage technique

International Nuclear Information System (INIS)

Kim, M.S.; Kim, H.G.

2006-01-01

The amorphous Ge 2 Sb 2 Te 5 thin film for the application to the non-volatile memory device was prepared by the pulsed laser deposition on a SiO2/Si substrate. The amorphous Ge 2 Sb 2 Te 5 which has the T C around 150 deg. C is readily crystallized when exposed to a comparable heat such as the Ar beam irradiation during the conventional ion milling process. Retaining its amorphous initial phase is important in order to precisely observe and understand the crystallization behaviour whether it be the sample for a pure materialistic research or applied into the device. To avoid such deterioration of the film's amorphous nature, the complete mechanical TEM specimen preparation which is called the small angle cleavage technique (SACT) was adopted to show thermally undisturbed, an artifact-free amorphous Ge 2 Sb 2 Te 5 TEM specimen. The two distinctive amorphous and crystalline phases has been observed by the HRTEM study

Pumping experiment of water on B and LaB6 films with electron beam evaporator

International Nuclear Information System (INIS)

Mori, Takahiro; Hanaoka, Yutaka; Akaishi, Kenya; Kubota, Yusuke; Motojima, Osamu; Mushiaki, Motoi; Funato, Yasuyuki.

1992-10-01

Pumping characteristics of water vapor on boron and lanthanum hexaboride films formed with an electron beam evaporator have been investigated in high vacuum of a pressure region between 10 -4 and 10 -3 Pa. Measured initial maximum pumping speeds of water for fresh B and LaB 6 films on substrates with a deposition amount from 2.3 x 10 21 to 6.7 x 10 21 molecules·m -2 are 3.2 ∼ 4.9 m 3 ·s -1 ·m -2 , and maximum saturation amounts of adsorbed water on these films are 2.9 x 10 20 ∼ 1.3 x 10 21 H 2 O molecules·m -2 . (author)

Crystallization kinetics of GeTe phase-change thin films grown by pulsed laser deposition

Science.gov (United States)