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Sample records for ge sn pb

  1. Comparative studies of clustering effect, electronic and optical properties for GePb and GeSn alloys with low Pb and Sn concentration

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Wenqi [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); School of Applied Science, Beijing Information Science and Technology University, Beijing 100101 (China); Cheng, Buwen, E-mail: cbw@semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Xue, Chunlai; Li, Chuanbo [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China)

    2014-06-15

    The first principle calculations are performed to study the impurity clustering effect, electronic and optical properties of GePb and GeSn alloys. The calculated results show that for a given concentration, the maximum impurity (Sn or Pb) clustered configuration is the most stable equilibrium structure (corresponding to the lowest total energy) which has the highest band gap. The calculated lattice constants and bulk modulus agree well with experimental and others’ theoretical values. The calculated band structures of virtual crystal structure and super-cell structure both indicate that GePb alloys undergo a transition from indirect to direct band gap as Pb concentration increases, and the transitional concentration is much lower than that of GeSn alloy. This conclusion indicates that GePb alloy can be a very prospective material for fabricating group-IV laser. The density of states and charge density maps of GeSn and GePb alloys are analyzed comparatively. For optical properties, the dielectric function, absorption spectrum, reflectivity, refractive index and loss function of Ge{sub 22}Sn{sub 2} and Ge{sub 22}Pb{sub 2} are investigated in detail.

  2. 125Te NMR chemical-shift trends in PbTe–GeTe and PbTe–SnTe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Njegic, Bosiljka [Ames Laboratory; Levin, Evgenii M. [Ames Laboratory; Schmidt-Rohr, Klaus [Ames Laboratory

    2013-10-08

    Complex tellurides, such as doped PbTe, GeTe, and their alloys, are among the best thermoelectric materials. Knowledge of the change in 125Te NMR chemical shift due to bonding to dopant or “solute” atoms is useful for determination of phase composition, peak assignment, and analysis of local bonding. We have measured the 125Te NMR chemical shifts in PbTe-based alloys, Pb1-xGexTe and Pb1-xSnxTe, which have a rocksalt-like structure, and analyzed their trends. For low x, several peaks are resolved in the 22-kHz MAS 125Te NMR spectra. A simple linear trend in chemical shifts with the number of Pb neighbors is observed. No evidence of a proposed ferroelectric displacement of Ge atoms in a cubic PbTe matrix is detected at low Ge concentrations. The observed chemical shift trends are compared with the results of DFT calculations, which confirm the linear dependence on the composition of the first-neighbor shell. The data enable determination of the composition of various phases in multiphase telluride materials. They also provide estimates of the 125Te chemical shifts of GeTe and SnTe (+970 and +400±150 ppm, respectively, from PbTe), which are otherwise difficult to access due to Knight shifts of many hundreds of ppm in neat GeTe and SnTe.

  3. 125Te NMR chemical-shift trends in PbTe-GeTe and PbTe-SnTe alloys.

    Science.gov (United States)

    Njegic, B; Levin, E M; Schmidt-Rohr, K

    2013-01-01

    Complex tellurides, such as doped PbTe, GeTe, and their alloys, are among the best thermoelectric materials. Knowledge of the change in (125)Te NMR chemical shift due to bonding to dopant or "solute" atoms is useful for determination of phase composition, peak assignment, and analysis of local bonding. We have measured the (125)Te NMR chemical shifts in PbTe-based alloys, Pb1-xGexTe and Pb1-xSnxTe, which have a rocksalt-like structure, and analyzed their trends. For low x, several peaks are resolved in the 22-kHz MAS (125)Te NMR spectra. A simple linear trend in chemical shifts with the number of Pb neighbors is observed. No evidence of a proposed ferroelectric displacement of Ge atoms in a cubic PbTe matrix is detected at low Ge concentrations. The observed chemical shift trends are compared with the results of DFT calculations, which confirm the linear dependence on the composition of the first-neighbor shell. The data enable determination of the composition of various phases in multiphase telluride materials. They also provide estimates of the (125)Te chemical shifts of GeTe and SnTe (+970 and +400±150 ppm, respectively, from PbTe), which are otherwise difficult to access due to Knight shifts of many hundreds of ppm in neat GeTe and SnTe.

  4. Rapid solidification and dendrite growth of ternary Fe-Sn-Ge and Cu-Pb-Ge monotectic alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The phase separation and dendrite growth characteristics of ternary Fe-43.9%Sn- 10%Ge and Cu-35.5%Pb-5%Ge monotectic alloys were studied systematically by the glass fluxing method under substantial undercooling conditions. The maximum undercoolings obtained in this work are 245 and 257 K, respectively, for these two alloys. All of the solidified samples exhibit serious macrosegregation, indicating that the homogenous alloy melt is separated into two liquid phases prior to rapid solidification. The solidification structures consist of four phases including α-Fe, (Sn), FeSn and FeSn2 in Fe-43.9%Sn-10%Ge ternary alloy, whereas only (Cu) and (Pb) solid solution phases in Cu-35.5%Pb-5%Ge alloy under different undercool- ings. In the process of rapid monotectic solidification, α-Fe and (Cu) phases grow in a dendritic mode, and the transition "dendrite→monotectic cell" happens when alloy undercoolings become sufficiently large. The dendrite growth velocities of α-Fe and (Cu) phases are found to increase with undercooling according to an exponential relation.

  5. Rapid solidification and dendrite growth of ternary Fe-Sn-Ge and Cu-Pb-Ge monotectic alloys

    Institute of Scientific and Technical Information of China (English)

    ZHANG XueHua; RUAN Ying; WANG WeiLi; WEI BingBo

    2007-01-01

    The phase separation and dendrite growth characteristics of ternary Fe-43.9%Sn- 10%Ge and Cu-35.5%Pb-5%Ge monotectic alloys were studied systematically by the glass fluxing method under substantial undercooling conditions. The maximum undercoolings obtained in this work are 245 and 257 K, respectively, for these two alloys. All of the solidified samples exhibit serious macrosegregation, indicating that the homogenous alloy melt is separated into two liquid phases prior to rapid solidification. The solidification structures consist of four phases including α-Fe, (Sn), FeSn and FeSn2 in Fe-43.9%Sn-10%Ge ternary alloy, whereas only (Cu) and (Pb) solid solution phases in Cu-35.5%Pb-5%Ge alloy under different undercoolings. In the process of rapid monotectic solidification, α-Fe and (Cu) phases grow in a dendritic mode, and the transition "dendrite→monotectic cell" happens when alloy undercoolings become sufficiently large. The dendrite growth velocities of α-Fe and (Cu) phases are found to increase with undercooling according to an exponential relation.

  6. Dielectric behavior of a-Sn-Se-Pb-Ge chalcogenide glass

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Prashant, E-mail: prashantshrm5@gmail.com; Modgil, Vivek; Choudhary, Shobhana; Nidhi, A. V.; Rangra, V. S. [Department of Physics, Himachal Pradesh University, Summerhill Shimla 171005 (India)

    2015-05-15

    The bulk material Sn{sub 8}Se{sub 74}Pb{sub 18-x}Ge{sub x}(7≤x≤11) has been prepared by melt quenching technique. The viterous and glassy nature have been confirmed by X-Ray Diffraction (XRD) and Differential Scanning Calorimetery (DSC) techniques respectively. The material exhibits the good thermal stability and high value of glass transition temperature. The dielectric behavior has been studied in frequency range 50Hz-1MHz, using pallet method. The universal dielectric behaviour of amorphous semiconductors has been observed for the glass system. The compositional dependence of dielectric behavior has also been observed.

  7. The Binary Anion Clusters of Ge/Sn, Ge/Pb, Sn/Pb, Co/Ge, Co/Sn and Co/Pb%锗分族元素二元团簇及其与Co形成的团簇离子

    Institute of Scientific and Technical Information of China (English)

    张霞; 唐紫超; 高振

    2003-01-01

    通过比较激光烧蚀E1/E2(代表Ge/Sn,Ge/Pb和Sn/Pb)和Co/E(E为Ge、Sn、Pb)混合样品形成的二元团簇负离子飞行时间质谱分布和谱峰的相对强度及形成的幻数团簇离子峰,发现E1/E2二元团簇离子中原子量大的锗分族元素在团簇离子中占主要组分,而原子量小的元素则少量掺杂,其组成和分布特点说明其结构和性质与纯E团簇离子相似,可能的结构为该类负离子团簇所有原子都在笼结构的骨架上;对于二元团簇离子GeSn-9、GePb-9和SnPb-9其结构可能是双帽反四棱柱构型,只是每个原子均为骨架的一部分.而对激光烧蚀过渡金属钴与锗分族元素的混合物的研究发现,反应形成了丰富的Co/E二元合金团簇负离子,分析发现该类簇离子为钴内包覆于E(锗分族元素)笼状结构.幻数离子CoGe-10、CoSn-10和CoPb-10可能具有双帽四角反棱柱结构,而CoPb-12可能具有二十面体构型,钴原子均为笼状结构的中心.

  8. Dielectric behavior of a-Sn-Se-Pb-Ge chalcogenide glass

    Science.gov (United States)

    Kumar, Prashant; Modgil, Vivek; Choudhary, Shobhana; Nidhi, A. V.; Rangra, V. S.

    2015-05-01

    The bulk material Sn8Se74Pb18-xGex(7≤x≤11) has been prepared by melt quenching technique. The viterous and glassy nature have been confirmed by X-Ray Diffraction (XRD) and Differential Scanning Calorimetery (DSC) techniques respectively. The material exhibits the good thermal stability and high value of glass transition temperature. The dielectric behavior has been studied in frequency range 50Hz-1MHz, using pallet method. The universal dielectric behaviour of amorphous semiconductors has been observed for the glass system. The compositional dependence of dielectric behavior has also been observed.

  9. Electronic and Optical Properties of Ca3MN (M = Ge, Sn, Pb, P, As, Sb and Bi) Antiperovskite Compounds

    Science.gov (United States)

    Iqbal, Samad; Murtaza, G.; Khenata, R.; Mahmood, Asif; Yar, Abdullah; Muzammil, M.; Khan, Matiullah

    2016-08-01

    The electronic and optical properties of cubic antiperovskites Ca3MN (M = Ge, Sn, Pb, P, As, Sb and Bi) were investigated by applying the full potential linearized augmented plane wave plus local orbitals (FP-LAPW + lo) scheme based on density functional theory. Different exchange correlation potentials were adopted for the calculations. The results of band structure and density of states show that, by changing the central anion of Ca3MN, the nature of the materials change from metallic (Ca3GeN, Ca3SnN, Ca3PbN) to semiconducting with small band gaps (Ca3SbN and Ca3BiN) to insulating (Ca3PN and Ca3AsN). The optical properties such as dielectric function, absorption coefficient, optical conductivity, reflectivity and refractive indices have also been calculated. The results reveal that all the studied compounds are optically active in the visible and ultraviolet energy regions, and therefore can be effectively utilized for optoelectronic devices.

  10. New members of the A2 M ‧ M2″ structure family (A=Ca, Sr, Yb, La; M ‧ = In , Sn , Pb; M ″ = Si , Ge)

    Science.gov (United States)

    Jehle, Michael; Dürr, Ines; Fink, Saskia; Lang, Britta; Langenmaier, Michael; Steckhan, Julia; Röhr, Caroline

    2015-01-01

    The new mixed tetrelides Sr2PbGe2 and Yb2SnGe2, several mixed Ca/Sr (AII) germanides A2II (Sn , Pb)Ge2 and two polymorphs of La2 InSi2 represent new members of the general structure family of ternary alkaline-earth/lanthanoid main group silicides/germanides A2 M ‧ M2″ (M ‧ = In , Sn , Pb ; M ″ = Si , Ge). All compounds were synthesized from melts of the elements and their crystal structures have been determined by means of single crystal X-ray diffraction. Sr2PbGe2 (Cmmm, a=402.36(11), b=1542.3(4), c=463.27(10) pm) crystallizes with the Mn2AlB2 -type structure. In exhibiting infinite planar Ge zig-zag chains, it represents one border of the compound series. The other borderline case, where only [Ge2 ] dumbbells are left as Ge building units, is represented by the Ca/Yb tin germanides Ca2SnGe2 and Yb2SnGe2 (Mo2FeB2 -type; P4/mbm, a=748.58(13)/740.27(7), c=445.59(8)/435.26(5) pm). In between these two border structures compounds with variable Si/Ge chain lengths could be obtained by varying the averaged size of the AII cations: Ca0.45Sr1.55PbGe2 (new structure type; Pbam, a=791.64(5), b=2311.2(2), c=458.53(3) pm) contains planar six-membered chain segments [Ge6 ]. Tetrameric pieces [Ge4 ] are the conspicuous structure elements in Ca1.16Sr0.84SnGe2 and La2 InSi2 (La2 InNi2 -type; Pbam, a=781.01(2)/762.01(13), b=1477.95(3)/1494.38(6), c=457.004(9)/442.1(3) pm). The tetragonal form of 'La2 In Si2‧ (exact composition: La2In1.07Si1.93, P4/mbm, a=1309.11(12), c=443.32(4) pm) also crystallizes in a new structure type, containing only [Si3 ] trimers as cutouts of the planar chains. In all structures the Si/Ge zig-zag chains/chain segments are connected by In/Sn/Pb atoms to form planar M layers, which are separated by pure A layers. Band structure calculations within the FP-LAPW DFT approach together with the Zintl formalism, extended by the presence of hypervalent bonding of the heavier M ‧ elements, give insight into the chemical bonding of this series of p

  11. The study of thermal and optical properties of Sn added Pb-Se-Ge chalcogenide glass

    Science.gov (United States)

    Modgil, Vivek; Kumar, Prashant; Nidhi, A. V.; Rangra, V. S.

    2014-04-01

    Compositional dependence of thermal and optical properties of Pb9Se71Ge20-xSnx (x = 8, 9,10,11,12 at. %) glass have been studied. Glass transition and crystallization kinetic has been investigated by DSC technique under non-isothermal conditions and at different heating rates. Phase separation in the material has been observed and present phases have been detected by examining the XRD of annealed bulk samples. Material possesses good glass forming ability, glass stability and high value glass transition temperature. Various optical constants such as refractive index, extinction coefficient and optical band gap have been determined by analyzing optical transmittance data in the wavelength range of 200-2500 nm.

  12. Tilting structures in inverse perovskites, M3TtO (M = Ca, Sr, Ba, Eu; Tt = Si, Ge, Sn, Pb).

    Science.gov (United States)

    Nuss, Jürgen; Mühle, Claus; Hayama, Kyouhei; Abdolazimi, Vahideh; Takagi, Hidenori

    2015-06-01

    Single-crystal X-ray diffraction experiments were performed for a series of inverse perovskites, M3TtO (M = Ca, Sr, Ba, Eu; Tt = tetrel element: Si, Ge, Sn, Pb) in the temperature range 500-50 K. For Tt = Sn, Pb, they crystallize as an 'ideal' perovskite-type structure (Pm3m, cP5); however, all of them show distinct anisotropies of the displacement ellipsoids of the M atoms at room temperature. This behavior vanishes on cooling for M = Ca, Sr, Eu, and the structures can be regarded as `ideal' cubic perovskites at 50 K. The anisotropies of the displacement ellipsoids are much more enhanced in the case of the Ba compounds. Finally, their structures undergo a phase transition at ∼ 150 K. They change from cubic to orthorhombic (Ibmm, oI20) upon cooling, with slightly tilted OBa6 octahedra, and bonding angles O-Ba-O ≃ 174° (100 K). For the larger Ba(2+) cations, the structural changes are in agreement with smaller tolerance factors (t) as defined by Goldschmidt. Similar structural behavior is observed for Ca3TtO. Smaller Tt(4-) anions (Si, Ge) introduce reduced tolerance factors. Both compounds Ca3SiO and Ca3GeO with cubic structures at 500 K, change into orthorhombic (Ibmm) at room temperature. Whereby, Ca3SiO is the only representative within the M3TtO family where three polymorphs can be found within the temperature range 500-50 K: Pm3m-Ibmm-Pbnm. They show tiny differences in the tilting of the OCa6 octahedra, expressed by O-Ca-O bond angles of 180° (500 K), ∼ 174° (295 K) and 170° (100 K). For larger M (Sr, Eu, Ba), together with smaller Tt (Si, Ge) atoms, pronounced tilting of the OM6 octahedra, and bonding angles of O-M-O ≃ 160° (295 K) are observed. They crystallize in the anti-GdFeO3 type of structure (Pbnm, oP20), and no phase transitions occur between 500 and 50 K. The observed phase transitions are all accompanied by multiple twinning, in terms of pseudo-merohedry or reticular pseudo-merohedry.

  13. Three new chalcohalides, Ba{sub 4}Ge{sub 2}PbS{sub 8}Br{sub 2}, Ba{sub 4}Ge{sub 2}PbSe{sub 8}Br{sub 2} and Ba{sub 4}Ge{sub 2}SnS{sub 8}Br{sub 2}: Syntheses, crystal structures, band gaps, and electronic structures

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zuohong; Feng, Kai; Tu, Heng; Kang, Lei [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Lin, Zheshuai [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Yao, Jiyong, E-mail: jyao@mail.ipc.ac.cn [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Wu, Yicheng [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-10-25

    Highlights: • Three new chalcohalides: Ba{sub 4}Ge{sub 2}PbS{sub 8}Br{sub 2}, Ba{sub 4}Ge{sub 2}PbSe{sub 8}Br{sub 2} and Ba{sub 4}Ge{sub 2}SnS{sub 8}Br{sub 2} have been synthesized. • The MQ{sub 5}Br octahedra and GeQ{sub 4} tetrahedra form a three-dimensional framework with Ba{sup 2+} in the channels. • Band Gaps and electronic structures of the three compounds were studied. - Abstract: Single crystals of three new chalcohalides: Ba{sub 4}Ge{sub 2}PbS{sub 8}Br{sub 2}, Ba{sub 4}Ge{sub 2}PbSe{sub 8}Br{sub 2} and Ba{sub 4}Ge{sub 2}SnS{sub 8}Br{sub 2} have been synthesized for the first time. These isostructural compounds crystallize in the orthorhombic space group Pnma. In the structure, the tetra-valent Ge atom is tetrahedrally coordinated with four Q (Q = S, Se) atoms, while the bi-valent M atom (M = Pb, Sn) is coordinated with an obviously distorted octahedron of five Q (Q = S, Se) atoms and one Br atom, showing the stereochemical activity of the ns{sup 2} lone pair electron. The MQ{sub 5}Br (M = Sn, Pb; Q = S, Se) distorted octahedra and the GeQ{sub 4} (Q = S, Se) tetrahedra are connected to each other to form a three-dimensional framework with channels occupied by Ba{sup 2+} cations. Based on UV–vis–NIR spectroscopy measurements and the electronic structure calculations, Ba{sub 4}Ge{sub 2}PbS{sub 8}Br{sub 2}, Ba{sub 4}Ge{sub 2}PbSe{sub 8}Br{sub 2} and Ba{sub 4}Ge{sub 2}SnS{sub 8}Br{sub 2} have indirect band gaps of 2.054, 1.952, and 2.066 eV respectively, which are mainly determined by the orbitals from the Ge, M and Q atoms (M = Pb, Sn; Q = S, Se)

  14. Phase separation and thermoelectric properties of the Pb{sub 0.25}Sn{sub 0.25}Ge{sub 0.5}Te compound

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, Y.; Gelbstein, Y. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva (Israel); Dariel, M.P., E-mail: dariel@bgu.ac.il [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva (Israel)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Quasi-ternary (Pb,Sn,Ge)Te compounds with Sn (>7 at%) content are single phased at elevated (>600 Degree-Sign C) temperature. Black-Right-Pointing-Pointer On cooling, the compounds undergo a discontinuous precipitation process. Black-Right-Pointing-Pointer The discontinuous precipitation gives rise to heterogeneously nucleated coupled Pb- and Ge-rich telluride lamellae. Black-Right-Pointing-Pointer After aging (>500 h at 400 Degree-Sign C), the microstructure consists of a Pb-rich matrix with spheroidized Ge-rich telluride precipitates. Black-Right-Pointing-Pointer The aged compounds display a stable thermoelectric figure of merit, ZT = 0.95. - Abstract: The Pb{sub 0.25}Sn{sub 0.25}Ge{sub 0.5}Te compound is a promising p-type thermoelectric material. It is single phased at elevated temperature and undergoes upon cooling an allotropic transformation from the cubic Ge{sub {beta}}, to the rhombohedral Ge{sub {alpha}} structure. In addition, a phase separation takes place in the course of aging treatments within the miscibility gap at lower temperature. The phase separation in this pseudo-ternary system takes place by a discontinuous precipitation process, giving rise to a heterogeneously nucleated coupled structure of Pb- and Ge-rich lamellae, with 10{sup 2} nm to 2 {mu}m wide spacing. The presence of Sn atoms in the structure tends to suppress the spinodal decomposition and is characteristic of the low Sn content compounds. The phase separation by discontinuous precipitation follows the Johnson-Mehl-Avrami kinetics. In the course of further lengthy aging treatments at 390 Degree-Sign C, the microstructure consists of spheroidized Ge-rich precipitates in a Pb-rich telluride matrix. The thermoelectric transport properties undergo significant changes in the initial stages of the phase separation process, leading to a stable and relatively elevated figure of merit, ZT = 0.95 {+-} 0.07 at 400 Degree-Sign C.

  15. Pseudomorphic GeSn/Ge (001) heterostructures

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-11-15

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

  16. Intermetallic compounds of the heaviest elements and their homologs: The electronic structure and bonding of MM', where M =Ge, Sn, Pb, and element 114, and M'=Ni, Pd, Pt, Cu, Ag, Au, Sn, Pb, and element 114

    Science.gov (United States)

    Pershina, V.; Anton, J.; Fricke, B.

    2007-10-01

    Fully relativistic (four-component) density-functional theory calculations were performed for intermetallic dimers MM', where M =Ge, Sn, Pb, and element 114, and M'=group 10 elements (Ni, Pd, and Pt) and group 11 elements (Cu, Ag, and Au). PbM and 114M, where M are group 14 elements, were also considered. The results have shown that trends in spectroscopic properties—atomization energies De, vibrational frequencies ωe, and bond lengths Re, as a function of M', are similar for compounds of Ge, Sn, Pb, and element 114, except for De of PbNi and 114Ni. They were shown to be determined by trends in the energies and space distribution of the valence ns(M ') atomic orbitals (AOs). According to the results, element 114 should form the weakest bonding with Ni and Ag, while the strongest with Pt due to the largest involvement of the 5d(Pt) AOs. In turn, trends in the spectroscopic properties of MM' as a function of M were shown to be determined by the behavior of the np1/2(M ) AOs. Overall, De of the element 114 dimers are about 1eV smaller and Re are about 0.2a.u. larger than those of the corresponding Pb compounds. Such a decrease in bonding of the element 114 dimers is caused by the large SO splitting of the 7p orbitals and a decreasing contribution of the relativistically stabilized 7p1/2(114) AO. On the basis of the calculated De for the dimers, adsorption enthalpies of element 114 on the corresponding metal surfaces were estimated: They were shown to be about 100-150kJ/mol smaller than those of Pb.

  17. Electronic structures and magnetism of Rh{sub 3}Z (Z=Al, Ga, In, Si, Ge, Sn, Pb, Sb) with DO{sub 3} structures

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.T. [School of Material Sciences and Engineering, Hebei University of Technology, Tianjin 300130 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Dai, X.F.; Wang, L.Y. [School of Material Sciences and Engineering, Hebei University of Technology, Tianjin 300130 (China); Liu, X.F. [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Wang, W.H.; Wu, G.H. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Tang, C.C. [School of Material Sciences and Engineering, Hebei University of Technology, Tianjin 300130 (China); Liu, G.D., E-mail: gdliu1978@126.com [School of Material Sciences and Engineering, Hebei University of Technology, Tianjin 300130 (China)

    2015-03-15

    We investigate the electronic structures and magnetism of Rh{sub 3}Z (Z=Al, Ga, In, Si, Ge, Sn, Pb, Sb) with a DO{sub 3} structure using the first-principle calculations. The Rh{sub 3}Z (Z=Si, Ge, Sn, Pb) alloys have been predicted to be half-metallic ferromagnets at their equilibrium lattice parameters. The half-metallicity of Rh{sub 3}Z (Z=Si, Ge, Sn, Pb) alloys can be kept in a quite large hydrostatic strain and tetragonal distortion. The magnetic properties are discussed. The Rh{sub 3}Z (Z=Si, Ge, Sn, Pb) alloys do not follow the M{sub t}=Z{sub t}-24 rule but instead of following the M{sub t}=Z{sub t}-28 rule (M{sub t} is the total magnetic moment per unit cell and Z{sub t} is the valence concentration). Moreover, all the alloys investigated in this paper have a negative formation energy, which implies that they are possible to be synthesized in reality. - Highlights: • We studied the electronic structures and magnetism of the Rh{sub 3}Z alloys. • Rh{sub 3}Z alloys are half-metallic ferromagnets at their equilibrium lattice constants. • Rh{sub 3}Z alloys retain a high spin polarization in a wide range of lattice distortions. • Rh{sub 3}Z alloys with DO{sub 3} structure follow the Slater–Pauling rule M{sub t}=Z{sub t}-28.

  18. Characteristics of Sn segregation in Ge/GeSn heterostructures

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-13

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

  19. Vibrationally high-resolved electronic spectra of MCl2 (M = C, Si, Ge, Sn, Pb) and photoelectron spectra of MCl2-

    Science.gov (United States)

    Ran, Yibin; Pang, Min; Shen, Wei; Li, Ming; He, Rongxing

    2016-10-01

    We systematically studied the vibrational-resolved electronic spectra of group IV dichlorides using the Franck-Condon approximation combined with the Duschinsky and Herzberg-Teller effects in harmonic and anharmonic frameworks (only the simulation of absorption spectra includes the anharmonicity). Calculated results showed that the band shapes of simulated spectra are in accordance with those of the corresponding experimental or theoretical ones. We found that the symmetric bend mode in progression of absorption is the most active one, whereas the main contributor in photoelectron spectra is the symmetric stretching mode. Moreover, the Duschinsky and anharmonic effects exert weak influence on the absorption spectra, except for PbCl2 molecule. The theoretical insights presented in this work are significant in understanding the photophysical properties of MCl2 (M = C, Si, Ge, Sn, Pb) and studying the Herzberg-Teller and the anharmonic effects on the absorption spectra of new dichlorides of this main group.

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

    Science.gov (United States)

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

    2015-11-01

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

  1. Electronic structure, magnetic and thermal properties of Rh{sub 2}MnZ (Z=Ge, Sn, Pb) compounds under pressure from ab-initio quasi-harmonic method

    Energy Technology Data Exchange (ETDEWEB)

    Benkhelifa, F.Z.; Lekhal, A.; Méçabih, S., E-mail: mecabihsa@yahoo.com; Abbar, B.; Bouhafs, B.

    2014-12-15

    We have investigated the electronic structure, magnetic and thermal properties of the ternary full-Heusler alloys Rh{sub 2}MnZ (Z=Ge, Sn, Pb) under pressure employing the full potential linearized augmented plane wave (FP-LAPW) plus local orbitals method based on the density functional theory (DFT), For the exchange–correlation effects we have adopted the generalized gradient approximation (GGA).Through the quasi-harmonic Debye model, we also study the thermodynamic properties of Rh{sub 2}MnZ (Z=Ge, Sn and Pb). The thermal expansion versus temperature and pressure, the thermodynamic parameters (Debye temperature and specific heat) with pressure P, and the heat capacity at various pressures and temperatures in the ranges of 0 GPa to 0.6 GPa and 0 K to 400 K have been obtained. - Highlights: • Ab-initio study of the electronic properties of Rh{sub 2}MnZ (Z=Ge, Sn, Pb). • Thermodynamic properties of Rh{sub 2}MnZ (Z=Ge, Sn and Pb) are predicted. • Pressure effect on the structural and electronic properties. • The effect of temperature and pressure on the Debye temperature.

  2. The study of bonding in pyramidanes [(Me3Si)4C4]E (E = Ge, Sn, Pb) by optical (Raman, UV-vis) spectroscopy and quantum-chemical methods

    Science.gov (United States)

    Leites, Larissa A.; Aysin, Rinat R.; Bukalov, Sergey S.; Lee, Vladimir Ya.; Sugasawa, Hakura; Sekiguchi, Akira

    2017-02-01

    The nature of the apex-base bonds in organometallics of a novel class - pyramidanes [(Me3Si)4C4]E (E = Ge, Sn, Pb) was shown to be covalent but with a high degree of polarity on the basis of the Raman data and the results of QTAIM analysis. NICS data suggest three-dimensional aromaticity of the C4E pyramid.

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

    Science.gov (United States)

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

    2014-08-15

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

  4. Optical spectra, electronic structure and aromaticity of benzannulated N-heterocyclic carbene and its analogues of the type C6H4(NR)2E: (E = Si, Ge, Sn, Pb).

    Science.gov (United States)

    Aysin, Rinat R; Bukalov, Sergey S; Leites, Larissa A; Zabula, Alexander V

    2017-02-24

    A series of benzannulated N-heterocyclic compounds containing divalent 14 group atoms, C6H4(NR)2E(II), E = C, Si, Ge, Sn, Pb, have been studied by various experimental (vibrational and UV-vis spectroscopy) and theoretical (NICS, ISE, ACID) techniques. The methods used confirm 10 π-electron delocalization (aromaticity) in these heterocycles, however, the aromaticity sequences estimated by the criteria based on different physical properties do not coincide.

  5. First-Principles Calculation of Dehydrogenating Properties of MgH2-X(X=Si, Ge, Sn, Pb) Systems%MgH2-X(X=Si,Ge,Sn,Pb)体系解氢能力的第一原理计算

    Institute of Scientific and Technical Information of China (English)

    周惦武; 刘金水; 张健; 彭平

    2006-01-01

    采用基于密度泛函理论的第一原理赝势平面波方法,研究了MgH2-X(X=Si,Ge,Sn,Pb)合金化体系的能量、几何与电子结构.负形成热的计算发现:合金化元素X在镁氢化合物(MgH2)中少量固溶时,体系相结构稳定性变差,预示着解氢能力得到改善.电子态密度(DOS)与电子密度的进一步分析发现:镁氢化合物X合金化后,X与其周围的H原子相互作用不明显,而Mg-H之间的成键作用减弱.体系Ge合金化解氢能力增强的理论计算与实验结果一致,预测Si,Sn,Pb少量固溶于MgH2能提高体系的解氢能力.

  6. Phase stabilities of pyrite-related MTCh compounds (M=Ni, Pd, Pt; T=Si, Ge, Sn, Pb; Ch=S, Se, Te): A systematic DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Bachhuber, Frederik [University of Regensburg, Institute of Inorganic Chemistry, Universitätsstr. 31, 93040 Regensburg (Germany); School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland (New Zealand); Krach, Alexander; Furtner, Andrea [University of Regensburg, Institute of Inorganic Chemistry, Universitätsstr. 31, 93040 Regensburg (Germany); Söhnel, Tilo [School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland (New Zealand); Centre for Theoretical Chemistry and Physics, The New Zealand Institute for Advanced Study, Massey University Auckland, Auckland (New Zealand); Peter, Philipp; Rothballer, Jan [University of Regensburg, Institute of Inorganic Chemistry, Universitätsstr. 31, 93040 Regensburg (Germany); Weihrich, Richard, E-mail: richard.weihrich@chemie.uni-r.de [University of Regensburg, Institute of Inorganic Chemistry, Universitätsstr. 31, 93040 Regensburg (Germany)

    2015-03-15

    Pyrite-type and related systems appear for a wide range of binary and ternary combinations of transition metals and main group elements that form Zintl type dumbbell anion units. Those representatives with 20 valence electrons exhibit an extraordinary structural flexibility and interesting properties as low-gap semiconductors or thermoelectric and electrode materials. This work is devoted to the systematic exploration of novel compounds within the class of MTCh compounds (M=Ni, Pd, Pt; T=Si, Ge, Sn, Pb; Ch=S, Se, Te) by means of density functional calculations. Their preferred structures are predicted from an extended scheme of colored pyrites and marcasites. To determine their stabilities, competing binary MT{sub 2} and MCh{sub 2} boundary phases are taken into account as well as ternary M{sub 3}T{sub 2}Ch{sub 2} and M{sub 2}T{sub 3}Ch{sub 3} systems. Recently established stability diagrams are presented to account for MTCh ordering phenomena with a focus on a not-yet-reported ordering variant of the NiAs{sub 2} type. Due to the good agreement with experimental data available for several PtTCh systems, the predictions for the residual systems are considered sufficiently accurate. - Graphical abstract: Compositional and structural stability of MTCh compounds is investigated from first principle calculations. A conceptional approach is presented to study and predict novel stable and metastable compounds and structures of low gap semiconductors with TCh dumbbell units that are isoelectronic and structurally related to pyrite (FeS{sub 2}). - Highlights: • Study of compositional stability of MTCh vs. M{sub 3}T{sub 2}Ch{sub 2} and M{sub 2}T{sub 3}Ch{sub 3} compounds. • Study of structural stability of known and novel MTCh compounds. • Prediction of novel stable and metastable structures and compounds isoelectronic to pyrite, FeS{sub 2}.

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

    Science.gov (United States)

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

    2016-11-01

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

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

    Science.gov (United States)

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

    2016-08-01

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

  9. Aromatic Character Studies on Divalent 3, 5 and 7-membered Rings C2H2M,C4H4M and C6H6M(M=C,Si,Ge,Sn and Pb)via Nucleus-independent Chemical Shifts (NICS) Calculation%通过核独立化学位移(NICS)计算研究二价三、五、七元环C2H2M,C4H4M and C6H6M(M=C,Si,Ge,Sn and Pb)的芳香族特性

    Institute of Scientific and Technical Information of China (English)

    Vessally E; Nikoorazm M; Ramazani A

    2008-01-01

    The aromatic character of divalent three, five and seven-membered rings C2H2M,C4H4 and C6H6M(M=C,Si, Ge, Sn and Pb) is investigated through magnetic and geometric criteria by Density Functional Theory (DFT) method using 6-311++G (3df,2p) basis set of the GAUSSIAN 98 program. The result of Nucleus-independent Chemical Shifts (NICS) (0.5) calculations show an aromatic character for singlet state of C2H2M,(M=C, Si, Ge, Sn and Sn) and nonaromatic character for triplet states of C2H2M (except M =Ge and Pb). NICS (0.5) calculations show nonaromatic character for the singlet state of C4H4C and antiaromatic character for C4H4M (M=Si, Ge, Sn and Pb). In contrast, NICS (0.5) calculations indicate antiaromatic character for the triplet state of C4H4C and nonaromatic character to C4H4M (M=Si, Ge, Sn and Pb). NICS (0.5) calculations show a slightly homoaromatic character for the singlet state of C6H6M and anti-aromatic character for triplet state of C6H6M.

  10. Electronic structures and magnetism in the Li{sub 2}AgSb-type Heusler alloys, Zr{sub 2}CoZ (Z=Al, Ga, In, Si, Ge, Sn, Pb, Sb): A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.T.; Cui, Y.T. [School of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400044 (China); Liu, X.F. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Liu, G.D., E-mail: gdliu1978@126.com [School of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400044 (China)

    2015-11-15

    The electronic and magnetic properties of Zr{sub 2}CoZ (Z=Al, Ga, In, Si, Ge, Sn, Pb, and Sb) alloys with a Li{sub 2}AgSb-type structure were investigated systematically using the first-principle calculations. Zr{sub 2}CoZ (Z=Al, Ga, In, Si, Ge, Sn, and Pb) alloys are predicted to be half-metallic ferromagnets at their equilibrium lattice constants. The Zr{sub 2}Co-based alloys have M{sub t} (the total magnetic moment per unit cell) and Z{sub t} (the valence concentration) values following Slater–Pauling rule of M{sub t}=Z{sub t}−18. The effects of lattice constants on the electronic and the magnetic properties are discussed in detail. Moreover, all the alloys investigated in this paper have a negative formation energy, which implies that they are thermodynamically stable. - Highlights: • We studied the electronic and magnetic properties of Zr{sub 2}CoZ alloys. • Zr{sub 2}CoZ alloys are HM ferromagnets in Li{sub 2}AgSb-type structure. • Zr{sub 2}CoZ alloys retain a high spin polarization in a wide range of lattice distortions. • Zr{sub 2}CoZ alloys follow the Slater–Pauling rule M{sub t}=Z{sub t}−18.

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

    Science.gov (United States)

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

    2017-02-01

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

  12. Epi-cleaning of Ge/GeSn heterostructures

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-28

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

  13. (Si)GeSn nanostructures for light emitters

    Science.gov (United States)

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

    2016-05-01

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

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

    Science.gov (United States)

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

    2016-06-01

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

  15. Parametrized dielectric functions of amorphous GeSn alloys

    Science.gov (United States)

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

    2015-09-01

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

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

    Science.gov (United States)

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

    2016-12-01

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

  17. First principle research of possible HM-AFM in double perovskites A2MoOsO6 and A2TcReO6 (A = Si, Ge, Sn, and Pb) with group IVA elements set on the A-site position

    Science.gov (United States)

    Fuh, Huei-Ru; Liu, Yun-Ping; Wang, Yin-Kuo

    2013-05-01

    We calculated electronic structures of double perovskite structures of A2MoOsO6 and A2TcReO6 (A = Si, Ge, Sn, and Pb) based on the density functional theory which was carried out with a full structural optimization using generalized gradient approximation and taking into account the correlation effect (GGA + U). In GGA calculation, Pb2TcReO6 shows a half-metallic antiferromagnet (HM-AFM) characteristic, whereas Sn2MoOsO6, Pb2MoOsO6, and Sn2TcReO6 are nearly HM-AFMs. With GGA + U calculation, Sn2MoOsO6 and Pb2MoOsO6 become stable HM-AFM, but Sn2TcReO6 and Pb2TcReO6 changes HM-AFM into an antiferromagnetic insulator. The p-d hybridization between B(B')d-Op and double exchange interaction is the mean reason to result in the half-metallic and compensated ferrimagnetic phase.

  18. Process modules for GeSn nanoelectronics with high Sn-contents

    Science.gov (United States)

    Schulte-Braucks, C.; Glass, S.; Hofmann, E.; Stange, D.; von den Driesch, N.; Hartmann, J. M.; Ikonic, Z.; Zhao, Q. T.; Buca, D.; Mantl, S.

    2017-02-01

    This paper systematically studies GeSn n-FETs, from individual process modules to a complete device. High-k gate stacks and NiGeSn metallic contacts for source and drain are characterized in independent experiments. To study both direct and indirect bandgap semiconductors, a range of 0-14.5 at.% Sn-content GeSn alloys are investigated. Special emphasis is placed on capacitance-voltage (C-V) characteristics and Schottky-barrier optimization. GeSn n-FET devices are presented including temperature dependent I-V characteristics. Finally, as an important step towards implementing GeSn in tunnel-FETs, negative differential resistance in Ge0.87Sn0.13 tunnel-diodes is demonstrated at cryogenic temperatures. The present work provides a base for further optimization of GeSn FETs and novel tunnel FET devices.

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

    Science.gov (United States)

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

    2014-05-05

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

  20. Epitaxial growth of strained and unstrained GeSn alloys up to 25% Sn

    Energy Technology Data Exchange (ETDEWEB)

    Oehme, Michael, E-mail: oehme@iht.uni-stuttgart.de; Kostecki, Konrad; Schmid, Marc; Oliveira, Filipe; Kasper, Erich; Schulze, Jörg

    2014-04-30

    Strained and unstrained GeSn layers on Si substrates were grown with Sn contents up to 20% and 25%, respectively. All metastable layer structures were fabricated by means of an ultra-low temperature molecular beam epitaxy process. The useful thickness of the metastable layers for a range of Sn contents, growth temperatures and two different strain values (unstrained, compressive strained) is explored. The epitaxial breakdown thickness which limits the useful thickness range decreases exponentially with increasing growth temperature and Sn concentration. - Highlights: • GeSn epitaxy • GeSn layers with Sn contents up to 25% • Limited layer thickness.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-15

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

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

    Science.gov (United States)

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

    2016-09-01

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

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

    Science.gov (United States)

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

    2014-01-08

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

  4. Singlet-triplet energy differences in divalent five membered cyclic conjugated Arduengo-type carbenes XC2HN2M (M = C, Si, Ge, Sn, and Pb; X = F, Cl, Br, and I)

    Science.gov (United States)

    Vessally, Esmail; Dehbandi, Behnam; Ahmadi, Elaheh

    2016-09-01

    Singlet-triplet energy differences in Arduengo-type carbenes XC2HN2C compared and contrasted with their sila, germa, stana and plumba analogues; at B3LYP/6-311++G** level of theory. Free Gibbs energy differences between triplet (t) and singlet (s) states (Δ G(t-s)) change in the following order: plumbylenes > stannylenes > germylenes > silylenes > carbenes. The singlet states in XC2HN2C are generally more stable when the electron withdrawing groups such as-F was used at β-position. However, the singlet states in XC2N2HM (M = Si, Ge, Sn, and Pb) are generally more stable when the withdrawing groups such as-F was placed. The puckering energy is investigated for each the singlet and triplet states. The DFT calculations found the linear correlation to size of the group 14 divalent element (M), the ∠N-M-N angle, and the Δ(LUMO-HOMO) of XC2HN2M.

  5. Process Modules for GeSn Nanoelectronics with high Sn-contents

    OpenAIRE

    Schulte-Braucks, C; Glass, S; Hofmann, E; Stange, D; Von Den Driesch, N; Hartmann, JM; Ikonic, Z; Zhao, GT; Buca, D.; Mantl, S

    2017-01-01

    This paper systematically studies GeSn n-FETs, from individual process modules to a complete device. High-k gate stacks and NiGeSn metallic contacts for source and drain are characterized in independent experiments. To study both direct and indirect bandgap semiconductors, a range of 0 at.% to 14.5 at.% Sn-content GeSn alloys are investigated. Special emphasis is placed on capacitance-voltage (C-V) characteristics and Schottky-barrier optimization. GeSn n-FET devices are presented including t...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-15

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

  7. α-PbO2-type high-pressure polymorph of GeO2

    Science.gov (United States)

    Prakapenka, Vitali B.; Dubrovinsky, Leonid S.; Shen, Guoyin; Rivers, Mark L.; Sutton, Stephen R.; Dmitriev, V.; Weber, H.-P.; Le Bihan, T.

    2003-04-01

    We have studied the high pressure polymorphism of GeO2 at pressures up to 60 GPa and temperatures to ˜1800 K in a laser-heated diamond anvil cell. We have synthesized an α-PbO2-type (space group Pbcn) phase of GeO2 and demonstrated that it is the stable post-CaCl2-type (space group Pnnm) polymorph at pressures above 44 GPa. The α-PbO2-structured GeO2, with a bulk modulus of 256(5) GPa, is denser than CaCl2 type by 1.6% at 60 GPa. Our study shows that group-IV element dioxides (SiO2, GeO2, SnO2, and PbO2) have a common sequence of high-pressure structural transformations: rutile-type⇒CaCl2-type⇒α-PbO2-type.

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

    Science.gov (United States)

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

    2012-12-03

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

  9. Phase segregation in Pb:GeSbTe chalcogenide system

    Science.gov (United States)

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

    2008-01-01

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

  10. 70 °C synthesis of high-Sn content (25%) GeSn on insulator by Sn-induced crystallization of amorphous Ge

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-02-23

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

  11. Crystal Chemistry of the New Families of Interstitial Compounds R6Mg23C (R = La, Ce, Pr, Nd, Sm, or Gd) and Ce6Mg23Z (Z = C, Si, Ge, Sn, Pb, P, As, or Sb).

    Science.gov (United States)

    Wrubl, Federico; Manfrinetti, Pietro; Pani, Marcella; Solokha, Pavlo; Saccone, Adriana

    2016-01-01

    The crystal chemical features of the new series of compounds R6Mg23C with R = La-Sm or Gd and Ce6Mg23Z with Z = C, Si, Ge, Sn, Pb, P, As, or Sb have been studied by means of single-crystal and powder X-ray diffraction techniques. All phases crystallize with the cubic Zr6Zn23Si prototype (cF120, space group Fm3̅m, Z = 4), a filled variant of the Th6Mn23 structure. While no Th6Mn23-type binary rare earth-magnesium compound is known to exist, the addition of a third element Z (only 3 atom %), located into the octahedral cavity of the Th6Mn23 cell (Wyckoff site 4a), stabilizes this structural arrangement and makes possible the formation of the ternary R6Mg23Z compounds. The results of both structural and topological analyses as well as of LMTO electronic structure calculations show that the interstitial element plays a crucial role in the stability of these phases, forming a strongly bonded [R6Z] octahedral moiety spaced by zeolite cage-like [Mg45] clusters. Considering these two building units, the crystal structure of these apparently complex intermetallics can be simplified to the NaCl-type topology. Moreover, a structural relationship between RMg3 and R6Mg23C compounds has been unveiled; the latter can be described as substitutional derivatives of the former. The geometrical distortions and the consequent symmetry reduction that accompany this transformation are explicitly described by means of the Bärnighausen formalism within group theory.

  12. Parametrized dielectric functions of amorphous GeSn alloys

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-28

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-28

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

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

    Science.gov (United States)

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

    2015-12-01

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

  16. GeSn/Si Avalanche Photodetectors on Si substrates

    Science.gov (United States)

    2016-09-16

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

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

    Science.gov (United States)

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

    2017-04-01

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

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

    Science.gov (United States)

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

    2012-02-13

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

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

    Science.gov (United States)

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

    2015-11-01

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

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

    Science.gov (United States)

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

    2015-05-01

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

  1. Sn-inserted Al-induced layer exchange for large-grained GeSn thin films on insulator

    OpenAIRE

    Toko, Kaoru; Oya, Naoki; Nakata, Mitsuki; Suemasu, Takashi

    2016-01-01

    Large-grained polycrystalline GeSn layers on glass are achieved through the layer exchange between a-Ge and Sn-doped Al layers. The thicker Sn layers, inserted below Al layers, provided the faster growth velocity, resulting in the smaller grain size of the GeSn layer. Controlling the Sn thickness (10 nm) and the growth temperature (300 °C) allowed for approximately 80% (111)-oriented GeSn layer with grains having an average size of 40 μm. The lower growth temperature led to the higher Sn cont...

  2. Franz-Keldysh effect in GeSn pin photodetectors

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-04-21

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

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

    Science.gov (United States)

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

    2016-06-01

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

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

    Science.gov (United States)

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

    2015-03-01

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

  5. Chemically Resolved Structure of the Sn/Ge(111) Surface

    Science.gov (United States)

    Lee, Tien-Lin; Warren, Samantha; Cowie, Bruce C. C.; Zegenhagen, Jörg

    2006-02-01

    The structure and chemical states of the Sn/Ge(111) surface are characterized by x-ray standing waves combined with photoemission. For the room temperature 3×3 phase two chemical components, approximately 0.4 eV apart, are observed for both Sn 3d and 4d core levels. Our model-independent, x-ray standing wave analysis shows unambiguously that the two components originate from Sn adatoms located at two different heights separated vertically by 0.23 Å, in favor of a model composed of a fluctuating Sn layer. Contrary to the most accepted scenario, the stronger Sn 3d and 4d components, which appear at the lower binding-energy sides and account for 2/3 of the Sn adatoms, are identified to be associated with the higher Sn position, manifesting their filled valence state character.

  6. Lattice Thermal Conductivity of the Binary and Ternary Group-IV Alloys Si-Sn, Ge-Sn, and Si-Ge-Sn

    Science.gov (United States)

    Khatami, S. N.; Aksamija, Z.

    2016-07-01

    Efficient thermoelectric (TE) energy conversion requires materials with low thermal conductivity and good electronic properties. Si-Ge alloys, and their nanostructures such as thin films and nanowires, have been extensively studied for TE applications; other group-IV alloys, including those containing Sn, have not been given as much attention as TEs, despite their increasing applications in other areas including optoelectronics. We study the lattice thermal conductivity of binary (Si-Sn and Ge-Sn) and ternary (Si-Ge-Sn) alloys and their thin films in the Boltzmann transport formalisms, including a full phonon dispersion and momentum-dependent boundary-roughness scattering. We show that Si-Sn alloys have the lowest conductivity (3 W /mK ) of all the bulk alloys, more than 2 times lower than Si-Ge, attributed to the larger difference in mass between the two constituents. In addition, we demonstrate that thin films offer an additional reduction in thermal conductivity, reaching around 1 W /mK in 20-nm-thick Si-Sn, Ge-Sn, and ternary Si-Ge-Sn films, which is near the conductivity of amorphous SiO2 . We conclude that group-IV alloys containing Sn have the potential for high-efficiency TE energy conversion.

  7. Raman spectral shift versus strain and composition in GeSn layers with 6%-15% Sn content

    Science.gov (United States)

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

    2017-03-01

    GeSn alloys are the subject of intense research activities as these group IV semiconductors present direct bandgap behaviors for high Sn contents. Today, the control of strain becomes an important challenge to improve GeSn devices. Strain micro-measurements are usually performed by Raman spectroscopy. However, different relationships linking the Raman spectral shifts to the built-in strain can be found in the literature. They were deduced from studies on low Sn content GeSn layers (i.e., xSn contributions of strain and chemical composition on the Ge-Ge Raman spectral shift. We have shown that the GeSn Raman-strain coefficient for high Sn contents is higher compared with that for pure Ge.

  8. Optical Characterization of Si-Based Ge1- x Sn x Alloys with Sn Compositions up to 12%

    Science.gov (United States)

    Al-Kabi, Sattar; Ghetmiri, Seyed Amir; Margetis, Joe; Du, Wei; Mosleh, Aboozar; Alher, Murtadha; Dou, Wei; Grant, Joshua M.; Sun, Greg; Soref, Richard A.; Tolle, John; Li, Baohua; Mortazavi, Mansour; Naseem, Hameed A.; Yu, Shui-Qing

    2016-04-01

    Optical properties of germanium tin (Ge1- x Sn x ) alloys have been comprehensively studied with Sn compositions from 0 (Ge) to 12%. Raman spectra of the GeSn samples with various Sn compositions were measured. The room temperature photoluminescence (PL) spectra show a gradual shift of emission peaks towards longer wavelength as Sn composition increases. Temperature dependent PL shows the PL intensity variation along with the temperature change, which reveals the indirectness or directness of the bandgap of the material. As temperature decreases, the PL intensity decreases with Sn composition less than 8%, indicating the indirect bandgap Ge1- x Sn x ; while the PL intensity increases with Sn composition higher than 10%, implying the direct bandgap Ge1- x Sn x . Moreover, the PL study of n-doped samples shows bandgap narrowing compared to the unintentionally (Boron) doped thin film with similar Sn compositions due to the doping.

  9. Influence of hydrogen surface passivation on Sn segregation, aggregation, and distribution in GeSn/Ge(001) materials

    Science.gov (United States)

    Johll, Harman; Samuel, Milla; Koo, Ruey Yi; Kang, Hway Chuan; Yeo, Yee-Chia; Tok, Eng Soon

    2015-05-01

    Plane-wave density functional theory is used to investigate the impact of hydrogen passivation of the p(2×2) reconstructed Ge1-xSnx surface on Sn segregation, aggregation, and distribution. On a clean surface, Sn preferentially segregates to the surface layer, with surface coverages of 25%, 50%, and 100% for total Sn concentrations of 2.5%, 5.0%, and 10.0%, respectively. In contrast, a hydrogen passivated surface increases interlayer migration of Sn to subsurface layers, in particular, to the third layer from the surface, and results in surface coverages of 0%, 0%, and 50% corresponding to Sn concentrations of 2.5%, 5.0%, and 10.0%, respectively. Hydrogen transfer from a Ge-capped surface to the one enriched with increasing Sn surface coverage is also an unfavorable process. The presence of hydrogen therefore reduces the surface energy by passivating the reactive dangling bonds and enhancing Sn interlayer migration to the subsurface layers. For both clean and hydrogenated surfaces, aggregation of Sn at the surface layer is also not favored. We explain these results by considering bond enthalpies and the enthalpies of hydrogenation for various surface reactions. Our results thus point to reduced Sn segregation to the surface in a Ge1-xSnx epitaxial thin film if CVD growth, using hydride precursors in the hydrogen limited growth regime, is used. This would lead to a more abrupt interface and is consistent with recent experimental observation. Hydrogenation is therefore a promising method for controlling and manipulating elemental population of Sn in a Ge1-xSnx epitaxial thin film.

  10. Interplay between relaxation and Sn segregation during thermal annealing of GeSn strained layers

    Science.gov (United States)

    Comrie, C. M.; Mtshali, C. B.; Sechogela, P. T.; Santos, N. M.; van Stiphout, K.; Loo, R.; Vandervorst, W.; Vantomme, A.

    2016-10-01

    The effect of thermal annealing on epitaxial GeSn (6.5% Sn) strained layers grown on Ge-buffered Si(100) wafers has been investigated using Rutherford backscattering spectrometry and X-ray diffraction to unambiguously determine the Sn substitutional content as well as the elastic strain in the layers. Vacuum annealing at temperatures below 400 °C for 20 min has no noticeable effect on the strain in the epitaxial layers. Once the temperature was raised above 400 °C, however, relaxation of the layer sets in and the GeSn layer has essentially completely relaxed following a 20 min anneal at 650 °C. Using Rutherford backscattering and channelling spectrometry to provide compositional information as a function of depth enables one to monitor the effect of the thermal anneal on the Sn distribution throughout the layer, and also to directly extract their substitutional fraction (i.e., their solubility in the lattice). The results obtained show that when the relaxation initially sets in both the Ge and the Sn remain firmly bound in substitutional lattice sites and it is only around 600 °C, and after substantial relaxation has taken place, that Sn is finally expelled from lattice sites and diffuses to the surface of the sample.

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

    Science.gov (United States)

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

    2015-08-01

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

  12. Study of GeSn based heterostructures: towards optimized group IV MQW LEDs

    National Research Council Canada - National Science Library

    Stange, D; von den Driesch, N; Rainko, D; Schulte-Braucks, C; Wirths, S; Mussler, G; Tiedemann, A T; Stoica, T; Hartmann, J M; Ikonic, Z; Mantl, S; Grützmacher, D; Buca, D

    2016-01-01

    .... An alternative solution using SiGeSn as barrier material is introduced, which provides appropriate band alignment for both electrons and holes resulting in efficient confinement in direct bandgap GeSn wells...

  13. Polycrystalline GeSn thin films on Si formed by alloy evaporation

    Science.gov (United States)

    Kim, Munho; Fan, Wenjuan; Seo, Jung-Hun; Cho, Namki; Liu, Shih-Chia; Geng, Dalong; Liu, Yonghao; Gong, Shaoqin; Wang, Xudong; Zhou, Weidong; Ma, Zhenqiang

    2015-06-01

    Polycrystalline GeSn thin films on Si substrates with a Sn composition up to 4.5% have been fabricated and characterized. The crystalline structure, surface morphology, and infrared (IR) absorption coefficient of the annealed GeSn thin films were carefully investigated. It was found that the GeSn thin films with a Sn composition of 4.5% annealed at 450 °C possessed a desirable polycrystalline structure according to X-ray diffraction (XRD) analyses and Raman spectroscopy analyses. In addition, the absorption coefficient of the polycrystalline GeSn thin films in the IR region was significantly better than that of the single crystalline bulk Ge.

  14. Low Temperature Deposition of High-k/Metal Gate Stacks on High-Sn Content (Si)GeSn-Alloys

    OpenAIRE

    Schulte-Braucks, C; Von Den Driesch, N; Glass, S; Tiedemann, AT; Breuer, U; Besmehn, A; Hartmann, JM; Ikonic, Z; Zhao, QT; Mantl, S; Buca, D.

    2016-01-01

    (Si)GeSn is an emerging group IV alloy system offering new exciting properties, with great potential for low power electronics due to the fundamental direct band gap and prospects as high mobility material. In this Article, we present a systematic study of HfO2/TaN high-k/metal gate stacks on (Si)GeSn ternary alloys and low temperature processes for large scale integration of Sn based alloys. Our investigations indicate that SiGeSn ternaries show enhanced thermal stability compared to GeSn bi...

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

    Directory of Open Access Journals (Sweden)

    I. S. Yu

    2011-12-01

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

  16. Raman spectral shift versus strain and composition in GeSn layers with: 6 to 15% Sn contents

    OpenAIRE

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

    2017-01-01

    GeSn alloys are the subject of intense research activities as these group IV semiconductors present direct bandgap behaviors for high Sn contents. Today, the control of strain becomes an important challenge to improve GeSn devices. Strain micro-measurements are usually performed by Raman spectroscopy. However, different relationships linking the Raman spectral shifts to the built-in strain can be found in the literature. They were deduced from studies on low Sn content GeSn layers (i.e. xSn

  17. Low Temperature Deposition of High-k/Metal Gate Stacks on High-Sn Content (Si)GeSn-Alloys.

    Science.gov (United States)

    Schulte-Braucks, C; von den Driesch, N; Glass, S; Tiedemann, A T; Breuer, U; Besmehn, A; Hartmann, J-M; Ikonic, Z; Zhao, Q T; Mantl, S; Buca, D

    2016-05-25

    (Si)GeSn is an emerging group IV alloy system offering new exciting properties, with great potential for low power electronics due to the fundamental direct band gap and prospects as high mobility material. In this Article, we present a systematic study of HfO2/TaN high-k/metal gate stacks on (Si)GeSn ternary alloys and low temperature processes for large scale integration of Sn based alloys. Our investigations indicate that SiGeSn ternaries show enhanced thermal stability compared to GeSn binaries, allowing the use of the existing Si technology. Despite the multielemental interface and large Sn content of up to 14 atom %, the HfO2/(Si)GeSn capacitors show small frequency dispersion and stretch-out. The formed TaN/HfO2/(Si)GeSn capacitors present a low leakage current of 2 × 10(-8) A/cm(2) at -1 V and a high breakdown field of ∼8 MV/cm. For large Sn content SiGeSn/GeSn direct band gap heterostructures, process temperatures below 350 °C are required for integration. We developed an atomic vapor deposition process for TaN metal gate on HfO2 high-k dielectric and validated it by resistivity as well as temperature and frequency dependent capacitance-voltage measurements of capacitors on SiGeSn and GeSn. The densities of interface traps are deduced to be in the low 10(12) cm(-2) eV(-1) range and do not depend on the Sn-concentration. The new processes developed here are compatible with (Si)GeSn integration in large scale applications.

  18. Strangeness enhancements at central rapidity in 40 A GeV/c Pb-Pb collisions

    CERN Document Server

    Antinori, F; Badalà, A; Barbera, R; Belogianni, A; Bloodworth, I J; Bombara, M; Bruno, G E; Bull, S A; Caliandro, R; Campbell, M; Carena, W; Carrer, N; Clarke, R F; Dainese, A; Di Bari, D; Di Liberto, S; Divia, R; Elia, D; Evans, D; Feofilov, G A; Fini, R A; Ganoti, P; Ghidini, B; Grella, G; Helstrup, H; Hetland, K F; Holme, A K; Jacholkowski, A; Jones, G T; Jovanovic, P; Jusko, A; Kamermans, R; Kinson, J B; Knudson, K; Kondratiev, V; Králik, I; Kravcáková, A; Kuijer, P; Lenti, V; Lietava, R; Løvhøiden, G; Manzari, V; Mazzoni, M A; Meddi, F; Michalon, A; Morando, M; Norman, P I; Palmeri, A; Pappalardo, G S; Platt, R J; Quercigh, E; Riggi, F; Röhrich, D; Romita, R; Safarík, K; Sándor, L; Schillings, E; Segato, G; Sené, M; Sené, R; Snoeys, W; Soramel, F; Spyropoulou-Stassinaki, M; Staroba, P; Turrisi, R; Tveter, T S; Urbán, J; van de Ven, P; Vande Vyvre, P; Vascotto, A; Vik, T; Villalobos Baillie, O; Vinogradov, L; Virgili, T; Votruba, M F; Vrláková, J; Závada, P

    2010-01-01

    Results are presented on neutral kaon, hyperon and antihyperon production in Pb-Pb and p-Be interactions at 40 GeV/c per nucleon. The enhancement pattern follows the same hierarchy as seen in the higher energy data - the enhancement increases with the strangeness content of the hyperons and with the centrality of collision. The centrality dependence of the Pb-Pb yields and enhancements is steeper at 40 than at 158 A GeV/c. The energy dependence of strangeness enhancements at mid-rapidity is discussed.

  19. Sn-enriched Ge/GeSn nanostructures grown by MBE on (001) GaAs and Si wafers

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-15

    Elastically stressed metastable GeSn layers with a tin molar fraction as large as 0.185 are grown on (001) Si and GaAs wafers covered with a germanium buffer layer. A set of wafers with a deviation angle in the range 0°–10° is used. It is established that the GeSn crystal undergoes monoclinic deformation with the angle β to 88° in addition to tetragonal deformation. Misorientation of the wafers surface results in increasing efficiency of the incorporation of tin adatoms into the GeSn crystal lattice. Phase separation in the solid solution upon postgrowth annealing of the structures begins long before the termination of plastic relaxation of elastic heteroepitaxial stresses. Tin released as a result of GeSn decomposition predominantly tends to be found on the surface of the sample. Manifestations of the brittle–plastic mechanism of the relaxation of stresses resulting in the occurrence of microcracks in the subsurface region of the structures under investigation are found.

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

    Science.gov (United States)

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

    2015-08-01

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

  1. $\\psi^'$ production in Pb-Pb collisions at 158 GeV/nucleon

    CERN Document Server

    Alessandro, B; Arnaldi, R; Atayan, M; Beolè, S; Boldea, V; Bordalo, P; Borges, G; Castor, J; Chaurand, B; Cheynis, B; Chiavassa, E; Cicalò, C; Comets, M P; Constantinescu, S; Cortese, P; De Falco, A; De Marco, N; Dellacasa, G; Devaux, A; Dita, S; Drapier, O; Fargeix, J; Force, P; Gallio, M; Gerschel, C; Giubellino, P; Golubeva, M B; Gonin, M; Grigorian, A A; Grossiord, J Y; Guber, F F; Guichard, A; Gulkanian, H R; Idzik, M; Jouan, D; Karavicheva, T L; Kluberg, L; Kurepin, A B; Le Bornec, Y; Lourenço, C; MacCormick, M; Marzari-Chiesa, A; Masera, M; Masoni, A; Monteno, M; Musso, A; Petiau, P; Piccotti, A; Pizzi, J R; Prino, F; Puddu, G; Quintans, C; Ramello, L; Ramos, S; Riccati, L; Romana, A; Santos, H; Saturnini, P; Scomparin, E; Serci, S; Shahoyan, R; Sitta, M; Sonderegger, P; Tarrago, X; Topilskaya, N S; Usai, G L; Vercellin, E; Villatte, L; Willis, N

    2007-01-01

    \\psi^' production is studied in Pb-Pb collisions at 158 GeV/c per nucleon incident momentum. Absolute cross-sections are measured and production rates are investigated as a function of the centrality of the collision. The results are compared with those obtained for lighter colliding systems and also for the J/\\psi meson produced under identical conditions.

  2. Growth and applications of GeSn-related group-IV semiconductor materials.

    Science.gov (United States)

    Zaima, Shigeaki; Nakatsuka, Osamu; Taoka, Noriyuki; Kurosawa, Masashi; Takeuchi, Wakana; Sakashita, Mitsuo

    2015-08-01

    We review the technology of Ge1-x Sn x -related group-IV semiconductor materials for developing Si-based nanoelectronics. Ge1-x Sn x -related materials provide novel engineering of the crystal growth, strain structure, and energy band alignment for realising various applications not only in electronics, but also in optoelectronics. We introduce our recent achievements in the crystal growth of Ge1-x Sn x -related material thin films and the studies of the electronic properties of thin films, metals/Ge1-x Sn x , and insulators/Ge1-x Sn x interfaces. We also review recent studies related to the crystal growth, energy band engineering, and device applications of Ge1-x Sn x -related materials, as well as the reported performances of electronic devices using Ge1-x Sn x related materials.

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

    Science.gov (United States)

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

    2016-09-01

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

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

    Science.gov (United States)

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

    2015-03-01

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

  5. Giant Seebeck effect in Ge-doped SnSe

    Science.gov (United States)

    Gharsallah, M.; Serrano-Sánchez, F.; Nemes, N. M.; Mompeán, F. J.; Martínez, J. L.; Fernández-Díaz, M. T.; Elhalouani, F.; Alonso, J. A.

    2016-06-01

    Thermoelectric materials may contribute in the near future as new alternative sources of sustainable energy. Unprecedented thermoelectric properties in p-type SnSe single crystals have been recently reported, accompanied by extremely low thermal conductivity in polycrystalline samples. In order to enhance thermoelectric efficiency through proper tuning of this material we report a full structural characterization and evaluation of the thermoelectric properties of novel Ge-doped SnSe prepared by a straightforward arc-melting method, which yields nanostructured polycrystalline samples. Ge does not dope the system in the sense of donating carriers, yet the electrical properties show a semiconductor behavior with resistivity values higher than that of the parent compound, as a consequence of nanostructuration, whereas the Seebeck coefficient is higher and thermal conductivity lower, favorable to a better ZT figure of merit.

  6. Buffer-Free GeSn and SiGeSn Growth on Si Substrate Using In Situ SnD4 Gas Mixing

    Science.gov (United States)

    Mosleh, Aboozar; Alher, Murtadha; Cousar, Larry C.; Du, Wei; Ghetmiri, Seyed Amir; Al-Kabi, Sattar; Dou, Wei; Grant, Perry C.; Sun, Greg; Soref, Richard A.; Li, Baohua; Naseem, Hameed A.; Yu, Shui-Qing

    2016-04-01

    Buffer-free GeSn and SiGeSn films have been deposited on Si via a cold-wall, ultra-high vacuum chemical vapor deposition reactor using in situ gas mixing of deuterated stannane, silane and germane. Material characterization of the films using x-ray diffraction and transmission electron microscopy shows crystalline growth with an array of misfit dislocation formed at the Si substrate interface. Energy dispersive x-ray maps attained from the samples show uniform incorporation of the elements. The Z-contrast map of the high-angle annular dark-field of the film cross section shows uniform incorporation along the growth as well. Optical characterization of the GeSn films through photoluminescence technique shows reduction in the bandgap edge of the materials.

  7. Formation of GeSn alloy on Si(100) by low-temperature molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Talochkin, A. B., E-mail: tal@isp.nsc.ru [A. V. Rzhanov Institute of Semiconductor Physics, Lavrentyev Avenue 13, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Mashanov, V. I. [A. V. Rzhanov Institute of Semiconductor Physics, Lavrentyev Avenue 13, Novosibirsk 630090 (Russian Federation)

    2014-12-29

    GeSn alloys grown on Si(100) by the low-temperature (100 °C) molecular beam epitaxy are studied using scanning tunneling microscopy and Raman spectroscopy. It is found that the effect of Sn as a surfactant modifies substantially the low-temperature growth mechanism of Ge on Si. Instead of the formation of small Ge islands surrounded by amorphous Ge, in the presence of Sn, the growth of pure Ge islands appears via the Stranski-Krastanov growth mode, and a partially relaxed Ge{sub 1−x}Sn{sub x} alloy layer with the high Sn-fraction up to 40 at. % is formed in the area between them. It is shown that the observed growth mode induced by high surface mobility of Sn and the large strain of the pseudomorphic state of Ge to Si ensures the minimum elastic-strain energy of the structure.

  8. Pb-free Sn-Ag-Cu ternary eutectic solder

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, I.E.; Yost, F.G.; Smith, J.F.; Miller, C.M.; Terpstra, R.L.

    1996-06-18

    A Pb-free solder includes a ternary eutectic composition consisting essentially of about 93.6 weight % Sn-about 4.7 weight % Ag-about 1.7 weight % Cu having a eutectic melting temperature of about 217 C and variants of the ternary composition wherein the relative concentrations of Sn, Ag, and Cu deviate from the ternary eutectic composition to provide a controlled melting temperature range (liquid-solid ``mushy`` zone) relative to the eutectic melting temperature (e.g. up to 15 C above the eutectic melting temperature). 5 figs.

  9. GeSn-on-insulator substrate formed by direct wafer bonding

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Dian; Wang, Wei; Gong, Xiao, E-mail: elegong@nus.edu.sg, E-mail: yeo@ieee.org; Yeo, Yee-Chia, E-mail: elegong@nus.edu.sg, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Lee, Kwang Hong; Wang, Bing [Low Energy Electronic Systems (LEES), Singapore MIT Alliance for Research and Technology (SMART), 1 CREATE Way, #10-01 CREATE Tower, Singapore 138602 (Singapore); Bao, Shuyu [Low Energy Electronic Systems (LEES), Singapore MIT Alliance for Research and Technology (SMART), 1 CREATE Way, #10-01 CREATE Tower, Singapore 138602 (Singapore); School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Tan, Chuan Seng [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2016-07-11

    GeSn-on-insulator (GeSnOI) on Silicon (Si) substrate was realized using direct wafer bonding technique. This process involves the growth of Ge{sub 1-x}Sn{sub x} layer on a first Si (001) substrate (donor wafer) followed by the deposition of SiO{sub 2} on Ge{sub 1-x}Sn{sub x}, the bonding of the donor wafer to a second Si (001) substrate (handle wafer), and removal of the Si donor wafer. The GeSnOI material quality is investigated using high-resolution transmission electron microscopy, high-resolution X-ray diffraction (HRXRD), atomic-force microscopy, Raman spectroscopy, and spectroscopic ellipsometry. The Ge{sub 1-x}Sn{sub x} layer on GeSnOI substrate has a surface roughness of 1.90 nm, which is higher than that of the original Ge{sub 1-x}Sn{sub x} epilayer before transfer (surface roughness is 0.528 nm). The compressive strain of the Ge{sub 1-x}Sn{sub x} film in the GeSnOI is as low as 0.10% as confirmed using HRXRD and Raman spectroscopy.

  10. Long-range correlations in PbPb collisions at 158 a *GeV

    CERN Document Server

    Alt, C; Baatar, B; Barna, D; Bartke, J; Betev, L; Bialkowska, H; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Brun, R; Buncic, P; Cerny, V; Christakoglou, P; Chvala, O; Cramer, J G; Csato, P; Darmenov, N; Dimitrov, A; Dinkelaker, P; Eckardt, V; Farantatos, G; Flierl, D; Fodor, Z; Foka, P; Freund, P; Friese, V; Gal, J; Gazdzicki, M; Georgopoulos, G; Gladysz, E; Grebieszkow, K; Hegyi, S; Hohne, C; Kadija, K; Karev, A; Kliemant, M; Kniege, S; Kolesnikov, V I; Kollegger, T; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; van Leeuwen, M; Levai, P; Litov, L; Lungwitz, B; Makariev, M; Malakhov, A I; Mateev, M; Mayes, B W; Melkumov, G L; Meurer, C; Mischke, A; Mitrovski, M; Molnar, J; Mrowczynski, S; Palla, G; Panagiotou, A D; Panayotov, D; Petridis, A; Pikna, M; Pinsky, L; Puhlhofer, F; Renfordt, R; Richard, A; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Seyboth, P; Sikler, F; Sitar, B; Skrzypczak, E; Stefanek, G; Stock, R; Strobele, H; Susa, T; Szentpetery, I; Sziklai, J; Trubnikov, V; Varga, D; Vassiliou, M; Veres, G l; Vesztergombi, G; Vranie, D; Wetzler, A; Wlodarczyk, Z; Yoo, l K; Zaranek, J; Zimanyi, J; Feofilov, G; Kolevatov, R; Kondratiev, V; Naumenko, P; Vechernin, V

    2005-01-01

    We present the 1st results of the event-by-event study of long-range correlations between event mean Pt and charged particle multiplicity using NA49 experimental data in two separated rapidity intervals in 158 A *Ge V Pb Pb collisions at the CERN SPS. Noticeable long range correlations are found. The most striking feature is the negative Prn correlation observed for the central PbPb collisions. Results are compared to the predictions of the HIJING event generator and of the String Fusion Model favoring a string fusion hypothesis.

  11. Giant piezoelectricity of monolayer group IV monochalcogenides: SnSe, SnS, GeSe, and GeS

    Energy Technology Data Exchange (ETDEWEB)

    Fei, Ruixiang; Yang, Li, E-mail: lyang@physics.wustl.edu [Department of Physics, Washington University, St. Louis, Missouri 63130 (United States); Li, Wenbin [Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Li, Ju [Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-10-26

    We predict enormous, anisotropic piezoelectric effects in intrinsic monolayer group IV monochalcogenides (MX, M=Sn or Ge, X=Se or S), including SnSe, SnS, GeSe, and GeS. Using first-principle simulations based on the modern theory of polarization, we find that their piezoelectric coefficients are about one to two orders of magnitude larger than those of other 2D materials, such as MoS{sub 2} and GaSe, and bulk quartz and AlN which are widely used in industry. This enhancement is a result of the unique “puckered” C{sub 2v} symmetry and electronic structure of monolayer group IV monochalcogenides. Given the achieved experimental advances in the fabrication of monolayers, their flexible character, and ability to withstand enormous strain, these 2D structures with giant piezoelectric effects may be promising for a broad range of applications such as nano-sized sensors, piezotronics, and energy harvesting in portable electronic devices.

  12. $\\Xi$ and $\\overline{\\Xi}$ production in 158 GeV/nucleon Pb + Pb collisions

    CERN Document Server

    Appelshauser, H.; Bailey, S.J.; Barna, D.; Barnby, L.S.; Bartke, J.; Barton, R.A.; Bialkowska, H.; Billmeier, A.; Blyth, C.O.; Bock, R.; Bormann, C.; Brady, F.P.; Brockmann, R.; Brun, R.; Buncic, P.; Caines, H.L.; Carr, L.D.; Cebra, D.A.; Cooper, G.E.; Cramer, J.G.; Cristinziani, M.; Csato, P.; Dunn, J.; Eckardt, V.; Eckhardt, F.; Ferguson, M.I.; Fischer, H.G.; Flierl, D.; Fodor, Z.; Foka, P.; Freund, P.; Friese, V.; Fuchs, M.; Gabler, F.; Geist, Walter M.; Gal, J.; Gazdzicki, M.; Gladysz, E.; Grebieszkow, J.; Gunther, J.; Harris, J.W.; Hegyi, S.; Henkel, T.; Hill, L.A.; Hummler, H.; Igo, G.; Irmscher, D.; Jacobs, P.; Jones, P.G.; Kadija, K.; Kolesnikov, V.I.; Konashenok, A.; Kowalski, M.; Lasiuk, B.; Levai, P.; Liu, F.; Malakhov, A.I.; Margetis, S.; Markert, C.; Melkumov, G.L.; Mock, A.; Molnar, J.; Nelson, John M.; Oldenburg, M.; Odyniec, G.; Palla, G.; Panagiotou, A.D.; Petridis, A.; Piper, A.; Porter, R.J.; Poskanzer, Arthur M.; Prindle, D.J.; Puhlhofer, F.; Rauch, W.; Reid, J.G.; Renfordt, R.; Retyk, W.; Ritter, H.G.; Rohrich, D.; Roland, C.; Roland, G.; Rudolph, H.; Rybicki, A.; Sandoval, A.; Sann, H.; Semenov, A.Yu.; Schafer, E.; Schmischke, D.; Schmitz, N.; Schonfelder, S.; Seyboth, P.; Seyerlein, J.; Sikler, F.; Skrzypczak, E.; Snellings, R.; Squier, G.T.A.; Stock, R.; Strobele, H.; Struck, C.; Susa, T.; Szentpetery, I.; Sziklai, J.; Toy, M.; Trainor, T.A.; Trentalange, S.; Ullrich, T.; Vassiliou, M.; Veres, G.; Vesztergombi, G.; Vranic, D.; Wang, F.; Weerasundara, D.D.; Wenig, S.; Whitten, C.; Wienold, T.; Wood, L.; Xu, N.; Yates, T.A.; Zimanyi, J.; Zhu, X.Z.; Zybert, R.

    1998-01-01

    We report measurements of Xi and Xi-bar hyperon absolute yields as a function of rapidity in 158 GeV/c Pb+Pb collisions. At midrapidity, dN/dy = 2.29 +/- 0.12 for Xi, and 0.52 +/- 0.05 for Xi-bar, leading to the ratio of Xi-bar/Xi = 0.23 +/- 0.03. Inverse slope parameters fitted to the measured transverse mass spectra are of the order of 300 MeV near mid-rapidity. The estimated total yield of Xi particles in Pb+Pb central interactions amounts to 7.4 +/- 1.0 per collision. Comparison to Xi production in properly scaled p+p reactions at the same energy reveals a dramatic enhancement (about one order of magnitude) of Xi production in Pb+Pb central collisions over elementary hadron interactions.

  13. Strangelet Search in Pb-Pb Interactions at 158 GeV /c per Nucleon

    Science.gov (United States)

    Appelquist, G.; Baglin, C.; Beringer, J.; Bohm, C.; Borer, K.; Bussière, A.; Dittus, F.; Elsener, K.; Frei, D.; Gorodetzky, Ph.; Guillaud, J. P.; Hugentobler, E.; Klingenberg, R.; Lindén, T.; Lohmann, K. D.; Moser, U.; Pal, T.; Pretzl, K.; Schacher, J.; Selldén, B.; Stoffel, F.; Tuominiemi, J.; Zhang, Q. P.

    1996-05-01

    The NA52 experiment searches for long-lived massive strange quark matter particles, so-called strangelets, produced in Pb-Pb collisions at a beam momentum of plab = 158 A GeV/c. Upper limits for the production of strangelets at zero degree production angle covering a mass to charge ratio up to 120 GeV/c2 and lifetimes tlab>~1.2 μs are given. The data presented here were taken during the 1994 lead beam running period at CERN.

  14. Directed and Elliptic Flow in 158 GeV/Nucleon Pb + Pb Collisions

    CERN Document Server

    Appelshäuser, H; Bailey, S J; Barnby, L S; Bartke, J; Barton, R A; Bialkowska, H; Blyth, C O; Bock, R; Bormann, C; Brady, F P; Brockmann, R; Buncic, N; Buncic, P; Caines, H L; Cebra, D; Cooper, G E; Cramer, J G; Csató, P; Dunn, J; Eckardt, V; Eckardt, F; Ferguson, M I; Fischer, H G; Flier, D; Fodor, Z; Foka, P; Freund, P; Friese, V; Fuchs, M; Gabler, F; Gál, J; Gazdzicki, M; Gladysz-Dziadus, E; Grebieszkow, J; Günther, J; Harris, J W; Hegyi, S; Henkel, T; Hill, L A; Huang, I; Hümmler, H; Igo, G; Irmscher, D; Jacobs, P; Jones, P G; Kadija, K; Kolesnikov, V I; Kowalski, M; Lasiuk, B; Lévai, Peter; Malakhov, A I; Margetis, S; Markert, C; Melkumov, G L; Mock, A; Molnár, J; Nelson, J M; Odyniec, Grazyna Janina; Pálla, G; Panagiotou, A D; Petridis, A; Piper, A; Porter, R J; Poskanzer, A M; Poziombka, S; Prindle, D J; Pühlhofer, F; Rauch, W; Reid, J G; Rendfort, R; Retyk, W; Ritter, H G; Röhrich, D; Roland, C; Roland, G; Rudolph, H; Rybicki, A; Sandoval, A; Sann, H; Semenov, A Yu; Schäfer, E; Scjmischke, D; Schmitz, N; Schönfelder, S; Seyboth, P; Seyerlein, J; Siklér, F; Skrzypczak, E; Squier, G T A; Stock, R; Ströbele, H; Szentpétery, I; Sziklay, J; Toy, M; Trainor, T A; Trentalage, S; Ullrich, T; Vassiliou, M; Veztergombi, G; Voloshin, S; Vranic, D; Wang, F; Weerasundara, D D; Wenig, S; Whitten, C; Wienold, T; Wood, L; Yates, T A; Zimányi, J; Zybert, R

    1998-01-01

    The directed and elliptic flow of protons and charged pions has been observed from the semi-central collisions of a 158 GeV/nucleon Pb beam with a Pb target. The rapidity and transverse momentum dependence of the flow has been measured. The directed flow of the pions is opposite to that of the protons but both exhibit negative flow at low pt. The elliptic flow of both is fairly independent of rapidity but rises with pt.

  15. Multifractal moments in heavy ion Pb-Pb collisions at 158 A GeV

    Energy Technology Data Exchange (ETDEWEB)

    Dutt, Sunil [Department of Physics, Govt. College for Women GandhiNagar, Jammu - J& K (India)

    2016-05-06

    In present work, we use the method of scaled factorial moments to search for intermittent behavior in Pb-Pb interactions at 158 A GeV. The analysis is done on photon distributions obtained using preshower photon multiplicity detector. Scaled factorial moments are used to study short range fluctuations in pseudorapidity distributions of photons. Scaled factorial moments are calculated using horizontal corrected and vertical analysis. The results are compared with simulation analysis using VENUS event generator.

  16. Antinuclei production in Pb + Pb collisions at 158 A GeV/ c

    Science.gov (United States)

    Appelquist, G.; Baglin, C.; Beringer, J.; Bohm, C.; Borer, K.; Bussière, A.; Dittus, F.; Elsener, K.; Frei, D.; Gorodetzky, Ph.; Guillaud, J. P.; Hugentobler, E.; Klingenberg, R.; Linden, T.; Lohmann, K. D.; Moser, U.; Pal, T.; Pretzl, K.; Schacher, J.; Selldén, B.; Stoffel, F.; Tuominiemi, J.; Zhang, Q. P.; Newmass (NA52) Collaboration

    1996-02-01

    We investigate antinuclei production in Pb + Pb interactions at 158 GeV/ c per nucleon at zero degree production angle. We quote invariant differential production cross sections for antiprotons and antideuterons. The corresponding antideuteron to antiproton ratio at midrapidity is 4.2 · 10 -4. One antihelium-3 nucleus was observed. The results are discussed in the framework of a simple coalescence model.

  17. Effect of Cerium on Gas Evolution Behavior of Pb-Ca-Sn Alloy

    Institute of Scientific and Technical Information of China (English)

    Lin Guanfa; Zhou Genshu; Li Dangguo; Zheng Maosheng

    2006-01-01

    The effect of Ce on the behavior of gas evolution on Pb-Ca-Sn alloy in 4.5 mol·L-1 H2SO4 was investigated using cyclic voltammetry (CV), cathodic polarization curves and AC impedance (EIS).Cyclic voltammetry experiments show that the current of oxygen evolution on Pb-Ca-Sn-Ce electrode is lower than that of Pb-Ca-Sn electrode in the same anodic voltage.Moreover, the oxygen evolution potential on the former electrode is greater than that on the latter, and this means that Ce can increase the potential of oxygen evolution on Pb-Ca-Sn alloy.The AC impedance experiments show that Ce can also enhance the resistance of hydrogen evolution on Pb-Ca-Sn electrode, i.e., Ce can inhibit the hydrogen evolution on Pb-Ca-Sn electrode.The reason why Ce decreases the volume of hydrogen evolution on Pb-Ca-Sn alloy is that Ce increases the resistance of absorbing step of hydrogen evolution reaction.All the experimental results indicate that Pb-Ca-Sn-Ce alloy can rapidly decrease the oxygen and hydrogen evolution on Pb-Ca-Sn-Ce alloy.It is concluded that Pb-Ca-Sn-Ce alloy can promote the maintenance-free property of lead acid battery, and can serve as the candidate of the grid material for maintenance-free lead acid battery.

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-01

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

  20. SiGeSn growth studies using reduced pressure chemical vapor deposition towards optoelectronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Wirths, S., E-mail: s.wirths@fz-juelich.de [Peter Grünberg Institute (PGI 9-IT) and JARA-FIT, Forschungszentrum Juelich, 52425 (Germany); Buca, D. [Peter Grünberg Institute (PGI 9-IT) and JARA-FIT, Forschungszentrum Juelich, 52425 (Germany); Ikonic, Z.; Harrison, P. [Institute of Microwaves and Photonics, School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Tiedemann, A.T.; Holländer, B.; Stoica, T.; Mussler, G. [Peter Grünberg Institute (PGI 9-IT) and JARA-FIT, Forschungszentrum Juelich, 52425 (Germany); Breuer, U. [Central Institute for Engineering, Electronics and Analytics (ZEA-3), Forschungszentrum Juelich, 52425 (Germany); Hartmann, J.M. [CEA, LETI, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble (France); Grützmacher, D.; Mantl, S. [Peter Grünberg Institute (PGI 9-IT) and JARA-FIT, Forschungszentrum Juelich, 52425 (Germany)

    2014-04-30

    In this contribution, we propose a laser concept based on a double heterostructure consisting of tensile strained Ge as the active medium and SiGeSn ternaries as cladding layers. Electronic band-structure calculations were used to determine the Si and Sn concentrations yielding a type I heterostructure with appropriate band-offsets (50 meV) between strained Ge and SiGeSn. Reduced pressure chemical vapor deposition system was employed to study the laser structure growth. Detailed analyses regarding layer composition, crystal quality, surface morphology and elastic strain are presented. A strong temperature dependence of the Si and Sn incorporation has been obtained, ranging from 4 to 19 at.% Si and from 4 to 12 at.% Sn (growth temperatures between 350 °C and 475 °C). The high single crystalline quality and low surface roughness of 0.5–0.75 nm demonstrate that our layers are suitable for heterostructure laser fabrication. - Highlights: • Sn based group IV materials for photonics • Bandstructure calculations of SiGeSn/strained Ge double heterostructures. • Si and Sn concentrations in SiGeSn layers between 4 and 19 at.% and 4 and 11 at.%, respectively. • Growth of SiGeSn layers with high crystalline quality for optoelectronic applications.

  1. GeSn p-i-n waveguide photodetectors on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Yu-Hsiang; Chang, Guo-En, E-mail: imegec@ccu.edu.tw [Department of Mechanical Engineering and Advanced Institute of Manufacturing with High-tech Innovations, National Chung Cheng University, Chia-Yi County 62102, Taiwan (China); Cheng, H. H. [Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China); Mashanov, Vladimir I. [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Lavrentjeva 13, Novosibirsk 630090 (Russian Federation)

    2014-12-08

    We report an investigation on GeSn p-i-n waveguide photodetectors grown on a Ge-buffered Si wafer. In comparison with a reference Ge detector, the GeSn detector shows an enhanced responsivity in the measured energy range, mainly attributed to the smaller bandgap caused by Sn-alloying. Analysis of the quantum efficiency indicates that increasing the Sn content in the active layers can significantly shorten the required device length to achieve the maximum efficiency. The present investigation demonstrates the planar photodetectors desired for monolithic integration with electronic devices.

  2. Preliminary results from NA52 strangelet search in Pb-Pb at 160 GeV/nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Appelquist, G.; Bohm, C. [Stockholm Univ. (Sweden). Dept. of Physics; Baglin, C.; Bussiere, A. [Grenoble-1 Univ., 74 - Annecy (France). Lab. de Physique des Particules Elementaires; Beringer, J.; Borer, K.; Dittus, F.; Frei, D. [Bern Univ. (Switzerland). Lab. fuer Hochenergiephysik; Elsener, K. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Gorodetzky, Ph. [Centre National de la Recherche Scientifique (CNRS), 67 - Strasbourg (France)] [and others

    1995-12-31

    Strangelet search in Pb-Pb interaction at 160 GeV/c per nucleon is reported on. Preliminary analysis shows the ability of NA52 to reach sensitivity down to 3.10{sup -9} strangelet/interaction. (author)

  3. Enhancement of central $\\Lambda$, $\\Xi$ and $\\Omega$ yields in Pb-Pb collisions at 158 A GeV/c

    CERN Document Server

    Andersen, E; Armenise, N; Bakke, H; Bán, J; Barberis, D; Beker, H; Beusch, Werner; Bloodworth, Ian J; Böhm, J; Caliandro, R; Campbell, M; Cantatore, E; Carrer, N; Catanesi, M G; Chesi, Enrico Guido; Dameri, M; Darbo, G; Diaczek, A; Di Bari, D; Di Liberto, S; Earl, B C; Elia, D; Evans, D; Fanebust, K; Fini, R A; Fontaine, J C; Ftácnik, J; Ghidini, B; Grella, G; Guida, M; Heijne, Erik H M; Helstrup, H; Holme, A K; Huss, D; Jacholkowski, A; Jones, G; Jovanovic, P; Jusko, A; Kachanov, V A; Kachelhoffer, T; Kinson, J B; Kirk, A; Klempt, W; Knudsen, H; Knudson, K P; Králik, I; Lassalle, J C; Lenti, V; Lietava, R; Loconsole, R A; Løvhøiden, G; Lupták, M; Mack, V; Manzari, V; Martinengo, P; Mazzoni, M A; Meddi, F; Michalon, A; Michalon-Mentzer, M E; Middelkamp, P; Morando, M; Muciaccia, M T; Nappi, E; Navach, F; Norman, P I; Osculati, B; Pastircák, B; Pellegrini, F; Píska, K; Posa, F; Quercigh, Emanuele; Ricci, R A; Romano, G; Rosa, G; Rossi, L; Rotscheidt, Herbert; Safarík, K; Saladino, S; Salvo, C; Sándor, L; Scognetti, T; Segato, G F; Sené, M; Sené, R; Simone, S; Singovsky, A V; Snoeys, W; Staroba, P; Szafran, S; Thompson, M; Thorsteinsen, T F; Tomasicchio, G; Torrieri, G D; Tveter, T S; Urbán, J; Vasileiadis, G; Venables, M; Villalobos Baillie, O; Virgili, T; Volte, A; Votruba, M F; Závada, P

    1998-01-01

    $\\Lambda$, $\\Xi$ and $\\Omega$ yields and transverse mass spectra have been measured at central rapidity in Pb-Pb and p-Pb collisions at 158~A~GeV/$c$. The yields in Pb-Pb interactions are presente d as a function of the collision centrality and compared with those obtained from p-Pb collisions. Strangeness enhancement is observed which increases with centrality and with the strangeness co ntent of the hyperon.

  4. Phase equilibria and liquid phase epitaxy growth of PbSnSeTe lattice matched to PbSe

    Science.gov (United States)

    Mccann, Patrick J.; Fonstad, Clifton G.; Fuchs, Jacob; Feit, Ze'ev

    1987-01-01

    The necessary phase diagram data for growing lattice-matched layers of PbSnSeTe on PbSe are presented. Solid compounds of Pb(1-x)Sn(x)Se(1-y)Te(y) lattice-matched to PbSe were grown from liquid melts consisting of (Pb/1-x/Sn/x/)(1-z)(Se/1-y/Te/y/)(z); phase equilibria data were determined together with liquidus data for values of x(liquid) from 0 to 40 percent and y(liquid) from 0 to 40 percent for temperatures between 450 and 540 C. It was found that relatively large amounts of Te must be added to the melt to achieve lattice matching because of its low segregation coefficient relative to Se. A significant lattice-pulling effect was discovered for the 5-percent Sn case, and a similar effect is expected for the 10- and 20-percent Sn cases.

  5. Phase transformation in Pb:GeSbTe chalcogenide films

    Science.gov (United States)

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

    2008-11-01

    A comprehensive analysis on the amorphous to crystalline phase transformation in Pb:GeSbTe chalcogenide alloy has been discussed. The structure identified with X-ray measurements has been discussed in relation to thermal analysis carried out on bulk samples. Optical constants have been calculated in the 350 to 800 nm wavelength range, using Fresnel's equation. The effect of Pb substitution on the optical contrast in terms of change in reflectivity and optical parameters (viz. refractive index, extinction coefficient) has been discussed. Marginal decrease in the optical contrast has been observed with a small increase in Pb content, which is effective to maintain the sufficient signal to noise ratio for optical phase-change storage.

  6. Sn migration control at high temperature due to high deposition speed for forming high-quality GeSn layer

    Science.gov (United States)

    Taoka, Noriyuki; Capellini, Giovanni; von den Driesch, Nils; Buca, Dan; Zaumseil, Peter; Schubert, Markus Andreas; Klesse, Wolfgang Matthias; Montanari, Michele; Schroeder, Thomas

    2016-03-01

    A key factor for controlling Sn migration during GeSn deposition at a high temperature of 400 °C was investigated. Calculated results with a simple model for the Sn migration and experimental results clarified that low-deposition-speed (vd) deposition with vd’s of 0.68 and 2.8 nm/min induces significant Sn precipitation, whereas high-deposition-speed (vd = 13 nm/min) deposition leads to high crystallinity and good photoluminescence spectrum of the GeSn layer. These results indicate that vd is a key parameter, and that control of Sn migration at a high temperature is possible. These results are of great relevance for the application of high-quality Sn-based alloys in future optoelectronics devices.

  7. Pulse number controlled laser annealing for GeSn on insulator structure with high substitutional Sn concentration

    Science.gov (United States)

    Moto, Kenta; Matsumura, Ryo; Sadoh, Taizoh; Ikenoue, Hiroshi; Miyao, Masanobu

    2016-06-01

    Crystalline GeSn-on-insulator structures with high Sn concentration (>8%), which exceeds thermal equilibrium solid-solubility (˜2%) of Sn in Ge, are essential to achieve high-speed thin film transistors and high-efficiency optical devices. We investigate non-thermal equilibrium growth of Ge1-xSnx (0 ≤ x ≤ 0.2) on quartz substrates by using pulsed laser annealing (PLA). The window of laser fluence enabling complete crystallization without film ablation is drastically expanded (˜5 times) by Sn doping above 5% into Ge. Substitutional Sn concentration in grown layers is found to be increased with decreasing irradiation pulse number. This phenomenon can be explained on the basis of significant thermal non-equilibrium growth achieved by higher cooling rate after PLA with a lower pulse number. As a result, GeSn crystals with substitutional Sn concentration of ˜12% are realized at pulse irradiation of single shot for the samples with the initial Sn concentration of 15%. Raman spectroscopy and electron microscopy measurements reveal the high quality of the grown layer. This technique will be useful to fabricate high-speed thin film transistors and high-efficiency optical devices on insulating substrates.

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

    Science.gov (United States)

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

    2014-09-01

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

  9. Photocatalytic Degradation of Isopropanol Over PbSnO3Nanostructures Under Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Chen Di

    2009-01-01

    Full Text Available Abstract Nanostructured PbSnO3photocatalysts with particulate and tubular morphologies have been synthesized from a simple hydrothermal process. As-prepared samples were characterized by X-ray diffraction, Brunauer–Emmet–Teller surface area, transmission electron microscopy, and diffraction spectroscopy. The photoactivities of the PbSnO3nanostructures for isopropanol (IPA degradation under visible light irradiation were investigated systematically, and the results revealed that these nanostructures show much higher photocatalytic properties than bulk PbSnO3material. The possible growth mechanism of tubular PbSnO3catalyst was also investigated briefly.

  10. Optical and X-ray photoelectron spectroscopy of PbGeO3 and Pb5Ge3O11 single crystals

    Indian Academy of Sciences (India)

    S C Sabharwal; S N Jha; Sangeeta

    2010-08-01

    Pb5Ge3O11 crystals are found to exhibit pale yellow colouration while PbGeO3 are colourless. X-ray photoelectron spectroscopy (XPS) measurements show lead deficiency in both the crystals. The results also reveal a stronger ionic character for PbGeO3 as compared to Pb5Ge3O11 crystal. The binding energy of Ge3 core level in the case of Pb5Ge3O11 crystal is found to be smaller than the binding energy of germanium oxide, thereby indicating the incomplete oxidation of Ge ions in the crystal lattice. On gamma ray irradiation, the transmission of both the crystals is observed to deteriorate uniformly over the entire wavelength range, which has been attributed to the oxidation of some of the lattice Pb ions. On gamma irradiation the changes observed in O1 core level energies for both the crystals are seen to be consistent with the changes noted in the Pb47/2 and Ge3 spectra. Interestingly, the results reveal oxidation of surface Ge atoms with atmospheric oxygen under gamma irradiation.

  11. Investigation of Sn surface segregation during GeSn epitaxial growth by Auger electron spectroscopy and energy dispersive x-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tsukamoto, Takahiro; Suda, Yoshiyuki [Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Hirose, Nobumitsu; Kasamatsu, Akifumi; Mimura, Takashi; Matsui, Toshiaki [National Institute of Information and Communications Technology, 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795 (Japan)

    2015-02-02

    The mechanism of Sn surface segregation during the epitaxial growth of GeSn on Si (001) substrates was investigated by Auger electron spectroscopy and energy dispersive X-ray spectroscopy. Sn surface segregation depends on the growth temperature and Sn content of GeSn layers. During Sn surface segregation, Sn-rich nanoparticles form and move on the surface during the deposition, which results in a rough surface owing to facet formation. The Sn-rich nanoparticles moving on the surface during the deposition absorb Sn from the periphery and yield a lower Sn content, not on the surface but within the layer, because the Sn surface segregation and the GeSn deposition occur simultaneously. Sn surface segregation can occur at a lower temperature during the deposition compared with that during postannealing. This suggests that the Sn surface segregation during the deposition is strongly promoted by the migration of deposited Ge and Sn adatoms on the surface originating from the thermal effect of substrate temperature, which also suggests that limiting the migration of deposited Ge and Sn adatoms can reduce the Sn surface segregation and improve the crystallinity of GeSn layers.

  12. Carrier and heat transport properties of polycrystalline GeSn films on SiO2

    Science.gov (United States)

    Uchida, Noriyuki; Maeda, Tatsuro; Lieten, Ruben R.; Okajima, Shingo; Ohishi, Yuji; Takase, Ryohei; Ishimaru, Manabu; Locquet, Jean-Pierre

    2015-12-01

    We evaluated the potential of polycrystalline (poly-) GeSn as channel material for the fabrication of thin film transistors (TFTs) at a low thermal budget (GeSn films with a grain size of ˜50 nm showed a carrier mobility of ˜30 cm2 V-1 s-1 after low-temperature annealing at 475-500 °C. Not only carrier mobility but also thermal conductivity of the films is important in assessing the self-heating effect of the poly-GeSn channel TFT. The thermal conductivity of the poly-GeSn films is 5-9 W m-1 K-1, which is significantly lower compared with 30-60 W m-1 K-1 of bulk Ge; this difference results from phonon scattering at grain boundaries and Sn interstitials. The poly-GeSn films have higher carrier mobility and thermal conductivity than poly-Ge films annealed at 600 °C, because of the improved crystal quality and coarsened grain size resulting from Sn-induced crystallization. Therefore, the poly-GeSn film is well-suited as channel material for TFTs, fabricated with a low thermal budget.

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

    Science.gov (United States)

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

    2016-09-01

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

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

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  15. Compositional dependence of optical interband transition energies in GeSn and GeSiSn alloys

    Science.gov (United States)

    Xu, Chi; Senaratne, Charutha L.; Kouvetakis, John; Menéndez, José

    2015-08-01

    The dielectric functions of GeSn and GeSiSn alloys were measured in the 1-6 eV energy range using spectroscopic ellipsometry. The contributions from the E1, E1 + Δ1, E0‧, E2, and E1‧ critical points in the joint density of electronic states were enhanced by computing numerical second derivatives of the measured dielectric function, and the resulting lineshapes were fitted with model expressions from which the critical point energies, amplitudes, broadenings, and phases were determined. A detailed analysis of the compositional dependence of the different transition energies is presented. By describing this dependence in terms of quadratic polynomials, the bowing parameter (quadratic coefficient) for each transition is determined. It is shown that the bowing parameters in the ternary alloy follow a distinct chemical trend, in which the ternary is well described in terms of bowing parameters for the underlying binary alloys, and these bowing parameters increase as a function of the size and electronegativity mismatch of the alloy constituents.

  16. Theoretical analysis of performance enhancement in GeSn/SiGeSn light-emitting diode enabled by Sisub>3sub>Nsub>4sub> liner stressor technique.

    Science.gov (United States)

    Zhang, Qingfang; Liu, Yan; Han, Genquan; Shao, Yao; Gao, Xi; Zhang, Chunfu; Zhang, Jincheng; Hao, Yue

    2016-12-01

    We comprehensively investigate the energy band diagrams, carrier distribution, spontaneous emission rate rsub>spsub>, and the internal quantum efficiency ηsub>IQEsub> in the lattice-matched GeSn/SiGeSn double heterostructure light-emitting diode (LED) wrapped in a Sisub>3sub>Nsub>4sub> liner stressor. The large tensile strain introduced into the device by the expansion of the Sisub>3sub>Nsub>4sub> liner is characterized by numerical simulation. A lower Sn composition required for the indirect to direct bandgap transition and a higher ratio of the electron occupation probability in the Γ conduction valley are achieved in the tensile strained GeSn/SiGeSn LED in comparison with the relaxed device. Analytical calculation shows that the tensile strained LED wrapped in the Sisub>3sub>Nsub>4sub> liner stressor exhibits the improved rsub>spsub> and ηsub>IQEsub> compared to the relaxed device. rsub>spsub> and ηsub>IQEsub> also can be enhanced by increasing Sn composition, carrier injection density, and n-type doping concentration in the GeSn active layer.

  17. Design of a Si-based lattice-matched room-temperature GeSn/GeSiSn multi-quantum-well mid-infrared laser diode.

    Science.gov (United States)

    Sun, G; Soref, R A; Cheng, H H

    2010-09-13

    This paper presents modeling and simulation of a silicon-based group IV semiconductor injection laser diode in which the active region has a multiple quantum well structure formed with Ge(0.9)Sn(0.1) quantum wells separated by Ge(0.75)Si(0.1)Sn(0.15) barriers. These alloy compositions were chosen to satisfy three conditions simultaneously: a direct band gap for Ge(0.9)Sn(0.1), type-I band alignment between Ge(0.9)Sn(0.1) and Ge(0.75)Si(0.1)Sn(0.15,) and a lattice match between wells and barriers. This match ensures that the entire structure can be grown strain free upon a relaxed Ge(0.75)Si(0.1)Sn(0.15) buffer on a silicon substrate - a CMOS compatible process. Detailed analysis is performed for the type I band offsets, carrier lifetime, optical confinement, and modal gain. The carrier lifetime is found to be dominated by the spontaneous radiative process rather than the Auger process. The modal gain has a rather sensitive dependence on the number of quantum wells in the active region. The proposed laser is predicted to operate at 2.3 μm in the mid infrared at room temperature.

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

    Science.gov (United States)

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

    2016-04-01

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

  19. As doping of Si-Ge-Sn epitaxial semiconductor materials on a commercial CVD reactor

    Science.gov (United States)

    Bhargava, Nupur; Margetis, Joe; Tolle, John

    2017-09-01

    In this work we present the As doping, via AsH3, of Ge1-x Sn x and SiyGe1-y-x Sn x alloys grown in a commercial RPCVD reactor. The composition, thickness, and resistivity of the layers were measured for varying AsH3 flows and AsH3 growth kinetics was discussed. We find that the addition of As to the lattice induces compressive strain in the layer despite a smaller covalent radius relative to Ge and Sn. N-type dopant incorporation and activation is compared for AsH3 and PH3-based processes, and we find that As incorporates more efficiently than P. As concentrations > 2 × 1020 cm-3 were achieved for both Ge1-x Sn x and SiyGe1-y-x Sn x with resistivity as low as 0.6 mΩ cm.

  20. Observation of field emission from GeSn nanoparticles epitaxially grown on silicon nanopillar arrays

    Science.gov (United States)

    Di Bartolomeo, Antonio; Passacantando, Maurizio; Niu, Gang; Schlykow, Viktoria; Lupina, Grzegorz; Giubileo, Filippo; Schroeder, Thomas

    2016-12-01

    We apply molecular beam epitaxy to grow GeSn-nanoparticles on top of Si-nanopillars patterned onto p-type Si wafers. We use x-ray photoelectron spectroscopy to confirm a metallic behavior of the nanoparticle surface due to partial Sn segregation as well as the presence of a superficial Ge oxide. We report the observation of stable field emission (FE) current from the GeSn-nanoparticles, with turn on field of 65 {{V}} μ {{{m}}}-{{1}} and field enhancement factor β ˜ 100 at anode-cathode distance of ˜0.6 μm. We prove that FE can be enhanced by preventing GeSn nanoparticles oxidation or by breaking the oxide layer through electrical stress. Finally, we show that GeSn/p-Si junctions have a rectifying behavior.

  1. Mid-Rapidity Protons in 158A$\\cdot$GeV Pb + Pb Collisions

    CERN Document Server

    Bearden, I G; Boissevain, J G; Dodd, J; Erazmus, B; Esumi, S C; Fabjan, Christian Wolfgang; Ferenc, D; Fields, D E; Franz, A; Gaardhøje, J J; Hansen, O; Hardtke, D; van Hecke, H; Holzer, E B; Humanic, T J; Hummel, P; Jacak, B V; Jayanti, R; Kaneta, M; Kopytine, M L; Leltchouk, M; Ljubicic, T; Lörstad, B; Maeda, N; Medvedev, A; Murray, M; Nishimura, S; Ohnishi, H; Paic, G; Pandey, S U; Piuz, François; Pluta, F; Polychronakos, V; Potekhin, M V; Poulard, G; Sakaguchi, A; Simon-Gillo, J; Schmidt-Sørensen, J; Sondheim, W E; Spegel, M; Sugitate, T; Sullivan, J P; Sumi, Y; Willis, W J; Wolf, K; Xu, N; Zachary, D S

    1996-01-01

    Proton distributions at mid-rapidity (2 $\\le y \\le$ 3) have been measured for 158A$\\cdot$GeV Pb + Pb collisions in the focusing spectrometer experiment NA44 at CERN. From baryon number conservation and by comparing the experimentally measured dN/dy distribution with the transport model RQMD, we conclude that a rather high degree of nuclear stopping has been reached for the truly heavy-ion collisions at these energies. Transverse mass distributions exhibit characteristically thermal shapes and the slope parameters increase with the mass of the colliding system.

  2. Two-kaon correlations in central Pb + Pb collisions at 158 A GeV/c

    CERN Document Server

    Sugitate, T; Bøggild, H; Boissevain, J; Christiansen, P H L; Conin, L; Dodd, J; Erazmus, B; Esumi, S; Fabjan, Christian Wolfgang; Ferenc, D; Franz, A; Gaardhøje, J J; Hansen, A G; Hansen, O; Hardtke, D; van Hecke, H; Holzer, E B; Humanic, T J; Hummel, P; Jacak, B V; Kaimi, K; Kaneta, M; Kohama, T; Kopytine, M; Leltchouk, M; Ljubicic, A; Lörstad, B; Maeda, N; Martin, L; Medvedev, A; Murray, M; Ohnishi, H; Paic, G; Pandey, S U; Piuz, François; Pluta, J; Polychronakos, V; Potekhin, M; Poulard, G; Reichhold, D; Sakaguchi, A; Schmidt-Sørensen, J; Simon-Gillo, J; Sondheim, W; Sullivan, J P; Sumi, Y; Willis, W J; Wolf, K; Xu, N; Zachary, D S

    2001-01-01

    Two-particle interferometry of positive kaons is studied in Pb + Pb collisions at mean transverse momenta $\\approx 0.25$ and 0.91 GeV/c. A three-dimensional analysis was applied to the lower $p_T$ data, while a two-dimensional analysis was used for the higher $p_T$ data. We find that the source size parameters are consistent with the $m_T$ scaling curve observed in pion correlation measurements in the same collisions, and that the duration time of kaon emission is consistent with zero within the experimental sensitivity.

  3. Particle production in central Pb+Pb collisions at 158A GeV/c

    CERN Document Server

    Bearden, I G; Boissevain, J G; Christiansen, P H L; Conin, L; Dodd, J; Erazmus, B; Esumi, S; Fabjan, Christian Wolfgang; Ferenc, D; Fields, D E; Franz, A; Gaardhøje, J J; Hamelin, M; Hansen, A G; Hansen, O; Hardtke, D; Holzer, E B; Humanic, T J; Hummel, P; Jacak, B V; Kaimi, K; Kaneta,1 M; Kohama, T; Kopytine, M; Leltchouk, M; Ljubicic, A; Lörstad, B; Maeda, N; Malina, R; Martin, L; Medvedev, A; Murray, M; Ohnishi, H; Paic, G; Pandey, S U; Piuz, François; Pluta, J; Polychronakos, V; Potekhin, M V; Poulard, G; Reichhold, D M; Sakaguchi, A; Schmidt-Sørensen, J; Simon-Gillo, J; Sondheim, W E; Spegel, M; Sugitate, T; Sullivan, J P; Sumi, Y; Willis, W J; Wolf, K L; Xu, N; Zachary, D S; van Hecke, H; Ljubicic, A Jr

    2002-01-01

    The NA44 experiment has measured single-particle inclusive spectra for charged pions, kaons, and protons as a function of transverse mass near midrapidity in 158A GeV/c Pb+Pb collisions. From the particle mass dependence of the observed m/sub T/ distributions, we are able to deduce a value of about 120 MeV for the temperature at thermal freeze-out. From the observed ratios of the rapidity densities, we find values of the chemical potentials for light and strange quarks and a chemical freeze-out temperature of approximately 140 MeV. (34 refs).

  4. Strangelet search in Pb-Pb interactions at 158 GeV/{ital c} per nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Appelquist, G.; Baglin, C.; Beringer, J.; Bohm, C.; Borer, K.; Bussiere, A.; Dittus, F.; Elsener, K.; Frei, D.; Gorodetzky, P.; Guillaud, J.P.; Hugentobler, E.; Klingenberg, R.; Linden, T.; Lohmann, K.D.; Moser, U.; Pal, T.; Pretzl, K.; Schacher, J.; Sellden, B.; Stoffel, F.; Tuominiemi, J.; Zhang, Q.P. [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland)]|[CERN, SL Division, CH-1211 Geneva 23 (Switzerland)]|[CNRS-IN2P3, LAPP Annecy, F-74941 Annecy-le-Vieux (France)]|[Department of Physics, University of Helsinki, P.O. Box 9, FIN-00014 Helsinki (Finland)]|[Department of Physics, University of Stockholm, P.O. Box 6730, S-11385 Stockholm (Sweden)]|[CNRS-IN2P3, CRN Strasbourg, F-67037 Strasbourg (France)

    1996-05-01

    The NA52 experiment searches for long-lived massive strange quark matter particles, so-called {ital strangelets}, produced in Pb-Pb collisions at a beam momentum of {ital p}{sub lab}=158 AGeV/{ital c}. Upper limits for the production of strangelets at zero degree production angle covering a mass to charge ratio up to 120 GeV/{ital c}{sup 2} and lifetimes {ital t}{sub lab}{approx_gt}1.2 {mu}s are given. The data presented here were taken during the 1994 lead beam running period at CERN. {copyright} {ital 1996 The American Physical Society.}

  5. Temperature varying photoconductivity of GeSn alloys grown by chemical vapor deposition with Sn concentrations from 4% to 11%

    Science.gov (United States)

    Hart, John; Adam, Thomas; Kim, Yihwan; Huang, Yi-Chiau; Reznicek, Alexander; Hazbun, Ramsey; Gupta, Jay; Kolodzey, James

    2016-03-01

    Pseudomorphic GeSn layers with Sn atomic percentages between 4.5% and 11.3% were grown by chemical vapor deposition using digermane and SnCl4 precursors on Ge virtual substrates grown on Si. The layers were characterized by x-ray diffraction rocking curves and reciprocal space maps. Photoconductive devices were fabricated, and the dark current was found to increase with Sn concentration. The responsivity of the photoconductors was measured at a wavelength of 1.55 μm using calibrated laser illumination at room temperature and a maximum value of 2.7 mA/W was measured for a 4.5% Sn device. Moreover, the responsivity for higher Sn concentration was found to increase with decreasing temperature. Spectral photoconductivity was measured using Fourier transform infrared spectroscopy. The photoconductive absorption edge continually increased in wavelength with increasing tin percentage, out to approximately 2.4 μm for an 11.3% Sn device. The direct band gap was extracted using Tauc plots and was fit to a bandgap model accounting for layer strain and Sn concentration. This direct bandgap was attributed to absorption from the heavy-hole band to the conduction band. Higher energy absorption was also observed, which was thought to be likely from absorption in the light-hole band. The band gaps for these alloys were plotted as a function of temperature. These experiments show the promise of GeSn alloys for CMOS compatible short wave infrared detectors.

  6. Assessment of density functionals and paucity of non-covalent interactions in aminoylyne complexes of molybdenum and tungsten [(η(5)-C5H5)(CO)2M≡EN(SiMe3)(R)] (E = Si, Ge, Sn, Pb): a dispersion-corrected DFT study.

    Science.gov (United States)

    Pandey, Krishna K; Patidar, Pankaj; Bariya, Pankaj K; Patidar, Sunil K; Vishwakarma, Ravi

    2014-07-14

    Electronic, molecular structure and bonding energy analyses of the metal-aminosilylyne, -aminogermylyne, -aminostannylyne and -aminoplumbylyne complexes [(η(5)-C5H5)(CO)2M[triple bond, length as m-dash]EN(SiMe3)(Ph)] (M = Mo, W) and [(η(5)-C5H5)(CO)2Mo[triple bond, length as m-dash]GeN(SiMe3)(Mes)] have been investigated at DFT, DFT-D3 and DFT-D3(BJ) levels using BP86, PBE, PW91, RPBE, TPSS and M06-L functionals. The performance of metaGGA functionals for the geometries of aminoylyne complexes is better than GGA functionals. Significant dispersion interactions between OH, EC(O) and EH pairs appeared in the dispersion-corrected geometries. The non-covalent distances of these interactions follow the order DFT > DFT-D3(BJ) > DFT-D3. The values of Nalewajski-Mrozek bond order (1.22-1.52) and Pauling bond order (2.23-2.59) of the optimized structures at BP86/TZ2P indicate the presence of multiple bonds between metal and E atoms. The overall electronic charges transfer from transition-metal fragments to ligands. The topological analysis based on QTAIM has been performed to determine the analogy of non-covalent interactions. The strength of M[triple bond, length as m-dash]EN(SiMe3)(R) bonds has been evaluated by energy decomposition analysis. The electrostatic interactions are almost equal to orbital interactions. The M ← E σ-donation is smaller than the M → E π-back donation. Upon going from E = Si to E = Pb, the M-E bond orders decrease as Si > Ge > Sn > Pb, consistent with the observed geometry trends. The M-E uncorrected bond dissociation energies vary with the density functionals as RPBE DFT-D3 dispersion corrections to the BDEs correspond to the BP86 functional, ranging between 5.6-8.1 kcal mol(-1), which are smaller than the DFT-D3(BJ) dispersion corrections (10.1-12.0 kcal mol(-1)). The aryl substituents on nitrogen have an insignificant effect on M-E-N bending. The bending of the M-E-N bond angle has been discussed in terms of Jahn-Teller distortion. The

  7. Defect-free high Sn-content GeSn on insulator grown by rapid melting growth

    Science.gov (United States)

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

    2016-12-01

    GeSn is an attractive semiconductor material for Si-based photonics. However, large lattice mismatch between GeSn and Si and the low solubility of Sn in Ge limit its development. In order to obtain high Sn-content GeSn on Si, it is normally grown at low temperature, which would lead to inevitable dislocations. Here, we reported a single-crystal defect-free graded GeSn on insulator (GSOI) stripes laterally grown by rapid melting growth (RMG). The Sn-content reaches to 14.2% at the end of the GSOI stripe. Transmission electron microscopy observation shows the GSOI stripe without stacking fault and dislocations. P-channel pseudo metal-oxide-semiconductor field effect transistors (MOSFETs) and metal-semiconductor-metal (MSM) Schottky junction photodetectors were fabricated on these GSOIs. Good transistor performance with a low field peak hole mobility of 402 cm2/Vs is obtained, which indicates a high-quality of this GSOI structure. Strong near-infrared and short-wave infrared optical absorption of the MSM photodetectors at 1550 nm and 2000 nm were observed. Owing to high Sn-content and defect-free, responsivity of 236 mA/W@-1.5 V is achieved at 1550 nm wavelength. In addition, responsivity reaches 154 mA/W@-1.5 V at 2000 nm with the optical absorption layer only 200 nm-thick, which is the highest value reported for GeSn junction photodetectors until now.

  8. Constitutive Behavior of Mixed Sn-Pb/Sn-3.0Ag-0.5Cu Solder Alloys

    Science.gov (United States)

    Tucker, J. P.; Chan, D. K.; Subbarayan, G.; Handwerker, C. A.

    2012-03-01

    During the transition from Pb-containing solders to Pb-free solders, joints composed of a mixture of Sn-Pb and Sn-Ag-Cu often result from either mixed assemblies or rework. Comprehensive characterization of the mechanical behavior of these mixed solder alloys resulting in a deformationally complete constitutive description is necessary to predict failure of mixed alloy solder joints. Three alloys with 1 wt.%, 5 wt.%, and 20 wt.% Pb were selected so as to represent reasonable ranges of Pb contamination expected from different 63Sn-37Pb components mixed with Sn-3.0Ag-0.5Cu. Creep and displacement-controlled tests were performed on specially designed assemblies at temperatures of 25°C, 75°C, and 125°C using a double lap shear test setup that ensures a nearly homogeneous state of plastic strain at the joint interface. The observed changes in creep and tensile behavior with Pb additions were related to phase equilibria and microstructure differences observed through differential scanning calorimetric and scanning electron microscopic cross-sectional analysis. As Pb content increased, the steady-state creep strain rates increased, and primary creep decreased. Even 1 wt.% Pb addition was sufficient to induce substantially large creep strains relative to the Sn-3.0Ag-0.5Cu alloy. We describe rate-dependent constitutive models for Pb-contaminated Sn-Ag-Cu solder alloys, ranging from the traditional time-hardening creep model to the viscoplastic Anand model. We illustrate the utility of these constitutive models by examining the inelastic response of a chip-scale package (CSP) under thermomechanical loading through finite-element analysis. The models predict that, as Pb content increases, total inelastic dissipation decreases.

  9. Ultrathin GeSn p-channel MOSFETs grown directly on Si(111) substrate using solid phase epitaxy

    Science.gov (United States)

    Maeda, Tatsuro; Jevasuwan, Wipakorn; Hattori, Hiroyuki; Uchida, Noriyuki; Miura, Shu; Tanaka, Masatoshi; Santos, Nuno D. M.; Vantomme, André; Locquet, Jean-Pierre; Lieten, Ruben R.

    2015-04-01

    Ultrathin GeSn layers with a thickness of 5.5 nm are fabricated on a Si(111) substrate by solid phase epitaxy (SPE) of amorphous GeSn layers with Sn concentrations up to 6.7%. We demonstrate well-behaved depletion-mode operation of GeSn p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) with an on/off ratio of more than 1000 owing to the ultrathin GeSn channel layer (5.5 nm). It is found that the on current increases significantly with increasing Sn concentration at the same gate overdrive, attributed to an increasing substitutional Sn incorporation in Ge. The GeSn (6.7%) layer sample shows approximately 90% enhancement in hole mobility in comparison with a pure Ge channel on Si.

  10. Thermodynamic Assessment of Interaction Relation between Lanthanum and Constituent Elements in Sn-Pb Alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The interaction relation between lanthanum and the constituent elements of Sn-Pb alloy system was analyzed by using the thermodynamic models including Miedema formation energy model for binary system, Tanaka modification by excess entropy and the Chou geometric model for ternary system. The thermodynamic calculaton results show that lanthanum has higher affinity for Sn in the Sn-Pb system. This is an important foundation for the improvement of the metallurgical properties of Sn-Pb solder alloy by adding rare earth elements.

  11. Synthesis and fundamental properties of stable Ph(3)SnSiH(3) and Ph(3)SnGeH(3) hydrides: model compounds for the design of Si-Ge-Sn photonic alloys.

    Science.gov (United States)

    Tice, Jesse B; Chizmeshya, Andrew V G; Groy, Thomas L; Kouvetakis, John

    2009-07-06

    The compounds Ph(3)SnSiH(3) and Ph(3)SnGeH(3) (Ph = C(6)H(5)) have been synthesized as colorless solids containing Sn-MH(3) (M = Si, Ge) moieties that are stable in air despite the presence of multiple and highly reactive Si-H and Ge-H bonds. These molecules are of interest since they represent potential model compounds for the design of new classes of IR semiconductors in the Si-Ge-Sn system. Their unexpected stability and high solubility also makes them a safe, convenient, and potentially useful delivery source of -SiH(3) and -GeH(3) ligands in molecular synthesis. The structure and composition of both compounds has been determined by chemical analysis and a range of spectroscopic methods including multinuclear NMR. Single crystal X-ray structures were determined and indicated that both compounds condense in a Z = 2 triclinic (P1) space group with lattice parameters (a = 9.7754(4) A, b = 9.8008(4) A, c = 10.4093(5) A, alpha = 73.35(10)(o), beta = 65.39(10)(o), gamma = 73.18(10)(o)) for Ph(3)SnSiH(3) and (a = 9.7927(2) A, b = 9.8005(2) A, c = 10.4224(2) A, alpha = 74.01(3)(o), beta = 65.48(3)(o), gamma = 73.43(3)(o)) for Ph(3)SnGeH(3). First principles density functional theory simulations are used to corroborate the molecular structures of Ph(3)SnSiH(3) and Ph(3)SnGeH(3), gain valuable insight into the relative stability of the two compounds, and provide correlations between the Si-Sn and Ge-Sn bonds in the molecules and those in tetrahedral Si-Ge-Sn solids.

  12. GeSn-on-insulator substrate formed by direct wafer bonding

    Science.gov (United States)

    Lei, Dian; Lee, Kwang Hong; Bao, Shuyu; Wang, Wei; Wang, Bing; Gong, Xiao; Tan, Chuan Seng; Yeo, Yee-Chia

    2016-07-01

    GeSn-on-insulator (GeSnOI) on Silicon (Si) substrate was realized using direct wafer bonding technique. This process involves the growth of Ge1-xSnx layer on a first Si (001) substrate (donor wafer) followed by the deposition of SiO2 on Ge1-xSnx, the bonding of the donor wafer to a second Si (001) substrate (handle wafer), and removal of the Si donor wafer. The GeSnOI material quality is investigated using high-resolution transmission electron microscopy, high-resolution X-ray diffraction (HRXRD), atomic-force microscopy, Raman spectroscopy, and spectroscopic ellipsometry. The Ge1-xSnx layer on GeSnOI substrate has a surface roughness of 1.90 nm, which is higher than that of the original Ge1-xSnx epilayer before transfer (surface roughness is 0.528 nm). The compressive strain of the Ge1-xSnx film in the GeSnOI is as low as 0.10% as confirmed using HRXRD and Raman spectroscopy.

  13. Microstructural evolution and tensile properties of Sn-Ag-Cu mixed with Sn-Pb solder alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang Fengjiang [Department of Materials Science and Engineering and Materials Research Center, Missouri University of Science and Technology, Rolla, MO 65401 (United States); O' Keefe, Matthew [Department of Materials Science and Engineering and Materials Research Center, Missouri University of Science and Technology, Rolla, MO 65401 (United States)], E-mail: mjokeefe@mst.edu; Brinkmeyer, Brandon [Department of Materials Science and Engineering and Materials Research Center, Missouri University of Science and Technology, Rolla, MO 65401 (United States)

    2009-05-27

    The effect of incorporating eutectic Sn-Pb solder with Sn-3.0Ag-0.5Cu (SAC) Pb-free solder on the microstructure and tensile properties of the mixed alloys was investigated. Alloys containing 100, 75, 50, 25, 20, 15, 10, 5 and 0 wt% SAC, with the balance being Sn-37Pb eutectic solder alloy, were prepared and characterized. Optical and scanning electron microscopy were used to analyze the microstructures while 'mini-tensile' test specimens were fabricated and tested to determine mechanical properties at the mm length scale, more closely matching that of the solder joints. Microstructural analysis indicated that a Pb-rich phase formed and was uniformly distributed at the boundary between the Sn-rich grains or between the Sn-rich and the intermetallic compounds in the solder. Tensile results showed that mixing of the alloys resulted in an increase in both the yield and the ultimate tensile strength compared to the original solders, with the 50% SAC-50% Sn-Pb mixture having the highest measured strength. Initial investigations indicate the formation and distribution of a Pb-rich phase in the mixed solder alloys as the source of the strengthening mechanism.

  14. Germylenes and stannylenes stabilized within N2PE rings (E = Ge or Sn): combined experimental and theoretical study.

    Science.gov (United States)

    Vrána, Jan; Ketkov, Sergey; Jambor, Roman; Růžička, Aleš; Lyčka, Antonín; Dostál, Libor

    2016-06-21

    The deprotonation of aminophosphanes PhP(NHR)2 (R = t-Bu or Dip; Dip = 2,6-i-Pr2C6H3) and t-BuP(NHDip)2 using n-BuLi gave, depending on the stoichiometry, both the dilithium compounds {[PhP(Nt-Bu)2]Li2}2 (), [PhP(Nt-Bu)(NDip)]Li2·(Et2O) (), [t-BuP(NDip)2]Li2·(Et2O)2 () and [t-BuP(NDip)2]Li2·(tmeda)2 (), and the monolithium compounds [PhP(NHt-Bu)(NR)]Li·(tmeda) (R = t-Bu , Dip ) and [t-BuP(NHDip)(NDip)]Li·(tmeda) (). Treatment of , and with GeCl2·dioxane or SnCl2 in a 1 : 1 stoichiometric ratio gave the corresponding tetrylenes [PhP(Nt-Bu)2]E (E = Ge , Sn ), [PhP(Nt-Bu)(NDip)]Ge () and [t-BuP(NDip)2]E (E = Ge , Sn ). The heteroleptic germylene [Ph(H)P(Nt-Bu)2]GeCl () was obtained by the reaction of the monolithium compound [PhP(NHt-Bu)(Nt-Bu)]Li·(tmeda) () with GeCl2·dioxane in a 1 : 1 stoichiometric ratio, as a result of a spontaneous NH → PH tautomeric shift in the ligand backbone. In contrast, an analogous reaction with SnCl2 produced only stannylene along with the PhP(NHt-Bu)2 starting material, suggesting scrambling of the ligands rather than a NH → PH tautomeric shift. Finally, heating in solution led to P-C bond cleavage and formation of the bis(imino)phosphide [DipNPNDip]Li·(tmeda) (). The reaction of with GeCl2·dioxane, SnCl2 or PbCl2 in a 2 : 1 stoichiometric ratio yielded the unprecedented tetrylenes [DipNPNDip]2E (E = Ge , Sn and Pb ), in which the tetrylene center is incorporated within two N2PE rings. Treatment of the monolithium compound with n-BuLi and K (or KC8) gave [t-BuNPNt-Bu]Li·(tmeda) () and{[t-BuNPNt-Bu]K(tmeda)}2 (), respectively. In contrast to the reaction with , similar reactions of with GeCl2·dioxane and SnCl2 resulted in the known compounds cis-[P(μ-Nt-Bu)2P(t-BuN)2]E (E = Ge, Sn); evidently the t-Bu groups do not provide sufficient steric shielding to protect the bis(imino)phosphide backbone as in the case of . The bonding situation in a set of selected compounds (, ) has been subjected to a theoretical

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

    Science.gov (United States)

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

    2012-02-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-22

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

  17. Theoretical study of projectile fragmentation in the reactions $^{112}$Sn + $^{112}$Sn and $^{124}$Sn + $^{124}$Sn at 1 GeV/nucleon

    CERN Document Server

    Imal, H; Buyukcizmeci, N; Ogul, R; Botvina, A S; Trautmann, W

    2014-01-01

    We analyze the production cross sections and isotopic distributions of projectile-like residues in the reactions $^{112}$Sn + $^{112}$Sn and $^{124}$Sn + $^{124}$Sn at an incident beam energy of 1 GeV/nucleon measured with the FRS fragment separator at the GSI laboratory. Calculations within the statistical multifragmentation model (SMM) for an ensemble of excited sources were performed with ensemble parameters determined previously for similar reactions at 600 MeV/nucleon. The obtained good agreement with the experiment establishes the universal properties of the excited spectator systems produced during the dynamical stage of the reaction. It is furthermore confirmed that a significant reduction of the symmetry-energy term at the freeze-out stage of reduced density and high temperature is necessary to reproduce the experimental isotope distributions. A trend of decreasing symmetry energy for large neutron-rich fragments of low excitation energy is interpreted as a nuclear-structure effect.

  18. MCNP6 Study of Fragmentation Products from 112Sn + 112Sn and 124Sn + 124Sn at 1 GeV/nucleon

    CERN Document Server

    Mashnik, Stepan G

    2013-01-01

    Isotope production cross sections from 112Sn + 112Sn and 124Sn + 124Sn reactions at 1 GeV/nucleon, which were measured recently at GSI using the heavy-ion accelerator SIS18 and the Fragment Separator (FRS), have been analyzed with the latest Los Alamos Monte-Carlo transport code MCNP6 using the LAQGSM03.03 event generator. MCNP6 reproduces reasonably well all the measured cross sections. Comparison of the MCNP6 results with the measured data and with calculations by a modification of the Los Alamos version of the Quark-Gluon String Model allowing for multifragmentation processes in the framework of the Statistical Multifragmentation Model (SMM) by Botvina and coauthors, as realized in the code LAQGSM03.S1, does not suggest unambiguous evidence of a multifragmentation signature.

  19. GeSn-based p-i-n photodiodes with strained active layer on a Si wafer

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, H. H.; Li, H.; Mashanov, V.; Yang, Y. J.; Cheng, H. H., E-mail: hhcheng@ntu.edu.tw [Center for Condensed Matter Sciences and Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 106, Taiwan (China); Chang, G. E. [Department of Mechanical Engineering, and Advanced Institute of Manufacturing with High-tech Innovations, National Chung Cheng University, Chiayi County 62102, Taiwan (China); Soref, R. A.; Sun, G. [Department of Physics, University of Massachusetts Boston, Boston, Massachusetts 02125 (United States)

    2013-12-02

    We report an investigation of GeSn-based p-i-n photodiodes with an active GeSn layer that is almost fully strained. The results show that (a) the response of the Ge/GeSn/Ge heterojunction photodiodes is stronger than that of the reference Ge-based photodiodes at photon energies above the 0.8 eV direct bandgap of bulk Ge (<1.55 μm), and (b) the optical response extends to lower energy regions (1.55–1.80 μm wavelengths) as characterized by the strained GeSn bandgap. A cusp-like spectral characteristic is observed for samples with high Sn contents, which is attributed to the significant strain-induced energy splitting of heavy and light hole bands. This work represents a step forward in developing GeSn-based infrared photodetectors.

  20. Infrared electroluminescence from GeSn heterojunction diodes grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-06-24

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

  1. Quantum-Confined Stark Effect Analysis of GeSn/SiGeSn Quantum Wells for Mid-Infrared Si-Based Electroabsorption Devices Based on Many-Body Theory

    OpenAIRE

    Fujisawa, Takeshi; Saitoh, Kunimasa

    2015-01-01

    Quantum-confined Stark effect (QCSE) of group IV Ge(Sn)/SiGe(Sn) quantum wells (QWs) on Si substrate is analyzed by microscopic many-body theory for mid-infrared (mid-IR) Si-based electroabsorption devices. To show the validity of the theory, QCSE of Ge/SiGe QW is investigated and very good agreement between theory and reported measured results is obtained. Next, the QCSE of GeSn/SiGeSn QWs is analyzed and the QW design for electroabsorption modulators to obtain large extinction ratio in mid-...

  2. Growth and Optical Properties of Direct Band Gap Ge/Ge0.87Sn0.13 Core/Shell Nanowire Arrays.

    Science.gov (United States)

    Assali, S; Dijkstra, A; Li, A; Koelling, S; Verheijen, M A; Gagliano, L; von den Driesch, N; Buca, D; Koenraad, P M; Haverkort, J E M; Bakkers, E P A M

    2017-03-08

    Group IV semiconductor optoelectronic devices are now possible by using strain-free direct band gap GeSn alloys grown on a Ge/Si virtual substrate with Sn contents above 9%. Here, we demonstrate the growth of Ge/GeSn core/shell nanowire arrays with Sn incorporation up to 13% and without the formation of Sn clusters. The nanowire geometry promotes strain relaxation in the Ge0.87Sn0.13 shell and limits the formation of structural defects. This results in room-temperature photoluminescence centered at 0.465 eV and enhanced absorption above 98%. Therefore, direct band gap GeSn grown in a nanowire geometry holds promise as a low-cost and high-efficiency material for photodetectors operating in the short-wave infrared and thermal imaging devices.

  3. Correlation of Bandgap Reduction with Inversion Response in (Si)GeSn/High-k/Metal Stacks.

    Science.gov (United States)

    Schulte-Braucks, C; Narimani, K; Glass, S; von den Driesch, N; Hartmann, J M; Ikonic, Z; Afanas'ev, V V; Zhao, Q T; Mantl, S; Buca, D

    2017-03-15

    The bandgap tunability of (Si)GeSn group IV semiconductors opens a new era in Si-technology. Depending on the Si/Sn contents, direct and indirect bandgaps in the range of 0.4-0.8 eV can be obtained, offering a broad spectrum of both photonic and low power electronic applications. In this work, we systematically studied capacitance-voltage characteristics of high-k/metal gate stacks formed on GeSn and SiGeSn alloys with Sn-contents ranging from 0 to 14 at. % and Si-contents from 0 to 10 at. % particularly focusing on the minority carrier inversion response. A clear correlation between the Sn-induced shrinkage of the bandgap energy and enhanced minority carrier response was confirmed using temperature and frequency dependent capacitance voltage-measurements, in good agreement with k.p theory predictions and photoluminescence measurements of the analyzed epilayers as reported earlier. The enhanced minority generation rate for higher Sn-contents can be firmly linked to the bandgap reduction in the GeSn epilayer without significant influence of substrate/interface effects. It thus offers a unique possibility to analyze intrinsic defects in (Si)GeSn epilayers. The extracted dominant defect level for minority carrier inversion lies approximately 0.4 eV above the valence band edge in the studied Sn-content range (0-12.5 at. %). This finding is of critical importance since it shows that the presence of Sn by itself does not impair the minority carrier lifetime. Therefore, the continuous improvement of (Si)GeSn material quality should yield longer nonradiative recombination times which are required for the fabrication of efficient light detectors and to obtain room temperature lasing action.

  4. Optical Properties and Characterization of Prepared Sn-Doped PbSe Thin Film

    Directory of Open Access Journals (Sweden)

    M. R. Khanlary

    2012-01-01

    Full Text Available Physical vapor deposition of tin-doped lead selenide (Sn/PbSe thin films on SiO2 glass is described. Interaction of high-energy Ar+ ions bombardment on the doped PbSe films is discussed by XRD analysis. The improvement of optical band gap of Sn/PbSe films irradiated by different doses of irradiation was studied using transmission spectroscopy.

  5. Epitaxial Technologies for SiGeSn High Performance Optoelectronic Devices

    Science.gov (United States)

    2015-04-29

    a) (b) (c) Fig. 24 (a) Schematic cross -section of a GeSn/Si APD with a SACM structure and its internal electric field distribution. (b...shrinkage has been observed in heavily doped n-type samples. GeSn samples have been fabricated into photoconductive detectors, avalanche photo diodes , and...light-emitting diodes (LEDs) and in-depth study has been conducted. The responsivity of 1.63 A/W at 1.55 μm has been achieved with a Ge0.9Sn0.1

  6. Absorption coefficients of GeSn extracted from PIN photodetector response

    Science.gov (United States)

    Ye, Kaiheng; Zhang, Wogong; Oehme, Michael; Schmid, Marc; Gollhofer, Martin; Kostecki, Konrad; Widmann, Daniel; Körner, Roman; Kasper, Erich; Schulze, Jörg

    2015-08-01

    In this paper the optical absorption of the GeSn PIN photodetector was investigated. The vertical GeSn PIN photodetectors were fabricated by molecular beam epitaxy (MBE) and dry etching. By means of current density-voltage (J-V) and capacity-voltage (C-V) measurements the photodetector device was characterized. The absorption coefficients of GeSn material were finally extracted from the optical response of PIN structure. With further direct bandgap analysis the influences of device structure was proved negligible.

  7. Tuning between mixing and reactivity in the Ge-Sn system using pressure and temperature.

    Science.gov (United States)

    Guillaume, Christophe; Serghiou, George; Thomson, Andrew; Morniroli, Jean-Paul; Frost, Dan J; Odling, Nicholas; Mezouar, Mohamed

    2009-06-10

    No bulk GeSn crystal existed prior to this work. Near 10 GPa the two elements resemble each other both electronically and structurally. Synthesis experiments at 10 GPa and 1500 K followed by annealing at 770 K using Ge and Sn starting materials and ex-situ analysis using transmission electron microscopy, scanning electron microscopy, and X-ray diffraction document the recovery of a Ge(0.9)Sn(0.1) solid solution (space group P4(3)2(1)2, a = 6.014 (1) A, c = 7.057 (1) A, Z = 12).

  8. High pressure differential conductance measurements of (Pb,Sn)Se

    Science.gov (United States)

    Paul, Tiffany; Vangennep, Derrick; Jackson, Daniel; Biswas, Amlan; Hamlin, James

    Topological transitions have been recognized as a new type of quantum phase transition. Recently, a number of papers have reported scanning tunneling microscope (STM) measurements of the Landau level spectra of topologically non-trivial materials. Such measurements can offer substantial insight into the nature of the transition between topologically distinct phases. Although applied pressure represents an attractive means to drive a topological quantum phase transition, STM measurements can not be performed under high pressure conditions. In this talk, I will discuss our recent attempts to observe Landau level spectra in compressed (Pb,Sn)Se using differential conductance measurements. Acknowledgements: TAP supported by REU NSF DMR-1461019. Pressure cell development and measurements at high magnetic fields supported by the National High Magnetic Field Laboratory User Collaboration Grants Program. Synthesis, characterization, and high pressure measurements supported by NSF DMR-1453752.

  9. Realistic shell model; 132Sn region; 208Pb region

    CERN Document Server

    Covello, A; Gargano, A; Itaco, N

    2008-01-01

    We report on a study of exotic nuclei around doubly magic 132Sn in terms of the shell model employing a realistic effective interaction derived from the CD-Bonn nucleon-nucleon potential. The short-range repulsion of the latter is renormalized by constructing a smooth low-momentum potential, V-low-k, that is used directly as input for the calculation of the effective interaction. In this paper, we focus attention on proton-neutron multiplets in the odd-odd nuclei 134Sb, 136Sb. We show that the behavior of these multiplets is quite similar to that of the analogous multiplets in the counterpart nuclei in the 208Pb region, 210Bi and 212Bi.

  10. Insulators for Pb(1-x)Sn(x)Te

    Science.gov (United States)

    Tsuo, Y. H.; Sher, A.

    1981-01-01

    Thin films of LaF3 were e-gun and thermally deposited on several substrates. The e-gun deposited films are fluorine deficient, have high ionic conductivities that persist to 77 K, and high effective dielectric constants. The thermally deposited material tends to be closer to stoichiometric, and have higher effective breakdown field strengths. Thermally deposited LaF3 films with resistivities in excess of 10 to the 12th power ohms - cm were deposited on metal coated glass substrates. The LaF3 films were shown to adhere well to PbSnTe, surviving repeated cycles between room temperature and 77 K. The LaF3 films on GaAs were also studied.

  11. The NA52 strangelet and particle search in Pb+Pb collisions at 158 A GeV/c

    Science.gov (United States)

    Weber, M.; NA52 Collaboration; Arsenescu, R.; Baglin, C.; Beck, H. P.; Borer, K.; Bussière, A.; Elsener, K.; Gorodetzky, Ph; Guillaud, J. P.; Kabana, S.; Klingenberg, R.; Lehmann, G.; Lindén, T.; Lohmann, K. D.; Mommsen, R.; Moser, U.; Pretzl, K.; Schacher, J.; Spiwoks, R.; Tuominiemi, J.; Weber, M.

    2002-07-01

    The NA52 experiment searched for long-lived charged strangelets in 158 A GeV/c Pb+Pb collisions at CERN SPS. We collected 1013 Pb+Pb interactions looking for negatively charged strangelets and 3 × 1011 Pb+Pb interactions for positively charged ones. No evidence for the production of strangelets has been observed. The upper strangelet production limits are discussed. Besides the strangelet searches NA52 was able to identify particles and anti-particles over a wide range in rapidity. Results of the invariant differential particle production cross sections including fragments up to carbon and 5 0954-3899/28/7/347/hebar_1 are presented.

  12. Effect of Sn content on the properties of passive film on PbSn alloy in sulfuric acid solution

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effect of Sn content on properties of anodic film formed on PbSn alloys in sulfuric acid solution was investigated using linear sweeping voltage (LSV), cyclic voltammetry (CV), and a.c. voltammetry (ACV), based on the Mott-Schottky analysis. The results revealed that the addition of Sn into lead alloys can promote the corrosion resistance property and could decrease the impedance of anodic film; these results were more remarkable with enhancing the Sn content. The over potential of oxygen evolution on lead alloys enhanced with the increase of Sn content. The Mott-Schottky analysis indicated that the passive film appeared an n-type semiconductor, and the donor density of passive film increased with increasing Sn content. The increased vacancies in the passive film with Sn content increasing could illustrate this trend.

  13. Theoretical calculation of performance enhancement in lattice-matched SiGeSn/GeSn p-channel tunneling field-effect transistor with type-II staggered tunneling junction

    Science.gov (United States)

    Wang, Hongjuan; Han, Genquan; Wang, Yibo; Peng, Yue; Liu, Yan; Zhang, Chunfu; Zhang, Jincheng; Hu, Shengdong; Hao, Yue

    2016-04-01

    In this work, a lattice-matched SiGeSn/GeSn heterostructure p-channel tunneling field-effect transistor (hetero-PTFET) with a type-II staggered tunneling junction (TJ) is investigated theoretically. Lattice matching and type-II band alignment at the Γ-point is obtained at the SiGeSn/GeSn interface by tuning Sn and Si compositions. A steeper subthreshold swing (SS) and a higher on state current (I ON) are demonstrated in SiGeSn/GeSn hetero-PTFET than in GeSn homo-PTFET. Si0.31Ge0.49Sn0.20/Ge0.88Sn0.12 hetero-PTFET achieves a 2.3-fold higher I ON than Ge0.88Sn0.12 homo-PTFET at V DD of 0.3 V. Hetero-PTFET achieves a more abrupt hole profile and a higher carrier density near TJ than the homo-PTFET, which contributes to the significantly enhanced band-to-band tunneling (BTBT) rate and tunneling current in hetero-PTFET.

  14. Stoichiometry dependence of resistance drift phenomena in amorphous GeSnTe phase-change alloys

    Science.gov (United States)

    Luckas, J.; Piarristeguy, A.; Bruns, G.; Jost, P.; Grothe, S.; Schmidt, R. M.; Longeaud, C.; Wuttig, M.

    2013-01-01

    In phase-change materials, the amorphous state resistivity increases with time following a power law ρ ∝ (t/t0)αRD. This drift in resistivity seriously hampers the potential of multilevel-storage to achieve an increased capacity in phase-change memories. This paper presents the stoichiometric dependence of drift phenomena in amorphous GeSnTe systems (a-GeSnTe) and other known phase-change alloys with the objective to identify low drift materials. The substitution of Ge by Sn results in a systematic decrease of the drift parameter from a-GeTe (αRD = 0.129) to a-Ge2Sn2Te4 (αRD = 0.053). Furthermore, with increasing Sn content a decrease in crystallization temperature, trap state density, optical band gap, and activation energy for electronic conduction is observed. In a-GeSnTe, a-GeSbTe, and a-AgInSbTe alloys as well, the drift parameter αRD correlates to the activation energy for electronic conduction. This study indicates that low drift materials are characterized by low activation energies of electronic conduction. The correlation found between drift and activation energy of electronic conduction manifests a useful criterion for material optimization.

  15. Next Generation, Si-Compatible Materials and Devices in the Si-Ge-Sn System

    Science.gov (United States)

    2015-10-09

    performed extensive growth studies aimed to create entire new families of Ge1-x-ySixSny materials on industrially compatible group IV platforms ( Si , Ge and...AFRL-AFOSR-VA-TR-2016-0044 Next generation, Si -compatible materials and devices in the Si -Ge-Sn system John Kouvetakis ARIZONA STATE UNIVERSITY Final...4. TITLE AND SUBTITLE Next generation, Si -compatible materials and devices in the Si -Ge-Sn system 5a. CONTRACT NUMBER FA9550-12-1-0208 5b. GRANT

  16. Chemical Environment of Unusually Ge- and Pb-Rich Willemite, Tres Marias Mine, Mexico

    Directory of Open Access Journals (Sweden)

    Bernhardt Saini-Eidukat

    2016-03-01

    Full Text Available The Tres Marias carbonate-hosted Zn-Ge deposit in Chihuahua, Mexico contains willemite [Zn2SiO4] with unusually high concentrations of minor and trace elements (e.g., Pb, Ge, As, P, V; Pb concentrations are as high as 2 wt %, and Ge may reach 4000 ppm (average 900 ppm. Electron microprobe analyses and synchrotron X-ray fluorescence maps show that Zn and Ge, as well as Zn and Pb are negatively correlated, whereas Ge and Pb are positively correlated across zoned willemite crystals. In cathodoluminescence (CL images, those areas of willemite having high trace element concentrations have no, or low CL intensities, whereas zones low in trace elements (except for P display bright blue CL colors. X-ray absorption fine structure (XAFS spectroscopy was used to characterize the chemical nature of Ge and Pb in willemite. Comparisons to reference spectra of natural and artificial substances points to the presence of Ge4+ and Pb2+ in Tres Marias willemite. No evidence for Pb4+ was detected. Oscillatory zonation reflects trace element incorporation into willemite from the oxidation of primary Ge-bearing sphalerite and galena (PbS by siliceous aqueous fluids.

  17. Defect and dislocation structures in low-temperature-grown Ge and Ge{sub 1−x}Sn{sub x} epitaxial layers on Si(110) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kidowaki, Shohei [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Asano, Takanori [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Research Fellow of Japan Society for the Promotion of Science, 5-3-1, Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Shimura, Yosuke [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kurosawa, Masashi [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Taoka, Noriyuki [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Nakatsuka, Osamu, E-mail: nakatuka@alice.xtal.nagoya-u.ac.jp [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Zaima, Shigeaki [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2016-01-01

    We have investigated the epitaxial growth and crystalline properties of Ge{sub 1−x}Sn{sub x} layers on a Si(110) substrate. We found that the twin growth in the Ge epitaxial layer deposited on the Si(110) using molecular beam epitaxy at a low temperature of 200 °C can be effectively suppressed by the incorporation of 2.0% Sn. We also examined the strain relaxation of annealed Ge{sub 1−x}Sn{sub x}/Si(110) samples. The degree of strain relaxation is enhanced by the annealing process, and the threading dislocation in the Ge{sub 1−x}Sn{sub x} layers decreases from 10{sup 11} cm{sup −2} to 10{sup 10} cm{sup −2} because of the propagation of misfit dislocations. We also observed misfit dislocations formed at the Ge{sub 1−x}Sn{sub x}/Si interface, which would effectively promote isotropic strain relaxation in the Ge{sub 1−x}Sn{sub x} layers. - Highlights: • Suppression of twin in GeSn growth on Si(110) substrate • Isotropic strain relaxation of Ge and GeSn layers by misfit dislocation network • Achievement of high quality GeSn epitaxial layers on Si(110) by post deposition annealing.

  18. Transverse energy production in {sup 208}Pb+Pb collisions at 158 GeV per nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Alber, T.; Appelshaeuser, H.; Baechler, J.; Bartke, J.; Bialkowska, H.; Bieser, F.; Bloomer, M.A.; Blyth, C.O.; Bock, R.; Bormann, C.; Brady, F.P.; Brockmann, R.; Buncic, P.; Caines, H.L.; Cebra, D.; Chan, P.; Cooper, G.E.; Cramer, J.G.; Cramer, P.B.; Csato, P.; Derado, I.; Dunn, J.; Eckardt, V.; Eckhardt, F.; Euler, S.; Ferguson, M.I.; Fischer, H.G.; Fodor, Z.; Foka, P.; Freund, P.; Fuchs, M.; Gal, J.; Gazdzicki, M.; Gladysz, E.; Grebieszkow, J.; Guenther, J.; Harris, J.W.; Heck, W.; Hegyi, S.; Hill, L.A.; Huang, I.; Howe, M.A.; Igo, G.; Irmscher, D.; Jacobs, P.; Jones, P.G.; Kadija, K.; Kecskemeti, J.; Kowalski, M.; Kuehmichel, A.; Lasiuk, B.; Margetis, S.; Mitchell, J.W.; Mock, A.; Nelson, J.M.; Odyniec, G.; Palinkas, J.; Palla, G.; Panagiotou, A.D.; Petridis, A.; Piper, A.; Poskanzer, A.M.; Prindle, D.J.; Puehlhofer, F.; Rauch, W.; Renfordt, R.; Retyk, W.; Ritter, H.G.; Roehrich, D.; Rudolph, H.; Runge, K.; Sandoval, A.; Sann, H.; Schaefer, E.; Schmitz, N.; Schoenfelder, S.; Seyboth, P.; Seyerlein, J.; Sikler, F.; Skrzypczak, E.; Stock, R.; Stroebele, H.; Szentpetery, I.; Sziklai, J.; Toy, M.; Trainor, T.A.; Trentalange, S.; Vassiliou, M.; Vesztergombi, G.; Vranic, D.; Wenig, S.; Whitten, C.; Wienold, T.; Wood, L.; Zimanyi, J.; Zhu, X.; Zybert, R. [Department of Physics, University of Athens, Athens (Greece)]|[Lawrence Berkeley Laboratory, University of California, Berkeley California (United States)]|[Birmingham University, Birmingham (United Kingdom)]|[Institute of Physics, Budapest (Hungary)]|[CERN, Geneva (Switzerland)]|[Institute of Nuclear Physics, Cracow (Poland)]|[Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany)]|[University of California at Davis, Davis California (United States)]|[Fachbereich Physik der Universitaet, Frankfurt (Germany)]|[Fachbereich Physik der Universitaet, Freiburg (Germany)]|[University of California at Los Angeles, Los Angeles California (United States)

    1995-11-20

    Measurements of the forward and the transverse energy in 158 GeV per nucleon {sup 208}Pb+Pb collisions are presented. A total transverse energy of about 1 TeV is created in central collisions. An energy density of about 3GeV/fm{sup 3} is estimated for near head-on collisions. Only statistical fluctuations are seen in the ratio of electromagnetic to hadronic transverse energy. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

  19. Oxidation and reduction kinetics of eutectic SnPb, InSn, and AuSn: a knowledge base for fluxless solder bonding applications

    DEFF Research Database (Denmark)

    Kuhmann, Jochen Friedrich; Preuss, A.; Adolphi, B.;

    1998-01-01

    For microelectronics and especially for upcoming new packaging technologies in micromechanics and photonics fluxless, reliable and economic soldering technologies are needed. In this article, we consequently focus on the oxidation and reduction kinetics of three commonly used eutectic solder allo...... and reflowed AuSn(80/20) and SnPb(60/40) after the introduction of H2...

  20. First-principles calculations of optical properties of GeC, SnC and GeSn under hydrostatic pressure

    Energy Technology Data Exchange (ETDEWEB)

    Sahnoun, M. [Applied Materials Laboratory (AML), Electronics Department, University of Sidi-Bel-Abbes, 22000 (Algeria); Khenata, R. [Applied Materials Laboratory (AML), Electronics Department, University of Sidi-Bel-Abbes, 22000 (Algeria)]. E-mail: khenata_rabah@yahoo.fr; Baltache, H. [Applied Materials Laboratory (AML), Electronics Department, University of Sidi-Bel-Abbes, 22000 (Algeria); Rerat, M. [Laboratoire de Chimie Theorique et Physico-Chimie Moleculaire, UMR 5624, Universite de Pau, 64000 Pau (France)]. E-mail: michel.rerat@univ-pau.fr; Driz, M. [Laboratoire de Physique Quantique et de Modelisation Mathematique (LPQ3M), Departement de Technologie, Universite de Mascara, 29000 (Algeria); Bouhafs, B. [Computational Materials Science Laboratory, Physics Department, University of Sidi-Bel-Abbes, 22000 (Algeria); Abbar, B. [Computational Materials Science Laboratory, Physics Department, University of Sidi-Bel-Abbes, 22000 (Algeria)

    2005-01-31

    We present first-principles of the full-potential linearized augmented plane wave calculations of the effect of hydrostatic pressure on the optical properties of zinc-blende GeC, SnC and GeSn compounds. The refractive index and its variation with hydrostatic pressure are well described. An accurate calculation of linear optical functions (refraction index and its pressure derivative, and both imaginary and real parts of the dielectric function) is performed in the photon energy range up to 15 eV. The predicted optical constants agree well with the available experimental and theoretical ones.

  1. Full potential linearized augmented plane wave calculations of structural and electronic properties of GeC, SnC and GeSn

    Energy Technology Data Exchange (ETDEWEB)

    Khenata, R.; Baltache, H.; Sahnoun, M.; Driz, M.; Rerat, M.; Abbar, B

    2003-08-01

    A theoretical study of structural and electronic properties of GeC, SnC and GeSn is presented using the full potential linearized augmented plane wave method. In this approach, the generalized gradient approximation was used for the exchange-correlation potential. Results are given for lattice constant, bulk modulus and its pressure derivative in both zinc-blende and rocksalt structures. Band structure, density of states and band gap pressure coefficients in zinc-blende structure are also given. The results are compared with previous calculations and with experimental measurements.

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

    Science.gov (United States)

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

    2016-05-01

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

  3. Hadronic Expansion Dynamics in Central Pb+Pb Collisions at 158 GeV per Nucleon

    CERN Document Server

    Appelshäuser, H; Bailey, S J; Barnby, L S; Bartke, Jerzy; Barton, R A; Bialkowska, H; Billmeier, A; Blyth, C O; Bock, R; Bormann, C; Brady, F P; Brockmann, R; Brun, R; Buncic, P; Caines, H L; Cebra, D; Cooper, G E; Cramer, J G; Csató, P; Dunn, J; Eckardt, V; Eckhardt, F; Ferguson, M I; Ferenc, D; Fischer, H G; Flierl, D; Fodor, Z; Foka, P Y; Freund, P; Friese, V; Fuchs, M; Gabler, F; Gál, J; Gazdzicki, M; Gladysz-Dziadus, E; Grebieszkow, J; Günther, J; Harris, J W; Hegyi, S; Henkel, T; Hill, L A; Huang, I; Hümmler, H; Igo, G; Irmscher, D; Jacobs, P; Jones, P G; Kadija, K; Kolesnikov, V I; Kowalski, M; Lasiuk, B; Lévai, Peter; Malakhov, A I; Margetis, S; Markert, C; Melkumov, G L; Mock, A; Molnár, J; Nelson, J M; Oldenburg, M; Odyniec, Grazyna Janina; Pálla, G; Panagiotou, A D; Petridis, A; Piper, A; Porter, R J; Poskanzer, A M; Poziombka, S; Prindle, D J; Pühlhofer, F; Rauch, W; Reid, J G; Renfordt, R E; Retyk, W; Ritter, H G; Röhrich, D; Roland, C; Roland, G; Rudolph, H; Rybicki, A; Sandoval, A; Sann, H; Semenov, A Yu; Schäfer, E; Schmischke, D; Schmitz, N; Schönfelder, S; Seyboth, P; Seyerlein, J; Siklér, F; Skrzypczak, E; Squier, G T A; Stock, Reinhard; Ströbele, H; Struck, C; Szentpétery, I; Sziklai, J; Toy, M; Trainor, T A; Trentalange, S; Ullrich, T S; Vassiliou, Maria; Vesztergombi, G; Vranic, D; Wang, F; Weerasundara, D D; Wenig, S; Whitten, C; Wienold, T; Wood, L; Yates, T A; Xu, N; Zimányi, J; Zhu, X Z; Zybert, R

    1998-01-01

    Two-particle correlation functions of negative hadrons over wide phase space, and transverse mass spectra of negative hadrons and deuterons near mid-rapidity have been measured in central Pb+Pb collisions at 158 GeV per nucleon by the NA49 experiment at the CERN SPS. A novel Coulomb correction procedure for the negative two-particle correlations is employed making use of the measured oppositely charged particle correlation. Within an expanding source scenario these results are used to extract the dynamic characteristics of the hadronic source, resolving the ambiguities between the temperature and transverse expansion velocity of the source, that are unavoidable when single and two particle spectra are analysed separately. The source shape, the total duration of the source expansion, the duration of particle emission, the freeze-out temperature and the longitudinal and transverse expansion velocities are deduced.

  4. Elliptic flow of Lambda hyperons in Pb+Pb collisions at 158A GeV

    CERN Document Server

    Stefanek, G; Anticic, T; Baatar, B; Barna, D; Bartke, Jerzy; Betev, L; Bialkowska, H; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Buncic, P; Cerny, V; Christakoglou, P; Chvala, O; Cramer, J G; Csató, P; Dinkelaker, P; Eckardt, V; Flierl, D; Fodor, Z; Foka, P; Friese, V; Gál, J; Gazdzicki, M; Georgopoulos, G; Gladysz-Dziadus, E; Grebieszkow, K; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kliemant, M; Kniege, S; Kolesnikov, V I; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Laszlo, A; Van Leeuwen, M; Lévai, Peter; Litov, L; Lungwitz, B; Makariev, M; Malakhov, A I; Mateev, M; Melkumov, G L; Mischke, A; Mitrovski, M; Molnár, J; Mrówczynski, S; Nicolic, V; Pálla, G; Panagiotou, A D; Panayotov, D; Petridis, A; Pikna, M; Prindle, D; Pühlhofer, F; Renfordt, R; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Schuster, T; Seyboth, P; Siklér, F; Sitár, B; Skrzypczak, E; Stock, R; Strabel, C; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Szymanski, P; Trubnikov, V; Varga, D; Vassiliou, Maria; Veres, G I; Vesztergombi, G; Vranic, D; Wetzler, A; Wlodarczyk, Z; Wojtaszek, A; Yoo, I K; Zimányi, J

    2007-01-01

    The elliptic flow of Lambda hyperons has been measured by the NA49 experiment at the CERN-SPS in semi-central Pb+Pb collisions at 158A GeV. The standard method of correlating particles with the event plane was used. Measurements of v2 near mid-rapidity are reported as a function of rapidity, centrality and transverse momentum. Elliptic flow of Lambda particles increases both with the impact parameter and with the transverse momentum. It is compared with v2 for pions and protons as well as with model calculations. The observation of large elliptic flow and its mass dependence suggest strong collective behaviour of the matter produced in collisions of heavy nuclei already at the SPS.

  5. Search for strangelets in Pb+Pb collisions at 158 A GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Arsenescu, R [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Baglin, C [CNRS-IN2P3, LAPP Annecy, F-74941 Annecy-le-Vieux (France); Beck, H P [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Borer, K [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Bussiere, A [CNRS-IN2P3, LAPP Annecy, F-74941 Annecy-le-Vieux (France); Elsener, K [CERN, SL Division, CH-1211 Geneva (Switzerland); Gorodetzky, Ph [SPCC - College de France, 11 Place Marcellin Berthelod, 75005 Paris (France); Guillaud, J P [CNRS-IN2P3, LAPP Annecy, F-74941 Annecy-le-Vieux (France); Kabana, S [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Klingenberg, R [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Lehmann, G [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Linden, T [Helsinki Insitute of Physics, PO Box 9, FIN-00014 Helsinki (Finland); Lohmann, K D [CERN, SL Division, CH-1211 Geneva (Switzerland); Mommsen, R [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Moser, U [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Pretzl, K [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Schacher, J [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Spiwoks, R [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Tuominiemi, J [Helsinki Insitute of Physics, PO Box 9, FIN-00014 Helsinki (Finland); Weber, M [Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland)

    2002-11-01

    The NA52 experiment at CERN has investigated lead-lead collisions at 158 A GeV/c and searched for long-lived strange quark matter droplets, so-called strangelets, with a unique signature of a high mass-to-charge ratio. This ratio was measured in a focusing spectrometer equipped with a time-of-flight system. A total of 3x10{sup 11} Pb + Pb interactions at positive and 10{sup 13} at negative spectrometer polarities have been recorded. No strangelet has been observed, which sets experimental upper limits (90% CL) for the strangelet production at 3x10{sup -9} per interaction for positively charged and at 2x10{sup -10} per interaction for negatively charged strangelets.

  6. Search for strangelets in Pb + Pb collisions at 158 A GeV/c

    Science.gov (United States)

    Arsenescu, R.; Baglin, C.; Beck, H. P.; Borer, K.; Bussière, A.; Elsener, K.; Gorodetzky, Ph; Guillaud, J. P.; Kabana, S.; Klingenberg, R.; Lehmann, G.; Lindén, T.; Lohmann, K. D.; Mommsen, R.; Moser, U.; Pretzl, K.; Schacher, J.; Spiwoks, R.; Tuominiemi, J.; Weber, M.

    2002-11-01

    The NA52 experiment at CERN has investigated lead-lead collisions at 158 A GeV/c and searched for long-lived strange quark matter droplets, so-called strangelets, with a unique signature of a high mass-to-charge ratio. This ratio was measured in a focusing spectrometer equipped with a time-of-flight system. A total of 3×1011 Pb + Pb interactions at positive and 1013 at negative spectrometer polarities have been recorded. No strangelet has been observed, which sets experimental upper limits (90% CL) for the strangelet production at 3×10-9 per interaction for positively charged and at 2×10-10 per interaction for negatively charged strangelets.

  7. Development of a new Pb-free solder: Sn-Ag-Cu

    Energy Technology Data Exchange (ETDEWEB)

    Miller, C.M.

    1995-02-10

    With the ever increasing awareness of the toxicity of Pb, significant pressure has been put on the electronics industry to get the Pb out of solder. This work pertains to the development and characterization of an alloy which is Pb-free, yet retains the proven positive qualities of current Sn-Pb solders while enhancing the shortcomings of Sn-Pb solder. The solder studied is the Sn-4.7Ag-1.7Cu wt% alloy. By utilizing a variety of experimental techniques the alloy was characterized. The alloy has a melting temperature of 217{degrees}C and exhibits eutectic melting behavior. The solder was examined by subjecting to different annealing schedules and examining the microstructural stability. The effect of cooling rate on the microstructure of the solder was also examined. Overall, this solder alloy shows great promise as a viable alternative to Pb-bearing solders and, as such, an application for a patent has been filed.

  8. Synthesis of Ge1- x Sn x Alloy Thin Films Using Ion Implantation and Pulsed Laser Melting (II-PLM)

    Science.gov (United States)

    Bhatia, A.; Hlaing Oo, W. M.; Siegel, G.; Stone, P. R.; Yu, K. M.; Scarpulla, M. A.

    2012-05-01

    Ge1- x Sn x thin films are interesting for all-group-IV optoelectronics because of a crossover to a direct bandgap with dilute Sn alloying. However, Sn has vanishing room-temperature equilibrium solubility in Ge, making their synthesis very challenging. Herein, we report on our attempts to synthesize Ge1- x Sn x films on Ge (001) using ion implantation and pulsed laser melting (II-PLM). A maximum of 2 at.% Sn was incorporated with our experimental conditions in the samples as determined by Rutherford back scattering spectroscopy. A red-shift in the Ge optical phonon branch and increased absorption below the Ge bandgap with increasing Sn concentration indicate Sn-induced lattice- and band-structure changes after II-PLM. However, ion-channeling and electron microscopy show that the films are not of sufficient epitaxial quality for use in devices.

  9. Study of High-Quality GeSn Alloys Grown by Chemical Vapor Deposition towards Mid-Infrared Applications

    Science.gov (United States)

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

    2016-12-01

    Germanium-tin (GeSn) films with Sn compositions from 5% to 11% were grown on Ge-buffered Si using a reduced pressure chemical vapor deposition system with low-cost SnCl4 and GeH4 precursors. Material characterization showed that relaxed GeSn layers with thicknesses ranging from 400 nm to 1 μm were achieved. The strong photoluminescence (PL) intensity and the low defect density indicated very high material quality. In addition, temperature-dependent 10-300 K photoluminescence spectra showed that, due to strain relaxation of the material, the emission wavelength is longer than that of strained GeSn thin film samples ( t GeSn layer and 11% Sn composition.

  10. Molecular beam epitaxy grown GeSn p-i-n photodetectors integrated on Si

    Energy Technology Data Exchange (ETDEWEB)

    Werner, J., E-mail: werner@iht.uni-stuttgart.de; Oehme, M.; Schirmer, A.; Kasper, E.; Schulze, J.

    2012-02-01

    GeSn p-i-n photodetectors with a low Sn mole fraction made by molecular beam epitaxy on Si substrates show higher optical responsivities for wavelength {lambda} > 1400 nm compared with p-i-n photodetectors made from pure Ge. The Sn incorporation in Ge is done by a low temperature growth step in order to minimize Sn segregation. The Sn incorporation and the alloy content are investigated by {mu}-Raman spectroscopy and calibrated Secondary Ion Mass Spectrometry. The photodetectors are manufactured with sharp doping transitions and are realized as double mesa structures with diameters from 1.5 {mu}m up to 80 {mu}m. The optical measurements are carried out with a broadband super continuum laser from {lambda} = 1200 nm up to {lambda} = 1700 nm. At a wavelength of {lambda} = 1550 nm the optical responsivity of these vertical GeSn diodes is 0.1 A/W. In comparison with a pure Ge detector of the same geometrical dimensions the optical responsivity is increased by factor of three as a result of Sn caused band gap reduction.

  11. Dispersion of nonresonant third-order nonlinearities in GeSiSn ternary alloys

    Science.gov (United States)

    De Leonardis, Francesco; Troia, Benedetto; Soref, Richard A.; Passaro, Vittorio M. N.

    2016-01-01

    Silicon (Si), tin (Sn), and germanium (Ge) alloys have attracted research attention as direct band gap semiconductors with applications in electronics and optoelectronics. In particular, GeSn field effect transistors can exhibit very high performance in terms of power reduction and operating speed because of the high electron drift mobility, while the SiGeSn system can be constructed using CMOS-compatible techniques to realize lasers, LED, and photodetectors. The wide Si, Ge and Sn transparencies allow the use of binary and ternary alloys extended to mid-IR wavelengths, where nonlinearities can also be employed. However, neither theoretical or experimental predictions of nonlinear features in SiGeSn alloys are reported in the literature. For the first time, a rigorous and detailed physical investigation is presented to estimate the two photon absorption (TPA) coefficient and the Kerr refractive index for the SiGeSn alloy up to 12 μm. The TPA spectrum, the effective TPA wavelength cut-off, and the Kerr nonlinear refractive index have been determined as a function of alloy compositions. The promising results achieved can pave the way to the demonstration of on-chip nonlinear-based applications, including mid-IR spectrometer-on-a-chip, all-optical wavelength down/up-conversion, frequency comb generation, quantum-correlated photon-pair source generation and supercontinuum source creation, as well as Raman lasing. PMID:27622979

  12. Dispersion of nonresonant third-order nonlinearities in GeSiSn ternary alloys

    Science.gov (United States)

    de Leonardis, Francesco; Troia, Benedetto; Soref, Richard A.; Passaro, Vittorio M. N.

    2016-09-01

    Silicon (Si), tin (Sn), and germanium (Ge) alloys have attracted research attention as direct band gap semiconductors with applications in electronics and optoelectronics. In particular, GeSn field effect transistors can exhibit very high performance in terms of power reduction and operating speed because of the high electron drift mobility, while the SiGeSn system can be constructed using CMOS-compatible techniques to realize lasers, LED, and photodetectors. The wide Si, Ge and Sn transparencies allow the use of binary and ternary alloys extended to mid-IR wavelengths, where nonlinearities can also be employed. However, neither theoretical or experimental predictions of nonlinear features in SiGeSn alloys are reported in the literature. For the first time, a rigorous and detailed physical investigation is presented to estimate the two photon absorption (TPA) coefficient and the Kerr refractive index for the SiGeSn alloy up to 12 μm. The TPA spectrum, the effective TPA wavelength cut-off, and the Kerr nonlinear refractive index have been determined as a function of alloy compositions. The promising results achieved can pave the way to the demonstration of on-chip nonlinear-based applications, including mid-IR spectrometer-on-a-chip, all-optical wavelength down/up-conversion, frequency comb generation, quantum-correlated photon-pair source generation and supercontinuum source creation, as well as Raman lasing.

  13. SiGeSn Ternaries for Efficient Group IV Heterostructure Light Emitters.

    Science.gov (United States)

    von den Driesch, Nils; Stange, Daniela; Wirths, Stephan; Rainko, Denis; Povstugar, Ivan; Savenko, Aleksei; Breuer, Uwe; Geiger, Richard; Sigg, Hans; Ikonic, Zoran; Hartmann, Jean-Michel; Grützmacher, Detlev; Mantl, Siegfried; Buca, Dan

    2017-02-03

    SiGeSn ternaries are grown on Ge-buffered Si wafers incorporating Si or Sn contents of up to 15 at%. The ternaries exhibit layer thicknesses up to 600 nm, while maintaining a high crystalline quality. Tuning of stoichiometry and strain, as shown by means of absorption measurements, allows bandgap engineering in the short-wave infrared range of up to about 2.6 µm. Temperature-dependent photoluminescence experiments indicate ternaries near the indirect-to-direct bandgap transition, proving their potential for ternary-based light emitters in the aforementioned optical range. The ternaries' layer relaxation is also monitored to explore their use as strain-relaxed buffers, since they are of interest not only for light emitting diodes investigated in this paper but also for many other optoelectronic and electronic applications. In particular, the authors have epitaxially grown a GeSn/SiGeSn multiquantum well heterostructure, which employs SiGeSn as barrier material to efficiently confine carriers in GeSn wells. Strong room temperature light emission from fabricated light emitting diodes proves the high potential of this heterostructure approach.

  14. Strangeness enhancement at mid-rapidity in Pb-Pb collisions at 158 GeV/c

    CERN Document Server

    Andersen, E; Armenise, N; Bakke, H; Bán, J; Barberis, D; Beker, H; Beusch, Werner; Bloodworth, Ian J; Böhm, J; Caliandro, R; Campbell, M; Cantatore, E; Carrer, N; Catanesi, M G; Chesi, Enrico Guido; Dameri, M; Darbo, G; Diaczek, A; Di Bari, D; Di Liberto, S; Earl, B C; Elia, D; Evans, D; Fanebust, K; Fini, R A; Fontaine, J C; Ftácnik, J; Ghidini, B; Grella, G; Guida, M; Heijne, Erik H M; Helstrup, H; Holme, A K; Huss, D; Jacholkowski, A; Jones, G T; Jovanovic, P; Jusko, A; Kachelhoffer, T; Kinson, J B; Kirk, A; Klempt, W; Knudsen, H; Knudson, K P; Králik, I; Lenti, V; Lietava, R; Loconsole, R A; Løvhøiden, G; Lupták, M; Mack, V; Manzari, V; Martinengo, P; Mazzoni, M A; Meddi, F; Michalon, A; Michalon-Mentzer, M E; Middelkamp, P; Morando, M; Muciaccia, M T; Nappi, E; Navach, F; Norman, P I; Osculati, B; Pastircák, B; Pellegrini, F; Píska, K; Posa, F; Quercigh, Emanuele; Ricci, R A; Romano, G; Rosa, G; Rossi, L; Rotscheidt, Herbert; Safarík, K; Saladino, S; Salvo, C; Sándor, L; Segato, G F; Sené, M; Sené, R; Simone, S; Snoeys, W; Staroba, P; Szafran, S; Thompson, M; Thorsteinsen, T F; Tomasicchio, G; Torrieri, G D; Tveter, T S; Urbán, J; Venables, M; Villalobos Baillie, O; Virgili, T; Volte, A; Votruba, M F; Závada, P

    1999-01-01

    $K^{0}_{s}$, $\\Lambda$, $\\Xi$, $\\Omega$ and negative particle yields and transverse mass spectra have been measured at central rapidity in Pb-Pb and p-Pb collisions at 158 $A$ GeV/$c$. The yields in Pb-Pb interactions % are presented as a function of the collision centrality and compared with those obtained from p-Pb collisions. Strangeness enhancement in Pb-Pb relative to p-Pb collisions increases with the strangeness content of the particle. Going from p-Pb to Pb-Pb, the strange particle yields increase faster than linearly with the number of participants $N_{part}$ up to $N_{part} \\approx 100$, thereafter the increase becomes %linear with $N_{part}$. Yields are studied as a function of the number of nucleons participating in the collision $N_{part}$, which is estimated with the Glauber model. From p-Pb to Pb-Pb collisions the particle yields per participant increase substantially. The enhancement is more pronounced for multistrange particles, and exceeds an order of magnitude for the $\\Omega$. For a number...

  15. One-, two-, and three-particle distributions from 158A GeV/c central Pb+Pb collisions

    NARCIS (Netherlands)

    Aggarwal, MM; Angelis, ALS; Antonenko, [No Value; Arefiev, [No Value; Astakhov, [No Value; Avdeitchikov, [No Value; Awes, TC; Baba, PVKS; Badyal, SK; Bathe, S; Batiounia, B; Bernier, T; Bhalla, KB; Bhatia, VS; Blume, C; Bucher, D; Busching, H; Carlen, L; Chattopadhyay, S; Decowski, MP; Delagrange, H; Donni, P; Majumdar, MRD; El Chenawi, K; Enosawa, K; Fokin, S; Frolov, [No Value; Ganti, MS; Garpman, S; Gavrishchuk, O; Geurts, FJM; Ghosh, TK; Glasow, R; Guskov, B; Gustafsson, H.A.; Gutbrod, HH; Hrivnacova, [No Value; Ippolitov, M; Kalechofsky, H; Kamermans, R; Karadjev, K; Karpio, K; Kolb, BW; Kosarev, [No Value; Koutcheryaev, [No Value; Kugler, A; Kulinich, P; Kurata, M; Lebedev, A; Lohner, H; Mahapatra, DP; Manko, [No Value; Martin, M; Martinez, G; Maximov, A; Miake, Y; Mishra, GC; Mohanty, B; Mora, MJ; Morrison, D; Mukhanova, T; Mukhopadhyay, DS; Naef, H; Nandi, BK; Nayak, SK; Nayak, TK; Nianine, A; Nikitine, [No Value; Nikolaev, S; Nilsson, P; Nishimura, S; Nomokonov, P; Nystrand, J; Oskarsson, A; Otterlund, [No Value; Peitzmann, T; Peressounko, D; Petracek, [No Value; Plasil, F; Purschke, ML; Rak, J; Raniwala, R; Raniwala, S; Rao, NK; Reygers, K; Roland, G; Rosselet, L; Roufanov, [No Value; Rubio, JM; Sambyal, SS; Santo, R; Sato, S; Schlagheck, H; Schutz, Y; Shabratova, G; Shah, TH; Sibiriak, [No Value; Siemiarczuk, T; Silvermyr, D; Sinha, BC; Slavine, N; Soderstrom, K; Sood, G; Sorensen, SP; Stankus, P; Stefanek, G; Steinberg, P; Stenlund, E; Sumbera, M; Svensson, T; Tsvetkov, A.; Tykarski, L; v d Pijll, EC; v Eijndhoven, N; v Nieuwenhuizen, GJ; Vinogradov, A; Viyogi, YP; Vodopianov, A; Voros, S; Wyslouch, B; Young, GR

    2003-01-01

    Several hadronic observables have been studied in central 158A GeV Pb+Pb collisions using data measured by the WA98 experiment at CERN: single pi(-) and K- production, as well as two- and three-pion interferometry. The Wiedemann-Heinz hydrodynamical model has been fitted to the pion spectrum, giving

  16. Event-by-event charged-neutral fluctuations in Pb plus Pb collisions at 158 A GeV

    NARCIS (Netherlands)

    Aggarwal, M. M.; Ahammed, Z.; Angelis, A. L. S.; Antonenko, V.; Arefiev, V.; Astakhov, V.; Avdeitchikov, V.; Awes, T. C.; Baba, P. V. K. S.; Badyal, S. K.; Bathe, S.; Batiounia, B.; Bernier, T.; Bhalla, K. B.; Bhatia, V. S.; Blume, C.; Bucher, D.; Buesching, H.; Carlen, L.; Chattopadhyay, S.; Decowski, M. P.; Delagrange, H.; Donni, P.; Majumdar, M. R. Dutta; El Chenawi, K.; Dubey, A. K.; Enosawa, K.; Fokin, S.; Frolov, V.; Ganti, M. S.; Garpman, S.; Gavrishchuk, O.; Geurts, F. J. M.; Ghosh, T. K.; Glasow, R.; Gupta, R.; Guskov, B.; Gustafsson, H.A.; Gutbrod, H. H.; Hrivnacova, I.; Ippolitov, M.; Kalechofsky, H.; Kamermans, R.; Karadjev, K.; Karpios, K.; Kolb, B. W.; Kosarev, I.; Koutcheryaev, I.; Kugler, A.; Kulinich, P.; Kurata, M.; Lebedev, A.; Liu, H.; Löhner, H.; Luquin, L.; Mahapatra, D. P.; Manko, V.; Martin, M.; Martinez, G.; Maximov, A.; Miake, Y.; Mishra, G. C.; Mohanty, B.; Mora, M. -J.; Morrison, D.; Moukhanova, T.; Mukhopadhyay, D. S.; Naef, H.; Nandi, B. K.; Nayak, S. K.; Nayak, T. K.; Nianine, A.; Nikitine, V.; Nikolaev, S.; Nilsson, P.; Nishimura, S.; Nomokonov, P.; Nystrand, J.; Oskarsson, A.; Otterlund, I.; Pavliouk, S.; Peitzmann, T.; Peressounko, D.; Petracek, V.; Pinanaud, W.; Plasil, F.; Purschke, M. L.; Rak, J.; Raniwala, R.; Raniwala, S.; Rao, N. K.; Retiere, F.; Reygers, K.; Roland, G.; Rosselet, L.; Roufanov, I.; Roy, C.; Rubio, J. M.; Sambyal, S. S.; Santo, R.; Sato, S.; Schlagheck, H.; Schmidt, H. -R.; Schutz, Y.; Shabratova, G.; Shah, T. H.; Sibiriak, I.; Siemiarczuk, T.; Silvermyr, D.; Sinha, B. C.; Slavine, N.; Soderstrom, K.; Sood, G.; Sorensen, S. P.; Stankus, P.; Stefanek, G.; Steinberg, P.; Stenlund, E.; Sumbera, M.; Svensson, T.; Tsvetkov, A.; Tykarski, L.; Pijll, E. C. V. D.; Eijndhoven, N. V.; Nieuwenhuizen, G. J. V.; Vinogradov, A.; Viyogi, Y. P.; Vodopianov, A.; Voeroes, S.; Wyslouch, B.; Young, G. R.

    2011-01-01

    Charged particles and photons have been measured in central Pb + Pb collisions at 158 A GeV in a common (eta-phi)-phase space region in the WA98 experiment at the CERN SPS. The measured distributions have been analyzed to quantify the frequency with which phase space regions of varying sizes have

  17. Centrality dependence of charged-neutral particle fluctuations in 158A (GeVPb)-Pb-208+Pb-208 collisions

    NARCIS (Netherlands)

    Aggarwal, MM; Ahammed, Z; Angelis, ALS; Antonenko, [No Value; Arefiev, [No Value; Astakhov, [No Value; Avdeitchikov, [No Value; Awes, TC; Baba, PVKS; Badyal, SK; Bathe, S; Batiounia, B; Bernier, T; Bhalla, KB; Bhatia, VS; Blume, C; Bucher, D; Busching, H; Carlen, L; Chattopadhyay, S; Decowski, MP; Delagrange, H; Donni, P; Majumdar, MRD; El Chenawi, K; Dubey, AK; Enosawa, K; Fokin, S; Frolov, [No Value; Ganti, MS; Garpman, S; Gavrishchuk, O; Geurts, FJM; Ghosh, TK; Glasow, R; Guskov, B; Gustafsson, H.A.; Gutbrod, HH; Hrivnacova, [No Value; Ippolitov, M; Kalechofsky, H; Karadjev, K; Karpio, K; Kolb, BW; Kosarev, [No Value; Koutcheryaev, [No Value; Kugler, A; Kulinich, P; Kurata, M; Lebedev, A; Lohner, H; Luquin, L; Mahapatra, DP; Manko, [No Value; Martin, M; Martinez, G; Maximov, A; Miake, Y; Mishra, GC; Mohanty, B; Mora, MJ; Morrison, D; Mukhanova, T; Mukhopadhyay, DS; Naef, H; Nandi, BK; Nayak, SK; Nayak, TK; Nianine, A; Nikitine, [No Value; Nikolaev, S; Nilsson, P; Nishimura, S; Nomokonov, P; Nystrand, J; Oskarsson, A; Otterlund, [No Value; Peitzmann, T; Peressounko, D; Petracek, [No Value; Pinganaud, W; Plasil, F; Purschke, ML; Rak, J; Raniwala, R; Raniwala, S; Rao, NK; Retiere, F; Reygers, K; Roland, G; Rosselet, L; Roufanov, [No Value; Roy, C; Rubio, JM; Sambyal, SS; Santo, R; Sato, S; Schlagheck, H; Schutz, Y; Shabratova, G; Shah, TH; Sibiriak, [No Value; Siemiarczuk, T; Silvermyr, D; Sinha, BC; Slavine, N; Soderstrom, K; Sood, G; Sorensen, SP; Stankus, P; Stefanek, G; Steinberg, P; Stenlund, E; Sumbera, M; Svensson, T; Tsvetkov, A.; Tykarski, L; von der Pijll, EC; von Eijndhoven, N; von Nieuwenhuizen, GJ; Vinogradov, A; Viyogi, YP; Vodopianov, A; Voros, S; Wyslouch, B; Young, GR

    Results on the study of localized fluctuations in the multiplicity of charged particles and photons produced in 158A GeV/c Pb+Pb collisions are presented for varying centralities. The charged versus neutral particle multiplicity correlations in common phase space regions of varying azimuthal sizes

  18. First look at NA52 data on Pb-Pb interactions at 158 A ṡ GeV/c

    Science.gov (United States)

    Dittus, F.; Appelquist, G.; Baglin, C.; Beringer, J.; Borer, K.; Bohm, C.; Bussière, A.; Elsener, K.; Frei, D.; Gorodetzky, Ph.; Guillaud, J. P.; Hugentobler, E.; Klingenberg, R.; Lindén, T.; Lohmann, K. D.; Moser, U.; Pal, T.; Pretzl, K.; Schacher, J.; Selldén, B.; Stoffel, F.; Tuominiemi, J.; Zhang, Q. P.

    1995-07-01

    We have searched for strange matter particles, so-called strangelets, in Pb-Pb interactions at plab=157.7 GeV/c per nucleon. The NA52 apparatus is also ideally suited to measure production yields and rapidity distribution of π±, K±, p, p¯, d, d¯, ... near 00 production angle. Some preliminary results are shown.

  19. Ternary GeSiSn alloys: New opportunities for strain and band gap engineering using group-IV semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    D' Costa, V.R. [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States); Fang, Y.-Y.; Tolle, J.; Kouvetakis, J. [Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604 (United States); Menendez, J. [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States)

    2010-02-26

    Ternary GeSiSn alloys have been recently demonstrated on Ge- and GeSn-buffered Si substrates. These alloys, with a two-dimensional compositional space, make it possible to decouple lattice constant and electronic structure for the first time in a group-IV system. This paper reviews the basic properties of the GeSiSn alloy, presents some new results on its optical properties, and discusses the approach that has been followed to model heterostructures containing GeSiSn layers for applications in modulators, quantum cascade lasers, and photovoltaics.

  20. In-situ Ga doping of fully strained Ge{sub 1-x}Sn{sub x} heteroepitaxial layers grown on Ge(001) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Shimura, Y., E-mail: ysimura@alice.xtal.nagoya-u.ac.jp [Graduate School of Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan); Research Fellow of the Japan Society for the Promotion of Science (Japan); Takeuchi, S.; Nakatsuka, O. [Graduate School of Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan); Vincent, B.; Gencarelli, F.; Clarysse, T.; Vandervorst, W.; Caymax, M.; Loo, R. [imec, Kapeldreef 75, B-3001 Leuven (Belgium); Jensen, A. [CAPRES A/S, Scion-DTU, Building 373, DK-2800, Kgs. Lyngby (Denmark); Petersen, D.H. [Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345B, DK-2800 Kgs. Lyngby (Denmark); Zaima, S. [Graduate School of Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan)

    2012-02-01

    We have investigated the Ga and Sn content dependence of the crystallinity and electrical properties of Ga-doped Ge{sub 1-x}Sn{sub x} layers that are heteroepitaxially grown on Ge(001) substrates. The doping of Ga to levels as high as the solubility limit of Ga at the growth temperature leads to the introduction of dislocations, due to the increase in the strain of the Ge{sub 1-x}Sn{sub x} layers. We achieved the growth of a fully strained Ge{sub 0.922}Sn{sub 0.078} layer on Ge with a Ga concentration of 5.5 Multiplication-Sign 10{sup 19} /cm{sup 3} without any dislocations and stacking faults. The resistivity of the Ga-doped Ge{sub 1-x}Sn{sub x} layer decreased as the Sn content was increased. This decrease was due to an increase in the carrier concentration, with an increase in the activation level of Ga atoms in the Ge{sub 1-x}Sn{sub x} epitaxial layers being induced by the introduction of Sn. As a result, we found that the resistivity for the Ge{sub 0.950}Sn{sub 0.050} layer annealed at 600 Degree-Sign C for 1 min is 3.6 times less than that of the Ga-doped Ge/Ge sample. - Highlights: Black-Right-Pointing-Pointer Heavy Ga-doping into fully strained GeSn layers without the introduction of dislocations Black-Right-Pointing-Pointer The uniform Ga depth profile allowed the introduction of Sn Black-Right-Pointing-Pointer The decrease in resistivity with an increase in the activation level of Ga was caused by the introduction of Sn.

  1. Optical, thermal and phase transition studies in Sn1–GeTe

    Indian Academy of Sciences (India)

    M Sivabharathy; N Sankar; R Saravanan; K Ramachandran

    2005-12-01

    The optical and thermal properties of the mixed semiconducting alloy, Sn1–GeTe, is studied by photo acoustics, for various Ge concentrations and phase transition for a particular concentration is also studied by the same method. The results are compared with the available literature values and discussed.

  2. Oxidation and Reduction of Liquid SnPb (60/40) under Ambient and Vacuum Conditions

    DEFF Research Database (Denmark)

    Kuhmann, Jochen Friedrich; Maly, K.; Preuss, A.;

    1998-01-01

    One of the most straightforward approaches to fluxless solder bonding is using vacuum conditions to prevent further oxidation and, where needed, to reduce solder oxides by the use of molecular hydrogen (H-2).(1-3) This study On oxidation and reduction of solder oxides on SnPb (60/40) is aimed...... to provide a better understanding for fluxless solder bonding applications under controlled atmospheric conditions; By means of scanning Auger spectroscopy it is shown, that growth of oxide films on metallic SnPb above the eutectic temperature can be significantly reduced by decreasing the O-2 partial...... at 200 and 250 degrees C is crystalline SnO. For sample preparation, the reduction of the native oxide on eutectic SnPb was carried out successfully using low temperature (250 degrees C) and short heating cycles (2 min). The effectiveness of H-2 to reduce SnO2 at typical soldering parameters (240 degrees...

  3. Weak Topological Insulators in PbTe/SnTe superlattice

    Science.gov (United States)

    Yang, Gang; Liu, Junwei; Fu, Liang; Duan, Wenhui; Liu, Chaoxing

    2014-03-01

    It is desirable to realize topological phases in artificial structures by engineering electronic band structures. In this paper, we investigate (PbTe)m(SnTe)2n-m superlattices along the [001] direction and find a robust weak topological insulator phase for a large variety of layer numbers m and 2 n - m . We confirm this topologically non-trivial phase by calculating Z2 topological invariants and topological surface states based on the first-principles calculations. We show that the folding of Brillouin zone due to the superlattice structure plays an essential role in inducing topologically non-trivial phases in this system. This mechanism can be generalized to other systems in which band inversion occurs at multiple momenta, and gives us a brand-new way to engineer topological materials in artificial structures. We acknowledge support from the Ministry of Science and Technology of China and the National Natural Science Foundation of China. LF is supported by the DOE Office of Basic Energy Sciences.

  4. Negative differential resistance in direct bandgap GeSn p-i-n structures

    Science.gov (United States)

    Schulte-Braucks, C.; Stange, D.; von den Driesch, N.; Blaeser, S.; Ikonic, Z.; Hartmann, J. M.; Mantl, S.; Buca, D.

    2015-07-01

    Certain GeSn alloys are group IV direct bandgap semiconductors with prospects for electrical and optoelectronical applications. In this letter, we report on the temperature dependence of the electrical characteristics of high Sn-content Ge 0.89 Sn 0.11 p-i-n diodes. NiGeSn contacts were used to minimize the access resistance and ensure compatibility with silicon technology. The major emphasis is placed on the negative differential resistance in which peak to valley current ratios up to 2.3 were obtained. TCAD simulations were performed to identify the origin of the various current contributions, providing evidence for direct band to band tunneling and trap assisted tunneling.

  5. GeSn-on-Si normal incidence photodetectors with bandwidths more than 40 GHz.

    Science.gov (United States)

    Oehme, Michael; Kostecki, Konrad; Ye, Kaiheng; Bechler, Stefan; Ulbricht, Kai; Schmid, Marc; Kaschel, Mathias; Gollhofer, Martin; Körner, Roman; Zhang, Wogong; Kasper, Erich; Schulze, Jörg

    2014-01-13

    GeSn (Sn content up to 4.2%) photodiodes with vertical pin structures were grown on thin Ge virtual substrates on Si by a low temperature (160 °C) molecular beam epitaxy. Vertical detectors were fabricated by a double mesa process with mesa radii between 5 µm and 80 µm. The nominal intrinsic absorber contains carrier densities from below 1 · 10(16) cm(-3) to 1 · 10(17) cm(-3) for Ge reference detectors and GeSn detectors with 4.2% Sn, respectively. The photodetectors were investigated with electrical and optoelectrical methods from direct current up to high frequencies (40 GHz). For a laser wavelength of 1550 nm an increasing of the optical responsivities (84 mA/W -218 mA/W) for vertical incidence detectors with thin (300 nm) absorbers as function of the Sn content were found. Most important from an application perspective all detectors had bandwidth above 40 GHz at enough reverse voltage which increased from zero to -5 V within the given Sn range. Increasing carrier densities (up to 1 · 10(17) cm(-3)) with Sn contents caused the depletion of the nominal intrinsic absorber at increasing reverse voltages.

  6. Impact of thickness on the structural properties of high tin content GeSn layers

    Science.gov (United States)

    Aubin, J.; Hartmann, J. M.; Gassenq, A.; Milord, L.; Pauc, N.; Reboud, V.; Calvo, V.

    2017-09-01

    We have grown various thicknesses of GeSn layers in a 200 mm industrial Reduced Pressure - Chemical Vapor Deposition cluster tool using digermane (Ge2H6) and tin tetrachloride (SnCl4). The growth pressure (100 Torr) and the F(Ge2H6)/F(SnCl4) mass-flow ratio were kept constant, and incorporation of tin in the range of 10-15% was achieved with a reduction in temperature: 325 °C for 10% to 301 °C for 15% of Sn. The layers were grown on 2.5 μm thick Ge Strain Relaxed Buffers, themselves on Si(0 0 1) substrates. We used X-ray Diffraction, Atomic Force Microscopy, Raman spectroscopy and Scanning Electron Microscopy to measure the Sn concentration, the strain state, the surface roughness and thickness as a function of growth duration. A dramatic degradation of the film was seen when the Sn concentration and layer thickness were too high resulting in rough/milky surfaces and significant Sn segregation.

  7. Creep Behavior of Lead-Free Sn-Ag-Cu + Ni-Ge Solder Alloys

    Science.gov (United States)

    Hidaka, N.; Watanabe, H.; Yoshiba, M.

    2009-05-01

    We developed a new lead-free solder alloy, an Sn-Ag-Cu base to which a small amount of Ni and Ge is added, to improve the mechanical properties of solder alloys. We examined creep deformation in bulk and through-hole (TH) form for two lead-free solder alloys, Sn-3.5Ag-0.5Cu-Ni-Ge and Sn-3.0Ag-0.5Cu, at elevated temperatures, finding that the creep rupture life of the Sn-3.5Ag-0.5Cu-Ni-Ge solder alloy was over three times better than that of the Sn-3.0Ag-0.5Cu solder at 398 K. Adding Ni to the solder appears to make microstructural development finer and more uniform. The Ni added to the solder readily combined with Cu to form stable intermetallic compounds of (Cu, Ni)6Sn5 capable of improving the creep behavior of solder alloys. Moreover, microstructural characterization based on transmission electron microscopy analyses observing creep behavior in detail showed that such particles in the Sn-3.5Ag-0.5Cu-Ni-Ge solder alloy prevent dislocation and movement.

  8. Photocurrent Properties of Undoped and Pb-Doped SnS Nanostructures Grown Using Electrodeposition Method

    Science.gov (United States)

    Niknia, Farhad; Jamali-Sheini, Farid; Yousefi, Ramin

    2015-12-01

    Nanostructured Pb-doped SnS thin films were deposited onto fluorine-doped tin oxide-coated glass substrates by electrochemical deposition. The films were characterized using different techniques to study their structural, morphological, and optical properties. The x-ray diffraction analysis indicated that the films were polycrystalline in nature and had an orthorhombic crystal structure. Scanning electron microscopy studies showed that the Pb dopant could significantly change the morphology of the nanostructures. Energy dispersive spectroscopy showed different concentrations of Pb for different morphologies. Optical measurements suggested a red shift for the band gap values from 1.46 eV to 1.40 eV with an increase in the Pb concentration. Finally, the photocurrent responses of the nanostructures were studied. The results revealed that Pb-doped SnS nanostructures exhibited better response than the undoped SnS nanostructures.

  9. Hydrometallation Group 4 (Si, Sn, Ge, and Pb)

    OpenAIRE

    Dobbs, A.P.; Chio, F.K.I.

    2014-01-01

    This chapter will discuss the addition reactions of the hydrides of the Group IV elements to carbon–carbon double and triple bonds, namely hydrosilylation, hydrostannylation, hydrogermylation, and hydroplumbylation reactions of alkynes and alkenes.\\ud Although there is no corresponding chapter in the first edition of Comprehensive Organic Synthesis, the material presented here will follow on from Chapters 3.9 and 3.12 and the reader is referred back to these.

  10. An investigation of the antinuclei and nuclei production mechanism in Pb + Pb collisions at 158-A-GeV

    Energy Technology Data Exchange (ETDEWEB)

    Arsenescu, R [Laboratorium fuer Hochenergiephysik, Universitaet Bern, Sidlerstrasse 5, 3012-Bern (Switzerland); Baglin, C [CNRS-IN2P3, LAPP Annecy, F-74941 Annecy-le-Vieux (France); Beck, H P [Laboratorium fuer Hochenergiephysik, Universitaet Bern, Sidlerstrasse 5, 3012-Bern (Switzerland); Borer, K [Laboratorium fuer Hochenergiephysik, Universitaet Bern, Sidlerstrasse 5, 3012-Bern (Switzerland); Bussiere, A [CNRS-IN2P3, LAPP Annecy, F-74941 Annecy-le-Vieux (France); Elsener, K [CERN, SL Division, CH-1211 Geneva 23 (Switzerland); Gorodetzky, Ph [PCC - College de France, 11 Place Marcellin Berthelod, 75005 Paris, France (France); Guillaud, J P [CNRS-IN2P3, LAPP Annecy, F-74941 Annecy-le-Vieux (France); Kabana, S [Laboratorium fuer Hochenergiephysik, Universitaet Bern, Sidlerstrasse 5, 3012-Bern (Switzerland); Klingenberg, R [Laboratorium fuer Hochenergiephysik, Universitaet Bern, Sidlerstrasse 5, 3012-Bern (Switzerland); Lehmann, G [Laboratorium fuer Hochenergiephysik, Universitaet Bern, Sidlerstrasse 5, 3012-Bern (Switzerland); Linden, T [Helsinki Institute of Physics, PO Box 9, FIN-00014 Helsinki (Finland); Lohmann, K D [CERN, SL Division, CH-1211 Geneva 23 (Switzerland); Mommsen, R [Laboratorium fuer Hochenergiephysik, Universitaet Bern, Sidlerstrasse 5, 3012-Bern (Switzerland); Moser, U [Laboratorium fuer Hochenergiephysik, Universitaet Bern, Sidlerstrasse 5, 3012-Bern (Switzerland); Pretzl, K [Laboratorium fuer Hochenergiephysik, Universitaet Bern, Sidlerstrasse 5, 3012-Bern (Switzerland); Schacher, J [Laboratorium fuer Hochenergiephysik, Universitaet Bern, Sidlerstrasse 5, 3012-Bern (Switzerland); Spiwoks, R [Laboratorium fuer Hochenergiephysik, Universitaet Bern, Sidlerstrasse 5, 3012-Bern (Switzerland); Tuominiemi, J [Helsinki Institute of Physics, PO Box 9, FIN-00014 Helsinki (Finland); Weber, M [Laboratorium fuer Hochenergiephysik, Universitaet Bern, Sidlerstrasse 5, 3012-Bern (Switzerland)

    2003-11-01

    We investigate the production mechanisms of p, d, t, {sup 3}He, {sup 4}He, {sup 6}Li, pbar,dbar and {sup 3}Hebar in Pb+Pb collisions at 158-A-GeV measured near zero transverse momentum with the NA52 experiment at the CERN SPS. We find evidence that nuclei and antinuclei in Pb+Pb collisions are mainly produced via the coalescence mechanism out of a thermalized source of hadrons, at a time close to the thermal freeze-out of hadrons corresponding to a temperature of {approx}120-MeV.

  11. An investigation of the antinuclei and nuclei production mechanism in Pb + Pb collisions at 158 A GeV

    Science.gov (United States)

    Arsenescu, R.; Baglin, C.; Beck, H. P.; Borer, K.; Bussière, A.; Elsener, K.; Gorodetzky, Ph; Guillaud, J. P.; Kabana, S.; Klingenberg, R.; Lehmann, G.; Lindén, T.; Lohmann, K. D.; Mommsen, R.; Moser, U.; Pretzl, K.; Schacher, J.; Spiwoks, R.; Tuominiemi, J.; Weber, M.

    2003-11-01

    We investigate the production mechanisms of p, d, t, 3He, 4He, 6Li, \\overline {\\mathrm {p}} , \\overline {\\mathrm {d}} and \\overline {^3{\\mathrm {He}}} in Pb+Pb collisions at 158 A GeV measured near zero transverse momentum with the NA52 experiment at the CERN SPS. We find evidence that nuclei and antinuclei in Pb+Pb collisions are mainly produced via the coalescence mechanism out of a thermalized source of hadrons, at a time close to the thermal freeze-out of hadrons corresponding to a temperature of ~120 MeV.

  12. Anodic Layer of Pb-Ca-Sn-Ce Alloy for Maintenance-Free Lead/Acid Batteries

    Institute of Scientific and Technical Information of China (English)

    Li Dangguo; Zhou Genshu; Lin Guanfa; Zheng Maosheng

    2005-01-01

    The anodic films of novel Pb-Ca-Sn-Ce alloy, traditional Pb-Ca-Sn and Pb-Sb alloys formed in sulfuric solution at anodic +0.9 V potential corrosion for 6 h were investigated by means of XPS, XRD methods and AC impedance measurement. The results show that the growth of Pb(Ⅱ) oxide on the new Pb-Ca-Sn-Ce alloy surface is inhibited. The AC impedance measurement shows that resistance of the corrosion layer of novel Pb-Ca-Sn-Ce alloy decreases. It is found that the novel Pb-Ca-Sn-Ce alloy can encourage the development of PbO2 in the scale, and enhance the conductivity of the anodic scale. Hence the deep recycling properties of the battery can be expected better.

  13. High quality, giant crystalline-Ge stripes on insulating substrate by rapid-thermal-annealing of Sn-doped amorphous-Ge in solid-liquid coexisting region

    Directory of Open Access Journals (Sweden)

    Ryo Matsumura

    2015-06-01

    Full Text Available Formation of large-grain (≥30 μm Ge crystals on insulating substrates is strongly desired to achieve high-speed thin-film transistors. For this purpose, we propose the methods of Sn-doping into amorphous-Ge combined with rapid-thermal-annealing (RTA in the solid-liquid coexisting temperature region for the Ge-Sn alloy system. The densities of micro-crystal-nuclei formed in this temperature region become low by tuning the RTA temperature close to the liquidus curve, which enhances the lateral growth of GeSn. Thanks to the very small segregation coefficient of Sn, almost all Sn atoms segregate toward edges of the stripes during growth. Agglomeration of GeSn degrades the surface morphologies; however, it is significantly improved by lowering the initial Sn concentration. As a result, pure Ge with large crystal grains (∼40 μm with smooth surface are obtained by optimizing the initial Sn concentration as low as 3 ∼ 5%. Lateral growth lengths are further increased through decreasing the number of nuclei in stripes by narrowing stripe width. In this way, high-crystallinity giant Ge crystals (∼200 μm are obtained for the stripe width of 3 μm. This “Si-seed free” technique for formation of large-grain pure Ge crystals is very useful to realize high-performance thin-film devices on insulator.

  14. High quality, giant crystalline-Ge stripes on insulating substrate by rapid-thermal-annealing of Sn-doped amorphous-Ge in solid-liquid coexisting region

    Science.gov (United States)

    Matsumura, Ryo; Kai, Yuki; Chikita, Hironori; Sadoh, Taizoh; Miyao, Masanobu

    2015-06-01

    Formation of large-grain (≥30 μm) Ge crystals on insulating substrates is strongly desired to achieve high-speed thin-film transistors. For this purpose, we propose the methods of Sn-doping into amorphous-Ge combined with rapid-thermal-annealing (RTA) in the solid-liquid coexisting temperature region for the Ge-Sn alloy system. The densities of micro-crystal-nuclei formed in this temperature region become low by tuning the RTA temperature close to the liquidus curve, which enhances the lateral growth of GeSn. Thanks to the very small segregation coefficient of Sn, almost all Sn atoms segregate toward edges of the stripes during growth. Agglomeration of GeSn degrades the surface morphologies; however, it is significantly improved by lowering the initial Sn concentration. As a result, pure Ge with large crystal grains (˜40 μm) with smooth surface are obtained by optimizing the initial Sn concentration as low as 3 ˜ 5%. Lateral growth lengths are further increased through decreasing the number of nuclei in stripes by narrowing stripe width. In this way, high-crystallinity giant Ge crystals (˜200 μm) are obtained for the stripe width of 3 μm. This "Si-seed free" technique for formation of large-grain pure Ge crystals is very useful to realize high-performance thin-film devices on insulator.

  15. Enhancement of carrier mobility in thin Ge layer by Sn co-doping

    Science.gov (United States)

    Prucnal, S.; Liu, F.; Berencén, Y.; Vines, L.; Bischoff, L.; Grenzer, J.; Andric, S.; Tiagulskyi, S.; Pyszniak, K.; Turek, M.; Drozdziel, A.; Helm, M.; Zhou, S.; Skorupa, W.

    2016-10-01

    We present the development, optimization and fabrication of high carrier mobility materials based on GeOI wafers co-doped with Sn and P. The Ge thin films were fabricated using plasma-enhanced chemical vapour deposition followed by ion implantation and explosive solid phase epitaxy, which is induced by millisecond flash lamp annealing. The influence of the recrystallization mechanism and co-doping of Sn on the carrier distribution and carrier mobility both in n-type and p-type GeOI wafers is discussed in detail. This finding significantly contributes to the state-of-the-art of high carrier mobility-GeOI wafers since the results are comparable with GeOI commercial wafers fabricated by epitaxial layer transfer or SmartCut technology.

  16. Formation mechanism of primary phases and eutectic structures within undercooled Pb-Sb-Sn ternary alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The solidification characteristics of three types of Pb-Sb-Sn ternary alloys with different primary phases were studied under substantial undercooling conditions. The experimental results show that primary (Pb) and SbSn phases grow in the dendritic mode, whereas primary (Sb) phase exhibits faceted growth in the form of polygonal blocks and long strips. (Pb) solid solution phase displays strong affinity with SbSn intermetallic compound so that they produce various morphologies of pseudobinary eutectics, but it can only grow in the divorced eutectic mode together with (Sb) phase. Although (Sb) solid solution phase and SbSn intermetallic com- pound may grow cooperatively within ternary eutectic microstructures, they sel- dom form pseudobinary eutectics independently. The (Pb)+(Sb)+SbSn ternary eutectic structure usually shows lamellar morphology, but appears as anomalous eutectic when its volume fraction becomes small. EDS analyses reveal that all of the three primary (Pb), (Sb) and SbSn phases exhibit conspicuous solute trapping effect during rapid solidification, which results in the remarkable extension of sol- ute solubility.

  17. Formation mechanism of primary phases and eutectic structures within undercooled Pb-Sb-Sn ternary alloys

    Institute of Scientific and Technical Information of China (English)

    WANG WeiLi; DAI FuPing; WEI BingBo

    2007-01-01

    The solidification characteristics of three types of Pb-Sb-Sn ternary alloys with different primary phases were studied under substantial undercooling conditions. The experimental results show that primary (Pb) and SbSn phases grow in the dendritic mode, whereas primary (Sb) phase exhibits faceted growth in the form of polygonal blocks and long strips. (Pb) solid solution phase displays strong affinity with SbSn intermetallic compound so that they produce various morphologies of pseudobinary eutectics, but it can only grow in the divorced eutectic mode together with (Sb) phase. Although (Sb) solid solution phase and SbSn intermetallic compound may grow cooperatively within ternary eutectic microstructures, they seldom form pseudobinary eutectics independently. The (Pb)+(Sb)+SbSn ternary eutectic structure usually shows lamellar morphology, but appears as anomalous eutectic when its volume fraction becomes small. EDS analyses reveal that all of the three primary (Pb), (Sb) and SbSn phases exhibit conspicuous solute trapping effect during rapid solidification, which results in the remarkable extension of solute solubility.

  18. Synthesis and optical properties of Sn-rich Ge{sub 1–x–y}Si{sub x}Sn{sub y} materials and devices

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Chi [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States); Beeler, Richard T. [Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604 (United States); Jiang, Liying; Gallagher, James D.; Favaro, Ruben [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States); Menéndez, José, E-mail: jose.menendez@asu.edu [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States); Kouvetakis, John [Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604 (United States)

    2014-04-30

    Sn-rich Ge{sub 1−x−y}Si{sub x}Sn{sub y} alloys (y > x) have been deposited on Si(100) using recently developed growth processes aimed at achieving the material quality and compositions required to investigate their optical emission properties. The samples are produced using two different methods, each providing optimal quality material within distinct composition ranges of low (2–4% Sn and 1–2% Si) and high (5–10% Sn and 3–4% Si) Sn and Si contents, allowing a comprehensive investigation of their optical response over the targeted 2–10% Sn range. The growth processes are based on ultra-low temperature (310–260 °C) Ultra-High Vacuum Chemical Vapor Deposition and Gas-Source Molecular Beam Epitaxy techniques using stoichiometric reactions of highly reactive hydride sources, including Ge{sub 4}H{sub 10}, Ge{sub 3}H{sub 8}, Si{sub 4}H{sub 10} and SnD{sub 4}. Under these conditions the depositions produce monocrystalline layers exhibiting high quality microstructure, flat surfaces, and large thicknesses of 450–600 nm. The latter provide a significantly high volume-fraction of GeSiSn active component away from the inherently defective GeSiSn/Si(100) interface, leading to dramatically improved optical quality materials which are found to exhibit a tunable direct-gap photoluminescence below 1550 nm. Photocurrent measurements of prototype photodiodes were also used to corroborate and further explore the dependence of the direct gap on the Si/Sn concentration. Collectively the results indicate that thermally superior Ge{sub 1−x−y}Si{sub x}Sn{sub y} alloys may offer an alternative technology to Ge{sub 1−y}Sn{sub y} analogs for long-wavelength applications beyond the absorption edge of elemental Ge. - Highlights: • Ge{sub 1−x−y}Si{sub x}Sn{sub y} alloys with y > x have been synthesized. • Photoluminescence shows that the alloys have direct band gaps below that of Ge. • GeSiSn may represent an alternative to GeSn for long

  19. Charged pion production in fixed-target Pb + Pb collisions at 158 GeV/nucleon

    Science.gov (United States)

    NA52 Collaboration; Ambrosini, G.; Arsenescu, R.; Baglin, C.; Beringer, J.; Bohm, C.; Borer, K.; Bussière, A.; Dittus, F.; Elsener, K.; Gorodetzky, Ph; Guillaud, J. P.; Hess, P.; Kabana, S.; Klingenberg, R.; Lohmann, K. D.; Mommsen, R.; Moser, U.; Pretzl, K.; Schacher, J.; Selldén, B.; Stoffel, F.; Weber, M.; Zhang, Q. P.

    1999-12-01

    Changes in pion production as a function of the impact parameter of the collision or the incident energy, may reveal characteristics of a possible first-order phase transition from nuclear to quark matter, as predicted by lattice quantum chromodynamics. In this paper we investigate charged pion production in Pb+Pb collisions at 158 GeV/nucleon near 0° production angle and at forward rapidity (4.3≤ y≤ 6.3). The centrality dependence of pion production is shown in the impact parameter range ~ 2-12 fm at the rapidities y = 5.7 and 6.3. An enhancement in the π-π+ ratio has been measured near beam rapidity, indicating Coulomb interaction of charged pions with the spectator protons. The charged pion yield per nucleon participating in the collision (Np) at y = 5.7 increases faster than linearly with Np, up to Np~100 and then it saturates, while at y = 6.3 it does not exhibit any sudden change as a function of Np.

  20. A new measurement of $J/\\psi$ suppression in Pb-Pb collisions at 158 GeV per nucleon

    CERN Document Server

    Alessandro, Bruno; Arnaldi, R; Atayan, M; Beolè, S; Boldea, V; Bordalo, P; Borges, G; Castanier, G; Castor, J; Chaurand, B; Cheynis, B; Chiavassa, E; Cicalò, C; Comets, M P; Constantinescu, S; Cortesc, P; De Falco, A; De Marco, N; Dellacasa, G; Devaux, A; Dita, S; Drapier, O; Fargeix, J; Force, P; Gallio, M; Gerschel, C; Giubellino, P; Golubeva, M B; Gonin, M; Grigorian, A A; Grigorian, S; Guber, F F; Guichard, A; Gulkanian, H R; Idzik, M; Jouan, D; Karavicheva, T L; Kluberg, L; Kurepin, A B; Le Bornec, Y; Lourenço, C; MacCormick, M; Macciotta, P; Marzari-Chiesa, A; Masera, M; Masoni, A; Monteno, M; Musso, A; Petiau, P; Piccotti, P; Pizzi, J R; Prino, F; Puddu, G; Quintans, C; Ramello, L; Ramos, S; Riccati, L; Romana, A; Santos, H; Saturnini, P; Scomparin, E; Serci, S; Shahoyan, R; Sigaudo, F; Sitta, M; Sonderegger, P; Tarrago, X; Topilskaya, N S; Usai, G L; Vercellin, E; Villatte, L; Willis, N; Wu, T

    2005-01-01

    We present a new measurement of J/psi production in Pb-Pb collisions at 158 GeV/nucleon, from the data sample collected in year 2000 by the NA50 Collaboration, under improved experimental conditions with respect to previous years. With the target system placed in vacuum, the setup was better adapted to study, in particular, the most peripheral nuclear collisions with unprecedented accuracy. The analysis of this data sample shows that the (J/ psi )/Drell-Yan cross-sections ratio measured in the most peripheral Pb-Pb interactions is in good agreement with the nuclear absorption pattern extrapolated from the studies of proton-nucleus collisions. Furthermore, this new measurement confirms our previous observation that the (J/ psi )/Drell-Yan cross-sections ratio departs from the normal nuclear absorption pattern for semicentral Pb-Pb collisions and that this ratio persistently decreases up to the most central collisions. (41 refs).

  1. A new measurement of $J/\\psi$ suppression in Pb-Pb collisions at 158 GeV per nucleon

    CERN Document Server

    Alessandro, B; Arnaldi, R; Atayan, M; Beolè, S; Boldea, V; Bordalo, P; Borges, G; Castanier, C; Castor, J I; Chaurand, B; Cheynis, B; Chiavassa, E; Cicalò, C; Comets, M P; Constantinescu, S; Cortese, P; De Falco, A; De Marco, N; Dellacasa, G; Devaux, A; Dita, S; Drapier, O; Fargeix, J; Force, P; Gallio, M; Gerschel, C; Giubellino, P; Golubeva, M B; Gonin, M; Grigorian, A A; Grigorian, S; Guber, F F; Guichard, A; Gulkanian, H R; Idzik, M; Jouan, D; Karavitcheva, T L; Kluberg, L; Kurepin, A B; Le Bornec, Y; Lourenço, C; MacCormick, M; Macciotta, P; Marzari-Chiesa, A; Masera, M; Masoni, A; Monteno, M; Musso, A; Petiau, P; Piccotti, A; Pizzi, J R; Prino, F; Puddu, G; Quintans, C; Ramello, L; Ramos, S; Riccati, L; Romana, A; Santos, H; Saturnini, P; Scomparin, E; Serci, S; Shahoyan, R; Sigaudo, F; Sitta, M; Sonderegger, P; Tarrago, X; Topilskaya, N S; Usai, G L; Vercellin, Ermanno; Villatte, L; Willis, N; Wu, T

    2005-01-01

    We present a new measurement of J/psi production in Pb-Pb collisions at 158 GeV/nucleon, from the data sample collected in year 2000 by the NA50 Collaboration, under improved experimental conditions with respect to previous years. With the target system placed in vacuum, the setup was better adapted to study, in particular, the most peripheral nuclear collisions with unprecedented accuracy. The analysis of this data sample shows that the (J/psi)/Drell-Yan cross-sections ratio measured in the most peripheral Pb-Pb interactions is in good agreement with the nuclear absorption pattern extrapolated from the studies of proton-nucleus collisions. Furthermore, this new measurement confirms our previous observations that the (J/psi)/Drell-Yan cross-sections ratio departs from the normal nuclear absorption pattern for semi-central Pb-Pb collisions and that this ratio persistently decreases up to the most central collisions.

  2. Enhanced performance of GeSn source-pocket tunnel field-effect transistors for low-power applications

    Science.gov (United States)

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

    2016-07-01

    Germanium-tin (GeSn) source-pocket tunnel field-effect transistors (TFETs) are comprehensively investigated by numerical device simulations at low supply voltages. Device configurations with homo- and hetero-tunneling junctions (TJ) are analyzed and compared. It is shown that direct-gap GeSn alloys are favorable for increasing the source-pocket tunneling rate. Increasing the source Sn composition of the device may aid the on-state current increase, but the subthreshold swing (SS) is degraded because of the reduced band gap. At ultrascaled supply voltages, the GeSn hetero-TJ TFET with higher pocket Sn composition exhibits the best performance and SS, and the device performance can be further improved by increasing the Sn composition in the pocket region. These simulation results could be used to understand and optimize the performance of GeSn source-pocket TFETs, which are very promising electronic devices for low-power applications.

  3. Structure and optical properties of the Ge and Sn quantum-dots

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Embedded cluster samples Ge:CaF2 and Sn:CaF2 with different sizes less than 8nm were produced and their optical properties were examined. Electron diffraction reveals that the clusters' structures are crystallites and compared with the bulk Germanium and Stannum, lattice constants expand about 4.7% in the case of Ge:CaF2 and 5.2% of Sn:CaF2. Optical absorption and photoluminescence spectra of these samples show good agreement with the Quantum-Confinement-Effect(QCE) theory. With the decreasing of the cluster's size, the energy gap broadens and the absorption edge blueshift is observed, and the absorption edge also shifts with the changing of the fraction of Sn and Ge. The XPS results show that in the cluster state, the binding energy becomes higher.

  4. Multi-stacks of epitaxial GeSn self-assembled dots in Si: Structural analysis

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, F. [Institute for Semiconductor Engineering, University of Stuttgart, 70569 Stuttgart (Germany); Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Fischer, I. A.; Schulze, J. [Institute for Semiconductor Engineering, University of Stuttgart, 70569 Stuttgart (Germany); Benedetti, A. [CACTI, Univ. de Vigo, Campus Universitario Lagoas Marcosende 15, Vigo (Spain); Cerqueira, M. F.; Vasilevskiy, M. I. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Stefanov, S.; Chiussi, S. [Dpto. Fisica Aplicada, Univ. de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain)

    2015-03-28

    We report on the growth and structural and morphologic characterization of stacked layers of self-assembled GeSn dots grown on Si (100) substrates by molecular beam epitaxy at low substrate temperature T = 350 °C. Samples consist of layers (from 1 up to 10) of Ge{sub 0.96}Sn{sub 0.04} self-assembled dots separated by Si spacer layers, 10 nm thick. Their structural analysis was performed based on transmission electron microscopy, atomic force microscopy, and Raman scattering. We found that up to 4 stacks of dots could be grown with good dot layer homogeneity, making the GeSn dots interesting candidates for optoelectronic device applications.

  5. Multi-stacks of epitaxial GeSn self-assembled dots in Si: Structural analysis

    Science.gov (United States)

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

    2015-03-01

    We report on the growth and structural and morphologic characterization of stacked layers of self-assembled GeSn dots grown on Si (100) substrates by molecular beam epitaxy at low substrate temperature T = 350 °C. Samples consist of layers (from 1 up to 10) of Ge0.96Sn0.04 self-assembled dots separated by Si spacer layers, 10 nm thick. Their structural analysis was performed based on transmission electron microscopy, atomic force microscopy, and Raman scattering. We found that up to 4 stacks of dots could be grown with good dot layer homogeneity, making the GeSn dots interesting candidates for optoelectronic device applications.

  6. Formation and characterization of Ni/Al Ohmic contact on n+-type GeSn

    Science.gov (United States)

    Zhang, Xu; Zhang, Dongliang; Zheng, Jun; Liu, Zhi; He, Chao; Xue, Chunlai; Zhang, Guangze; Li, Chuanbo; Cheng, Buwen; Wang, Qiming

    2015-12-01

    In this study, a Ni/Al Ohmic contact on a highly doped n-type GeSn has been investigated. A specific contact resistivity as low as (2.26 ± 0.11) × 10-4 Ω cm2 was obtained with the GeSn sample annealed at a temperature of 450 °C for 30 s. The linear Ohmic behavior was attributed to the low resistance of the Ni(GeSn) phase; this behavior was determined using glancing-angle X-ray diffraction, and the quantum tunneling current through the Schottky barrier narrowed because of high doping; this phenomenon was confirmed from the contact resistance characteristics at different temperatures from 45 to 205 K.

  7. GeSn p-i-n photodetector for all telecommunication bands detection.

    Science.gov (United States)

    Su, Shaojian; Cheng, Buwen; Xue, Chunlai; Wang, Wei; Cao, Quan; Xue, Haiyun; Hu, Weixuan; Zhang, Guangze; Zuo, Yuhua; Wang, Qiming

    2011-03-28

    Using a 820 nm-thick high-quality Ge0.97Sn0.03 alloy film grown on Si(001) by molecular beam epitaxy, GeSn p-i-n photodectectors have been fabricated. The detectors have relatively high responsivities, such as 0.52 A/W, 0.23 A/W, and 0.12 A/W at 1310 nm, 1540 nm, and 1640 nm, respectively, under a 1 V reverse bias. With a broad detection spectrum (800-1800 nm) covering the whole telecommunication windows and compatibility with conventional complementary metal-oxide-semiconductors (CMOS) technology, the GeSn devices are attractive for applications in both optical communications and optical interconnects.

  8. Strangeness production in S + Pb and p + Pb collisions at 200 GeV/c per nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Sakrejda, I.

    1992-09-01

    Results from CERN experiment NA36 are reported. Cross sections for the production of singly strange particles in the S+Pb and p+Pb reactions have been measured in the rapidity range 1.250.2 GeV. A significant difference in the rapidity distributions of the lambda particles originating from these reactions suggests a fundamental difference in the strangeness production mechanism.

  9. Determination of the number of wounded nucleons in Pb+Pb collisions at 158 A GeV/c

    CERN Document Server

    Antinori, Federico; Bakke, H; Barbera, R; Beker, H; Beusch, Werner; Bloodworth, Ian J; Botje, M; Caliandro, R; Campbell, M; Cantatore, E; Carena, W; Carrer, N; De Haas, A P; Di Bari, D; Di Liberto, S; Divià, R; Elia, D; Evans, D; Fanebust, K; Fedorisin, J; Feofilov, G A; Fini, R A; Ftácnik, J; Ghidini, B; Grella, G; Gulino, M; Helstrup, H; Holme, A K; Huss, D; Jacholkowski, A; Jones, G T; Jovanovic, P; Jusko, A; Kamermans, R; Kinson, J B; Klempt, W; Knudson, K; Kolojvari, A A; Králik, I; Kuijer, P; Lenti, V; Lietava, R; Loconsole, R A; Løvhøiden, G; Lupták, M; Manzari, V; Mazzoni, M A; Martinská, G; Meddi, F; Michalon, A; Michalon-Mentzer, M E; Morando, M; Nappi, E; Navach, F; Norman, P I; Palmeri, A; Pappalardo, G S; Pastircák, B; Pellegrini, F; Pisút, J; Pisútová, N; Posa, F; Quercigh, Emanuele; Riggi, F; Röhrich, D; Romano, G; Safarík, K; Sándor, L; Schillings, E; Segato, G F; Snoeys, W; Staroba, P; Stolyarov, O I; Thompson, M; Thorsteinsen, T F; Tomasicchio, G; Torrieri, G D; Tsimbal, F A; Tulina, T A; Turrisi, R; Tveter, T S; Urbán, J; Valiev, F F; Van den Brink, A; Van de Ven, P; Van de Vyvre, P; van Eijndhoven, N; Vannucci, Luigi; Vascotto, Alessandro; Villalobos Baillie, O; Vinogradov, I; Virgili, T; Votruba, M F; Vrláková, J; Závada, P

    1999-01-01

    The charged particle multiplicity distributions measured with the WA97 and the NA57 multiplicity detectors in Pb+Pb collisions at 158 A GeV/c have been analyzed in the framework of the Wounded Nucleon Model (WNM). We obtain a good description of the data within the centrality range of our samples. This allows us to make use of the measured multiplicities to estimate the number of wounded nucleons of the collision.

  10. Upper Limit of D0 Production in Central Pb-Pb Collisions at 158A GeV

    CERN Document Server

    Alt, C; Baatar, B; Barna, D; Bartke, Jerzy; Betev, L; Bialkowska, H; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Buncic, P; Cerny, V; Christakoglou, P; Chvala, O; Cramer, J G; Csató, P; Dinkelaker, P; Eckardt, V; Flierl, D; Fodor, Z; Foka, P; Friese, V; Gál, J; Gazdzicki, M; Genchev, V; Georgopoulos, G; Gladysz-Dziadus, E; Grebieszkow, K; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kliemant, M; Kniege, S; Kolesnikov, V I; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Van Leeuwen, M; Lévai, Peter; Litov, L; Lungwitz, B; Makariev, M; Malakhov, A I; Mateev, M; Melkumov, G L; Mischke, A; Mitrovski, M; Molnár, J; Mrówczynski, S; Nicolic, V; Pálla, G; Panagiotou, A D; Panayotov, D; Petridis, A; Pikna, M; Prindle, D; Pühlhofer, F; Renfordt, R; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Schuster, T; Seyboth, P; Siklér, F; Sitár, B; Skrzypczak, E; Stefanek, G; Stock, R; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Szymanski, P; Trubnikov, V; Varga, D; Vassiliou, Maria; Veres, G I; Vesztergombi, G; Vranic, D; Wetzler, A; Wlodarczyk, Z; Yoo, I K; Zimányi, J

    2006-01-01

    Results are presented from a search for the decays D0 -> Kmin piplus and D0bar -> Kplus pimin in a sample of 3.8x10^6 central Pb-Pb events collected with a beam energy of 158A GeV by NA49 at the CERN SPS. No signal is observed. An upper limit on D0 production is derived and compared to predictions from several models.

  11. Dissolution and Interface Reactions between Palladium and Tin(Sn)-Based Solders: Part II. 63Sn-37Pb Alloy

    Science.gov (United States)

    Vianco, Paul T.; Rejent, Jerome A.; Zender, Gary L.; Hlava, Paul F.

    2010-12-01

    The interface microstructures as well as the rate kinetics of dissolution and intermetallic compound (IMC) layer formation were investigated for couples formed between molten 63Sn-37Pb (wt pct) solder and 99.9 pct Pd sheet. The solder bath temperatures were 488 K to 593 K (215 °C to 320 °C), and the immersion times were 5, 15, 30, 60, 120, and 240 seconds. The predominant IMC phases were Pd(Sn, Pb)4, PdSn4, and PdSn3. The IMC layer microstructure contained these phases and varying amounts of solder Pb- and Sn-rich phases. Isolated Pd-Sn needles appeared in the solder field at temperatures and times of ≥563 K (290 °C) and ≥30 seconds, respectively. Palladium dissolution was largely monotonic as a function of time and solder temperature, except for a sharp decline at 593 K (320 °C). The dissolution rate kinetics over 488 K to 563 K (215 °C to 290 °C) were represented by the At n exp(-Δ H/R T) equation. The values of n and Δ H were 0.67 ± 0.19 and 48 ± 20 kJ/mol, respectively, suggesting that a combination of interface reaction and solid-state mass transport processes controlled dissolution. The IMC layer grew monotonically with time and solder temperature, except at 593 K (320 °C) where growth dropped off significantly. The IMC growth rate kinetics over 488 K to 563 K (215 °C to 290 °C) exhibited values of n and Δ H equal to 0.88 ± 0.10 and 64 ± 10 kJ/mol, respectively, indicating a combination of interface reaction and solid-state diffusion processes. The extents of Pd dissolution and IMC layer development were significantly greater for molten Sn-Pb solder than the Pb-free Sn-Ag-Cu solder (Part I study) at a given test temperature.

  12. Mechanical synthesis and structural properties of the fast fluoride-ion conductor PbSnF4

    Science.gov (United States)

    Fujisaki, Fumika; Mori, Kazuhiro; Yonemura, Masao; Ishikawa, Yoshihisa; Kamiyama, Takashi; Otomo, Toshiya; Matsubara, Eiichiro; Fukunaga, Toshiharu

    2017-09-01

    A fluoride-ion conductor, γ-PbSnF4, was synthesized by the mechanical milling. In addition, β-PbSnF4 was obtained by aging the γ-PbSnF4 at 473 K. The electrical conductivity of β-PbSnF4 is relatively higher than that of γ-PbSnF4 at 298 K. The crystal structure analysis of γ- and β-PbSnF4 was carried out using neutron diffraction data. From the obtained occupancies, fluoride ions were located at the Fγ(1) normal site (62%) and Fγ(2) interstitial site (38%) in γ-PbSnF4 and the Fβ(1) normal site (31%), Fβ(2) normal site (25%), and Fβ(3) interstitial site (44%) in β-PbSnF4. In particular, the number of fluoride ions at the F interstitial site increased after the γ-to-β phase transition: 38% at Fγ(2) to 44% at Fβ(3). It is most likely that the ratio of fluoride ions to vacancies (or the effective carrier concentration) was optimized in the ;-Fβ(1)-Fβ(3)-Fβ(3)-Fβ(1)-; conduction pathways of fluoride ions in β-PbSnF4.

  13. Band alignment at the interface of PbTe/SnTe heterojunction determined by X-ray photoelectron spectroscopy

    Science.gov (United States)

    Shu, Tianyu; Ye, Zhenyu; Lu, Pengqi; Chen, Lu; Xu, Gangyi; Zhou, Jie; Wu, Huizhen

    2016-11-01

    We report the determination of band alignment of PbTe/SnTe (111) heterojunction interfaces using X-ray photoelectron spectroscopy (XPS). Multiple core levels of Pb and Sn were utilized to determine the valence band offset (VBO) of the heterojunction. The XPS result shows a type-III band alignment with the VBO of 1.37+/- 0.18 \\text{eV} and the conduction band offset (CBO) of 1.23+/- 0.18 \\text{eV} . The experimental determination of the band alignment of the PbTe/SnTe heterojunction shall benefit the improvement of PbTe/SnTe-related optoelectronic and electronic devices.

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

    Science.gov (United States)

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

    2016-04-01

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

  15. Topological Weyl semimetals in the chiral antiferromagnetic materials Mn3Ge and Mn3Sn

    Science.gov (United States)

    Yang, Hao; Sun, Yan; Zhang, Yang; Shi, Wu-Jun; Parkin, Stuart S. P.; Yan, Binghai

    2017-01-01

    Recent experiments revealed that Mn3Sn and Mn3Ge exhibit a strong anomalous Hall effect at room temperature, provoking us to explore their electronic structures for topological properties. By ab initio band structure calculations, we have observed the existence of multiple Weyl points in the bulk and corresponding Fermi arcs on the surface, predicting antiferromagnetic Weyl semimetals in Mn3Ge and Mn3Sn. Here the chiral antiferromagnetism in the Kagome-type lattice structure is essential to determine the positions and numbers of Weyl points. Our work further reveals a new guiding principle to search for magnetic Weyl semimetals among materials that exhibit a strong anomalous Hall effect.

  16. Selective growth of fully relaxed GeSn nano-islands by nanoheteroepitaxy on patterned Si(001)

    Science.gov (United States)

    Schlykow, V.; Klesse, W. M.; Niu, G.; Taoka, N.; Yamamoto, Y.; Skibitzki, O.; Barget, M. R.; Zaumseil, P.; von Känel, H.; Schubert, M. A.; Capellini, G.; Schroeder, T.

    2016-11-01

    In this letter, we explore in detail the potential of nanoheteroepitaxy to controllably fabricate high quality GeSn nano-structures and to further improve the crystallinity of GeSn alloys directly grown on Si(001). The GeSn was grown by molecular beam epitaxy at relatively high temperatures up to 750 °C on pre-patterned Si nano-pillars embedded in a SiO2 matrix. The best compromise between selective GeSn growth and homogenous Sn incorporation of 1.4% was achieved at a growth temperature of 600 °C. X-ray diffraction measurements confirmed that our growth approach results in both fully relaxed GeSn nano-islands and negligible Si interdiffusion into the core of the nanostructures. Detailed transmission electron microscopy characterizations show that only the small GeSn/Si interface area reveals defects, such as stacking faults. Importantly, the main part of the GeSn islands is defect-free and of high crystalline quality. The latter was further demonstrated by photoluminescence measurements where a clear redshift of the direct ΓC-ΓV transition was observed with increasing Sn content.

  17. Direct bandgap GeSn light emitting diodes for short-wave infrared applications grown on Si

    Science.gov (United States)

    von den Driesch, Nils; Stange, Daniela; Wirths, Stephan; Rainko, Denis; Mussler, Gregor; Stoica, Toma; Ikonic, Zoran; Hartmann, Jean-Michel; Grützmacher, Detlev; Mantl, Siegfried; Buca, Dan

    2016-03-01

    The experimental demonstration of fundamental direct bandgap, group IV GeSn alloys has constituted an important step towards realization of the last missing ingredient for electronic-photonic integrated circuits, i.e. the efficient group IV laser source. In this contribution, we present electroluminescence studies of reduced-pressure CVD grown, direct bandgap GeSn light emitting diodes (LEDs) with Sn contents up to 11 at.%. Besides homojunction GeSn LEDs, complex heterojunction structures, such as GeSn/Ge multi quantum wells (MQWs) have been studied. Structural and compositional investigations confirm high crystalline quality, abrupt interfaces and tailored strain of the grown structures. While also being suitable for light absorption applications, all devices show light emission in a narrow short-wave infrared (SWIR) range. Temperature dependent electroluminescence (EL) clearly indicates a fundamentally direct bandgap in the 11 at.% Sn sample, with room temperature emission at around 0.55 eV (2.25 µm). We have, however, identified some limitations of the GeSn/Ge MQW approach regarding emission efficiency, which can be overcome by introducing SiGeSn ternary alloys as quantum confinement barriers.

  18. The effect of intermetallic compound morphology on Cu diffusion in Sn-Ag and Sn-Pb solder bump on the Ni/Cu Under-bump metallization

    Science.gov (United States)

    Jang, Guh-Yaw; Duh, Jenq-Gong

    2005-01-01

    The eutectic Sn-Ag solder alloy is one of the candidates for the Pb-free solder, and Sn-Pb solder alloys are still widely used in today’s electronic packages. In this tudy, the interfacial reaction in the eutectic Sn-Ag and Sn-Pb solder joints was investigated with an assembly of a solder/Ni/Cu/Ti/Si3N4/Si multilayer structures. In the Sn-3.5Ag solder joints reflowed at 260°C, only the (Ni1-x,Cux)3Sn4 intermetallic compound (IMC) formed at the solder/Ni interface. For the Sn-37Pb solder reflowed at 225°C for one to ten cycles, only the (Ni1-x,Cux)3Sn4 IMC formed between the solder and the Ni/Cu under-bump metallization (UBM). Nevertheless, the (Cu1-y,Niy)6Sn5 IMC was observed in joints reflowed at 245°C after five cycles and at 265°C after three cycles. With the aid of microstructure evolution, quantitative analysis, and elemental distribution between the solder and Ni/Cu UBM, it was revealed that Cu content in the solder near the solder/IMC interface played an important role in the formation of the (Cu1-y,Niy)6Sn5 IMC. In addition, the diffusion behavior of Cu in eutectic Sn-Ag and Sn-Pb solders with the Ni/Cu UBM were probed and discussed. The atomic flux of Cu diffused through Ni was evaluated by detailed quantitative analysis in an electron probe microanalyzer (EPMA). During reflow, the atomic flux of Cu was on the order of 1016-1017 atoms/cm2sec in both the eutectic Sn-Ag and Sn-Pb systems.

  19. High-k gate stacks on low bandgap tensile strained Ge and GeSn alloys for field-effect transistors.

    Science.gov (United States)

    Wirths, Stephan; Stange, Daniela; Pampillón, Maria-Angela; Tiedemann, Andreas T; Mussler, Gregor; Fox, Alfred; Breuer, Uwe; Baert, Bruno; San Andrés, Enrique; Nguyen, Ngoc D; Hartmann, Jean-Michel; Ikonic, Zoran; Mantl, Siegfried; Buca, Dan

    2015-01-14

    We present the epitaxial growth of Ge and Ge0.94Sn0.06 layers with 1.4% and 0.4% tensile strain, respectively, by reduced pressure chemical vapor deposition on relaxed GeSn buffers and the formation of high-k/metal gate stacks thereon. Annealing experiments reveal that process temperatures are limited to 350 °C to avoid Sn diffusion. Particular emphasis is placed on the electrical characterization of various high-k dielectrics, as 5 nm Al2O3, 5 nm HfO2, or 1 nmAl2O3/4 nm HfO2, on strained Ge and strained Ge0.94Sn0.06. Experimental capacitance-voltage characteristics are presented and the effect of the small bandgap, like strong response of minority carriers at applied field, are discussed via simulations.

  20. Effects of processing conditions on PbGeTe film performance

    Science.gov (United States)

    Zhang, Su-ying; Cheng, Chiping; Ling, Jiehua; Fan, Bin; Zou, Ziying; Wang, Zhiyun; Zhang, Jiajian; Shi, Tian-Shen; Wang, Ge-ya

    1998-02-01

    Characters of PbGeTe single layer is likely affected by various factors. The adhesion of PbGeTe single layer and PbGeTe/ZnS multilayer deposited on Si substrate by PVD method is investigated by means of x-ray diffraction. The correlation of layer growing rate and the preferred orientation of Si wafer is studied by the grind angle to measure the thickness method. The particle structure of films on various surface situations is studied by the image analysis. It has been noticed, that the adhesion of PbGeTe single layer is stronger in strength than that of the PbTe single layer, which shows little correlation with the preferred orientation of the substrate. The adhesive strength of the films can be improved by inserting thin layer of Ge or oxide layer. We have found that the layer growing rate varies with the preferred orientation of the substrate, we have also noticed that the particle structure of the films can be affected by the roughness of the substrate and the polishing method. Finally, the refractive index of Pb1-xGexTe(x equals 0.08) single layer was calculated.

  1. New type of quantum spin Hall insulators in hydrogenated PbSn thin films

    Science.gov (United States)

    Liu, Liang; Qin, Hongwei; Hu, Jifan

    2017-01-01

    The realization of a quantum spin Hall (QSH) insulator working at high temperature is of both scientific and technical interest since it supports spin-polarized and dssipationless edge states. Based on first-principle calculations, we predicted that the two-dimensional (2D) binary compound of lead and tin (PbSn) in a buckled honeycomb framework can be tuned into a topological insulator with huge a band gap and structural stability via hydrogenation or growth on special substrates. This heavy-element-based structure is sufficiently ductile to survive the 18 ps molecular dynamics (MD) annealing to 400 K, and the band gap opened by strong spin-orbital-coupling (SOC) is as large as 0.7 eV. These characteristics indicate that hydrogenated PbSn (H-PbSn) is an excellent platform for QSH realization at high temperature. PMID:28218297

  2. Enhancement of the magnetic entropy change on substitution of Ge in ErSn1.1Ge0.9

    Science.gov (United States)

    Gupta, Sachin; Pal, Lakhan; Suresh, K. G.

    2015-05-01

    Magnetic and magnetocaloric properties of polycrystalline ErSn0.5Ge1.5 have been studied. It is found that substitution of Ge for Sn in ErSn1.1Ge0.9 results in a nominal increase in the magnetic moment, but a considerable enhancement in the magnetocaloric effect. The magnetocaloric effect, calculated from magnetization data, shows a large value of 13 J/kg K for a field of 50 kOe. Magnetization, heat capacity, and magnetocaloric data reveal field induced metamagnetic transition in this compound.

  3. Indium (In)- and tin (Sn)-based metal induced crystallization (MIC) on amorphous germanium (α-Ge)

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Dong-Ho; Park, Jin-Hong, E-mail: jhpark9@skku.edu

    2014-12-15

    Highlights: • In- and Sn-based MIC phenomenon on amorphous (α)-Ge is newly reported. • The In- and Sn-MIC phenomenon respectively started at 250 °C and 400 °C. • The Sn-MIC process presents higher sheet resistance and bigger crystal grains. - Abstract: In this paper, metal-induced crystallization (MIC) phenomenon on α-Ge by indium (In) and tin (Sn) are thoroughly investigated. In- and Sn-MIC process respectively started at 250 °C and 400 °C. Compared to the previously reported MIC samples including In-MIC, Sn-MIC process presented higher sheet resistance (similar to that of SPC) and bigger crystal grains above 50 nm (slightly smaller than that of SPC). According to SIMS analysis, Sn atoms diffused more slowly into Ge than In at 400 °C, providing lower density of heterogeneous nuclei induced by metals and consequently larger crystal grains.

  4. Passivation of multiple-quantum-well Ge0.97Sn0.03/Ge p-i-n photodetectors

    Science.gov (United States)

    Morea, Matthew; Brendel, Corinna E.; Zang, Kai; Suh, Junkyo; Fenrich, Colleen S.; Huang, Yi-Chiau; Chung, Hua; Huo, Yijie; Kamins, Theodore I.; Saraswat, Krishna C.; Harris, James S.

    2017-02-01

    We study the effect of surface passivation on pseudomorphic multiple-quantum-well Ge0.97Sn0.03/Ge p-i-n photodetectors. A combination of ozone oxidation to form GeOx and GeSnOx on the surface of the diodes followed by atomic layer deposition of Al2O3 for protection of these native oxides provides reduced dark current. With a temperature-dependent investigation of dark current, we calculate the activation energy to be 0.26 eV at a bias of -0.1 V and 0.05 eV at -1 V for the sample passivated by this ozone method. Based on these activation energy results, we find that the current is less dominated by bulk tunneling at lower reverse bias values; hence, the effect of surface passivation is more noticeable with nearly an order-of-magnitude improvement in dark current for the ozone-passivated sample compared to control devices without the ozone treatment at a voltage of -0.1 V. Passivation also results in a significant enhancement of the responsivity, particularly for shorter wavelengths, with 26% higher responsivity at 1100 nm and 16% higher performance at 1300 nm.

  5. Temperature-dependent electroluminescence from GeSn heterojunction light-emitting diode on Si substrate

    Science.gov (United States)

    Chang, Chiao; Li, Hui; Huang, Ssu-Hsuan; Lin, Li-Chien; Cheng, Hung-Hsiang

    2016-04-01

    The electroluminescence from a Ge/GeSn/Ge p-i-n light-emitting diode on Si was investigated under different temperatures ranging from 25 to 150 K. The diode was operated at a low injection current density of 13 A/cm2. We obtained no-phonon- and phonon-assisted replicas in emission spectra. Also, the relationship between indirect bandgap energy and temperature was investigated. The temperature-dependent bandgap energy followed Varshni’s empirical expression with α = 4.884 × 10-4 eV/K and β = 130 K.

  6. Formation of Ge-Sn nanodots on Si(100 surfaces by molecular beam epitaxy

    Directory of Open Access Journals (Sweden)

    Yu Ing-Song

    2011-01-01

    Full Text Available Abstract The surface morphology of Ge0.96Sn0.04/Si(100 heterostructures grown at temperatures from 250 to 450°C by atomic force microscopy (AFM and scanning tunnel microscopy (STM ex situ has been studied. The statistical data for the density of Ge0.96Sn0.04 nanodots (ND depending on their lateral size have been obtained. Maximum density of ND (6 × 1011 cm-2 with the average lateral size of 7 nm can be obtained at 250°C. Relying on the reflection of high energy electron diffraction, AFM, and STM, it is concluded that molecular beam growth of Ge1-xSnx heterostructures with the small concentrations of Sn in the range of substrate temperatures from 250 to 450°C follows the Stranski-Krastanow mechanism. Based on the technique of recording diffractometry of high energy electrons during the process of epitaxy, the wetting layer thickness of Ge0.96Sn0.04 films is found to depend on the temperature of the substrate.

  7. Electroluminescence from GeSn heterostructure pin diodes at the indirect to direct transition

    Energy Technology Data Exchange (ETDEWEB)

    Gallagher, J. D.; Menéndez, J. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Senaratne, C. L.; Sims, P.; Kouvetakis, J. [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604 (United States); Aoki, T. [LeRoy Eyring Center for Solid State Science, Arizona State University, Tempe, Arizona 85287- 1704 (United States)

    2015-03-02

    The emission properties of GeSn heterostructure pin diodes have been investigated. The devices contain thick (400–600 nm) Ge{sub 1−y}Sn{sub y} i-layers spanning a broad compositional range below and above the crossover Sn concentration y{sub c} where the Ge{sub 1−y}Sn{sub y} alloy becomes a direct-gap material. These results are made possible by an optimized device architecture containing a single defected interface thereby mitigating the deleterious effects of mismatch-induced defects. The observed emission intensities as a function of composition show the contributions from two separate trends: an increase in direct gap emission as the Sn concentration is increased, as expected from the reduction and eventual reversal of the separation between the direct and indirect edges, and a parallel increase in non-radiative recombination when the mismatch strains between the structure components is partially relaxed by the generation of misfit dislocations. An estimation of recombination times based on the observed electroluminescence intensities is found to be strongly correlated with the reverse-bias dark current measured in the same devices.

  8. Self-assembled strained GeSiSn nanoscale structures grown by MBE on Si(100)

    Science.gov (United States)

    Nikiforov, A. I.; Timofeev, V. A.; Tuktamyshev, A. R.; Yakimov, A. I.; Mashanov, V. I.; Gutakovskii, A. K.

    2017-01-01

    Gradual relaxation of elastic deformations in a silicon layer at the growth of a covering layer on strained layers was established. The dependence of the thickness of a silicon film, where full elastic strain relaxation occurs, on the germanium layer thickness was determined. The dependence of the critical thickness of 2D-3D transition of temperature and composition of the GeSiSn film on Si(100) was studied. Regularities of the formation of multilayer structures on quantum wells comprising pseudomorphous GeSiSn layers without relaxed buffer layers but creating the structures directly on Si. A possibility of synthesizing multilayer structures by molecular beam epitaxy was shown, and the crystal lattice constants using the high-resolution transmission electron microscopy were determined. Based on multilayer GeSiSn/Si structures the p-i-n-diodes, which demonstrated the photoresponse increasing by several orders of magnitude compared to the Sn-free structures at an increase in the Sn content, were created.

  9. Influence of Sn-substitution on the thermoelectric properties of the clathrate type-I, Ba8Zn(x)Ge(46-x-y)Sn(y).

    Science.gov (United States)

    Falmbigl, Matthias; Grytsiv, Andriy; Rogl, Peter; Yan, Xinlin; Royanian, Esmaeil; Bauer, Ernst

    2013-02-28

    A systematic investigation is presented on the influence of Sn-substitution in the clathrate-I compound Ba(8)Zn(x)Ge(46-x-y)Sn(y), particularly for the crystal structure and thermoelectric properties including electrical resistivity, Seebeck coefficient, and thermal conductivity. Two series of samples were prepared to explore the changes for different Sn-contents, (y), and to define the optimum Zn-content, (x), for Ba(8)Zn(x)Ge(46-x-y)Sn(y). Sn-incorporation leads to a linear expansion of the unit cell parameters. Sn-atoms occupy the 6d and 24k positions of the clathrate type-I structure (SG Pm3n, standardized setting). Whereas the electrical resistivity and the Seebeck coefficient modify only slightly compared to Ba(8)Zn(x)Ge(46-x), the thermal conductivity is significantly decreased by the Sn-atoms incorporated into the clathrate-I framework. Furthermore the charge carrier mobility is larger and the effective mass (m* = 1.7 m(e)) is much smaller than those of the ternary compound Ba(8)Zn(x)Ge(46-x). The maximum thermoelectric figure of merit is improved by 80% and reaches ZT = 0.82 at 850 K for Ba(8)Zn(7.66)Ge(36.55)Sn(1.79).

  10. Research Update: Prediction of high figure of merit plateau in SnS and solid solution of (Pb,Sn)S

    Science.gov (United States)

    Hao, Shiqiang; Dravid, Vinayak P.; Kanatzidis, Mercouri G.; Wolverton, Christopher

    2016-10-01

    Direct conversion between thermal and electrical energy can be achieved by thermoelectric materials, which provide a viable route for power generation and solid state refrigeration. Here, we use a combination of energetic, electronic, and vibrational first-principles based results to predict the figure of merit performance in hole doped single crystals of SnS and (Pb,Sn)S. We find high ZT values for both materials, specifically for (Pb,Sn)S along the b-axis. Both SnS and (Pb,Sn)S have excellent power factors when doped, due to a combination of increased electrical conductivity (due to doping) and a significantly enhanced Seebeck coefficient obtained by a doping-induced multiband effect. Anharmonic phonon calculations combined with a Debye-Calloway model show that the lattice thermal conductivity of both compounds is low, due to intrinsic anharmonicity, and is lowered further by the random, solid solution nature of the cation sublattice of (Pb,Sn)S. (Pb,Sn)S exhibits a high ZT plateau ranging from 1.3 at 300 K to 1.9 at 800 K. The overall ZT of the hole doped (Pb,Sn)S crystals is predicted to outperform most of the current state-of-the-art thermoelectric sulfide materials.

  11. Multistrange Hyperon Production in Pb+Pb collisions at 30, 40, 80 and 158 A$\\cdot$GeV

    CERN Document Server

    Mitrovski, Michael; Anticic, T; Baatar, B; Barna, D; Bartke, Jerzy; Behler, M; Betev, L; Bialkowska, H; Billmeier, A; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Brun, R; Buncic, P; Cerny, V; Christakoglou, P; Chvala, O; Cramer, J G; Csató, P; Darmenov, N; Dimitrov, A; Dinkelaker, P; Eckardt, V; Filip, P; Fischer, H G; Flierl, D; Fodor, Z; Foka, P; Freund, P; Friese, V; Gál, J; Gazdzicki, M; Georgopoulos, G; Gladysz-Dziadus, E; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kliemant, M; Kniege, S; Kolesnikov, V I; Kollegger, T; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Van Leeuwen, M; Lévai, Peter; Litov, L; Lungwitz, B; Makariev, M; Malakhov, A I; Markert, C; Mateev, M; Mayes, B W; Melkumov, G L; Meurer, C; Mischke, A; Molnár, J; Mrówczynski, S; Pálla, G; Panagiotou, A D; Panayotov, D; Perl, K; Petridis, A; Pikna, M; Pinsky, L; Pühlhofer, F; Reid, J G; Renfordt, R E; Retyk, W; Richard, A; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Sann, H; Schmitz, N; Seyboth, P; Siklér, F; Sitár, B; Skrzypczak, E; Stefanek, G; Stock, R; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Trainor, T A; Varga, D; Vassiliou, Maria; Veres, G I; Vesztergombi, G; Vranic, D; Wenig, S; Wetzler, A; Wlodarczyk, Z; Yoo, I K; Zaranek, J; Zimányi, J; Mitrovski, Michael

    2004-01-01

    A non-monotonic energy dependence of the $K^{+} / \\pi^{+}$ ratio with a sharp maximum close to 30 A$\\cdot$GeV is observed in central Pb+Pb collisions. Within a statistical model of the early stage, this is interpreted as a sign of the phase transition to a QGP, which causes a sharp change in the energy dependence of the strangeness to entropy ratio. This observation naturally motivates us to study the production of multistrange hyperons ($\\Xi$, $\\Omega$) as a function of the beam energy. Furthermore it was suggested that the kinematic freeze-out of $\\Omega$ takes place directly at QGP hadronization. If this is indeed the case, the transverse momentum spectra of the $\\Omega$ directly reflect the transverse expansion velocity of a hadronizing QGP. In this report we show preliminary NA49 results on $\\Omega^{-}$ and $\\bar{\\Omega}^{+}$ production in central Pb+Pb collisions at 40 and 158 A$\\cdot$GeV and compare them to measurements of $\\Xi^{-}$ and $\\bar{\\Xi}^{+}$ production in central Pb+Pb collisions at 30, 40, ...

  12. Influences of temperature, H2SO4 concentration and Sn content on corrosion behaviors of PbSn alloy in sulfuric acid solution

    Science.gov (United States)

    Li, D. G.; Chen, D. R.; Wang, J. D.; Chen, H. S.

    2011-10-01

    The influences of temperature, H2SO4 concentration and Sn content on corrosion behaviors of PbSn alloys in sulfuric acid solution were investigated by potentiodynamic curve, cyclic voltammetry (CV), linear sweeping voltage (LSV), electrochemical impedance spectra (EIS), a.c. voltammetry (ACV) and Mott-Schottky analysis. The microstructure of the corrosion layer on PbSn alloy was analyzed by scanning electron microscopy (SEM). The results showed that the corrosion resistance of PbSn alloy increased with ascending Sn content and H2SO4 concentration, the increment of temperature can decrease the corrosion resistance of PbSn alloy in H2SO4 solution. The conductivity of the anodic film on PbSn alloy was enhanced with increasing temperature, ascending Sn content and descending H2SO4 concentration. SEM result revealed that the corrosion film after cyclic voltammetry was consisted of tetragonal crystal, the porosity enlarged with decreasing temperature, Sn content and H2SO4 concentration.

  13. Transverse mass distributions of neutral pions from 208Pb-induced reactions at 158 A GeV

    NARCIS (Netherlands)

    Aggarwal, M.M.; Agnihotri, A.; Ahammed, Z.A.; Angelis, A.L.S.; Antonenko, V.; Arefiev, V.; Astakhov, V.; Avdeitchikov, V.; Awes, T.C.; Baba, P.V.K.S.; Badyal, S.K.; Barlag, C.; Bathe, S.; Batiounia, B.; Bernier, T.; Bhalla, K.B.; Bhatia, V.S.; Blume, C.; Bock, R.; Bohne, E.-M.; Böröcz, Z.K.; Bucher, D.; Buijs, A.; Büsching, H.; Carlén, L.; Chalyshev, V.; Chattopadhyay, S.; Cherbatchev, R.; Chujo, T.; Claussen, A.; Das, A.C.; Decowski, M.P.; Delagrange, H.; Djordjadze, V.; Donni, P.; Doubovik, I.; Dubey, A.K.; Dutt, S.; Dutta Majumdar, M.R.; El Chenawi, K.; Eliseev, S.; Enosawa, K.; Foka, P.; Fokin, S.; Ganti, M.S.; Garpmann, S.; Gavrishchuk, O.; Geurts, F.; Ghosh, T.K.; Glasow, R.; Gupta, S.K.; Guskov, B.; Gustafsson, H.-A.; Gutbrod, H.H.; Higuchi, R.; Hrivnacova, I.; Ippolitov, M.; Kalechofsky, H.; Kamermans, R.; Kampert, K.-H.; Karadjev, K.; Karpio, K.; Kato, S.; Kees, S.; Klein-Bösing, C.; Knoche, S.; Kolb, B.; Kosarev, I.; Koutcheryaev, I.; Krümpel, T.; Kugler, A.; Kulinich, P.; Kurata, M.; Kurita, K.; Kuzmin, N.; Langbein, I.; Bevedev, A.; Lee, Y.Y.; Löhner, H.; Luquin, L.; Mahapatra, D.P.; Manko, V.; Martin, M.; Martinez, G.; Maximov, A.; Mgebrichvili, G.; Miake, Y.; Mir, Md.F.; Mishra, G.C.; Mitamoto, Y.; Mohanti, B.; Mora, M.-J.; Morrison, D.; Mukhopadhyay, D.S.; Naef, H.; Nandi, B.K.; Nayak, S.K.; Nayak, T.K.; Neumaier, S.

    Results on transverse mass spectra of neutral pious measured at central rapidity are presented for impact parameter selected 158-A GeV Pb + Pb-1 and Pb + Nb collisions. The distributions cover the range 0.5 GeV/c(2) less than or equal to MT - Mo less than or equal to 4 GeV/c(2). The change of the

  14. sup 119 Sn-Moessbauer spectroscopic study of the single phase of Bi(Pb)-Sr-Ca-Cu(Sn)-O

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Y. (Dept. of Electrical Engineering, Fukuoka Univ. (Japan)); Nishida, T. (Dept. of Chemistry, Kyushu Univ., Fukuoka (Japan)); Katada, M. (Dept. of Chemistry, Tokyo Metropolitan Univ. (Japan)); Deshimaru, Y.; Miura, N.; Yamazoe, N. (Dept. of Materials Science and Tech., Graduate School of Engineering Sciences, Kyushu Univ., Fukuoka (Japan))

    1991-12-01

    Tin-doped samples of the high-Tc (2223) phase of Bi-Pb-Sr-Ca-Cu-O superconductor have been prepared by a conventional sintering method. Sintering conditions were carefully selected to obtain the single high-Tc phase. {sup 119}Sn-Moessbauer spectra have been measured in the temperature range from 4.2 to 300 K. The temperature dependence of the recoilless fraction (f) is well understood by the temperature dependence of the normal phonon. (orig.).

  15. Interaction Kinetics between Sn-Pb Solder Droplet and Au/Ni/Cu Pad

    Institute of Scientific and Technical Information of China (English)

    Fuquan LI; Chunqing WANG; Yanhong TIAN

    2006-01-01

    The interfacial phenomena of the Sn-Pb solder droplet on Au/Ni/Cu pad are investigated. A continuous AuSn2and needle-like AuSn4 are formed at the interface after the liquid state reaction (soldering). The interfacial reaction between the solder and Au layer continues during solid state aging with AuSn4 breaking off from the interface and felling into the solder. The kinetics of Au layer dissolution and diffusion into the solder during soldering and aging is analyzed to elucidate intermetallic formation mechanism at the solder/Au pad interface.The concentration of Au near the solder/pad interface is identified to increase and reach the solubility limit during the period of liquid state reaction. During solid state reaction, the thickening of Au-Sn compound is mainly controlled by element diffusion.

  16. Electrical and Optical Characterization of Si-Ge-Sn

    Science.gov (United States)

    2012-03-01

    the typical mounting brackets were too large to hold the samples. The FTIR uses a Michelson -type interferometer. The optical path difference is...al., "Tensile-strained, n-type Ge as a Gain Medium for Monolithic Laser Integration on Si," Optical Express 15 (18), 11272 (2007). 32. W. C. Dash

  17. The effect of low Au concentrations on the properties of eutectic Sn/Pb

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, P.A.

    1992-05-01

    This study was of the effects moderately low Au concentrations ({le} 10 wt%) have on the mechanical properties and microstructure of an eutectic Sn/Pb alloy. Vibration (60--90 Hz swept sine wave for 30 hours) and thermal cycling (0--110C for 1450 cycles) reliability tests were performed on fine pitch leaded chip carriers using eutectic Sn/Pb solder on PCBs (printed circuit boards) with 0, 5, 10, 20, and 50{mu}in nominal Au thicknesses. Testing was also performed on double shear creep specimens consisting of arrays of regular pitch joints. There was a dramatic increase in the number of joints containing voids with increasing Au concentration, an effect more pronounced in the creep joints than in the reliability joints. These voids tended to coalesce and grow during rework simulation of the reliability joints. AuSn{sub 4} intermetallics present in toe of 4.8 wt% (50 {mu}in) Au vibration joints rotated from initial vertical perpendicular to surface of PCB metallization, solidification positions to roughly horizontal (parallel to plating surface) orientations during rework simulation and during aging of the parts. The AuSn{sub 4} intermetallics in the toe of the 4.8 wt% (50{mu}in) Au reflowed joints also rotated after vibration testing. No joint failures were observed in either vibration tested or thermally cycled specimens. Cracks formed in some of the vibration tested specimen joints under the heel of the gull-wing lead at Pb-rich phases. Thermally cycled specimens showed eutectic microstructure and intermetallic coarsening without crack formation. Creep tests showed loss of the superplasticity in eutectic Sn/Pb alloys with even the lowest Au concentration tested of 0.2 wt% Au. Intermetallic rotation was not a factor in crack propagation, but void presence was. Cracks tended to form in joints containing voids before forming in void-free joints. Crack propagation followed Sn/Sn grain boundaries and Sn/Pb phase boundaries from Pb-rich phase to Pb-rich phase.

  18. Analysis for positions of Sn atoms in epitaxial Ge{sub 1−x}Sn{sub x} film in low temperature depositions

    Energy Technology Data Exchange (ETDEWEB)

    Kamiyama, Eiji, E-mail: ejkamiyama@aol.com [Dept. of Comm. Eng., Okayama Pref. Univ., 111 Kuboki, Soja, Okayama 719-1197 (Japan); Sueoka, Koji [Dept. of Comm. Eng., Okayama Pref. Univ., 111 Kuboki, Soja, Okayama 719-1197 (Japan); Nakatsuka, Osamu; Taoka, Noriyuki; Zaima, Shigeaki [Dept. of Cryst. Mat. Sci., Grad. School of Eng., Nagoya Univ., Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Izunome, Koji; Kashima, Kazuhiko [Technology, GlobalWafers Japan Corp. Ltd, 6-861-5 Higashiko, Seiro, Niigata 957-0197 (Japan)

    2014-04-30

    We investigated the position of Sn atoms in Ge{sub 1−x}Sn{sub x} film grown at a low temperature by using the Extended X-ray Absorption Fine Structure (EXAFS) method. Vacancies had been expected to be introduced near the growing surface vicinity of a Sn atom and located at a split-vacancy position due to the binding nature between a Sn atom and a vacancy, which was predicted by the calculation for a bulk model in the literature. However, the EXAFS showed that almost all Sn atoms were located at the substitutional position and did not form a split-vacancy. - Highlights: • Extended X-ray Absorption Fine Structure (EXAFS) study of epitaxial Ge{sub 1−x}Snx film • EXAFS shows that almost all Sn atoms are located at substitutional positions. • The amount of vacancies introduced in low-temperature epitaxial growth is small.

  19. Atom probe tomography study on Ge{sub 1−x−y}Sn{sub x}C{sub y} hetero-epitaxial film on Ge substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kamiyama, Eiji, E-mail: ejkamiyama@aol.com [Technology, GlobalWafers Japan Corp. Ltd., 6-861-5 Higashiko, Seiro, Niigata 957-0197 (Japan); Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja-shi, Okayama-ken 719-1197 (Japan); Sueoka, Koji [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja-shi, Okayama-ken 719-1197 (Japan); Terasawa, Kengo; Yamaha, Takashi; Nakatsuka, Osamu [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Zaima, Shigeaki [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Izunome, Koji; Kashima, Kazuhiko [Technology, GlobalWafers Japan Corp. Ltd., 6-861-5 Higashiko, Seiro, Niigata 957-0197 (Japan); Uchida, Hiroshi [Physical Analysis Technology Center, Toshiba Nanoanalysis Corporation, 8 Shinsugita-cho, Isogo-ku, Yokohama 235-8522 (Japan)

    2015-10-01

    We analyzed the incorporation of C atoms into a ternary alloy Ge{sub 1−x−y}Sn{sub x}C{sub y} epitaxial film on Ge substrates on a sub-nanometer scale by using atom probe tomography. Periodic atom distributions from individual (111) atomic planes were observed both in the Ge{sub 1−x−y}Sn{sub x}C{sub y} film and at the Ge substrates. Sn/C atoms had non-uniform distributions in the film. They also demonstrated a clear positive correlation in their distributions. Substitutional C atoms were only incorporated into the film when an Sn atom beam was applied onto the substrates under film growth conditions. - Highlights: • Incorporation of C atoms into epitaxial Ge{sub 1−x−y}Sn{sub x}C{sub y} film was studied. • Individual (111) atomic planes were observed by atom probe tomography. • Sn/C atoms had non-uniform distributions in the film. • Clear positive correlation in Sn/C atoms distributions was obtained.

  20. Epitaxial Growth of GeGaAs.

    Science.gov (United States)

    1981-06-01

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

  1. Current-voltage characteristics of Pb and Sn granular superconducting nanowires

    DEFF Research Database (Denmark)

    Michotte, S.; Mátéfi-Tempfli, Stefan; Piraux, L.

    2003-01-01

    Current-voltage characteristics of Pb and Sn granular superconducting nanowires were investigated. The nanowires were prepared by electrodeposition in nanoporous membranes. It was observed that phase-slip-centers were formed far below the critical temperature when dc current was introduced inside...

  2. Spin-orbit coupling and magnetic interactions in Si(111):{C,Si,Sn,Pb}

    Science.gov (United States)

    Badrtdinov, D. I.; Nikolaev, S. A.; Katsnelson, M. I.; Mazurenko, V. V.

    2016-12-01

    We study the magnetic properties of the adatom systems on a semiconductor surface Si(111):{C,Si,Sn,Pb}-(√{3 }×√{3 }) . On the basis of all-electron density functional theory calculations we construct effective low-energy models taking into account spin-orbit coupling and electronic correlations. The Hartree-Fock simulations for the unit cell with nine correlated orbitals put forward insulating ground states with the noncollinear 120∘-Néel (for C, Si, Sn monolayer coverages) and 120∘-row-wise (for Pb adatom) antiferromagnetic orderings. The corresponding spin Hamiltonians with anisotropic exchange interactions are derived by means of the superexchange theory and the calculated Dzyaloshinskii-Moriya interactions in the systems with Sn and Pb adatoms are revealed to be very strong and compatible with the isotropic exchange couplings. To simulate the excited magnetic states we solve the constructed spin models by means of the Monte Carlo method, where at low temperatures and zero magnetic field we observe complex spin spiral patterns in Sn/Si(111) and Pb/Si(111). On this basis the formation of antiferromagnetic skyrmion lattice states at high magnetic fields in the adatom s p electron systems is discussed.

  3. Centrality dependence of K+ produced in Pb+Pb collisions at 158 GeV per nucleon

    CERN Document Server

    Arsenescu, R; Baglin, C; Beck, H P; Borer, K; Bussière, A; Elsener, K; Gorodetzky, P; Guillaud, J P; Hess, P; Kabana, S; Klingenberg, R; Lehmann, G; Lindén, T; Lohmann, K D; Mommsen, R K; Moser, U; Pretzl, Klaus P; Schacher, J; Stoffel, F; Spiwoks, R; Tuominiemi, Jorma; Weber, M; Gorodetzky, Ph.

    2001-01-01

    The NA52 collaboration searches for a discontinuous behaviour of charged kaons produced in Pb+Pb collisions at 158 A GeV as a function of the impact parameter, which could reveal a hadron to quark-gluon plasma (QGP) phase transition. The K+ yield is found to grow proportional to the number of participating ('wounded') nucleons N, above N=100. Previous NA52 data agree with the above finding and show a discontinuous behaviour in the kaon centrality dependence near N=100, marking the onset of strangeness enhancement -over e.g. p+A data at the same \\sqrt{s}- in a chemically equilibrated phase.

  4. Centrality dependence of K+ produced in Pb+Pb collisions at 158 GeV per nucleon

    CERN Document Server

    Arsenescu, R; Borer, K; Kabana, S; Klingenberg, R; Lehmann, G; Mommsen, R K; Moser, U; Pretzl, Klaus P; Schacher, J; Spiwoks, R; Weber, M; Elsener, K; Lohmann, K D; Baglin, C; Bussière, A; Guillaud, J P; Lindén, T; Tuominiemi, Jorma; Gorodetzky, P; Gorodetzky, Ph.

    2000-01-01

    The NA52 collaboration searches for a discontinuous behaviour of charged kaons produced in Pb+Pb collisions at 158 A GeV as a function of the impact parameter, which could reveal a hadron to quark-gluon plasma (QGP) phase transition. The K+ yield is found to grow proportional to the number of participating ('wounded') nucleons N, above N=100. Previous NA52 data agree with the above finding and show a discontinuous behaviour in the kaon centrality dependence near N=100, marking the onset of strangeness enhancement -over e.g. p+A data at the same \\sqrt{s}- in a chemically equilibrated phase.

  5. Room temperature lasing in GeSn alloys: A path to CMOS-compatible infrared lasers

    Science.gov (United States)

    Li, Zairui; Zhao, Yun; Gallagher, James; Menéndez, José; Kouvetakis, John; Agha, Imad; Mathews, Jay

    The semiconductor industry has been pushing silicon photonics development for many years, resulting in the realization of many CMOS-compatible optoelectronic devices. However, one challenge that has not been overcome is the development of Si-based lasers. Recently, GeSn alloys grown on Si have shown much promise in the field of infrared optoelectronics. These alloy films are compatible with CMOS processing, have band gaps in the infrared, and the band structure of GeSn can be tuned via Sn concentration to induce direct band gap emission. In this work, we report on room temperature lasing in optically-pumped waveguides fabricated from GeSn films grown epitaxially on Si(100) substrates. The waveguides were defined using standard UV photolithography and dry-etched in a Cl plasma. The end facets were mirror polished, and Al was deposited on one facet to enhance cavity quality. The waveguides were optically-pumped using a 976nm wavelength solid-state laser, and the corresponding emission was measured. The dependence of the emission power on the pump power shows a clear transition between spontaneous and stimulated emission, thereby demonstrating room temperature lasing.

  6. Monopole giant resonance in $^{100-132}$Sn, $^{144}$Sm and $^{208}$Pb

    CERN Document Server

    Kvasil, J; Repko, A; Reinhard, P -G; Nesterenko, V O; Kleinig, W

    2014-01-01

    The isoscalar giant monopole resonance (GMR) in spherical nuclei $^{100-132}$Sn, $^{144}$Sm, and $^{208}$Pb is investigated within the Skyrme random-phase-approximation (RPA) for a variety of Skyrme forces and different pairing options. The calculated GMR strength functions are directly compared to the available experimental distributions. It is shown that, in accordance to results of other groups, description of GMR in Sn and heavier Sm/Pb nuclei needs different values of the nuclear incompressibilty, $K \\approx$ 200 or 230 MeV, respectively. Thus none from the used Skyrme forces is able to describe GMR in these nuclei simultaneously. The GMR peak energy in open-shell $^{120}$Sn is found to depend on the isoscalar effective mass, which might be partly used for a solution of the above problem. Some important aspects of the problem (discrepancies of available experimental data, proper treatment of the volume and surface compression in finite nuclei, etc) are briefly discussed.

  7. Comparative studies of band structures for biaxial (100)-, (110)-, and (111)-strained GeSn: A first-principles calculation with GGA+U approach

    Science.gov (United States)

    Huang, Wenqi; Cheng, Buwen; Xue, Chunlai; Liu, Zhi

    2015-10-01

    Experiments and calculations performed in previous studies indicate that compressive strain will increase (100)-strained GeSn's need for Sn to realize a direct bandgap when it is pseudomorphically grown on Ge buffers. To eliminate this negative effect, we systematically investigate the band structures of biaxial (100)-, (110)-, and (111)-strained GeSn using a first-principle calculation combined with supercell models and the GGA+U approach. This method has proven to be efficient and accurate for calculating the properties of GeSn. The calculated lattice constants and elastic constants of Ge and Sn are in good agreement with the experimental results. The crossover value of Sn concentration which is required to change the bandgap of unstrained GeSn from indirect to direct is found to be 8.5%, which is very close to the recent experimental result of 9%. The calculated bandgaps of strained GeSn show that the moving rate of the Γ valley is higher than those of the L and X valleys in (100)- and (110)-strained GeSn. However, the moving rate of the L valley is higher than those of Γ and X valleys in (111)-strained GeSn. Tensile strain has a positive effect on the transition of (100)- and (110)-strained GeSn, changing the bandgap from indirect to direct, whereas compressive strain has a positive effect for (111)-strained GeSn. The use of the (111) orientation can reduce GeSn's need for Sn and greatly increase the energy difference between the L valley and Γ valley. Thus, for strained GeSn grown on Ge buffers, the (111) orientation is a good choice to take advantage of compressive strain.

  8. High transverse mass pion and proton correlations in central PbPb collisions at 17GeV/nucleon

    CERN Document Server

    Bearden, I G; Boissevain, J G; Christiansen, P H L; Conin, L; Dodd, J; Erazmus, B; Esumi, S; Fabjan, Christian Wolfgang; Ferenc, D; Franz, A; Gaardhøje, J J; Hansen, A G; Hansen, O; Hardtke, D; van Hecke, H; Holzer, E B; Humanic, T J; Hummel, P; Jacak, B V; Kaimi, K; Kaneta, M; Kohama, T; Kopytine, M; Leltchouk, M; Ljubicic, A; Lörstad, B; Maeda, N; Martin, L; Medvedev, A; Murray, M; Ohnishi, H; Paic, G; Pandey, S U; Piuz, François; Pluta, J; Polychronakos, V; Potekhin, M V; Poulard, G; Reichhold, D M; Sakaguchi, A; Schmidt-Sørensen, J; Simon-Gillo, J; Sondheim, W E; Sugitate, T; Sullivan, J P; Sumi, Y; Willis, W J; Wolf, K; Xu, N; Zachary, D S

    2003-01-01

    For central PbPb collisions at a center of mass energy of 17.3 GeV/nucleon we have made the first two-dimensional measurement of the pp correlation function. These data extend the range of previous studies of HBT radii by a factor of two in transverse mass. They are consistent with a hydrodynamic interpretation and microscopic models that include hadronic rescattering and transverse expansion. We also report new data on pion correlations. The two particle correlations of negative pions at a transverse mass of 0.92 GeV imply source radii that are smaller than typical hydrodynamic fits and transport model simulations. It is possible that these fast pions may have left the source before the build up of hydrodynamic flow.

  9. Proton - Lambda Correlations in Central Pb+Pb Collisions at $\\sqrt{s_{NN}}$ = 17.3 GeV

    CERN Document Server

    Anticic, T; Barna, D; Bartke, J; Beck, H; Betev, L; Bialkowska, H; Blume, C; Bogusz, M; Boimska, B; Book, J; Botje, M; Buncic, P; Cetner, T; Christakoglou, P; Chung, P; Chvala, O; Cramer, J; Eckardt, V; Fodor, Z; Foka, P; Friese, V; Gazdzicki, M; Grebieszkow, K; Hohne, C; Kadija, K; Karev, A; Kolesnikov, V; Kowalski, M; Kresan, D; Laszlo, A; Lacey, R; van Leeuwen, M; Mackowiak, M K; Makariev, M; Malakhov, A; Mateev, M; Melkumov, G; Mitrovski, M; Mrowczynski, St; Nicolic, V; Palla, G; Panagiotou, A; Peryt, W; Pluta, J; Prindle, D; Puhlhofer, F; Renfordt, R; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Schuster, T; Seyboth, P; Sikler, F; Skrzypczak, E; Slodkowski, M; Stefanek, G; Stock, R; Strobele, H; Susa, T; Szuba, M; Utvic, M; Varga, D; Vassiliou, M; Veres, G; Vesztergombi, G; Vranic, D; Wlodarczyk, Z; Wojtaszek-Szwarc, A

    2011-01-01

    The momentum correlation between protons and lambda particles emitted from central Pb+Pb collisions at sqrt(s_{NN}) = 17.3 GeV was studied by the NA49 experiment at the CERN SPS. A clear enhancement is observed for small relative momenta (q_{inv} < 0.2 GeV). By fitting a theoretical model, which uses the strong interaction between the proton and the lambda in a given pair, to the measured data a value for the effective source size is deduced. Assuming a static Gaussian source distribution we derive an effective radius parameter of R_G = 3.02 \\pm 0.20$(stat.)^{+0.44}_{-0.16}(syst.) fm.

  10. Interband interaction between bulk and surface resonance bands of a Pb-adsorbed Ge(001) surface

    Science.gov (United States)

    Sakata, Tomohiro; Takeda, Sakura N.; Kitagawa, Kosuke; Daimon, Hiroshi

    2016-08-01

    We investigated the valence band structure of a Pb-adsorbed Ge(001) surface by angle-resolved photoelectron spectroscopy. Three Ge bands, G1, G2, and G3, were observed in a Ge(001) 2 × 1 clean surface. In addition to these three bands, a fourth band (R band) is found on the surface with 2 ML of Pb. The R band continuously appeared even when the surface superstructure was changed. The position of the R band does not depend on Pb coverage. These results indicate that the R band derives from Ge subsurface states, known as surface resonance states. Furthermore, the effective mass of G3 is significantly reduced when the R band exists. We found that this reduction of G3 effective mass was explained by the interaction of the G3 and R bands. Consequently, the surface resonance band is considered to penetrate into the Ge subsurface region affecting the Ge bulk states. We determine the hybridization energy to be 0.068 eV by fitting the observed bands.

  11. 2D Tl-Pb compounds on Ge(1 1 1) surface: atomic arrangement and electronic band structure.

    Science.gov (United States)

    Gruznev, D V; Bondarenko, L V; Tupchaya, A Y; Eremeev, S V; Mihalyuk, A N; Chou, J P; Wei, C M; Zotov, A V; Saranin, A A

    2017-01-25

    Structural transformations and evolution of the electron band structure in the (Tl, Pb)/Ge(1 1 1) system have been studied using low-energy electron diffraction, scanning tunneling microscopy, angle-resolved photoelectron spectroscopy and density functional theory calculations. The two 2D Tl-Pb compounds on Ge(1 1 1), [Formula: see text]-(Tl, Pb) and [Formula: see text]-(Tl, Pb), have been found and their composition, atomic arrangement and electron properties has been characterized. The (Tl, Pb)/Ge(1 1 1)[Formula: see text] compound is almost identical to the alike (Tl, Pb)/Si(1 1 1)[Formula: see text] system from the viewpoint of its atomic structure and electronic properties. They contain 1.0 ML of Tl atoms arranged into a honeycomb network of chained trimers and 1/3 ML of Pb atoms occupying the centers of the honeycomb units. The (Tl, Pb)/Ge(1 1 1)[Formula: see text] compound contains six Tl atoms and seven Pb atoms per [Formula: see text] unit cell (i.e.  ∼0.67 ML Tl and  ∼0.78 ML Pb). Its atomic structure can be visualized as consisting of Pb hexagons surrounded by Tl trimers. The (Tl, Pb)/Ge(1 1 1)[Formula: see text] and (Tl, Pb)/Ge(1 1 1)[Formula: see text] compounds are metallic and their band structures contain spin-split surface-state bands. By analogy with the (Tl, Pb)/Si(1 1 1)[Formula: see text], these (Tl, Pb)/Ge(1 1 1) compounds are believed to be promising objects for prospective studies of superconductivity in one-atom-layer systems.

  12. 2D Tl-Pb compounds on Ge(1 1 1) surface: atomic arrangement and electronic band structure

    Science.gov (United States)

    Gruznev, D. V.; Bondarenko, L. V.; Tupchaya, A. Y.; Eremeev, S. V.; Mihalyuk, A. N.; Chou, J. P.; Wei, C. M.; Zotov, A. V.; Saranin, A. A.

    2017-01-01

    Structural transformations and evolution of the electron band structure in the (Tl, Pb)/Ge(1 1 1) system have been studied using low-energy electron diffraction, scanning tunneling microscopy, angle-resolved photoelectron spectroscopy and density functional theory calculations. The two 2D Tl-Pb compounds on Ge(1 1 1), \\sqrt{3}× \\sqrt{3} -(Tl, Pb) and 3× 3 -(Tl, Pb), have been found and their composition, atomic arrangement and electron properties has been characterized. The (Tl, Pb)/Ge(1 1 1)\\sqrt{3}× \\sqrt{3} compound is almost identical to the alike (Tl, Pb)/Si(1 1 1)\\sqrt{3}× \\sqrt{3} system from the viewpoint of its atomic structure and electronic properties. They contain 1.0 ML of Tl atoms arranged into a honeycomb network of chained trimers and 1/3 ML of Pb atoms occupying the centers of the honeycomb units. The (Tl, Pb)/Ge(1 1 1)3× 3 compound contains six Tl atoms and seven Pb atoms per 3× 3 unit cell (i.e.  ˜0.67 ML Tl and  ˜0.78 ML Pb). Its atomic structure can be visualized as consisting of Pb hexagons surrounded by Tl trimers. The (Tl, Pb)/Ge(1 1 1)\\sqrt{3}× \\sqrt{3} and (Tl, Pb)/Ge(1 1 1)3× 3 compounds are metallic and their band structures contain spin-split surface-state bands. By analogy with the (Tl, Pb)/Si(1 1 1)\\sqrt{3}× \\sqrt{3} , these (Tl, Pb)/Ge(1 1 1) compounds are believed to be promising objects for prospective studies of superconductivity in one-atom-layer systems.

  13. Epitaxial GeSn film formed by solid phase epitaxy and its application to Yb{sub 2}O{sub 3}-gated GeSn metal-oxide-semiconductor capacitors with sub-nm equivalent oxide thickness

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ching-Wei; Wu, Yung-Hsien; Hsieh, Ching-Heng; Lin, Chia-Chun [Department of Engineering and System Science, National Tsing Hua University, 300 Hsinchu, Taiwan (China)

    2014-11-17

    Through the technique of solid phase epitaxy (SPE), an epitaxial Ge{sub 0.955}Sn{sub 0.045} film was formed on a Ge substrate by depositing an amorphous GeSn film followed by a rapid thermal annealing at 550 °C. A process that uses a SiO{sub 2} capping layer on the amorphous GeSn film during SPE was proposed and it prevents Sn precipitation from occurring while maintaining a smooth surface due to the reduced surface mobility of Sn atoms. The high-quality epitaxial GeSn film was observed to have single crystal structure, uniform thickness and composition, and tiny surface roughness with root mean square of 0.56 nm. With a SnO{sub x}-free surface, Yb{sub 2}O{sub 3}-gated GeSn metal-oxide-semiconductor (MOS) capacitors with equivalent oxide thickness (EOT) of 0.55 nm were developed. A small amount of traps inside the Yb{sub 2}O{sub 3} was verified by negligible hysteresis in capacitance measurement. Low leakage current of 0.4 A/cm{sup 2} at gate bias of flatband voltage (V{sub FB})-1 V suggests the high quality of the gate dielectric. In addition, the feasibility of using Yb{sub 2}O{sub 3} to well passivate GeSn surface was also evidenced by the small interface trap density (D{sub it}) of 4.02 × 10{sup 11} eV{sup −1} cm{sup −2}, which can be attributed to smooth GeSn surface and Yb{sub 2}O{sub 3} valency passivation. Both leakage current and D{sub it} performance outperform other passivation techniques at sub-nm EOT regime. The proposed epitaxial GeSn film along with Yb{sub 2}O{sub 3} dielectric paves an alternative way to enable high-performance GeSn MOS devices.

  14. Ge2Sb2Te5/SnSe2 nanocomposite multilayer thin films for phase change memory application

    Science.gov (United States)

    Feng, Xiaoyi; Wen, Ting; Zhai, Jiwei; Lai, Tianshu; Wang, Changzhou; Song, Sannian; Song, Zhitang

    2014-10-01

    By nanocompositing Ge2Sb2Te5 and SnSe2, the electrical and thermal proprieties of Ge2Sb2Te5/SnSe2 multilayer films for phase change random access memory (PCRAM) are better than those of Ge2Sb2Te5 films. The crystallization temperature rises and can be controlled. The resistance gap can reach approximately five orders of magnitude to ensure high data reliability. The activity energy (Ea) is more than 2.60 eV and the temperature for 10 year data retention reach 110 °C. The analysis of both XRD patterns and TEM images confirmed the reversible phase change transition between amorphous and crystalline state in Ge2Sb2Te5/SnSe2 nanocomposite multilayer films. According to transient photoreflectance traces, the speed of crystallization process was about 33 ns. Among different Ge2Sb2Te5/SnSe2 multilayer films, the film constitute of [Ge2Sb2Te5 (4 nm)/SnSe2(10 nm)]7 showed better properties and was manufactured by CMOS technology to phase change memory (PCM) cells. This result revealed that the Ge2Sb2Te5/SnSe2 nanocomposite multilayer film is a promising phase change material.

  15. Microstructural and Hardness Evaluations of a Centrifuged Sn-22Pb Casting Alloy Compared with a Lead-Free SnAg Alloy

    Science.gov (United States)

    Satizabal, Luz Myrian; Costa, Diego; Hainick, Guilherme Ottamr; Moura, Diego Rodrigo; Bortolozo, Ausdinir Danilo; Osório, Wislei Riuper

    2017-01-01

    A great preoccupation with replacing the traditional Sn-Pb alloy with a Pb-free alloy ("green alloy") is recognized. There are industrial sectors that demand metallurgical improvements to attain certain unsoundness and adequate properties as a function of imposed operational parameters. In this experimental investigation, two distinctive centrifuged casting alloys (i.e., Sn-2 wt pct Ag and Sn-22 wt pct Pb) are compared. It is found that centrifuged castings have similar microstructure constituents, although distinctive cooling rates and solute contents are considered. It is also found that Ag3Sn intermetallic particles are responsible for attaining similar tensile strength, since more dislocations between Ag3Sn particles and the Sn-rich phase are provided. In order to replace the Sn-Pb alloys with a successor alloy containing sustainability and environmental aspects associated with castability and to guarantee the desired properties, it seems that a green alloy (Pb free) with intermetallic particles finely and homogeneously distributed provides an interesting benefit to various industrial applications.

  16. Microstructural and Hardness Evaluations of a Centrifuged Sn-22Pb Casting Alloy Compared with a Lead-Free SnAg Alloy

    Science.gov (United States)

    Satizabal, Luz Myrian; Costa, Diego; Hainick, Guilherme Ottamr; Moura, Diego Rodrigo; Bortolozo, Ausdinir Danilo; Osório, Wislei Riuper

    2017-04-01

    A great preoccupation with replacing the traditional Sn-Pb alloy with a Pb-free alloy ("green alloy") is recognized. There are industrial sectors that demand metallurgical improvements to attain certain unsoundness and adequate properties as a function of imposed operational parameters. In this experimental investigation, two distinctive centrifuged casting alloys ( i.e., Sn-2 wt pct Ag and Sn-22 wt pct Pb) are compared. It is found that centrifuged castings have similar microstructure constituents, although distinctive cooling rates and solute contents are considered. It is also found that Ag3Sn intermetallic particles are responsible for attaining similar tensile strength, since more dislocations between Ag3Sn particles and the Sn-rich phase are provided. In order to replace the Sn-Pb alloys with a successor alloy containing sustainability and environmental aspects associated with castability and to guarantee the desired properties, it seems that a green alloy (Pb free) with intermetallic particles finely and homogeneously distributed provides an interesting benefit to various industrial applications.

  17. Theoretical Electric Dipole Moments of SiH, GeH and SnH

    Science.gov (United States)

    Pettersson, Lars G. M.; Langhoff, Stephen R.

    1986-01-01

    Accurate theoretical dipole moments (mu(sub c) have been computed for the X(exp 2)Pi ground states of Si(-)H(+)(0.118 D), Ge(+)H(-)(0.085 D) and Sn(+)H(-)(0.357 D). The trend down the periodic table is regular and follows that expected from the electronegativities of the group IV atoms. The dipole moment of 1.24 +/- 0.1 D for GeH recently derived by Brown, Evenson and Sears from the relative intensities of electric and magnetic dipole transitions in the 10 microns spectrum of the X(exp 2)Pi state is seriously questioned.

  18. Electrical characteristics of Ni Ohmic contact on n-type GeSn

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.; Cheng, H. H., E-mail: hhcheng@ntu.edu.tw [Center for Condensed Matter Sciences and Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 106, Taiwan (China); Lee, L. C.; Lee, C. P. [Center for Nano Science and Technology, National Chiao Tung University, Hsinchu 300, Taiwan (China); Su, L. H.; Suen, Y. W. [Department of Physics and Institute of Nano Science, National Chung Hsing University, Taichung 402, Taiwan (China)

    2014-06-16

    We report an investigation of the electrical and material characteristics of Ni on an n-type GeSn film under thermal annealing. The current-voltage traces measured with the transmission line method are linear for a wide range of annealing temperatures. The specific contact resistivity was found to decrease with increasing annealing temperature, followed by an increase as the annealing temperature further increased, with a minimum value at an annealing temperature of 350 °C. The material characteristics at the interface layer were measured by energy-dispersive spectrometer, showing that an atomic ratio of (Ni)/(GeSn) = 1:1 yields the lowest specific contact resistivity.

  19. A microstructural study of creep and thermal fatigue deformation in 60Sn-40Pb solder joints

    Energy Technology Data Exchange (ETDEWEB)

    Tribula, D.

    1990-06-02

    Thermal fatigue failures of solder joints in electronic devices often arise from cyclic shear strains imposed by the mismatched thermal expansion coefficients of the materials that bind the joint as temperature changes are encountered. Increased solder joint reliability demands a fundamental understanding of the metallurigical mechanisms that control the fatigue to design accurate accelerated probative tests and new, more fatigue resistant solder alloys. The high temperatures and slow strain rates that pertain to thermal fatigue imply that creep is an important deformation mode in the thermal fatigue cycle. In this work, the creep behaviour of a solder joint is studied to determine the solder's microstructural response to this type of deformation and to relate this to the more complex problem of thermal fatigue. It is shown that creep failures arise from the inherent inhomogeneity and instability of the solder microstructure and suggest that small compositional changes of the binary near-eutectic Pn-Sn alloy may defeat the observed failure mechanisms. This work presents creep and thermal fatigue data for several near-eutectic Pb-Sn solder compositions and concludes that a 58Sn-40Pb-2In and a 58Sn-40Pb-2Cd alloy show significantly enhanced fatigue resistance over that of the simple binary material. 80 refs., 33 figs., 1 tab.

  20. Thermophysical Properties of Sn-Ag-Cu Based Pb-Free Solders

    Science.gov (United States)

    Kim, Sok Won; Lee, Jaeran; Jeon, Bo-Min; Jung, Eun; Lee, Sang Hyun; Kang, Kweon Ho; Lim, Kwon Taek

    2009-06-01

    Lead-tin (Pb-Sn) alloys are the dominant solders used for electronic packaging because of their low cost and superior properties required for interconnecting electronic components. However, increasing environmental and health concerns over the toxicity of lead, combined with global legislation to limit the use of Pb in manufactured products, have led to extensive research and development studies of lead-free solders. The Sn-Ag-Cu ternary eutectic alloy is considered to be one of the promising alternatives. Except for thermal properties, much research on several properties of Sn-Ag-Cu alloy has been performed. In this study, five Sn-xAg-0.5Cu alloys with variations of Ag content x of 1.0 mass%, 2.5 mass%, 3.0 mass%, 3.5 mass%, and 4.0 mass% were prepared, and their thermal diffusivity and specific heat were measured from room temperature to 150 °C, and the thermal conductivity was calculated using the measured thermal diffusivity, specific heat, and density values. Also, the linear thermal expansion was measured from room temperature to 170 °C. The results show that Sn-3.5Ag-0.5Cu is the best candidate because it has a maximum thermal conductivity and a low thermal expansion, which are the ideal conditions to be a proper packaging alloy for effective cooling and thermostability.

  1. Ellipsometric characterization of doped Ge0.95Sn0.05 films in the infrared range for plasmonic applications.

    Science.gov (United States)

    Augel, L; Fischer, I A; Hornung, F; Dressel, M; Berrier, A; Oehme, M; Schulze, J

    2016-09-15

    GeSn as a group-IV material opens up new possibilities for realizing photonic device concepts in Si-compatible fabrication processes. Here we present results of the ellipsometric characterization of highly p- and n-type doped Ge0.95Sn0.05 alloys deposited on Si substrates investigated in the wavelength range from 1 to 16 μm. We discuss the suitability of these films for integrated plasmonic applications in the infrared region.

  2. Mixed Ge/Pb perovskite light absorbers with an ascendant efficiency explored from theoretical view.

    Science.gov (United States)

    Sun, Ping-Ping; Li, Quan-Song; Feng, Shuai; Li, Ze-Sheng

    2016-06-07

    Organic-inorganic methylammonium lead halide perovskites have recently attracted great interest emerging as promising photovoltaic materials with a high 20.8% efficiency, but lead pollution is still a problem that may hinder the development and wide spread of MAPbI3 perovskites. To reduce the use of lead, we investigated the structures, electronic and optical properties of mixed MAGexPb(1-x)I3 theoretically by using density functional theory methods at different calculation levels. Results show that the mixed Ge/Pb perovskites exhibit a monotonic decrease evolution in band energy to push the band gap deeper in the near-infrared region and have a red shift optical absorption with an increased proportion of Ge. The results also indicate that lattice distortion and spin-orbit coupling (SOC) strength play important roles in the band gap behavior of MAGexPb(1-x)I3 by affecting the bandwidths of CBM and VBM. The calculations for short circuit current density, open circuit voltage, and theoretical power conversion efficiency suggest that mixed Ge/Pb perovskite solar cells (PSCs) with efficiency over 22% are superior to MAPbI3 and MAGeI3. And notably, MAGe0.75Pb0.25I3 is a promising harmless material for solar cells absorber with the highest theoretical efficiency of 24.24%. These findings are expected to be helpful for further rational design of nontoxic light absorption layer for high-performance PSCs.

  3. Core-shell PbS/Sn:In2O3 and branched PbIn2S4/Sn:In2O3 nanowires in quantum dot sensitized solar cells

    Science.gov (United States)

    Zervos, Matthew; Vasile, Eugenia; Vasile, Eugeniu; Othonos, Andreas

    2017-02-01

    Core-shell PbS/Sn:In2O3 and branched PbIn2S4/Sn:In2O3 nanowires have been obtained via the deposition of Pb over Sn:In2O3 nanowires and post growth processing under H2S between 100 °C-200 °C and 300 °C-500 °C respectively. The PbS/Sn:In2O3 nanowires have diameters of 50-250 nm and consist of cubic PbS and In2O3 while the PbIn2S4/Sn:In2O3 nanowires consist of PbIn2S4 branches with diameters of 10-30 nm and an orthorhombic crystal structure. We discuss the growth mechanisms and also show that the density of electrons in the n-type Sn:In2O3 core is strongly dependent on the thickness of the p-type PbS shell, which must be smaller than 30 nm to prevent core depletion, via the self-consistent solution of the Poisson-Schrödinger equations in the effective mass approximation. The PbS/Sn:In2O3 and PbIn2S4/Sn:In2O3 nanowire networks had resistances of 100-200 Ω due to the large carrier densities and exhibited defect related photoluminescence at 2.2 eV and 1.5 eV respectively. We show that PbS in contact with polysulfide electrolyte has ohmic like behavior but the PbS/Sn:In2O3 nanowires gave, rectifying current voltage characteristics as a counter electrode in a quantum dot sensitized solar cell using a conventional ITO/TiO2/CdS/CdSe photo anode, an open circuit voltage of ≈0.5 V, and short circuit current density of ≈1 mA cm-2. In contrast the branched PbIn2S4/Sn:In2O3 nanowires exhibited a higher current carrying capability of ≈7 mA cm-2 and higher power conversion efficiency of ≈2%.

  4. Ultra-low temperature (≤300 °C) growth of Ge-rich SiGe by solid-liquid-coexisting annealing of a-GeSn/c-Si structures

    Science.gov (United States)

    Sadoh, Taizoh; Chikita, Hironori; Matsumura, Ryo; Miyao, Masanobu

    2015-09-01

    Ultra-low temperature (≤300 °C) growth of Ge-rich SiGe on Si substrates is strongly desired to realize advanced electronic and optical devices, which can be merged onto Si large-scale integrated circuits (LSI). To achieve this, annealing characteristics of a-GeSn/c-Si structures are investigated under wide ranges of the initial Sn concentrations (0%-26%) and annealing conditions (300-1000 °C, 1 s-48 h). Epitaxial growth triggered by SiGe mixing is observed after annealing, where the annealing temperatures necessary for epitaxial growth significantly decrease with increasing initial Sn concentration and/or annealing time. As a result, Ge-rich (˜80%) SiGe layers with Sn concentrations of ˜2% are realized by ultra-low temperature annealing (300 °C, 48 h) for a sample with the initial Sn concentration of 26%. The annealing temperature (300 °C) is in the solid-liquid coexisting temperature region of the phase diagram for Ge-Sn system. From detailed analysis of crystallization characteristics and composition profiles in grown layers, it is suggested that SiGe mixing is generated by a liquid-phase reaction even at ultra-low temperatures far below the melting temperature of a-GeSn. This ultra-low-temperature growth technique of Ge-rich SiGe on Si substrates is expected to be useful to realize next-generation LSI, where various multi-functional devices are integrated on Si substrates.

  5. Ultra-low temperature (≤300 °C) growth of Ge-rich SiGe by solid-liquid-coexisting annealing of a-GeSn/c-Si structures

    Energy Technology Data Exchange (ETDEWEB)

    Sadoh, Taizoh, E-mail: sadoh@ed.kyushu-u.ac.jp; Chikita, Hironori; Miyao, Masanobu [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Matsumura, Ryo [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); JSPS Research Fellow, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan)

    2015-09-07

    Ultra-low temperature (≤300 °C) growth of Ge-rich SiGe on Si substrates is strongly desired to realize advanced electronic and optical devices, which can be merged onto Si large-scale integrated circuits (LSI). To achieve this, annealing characteristics of a-GeSn/c-Si structures are investigated under wide ranges of the initial Sn concentrations (0%–26%) and annealing conditions (300–1000 °C, 1 s–48 h). Epitaxial growth triggered by SiGe mixing is observed after annealing, where the annealing temperatures necessary for epitaxial growth significantly decrease with increasing initial Sn concentration and/or annealing time. As a result, Ge-rich (∼80%) SiGe layers with Sn concentrations of ∼2% are realized by ultra-low temperature annealing (300 °C, 48 h) for a sample with the initial Sn concentration of 26%. The annealing temperature (300 °C) is in the solid-liquid coexisting temperature region of the phase diagram for Ge-Sn system. From detailed analysis of crystallization characteristics and composition profiles in grown layers, it is suggested that SiGe mixing is generated by a liquid-phase reaction even at ultra-low temperatures far below the melting temperature of a-GeSn. This ultra-low-temperature growth technique of Ge-rich SiGe on Si substrates is expected to be useful to realize next-generation LSI, where various multi-functional devices are integrated on Si substrates.

  6. Stable Low-Bandgap Pb-Sn Binary Perovskites for Tandem Solar Cells.

    Science.gov (United States)

    Yang, Zhibin; Rajagopal, Adharsh; Chueh, Chu-Chen; Jo, Sae Byeok; Liu, Bo; Zhao, Ting; Jen, Alex K-Y

    2016-10-01

    A low-bandgap (1.33 eV) Sn-based MA0.5 FA0.5 Pb0.75 Sn0.25 I3 perovskite is developed via combined compositional, process, and interfacial engineering. It can deliver a high power conversion efficiency (PCE) of 14.19%. Finally, a four-terminal all-perovskite tandem solar cell is demonstrated by combining this low-bandgap cell with a semitransparent MAPbI3 cell to achieve a high efficiency of 19.08%. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Effects of Sn Substitution on Thermoelectric Properties of Ge4SbTe5

    Science.gov (United States)

    Williams, Jared B.; Mather, Spencer; Morelli, Donald T.

    2016-02-01

    Phase-change materials are identified by their ability to rapidly alternate between amorphous and crystalline phases upon heating, exhibiting large contrast in the optical/electrical properties of the respective phases. Such materials are primarily used in memory storage applications, but recently they have also been identified as potential thermoelectric materials. Many of the phase-change materials studied today can be found on the pseudobinary (GeTe)1- x (Sb2Te3) x tie-line. Ge4SbTe5, a single-phase compound just off of the (GeTe)1- x (Sb2Te3) x tie-line, forms in a metastable rocksalt crystal structure at room temperature. It has been found that stoichiometric and undoped Ge4SbTe5 exhibits thermal conductivity of ~1.2 W/m-K at high temperature and a dramatic decrease in electrical resistivity at 623 K due to a structural phase transition, which leads to a large enhancement in both thermoelectric power factor and thermoelectric figure of merit at 823 K. Introducing point defects via isoelectronic substitutions can be an effective means of reducing thermal conductivity and enhancing thermoelectric performance. We present a study of the effects of Sn substitution for Ge on the electrical and thermal transport properties of Ge4SbTe5.

  8. Study of projectile fragmentation in the reaction (158 A GeV) Pb + Pb using CR-39

    CERN Document Server

    Qureshi, I E; Javed, M T; Manzoor, S; Sher, G; Aleem, F; Khan, H A

    2005-01-01

    The fragmentation of Pb ions at 158 A GeV energy produced in the interaction with Pb target has been studied using a CR-39 track detector. A stack comprising of 64 detectors was prepared such that a target of 1 cm thickness was sandwiched between the sheets of CR-39. The purpose of this exposure geometry was to calibrate CR-39 with respect to relativistic heavy ions as well as to study the fragmentation of Pb ions at 158 A GeV energy. The exposure was carried out at the SPS beam facility of CERN at normal incidence with a fluence of . Two detectors from the exposed stack have been selected for this study: one before and the other after the target material. After etching, the detectors were scanned using an optical microscope and the etched track lengths and the diameters of the track openings were measured manually. Considering that the lengths of tracks provide the best charge resolution for Z>65, we have measured track lengths for a sufficiently large number of fragments to identify individual charge states...

  9. Migration of Sn and Pb from Solder Ribbon onto Ag Fingers in Field-Aged Silicon Photovoltaic Modules

    Directory of Open Access Journals (Sweden)

    Wonwook Oh

    2015-01-01

    Full Text Available We investigated the migration of Sn and Pb onto the Ag fingers of crystalline Si solar cells in photovoltaic modules aged in field for 6 years. Layers of Sn and Pb were found on the Ag fingers down to the edge of the solar cells. This phenomenon is not observed in a standard acceleration test condition for PV modules. In contrast to the acceleration test conditions, field aging subjects the PV modules to solar irradiation and moisture condensation at the interface between the solar cells and the encapsulant. The solder ribbon releases Sn and Pb via repeated galvanic corrosion and the Sn and Pb precipitate on Ag fingers due to the light-induced plating under solar irradiation.

  10. Raman scattering from Ge{sub 1-x}Sn{sub x} (x ≤ 0.14) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Navarro C, H.; Rodriguez, A. G.; Vidal, M. A. [Universidad Autonoma de San Luis Potosi, Coordinacion para la Innovacion y la Aplicacion de la Ciencia y la Tecnologia, Alvaro Obregon No. 64, 78000 San Luis Potosi, S. L. P. (Mexico); Perez Ladron de G, H. [Universidad de Guadalajara, Centro Universitario de los Lagos, Av. Enrique Diaz de Leon No. 1144, Col. Paseos de la Montana, 47460 Lagos de Moreno, Jalisco (Mexico)

    2015-07-01

    Ge{sub 1-x}Sn{sub x} alloys with x concentration up to 0.14 were grown on Ge(001) and GaAs(001) substrates in a conventional R. F. Magnetron Sputtering system at low substrate temperatures. The structural characteristics of these alloys were studied for different Sn concentrations between 1 to 14% by high resolution X-ray diffraction, and Raman spectroscopy. Contrasting characteristics of the grown layers are observed if the Sn concentration is larger or smaller than 6% as revealed by X-ray diffraction and Raman spectroscopy. (Author)

  11. Large grain growth of Ge-rich Ge{sub 1−x}Sn{sub x} (x ≈ 0.02) on insulating surfaces using pulsed laser annealing in flowing water

    Energy Technology Data Exchange (ETDEWEB)

    Kurosawa, Masashi, E-mail: kurosawa@alice.xtal.nagoya-u.ac.jp [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); JSPS, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Taoka, Noriyuki; Nakatsuka, Osamu; Zaima, Shigeaki [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Ikenoue, Hiroshi [Graduate School of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan)

    2014-02-10

    We investigate Sn incorporation effects on the growth characteristics of Ge-rich Ge{sub 1−x}Sn{sub x} (x < 0.02) on SiO{sub 2} crystallized by pulsed laser annealing (PLA) in air and water. Despite the very low Sn content of 2%, Sn atoms within the GeSn layers play a role in preventing ablation and aggregation of the layers during these PLA. Raman and electron backscatter diffraction measurements demonstrate achievement of large-grain (∼800 nmϕ) growth of Ge{sub 0.98}Sn{sub 0.02} polycrystals by using PLA in water. These polycrystals also show a tensile-strain of ∼0.68%. This result opens up the possibility for developing GeSn-based devices fabricated on flexible substrates as well as Si platforms.

  12. 158A GeV/c Pb+Pb碰撞可能有QGP的一旁证%A Circumstantial Evidence for the Possible Production of QGP in the 158A GeV/c Central Pb+Pb Collisions

    Institute of Scientific and Technical Information of China (English)

    刘志毅; 萨本豪; 周书华

    2001-01-01

    用不含QGP假设的强子和弦级联模型(JPCIAE),研究了CERN WA98实验组新近发表的158A GeV/c Pb+Pb中心碰撞中直接光子和π0粒子的横动量分布:两者的理论结果均一致的低于实验值. 联系到JPCIAE能成功解释无直接光子超出确切迹象的WA80和WA93对200A GeV/c S+Au中心碰撞测量得出的结果:因而为158A GeV/c Pb+Pb中心碰撞中可能有QGP生成提供了一个旁证.

  13. Theoretical investigation of tensile strained GeSn waveguide with Si₃N₄ liner stressor for mid-infrared detector and modulator applications.

    Science.gov (United States)

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

    2015-03-23

    We theoretically investigate a tensile strained GeSn waveguide integrated with Si₃N₄ liner stressor for the applications in mid-infrared (MIR) detector and modulator. A substantial tensile strain is induced in a 1 × 1 μm² GeSn waveguide by the expansion of 500 nm Si₃N₄ liner stressor and the contour plots of strain are simulated by the finite element simulation. Under the tensile strain, the direct bandgap E(G,Γ) of GeSn is significantly reduced by lowering the Γ conduction valley in energy and lifting of degeneracy of valence bands. Absorption coefficients of tensile strained GeSn waveguides with different Sn compositions are calculated. As the Si₃N₄ liner stressor expands by 1%, the cut-off wavelengths of tensile strained Ge(0.97)Sn(0.03), Ge(0.95)Sn(0.05), and Ge(0.90)Sn(0.10) waveguide photodetectors are extended to 2.32, 2.69, and 4.06 μm, respectively. Tensile strained Ge(0.90)Sn(0.10) waveguide electro-absorption modulator based on Franz-Keldysh (FK) effect is demonstrated in theory. External electric field dependence of cut-off wavelength and propagation loss of tensile strained Ge(0.90)Sn(0.10) waveguide is observed, due to the FK effect.

  14. The correlation of electrical conductivity with the microstructure of Ge2Sb2Te5 thin films alloyed with Sn

    Science.gov (United States)

    Yin, Qixun; Chen, Leng

    2017-01-01

    In this research, the effects of Sn alloying on structure transformation and electrical characteristics of Ge2Sb2Te5 (GST) thin films were studied. It was discovered that the SnTe phase formed in GST thin films when Sn content exceeded 26 at%, and the addition of Sn atoms expanded the lattice parameter, as a result of atomic radii difference between Ge and Sn atoms. Furthermore, temperature dependent sheet resistance measurements on the GST:Sn thin films were performed for the electrical characteristics to be studied. Sn substitution fraction of 16 at% was discovered to maximize the crystallization temperature of GST thin films. Compared to the GST thin films, crystallization temperature difference and lower amorphous resistance of the GST:Sn thin films were mainly due to lower bonding energy of Sn–Te. Moreover, the amorphous conductivity activation energies (E σ) corresponding to different grain sizes were calculated with the Arrhenius equation. The E σ value of GST:Sn thin films decreased significantly as the Sn content increased due to grain size effects, which appears to improve the temperature stability of conductivity of phase change memory.

  15. Systematic study of GeSn heterostructure-based light-emitting diodes towards mid-infrared applications

    Science.gov (United States)

    Zhou, Yiyin; Dou, Wei; Du, Wei; Pham, Thach; Ghetmiri, Seyed Amir; Al-Kabi, Sattar; Mosleh, Aboozar; Alher, Murtadha; Margetis, Joe; Tolle, John; Sun, Greg; Soref, Richard; Li, Baohua; Mortazavi, Mansour; Naseem, Hameed; Yu, Shui-Qing

    2016-07-01

    Temperature-dependent characteristics of GeSn light-emitting diodes with Sn composition up to 9.2% have been systematically studied. Such diodes were based on Ge/GeSn/Ge double heterostructures (DHS) that were grown directly on a Si substrate via a chemical vapor deposition system. Both photoluminescence and electroluminescence spectra have been characterized at temperatures from 300 to 77 K. Based on our theoretical calculation, all GeSn alloys in this study are indirect bandgap materials. However, due to the small energy separation between direct and indirect bandgap, and the fact that radiative recombination rate greater than non-radiative, the emissions are mainly from the direct Γ-valley to valence band transitions. The electroluminescence emissions under current injection levels from 102 to 357 A/cm2 were investigated at 300 K. The monotonic increase of the integrated electroluminescence intensity was observed for each sample. Moreover, the electronic band structures of the DHS were discussed. Despite the indirect GeSn bandgap owing to the compressive strain, type-I band alignment was achieved with the barrier heights ranging from 11 to 47 meV.

  16. Azimuthal anisotropy of photon and charged particle emission in Pb-208+Pb-208 collisions at 158 center dot A GeV/c

    NARCIS (Netherlands)

    Aggarwal, MM; Ahammed, Z; Angelis, ALS; Antonenko, [No Value; Arefiev, [No Value; Astakhov, [No Value; Avdeitchikov, [No Value; Awes, TC; Baba, PVKS; Badyal, SK; Bathe, S; Batiounia, B; Bernier, T; Bhatia, VS; Blume, C; Bucher, D; Busching, H; Carlen, L; Chattopadhyay, S; Decowski, MP; Delagrange, H; Donni, P; Majumdar, MRD; Dubey, AK; El Chenawi, K; Enosawa, K; Fokin, S; Frolov, [No Value; Ganti, MS; Garpman, S; Gavrishchuk, O; Geurts, FJM; Ghosh, TK; Glasow, R; Gupta, R; Guskov, B; Gustafsson, H.A.; Gutbrod, HH; Hrivnacova, [No Value; Ippolitov, M; Kalechofsky, H; Kamermans, R; Karadjev, K; Karpio, K; Kolb, BW; Kosarev, [No Value; Koutcheryaev, [No Value; Kugler, A; Kulinich, P; Kurata, M; Lebedev, A; Löhner, H; Luquin, L; Mahapatra, DP; Manko, [No Value; Martin, M; Martinez, G; Maximov, A; Miake, Y; Mishra, GC; Mohanty, B; Mora, MJ; Morrison, D; Moukhanova, T; Mukhopadhyay, DS; Naef, H; Nandi, BK; Nayak, SK; Nayak, TK; Nianine, A; Nikitine, [No Value; Nikolaev, S; Nilsson, P; Nishimura, S; Nomokonov, P; Nystrand, J; Oskarsson, A; Otterlund, [No Value; Peitzmann, T; Peressounko, D; Phatak, SC; Pinganaud, W; Plasil, F; Purschke, ML; Rak, J; Raniwala, R; Raniwala, S; Rao, NK; Retiere, F; Reygers, K; Roland, G; Rosselet, L; Roufanov, [No Value; Roy, C; Rubio, JM; Sambyal, SS; Santo, R; Sato, S; Schlagheck, H; Schutz, Y; Shabratova, G; Shah, TH; Sharma, A; Sibiriak, [No Value; Siemiarczuk, T; Silvermyr, D; Sinha, BC; Slavine, N; Soderstrom, K; Sood, G; Sorensen, SP; Stankus, P; Stefanek, G; Steinberg, P; Stenlund, E; Sumbera, M; Svensson, T; Tsvetkov, A; Tykarski, L; van der Phjll, EC; van Eijndhoven, N; van Nieuwenhuizen, GJ; Vinogradov, A; Viyogi, YP; Vodopianov, A; Voros, S; Wyslouch, B; Young, GR

    The azimuthal distributions of photons and charged particles with respect to the event plane are investigated as a function of centrality in Pb-208 + Pb-208 collisions at 158 (.) A GeV/c in the WA98 experiment at the CERN SPS. The anisotropy of the azimuthal distributions is characterized using a

  17. Two-proton correlations from 158 A GeV Pb + Pb central collisions

    CERN Document Server

    Appelshauser, H.; Bailey, S.J.; Barna, D.; Barnby, L.S.; Bartke, J.; Barton, R.A.; Betev, L.; Bialkowska, H.; Billmeier, A.; Blyth, C.O.; Bock, R.; Boimska, B.; Bormann, C.; Brady, F.P.; Brockmann, R.; Brun, R.; Buncic, P.; Caines, H.L.; Carr, L.D.; Cebra, D.A.; Cooper, G.E.; Cramer, J.G.; Cristinziani, M.; Csato, P.; Dunn, J.; Eckardt, V.; Eckhardt, F.; Ferguson, M.I.; Fischer, H.G.; Flierl, D.; Fodor, Z.; Foka, P.; Freund, P.; Friese, V.; Fuchs, M.; Gabler, F.; Gal, J.; Ganz, R.; Gazdzicki, M.; Geist, Walter M.; Gladysz, E.; Grebieszkow, J.; Gunther, J.; Harris, J.W.; Hegyi, S.; Henkel, T.; Hill, L.A.; Hummler, H.; Igo, G.; Irmscher, D.; Jacobs, P.; Jones, P.G.; Kadija, K.; Kolesnikov, V.I.; Kowalski, M.; Lasiuk, B.; Lednicky, R.; Levai, P.; Malakhov, A.I.; Margetis, S.; Markert, C.; Melkumov, G.L.; Mock, A.; Molnar, J.; Nelson, John M.; Oldenburg, M.; Odyniec, G.; Palla, G.; Panagiotou, A.D.; Petridis, A.; Piper, A.; Porter, R.J.; Poskanzer, Arthur M.; Prindle, D.J.; Puhlhofer, F.; Susa, T.; Reid, J.G.; Renfordt, R.; Retyk, W.; Ritter, H.G.; Rohrich, D.; Roland, C.; Roland, G.; Rudolph, H.; Rybicki, A.; Sammer, T.; Sandoval, A.; Sann, H.; Semenov, A.Yu.; Schafer, E.; Schmischke, D.; Schmitz, N.; Schonfelder, S.; Seyboth, P.; Sikler, F.; Skrzypczak, E.; Snellings, R.; Squier, G.T.A.; Stock, R.; Strobele, H.; Struck, Chr.; Szentpetery, I.; Sziklai, J.; Toy, M.; Trainor, T.A.; Trentalange, S.; Ullrich, T.; Vassiliou, M.; Veres, G.; Vesztergombi, G.; Voloshin, S.; Vranic, D.; Wang, F.; Weerasundara, D.D.; Wenig, S.; Whitten, C.; Wood, L.; Xu, N.; Yates, T.A.; Zimanyi, J.; Zhu, X.Z.; Zybert, R.

    1999-01-01

    The two-proton correlation function at midrapidity from Pb+Pb central collisions at 158 AGeV has been measured by the NA49 experiment. The results are compared to model predictions from static thermal Gaussian proton source distributions and transport models RQMD and VENUS. An effective proton source size is determined by minimizing CHI-square/ndf between the correlation functions of the data and those calculated for the Gaussian sources, yielding 3.85 +- 0.15 (stat.) +- 0.15 (syst.) fm. The RQMD model overpredicts the effective source size, while the VENUS model underpredicts the effective source size.

  18. Growth and characterization of PbSe and Pb{sub 1{minus}x}Sn{sub x}Se layers on Si (100)

    Energy Technology Data Exchange (ETDEWEB)

    Sachar, H.K.; Chao, I.; Fang, X.M.; McCann, P.J. [Univ. of Oklahoma, Norman, OK (United States). School of Electrical and Computer Engineering

    1998-12-31

    Crack-free layers of PbSe were grown on Si (100) by a combination of liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) techniques. The PbSe layer was grown by LPE on Si(100) using a MBE-grown PbSe/BaF{sub 2}/CaF{sub 2} buffer layer structure. Pb{sub 1{minus}x}Sn{sub x}Se layers with tin contents in the liquid growth solution equal to 3%, 5%, 6%, 7%, and 10%, respectively, were also grown by LPE on Si(100) substrates using similar buffer layer structures. The LPE-grown PbSe and Pb{sub 1{minus}x}Sn{sub x}Se layers were characterized by optical Nomarski microscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Optical Nomarski characterization of the layers revealed their excellent surface morphologies and good growth solution wipe-offs. FTIR transmission experiments showed that the absorption edge of the Pb{sub 1{minus}x}Sn{sub x}Se layers shifted to lower energies with increasing tin contents. The PbSe epilayers were also lifted-off from the Si substrate by dissolving the MBE-grown BaF{sub 2} buffer layer. SEM micrographs of the cleaved edges revealed that the lifted-off layers formed structures suitable for laser fabrication.

  19. Strangeness production in p+Pb reactions at 200 GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Greiner, D.E. [Lawrence Berkeley Lab. (LBL), CA (United States); Andersen, E.; Blaes, R.; Cherney, M.; Cruz, B. de la; Fernandez, C.; Garabatos, C.; Garzon, J.A.; Geist, W.M.; Gruhn, C.R.; Hafidouni, M.; Hrubec, J.; Jones, P.G.; Judd, E.G.; Kuipers, J.P.M.; Ladrem, M.; Ladron de Guevara, P.; Loevhoeiden, G.; MacNaughton, J.; Mosquera, J.; Natkaniec, Z.; Nelson, J.M.; Neuhofer, G.; Perez de los Heros, C.; Plo, M.; Porth, P.; Powell, B.; Ramil, A.; Rohringer, H.; Sakrejda, I.; Thorsteinsen, T.F.; Traxler, J.; Voltolini, C.; Wozniak, K.; Yanez, A.; Zybert, R. [Fysisk Institutt, Bergen Univ. (Norway)]|[Centre de Recherches Nucleaires, IN2P3-CNRS/Univ. L. Pasteur, 67 -Strasbourg (France)]|[Creighton Univ., Dept. of Physics, Omaha, NE (United States)]|[CIEMAT, Div. de Fisica de Particulas, Madrid (Spain)]|[Universidad de Santiago de Compostela (Spain). Dept. de Fisica de Particulas]|[Lawrence Berkeley Lab. (LBL), CA (United States)]|[Inst. fuer Hochenergiephysik (HEPHY), Vienna (Austria)]|[Dept. of Physics, Birmingham Univ. (United Kingdom)]|[CERN, Geneva (Switzerland)]|[Instytut Fizyki Jadrowej, Krakow (Poland); NA36 Collaboration

    1994-01-03

    The production of the strange particles {Lambda}, anti {Lambda} and K{sub S}{sup 0} in p+Pb collisions at 200 GeV/c has been measured using the NA36 TPC. Rapidity distributions and multiplicity dependences are presented and compared to model calculations. Reinteractions in the target are important to describe the observed spectra. Inverse slopes T{approx}200 MeV are extracted from the transverse mass distributions. (orig.)

  20. Growth experiment of narrow band-gap semiconductor PbSnTe single crystals in space (M-1)

    Science.gov (United States)

    Yamada, Tomoaki

    1993-01-01

    An experiment on crystal growth of Pb(1-x)Sn(x)Te in microgravity is planned. This material is an alloy of the compound semiconductors PbTe and SnTe. It is a promising material for infrared diode lasers and detectors in the wavelength region between 6 and 30 micron. Since the electrical properties of Pb(1-x)Sn(x)Te depend greatly on the Pb/Sn ratio and crystalline defects as well as impurity concentration, homogeneous, defect-free, high-quality crystals are anticipated. Although many growth methods, such as the pulling method, the Bridgman method, the vapor growth method, etc., have been applied to the growth of Pb(1-x)Sn(x)Te, large, homogeneous, low-defect-density crystals have not yet been grown on Earth. The unsuccessful results were caused by buoyancy-driven convection in the fluids induced by the specific gravity difference between heated and cooled fluids on Earth. A crystal is grown by cooling the melt from one end of the ampoule. In crystal growth from the melt, about 30 percent of the SnTe in the melt is rejected at the solid-liquid interface during solidification. On Earth, the rejected SnTe is completely mixed with the remaining melt by convection in the melt. Therefore, SnTe concentration in the melt, and accordingly in the crystal, increases as the crystal grows. In the microgravity environment, buoyancy-driven convection is suppressed because the specific gravity difference is negligible. In that case, the rejected SnTe remains at the solid-liquid interface and its concentration increases only at the interface. If the growth rate is higher than the PbTe-SnTe interdiffusion rate, the amount of SnTe which diffuses from the interface into the melt increases as SnTe piles up at the interface, and finally it balances the amount of rejected SnTe during solidification, resulting in steady-state SnTe transportation at the interface. By using this principle, compositionally homogeneous crystals can be grown. Furthermore, low-defect-density crystals will be

  1. Recent progress in Ge and GeSn light emission on Si%Si基IV族异质结构发光器件的研究进展∗

    Institute of Scientific and Technical Information of China (English)

    何超; 张旭; 刘智; 成步文

    2015-01-01

    Si-based optical interconnection is expected to solve the problems caused by electric interconnection with increasing the density of integrated circuits, due to its merits of high speed, high bandwidth, and low consumption. So far, all of the key components except light source of Si-based optical interconnection have been demonstrated. Therefore, the light source has been considered as one of the most important components. Ge and GeSn based on Si have emerged as very promising candidates because of their high compatibility with Si CMOS processing, and the pseudo direct-bandgap characteristic. The energy difference between the direct and indirect bandgap of Ge is only 136 meV at room temperature. Under tensile strain or incorporation with Sn, the energy difference becomes smaller, and even less than zero, which means that Ge or GeSn changes into direct bandgap material. What is more, using large n-type doping to increase the fraction of electrons inΓ valley, we can further increase the luminous efficiency of Ge or GeSn. In this paper, we briefly overview the recent progress that has been reported in the study of Ge and GeSn light emitters for silicon photonics, including theoretical models for calculating the optical gain and loss, several common methods of introducing tensile strain into Ge, methods of increasing the n-type doping density, and the method of fabricating luminescent devices of Ge and GeSn. Finally, we discuss the challenges facing us and the development prospects, in order to have a further understanding of Ge and GeSn light sources. Several breakthroughs have been made in past years, especially in the realizing of lasing from GeSn by optically pumping and Ge by optically and electrically pumping, which makes it possible to fabricate a practical laser used in silicon photonics and CMOS technology.

  2. Si based mid-infrared GeSn photo detectors and light emitters

    Science.gov (United States)

    Du, Wei; Pham, Thach; Margetis, Joe; Tran, Huong; Ghetmiri, Seyed A.; Mosleh, Aboozar; Sun, Greg; Soref, Richard A.; Tolle, John; Naseem, Hameed A.; Li, Baohua; Yu, Shui-Qing

    2015-08-01

    In this work, high performance GeSn photoconductor and light emitting diodes (LED) have been demonstrated. For the photoconductor, the high responsivity was achieved due to high photoconductive gain, which is attributed to the novel optical and electrical design. The longwave cutoff at 2.4 μm was also observed at room temperature. For LED, temperature-dependent study was conducted. The electroluminescence (EL) spectra at different temperatures were obtained and EL peak shift was observed. Moreover, the emission power at different temperatures was measured. High power emission at 2.1 μm was achieved.

  3. Above-bandgap optical properties of biaxially strained GeSn alloys grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Richard D’Costa, Vijay, E-mail: elevrd@nus.edu.sg; Wang, Wei; Zhou, Qian; Yeo, Yee-Chia, E-mail: eleyeoyc@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore); Soon Tok, Eng [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

    2014-01-13

    The complex dielectric function of biaxially strained Ge{sub 1−x}Sn{sub x} (0 ≤ x ≤ 0.17) alloys grown on Ge (100) has been determined by spectroscopic ellipsometry from 1.2 to 4.7 eV. The effect of substitutional Sn incorporation and the epitaxial strain on the energy transitions E{sub 1}, E{sub 1} + Δ{sub 1}, E{sub 0}′, and E{sub 2} of GeSn alloys is investigated. Our results indicate that the strained GeSn alloys show Ge-like electronic bandstructure with all the transitions shifted downward due to the alloying of Sn. The strain dependence of E{sub 1} and E{sub 1} + Δ{sub 1} transitions is explained using the deformation potential theory, and values of −5.4 ± 0.4 eV and 3.8 ± 0.5 eV are obtained for the hydrostatic and shear deformation potentials, respectively.

  4. Local composition and carrier concentration in Pb0.7Ge0.3Te and Pb0.5Ge0.5Te alloys from 125Te NMR and microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Levin, E M [Ames Laboratory; Kramer, M J [Ames Laboratory; Schmidt-Rohr, K [Ames Laboratory

    2014-11-01

    Pb0.7Ge0.3Te and Pb0.5Ge0.5Te alloys, (i) quenched from 923 K or (ii) quenched and annealed at 573 K for 2 h, have been studied by 125Te NMR, X-ray diffraction, electron and optical microscopy, as well as energy dispersive spectroscopy. Depending on the composition and thermal treatment history, 125Te NMR spectra exhibit different resonance frequencies and spin-lattice relaxation times, which can be assigned to different phases in the alloy. Quenched and annealed Pb0.7Ge0.3Te alloys can be considered as solid solutions but are shown by NMR to have components with various carrier concentrations. Quenched and annealed Pb0.5Ge0.5Te alloys contain GeTe- and PbTe-based phases with different compositions and charge carrier concentrations. Based on the analysis of non-exponential 125Te NMR spin-lattice relaxation, the fractions and carrier concentrations of the various phases have been estimated. Our data show that alloying of PbTe with Ge results in the formation of chemically and electronically inhomogeneous systems. 125Te NMR can be used as an efficient probe to detect the local composition in equilibrium as well as non-equilibrium states, and to determine the local carrier concentrations in complex multiphase tellurides.

  5. Study of Various Processes with 160 A GeV Pb Beam

    CERN Multimedia

    2002-01-01

    % WA101 \\\\ \\\\ Ten modules of BP-1 glass detectors interleaved with various targets ranging from C to Pb were exposed to the 160~A~GeV~Pb beam in the November-December run of 1994 at CERN SPS. The experiment was carried out at normal incidence at a beam density of $\\sim$~600~cm$ ^- ^{2} $. The dimension of each plate of BP-1 glass was 50~mm~x~50~mm~x~1~mm. We etched the glass in 70\\% CH$ _{3} $SO$ _{3} $H at 50 $^{0}$C or in 48\\%~HF at room temperature. The charge threshold is found to be Z$ _{t} _{h} $ $\\sim$ 68 and 70 respectively. Using the automated scanning and measurement system developed at Berkeley, we have demonstrated that the charge resolution for Pb ions is $\\sigma _{Z} $~=~0.14 charge unit from a single measurement within a distance of 30~$\\mu$m. This excellent charge resolution allows us to make the proposed measurements of cross-sections for various processes. \\\\ \\\\We use this detector system to measure cross-sections for various processes in heavy ion collisions of 160~A~GeV~Pb with different t...

  6. Influence of IMC in the Semisolid Behaviour of an Eutectic Sn-Pb/Cu Slurry

    Science.gov (United States)

    Merizalde, Carlos; Cabrera, José-María; Prado, José-Manuel

    2007-04-01

    A mixture of a liquid Sn-Pb alloy reinforced with solid Cu particles has been found to show thixotropic and pseudoplastic behaviour. The presence of an intermetallic compound (IMC) between the Cu particles and the molten matrix has some very important consequences in the rheological behaviour of the slurry. The semisolid material is obtained mixing a sufficient amount of Cu particles with a liquid eutectic Sn-Pb alloy by mechanical stirring at a given temperature and time. The intermetallic compound is formed from the reaction of solid Cu and liquid Sn. This reaction results in some displacement in the phase diagram, affecting the liquid alloy composition, moving the liquidus temperature and therefore altering the balance of %wt solid- %wt liquid necessary to obtain the best thixotropic behaviour. In this work a model of the solid fraction of the slurry taking into account the IMC growth rate is presented. This model is also used to predict the processing window under which the material keeps the thixotropic behaviour.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-01

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

  8. Microscopic Study of the Isoscalar Giant Monopole Resonance in Cd, Sn and Pb Isotopes

    CERN Document Server

    Cao, Li-Gang; Colo, G

    2012-01-01

    The isoscalar giant monopole resonance (ISGMR) in Cd, Sn and Pb isotopes has been studied within the self-consistent Skyrme Hartree-Fock+BCS and quasi-particle random phase approximation (QRPA). Three Skyrme parameter sets are used in the calculations, i.e., SLy5, SkM* and SkP, since they are characterized by different values of the compression modulus in symmetric nuclear matter, namely K=230, 217, and 202 MeV, respectively. We also investigate the effect of different types of pairing forces on the ISGMR in Cd, Sn and Pb isotopes. The calculated peak energies and the strength distributions of ISGMR are compared with available experimental data. We find that SkP fails completely to describe the ISGMR strength distribution for all isotopes due to its low value of the nuclear matter incompressibility, namely K=202 MeV. On the other hand, the SLy5 parameter set, supplemented by an appropriate pairing interaction, gives a reasonable description of the ISGMR in Cd and Pb isotopes. A better description of ISGMR in ...

  9. Low temperature synthesis of lead germanate (PbGeO{sub 3})/polypyrrole (PPy) nanocomposites and their lithium storage performance

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jinkui, E-mail: jinkui@sdu.edu.cn [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials (Ministry of Education), School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Ci, Lijie; Qi, Yongxin; Lun, Ning [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials (Ministry of Education), School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Xiong, Shenglin; Qian, Yitai [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2014-09-15

    Highlights: • PbGeO{sub 3}/PPy nanocomposites are successfully fabricated for the first time. • PbGeO{sub 3} nanowire and PbGeO{sub 3}/PPy nanocomposites were characterized as anode materials in lithium ion batteries for the first time. • PPy coating can improve the electrochemical performance of PbGeO{sub 3} by increasing the electronic conductivity and buffering the volume changes during cycling. • The PbGeO{sub 3}/PPy nanocomposites deliver a capacity of 662 mA h g{sup −1} after 50 cycles. - Abstract: PGO/PPy nanocomposites were prepared via a low temperature chemical coating method for the first time. Electrochemical measurements demonstrate that the PbGeO{sub 3} electrodes retain a capacity of 657 mA h g{sup −1} after 100 cycles and possess excellent rate capability indicating that the PGO/PPy nanocomposites could be used as a candidate as high-capacity anode for lithium batteries.

  10. The Double Peaked SN2013ge: a Type Ib/c SN with an Early Asymmetric Mass Ejection or an Extended Progenitor Envelope

    CERN Document Server

    Drout, M R; Parrent, J; Margutti, R; Kamble, A; Soderberg, A M; Challis, P; Chornock, R; Fong, W; Frank, S; Gehrels, N; Graham, M L; Hsiao, E; Itagaki, K; Kasliwal, M; Kirshner, R P; Macomb, D; Marion, G H; Norris, J; Phillips, M M

    2015-01-01

    We present extensive observations of the Type Ib/c SN2013ge from -13 to +457 days, including spectra and Swift UV-optical photometry beginning 2-4 days post explosion. This makes SN2013ge one of the best observed normal Type Ib/c SN at early times, when the light curve is particularly sensitive to the progenitor configuration and mixing of radioactive elements. These early observations reveal two distinct light curve components in the UV bands. The first component rises over 4-5 days and is visible for a week post-explosion. Spectra of the first component have a blue continuum and show a plethora of high velocity (~14,000 km/s) but narrow (~3500 km/s) features, indicating that the line forming region is restricted. The explosion parameters estimated for the bulk explosion are standard for Type Ib/c SN, while detailed analysis of optical and NIR spectra identify weak He features at early times, and nebular spectra show evidence for mixing and asymmetry in the bulk ejecta. In addition, SN2013ge exploded in a lo...

  11. Low-temperature growth of Ge{sub 1} {sub -x}Sn{sub x} thin films with strain control by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Lin Hai, E-mail: hailin@stanford.edu [Department of Materials Science and Engineering, Stanford University, Stanford, California, 94305 (United States); Chen, Robert; Huo Yijie; Kamins, Theodore I.; Harris, James S. [Department of Electrical Engineering, Stanford University, Stanford, California, 94305 (United States)

    2012-03-30

    High-quality Ge{sub 1-x}Sn{sub x} thin films on InGaAs buffer layers have been demonstrated using low-temperature growth by molecular beam epitaxy. X-ray diffraction and secondary ion mass spectrometry are used to determine the strain and Sn concentration. Up to 10.5% Sn has been incorporated into the Ge{sub 1-x}Sn{sub x} thin film without Sn precipitation, as verified by transmission electron microscopy. Roughened surfaces are found for tensile strained Ge{sub 1-x}Sn{sub x} layers. - Highlights: Black-Right-Pointing-Pointer GeSn alloys were grown by molecular beam epitaxy with up to 10.5% Sn. Black-Right-Pointing-Pointer Unstrained GeSn alloys have high crystal quality. Black-Right-Pointing-Pointer Consistent Sn concentration was obtained from two different methods. Black-Right-Pointing-Pointer The growth of tensile strained GeSn results in a roughened surface.

  12. N-MOSFETs Formed on Solid Phase Epitaxially Grown GeSn Film with Passivation by Oxygen Plasma Featuring High Mobility.

    Science.gov (United States)

    Fang, Yung-Chin; Chen, Kuen-Yi; Hsieh, Ching-Heng; Su, Chang-Chia; Wu, Yung-Hsien

    2015-12-09

    Solid phase epitaxially grown GeSn was employed as the platform to assess the eligibility of direct O2 plasma treatment on GeSn surface for passivation of GeSn N-MOSFETs. It has been confirmed that O2 plasma treatment forms a GeSnO(x) film on the surface and the GeSnO(x) topped by in situ Al2O3 constitutes the gate stack of GeSn MOS devices. The capability of the surface passivation was evidenced by the low interface trap density (D(it)) of 1.62 × 10(11) cm(-2) eV(-1), which is primarily due to the formation of Ge-O and Sn-O bonds at the surface by high density/reactivity oxygen radicals that effectively suppress dangling bonds and decrease gap states. The good D(it) not only makes tiny frequency dispersion in the characterization of GeSn MOS capacitors, but results in GeSn N-MOSFETs with outstanding peak electron mobility as high as 518 cm(2)/(V s) which outperforms other devices reported in the literature due to reduced undesirable carrier scattering. In addition, the GeSn N-MOSFETs also exhibit promising characteristics in terms of acceptable subthreshold swing of 156 mV/dec and relatively large I(ON)/I(OFF) ratio more than 4 orders. Moreover, the robust reliability in terms small V(t) variation against high field stress attests the feasibility of using the O2 plasma-treated passivation to advanced GeSn technology.

  13. Mechanisms for Sn whisker growth in rare earth-containing Pb-free solders

    Energy Technology Data Exchange (ETDEWEB)

    Dudek, M.A. [School of Materials, Fulton School of Engineering, Arizona State University, Tempe, AZ 85287-8706 (United States); Chawla, N., E-mail: Nikhilesh.Chawla@asu.edu [School of Materials, Fulton School of Engineering, Arizona State University, Tempe, AZ 85287-8706 (United States)

    2009-09-15

    It has recently been documented that Pb-free solder alloys doped with trace amounts of rare earth (RE) elements show a very strong propensity to grow Sn whiskers. In this work, we have investigated the effect of the addition of 2 wt.% Ce, La or Y on the whiskering behavior of Sn-3.9Ag-0.7Cu. Hillock-type whiskers around particle peripheries were observed in water-quenched alloys with smaller RESn{sub 3} particles, while furnace-cooled alloys with larger RESn{sub 3} particles formed needle-like whiskers from within the particle. Phase separation between Sn and RE oxides occurred during oxidation of the RESn{sub 3} intermetallics. A focused ion beam serial sectioning approach was used to visualize the Sn whiskers and the oxide structure. We show that the driving force for whisker growth is related to the compressive stresses that develop in these particles during the oxidation of the RE intermetallic phases.

  14. Whisker-Like Formations in Sn-3.0Ag-Pb Alloys

    Directory of Open Access Journals (Sweden)

    Koncz-Horváth D.

    2017-06-01

    Full Text Available In this study, different types of whisker-like formations of Sn-3.0Ag based alloy were presented. In the experimental process the amount of Pb element was changed between 1000 and 2000 ppm, and the furnace atmosphere and cooling rate were also modified. The novelty of this work was that whisker-like formations in macro scale size were experienced after an exothermic reaction. The whiskers of larger sizes than general provided opportunities to investigate the microstructure and the concentration nearby the whiskers. In addition, the whisker-like formations from Sn-Ag based bulk material did not only consist of pure tin but tin and silver phases. The whisker-like growth appeared in several forms including hillock, spire and nodule shaped formations in accordance with parameters. It was observed that the compound phases were clustered in many cases mainly at hillocks.

  15. Molecular epitaxy of pseudomorphic Ge1-y Sn y (y = 0.06-0.17) structures and devices on Si/Ge at ultra-low temperatures via reactions of Ge4H10 and SnD4

    Science.gov (United States)

    Wallace, P. M.; Senaratne, C. L.; Xu, Chi; Sims, P. E.; Kouvetakis, J.; Menéndez, J.

    2017-02-01

    A low-pressure CVD technique was specifically developed to prepare a new class of pseudomorphic Ge1-y Sn y layers, with an Sn content up to 17% on Ge-buffered Si(100) wafers. The growth is conducted via reactions of SnD4 and the recently deployed Ge4H10 custom precursor, whose large molecular weight and enhanced reactivity enables depositions at unprecedented ultra-low temperatures (150 °C-200 °C), and at pressures akin to those typically employed in solid/gas-source MBE. The thicknesses of the layers far exceed the critical limits predicted by thermodynamic considerations and are either comparable to, or larger than, those observed for MBE-grown samples. This is validated by modeling of the thickness versus the composition for the fully strained and partially relaxed alloys produced in this work relative to the MBE and CVD-grown analogs reported in the literature. Furthermore, the practical relevance of the technique was demonstrated by creating highly doped n-type alloys, which were then used as active layers to fabricate degenerate pn junctions. It was also found that the strained films gradually relax with increasing thickness, providing new types of strain-free material with enhanced optical quality relative to those produced by standard CVD methods, as evidenced by the photoluminescence studies. The strain relaxation mechanism appears to be similar to that observed in CVD-grown samples, with no sign of epitaxial breakdown or precipitous degradation of the bulk crystallinity or surface morphology, in spite of the low growth temperatures employed. Finally, we note that this method represents the first example of a chemically driven route that delivers materials with the desirable properties afforded by MBE, while offering the potential for those practical applications inherent to large-scale CVD.

  16. Ferroelectric Properties of Pt/Pb5Ge3O11/Pt and Pt/Pb5Ge3O11/HfO2/Si Structures

    Science.gov (United States)

    Ohara, Shuichiro; Aizawa, Koji; Ishiwara, Hiroshi

    2005-09-01

    The ferroelectric properties of metal-ferroelectric-metal (MFM) capacitors with a Pt/Pb5Ge3O11(PGO)/Pt structure and metal-ferroelectric-insulator-semiconductor (MFIS) diodes with a Pt/PGO/HfO2/Si structure were investigated. C-axis-oriented PGO thin films were formed on both Pt/SiO2/Si and HfO2 (6 nm)/Si structures by a sol-gel method. Typical values of remanent polarization (2Pr), coercive field (2Ec), and dielectric constant in the MFM capacitors were 5.7 μC/cm2, 63 kV/cm, and 50, respectively, and the remanent polarization gradually increased with the switching pulses for up to 1 × 1010 cycles. It was also found that the memory window in the MFIS diodes with a 340-nm-thick PGO film was as large as 1.3 V.

  17. Comparison of the Molecular Interaction Volume Model with the Wagner Formulae in the Zn-Pb-In and Zn-Sn-Cd-Pb Dilute Solutions

    Institute of Scientific and Technical Information of China (English)

    Dongping TAO; Zhuo CHEN; Dunfang LI; Yifeng GAO; Qianghua SHEN

    2004-01-01

    The coordination numbers in the molecular interaction volume model (MIVM) can be calculated from the common physical quantities of pure liquid metals. A notable feature of the model lie in its capability to predict the thermodynamic properties of solutes in the Zn-Pb-ln and Zn-Sn-Cd-Pb dilute solutions using only the binary infinite dilute activity coefficients, and the predicted values are in good agreement with the experimental data of the dilute solutions.

  18. Theoretical - Experimental Analysis of Cellular and Primary Dendritic Spacings during Unidirectional Solidification of Sn-Pb Alloys

    Directory of Open Access Journals (Sweden)

    Otávio F.L. da Rocha

    2002-09-01

    Full Text Available Structural parameters as grain size, dendritic and cellular spacings, segregated products, porosity and other phases are strongly influenced by the thermal behavior of the metal/mold system during solidification, imposing a close correlation between this and the resulting microstructure. Several unidirectional solidification studies with the objective of characterizing cellular and dendritic spacings have been developed in large scale involving solidification in steady-state heat flow. The main objective of this work is to determine the thermal solidification parameters during the cellular/dendritic transition as well as to compare theoretical models that predict cellular and primary dendritic spacings with experimental results for solidification situations in unsteady-state heat flow. Experiments were carried out in a water cooled unidirectional solidification apparatus and dilute alloys of the Sn-Pb system were used (Sn 1.5wt%Pb, Sn 2.5wt%Pb and Sn 5wt%Pb. The upper limit of the Hunt-Lu cellular growth model closely matched the experimental spacings. The lower limit calculated with the Hunt-Lu dendritic model best generated the experimental results. The cellular/dendritic transition was observed to occur for the Sn 2.5wt%Pb alloy over a range of analytical cooling rates from 0.28 K/s to 1.8 K/s.

  19. Release of charges under external fields of PbLa(Zr,Sn,Ti)O3 ceramic

    Institute of Scientific and Technical Information of China (English)

    Zhang Chong-Hui; Xu Zhuo; Gao Jun-Jie; Yao Xi

    2011-01-01

    This paper investigates the pyroelectric of poled antiferroelectric (AFE) ceramic Pb0.97La0.02 (Zr0.69Sn0.196 Ti0.114)O3 and its remnant polarization dependence of hydrostatic pressure. The results show that the bound charges of poled sample can be released in short time by temperature field or pressure field. The released charge abruptly forms a large pulse current. The phenomena of released charge under external fields result in the ferroelectric-AFE phase transition induced by temperature or hydrostatic pressure.

  20. Pyroelectric spectrum in Pb(Zr,Sn,Ti)O3 antiferroelectric- ferroelectric ceramics

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The pyroelectric effect of phase transition induced with temperature in Nb-modified Pb(Zr,Sn,Ti)O3 antiferroelectric-ferroelectric ceramics is studied. Experimental results reveal that the phase transitions are accompanied with marked pyroelectric peaks, there exists the close relation between the type of phase transition and the shape of pyroelectric peak. Because of the variations of phase transition, various pyroelectric spectra result. The pyroelectric spectrum can display the polarization effect and some inferior phase transitions with temperature variations, such as antiferroelectric AFEA-AFEB or ferroelectric FEL-FEH transition, which are not detected by the conventional dielectric measurement.

  1. Excitation of Giant Monopole Resonance in $^{208}$Pb and $^{116}$Sn Using Inelastic Deuteron Scattering

    CERN Document Server

    Patel, D; Itoh, M; Akimune, H; Berg, G P A; Fujiwara, M; Harakeh, M N; Iwamoto, C; Kawabata, T; Kawase, K; Matta, J T; Murakami, T; Okamoto, A; Sako, T; Schlax, K W; Takahashi, K; White, M; Yosoi, M

    2014-01-01

    The excitation of the isoscalar giant monopole resonance (ISGMR) in $^{116}$Sn and $^{208}$Pb has been investigated using small-angle (including $0^\\circ$) inelastic scattering of 100 MeV/u deuteron and multipole-decomposition analysis (MDA). The extracted strength distributions agree well with those from inelastic scattering of 100 MeV/u $\\alpha$ particles. These measurements establish deuteron inelastic scattering at E$_d \\sim$ 100 MeV/u as a suitable probe for extraction of the ISGMR strength with MDA, making feasible the investigation of this resonance in radioactive isotopes in inverse kinematics.

  2. I-V measurements of Ge-Se-Sn chalcogenide glassy alloys

    Directory of Open Access Journals (Sweden)

    Vandana Kumari

    2015-03-01

    Full Text Available Current-voltage characteristics and DC electrical conductivity were studied for Ge30-xSe70Snx (x = 8, 11, 14, 17 and 20 glassy thin pellets of diameter 12 mm and thickness 1 mm prepared under a constant load of 5 tons using a well-known melt quenching technique in bulk as a function of composition. The I-V characteristics were recorded at room temperature as well as elevated temperatures up to 300 °C. The experimental data suggests that glass containing 20 at.% of Sn has the minimum resistance allowing maximum current through the sample as compared to other counterparts of the series. Therefore, DC conductivity is found to increase with increasing Sn concentration. Composition dependence of DC conductivity is discussed in terms of the bonding between Se and Sn. Plots between ln I and V1/2 provide linear relationship for both low and high voltage range. These results have been explained through the Pool-Frenkel mechanism. The I-V characteristics show ohmic behaviour in the low voltage range and this behaviour turns to non-ohmic from ohmic in the higher voltage range due to voltage induced temperature effects.

  3. An optically pumped 2.5 μm GeSn laser on Si operating at 110 K

    Science.gov (United States)

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

    2016-10-01

    This paper reports the demonstration of optically pumped GeSn edge-emitting lasers grown on Si substrates. The whole device structures were grown by an industry standard chemical vapor deposition reactor using the low cost commercially available precursors SnCl4 and GeH4 in a single run epitaxy process. Temperature-dependent characteristics of laser-output versus pumping-laser-input showed lasing operation up to 110 K. The 10 K lasing threshold and wavelength were measured as 68 kW/cm2 and 2476 nm, respectively. Lasing characteristic temperature (T0) was extracted as 65 K.

  4. High-Frequency (1)H NMR Chemical Shifts of Sn(II) and Pb(II) Hydrides Induced by Relativistic Effects: Quest for Pb(II) Hydrides.

    Science.gov (United States)

    Vícha, Jan; Marek, Radek; Straka, Michal

    2016-10-17

    The role of relativistic effects on (1)H NMR chemical shifts of Sn(II) and Pb(II) hydrides is investigated by using fully relativistic DFT calculations. The stability of possible Pb(II) hydride isomers is studied together with their (1)H NMR chemical shifts, which are predicted in the high-frequency region, up to 90 ppm. These (1)H signals are dictated by sizable relativistic contributions due to spin-orbit coupling at the heavy atom and can be as large as 80 ppm for a hydrogen atom bound to Pb(II). Such high-frequency (1)H NMR chemical shifts of Pb(II) hydride resonances cannot be detected in the (1)H NMR spectra with standard experimental setup. Extended (1)H NMR spectral ranges are thus suggested for studies of Pb(II) compounds. Modulation of spin-orbit relativistic contribution to (1)H NMR chemical shift is found to be important also in the experimentally known Sn(II) hydrides. Because the (1)H NMR chemical shifts were found to be rather sensitive to the changes in the coordination sphere of the central metal in both Sn(II) and Pb(II) hydrides, their application for structural investigation is suggested.

  5. Adsorption study of Pb2+ ions on nanosized SnO2, synthesized by self-propagating combustion reaction

    Indian Academy of Sciences (India)

    Arunkumar Lagashetty; A Venkataraman

    2004-12-01

    Novel combustion synthetic route for the synthesis of nanosized SnO2 is reported. X-ray, tap and powder densities of SnO2 are calculated. Adsorption of Pb2+ ions on combustion derived nanosized SnO2 is studied. The as synthesized SnO2 and lead ions adsorbed SnO2 are characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), and infrared spectroscopic (IR) techniques. The eluent is characterized by atomic absorption spectroscopy (AAS) and solution conductivity (SC) to know the reduction in the concentration and increase in conductance of lead solution after adsorption on the SnO2 surface. The potential use of solid adsorbents for the adsorption of heavy metal pollutants is envisaged in the present work.

  6. Isothermal section of the Ag{sub 2}S-PbS-GeS{sub 2} system at 300 K and the crystal structure of Ag{sub 2}PbGeS{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Kogut, Yu. [Department of Inorganic and Physical Chemistry, Volyn State University, 13 Voli Avenue, 43025 Lutsk (Ukraine); Fedorchuk, A. [Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, 50 Pekarska St., 79010 Lviv (Ukraine); Zhbankov, O. [Department of Inorganic and Physical Chemistry, Volyn State University, 13 Voli Avenue, 43025 Lutsk (Ukraine); Romanyuk, Ya. [EMPA, Swiss Federal Laboratories for Materials Testing and Research, 8600 Dubendorf (Switzerland); Kityk, I. [Electrical Engineering Department, Czestochowa University of Technology, Al. Armii Krajowej 17/19, 42-200 Czestochowa (Poland); Piskach, L. [Department of Inorganic and Physical Chemistry, Volyn State University, 13 Voli Avenue, 43025 Lutsk (Ukraine); Parasyuk, O., E-mail: oleg@univer.lutsk.ua [Department of Inorganic and Physical Chemistry, Volyn State University, 13 Voli Avenue, 43025 Lutsk (Ukraine)

    2011-03-17

    Research highlights: > The isothermal section of the quasi-ternary system Ag{sub 2}S-PbS-GeS{sub 2} was investigated by X-ray powder diffraction. The phase equilibria between the binary system components and the ternary and the quaternary compounds were identified. > The crystal structure of the quaternary compound Ag{sub 2}PbGeS{sub 4} was investigated by single crystal X-ray diffraction. The compound crystallizes in an own structural type in a non-centrosymmetric space group Ama2 with the lattice parameters a = 1.02390(4) nm, b = 1.02587(5) nm, c = 0.67701(3) nm. - Abstract: The isothermal section of the Ag{sub 2}S-PbS-GeS{sub 2} system at room temperature was investigated by XRD. The existence of two quaternary compounds, Ag{sub 2}PbGeS{sub 4} and Ag{sub 0.5}Pb{sub 1.75}GeS{sub 4}, was confirmed, and the phase equilibria between the binary system components and the ternary and the quaternary compounds were determined. The crystal structure of Ag{sub 2}PbGeS{sub 4} was studied using the single crystal X-ray diffraction. It was established that Ag{sub 2}PbGeS{sub 4} crystallizes in an own structural type in non-centrosymmetric space group Ama2 with the lattice parameters a = 1.02390(4) nm, b = 1.02587(5) nm, c = 0.67701(3) nm.

  7. Simulation investigation of tensile strained GeSn fin photodetector with Si(3)N(4) liner stressor for extension of absorption wavelength.

    Science.gov (United States)

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

    2015-01-26

    In this paper, we design a biaxial tensile strained GeSn photodetector with fin structure wrapped in Si(3)N(4) liner stressor. A large biaxial tensile strain is induced in GeSn fins by the expansion of Si(3)N(4) liner stressor. The distribution of tensile strain in GeSn fins was calculated by a finite element simulation. It is observed that magnitude of the strain increases with the reduction of fin thickness T(fin). Under the biaxial tensile strain, the direct band gap E(G,Γ) of GeSn fin photodetector is significantly reduced by lowering Γ conduction valley in energy and lifting of degeneracy of valence bands. As the 30 nm Si(3)N(4) liner stressor expanses by 1%, a E(G,Γ) reduction of ~0.14 eV is achieved in Ge(0.92)Sn(0.08) fins with a T(fin) of 100 nm. The cut-off wavelengths of strained Ge(0.96)Sn(0.04), Ge(0.92)Sn(0.08) and Ge(0.90)Sn(0.10) fin photodetectors with a T(fin) of 100 nm are extended to 2.4, 3.3, and 4 μm, respectively. GeSn fin photodetector integrated with Si(3)N(4) liner stressor provides an effective technique for extending the absorption edge of GeSn with Sn composition less than 10% to mid-infrared wavelength.

  8. Ge0.83Sn0.17 p-channel metal-oxide-semiconductor field-effect transistors: Impact of sulfur passivation on gate stack quality

    Science.gov (United States)

    Lei, Dian; Wang, Wei; Zhang, Zheng; Pan, Jisheng; Gong, Xiao; Liang, Gengchiau; Tok, Eng-Soon; Yeo, Yee-Chia

    2016-01-01

    The effect of room temperature sulfur passivation of the surface of Ge0.83Sn0.17 prior to high-k dielectric (HfO2) deposition is investigated. X-ray photoelectron spectroscopy (XPS) was used to examine the chemical bonding at the interface of HfO2 and Ge0.83Sn0.17. Sulfur passivation is found to be effective in suppressing the formation of both Ge oxides and Sn oxides. A comparison of XPS results for sulfur-passivated and non-passivated Ge0.83Sn0.17 samples shows that sulfur passivation of the GeSn surface could also suppress the surface segregation of Sn atoms. In addition, sulfur passivation reduces the interface trap density Dit at the high-k dielectric/Ge0.83Sn0.17 interface from the valence band edge to the midgap of Ge0.83Sn0.17, as compared with a non-passivated control. The impact of the improved Dit is demonstrated in Ge0.83Sn0.17 p-channel metal-oxide-semiconductor field-effect transistors (p-MOSFETs). Ge0.83Sn0.17 p-MOSFETs with sulfur passivation show improved subthreshold swing S, intrinsic transconductance Gm,int, and effective hole mobility μeff as compared with the non-passivated control. At a high inversion carrier density Ninv of 1 × 1013 cm-2, sulfur passivation increases μeff by 25% in Ge0.83Sn0.17 p-MOSFETs.

  9. Diaminogermylene and diaminostannylene derivatives of gold(I): novel AuM and AuM2 (M = Ge, Sn) complexes.

    Science.gov (United States)

    Cabeza, Javier A; Fernández-Colinas, José M; García-Álvarez, Pablo; Polo, Diego

    2012-03-19

    The reactions of [AuCl(THT)] (THT = tetrahydrothiophene) with 1 equiv of the group 14 diaminometalenes M(HMDS)(2) [M = Ge, Sn; HMDS = N(SiMe(3))(2)] lead to [Au{MCl(HMDS)(2)}(THT)] [M = Ge (1), Sn (2)], which contain a metalate(II) ligand that arises from insertion of the corresponding M(HMDS)(2) reagent into the Au-Cl bond of the gold(I) reagent. While compound 1 reacts with more Ge(HMDS)(2) to give the germanate-germylene derivative [Au{GeCl(HMDS)(2)}{Ge(HMDS)(2)}] (3), which results from substitution of Ge(HMDS)(2) for the THT ligand of 1, an analogous treatment of compound 2 with Sn(HMDS)(2) gives the stannate-stannylene derivative [Au{SnCl(HMDS)(2)}{Sn(HMDS)(2)(THT)}] (4), which has a THT ligand attached to the stannylene tin atom and which, in solution at room temperature, participates in a dynamic process that makes its two Sn(HMDS)(2) fragments equivalent (on the NMR time scale). A similar dynamic process has not been observed for the AuGe(2) compound 3 or for the AuSn(2) derivatives [Au{SnR(HMDS)(2)}{Sn(HMDS)(2)(THT)}] [R = Bu (5), HMDS (6)], which have been prepared by treating complex 4 with LiR. The structures of compounds 1 and 3-6 have been determined by X-ray diffraction.

  10. Enhanced Thermoelectric Properties of Sn0.8Pb0.2Te Alloy by Mn Substitution

    Science.gov (United States)

    Li, J. Q.; Lu, Z. W.; Wang, C. Y.; Li, Y.; Liu, F. S.; Ao, W. Q.

    2016-06-01

    A series of (Sn0.8Pb0.2)1- x Mn x Te alloys with x = 0, 0.03, 0.06, 0.09, 0.12 and 0.15 were prepared by melting, quenching and spark plasma sintering (SPS) techniques to investigate their phases and thermoelectric properties. Mn was used as doped element in Sn0.8Pb0.2Te solid solution to reduce the carrier concentration, enhance the Seebeck coefficient and reduce the thermal conductivity of the material. Experimental results show that the SnTe-based solid solution single phase was formed in the alloys with x = 0 and 0.03. The minor irregular-shaped MnTe2 phase presents in the alloys with x ≥ 0.06, while the minor needle-like MnTe phase appears in the alloys with x ≥ 0.12, together with the SnTe-based solid solution matrix. The lattice parameter a of SnTe-based solid solution decreases nearly linearly as Mn content x increases up to 0.12, but keeps constant as x further increases. All the samples show p-type conduction. Mn doping in Sn0.8Pb0.2Te decreases its carrier concentration and thus increases its Seebeck coefficient. The solute Mn and Pb atoms in the SnTe-based solid solution, and the minor phases MnTe2 and MnTe, enhance the phonon scattering and thus reduce the thermal conductivity. As a result, the figure-of-merit ZT of the (Sn0.8Pb0.2)1- x Mn x Te composites can be enhanced with proper Mn substitution. The maximum ZT of 0.65 was obtained in the sample (Sn0.8Pb0.2)0.88Mn0.12Te at 723 K, which is higher than the 0.29 of its parent alloy Sn0.8Pb0.2Te.

  11. Formation of nanocrystalline GeSn thin film on Si substrate by sputtering and rapid thermal annealing

    Science.gov (United States)

    Mahmodi, H.; Hashim, M. R.; Hashim, U.

    2016-10-01

    Nanocrystalline Ge1-xSnx thin films have been formed after rapid thermal annealing of sputtered GeSn layers. The alloy films were deposited onto the Silicon (100) substrate via low cost radio frequency magnetron sputtering. Then, the films were annealed by rapid thermal annealing at 350 °C, 400 °C, and 450 °C for 10 s. The morphological, structural, and optical properties of the layers were investigated with field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and high-resolution X-ray diffraction (HR-XRD). The Raman analysis showed that the only observed phonon mode is attributed to Ge-Ge vibrations. Raman phonon intensities of GeSn thin films were enhanced with increasing the annealing temperature. The results clearly revealed that by increasing the annealing temperature the crystalline quality of the films were improved. The XRD measurements revealed the nanocrystalline phase formation in the annealed films with (111) preferred orientation. The results showed the potentiality of using the sputtering technique and rapid thermal anneal to produce crystalline GeSn layer.

  12. Temperature dependence of the Moessbauer effect on the semiconductors Pb{sub 0.78}Sn{sub 0.22}Te and Pb{sub 0.80}Sn{sub 0.20}Te:In

    Energy Technology Data Exchange (ETDEWEB)

    Ragimova, T. [Universidad de Antioquia, A.A, Departamento de Fisica (Colombia); Pacheco Serrano, W.A. [Universidad Pedagogica y Tecnologica, A.A. 1094, Departamento de Fisica (Colombia); Abras, A. [Universidade Federal de Minas Gerais, Departamento de Fisica, ICEx (Brazil)

    1999-11-15

    Crystals of the semiconductors Pb{sub 0.78}Sn{sub 0.22}Te and Pb{sub 0.80}Sn{sub 0.20}Te:In were grown by Bridgman method, and investigated by Moessbauer spectroscopy and X-ray diffraction. Moessbauer spectra were taken at temperatures between 80 and 300 K. The absence of the quadrupole splitting shows a cubic symmetry of the environment for the tin atom, which is in accordance with X-ray data. The temperature dependence of the spectral area is discussed and the Debye temperature is estimated.

  13. Enhancement of photoluminescence from n-type tensile-strained GeSn wires on an insulator fabricated by lateral liquid-phase epitaxy

    Science.gov (United States)

    Shimura, Takayoshi; Matsue, Masahiro; Tominaga, Kohei; Kajimura, Keiko; Amamoto, Takashi; Hosoi, Takuji; Watanabe, Heiji

    2015-11-01

    We investigated the optical properties of undoped and n-type GeSn wires fabricated by a lateral liquid-phase epitaxial method. The Sn concentration was approximately 0.5% in the region from the seed to near the wire end. Moreover, the Sn concentration increased to 6% at the wire end, whereas Si diffusion from the seed was enhanced and extended to 200 μm from the seed. Tensile strain gradually decreased from 0.5% close the seed to 0.25% at the wire end. The photoluminescence (PL) peak was red-shifted by Sn incorporation into the Ge wires, and a PL peak at 0.66 eV was observed from the wire end. Upon n-type doping, the PL intensity of the GeSn layers was significantly enhanced to approximately 10 times higher than that of the undoped GeSn wires.

  14. Atomic layer deposition of Al{sub 2}O{sub 3} on germanium-tin (GeSn) and impact of wet chemical surface pre-treatment

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Suyog, E-mail: suyog@stanford.edu; Chen, Robert; Harris, James S.; Saraswat, Krishna C. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

    2013-12-09

    GeSn is quickly emerging as a potential candidate for high performance Si-compatible transistor technology. Fabrication of high-ĸ gate stacks on GeSn with good interface properties is essential for realizing high performance field effect transistors based on this material system. We demonstrate an effective surface passivation scheme for n-Ge{sub 0.97}Sn{sub 0.03} alloy using atomic layer deposition (ALD) of Al{sub 2}O{sub 3}. The effect of pre-ALD wet chemical surface treatment is analyzed and shown to be critical in obtaining a good quality interface between GeSn and Al{sub 2}O{sub 3}. Using proper surface pre-treatment, mid-gap trap density for the Al{sub 2}O{sub 3}/GeSn interface of the order of 10{sup 12} cm{sup −2} has been achieved.

  15. One-, Two- and Three-Particle Distributions from 158 A GeV/c Central Pb+Pb Collisions

    CERN Document Server

    Aggarwal, M M; Antonenko, V G; Arefev, V; Astakhov, V A; Avdeichikov, V; Awes, T C; Baba, P V K S; Badyal, S K; Bathe, S; Batyunya, B; Bernier, T; Bhalla, K B; Bhatia, V S; Blume, C; Bucher, D; Büsching, H; Carlén, L; Chattopadhyay, S; Decowski, M P; Delagrange, H; Dönni, P; Dutta-Majumdar, M R; El-Chenawi, K F; Enosawa, K; Fokin, S; Frolov, V; Ganti, M S; Garpman, S; Gavrishchuk, O P; Geurts, F J M; Ghosh, T K; Glasow, R; Guskov, B; Gustafsson, Hans Åke; Gutbrod, H H; Hrivnacova, I; Ippolitov, M S; Kalechofsky, H; Kamermans, R; Karadzhev, K; Karpio, K; Kolb, B W; Kosarev, I; Kucheryaev, I; Kugler, A; Kulinich, P; Kurata, M; Lebedev, A; Löhner, H; Mahapatra, D P; Man'ko, V; Martin, M; Martínez, G; Maksimov, A; Miake, Y; Mishra, G C; Mohanty, B; Mora, M J; Morrison, D; Mukhanova, T; Mukhopadhyay, D S; Naef, H; Nandi, B K; Nayak, S K; Nayak, T K; Nyanin, A; Nikitin, V; Nikolaev, S; Nilsson, P; Nishimura, S; Nomokonov, V P; Nystrand, J; Oskarsson, A; Otterlund, I; Peitzmann, T; Peressounko, D Yu; Petracek, V; Plasil, F; Purschke, M L; Rak, J; Raniwala, R; Raniwala, S; Rao, N K; Reygers, K; Roland, G; Rosselet, L; Rufanov, I; Rubio, J M; Sambyal, S S; Santo, R; Sato, S; Schlagheck, H; Schmidt, H R; Schutz, Y; Shabratova, G; Shah, T H; Sibiryak, Yu; Siemiarczuk, T; Silvermyr, D; Sinha, B C; Slavin, N V; Söderström, K; Sood, G; Sørensen, S P; Stankus, P; Stefanek, G; Steinberg, P; Stenlund, E; Sumbera, M; Svensson, T; Tsvetkov, A; Tykarski, L; Van den Pijll, E C; van Eijndhoven, N; van Nieuwenhuizen, G J; Vinogradov, A; Viyogi, Y P; Vodopyanov, A S; Vörös, S; Wyslouch, B; Young, G R

    2003-01-01

    Several hadronic observables have been studied in central 158 A GeV Pb+Pb collisions using data measured by the WA98 experiment at CERN: single negative pion and kaon production, as well as two- and three-pion interferometry. The Wiedemann-Heinz hydrodynamical model has been fitted to the pion spectrum, giving an estimate of the temperature and transverse flow velocity. Bose-Einstein correlations between two identified negative pions have been analysed as a function of kT, using two different parameterizations. The results indicate that the source does not have a strictly boost invariant expansion or spend time in a long-lived intermediate phase. A comparison between data and a hydrodynamical based simulation shows very good agreement for the radii parameters as a function of kT. The pion phase-space density at freeze-out has been measured and agrees well with the Tomasik-Heinz model. A large pion chemical potential close to the condensation limit of the pion mass seems to be excluded. The three-pion Bose-Ein...

  16. $\\phi$ production in Pb-Pb collisions at 158 GeV/c per nucleon incident momentum

    CERN Document Server

    Alessandro, B; Arnaldi, R; Astruc, J; Atayan, M; Baglin, C; Baldit, A; Beolè, S; Boldea, V; Bordalo, P; Borges, G; Bussière, A; Capelli, L; Caponi, V; Castanier, C; Castor, J I; Chaurand, B; Chevrot, I; Cheynis, B; Chiavassa, E; Cicalò, C; Claudino, T; Comets, M P; Constans, N; Constantinescu, S; Cortese, P; Cruz, J; De Falco, A; De Marco, N; Dellacasa, G; Devaux, A; Dita, S; Drapier, O; Ducroux, L; Espagnon, B; Fargeix, J; Force, P; Gallio, M; Gavrilov, Yu K; Gerschel, C; Giubellino, P; Golubeva, M B; Gonin, M; Grigorian, A A; Grigoryanm, S; Grossiord, J Y; Guber, F F; Guichard, A; Gulkanian, H R; Hakobyan, R S; Idzik, M; Jouan, D; Karavitcheva, T L; Kluberg, L; Kurepin, A B; Le Bornec, Y; Lourenço, C; Macciotta, P; MacCormick, M; Marzari-Chiesa, A; Masera, M; Masoni, A; Monteno, M; Musso, A; Petiau, P; Piccotti, A; Pizzi, J R; Da Silva, W; Prino, F; Puddu, G; Quintans, C; Ramello, L; Ramos, S; Rato-Mendes, P; Riccati, L; Romana, A; Santos, H; Saturnini, P; Scalas, E; Scomparin, E; Serci, S; Shahoyan, R; Sigaudo, F; Silva, S; Sitta, M; Sonderegger, P; Tarrago, X; Topilskaya, N S; Usai, G L; Vercellin, Ermanno; Villatte, L; Willis, N

    2003-01-01

    The production of vector mesons phi , rho and omega has been measured in Pb-Pb collisions at 158 GeV/c per nucleon incident momentum at the CERN/SPS. The muon spectrometer of experiment NA50 detects phi , rho and omega mesons via their mu /sup +/ mu /sup -/ decay channel in the collision center of mass rapidity range 0

  17. Alkaline earth lead and tin compounds Ae2Pb, Ae2Sn, Ae = Ca, Sr, Ba, as thermoelectric materials

    Directory of Open Access Journals (Sweden)

    David Parker and David J Singh

    2013-01-01

    Full Text Available We present a detailed theoretical study of three alkaline earth compounds Ca2Pb, Sr2Pb and Ba2Pb, which have undergone little previous study, calculating electronic band structures and Boltzmann transport and bulk moduli using density functional theory. We also study the corresponding tin compounds Ca2Sn, Sr2Sn and Ba2Sn. We find that these are all narrow band gap semiconductors with an electronic structure favorable for thermoelectric performance, with substantial thermopowers for the lead compounds at temperature ranges from 300 to 800 K. For the lead compounds, we further find very low calculated bulk moduli—roughly half of the values for the lead chalcogenides, suggestive of soft phonons and hence low lattice thermal conductivity. All these facts indicate that these materials merit experimental investigation as potential high performance thermoelectrics. We find good potential for thermoelectric performance in the environmentally friendly stannide materials, particularly at high temperature.

  18. Fabrication and characterization of CH3NH3(Cs)Pb(Sn)I3(Br) perovskite solar cells

    Science.gov (United States)

    Ueoka, Naoki; Ohishi, Yuya; Shirahata, Yasuhiro; Suzuki, Atsushi; Oku, Takeo

    2017-01-01

    Perovskite-type CH3NH3(MA)PbI3-based photovoltaic devices were fabricated and characterized. Doping effects of cesium iodide (CsI), cesium bromide (CsBr) and tin bromide (SnBr2) on the photovoltaic properties and surface microstructures of the perovskite phase were investigated. Short-circuit current densities, open-circuit voltages and fill factors increased by CsI and SnBr2 addition. The surface coverage of the perovskite crystals was also improved by SnBr2 doping, which resulted in improvement of the fill factor. The cell prepared by a starting composition of MA0.95Cs0.05Pb0.95Sn0.05I2.90Br0.10 showed the best photovoltaic performance in the present work.

  19. $\\Lambda$ and $\\bar{\\Lambda}$ Production in Central Pb-Pb Collisions at 40, 80, and 158 A$\\cdot$GeV

    CERN Document Server

    Anticic, T; Collins, J; Dokshitzer, Y; Görlich, L; Grindhammer, G; Gustafson, G; Jönsson, L B; Jun, H; Kwiecinski, J; Levin, E; Lipatov, A V; Lönnblad, L; Lublinsk, M; Maul, M; Milcewicz, I; Miu, G; Nowak, G; Sjöstrand, Torbjörn; Stasto, A M; Timneanu, N; Turnau, J; Zotov, N P

    2003-01-01

    Production of Lambda and Antilambda hyperons was measured in central Pb-Pb collisions at 40, 80, and 158 A$\\cdot$GeV beam energy on a fixed target. Transverse mass spectra and rapidity distributions are given for all three energies. The $\\Lambda/\\pi$ ratio at mid-rapidity and in full phase space shows a pronounced maximum between the highest AGS and 40 A$\\cdot$GeV SPS energies, whereas the $\\bar{\\Lambda}/\\pi$ ratio exhibits a monotonic increase.

  20. Pion and kaon production in central Pb+Pb collisions at 20A and 30A GeV: Evidence for the onset of deconfinement

    CERN Document Server

    Alt, C; Baatar, B; Barna, D; Bartke, J; Betev, L; Bialkowska, H; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Buncic, P; Cerny, V; Christakoglou, P; Chung, P; Chvala, O; Cramer, J G; Csató, P; Dinkelaker, P; Eckardt, V; Flierl, D; Fodor, Z; Foka, P; Friese, V; Gál, J; Gazdzicki, M; Genchev, V; Georgopoulos, G; Gladysz-Dziadus, E; Grebieszkow, K; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kikola, D; Kliemant, M; Kniege, S; Kolesnikov, V I; Kollegger, T; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Laszlo, A; Lacey, R; Van Leeuwen, M; Lévai, Peter; Litov, L; Lungwitz, B; Makariev, M; Malakhov, A I; Mateev, M; Melkumov, G L; Mischke, A; Mitrovski, M; Molnár, J; Mrówczynski, S; Nicolic, V; Pálla, G; Panagiotou, A D; Panayotov, D; Petridis, A; Peryt, W; Pikna, M; Pluta, J; Prindle, D; Pühlhofer, F; Renfordt, R; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Schuster, T; Seyboth, P; Siklér, F; Sitár, B; Skrzypczak, E; Slodkowski, M; Stefanek, G; Stock, R; Strabel, C; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Szuba, M; Szymanski, P; Trubnikov, V; Varga, D; Vassiliou, M; Veres, G I; Vesztergombi, G; Vranic, D; Wetzler, A; Wlodarczyk, Z; Yoo, I K; Zimányi, J

    2008-01-01

    Results on charged pion and kaon production in central Pb+Pb collisions at 20A and 30A GeV are presented and compared to data at lower and higher energies. A rapid change of the energy dependence is observed around 30A GeV for the yields of pions and kaons as well as for the shape of the transverse mass spectra. The change is compatible with the prediction that the threshold for production of a state of deconfined matter at the early stage of the collisions is located at low SPS energies.

  1. Lambda and $\\overline{Lambda}$ production in central Pb-Pb collisions at 40, 80, and 158A GeV

    CERN Document Server

    Anticic, T; Barna, D; Bartke, Jerzy; Behler, M; Betev, L; Bialkowska, H; Billmeier, A; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Brun, R; Buncic, P; Cerny, V; Christakoglou, P; Chvala, O; Cramer, J G; Csató, P; Darmenov, N; Dimitrov, A; Dinkelaker, P; Eckardt, V; Filip, P; Flierl, D; Fodor, Z; Foka, P; Freund, P; Friese, V; Gál, J; Gazdzicki, M; Georgopoulos, G; Gladysz-Dziadus, E; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kolesnikov, V I; Kollegger, T; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Van Leeuwen, M; Lévai, Peter; Litov, L; Makariev, M; Malakhov, A I; Markert, C; Mateev, M; Mayes, B W; Melkumov, G L; Meurer, C; Mischke, A; Mitrovski, M; Molnár, J; Mrówczynski, S; Pálla, G; Panagiotou, A D; Panayotov, D; Perl, K; Petridis, A; Pikna, M; Pinsky, L; Pühlhofer, F; Reid, J G; Renfordt, R E; Retyk, W; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Sann, H; Schmitz, N; Seyboth, P; Siklér, F; Sitár, B; Skrzypczak, E; Stefanek, G; Stock, R; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Trainor, T A; Varga, D; Vassiliou, Maria; Veres, G I; Vesztergombi, G; Vranic, D; Wetzler, A; Wlodarczyk, Z; Yoo, I K; Zaranek, J; Zimányi, J

    2004-01-01

    Production of Lambda and Antilambda hyperons was measured in central Pb-Pb collisions at 40, 80, and 158A GeV beam energy on a fixed target. Transverse mass spectra and rapidity distributions are given for all three energies. The Lambda / pi ratio at midrapidity and in full phase space shows a pronounced maximum between the highest BNL Alternating Gradient Synchrotron and 40A GeV CERN Super Proton Synchrotron energies, whereas the Lambda / pi ratio exhibits a monotonic increase. (36 refs).

  2. Tensile strained Ge0.90Sn0.10 photodiode integrated with Si3N4 liner stressor for mid-infrared applications

    Science.gov (United States)

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

    2015-10-01

    In this paper, tensile strained Ge0.90Sn0.10 photodiode with different architectures integrated with Si3N4 liner stressor for mid-infrared applications are theoretically investigated. Ge0.90Sn0.10 fin and waveguide photodiodes wrapped in the Si3N4 liner stressor are designed and the strain distribution is studied by the finite element simulation. A large tensile strain is induced in Ge0.90Sn0.10 with the Si3N4 liner stressor expanding. The energy band structure of tensile strained Ge0.90Sn0.10 is calculated using kṡp theory. The direct bandgap Eg,Γ of Ge0.90Sn0.10 under tensile strain is significantly reduced, which results in a large red shift of the cut-off wavelength of strained Ge0.90Sn0.10 devices. As the Si3N4 liner stressor expands by 1.5%, 25.1% and 48.7% reduction of Eg,Γ are achieved in tensile strained Ge0.90Sn0.10 fin and waveguide photodiodes, respectively, compared to the unstrained device. The cut-off wavelengths of tensile strained Ge0.90Sn0.10 fin and waveguide devices are extended to 3.68 μm and 5.37 μm, respectively. Introducing tensile strain into GeSn by tensile strain liner stressor provides an effective method for extending the detection spectrum of GeSn photodiodes to mid-infrared wavelength, e.g. 5μm.

  3. Energy dependence of $\\phi$ meson production in central Pb+Pb collisions at $\\sqrt{s_{NN}}$=6 to 17 GeV

    CERN Document Server

    Alt, C; Baatar, B; Barna, D; Bartke, J; Betev, L; Bialkowska, H; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Buncic, P; Cerny, V; Christakoglou, P; Chung, P; Chvala, O; Cramer, J G; Csató, P; Dinkelaker, P; Eckardt, V; Flierl, D; Fodor, Z; Foka, P; Friese, V; Gál, J; Gazdzicki, M; Genchev, V; Georgopoulos, G; Galadysz, E; Grebieszkow, K; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kikola, D; Kliemant, M; Kniege, S; Kolesnikov, V I; Kollegger, T; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Kresan, D; Laszlo, A; Lacey, R; Van Leeuwen, M; Lévai, Peter; Litov, L; Lungwitz, B; Makariev, M; Malakhov, A I; Mateev, M; Melkumov, G L; Mischke, A; Mitrovski, M; Molnár, J; Mrówczynski, S; Nicolic, V; Pálla, G; Panagiotou, A D; Panayotov, D; Petridis, A; Peryt, W; Pikna, M; Pluta, J; Prindle, D; Pühlhofer, F; Renfordt, R; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Schuster, T; Seyboth, P; Siklér, F; Sitár, B; Skrzypczak, E; Slodkowski, M; Stefanek, G; Stock, R; Strabel, C; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Szuba, M; Szymanski, P; Trubnikov, V; Varga, D; Vassiliou, M; Veres, G I; Vesztergombi, G; Vranic, D; Wetzler, A; Walodarczyk, Z; Yoo, I K; Zimányi, J

    2008-01-01

    Phi meson production is studied by the NA49 collaboration in central Pb+Pb collisions at 20A, 30A, 40A, 80A and 158A GeV beam energy. The data are compared to measurements at lower and higher energies and to microscopic and thermal models. The energy dependence of yields and spectral distributions is compatible with the assumption that partonic degrees of freedom set in at low SPS energies.

  4. Mitigation and Verification Methods for Sn Whisker Growth in Pb-Free Automotive Electronics

    Science.gov (United States)

    Hong, Won Sik; Oh, Chul Min; Kim, Do Seop

    2013-02-01

    This work describes mitigation methods against Sn whisker growth in Pb-free automotive electronics using a conformal coating technique, with an additional focus on determining an effective whisker assessment method. We suggest effective whisker growth conditions that involve temperature cycling and two types of storage conditions (high-temperature/humidity storage and ambient storage), and analyze whisker growth mechanisms. In determining an efficient mitigation method against whisker growth, surface finish and conformal coating have been validated as effective means. In our experiments, the surface finish of components comprised Ni/Sn, Ni/SnBi, and Ni/Pd. The effects of acrylic silicone, and rubber coating of components were compared with uncoated performance under high-temperature/humidity storage conditions. An effective whisker assessment method during temperature cycling and under various storage conditions (high temperature/humidity and ambient) is indicated for evaluating whisker growth. Although components were finished with Ni/Pd, we found that whiskers were generated at solder joints and that conformal coating is a useful mitigation method in this regard. Although whiskers penetrated most conformal coating materials (acrylic, silicone, and rubber) after 3500 h of high-temperature/humidity storage, the whisker length was markedly reduced due to the conformal coatings, with silicone providing superior mitigation over acrylic and rubber.

  5. Anomalous band gap behavior in mixed Sn and Pb perovskites enables broadening of absorption spectrum in solar cells.

    Science.gov (United States)

    Hao, Feng; Stoumpos, Constantinos C; Chang, Robert P H; Kanatzidis, Mercouri G

    2014-06-04

    Perovskite-based solar cells have recently been catapulted to the cutting edge of thin-film photovoltaic research and development because of their promise for high-power conversion efficiencies and ease of fabrication. Two types of generic perovskites compounds have been used in cell fabrication: either Pb- or Sn-based. Here, we describe the performance of perovskite solar cells based on alloyed perovskite solid solutions of methylammonium tin iodide and its lead analogue (CH3NH3Sn(1-x)Pb(x)I3). We exploit the fact that, the energy band gaps of the mixed Pb/Sn compounds do not follow a linear trend (the Vegard's law) in between these two extremes of 1.55 and 1.35 eV, respectively, but have narrower bandgap (Pb ratio. Our results show that CH3NH3Sn(0.5)Pb(0.5)I3 has the broadest light absorption and highest short-circuit photocurrent density ~20 mA cm(-2) (obtained under simulated full sunlight of 100 mW cm(-2)).

  6. Characteristics of Sn-Doped Ge2Sb2Te5 Films Used for Phase-Change Memory

    Institute of Scientific and Technical Information of China (English)

    XU Cheng; LIU Bo; SONG Zhi-Tang; FENG Song-Lin; CHEN Bomy

    2005-01-01

    @@ Sn-doped Ge2Sb2 Te5 thin films deposited on Si(100)/SiO2 substrates by rf magnetron sputtering are investigatedby a differential scanning calorimeter, x-ray diffraction and sheet resistance measurement. The crystallizationtemperatures of the 3.58 at. %, 6.92 at. % and 10.04 at. % Sn-doped Ge2Sb2 Te5 thin films have decreases of 5.3,6.1 and 0.9 ℃, respectively, which is beneficial to reduce the switching current for the amorphous-to-crystallinephase transition. Due to Sn-doping, the sheet resistance of crystalline Ge2Sb2 Te5 thin films increases about 2-10times, which may be useful to reduce the switching current for the amorphous-to-crystalline phase change. Inaddition, an obvious decreasing dispersibility for the sheet resistance of Sn-doped Ge2Sb2 Te5 thin films in thecrystalline state has been observed, which can play an important role in minimizing resistance difference for thephase-change memory cell element arrays.

  7. Crystal structure and magnetic properties of GdCo{sub 6}X{sub 6} (X=Ge, Sn) and TbCo{sub 6}Ge{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Szytula, A.; Wawrzynska, E.; Zygmunt, A

    2004-03-10

    Crystal structures of the YCo{sub 6}Ge{sub 6}-type for GdCo{sub 6}X{sub 6} (X=Ge, Sn) and TbCo{sub 6}Ge{sub 6} are determined by X-ray diffraction. The magnetic data indicates that GdCo{sub 6}Ge{sub 6} is an antiferromagnet with a Neel temperature equal to 3 K while GdCo{sub 6}Sn{sub 6} and TbCo{sub 6}Ge{sub 6} are paramagnetic down to 1.8 K.

  8. Study of Neutrons in Thick Pb Target Bombarded by 0.65~1.5 GeV Protons

    Institute of Scientific and Technical Information of China (English)

    R.Brandt; P.Vater; W.Westmeier; B.A.Kulakov; M.I.Krivopustov; A.N.Sosnin

    2001-01-01

    Study of neutrons has been carried out at thick Pb target bombarded with 0.65, 1.0 and 1.5 GeV protons from the accelerator NUCLOTRON newly built in the Joint Institute for Nuclear Research (JINR), Dubna, Russia. The Pb target is 20 cm in thickness and 8 cm in diameter. Outside the Pb target, paraffin of 6 cm in thickness is used as moderator. Proton beam from the accelerator impinged on the cylindric Pb target along its axis. The above arrangement is to simulate the core structure and nuclear reaction process of an accelerator-driven subcritical nuclear reactor. CR-39 nuclear track detector strips

  9. Disorder-induced enhancement of indirect absorption in a GeSn photodetector grown by molecular beam epitaxy

    Science.gov (United States)

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

    2016-05-01

    We report an investigation on the absorption mechanism of a GeSn photodetector with 2.4% Sn composition in the active region. Responsivity is measured and absorption coefficient is calculated. Square root of absorption coefficient linearly depends on photon energy indicating an indirect transition. However, the absorption coefficient is found to be at least one order of magnitude higher than that of most other indirect materials, suggesting that the indirect optical absorption transition cannot be assisted only by phonon. Our analysis of absorption measurements by other groups on the same material system showed the values of absorption coefficient on the same order of magnitude. Our study reveals that the strong enhancement of absorption for the indirect optical transition is the result of alloy disorder from the incorporation of the much larger Sn atoms into the Ge lattice that are randomly distributed.

  10. Removal of the pesticide methamidophos from aqueous solutions by electrooxidation using Pb/PbO2, Ti/SnO2, and Si/BDD electrodes.

    Science.gov (United States)

    Martínez-Huitle, Carlos A; De Battisti, Achille; Ferro, Sergio; Reyna, Silvia; Cerro-López, Mónica; Quiro, Marco A

    2008-09-15

    The anodic oxidation of methamidophos (MMD), a highly toxic pesticide used worldwide, was studied in a sodium sulfate aqueous solution on Pb/PbO2, Ti/SnO2, and Si/BDD (boron doped diamond) electrodes at 30 degrees C. Under galvanostatic conditions, it was observed thatthe performance of the electrode material is influenced by pH and current density as shown by HPLC and ATR-FTIR analysis of MMD and its oxidation products along the electrolysis. It was found that MMD degradation using Pb/PbO2 in acid media (pH 2.0 and 5.6) generates formaldehyde asthe main product of the reaction giving evidence of an indirect mineralization mechanism. Under the same conditions, Ti/SnO2 showed poor formaldehyde production compared to the Pb/PbO2 electrode. On Si/BDD electrodes formaldehyde production was not observed, instead the ATR-FTIR results showed the formation of phosphate as the reaction progressed suggesting a complete MMD mineralization on this electrode. In addition, HPLC results showed that the electrode efficiency is also dependent on the applied current density. This current density influence is remarkably clear on the Si/BDD electrodes where it was evident that the most efficient current density toward a complete MMD mineralization was reached with the application of 50 mA/cm2.

  11. Study of the structural, electrical and optical properties of Ge-Pb-Te nanocrystals

    Science.gov (United States)

    Mahdy, Iman A.; Mahdy, Manal A.; El Sheikh, S. M.

    2016-12-01

    Nanocrystals of Pb37.5Ge12.5Te50 with average size 24 nm are prepared using direct solid state reactions of pure elements in vacuum. The obtained Pb37.5Ge12.5Te50 nanocrystal alloy was used as a starting material for preparing thin films by inert gas condensation (IGC) technique. The obtained thin films show a nanocrystalline structure. Particle size of thin film increases from 4.3 to 6.9 nm with increasing film thickness from 10 to 60 nm. Optical studies for thin films revealed a direct allowed electronic transition. The values of optical band gap E op g decreased from 2.26 to 1.63 eV with increasing film thickness from 10 to 60 nm and inversely proportional to particle size. The electrical conductivity of nanocrystalline thin films was enhanced by a factor of 1000 times with increasing film thickness from 10 to 60 nm. The reduction of electrical conductivity during cooling cycle for 46 and 60 nm film thicknesses can be explained by the so-called core-shell model. The growth of crystal during heating process causes an increase in thin film resistance during cooling which reduces the probability of the presence of current paths within thin film.

  12. Experimental studies of an In/Pb binary surface alloy on Ge(111)

    Science.gov (United States)

    Sohail, Hafiz M.; Uhrberg, R. I. G.

    2016-07-01

    In this study, we present a binary In/Pb surface alloy on Ge(111) formed by evaporating In on the Pb/Ge(111)√{ 3} ×√{ 3} β phase. A well-defined 3 × 3 periodicity is formed after annealing, as verified by both low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). Overview STM images show a clear 3 × 3 periodicity. Detailed STM images reveal protrusions corresponding to atomic sized features with a local hexagonal arrangement. Each 3 × 3 unit cell contains nine such features indicating a structure with 9 atoms per 3 × 3 cell in the topmost layer. Based on angle resolved photoelectron spectroscopy (ARPES) data, we have identified five surface bands within the bulk band gap. Four of them cross the Fermi level leading to a metallic character of the surface. The dispersions of these bands have been mapped in detail along two high symmetry directions of the surface Brillouin zone. Constant energy contours, mapped in two dimensional k-space, show interesting features. In particular, the occurrence of two differently rotated hexagon-like contours is presented.

  13. Strange particle production in [sup 32]S+Pb and p+Pb collisions at 200 GeV/c per nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, F.; Loevhoeiden, G.; Thorsteinsen, T.F. (Univ. Bergen, Dept. of Physics (Norway)); Barnes, P.D.; Diebold, G.E.; Franklin, G.; Quinn, B. (Carnegie-Mellon Univ., Dept. of Physics, Pittsburgh, PA (United States)); Blaes, R.; Geist, W.M.; Hafidouni, M.; Ladrem, M.; Voltolini, C. (Centre de Recherches Nucleaires, IN2P3-CNRS, Univ. L. Pasteur, 67 - Strasbourg (France)); Cherney, M. (Creighton Univ., Dept. of Physics, Omaha, NE (United States)); Cruz, B. de la; Ladron de Guevara, P.; Perez de los Heros, C. (CIEMAT, Div. de Fisica de Particulas, Madrid (Spain)); Dulny, B.; Natkaniec, Z.; Wozniak, K. (Inst. Fizyki Jadrowej, Cracow (Poland)); Fernandez, C.; Garabatos, C.; Garzon, J.A.; Plo, M.; Yanez, A. (Univ. Santiago, Dept. de Fisica de Particulas, Santiago de Compostela (Spain)); Hrubec, J.; MacNaughton, J.; Neuhofer, G.; Porth, P.; Rohringer, H.; Traxler, J. (Inst. fuer Hochenergiephysik, HEPHY, Vienna (Austria)); Jones, P.G.; Judd, E.G.; Nelson, J.M.; Zybert, R. (Univ. Bi; NA36 Collaboration

    1993-03-01

    Cross sections for [Lambda], anti [Lambda], and Kdeg production in S+Pb reaction at 200 GeV/c/n have been measured. Transverse momentum and rapidity distributions as well as the production dependence on event multiplicity are presented. An enhancement of strangeness production in mid-rapidity is observed. (orig.).

  14. Characterization of Ag-Ge-Se bulk glasses by means of Moessbauer effect on {sup 57}Fe and {sup 119}Sn atomic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Arcondo, B; Urena, M A; Garrido, J M Conde; Rocca, J A; Fontana, M, E-mail: barcond@fi.uba.a [Laboratorio de Solidos Amorfos, INTECIN, Facultad de IngenierIa, Universidad de Buenos Aires-CONICET (Argentina)

    2010-03-01

    In this work, the structure of Fe and Sn doped Ag{sub x}(Ge{sub 0.25}Se{sub 0.75}){sub 100-x} (x=0 to 25 at.%) intrinsically inhomogeneous glasses is analyzed employing {sup 119m}Sn and {sup 57}Fe Moessbauer spectroscopy, X-ray diffractometry and scanning electron microscopy. {sup 119m}Sn enters in the glass as a substitutional impurity for Ge whereas {sup 57}Fe enters as an interstitial impurity. Moessbauer spectra obtained with {sup 119m}SnO{sub 3}Ca source, from samples containing about 1% {sup 119}Sn for Ge, reveal that the local order of Ge in both amorphous phases is basically the same whereas Moessbauer spectra obtained with {sup 57}Fe(Rh) source, from samples containing about 0.5% {sup 57}Fe, evidence the differences between both phases.

  15. Electronic, structural, and magnetic properties of the quaternary Heusler alloy NiCoMnZ (Z=Al, Ge, and Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Halder, Madhumita, E-mail: mhalder@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Mukadam, M.D. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Suresh, K.G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Yusuf, S.M. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2015-03-01

    The electronic, magnetic, and structural properties of the Heusler alloys NiCoMnZ (Z=Al, Ge, and Sn) have been investigated both theoretically and experimentally. NiCoMnGe and NiCoMnSn have ordered cubic Heusler structure (with a possible disorder between Ni and Co), while NiCoMnAl has a B2 type disordered Heusler structure with random occupancy between Mn and Al atom at their crystallographic sites. Electronic structure calculation shows that NiCoMnGe and NiCoMnSn are normal ferromagnets, whereas NiCoMnAl is nearly half metallic (∼100% spin polarization) in nature with its magnetic moment close to an integer value following the Slater–Pauling rule. Ab-initio calculations show ∼56% and ∼60% spin polarization for NiCoMnGe and NiCoMnSn, respectively. Magnetization measurements show all the three compounds have a high Curie temperature (>583 K). - Highlights: • Electronic, magnetic, and structural properties of Heusler alloys NiCoMnZ (Z=Al, Ge, and Sn) have been investigated. • NiCoMnGe and NiCoMnSn are normal ferromagnets, while NiCoMnAl is nearly half metallic. • All the three compounds have a high Curie temperature. • NiCoMnGe and NiCoMnSn have ordered cubic structure; while NiCoMnAl has a B2 type disordered structure.

  16. Spin-orbit coupling effects on the stability of two competing structures in Pb/Si(111) and Pb/Ge(111)

    CERN Document Server

    Ren, Xiao-Yan; Yi, Seho; Jia, Yu; Cho, Jun-Hyung

    2016-01-01

    Using first-principles density-functional theory (DFT) calculations, we investigate the 4/3-monolayer structure of Pb on the Si(111) or Ge(111) surface within the two competing structural models termed the H$_3$ and T$_4$ structures. We find that the spin-orbit coupling (SOC) influences the relative stability of the two structures in both the Pb/Si(111) and Pb/Ge(111) systems: i.e., our DFT calculation without including the SOC predicts that the T$_4$ structure is energetically favored over the H$_3$ structure by ${\\Delta}E$ = 25 meV for Pb/Si(111) and 22 meV for Pb/Ge(111), but the inclusion of SOC reverses their relative stability as ${\\Delta}E$ = $-$12 and $-$7 meV, respectively. Our analysis shows that the SOC-induced switching of the ground state is attributed to a more asymmetric surface charge distribution in the H$_3$ structure, which gives rise to a relatively larger Rashba spin splitting of surface states as well as a relatively larger pseudo-gap opening compared to the T$_4$ structure. By the nudge...

  17. Atomic and electronic structure of the (2√(3)×2√(3))R30° strained Sn reconstruction on Ge/Si(1 1 1)

    Energy Technology Data Exchange (ETDEWEB)

    Srour, W. [Université de Lorraine, UMR CNRS 7198, Institut Jean Lamour, BP 70239, F-54506 Vandoeuvre-lès-Nancy (France); Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette (France); Tejeda, A., E-mail: antonio.tejeda@u-psud.fr [Laboratoire de Physique des Solides, Université Paris-Sud, CNRS, UMR 8502, F-91405 Orsay (France); Stoffel, M. [Université de Lorraine, UMR CNRS 7198, Institut Jean Lamour, BP 70239, F-54506 Vandoeuvre-lès-Nancy (France); Abuín, M. [Dto. de Física de Materiales, Universidad Complutense de Madrid, 28040 Madrid (Spain); Fagot-Revurat, Y. [Université de Lorraine, UMR CNRS 7198, Institut Jean Lamour, BP 70239, F-54506 Vandoeuvre-lès-Nancy (France); Fèvre, P. Le [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette (France); Taleb-Ibrahimi, A. [UR1 CNRS/Synchrotron SOLEIL, Saint-Aubin, 91192 Gif sur Yvette (France); Malterre, D. [Université de Lorraine, UMR CNRS 7198, Institut Jean Lamour, BP 70239, F-54506 Vandoeuvre-lès-Nancy (France)

    2014-08-15

    Highlights: • We find a new Sn reconstruction on strained Ge/Si(1 1 1). • Its coverage differs from that of Sn/Si(1 1 1) and Sn/Ge(1 1 1) exhibiting Mott phases. • The band structure reveals it is a band insulator. - Abstract: Motivated by the different behaviour of Sn/Si(1 1 1) and Sn/Ge(1 1 1) in their metal-insulator transition, we have explored the possibility of growing Sn on an ultra-thin Ge layer strained on top of a Si(1 1 1) substrate. We have demonstrated by scanning tunneling microscopy and low energy electron diffraction that a (2√(3)×2√(3))R30° reconstruction can be stabilized under adequate growth conditions. The size of the reconstructed domains increases progressively up to a coverage of 1.3 monolayer of Sn, as determined by a combined study of scanning tunneling microscopy and core level spectroscopy. This coverage differs from that of Sn/Si(1 1 1) and Sn/Ge(1 1 1) exhibiting Mott phases. Angle resolved photoemission shows that the highly strained reconstruction is a band insulator, with a surface state dispersing roughly between 1300 and 2300 meV of binding energy.

  18. Assessing the toxicity of Pb- and Sn-based perovskite solar cells in model organism Danio rerio.

    Science.gov (United States)

    Babayigit, Aslihan; Duy Thanh, Dinh; Ethirajan, Anitha; Manca, Jean; Muller, Marc; Boyen, Hans-Gerd; Conings, Bert

    2016-01-13

    Intensive development of organometal halide perovskite solar cells has lead to a dramatic surge in power conversion efficiency up to 20%. Unfortunately, the most efficient perovskite solar cells all contain lead (Pb), which is an unsettling flaw that leads to severe environmental concerns and is therefore a stumbling block envisioning their large-scale application. Aiming for the retention of favorable electro-optical properties, tin (Sn) has been considered the most likely substitute. Preliminary studies have however shown that Sn-based perovskites are highly unstable and, moreover, Sn is also enlisted as a harmful chemical, with similar concerns regarding environment and health. To bring more clarity into the appropriateness of both metals in perovskite solar cells, we provide a case study with systematic comparison regarding the environmental impact of Pb- and Sn-based perovskites, using zebrafish (Danio Rerio) as model organism. Uncovering an unexpected route of intoxication in the form of acidification, it is shown that Sn based perovskite may not be the ideal Pb surrogate.

  19. Assessing the toxicity of Pb- and Sn-based perovskite solar cells in model organism Danio rerio

    Science.gov (United States)

    Babayigit, Aslihan; Duy Thanh, Dinh; Ethirajan, Anitha; Manca, Jean; Muller, Marc; Boyen, Hans-Gerd; Conings, Bert

    2016-01-01

    Intensive development of organometal halide perovskite solar cells has lead to a dramatic surge in power conversion efficiency up to 20%. Unfortunately, the most efficient perovskite solar cells all contain lead (Pb), which is an unsettling flaw that leads to severe environmental concerns and is therefore a stumbling block envisioning their large-scale application. Aiming for the retention of favorable electro-optical properties, tin (Sn) has been considered the most likely substitute. Preliminary studies have however shown that Sn-based perovskites are highly unstable and, moreover, Sn is also enlisted as a harmful chemical, with similar concerns regarding environment and health. To bring more clarity into the appropriateness of both metals in perovskite solar cells, we provide a case study with systematic comparison regarding the environmental impact of Pb- and Sn-based perovskites, using zebrafish (Danio Rerio) as model organism. Uncovering an unexpected route of intoxication in the form of acidification, it is shown that Sn based perovskite may not be the ideal Pb surrogate. PMID:26759068

  20. Assessing the toxicity of Pb- and Sn-based perovskite solar cells in model organism Danio rerio

    Science.gov (United States)

    Babayigit, Aslihan; Duy Thanh, Dinh; Ethirajan, Anitha; Manca, Jean; Muller, Marc; Boyen, Hans-Gerd; Conings, Bert

    2016-01-01

    Intensive development of organometal halide perovskite solar cells has lead to a dramatic surge in power conversion efficiency up to 20%. Unfortunately, the most efficient perovskite solar cells all contain lead (Pb), which is an unsettling flaw that leads to severe environmental concerns and is therefore a stumbling block envisioning their large-scale application. Aiming for the retention of favorable electro-optical properties, tin (Sn) has been considered the most likely substitute. Preliminary studies have however shown that Sn-based perovskites are highly unstable and, moreover, Sn is also enlisted as a harmful chemical, with similar concerns regarding environment and health. To bring more clarity into the appropriateness of both metals in perovskite solar cells, we provide a case study with systematic comparison regarding the environmental impact of Pb- and Sn-based perovskites, using zebrafish (Danio Rerio) as model organism. Uncovering an unexpected route of intoxication in the form of acidification, it is shown that Sn based perovskite may not be the ideal Pb surrogate.

  1. Ge(001)-(<2 1>, <0 3>)-Pb(<2 1>, <0 6>)↔Pb: Low-temperature two-dimensional phase transition

    DEFF Research Database (Denmark)

    Bunk, Oliver; Nielsen, Martin Meedom; Zeysing, J.H.;

    2001-01-01

    The Ge(001)-((2 1)(0 3))-Pb surface reconstruction with a lead coverage of 5/3 monolayer is on the borderline between the low-coverage covalently-bonded and high-coverage metallic lead overlayers. This gives rise to an unusual low-temperature phase transition with concomitant changes in the bonding...... configuration. Both the room-temperature and low-temperature phases of this system were investigated by surface x-ray diffraction using synchrotron radiation. The room-temperature Ge(001)-((2 1)(0 3)) phase is best described by a model with dynamically flipping germanium dimers underneath a distorted Pb(111......) overlayer with predominantly metallic properties. In the low-temperature Ge(001)-((2 1)(0 6)) phase the dimers are static and the interaction between adsorbate and substrate and within the adsorbate is stronger than at room temperature. These results suggest that the phase transition is of order...

  2. Solvothermal preparation and thermoelectric properties of quasi-binary Sn(Pb)Te-Bi2Te3 compounds

    Institute of Scientific and Technical Information of China (English)

    周西松; 邓元; 韦国丹; 刘静; 南策文

    2003-01-01

    Bulk samples of quasi-binary compounds in the Sn(Pb)Te-Bi2Te3 system were prepared by solvothermal method followed by a sintering procedure of compacted pellets. The formation mechanism of the precursor powders, microstructure and thermoelectric properties of the final bulk samples were studied.

  3. Shell-model calculations in 132Sn and 208Pb regions with low-momentum interactions

    CERN Document Server

    Gargano, A; Covello, A; Itaco, N

    2009-01-01

    We discuss shell-model calculations based on the use of low-momentum interactions derived from the free-space nucleon-nucleon potential. A main feature of this approach is the construction of a smooth potential, V-low-k, defined within a given momentum cutoff. As a practical application of the theoretical framework, we present some selected results of our current study of nuclei around doubly magic 132Sn and 208Pb which have been obtained starting from the CD-Bonn potential. Focusing attention on the similarity between the spectroscopy of these two regions, we show that it emerges quite naturally from our effective interactions without use of any adjustable parameter.

  4. Development of heat resistant Pb-free joints by TLPS process of Ag and Sn-Bi-Ag alloy powders

    Directory of Open Access Journals (Sweden)

    Ohnuma I.

    2012-01-01

    Full Text Available TLPS (Transient Liquid Phase Sintering process is a candidate method of heat-resistant bonding, which makes use of the reaction between low-melting temperature powder of Sn-Bi base alloys and reactive powder of Ag. During heat treatment above the melting temperature of a Sn-Bi base alloy, the molten Sn-Bi reacts rapidly with solid Ag particles, which results in the formation of heat-resistant intermetallic compound (IMC. In this study, the TLPS properties between Sn-17Bi-1Ag (at.% powder with its liquidus temperature of 200°C and pure Ag powder were investigated. During differential scanning calorimetry (DSC measurement, an exothermic reaction and an endothermic reaction occurred, which correspond to the formation of the e-Ag3Sn IMC phase and the melting of the Sn-17Bi-1Ag alloy, respectively. After the overall measurement, the obtained reactant consists of the Ag3Sn-IMC and Bi-rich phases, both of which start melting above 250°C, with a small amount of the residual Sn-Bi eutectic phase. These results suggest that the TLPS process can be applied for Pb-free heatresistant bonding.

  5. Structural and Optical Characteristics of GeSn Quantum Wells for Silicon-Based Mid-Infrared Optoelectronic Applications

    Science.gov (United States)

    Dou, Wei; Ghetmiri, Seyed Amir; Al-Kabi, Sattar; Mosleh, Aboozar; Zhou, Yiyin; Alharthi, Bader; Du, Wei; Margetis, Joe; Tolle, John; Kuchuk, Andrian; Benamara, Mourad; Li, Baohua; Naseem, Hameed A.; Mortazavi, Mansour; Yu, Shui-Qing

    2016-12-01

    This paper reports the study of Ge0.95Sn0.05/Ge0.91Sn0.09/Ge0.95Sn0.05 single quantum well (SQW) and double quantum wells (DQWs). The quantum well (QW) structures were grown on Ge buffered Si substrates using an industrial standard reduced-pressure chemical vapor deposition system. Pseudomorphically grown structures were observed using x-ray diffraction measurements. Defect-free interfaces between each layer were revealed using cross-sectional transmission electron microscopy. Atomic-scale high-resolution transmission electron microscopy and Fourier transform patterns exhibited the high crystalline quality of QWs. Temperature-dependent photoluminescence (PL) was performed, and the emission peaks attributed to the QW region were identified. The dominant optical transition changed from direct bandgap transition at 300 K to indirect bandgap transition at 10 K. Theoretical calculation showed the type-I band alignment for the QWs. Moreover, the Γ and L valley electron distributions and non-radiative lifetimes were evaluated, which further explained the PL characteristics of the QW samples.

  6. Magnetic structures and physical properties of Tm3Cu4Ge4 and Tm3Cu4Sn4.

    Science.gov (United States)

    Baran, S; Kaczorowski, D; Szytuła, A; Gil, A; Hoser, A

    2013-02-13

    Tm(3)Cu(4)Ge(4) crystallizes in the orthorhombic Gd(3)Cu(4)Ge(4)-type crystal structure (space group Immm) whereas Tm(3)Cu(4)Sn(4) crystallizes in a distorted variant of this structure (monoclinic space group C2/m). The compounds were studied by means of neutron diffraction, specific heat, electrical resistivity and magnetic measurements. Analysis of experimental data revealed the presence of an antiferromagnetic order below 2.8 K in both compounds. In Tm(3)Cu(4)Ge(4) the magnetic unit cell is doubled in respect to the crystal unit cell and the magnetic structure can be described by a propagation vector k = [0, 1/2, 0]. A larger magnetic unit cell was found in Tm(3)Cu(4)Sn(4), given by a propagation vector k = [1/2, 1/2, 0] (for simplicity the orthorhombic description is used for both the germanide and the stannide). Close to 2 K, in each compound an incommensurate antiferromagnetic order develops. This low-temperature magnetic phase is characterized by a propagation vector k = [1/4, 0, k(z)], where k(z) is close to 0.49 and 0.47 in Tm(3)Cu(4)Ge(4) and Tm(3)Cu(4)Sn(4), respectively. The antiferromagnetic phase transitions are clearly seen in the bulk magnetic and specific heat data of both compounds.

  7. All-epitaxial Co{sub 2}FeSi/Ge/Co{sub 2}FeSi trilayers fabricated by Sn-induced low-temperature epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, M.; Ikawa, M.; Arima, K.; Yamada, S.; Kanashima, T.; Hamaya, K., E-mail: hamaya@ee.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka 560-8531 (Japan)

    2016-01-28

    We demonstrate low-temperature growth of all-epitaxial Co{sub 2}FeSi/Ge/Co{sub 2}FeSi trilayer structures by developing Sn-induced surfactant-mediated molecular beam epitaxy (SMBE) of Ge on Co{sub 2}FeSi. Despite the growth of a semiconductor on a metal, we verify that the inserted Sn monolayers between Ge and Co{sub 2}FeSi enable to promote the 2D epitaxial growth of Ge up to 5 nm at a T{sub G} of 250 °C. An understanding of the mechanism of the Sn-induced SMBE leads to the achievement of all-epitaxial Co{sub 2}FeSi/Ge/Co{sub 2}FeSi trilayer structures with spin-valve-like magnetization reversals. This study will open a way for vertical-type and high-performance Ge-based spintronics devices.

  8. Coordination Chemistry of [E(Idipp)]2+ Ligands (E = Ge, Sn): Metal Germylidyne [Cp*(CO)2W≡Ge(Idipp)]+ and Metallotetrylene [Cp*(CO)3W–E(Idipp)]+ Cations

    KAUST Repository

    Lebedev, Yury

    2017-04-12

    The synthesis and full characterization of the NHC-stabilized tungstenochlorostannylene [Cp*(CO)3W–SnCl(Idipp)] (1Sn), the NHC-stabilized chlorogermylidyne complex [Cp*(CO)2W═GeCl(Idipp)] (2), the tungsten germylidyne complex salt [Cp*(CO)2W≡Ge(Idipp)][B(C6H3-3,5-(CF3)2)4] (3), and the cationic metallostannylene [Cp*(CO)3W–Sn(Idipp)][Al(OC(CF3)3)4] (4Sn) are reported (Idipp = 2,3-dihydro-1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-2-ylidene, Cp* = η5-C5Me5). Metathetical exchange of SnCl2(Idipp) with Li[Cp*W(CO)3] afforded selectively 1Sn. Photolytic decarbonylation of the Ge analogue [Cp*(CO)3W–GeCl(Idipp)] (1Ge) afforded the NHC-stabilized chlorogermylidyne complex (2), featuring a trigonal-planar coordinated germanium center and a W–Ge double bond (W–Ge 2.3496(5) Å). Chloride abstraction from 2 with Na[B(C6H3-3,5-(CF3)2)4] yielded the germylidyne complex salt 3, which contains an almost linear W–Ge–C1 linkage (angle at Ge = 168.7(1)°) and a W–Ge triple bond (2.2813(4) Å). Chloride elimination from 1Ge afforded the tungstenogermylene salt [Cp*(CO)3W–Ge(Idipp)][B(C6H3-3,5-(CF3)2)4] (4Ge), which in contrast to 1Ge could not be decarbonylated to form 3 despite the less strongly bound carbonyl ligands. The tin compounds 1Sn and 4Sn did not afford products bearing multiple W–Sn bonds. Treatment of 4Ge with Me2NC≡CNMe2 yielded unexpectedly the neutral germyl complex 5 containing a pendant 1-germabicyclo-[3,2,0]-hepta-2,5-diene ligand instead of the anticipated [2 + 1]-cycloaddition product at the Ge-center.

  9. 119Sn-Mössbauer spectroscopic study of the single phase of Bi(Pb) sbnd Sr sbnd Ca sbnd Cu(Sn) sbnd O

    Science.gov (United States)

    Matsumoto, Y.; Nishida, T.; Katada, M.; Deshimaru, Y.; Miura, N.; Yamazoe, N.

    Tin-doped samples of the high- Tc (2223) phase of Bi sbnd Pb sbnd Sr sbnd Ca sbnd Cu sbnd O superconductor have been prepared by a conventional sintering method. Sintering conditions were carefully selected to obtain the single high- Tc phase. 119Sn-Mössbauer spectra have been measured in the temperature range from 4.2 to 300 K. The temperature dependence of the recoilless fraction ( f) is well understood by the temperature dependence of the normal phonon.

  10. Radioisotope Thermoelectric Generators Based on Segmented BiTe/PbTe-BiTe/TAGS/PbSnTe

    Science.gov (United States)

    McAlonan, Malachy; Patel, Kalpesh; Cummer, Keith

    2006-01-01

    This paper reports on Phase 1 of a multifaceted effort to develop a more efficient radioisotope thermoelectric generator (RTG) for future NASA missions. The conversion efficiency goal is 10% or higher at a power level of 20 watt or higher. The thermoelectric (T/E) efficiency achievable with present T/E materials is about 8% for favorable temperatures. Thermoelectric converter designs, T/E material properties, and T/E couple thermal and electrical performance were investigated in Phase 1 of this program to find paths to improve conversion efficiency. T/E properties can be improved by optimizing the composition of the materials and by improving the micro structural characteristics such as homogeneity, grain size, and phases present. T/E couple performance can be improved by reducing the electrical and thermal contact resistances of the couple and within the segmented T/E elements. Performance and reliability improvements can be achieved by reducing the thermo-mechanical stresses, improving the quality of the bonds and interfaces, minimizing the number of required bonds, and reducing the degradation rates of both the T/E materials and the bonds. This paper focuses on one portion of the activity, i.e., the design of a small converter. In the converter design effort, a prototypic 20-watt device, suitable for use with a single general-purpose heat source (GPHS), was built using an optimized converter design of segmented thermoelectric elements of heritage composition. The 20-watt prototype achieved the power predicted for the test conditions. The chosen couple design used segmented BiTe/PbTe for the n-type element and BiTe/TAGS/PbSnTe, for the p-type T/E element. Use of the BiTe segment exploits the opportunity of the small RTG to operate at lower heat rejection temperatures and results in much higher conversion efficiency, the main objective of the NASA program. Long term data on similarly segmented couples at Teledyne together with the 20-watt module test results

  11. Theoretical insights into a potential lead-free hybrid perovskite: substituting Pb(2+) with Ge(2.).

    Science.gov (United States)

    Sun, Ping-Ping; Li, Quan-Song; Yang, Li-Na; Li, Ze-Sheng

    2016-01-21

    In recent years, perovskite solar cells have been considerably developed, however the lead in the absorber MAPbI3 is a potential threat to the environment. To explore potential alternatives, the structural and electronic properties of MAGeX3 (X = Cl, Br, I) were investigated using different density functional theory methods, including GGA-PBE, PBE-SOC, HSE06 and HSE-SOC. The results implied that MAGeI3 exhibits an analogous band gap, substantial stability, remarkable optical properties, and significant hole and electron conductive behavior compared with the so far widely used absorber MAPbI3. Moreover, the calculations revealed that the energy splitting resulting from the spin-orbit coupling is evident on Pb, moderate on Ge, I and Br, and negligible on Cl. Our work not only sheds some light on screening novel absorbers for perovskite solar cells but also deepens the understanding of these functional materials.

  12. Electromagnetic calorimetry with $PbWO^{4}$ in the energy regime below 1 GeV

    CERN Document Server

    Novotny, R; Döring, W; Hejny, V; Hofstäetter, A; Korzhik, M V; Metag, V; Ströher, H

    2000-01-01

    The study of the performance and application of PbWO/sub 4/ in electromagnetic calorimetry at energies far below 1 GeV has been continued. The significantly improved optical and scintillation properties of 15 cm long Nb/La-doped crystals, optimized for the ECAL /CMS calorimeter, are documented. The lineshape, energy and time response of a 5*5 matrix are tested with monoenergetic photons up to 790 MeV energy and compared to previous measurements. First attempts have been made to enhance the scintillation yield by suitable dopants (Mo, Tb) for applications at very low photon energies. As a first large scale project at medium energies, the proposed concept for a compact photon spectrometer to be implemented into the ANKE magnetic spectrometer at COSY (KFA Julich) is illustrated. (4 refs).

  13. Electromagnetic calorimetry with $PbWO_{4}$ in the energy regime below 1 GeV

    CERN Document Server

    Novotny, R; Döring, W; Hejny, V; Hofstäetter, A; Korzhik, M V; Metag, V; Ströher, H

    1999-01-01

    The study of the performance and application of PbWO/sub 4/ in electromagnetic calorimetry at energies far below 1 GeV has been continued. The significantly improved optical and scintillation properties of 15 cm long Nb/La-doped crystals, optimized for the ECAL /CMS calorimeter, are documented. The lineshape, energy and time response of a 5*5 matrix are tested with monoenergetic photons up to 790 MeV energy and compared to previous measurements. First attempts have been made to enhance the scintillation yield by suitable dopants (Mo, Tb) for applications at very low photon energies. As a first large scale project at medium energies, the proposed concept for a compact photon spectrometer to be implemented into the ANKE magnetic spectrometer at COSY (KFA Julich) is illustrated. (2 refs).

  14. Electrochemical degradation of nitrobenzene by anodic oxidation on the constructed TiO2-NTs/SnO2-Sb/PbO2 electrode.

    Science.gov (United States)

    Chen, Yong; Li, Hongyi; Liu, Weijing; Tu, Yong; Zhang, Yaohui; Han, Weiqing; Wang, Lianjun

    2014-10-01

    The interlayer of Sb-doped SnO2 (SnO2-Sb) and TiO2 nanotubes (TiO2-NTs) on Ti has been introduced into the PbO2 electrode system with the aim to reveal the mechanism of enhanced electrochemical performance of TiO2-NTs/SnO2-Sb/PbO2 electrode. In contrast with the traditional Ti/SnO2-Sb/PbO2 electrode, the constructed PbO2 electrode has a more regular and compact morphology with better oriented crystals of lower size. The TiO2-NTs/SnO2-Sb interlayer prepared by electrodeposition process improves PbO2 coating structure effectively, and enhances the electrochemical performance of PbO2 electrode. Kinetic analyses indicated that the electrochemical oxidation of nitrobenzene on the PbO2 electrodes followed pseudo-first-order reaction, and mass transport was enhanced at the constructed electrode. The accumulation of nitrocompounds of degradation intermediates on constructed electrode was lower, and almost all of the nitro groups were eliminated from aromatic rings after 6h of electrolysis. Higher combustion efficiency was obtained on the constructed TiO2-NTs/SnO2-Sb/PbO2 electrode. The intermediates of nitrobenzene oxidation were confirmed by IC and GC/MS.

  15. First-principles study of defect formation in the photovoltaic semiconductors Cu2GeS3 and Cu2ZnGeS4 for comparison with Cu2SnS3, Cu2ZnSnS4, and CuInSe2

    Science.gov (United States)

    Nishihara, Hironori; Maeda, Tsuyoshi; Shigemi, Akio; Wada, Takahiro

    2017-04-01

    The formation energies of neutral Cu, Ge, and S vacancies in monoclinic Cu2GeS3 and those of neutral Cu, Zn, Ge, and S vacancies in kesterite-type Cu2ZnGeS4 were evaluated by first-principles pseudopotential calculations using plane-wave basis functions. The calculations were performed at typical points in a schematic ternary phase diagram of a Cu-Ge-S system for Cu2GeS3 and in Cu-(Zn1/2Ge1/2)-S and Cu29S16-ZnS-GeS2 pseudoternary phase diagrams for Cu2ZnGeS4. The results have been compared with those for Cu2SnS3, Cu2ZnSnS4, and CuInSe2 calculated with the same version of the CASTEP program code. The results indicate that Cu vacancies are easily formed in Cu2GeS3 and Cu2ZnGeS4 under the Cu-poor condition as in the cases of Cu2SnS3, Cu2ZnSnS4, and CuInSe2, suggesting that Cu2GeS3 and Cu2ZnGeS4 are also preferable p-type absorber materials for thin-film solar cells. Desirable preparation conditions of these thin films for photovoltaic application are discussed using the calculated formation energies of antisite defects.

  16. Tetrel bond of pseudohalide anions with XH3F (X = C, Si, Ge, and Sn) and its role in SN2 reaction

    Science.gov (United States)

    Liu, Mingxiu; Li, Qingzhong; Cheng, Jianbo; Li, Wenzuo; Li, Hai-Bei

    2016-12-01

    The complexes of XH3F⋯ N3-/OCN-/SCN- (X = C, Si, Ge, and Sn) have been investigated at the MP2/aug-cc-pVTZ(PP) level. The σ-hole of X atom in XH3F acts as a Lewis acid forming a tetrel bond with pseudohalide anions. Interaction energies of these complexes vary from -8 to -50 kcal/mol, mainly depending on the nature of X and pseudohalide anions. Charge transfer from N/O/S lone pair to X-F and X-H σ* orbitals results in the stabilization of these complexes, and the former orbital interaction is responsible for the large elongation of X-F bond length and the remarkable red shift of its stretch vibration. The tetrel bond in the complexes of XH3F (X = Si, Ge, and Sn) exhibits a significant degree of covalency with XH3F distorted significantly in these complexes. A breakdown of the individual forces involved attributes the stability of the interaction to mainly electrostatic energy, with a relatively large contribution from polarization. The transition state structures that connect the two minima for CH3Br⋯ N3-complexhave been localized and characterized. The energetic, geometrical, and topological parameters of the complexes were analyzed in the different stages of the SN2 reaction N3- + CH3Br → Br- + CH3N3.

  17. First look at NA52 data on PbPb interactions at 158 GeV/c per nucleon

    Science.gov (United States)

    Appelquist, G.; Baglin, C.; Beringer, J.; Borer, K.; Bohm, C.; Bussière, A.; Dittus, F.; Elsener, K.; Frei, D.; Gorodetzky, Ph.; Guillaud, J. P.; Hugentobler, E.; Klingenberg, R.; Lindén, T.; Lohmann, K. D.; Moser, U.; Pal, T.; Pretzl, K.; Schacher, J.; Selldén, B.; Stoffel, F.; Tuominiemi, J.; Zhang, Q. P.

    1995-07-01

    We have searched for strange matter particles, so-called strangelets, in PbPb interactions at plab = 157.7 GeV/ c per nucleon. The NA52 apparatus is also ideally suited to measure production yields and rapidity distributions of π±, K ±, p, overlinep, d, overlined, … near 0° production angle. Some preliminary results are shown.

  18. Fabrication of tensile-strained single-crystalline GeSn on transparent substrate by nucleation-controlled liquid-phase crystallization

    Science.gov (United States)

    Oka, Hiroshi; Amamoto, Takashi; Koyama, Masahiro; Imai, Yasuhiko; Kimura, Shigeru; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

    2017-01-01

    We developed a method of forming single-crystalline germanium-tin (GeSn) alloy on transparent substrates that is based on liquid-phase crystallization. By controlling and designing nucleation during the melting growth process, a highly tensile-strained single-crystalline GeSn layer was grown on a quartz substrate without using any crystal-seeds or catalysts. The peak field-effect hole mobility of 423 cm2/V s was obtained for a top-gate single-crystalline GeSn MOSFET on a quartz substrate with a Sn content of 2.6%, indicating excellent crystal quality and mobility enhancement due to Sn incorporation and tensile strain.

  19. Preparation and evaluation of SnO2-based 68Ge/68Ga generator made from 68Ge produced through (nat)Zn(α,xn) reaction.

    Science.gov (United States)

    Das, Sujata Saha; Chattopadhyay, Sankha; Alam, Md Nayer; Madhusmita; Barua, Luna; Das, Malay Kanti

    2013-09-01

    (68)Ge was produced by (nat)Zn(α,xn)(68)Ge reaction and its production yield was 31.82 kBq/μAh (0.86 μCi/μAh) at the end of irradiation (EOI). A simple chromatographic method using a SnO2 column was employed to separate (68)Ge from the target material and the co-produced non-isotopic radioisotope impurities. (68)Ge retained in the column served as the (68)Ge/(68)Ga generator. Elution efficiency of the column was about 60%. First 2 ml of the eluate contained more than 95% of the elutable activity. Post-elution purification cum concentration was done with a small cation exchange resin column. The presence of the inactive tin ions in the (68)Ga eluate was determined by the ICP-OES technique and was found to be about 0.03 ppm. Radiochemical purity of the final (68)Ga preparation was more than 99.99% and it was found to be suitable for making complex with ethylenediamine-N,N,N',N'-tetrakis(methylene phosphonic acid) (EDTMP). Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Monoanionic Tin Oligomers Featuring Sn–Sn or Sn–Pb Bonds: Synthesis and Characterization of a Tris(TriheteroarylstannylStannate and -Plumbate

    Directory of Open Access Journals (Sweden)

    Kornelia Zeckert

    2016-06-01

    Full Text Available The reaction of the lithium tris(2-pyridylstannate [LiSn(2-py6OtBu3] (py6OtBu = C5H3N-6-OtBu, 1, with the element(II amides E{N(SiMe32}2 (E = Sn, Pb afforded complexes [LiE{Sn(2-py6OtBu3}3] for E = Sn (2 and E = Pb (3, which reveal three Sn–E bonds each. Compounds 2 and 3 have been characterized by solution NMR spectroscopy and X-ray crystallographic studies. Large 1J(119Sn–119/117Sn as well as 1J(207Pb–119/117Sn coupling constants confirm their structural integrity in solution. However, contrary to 2, complex 3 slowly disintegrates in solution to give elemental lead and the hexaheteroarylditin [Sn(2-py6OtBu3]2 (4.

  1. Lambda Produktion in Pb-Au Kollisionen bei 40-A-GeV

    CERN Document Server

    Schmitz, Wolfgang

    2001-01-01

    The CERES-experiment at the CERN-SPS investigates the production of electron-positron pairs in ultrarelativistic nuclear collisions. The CERES spectrometer was upgraded during 1998 by the addition of a Time Projection Chamber (TPC) with a radial electric drift field and two coils of a warm magnet to provide a momentum analysis. This thesis deals with the design and construction of the CERES TPC and a first $Lambda$-analysis in 40 A,GeV Pb+Au collisions. The relative momentum resolution $sigma (dp/p)^2$ = $0.027^2+(0.024 ~ p)^2$ (in GeV/c) was determined using the measured width of the $Lambda$ invariant mass spectrum ($sigma$ = 12 MeV/c$^2$) and comparing it to a TPC simulation containing all measured distortions of a trajectory. The resolution is about a factor of 2.5 worse compared to its design value due to the still incomplete calibration. Analysing the fully corrected $Lambda$ transverse momentum spectra in a rapidity interval 2.0 $<$ $y_{m {Lambda}}$ $<$ 2.4 close to midrapidity for centralities $...

  2. Microstructural Evolution and Migration Mechanism Study in a Eutectic Sn-37Pb Lap Joint Under High Current Density

    Science.gov (United States)

    Zhang, Zhihao; Cao, Huijun; Yang, Haifeng; Xiao, Yong; Li, Mingyu; Yu, Yuxi; Yao, Shun

    2017-08-01

    The microstructural evolution in eutectic Sn-37Pb solder under high current density seriously threatens the reliability of solder interconnections, but atomic electromigration has often been confused with thermomigration. In this paper, after decoupling the effect of the non-uniform temperature distribution in a Cu/Sn-37Pb/Cu lap joint from the current stress, the microstructural evolution was investigated under an average current density of 1.84 × 104 A cm-2 for 0-24 h. The decomposition and recombination of the Pb-rich phase occurred at the cathode and the anode, respectively. The corresponding migration mechanism was proposed from the viewpoint of energy and was explained by the interactions among the potential energies of ripening, electron wind force, and back stress. Our study may be helpful for understanding the migration mechanism and reliability of eutectic two-phase solder joints and provides supporting data for interpreting the acceleration tests of Sn-37Pb solder joints under electromigration.

  3. Silver(i)-promoted insertion into X-H (X = Si, Sn, and Ge) bonds with N-nosylhydrazones.

    Science.gov (United States)

    Liu, Zhaohong; Li, Qiangqiang; Yang, Yang; Bi, Xihe

    2017-02-21

    Silver(i)-promoted carbene insertion into X-H (X = Si, Sn, and Ge) bonds has been realized by using unstable diazo compounds, which are generated in situ from N-nosylhydrazones as carbene precursors. The reaction tolerates a wide range of functional groups and delivers a number of valuable silicon-containing compounds in very high yields (up to 96%). Moreover, organostannanes and organogermanes were as well effectively obtained in very good yields under optimal conditions.

  4. Electronic structure and magnetism of Ge(Sn)TMXTe1-X (TM = V, Cr, Mn): A first principles study

    Science.gov (United States)

    Liu, Yong; Bose, S. K.; Kudrnovský, J.

    2016-12-01

    This work presents the results of first principles calculations of the electronic and magnetic properties of the compound SnTe and GeTe in zinc blende (ZB) and rock salt (RS) structures, doped with 3d transition metal V, Cr, and Mn. The present study, initiated from the viewpoint of potential application in spintronics, is motivated by our earlier work involving these two compounds, where the doping was limited to the Sn and Ge sublattices. In view of some discrepancies between our calculated results and the available experimental data, in this work we have examined the effect of the Te-sublattice doping. The case of Mn-doping, where the previous results of calculations seemed to differ most from the experimentally available data, is examined further by looking at the effect of Mn atoms partially occupying interstitial sites as well. From the standpoint of potential application in spintronics, we look for half-metallic (HM) states and tabulate their properties in both rock salt and zinc blende structures. ZB structure is found to be more conducive to HM state in general. Among the binary compounds we identify several HM candidates: VGe, VSn, MnGe, MnSn and MnTe at their equilibrium volumes and all in ZB structure. Estimates of the Curie temperature for the ferromagnetic compounds including the half-metals are presented. It is shown that despite the ferromagnetic (FM) nature of the Mn-Mn interaction for the Te-doped case, a simultaneous doping of both Ge(Sn)- and Te-sublattice with Mn atoms would leave the material predominantly antiferromagnetic (AFM).

  5. Transverse momentum distribution of J/psi produced in Pb-Pb interactions at 158 GeV/c per nucleon

    CERN Document Server

    Abreu, M C; Alessandro, B; Astruc, J; Arnaldi, R; Atayan, M; Baglin, C; Baldit, A; Bellaiche, F G; Bedjidian, Marc; Beolè, S; Boldea, V; Bordalo, P; Bussière, A; Capony, V; Castor, J I; Casagrande, L; Chambon, T; Chaurand, B; Chevrot, I; Cheynis, B; Chiavassa, E; Cicalò, C; Constantinescu, S; Comets, M P; Cruz, J; De Falco, A; Dellacasa, G; De Marco, N; Devaux, A; Dita, S; Drapier, O; Espagnon, B; Fargeix, J; Filippov, S N; Fleuret, F; Force, P; Gallio, M; Gavrilov, Yu K; Gerschel, C; Giubellino, P; Golubeva, M B; Gonin, M; Grigorian, A A; Grossiord, J Y; Guber, F F; Guichard, A; Gulkanian, H R; Hakobyan, R S; Haroutunian, R; Idzik, M; Jouan, D; Karavitcheva, T L; Kluberg, L; Kurepin, A B; Le Bornec, Y; Lourenço, C; Macciotta, P; McCormick, M; Ohlsson-Malek, F; Marzari-Chiesa, A; Masera, M; Masoni, A; Mehrabyan, S S; Mourgues, S; Musso, A; Petiau, P; Silva, W L P; Piccotti, A; Pizzi, J R; Puddu, G; Quintans, C; Racca, C; Ramello, L; Ramos, S; Rato-Mendes, P; Riccati, L; Romana, A; Sartori, S M; Saturnini, P; Scomparin, E; Shahoyan, R; Silva, S; Soave, C; Serci, S; Sonderegger, P; Tarrago, X; Temnikov, P; Topilskaya, N S; Usai, G L; Vale, C; Vercellin, Ermanno; Willis, N

    1999-01-01

    The production of dimuon in Pb-Pb collisions at 158 GeV/c per nucleon has been measured at the CERN SPS in experiment NA50. An anomalous suppression of J/psi production cross section has been observed in comparison with the value expected from the results obtained in proton and light ion induced reactions. An analysis of the transverse momentum distribution of J/psi is presented. For J/psi production, values have been calculated as a function of centrality.

  6. Electric charge fluctuations in central Pb+Pb collisions at 20A, 30A, 40A, 80A, and 158A GeV

    CERN Document Server

    Alt, C; Baatar, B; Barna, D; Bartke, Jerzy; Behler, M; Betev, L; Bialkowska, H; Billmeier, A; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Brun, R; Buncic, P; Cerny, V; Christakoglou, P; Chvala, O; Cramer, J G; Csató, P; Darmenov, N; Dimitrov, A; Dinkelaker, P; Eckardt, V; Filip, P; Flierl, D; Fodor, Z; Foka, P; Freund, P; Friese, V; Gál, J; Gazdzicki, M; Georgopoulos, G; Gladysz-Dziadus, E; Grebieszkow, K; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kliemant, M; Kniege, S; Kolesnikov, V I; Kollegger, T; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Lévai, Peter; Litov, L; Lungwitz, B; Makariev, M; Malakhov, A I; Markert, C; Mateev, M; Mayes, B W; Melkumov, G L; Meurer, C; Mischke, A; Mitrovski, M; Molnár, J; Mrówczynski, S; Pálla, G; Panagiotou, A D; Panayotov, D; Petridis, A; Pikna, M; Pinsky, L; Pühlhofer, F; Reid, J G; Renfordt, R; Richard, A; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Sann, H; Schmitz, N; Seyboth, P; Siklér, F; Sitár, B; Skrzypczak, E; Stefanek, G; Stock, R; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Trainor, T A; Varga, D; Vassiliou, Maria; Veres, G I; Vesztergombi, G; Vranic, D; Wetzler, A; Wlodarczyk, Z; Yoo, I K; Zaranek, J; Zimányi, J; Van Leeuwen, M

    2004-01-01

    Results are presented on event-by-event electric charge fluctuations in central Pb+Pb collisions at 20A, 30A, 40A, 80A, and 158A GeV. The observed fluctuations are close to those expected for a gas of pions correlated by global charge conservation only. These fluctuations are considerably larger than those calculated for an ideal gas of deconfined quarks and gluons. The present measurements do not necessarily exclude reduced fluctuations from a quark-gluon plasma because these might be masked by contributions from resonance decays.

  7. Bose-Einstein correlations of charged kaons in central Pb + Pb collisions at $E_{beam}$ = 158 GeV per nucleon

    CERN Document Server

    Afanasiev, S V; Baatar, B; Barna, D; Bartke, Jerzy; Barton, R A; Behler, M; Betev, L; Bialkowska, H; Billmeier, A; Blume, C; Blyth, C O; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Brun, R; Buncic, P; Cerny, V; Chvala, O; Cramer, J G; Csató, P; Dinkelaker, P; Eckardt, V; Filip, P; Fodor, Z; Foka, P Y; Freund, P; Friese, V; Gál, J; Gazdzicki, M; Georgopoulos, G; Gladysz-Dziadus, E; Hegyi, S; Höhne, C; Igo, G; Jones, P G; Kadija, K; Karev, A; Kolesnikov, V I; Kollegger, T; Kowalski, M; Kraus, I; Kreps, M; Van Leeuwen, M; Lednicky, R; Lévai, Peter; Malakhov, A I; Margetis, S; Markert, C; Mayes, B W; Melkumov, G L; Meurer, C; Mischke, A; Mitrovski, M; Molnár, J; Nelson, J M; Pálla, G; Panagiotou, A D; Perl, K; Petridis, A; Pikna, M; Pinsky, L; Pühlhofer, F; Reid, J G; Renfordt, R E; Retyk, W; Roland, C; Roland, G; Rybicki, A; Sammer, T; Sandoval, A; Sann, H; Schmitz, N; Seyboth, P; Siklér, F; Sitár, B; Skrzypczak, E; Squier, G T A; Stock, R; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Trainor, T A; Varga, D; Vassiliou, Maria; Veres, G I; Vesztergombi, G; Vranic, D; Wetzler, A; Whitten, C; Yoo, I K; Zaranek, J; Zimányi, J; 10.1016/S0370-2693(03)00102-3

    2003-01-01

    Bose-Einstein correlations of charged kaons were measured near mid- rapidity in central Pb + Pb collisions at 158 A GeV by the NA49 experiment at the CERN SPS. Source radii were extracted using the Yano-Koonin-Podgoretsky and Bertsch-Pratt parameterizations. The results are compared to published pion and kaon data. The measured m /sub perpendicular to / dependence for kaons and pions is consistent with collective transverse expansion of the source and a freeze-out time of about 9.5 fm. (31 refs).

  8. First look at NA52 data on Pb-Pb interactions at 158 A {center_dot} GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Appelquist, G. [Department of Physics, University of Stockholm (Sweden); Baglin, C. [CNRS-IN2PS, LAPP Annecy (France); Beringer, J.; Borer, K. [Lab. for High Energy Physics, University of Bern (Switzerland); Bohm, C. [Department of Physics, University of Stockholm (Sweden); Bussiere, A. [CNRS-IN2PS, LAPP Annecy (France); Dittus, F. [Lab. for High Energy Physics, University of Bern (Switzerland); Elsener, K. [CERN, Geneva (Switzerland); Frei, D. [Lab. for High Energy Physics, University of Bern (Switzerland); Gorodetzky, P. [CNRS-IN2PS, CRN Strasbourg (France); Guillaud, J.P. [CNRS-IN2PS, LAPP Annecy (France); Hugentobler, E.; Klingenberg, R. [Lab. for High Energy Physics, University of Bern (Switzerland); Linden, T. [Department of Physics, University of Helsinki (Finland); Lohmann, K.D. [CERN, Geneva (Switzerland); Moser, U.; Pal, T.; Pretzl, K.; Schacher, J. [Lab. for High Energy Physics, University of Bern (Switzerland); Sellden, B. [Department of Physics, University of Stockholm (Sweden); Stoffel, F. [Lab. for High Energy Physics, University of Bern (Switzerland); Tuominiemi, J. [Department of Physics, University of Helsinki (Finland); Zhang, Q.P. [Department of Physics, University of Stockholm (Sweden); Presented by F. Dittus for the Newmass Collaboration

    1995-07-20

    We have searched for strange matter particles, so-called {ital strangelets}, in Pb-Pb interactions at {ital p}{sub lab}=157.7 GeV/{ital c} per nucleon. The NA52 apparatus is also ideally suited to measure production yields and rapidity distribution of {pi}{sup {plus_minus}}, K{sup {plus_minus}}, p, {bar p}, d, {bar d}, ... near 0{sup 0} production angle. Some preliminary results are shown. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}.

  9. Half-metallicity and magnetism of quaternary Heusler compounds CoRuTiZ (Z=Si, Ge, and Sn)

    Science.gov (United States)

    Bahramian, S.; Ahmadian, F.

    2017-02-01

    First-principle calculations based on the density functional theory for new quaternary Heusler compounds CoRuTiZ (Z=Si, Ge, and Sn) were performed. It was found that all three compounds were stable at YI structure in ferromagnetic state. The CoRuTiSi, CoRuTiGe, and CoRuTiSn were half-metal with integer magnetic moments of 1.00 μB per formula unit and half-metallic gaps of 0.13, 0.10, and 0.01 eV at their equilibrium volume, respectively. The density of states (DOSs) and band structures of these compounds were studied and the origin of half-metallicity was discussed. The CoRuTiSi, CoRuTiGe, and CoRuTiSn compounds showed half-metallic characteristics at lattice constants ranges of 5.77-6.36 Å, 5.66-6.16 Å, and 5.83-6.23 Å, indicating the lattice distortion did not affect the half-metallic properties of these compounds which makes them interesting materials in the spintronic field.

  10. Super-Resolution Near-Field Disk with Phase-Change Sn-Doped GeSbTe Mask Layer

    Science.gov (United States)

    Lee, Mei Ling; Thong Yong, Kok; Lip Gan, Chee; Hou Ting, Lee; Shi, Lu Ping

    2009-03-01

    A new mask layer of Sn-doped (7 at. %) Ge2Sb2Te5 was developed and used on super-resolution near-field phase-change optical disks (super-RENS). Temperature-dependent reflectivity result showed a reflectivity change at 169 °C with Sn doping into Ge2Sb2Te5. The mask material also showed high thermal stability. Optical study indicated the suitability of the film for use in blue-laser recording and as a mask layer. Fast crystallization within 90 ns was achieved using a pulsed high-power laser beam of 405 nm wavelength. Dynamic recording performance of the new structure showed carrier-to-noise ratios (CNR) of 37 and 18 dB obtained for 80 and 50 nm mark sizes, respectively. Readout thermal stability of 12,000 cycles was realized for 80 nm mark sizes. The incorporation of Sn-doped GeSbTe (GST) as mask layer in the super-RENS structure significantly improved the CNR and thermal stability of the disk.

  11. Suppression of high-p(T) neutral pion production in central Pb+Pb collisions at root s(NN)=17.3 GeV relative to p+C and p+Pb collisions

    NARCIS (Netherlands)

    Aggarwal, M. M.; Ahammed, Z.; Angelis, A. L. S.; Antonenko, V.; Arefiev, V.; Astakhov, V.; Avdeitchikov, V.; Awes, T. C.; Baba, P. V. K. S.; Badyal, S. K.; Bathe, S.; Batiounia, B.; Baumann, C.; Bernier, T.; Bhalla, K. B.; Bhatia, V. S.; Blume, C.; Bucher, D.; Buesching, H.; Carlen, L.; Chattopadhyay, S.; Decowski, M. P.; Delagrange, H.; Donni, P.; Majumdar, M. R. Dutta; El Chenawi, K.; Dubey, A. K.; Enosawa, K.; Fokin, S.; Frolov, V.; Ganti, M. S.; Garpman, S.; Gavrishchuk, O.; Geurts, F. J. M.; Ghosh, T. K.; Glasow, R.; Guskov, B.; Gustafsson, H.A.; Gutbrod, H. H.; Hrivnacova, I.; Ippolitov, M.; Kalechofsky, H.; Kamermans, R.; Karadjev, K.; Karpio, K.; Kolb, B. W.; Kosarev, I.; Koutcheryaev, I.; Kugler, A.; Kulinich, P.; Kurata, M.; Lebedev, A.; Loehner, H.; Luquin, L.; Mahapatra, D. P.; Manko, V.; Martin, M.; Martinez, G.; Maximov, A.; Miake, Y.; Mishra, G. C.; Mohanty, B.; Mora, M. -J.; Morrison, D.; Mukhanova, T.; Mukhopadhyay, D. S.; Naef, H.; Nandi, B. K.; Nayak, S. K.; Nayak, T. K.; Nianine, A.; Nikitine, V.; Nikolaev, S.; Nilsson, P.; Nishimura, S.; Nomokonov, P.; Nystrand, J.; Oskarsson, A.; Otterlund, I.; Pavliouk, S.; Peitzmann, T.; Peressounko, D.; Petracek, V.; Phatak, S. C.; Pinganaud, W.; Plasil, F.; Purschke, M. L.; Rak, J.; Rammler, M.; Raniwala, R.; Raniwala, S.; Rao, N. K.; Retiere, F.; Reygers, K.; Roland, G.; Rosselet, L.; Roufanov, I.; Roy, C.; Rubio, J. M.; Sambyal, S. S.; Santo, R.; Sato, S.; Schlagheck, H.; Schmidt, H. -R.; Schutz, Y.; Shabratova, G.; Shah, T. H.; Sibiriak, I.; Siemiarczuk, T.; Silvermyr, D.; Sinha, B. C.; Slavine, N.; Soederstroem, K.; Sood, G.; Sorensen, S. P.; Stankus, P.; Stefanek, G.; Steinberg, P.; Stenlund, E.; Sumbera, M.; Svensson, T.; Tsvetkov, Artem; Tykarski, L.; Von der Pijll, E. C.; Eijndhoven, N. V.; Nieuwenhuizen, G. J. V.; Vinogradov, A.; Viyogi, Y. P.; Vodopianov, A.; Voeroes, S.; Wyslouch, B.; Young, G. R.

    2008-01-01

    Neutral pion transverse momentum spectra were measured in p+C and p+Pb collisions at root s(NN) = 17.4 GeV at midrapidity (2.3 less than or similar to eta(lab)less than or similar to 3.0) over the range 0.7 less than or similar to p(T)less than or similar to 3.5 GeV/c. The spectra are compared to

  12. GeSn Alloy Growth Using Ion Implantation and Rapid Thermal Anneal%基于离子注入与快速热退火的GeSn合金生长技术

    Institute of Scientific and Technical Information of China (English)

    周谦; 杨谟华; 王向展; 李竞春; 罗谦

    2013-01-01

    针对源漏诱生应变Ge沟道p-MOSFET的发展趋势,开发了一种基于离子注入与快速热退火的GeSn合金生长新技术,并进行了二次离子质谱、X射线衍射、透射电子显微镜和方块电阻等测试.结果表明,采用快速热退火,可将单晶Ge衬底中的Sn原子激发至替位式位置,形成GeSn合金.当退火温度为400℃时,Sn原子激活率为100%,其峰值浓度固定为1×1021 cm-3,与Sn的初始注入剂量无关.该技术与现有CMOS工艺兼容,附加成本低,适用于单轴压应变Ge沟道MOSFET的大规模生产.%A new technique for GeSn alloy growth was demonstrated In this technique, high Sn dose ion implantation was used to incorporate Sn atoms in Ge substrate, and rapid thermal anneal (RTA) was employed for solid phase epitaxy of GeSn alloy. SIMS, XRD, TEM and four-point probe measurements were carried out to inspect material and electrical properties of the as-annealed sample. Experimental results showed that RTA could activate Sn atoms in single crystal Ge and form GeSn alloy. Sn activation rate reached 100% when RTA temperature was 400 ℃. The substitutional Sn concentration was fixed to 1×1021 cm-3 and it was not related to initial Sn dose. The new technique for GeSn growth, which was fully compatible with standard CMOS technology with minimal additional cost, is a prospective way for mass production of uniaxial strained Ge MOSFET with GeSn source/drain stressors.

  13. Enhanced photoelectrochemical performance of PbS sensitized Sb–SnO{sub 2}/TiO{sub 2} nanotube arrays electrode under visible light illumination

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jia; Tang, Chengli [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Xu, Hao, E-mail: xuhao@mail.xjtu.edu.cn [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Yan, Wei, E-mail: yanwei@mail.xjtu.edu.cn [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China)

    2015-06-05

    Highlights: • Sb–SnO{sub 2} is used to modify TiO{sub 2} NTAs by microwave method. • PbS is employed to sensitive Sb–SnO{sub 2}/TiO{sub 2} NTAs by S-SILAR method. • Sb–SnO{sub 2} improves electrons transfer and PbS enhances visible light absorption. • The composite electrode shows enhanced photoelectrochemical properties. • The composite electrode exhibits high hydrogen evolution and high QE. - Abstract: The novel PbS sensitized Sb–SnO{sub 2}/TiO{sub 2} nanotube arrays (NTAs) composite electrode (PbS/Sb–SnO{sub 2}/TiO{sub 2} NTAs) was fabricated by microwave combined with sonication-assisted successive ionic layer adsorption and reaction technique (S-SILAR). The obtained electrodes were characterized by field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–Vis diffuse reflectance absorption spectra techniques. Enhanced photocurrent (15.52 mA/cm{sup 2}) of the PbS/Sb–SnO{sub 2}/TiO{sub 2} NTAs electrode was observed and can be attributed to the facile photo-generated electrons transfer and enhanced charge separation efficiency. Furthermore, the PbS/Sb–SnO{sub 2}/TiO{sub 2} NTAs composite electrode shows a higher H{sub 2} production rate than the Sb–SnO{sub 2}/TiO{sub 2} NTAs electrode and PbS/TiO{sub 2} NTAs electrode. The results indicate that the PbS/Sb–SnO{sub 2}/TiO{sub 2} NTAs electrode is a promising photoanode in visible photocatalytic water splitting.

  14. Proton-Lambda correlations in central Pb plus Pb collisions at root s(NN)=17.3 GeV

    CERN Document Server

    Botje, M; Karev, A; Chvala, O; Roland, G; Skrzypczak, E; Kowalski, M; Panagiotou, A D; Malakhov, A I; Prindle, D; Sikler, F; Bartke, J; Strobele, H; Vranic, D; Cetner, T; Vesztergombi, G; Makariev, M; Laszlo, A; Schmitz, N; Grebieszkow, K; Rybczynski, M; Wojtaszek-Szwarc, A; Szuba, M; Beck, H; Palla, G; Bogusz, M; Peryt, W; Kresan, D; Eckardt, V; Lacey, R; Betev, L; Kolesnikov, V I; Susa, T; Gazdzicki, M; Sandoval, A; Friese, V; Mateev, M; Foka, P; Mitrovski, M; Utvic, M; Mrowczynski, S; Boimska, B; Christakoglou, P; Stock, R; Seyboth, P; Blume, C; Bialkowska, H; Rybicki, A; Barna, D; Buncic, P; Schuster, T; Vassiliou, M; Wlodarczyk, Z; Stefanek, G; Book, J; Renfordt, R; Veres, G I; Nicolic, V; Varga, D; Pluta, J; Anticic, T; Melkumov, G L; Mackowiak, M; Hohne, C; Fodor, Z; Cramer, J G; Baatar, B; Puhlhofer, F; Chung, P; Kadija, K; van Leeuwen, M

    2011-01-01

    The momentum correlation between protons and Lambda particles emitted from central Pb+Pb collisions at root s(NN) = 17.3 GeV was studied by the NA49 experiment at the CERN Super Proton Synchrotron. A clear enhancement is observed for small relative momenta (q(inv) < 0.2 GeV). By fitting a theoretical model, which uses the strong interaction between the proton and the Lambda in a given pair, to the measured data, a value for the effective source size is deduced. Assuming a static Gaussian source distribution, we derive an effective radius parameter of R(G) = 3.02 +/- 0.20(stat.)(-0.16)(+0.44)(syst.) fm.

  15. 158A GeV/c Pb-Pb碰撞中的QGP相变问题研究%Study on QGP phase transition in Pb-Pb collisions at 158A GeV/c

    Institute of Scientific and Technical Information of China (English)

    李强; 姜志进; 夏宏福

    2006-01-01

    以J/ψ反常抑制现象为夸克-胶子等离子体(QGP)相变信号,在核与随动者吸收理论的基础上,导出了有相变产生时高能重离子碰撞中的J/ψ微分产生截面,并对NA50合作组给出的入射动量为158A GeV/c的Pb-Pb碰撞中的实验数据进行了分析,较好地解释了实验结果.表明在NA50合作组的实验中,QGP物质已经产生.

  16. Creep Behavior of a Sn-Ag-Bi Pb-Free Solder

    Directory of Open Access Journals (Sweden)

    Alice Kilgo

    2012-11-01

    Full Text Available Compression creep tests were performed on the ternary 91.84Sn-3.33Ag-4.83Bi (wt.%, abbreviated Sn-Ag-Bi Pb-free alloy. The test temperatures were: −25 °C, 25 °C, 75 °C, 125 °C, and 160 °C (± 0.5 °C. Four loads were used at the two lowest temperatures and five at the higher temperatures. The specimens were tested in the as-fabricated condition or after having been subjected to one of two air aging conditions: 24 hours at either 125 °C or 150 °C. The strain-time curves exhibited frequent occurrences of negative creep and small-scale fluctuations, particularly at the slower strain rates, that were indicative of dynamic recrystallization (DRX activity. The source of tertiary creep behavior at faster strain rates was likely to also be DRX rather than a damage accumulation mechanism. Overall, the strain-time curves did not display a consistent trend that could be directly attributed to the aging condition. The sinh law equation satisfactorily represented the minimum strain rate as a function of stress and temperature so as to investigate the deformation rate kinetics: dε/dtmin = Asinhn (ασ exp (−ΔH/RT. The values of α, n, and  ΔH were in the following ranges (±95% confidence interval: α, 0.010–0.015 (±0.005 1/MPa; n, 2.2–3.1 (±0.5; and ΔH, 54–66 (±8 kJ/mol. The rate kinetics analysis indicated that short-circuit diffusion was a contributing mechanism to dislocation motion during creep. The rate kinetics analysis also determined that a minimum creep rate trend could not be developed between the as-fabricated versus aged conditions. This study showed that the elevated temperature aging treatments introduced multiple changes to the Sn-Ag-Bi microstructure that did not result in a simple loss (“softening” of its mechanical strength.

  17. Nanoscale semiconductor Pb{sub 1-x}Sn{sub x}Se (x = 0.2) thin films synthesized by electrochemical atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lin Shaoxiong; Zhang Xin; Shi Xuezhao; Wei Jinping; Lu Daban; Zhang Yuzhen; Kou Huanhuan [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Wang Chunming, E-mail: wangcm@lzu.edu.cn [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China)

    2011-04-15

    In this paper the fabrication and characterization of IV-VI semiconductor Pb{sub 1-x}Sn{sub x}Se (x = 0.2) thin films on gold substrate by electrochemical atomic layer deposition (EC-ALD) method at room temperature are reported. Cyclic voltammetry (CV) is used to determine approximate deposition potentials for each element. The amperometric I-t technique is used to fabricate the semiconductor alloy. The elements are deposited in the following sequence: (Se/Pb/Se/Pb/Se/Pb/Se/Pb/Se/Sn ...), each period is formed using four ALD cycles of PbSe followed by one cycle of SnSe. Then the deposition manner above is cyclic repeated till a satisfactory film with expected thickness of Pb{sub 1-x}Sn{sub x}Se is obtained. The morphology of the deposit is observed by field emission scanning electron microscopy (FE-SEM). X-ray diffraction (XRD) pattern is used to study its crystalline structure; X-ray photoelectron spectroscopy (XPS) of the deposit indicates an approximate ratio 1.0:0.8:0.2 of Se, Pb and Sn, as the expected stoichiometry for the deposit. Open-circuit potential (OCP) studies indicate a good p-type property, and the good optical activity makes it suitable for fabricating a photoelectric switch.

  18. Superconductivity induced by In substitution into the topological crystalline insulator Pb0.5Sn0.5Te

    Science.gov (United States)

    Zhong, R. D.; Schneeloch, J. A.; Liu, T. S.; Camino, F. E.; Tranquada, J. M.; Gu, G. D.

    2014-07-01

    Indium substitution turns the topological crystalline insulator (TCI) Pb0.5Sn0.5Te into a possible topological superconductor. To investigate the effect of the indium concentration on the crystal structure and superconducting properties of (Pb0.5Sn0.5)1-xInxTe, we have grown high-quality single crystals using a modified floating-zone method and have performed systematic studies for indium content in the range 0≤x≤0.35. We find that the single crystals retain the rocksalt structure up to the solubility limit of indium (x ˜0.30). Experimental dependencies of the superconducting transition temperature (Tc) and the upper critical magnetic field (Hc2) on the indium content x have been measured. The maximum Tc is determined to be 4.7 K at x =0.30, with μ0Hc2(T =0)≈5 T.

  19. Synthesis of PbTe-SnTe particles by thermal decomposition of salts to create nano-structured thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Leontyev, V.G.; Ivanova, L.D. [Institution of Russian Academy of Sciences A.A. Baikov Institute of Metallurgy and Material Science RAS, Leninskii prospect, 49, 119991 Moscow (Russian Federation); Bente, K. [Institut fuer Mineralogie, Kristallographie und Materialwissenschaft, Leipzig University, Scharnhorststr. 20, 04275 Leipzig (Germany); Gremenok, V.F. [State Scientific and Production Association ' ' Scientific-Practical Materials Research Centre of the National Academy of Sciences of Belarus' ' , P. Brovka str. 19, 220072 Minsk (Belarus)

    2012-05-15

    Micro- and nanocrystalline particles of Pb-Sn-Te mixed crystals were synthesized using thermal decomposition and chemical interaction of lead acetate, tin oxalate and tellurium powder mixture in H{sub 2} atmosphere. For the process parameter optimization data of thermal gravimetry (TG), X-ray diffraction (XRD), electronic microscopy (TEM, SEM) and measurements of the specific surface of particles were used. Additionally the influence of gas phases on the decomposition kinetics, crystal structure, size, specific surface of the particles, gains composition and the physical properties were analyzed. Seebeck coefficient values increased and conductivity decreased with decreasing tin concentration. The presented method for preparing PbTe-SnTe polydisperse particles is developed to create nano-structured thermoelectric materials with high figure of merit. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. The influence of melt convection on dendritic spacing of downward unsteady-state directionally solidified Sn-Pb alloys

    Directory of Open Access Journals (Sweden)

    José Eduardo Spinelli

    2006-03-01

    Full Text Available Microstructures are the strategic link between materials processing and materials behavior. A dendritic structure is the most frequently observed pattern of solidified alloys. The microstructural scales of dendrites, such as primary and secondary arm spacings, control the segregation profiles and the formation of secondary phases within interdendritic regions, determine the properties of cast structures. In this work, the influence of thermosolutal convection on dendrite arm spacings is experimentally examined in the downward vertical unsteady-state directional solidification of Sn-Pb hypoeutectic alloys. The experimental observations are compared not only with the main predictive theoretical models for dendritic spacings but also with experimental results obtained for Sn-Pb alloys solidified vertically upwards. Primary dendritic arm spacings have been affected by the direction of growth, decreasing in conditions of downward vertical solidification when compared with those grown vertically upwards. Further, the unsteady-state lambda1 predictive models did not generate the experimental observations.

  1. The effect of hydrostatic pressure and uniaxial strain on the electronic structure of Pb$_{\\text{1-x}}$Sn$_{\\text{x}}$Te

    CERN Document Server

    Geilhufe, Matthias; Thomas, Stefan; Däne, Markus; Tripathi, Gouri S; Entel, Peter; Hergert, Wolfram; Ernst, Arthur

    2015-01-01

    The electronic structure of Pb$_{1-x}$Sn$_{x}$Te is studied by using the relativistic Korringa-Kohn-Rostoker Green function method in the framework of density functional theory. For all concentrations $x$, Pb$_{1-x}$Sn$_{x}$Te is a direct semiconductor with a narrow band gap. In contrast to pure lead telluride, tin telluride shows an inverted band characteristic close to the Fermi energy. It will be shown that this particular property can be tuned, first, by alloying PbTe and SnTe and, second, by applying hydrostatic pressure or uniaxial strain. Furthermore, the magnitude of strain needed to switch between the regular and inverted band gap can be tuned by the alloy composition. Thus, there is range of potential usage of Pb$_{1-x}$Sn$_{x}$Te for spintronic applications.

  2. STUDY ON TECTONIC FEATURE AND METALLOGENIC MECHANISM OF THE PENGSHAN Sn-Pb-Zn POLYMETALLIC OREFIELD,JIANGXI PROVINCE

    Institute of Scientific and Technical Information of China (English)

    LU Shudong; DU Yangsong; XIAO E; XU Chunwei

    2005-01-01

    The Pengshan Sn-Pb-Zn polymetallic orefield is located in the Jiujiang-Ruichang region, which is a segment of the middle-lower Yangtze River metallogenic belt. The Pengshan late Yanshanian buried pluton with granitic composition is a calc-alkaline pluton, intrusion of which is responsible for the formation of the Sn-Pb-Zn polymetallic deposit through providing thermodynamic condition and ore-forming material.The long-active basement rifts initially formed in the Jinning period and the domal structure with induced secondary order faults formed by emplacement of the pluton, such as ring-detachment fault,top-detachment fault and joint fissure, act as the passage-way for magma and ore-forming fluid and impounding structure for ore deposit. The magma to form the pluton with DI>90 is intensively differentiated. The variation of the ore-forming fluid in composition with falling in temperature caused by action of magmatic hydrothermal convection system combined with groundwater convection system attributes to mineralization of various types in the orefield. The mineralization process can be divided into six stages, i.e., greisenization, skarnization of early stage, fluorite-stanniferous silication stage, skarnization of advanced stage, quartz and cassiterite-sulfuration stage and carbonation stage. The mineral assemblages formed in different mineralization stages are different owing to temperature changing and may be overlapped in space. Malayaite is recognized from the mineral assemblage formed in the fluorite-stanniferous silication stage. The ores in the Pengshan Sn-Pb-Zn polymetallic deposit are spatially zoned with variation from As-Sn mineral assemblage of high temperature in the inner zone through Sn-Pb and Pb-Zn-Ag mineral assemblage of middle temperature in the middle zone to fluorite mineral assemblage of low temperature in the outer zone.The exchanging of Sn,Mg and Fe between biotite and hydrothermal fluid resulted from variation of physicochemical condition

  3. Impact of 5% NaCl Salt Spray Pretreatment on the Long-Term Reliability of Wafer-Level Packages with Sn-Pb and Sn-Ag-Cu Solder Interconnects

    Science.gov (United States)

    Liu, Bo; Lee, Tae-Kyu; Liu, Kuo-Chuan

    2011-10-01

    Understanding the sensitivity of Pb-free solder joint reliability to various environmental conditions, such as corrosive gases, low temperatures, and high-humidity environments, is a critical topic in the deployment of Pb-free products in various markets and applications. The work reported herein concerns the impact of a marine environment on Sn-Pb and Sn-Ag-Cu interconnects. Both Sn-Pb and Sn-Ag-Cu solder alloy wafer-level packages, with and without pretreatment by 5% NaCl salt spray, were thermally cycled to failure. The salt spray test did not reduce the characteristic lifetime of the Sn-Pb solder joints, but it did reduce the lifetime of the Sn-Ag-Cu solder joints by over 43%. Although both materials showed strong resistance to corrosion, the localized nature of the corroded area at critical locations in the solder joint caused significant degradation in the Sn-Ag-Cu solder joints. The mechanisms leading to these results as well as the extent, microstructural evolution, and dependency of the solder alloy degradation are discussed.

  4. Highly effective strain-induced band-engineering of (111) oriented, direct-gap GeSn crystallized on amorphous SiO2 layers

    Science.gov (United States)

    Li, Haofeng; Wang, Xiaoxin; Liu, Jifeng

    2016-03-01

    We demonstrate highly effective strain-induced band-engineering of (111) oriented direct-gap Ge1-xSnx thin films (0.074 GeSn films also demonstrate high thermal stability, offering both excellent direct-gap optoelectronic properties and fabrication/operation robustness for integrated photonics.

  5. Latest results from NA50 on $J/\\psi$ suppression in Pb-Pb collisions at 158 GeV/c

    CERN Document Server

    Beolè, S; Alessandro, B; Alexa, C; Arnaldi, R; Ataian, M R; Baglin, C; Baldit, A; Bedjidian, Marc; Boldea, V; Bordalo, P; Borenstein, S R; Borges, G; Bussière, A; Capelli, L; Castor, J I; Castanier, C; Chaurand, B; Cheynis, B; Chiavassa, E; Cicalò, C; Claudino, T; Comets, M P; Constans, N; Constantinescu, S; Cortese, P; Cruz, J; De Marco, N; De Falco, A; Dellacasa, G; Devaux, A; Dita, S; Drapier, O; Espagnon, B; Fargeix, G; Force, P; Gallio, M; Gavrilov, Yu K; Gerschel, C; Giubellino, P; Golubeva, M B; Gonin, M; Grigorian, A A; Grigorian, S; Grossiord, J Y; Guber, F F; Guichard, A; Gulkanian, H R; Hakobyan, R S; Haroutunian, R; Idzik, M; Jouan, D; Karavitcheva, T L; Kluberg, L; Kurepin, A B; Le Bornec, Y; Lourenço, C; Macciotta, P; MacCormick, M; Marzari-Chiesa, A; Masera, M; Masoni, A; Monteno, M; Musso, A; Petiau, P; Piccotti, A; Pizzi, J R; Prado da Silva, W L; Prino, F; Puddu, G; Quintans, C; Ramos, S; Ramello, L; Rato-Mendes, P; Riccati, L; Romana, A; Santos, H; Saturnini, P; Scalas, E; Scomparin, E; Serci, S; Shahoyan, R; Sigaudo, F; Silva, S; Sitta, M; Sonderegger, P; Tarrago, X; Topilskaya, N S; Usai, G L; Vercellin, Ermanno; Villatte, L; Willis, N

    2002-01-01

    The main goal of the NA50 experiment is to study the J/ psi suppression pattern in Pb-Pb interactions, at 158 GeV/c per nucleon at the CERN SPS. We present here the results from the 1996 and 1998 data taking periods. We used new event selection procedures, different analysis techniques and different event centrality estimators and we now confirm and extend our previous observation that the J/ psi is anomalously suppressed when going from peripheral to central Pb-Pb collisions. We observe that in peripheral collisions the J/ psi cross section per nucleon-nucleon collision agrees with the pattern inferred from a wide range of measurements with lighter systems, from p-p to S-U. When the collisions become more central a clear departure from this behavior is observed. The 1996 data show a sudden drop in the J/ psi production yield for transverse energy values above 40 GeV. The 1998 data provide a big improvement in the study of the most central region, where a second change in the pattern becomes visible. This sup...

  6. Probing Shell Correction at High Spin by Neutron Emission of Doubly Magic Nuclei 208pb and 132Sn

    Institute of Scientific and Technical Information of China (English)

    YEWei

    2005-01-01

    Shell effects in particle emission for two doubly magic nuclei 132Sn and 208pb were studied in the framework of Smoluchowski equation taking into account temperature and spin-dependent shell correction. It is shown that the shelle ffects in the emission of pre-scission neutrons are sensitive to the spin dependence of the shell correction at a moderate excitation energy. Therefore, we propose to use neutron multiplicity as an observable to probe the shell correction at high spins.

  7. Probing Shell Correction at High Spin by Neutron Emission of Doubly Magic Nuclei 208pb and 132Sn

    Institute of Scientific and Technical Information of China (English)

    YE Wei

    2005-01-01

    Shell effects in particle emission for two doubly magic nuclei 132 Sn and 208 Pb were studied in the framework of Smoluchowski equation taking into account temperature and spin-dependent shell correction. It is shown that the shell effects in the enission of pre-scission neutrons are sensitive to the spin dependence of the shell correction at a moderate excitation energy. Therefore, we propose to use neutron multiplicity as an observable to probe the shell correction at high spins.

  8. Investigation of Central Pb-Pb Interactions at Energies of 160 GeV/Nucleon with the Help of the Emulsion Magnetic Chamber

    CERN Multimedia

    2002-01-01

    % EMU15 \\\\ \\\\ The aim of this experiment is to investigate high energy heavy ion central collisions by the use of emulsion magnetic chamber with high spatial resolution. The emulsion chamber consists of 50~emulsion layers 50~microns thick each coated on 25~microns mylar base. A thin lead target plate 300~microns thick is installed immediately in front of the first emulsion layer. It is placed in the transverse magnetic field B~$\\sim$~2~Tesla and is to be installed perpendicularly to Pb nucleus beam. This set-up enables to measure full 3-momenta and charge signs of secondary particles. \\\\ \\\\Specific goal is to carry out detailed analysis of individual events with super high multiplicity of secondaries. These data are to be used for investigation of properties of super hot/dense matter, in particular to look for and analyze possible manifestations of quark-gluon plasma in central Pb-Pb collisions at energies of 160~GeV/nucleon.

  9. Crystal structure and band structure calculations of Pb1/3TaS2 and Sn1/3NbS2

    NARCIS (Netherlands)

    Fang, C.M; Wiegers, G.A; Meetsma, A.; de Groot, R.A.; Haas, C

    The crystal structures of Pb1/3TaS2 and Sn1/3NbS2 were determined using single-crystal X-ray diffraction. The space group is P6(3)22 and the unit cell dimensions are: a = 5.759(1), c = 14.813(1)Angstrom and a = 5.778(1), c = 14.394(1)Angstrom, for the Pb and Sn compounds, respectively. The

  10. Analytisch-chemische aspecten van de bepaling van As, Ca, Cd, Sb, Sn, Pb, Zn in MVS-filterdestruaten met ICP-MS

    NARCIS (Netherlands)

    Velde-Koerts T van der; Lesquillier AI; Ritsema R; LAC

    1995-01-01

    In dit onderzoek werd een ICP-MS-methode ontwikkeld voor de bepaling van Ca, Zn, As, Cd, Sb, Sn en Pb in filterdestruaten. De onderste analysegrens is 30 ng/l Sb, 60 ng/l Cd, 200 ng/l As, 300 ng/l Sn, 400 ng/l Pb, 4 mug/l Zn en 20 mug/l Ca ; de precisie is beter dan 7% RSD voor Ca, 4% RSD voor A

  11. Analytisch-chemische aspecten van de bepaling van As, Ca, Cd, Sb, Sn, Pb, Zn in MVS-filterdestruaten met ICP-MS

    NARCIS (Netherlands)

    Velde-Koerts T van der; Lesquillier AI; Ritsema R; LAC

    1995-01-01

    In dit onderzoek werd een ICP-MS-methode ontwikkeld voor de bepaling van Ca, Zn, As, Cd, Sb, Sn en Pb in filterdestruaten. De onderste analysegrens is 30 ng/l Sb, 60 ng/l Cd, 200 ng/l As, 300 ng/l Sn, 400 ng/l Pb, 4 mug/l Zn en 20 mug/l Ca ; de precisie is beter dan 7% RSD voor Ca, 4% RSD voor

  12. Direct bandgap GeSn microdisk lasers at 2.5 μm for monolithic integration on Si-platform

    OpenAIRE

    Wirths, S.; Geiger, R.; Schulte-Braucks, C; Von Den Driesch, N; Stange, D; Zabel, T.; Ikonic, Z; Hartmann, JM; Mantl, S; Sigg, H; Grutzmacher, D; Buca, D.

    2016-01-01

    We report on the first experimental demonstration of direct bandgap group IV GeSn microdisk (MD) lasers (λem=2.5 μm) grown on Si(001). The evidence of lasing is supported by a detailed analysis of strain-dependent emission characteristics of GeSn alloys with xSn ≥ 12 at.%. Residual compressive strain within the layer is relieved via under-etching of the MD enabling increased energy offsets up to EL-EΓ=80 meV. The lasing threshold and max. temperature amount to 220 kW/cm2 and 135 K, respective...

  13. Radiative muon capture on Al, Si, Ca, Mo, Sn, and Pb

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, D.S.; Serna-Angel, A.; Ahmad, S.; Azuelos, G.; Bertl, W.; Blecher, M.; Chen, C.Q.; Depommier, P.; von Egidy, T.; Gorringe, T.P.; Hasinoff, M.D.; Henderson, R.S.; Larabee, A.J.; Macdonald, J.A.; McDonald, S.C.; Poutissou, J.; Poutissou, R.; Robertson, B.C.; Sample, D.G.; Taylor, G.N.; Wright, D.H.; Zhang, N.S. (Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States) University of British Columbia, Vancouver, British Columbia, V6T 1Z5 (Canada) TRIUMF, Vancouver, British Columbia, V6T 2A3 (Canada) Universite de Montreal, Montreal, Quebec, H3C 3J7 (Canada) Universite de Montreal, Montreal, Quebec, H3C 3J7 (Canada) Paul Scherrer Institute, CH-5234, Villigen (Switzerland) University of Kentucky, Lexington, Kentucky 40506 (United States) University of Melbourne, Parkville, Victoria3001, (Australia) Queen' s University, Kingston, Ontario, K7L 3N6 (Canada))

    1992-09-01

    The branching ratio for radiative muon capture (RMC), relative to the nonradiative process, is sensitive to {ital g}{sub {ital p}}, the induced pseudoscalar coupling constant of the weak hadronic current. The photon energy spectra from RMC on {sup 27}Al, {sup 28}Si, {sup 40}Ca, {sup nat}Mo, {sup nat}Sn, and {sup nat}Pb have been measured using a high-acceptance pair spectrometer. The measured partial branching ratios, {ital R}{sub {gamma}}, for photons of {ital E}{sub {gamma}}{gt}57 MeV are 1.43{plus minus}0.13, 1.93{plus minus}0.18, 2.09{plus minus}0.19, 1.11{plus minus}0.11, 0.98{plus minus}0.09, and 0.60{plus minus}0.07 respectively, in units of 10{sup {minus}5}. The results confirm the previously observed suppression of {ital R}{sub {gamma}} with increasing {ital Z} for {ital Z}{gt}20. For {sup 40}Ca the present result is in good agreement with previous measurements. For the heavier nuclei, the results are compared with two recent calculations performed in the Fermi-gas model. In one case the data indicate a complete quenching of {ital g}{sub {ital p}}, but the more recent calculation does not reproduce the data for any value of {ital g}{sub {ital p}}.

  14. Investigation of Sn-Pb solder bumps of prototype photo detectors for the LHCb experiment

    CERN Document Server

    Delsante, M L; Arnau-Izquierdo, G

    2004-01-01

    The Large Hadron Collider (LHC) is now under construction at the European Organization for Nuclear Research (CERN). LHCb is one of the dedicated LHC experiments, allowing high energy proton-proton collisions to be exploited. This paper presents the results of the metallurgic studies carried out on Sn-Pb solder bumps of prototype vacuum photo detectors under development for LHCb, and in particular for the ring imaging Cherenkov-hybrid photo diode (RICH-HPD) project. These detectors encapsulate, in a vacuum tube, an assembly made of two silicon chips bonded together by a matrix of solder bumps. Each bump lies on a suitable system of under-bump metallic layers ensuring mechanical and electrical transition between the chip pad and the solder alloy. During manufacturing of the detector, bump-bonded (BB) assemblies are exposed to severe heat cycles up to 400 degree C inducing, in the present fabrication process, a clear degradation of electrical connectivity. Several investigations such as microstructural observati...

  15. Performance evaluation of high-detectivity p-i-n infrared photodetector based on compressively-strained Ge0.964Sn0.036/Ge multiple quantum wells by quantum modelling

    Science.gov (United States)

    Yahyaoui, N.; Sfina, N.; Lazzari, J.-L.; Bournel, A.; Said, M.

    2015-08-01

    GeSn/Ge p-i-n photodetectors with practical Ge0.964Sn0.036 active layers are theoretically investigated. First, we calculated the electronic band parameters for the heterointerfaces between strained Ge1-xSnx and relaxed (001)-oriented Ge. The carrier transport in a p-i-n photodiode built on a ten-period Ge0.964Sn0.036/Ge multiple quantum well absorber was then analyzed and numerically simulated within the Tsu-Esaki formalism by self-consistently solving the Schrödinger and Poisson equations, coupled to the kinetic rate equations. Photodetection up to a 2.1 μm cut-off wavelength is achieved. High responsivities of 0.62 A W-1 and 0.71 A W-1 were obtained under a reverse bias voltage of -3 V at peak wavelengths of 1550 nm and 1781 nm, respectively. Even for this low Sn-fraction, it is found that the photodetector quantum efficiency (49%@1.55 μm) is higher than those of comparable pure-Ge devices at room temperature. Detectivity of 3.8 × 1010 cm Hz1/2 W-1 and 7.9 × 1010 cm Hz1/2 W-1 at -1 V and -0.5 V, respectively, is achievable at room temperature for a 1550 nm wavelength peak of responsivity. This work represents a step forward in developing GeSn/Ge based infrared photodetectors.

  16. Theoretical insights into a potential lead-free hybrid perovskite: substituting Pb2+ with Ge2+

    Science.gov (United States)

    Sun, Ping-Ping; Li, Quan-Song; Yang, Li-Na; Li, Ze-Sheng

    2016-01-01

    In recent years, perovskite solar cells have been considerably developed, however the lead in the absorber MAPbI3 is a potential threat to the environment. To explore potential alternatives, the structural and electronic properties of MAGeX3 (X = Cl, Br, I) were investigated using different density functional theory methods, including GGA-PBE, PBE-SOC, HSE06 and HSE-SOC. The results implied that MAGeI3 exhibits an analogous band gap, substantial stability, remarkable optical properties, and significant hole and electron conductive behavior compared with the so far widely used absorber MAPbI3. Moreover, the calculations revealed that the energy splitting resulting from the spin-orbit coupling is evident on Pb, moderate on Ge, I and Br, and negligible on Cl. Our work not only sheds some light on screening novel absorbers for perovskite solar cells but also deepens the understanding of these functional materials.In recent years, perovskite solar cells have been considerably developed, however the lead in the absorber MAPbI3 is a potential threat to the environment. To explore potential alternatives, the structural and electronic properties of MAGeX3 (X = Cl, Br, I) were investigated using different density functional theory methods, including GGA-PBE, PBE-SOC, HSE06 and HSE-SOC. The results implied that MAGeI3 exhibits an analogous band gap, substantial stability, remarkable optical properties, and significant hole and electron conductive behavior compared with the so far widely used absorber MAPbI3. Moreover, the calculations revealed that the energy splitting resulting from the spin-orbit coupling is evident on Pb, moderate on Ge, I and Br, and negligible on Cl. Our work not only sheds some light on screening novel absorbers for perovskite solar cells but also deepens the understanding of these functional materials. Electronic supplementary information (ESI) available: Optimized structures of the MAPbI3 and MASnI3 perovskites, band structures of the different

  17. Magnetic excitations in the triangular antiferromagnets Mn3Sn and Mn3Ge

    Science.gov (United States)

    Cable, J. W.; Wakabayashi, N.; Radhakrishna, P.

    1993-09-01

    Inelastic neutron scattering was used to study the magnetic excitations of the triangular antiferromagnets Mn3Sn and Mn3Ge. These compounds have itinerant d electrons and large magnetic moments localized at the Mn sites and may be regarded as materials that lie in the intermediate regime between local-moment and itinerant-electron systems. The spin-wave spectra exhibit steep dispersion and strong damping, which is characteristic behavior of itinerant-electron systems. Nevertheless, it is useful to analyze the data in terms of a local-moment model with anisotropy. We find the data are remarkably well described by this model with exchange parameters extending to fifth-nearest neighbors and with both axial- and basal-plane anisotropy. The axial-anisotropy parameters were determined from the uniform out-of-plane spin fluctuation, and the signs show that the spins are confined to the basal plane. The second-order basal-plane anisotropy constants were determined by satisfying both the magnitude of the weak basal-plane ferromagnetic moments and the observed splitting of a doubly degenerate acoustic-spin-wave branch. The sixth-order basal-plane anisotropy was determined by adjusting to the observed energy gap associated with spin fluctuations within the basal plane. The exchange parameters have the correct signs to stabilize the triangular antiferromagnetic structure but yield Néel temperatures that are higher than those observed by a factor of 3 or 4. This overestimation of the Néel temperature is not an uncommon result when a local moment model is applied to an itinerant-electron system.

  18. Low-temperature (˜180 °C) position-controlled lateral solid-phase crystallization of GeSn with laser-anneal seeding

    Science.gov (United States)

    Matsumura, Ryo; Chikita, Hironori; Kai, Yuki; Sadoh, Taizoh; Ikenoue, Hiroshi; Miyao, Masanobu

    2015-12-01

    To realize next-generation flexible thin-film devices, solid-phase crystallization (SPC) of amorphous germanium tin (GeSn) films on insulating substrates combined with seeds formed by laser annealing (LA) has been investigated. This technique enables the crystallization of GeSn at controlled positions at low temperature (˜180 °C) due to the determination of the starting points of crystallization by LA seeding and Sn-induced SPC enhancement. The GeSn crystals grown by SPC from LA seeds showed abnormal lateral profiles of substitutional Sn concentration. These lateral profiles are caused by the annealing time after crystallization being a function of distance from the LA seeds. This observation of a post-annealing effect also indicates that GeSn with a substitutional Sn concentration of up to ˜10% possesses high thermal stability. These results will facilitate the fabrication of next-generation thin-film devices on flexible plastic substrates with low softening temperatures (˜250 °C).

  19. Hydrogen-surfactant-mediated epitaxy of Ge1- x Sn x layer and its effects on crystalline quality and photoluminescence property

    Science.gov (United States)

    Nakatsuka, Osamu; Fujinami, Shunsuke; Asano, Takanori; Koyama, Takeshi; Kurosawa, Masashi; Sakashita, Mitsuo; Kishida, Hideo; Zaima, Shigeaki

    2017-01-01

    The effect of hydrogen-surfactant-mediated molecular beam epitaxy (MBE) growth of Ge1- x Sn x layer on Ge(001) substrate on crystalline quality and photoluminescence (PL) property has been investigated. The effect of irradiation of atomic hydrogen (H) generated by dissociating molecular hydrogen (H2) were examined during the MBE growth. H irradiation significantly improves the surface morphology with the enhancement of the two-dimensional growth of the Ge1- x Sn x epitaxial layer. Enhanced diffuse scattering is observed in the X-ray diffraction profile, indicating a high density of point defects. In the PL spectrum of the H2-irradiated Ge1- x Sn x layer, two components are observed, suggesting the radiative recombination with both indirect and direct transitions, while one component related to the direct transition is observable in the H-irradiated sample. The postdeposition annealing in nitrogen ambient at as low as 220 °C decreases the PL intensity of the H-irradiated Ge1- x Sn x layer, although the intensity is recovered after annealing at 300 °C, suggesting the annihilation of point defects in the Ge1- x Sn x layer.

  20. High carrier mobility of Sn-doped polycrystalline-Ge films on insulators by thickness-dependent low-temperature solid-phase crystallization

    Science.gov (United States)

    Sadoh, Taizoh; Kai, Yuki; Matsumura, Ryo; Moto, Kenta; Miyao, Masanobu

    2016-12-01

    To realize the advanced thin-film transistors (TFTs), high-carrier-mobility semiconductor films on insulator structures should be fabricated with low-temperature processing conditions (≤500 °C). To achieve this, we investigated the solid-phase crystallization of amorphous-GeSn films on insulating substrates under a wide range of Sn concentrations (0%-20%), film thicknesses (30-500 nm), and annealing temperatures (380-500 °C). Our results reveal that a Sn concentration close to the solid solubility of Sn in Ge (˜2%) is effective in increasing the grain-size of poly-GeSn. In addition, we discovered that the carrier mobility depends on the film thickness, where the mobilities are determined by the counterbalance between two different carrier scattering mechanisms. Here, vacancy-related defects dominate the carrier scattering near the insulating substrates (≤˜120 nm), and grain-size determined by bulk nucleation dominates the grain-boundary scattering of thick films (≥˜200 nm). Consequently, we obtained the maximum mobilities in samples with a Sn concentration of 2% and a film thickness of 200 nm. The effect of increasing the grain-size of poly-GeSn by lowering the annealing temperature was also clarified. By combining these results, a very high carrier mobility of 320 cm2/Vs was obtained at a low temperature of 380 °C. This mobility is about 2.5 times as high as previously reported data for Ge and GeSn films grown at low temperatures (≤500 °C). Our technique therefore opens up the possibility of high-speed TFTs for use in the next generation of electronics.

  1. Strained Germanium-Tin (GeSn) P-Channel Metal-Oxide-Semiconductor Field-Effect Transistors Featuring High Effective Hole Mobility

    Science.gov (United States)

    Liu, Yan; Yan, Jing; Wang, Hongjuan; Cheng, Buwen; Han, Genquan

    2015-06-01

    Compressively strained and p-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) are fabricated with low-temperature surface passivation. High crystallinity GeSn films epitaxially grown on a Ge(001) substrate are used for the device fabrication. The impacts of the Sn composition on the subthreshold swing , threshold voltage , on-state current , and effective hole mobility of the devices are investigated. GeSn pMOSFETs with different Sn compositions show a similar , indicating almost the same midgap density of interface states . A positive shift of with an increase of the Sn composition is observed. A pMOSFET exhibits a significant improvement in as compared to a device with a lower Sn composition, which is due to the superior hole mobility in a device with a higher Sn composition. pMOSFETs achieve a peak effective hole mobility of , which is much higher than that of devices. The enhancement of the compressive strain and chemical effect in the channel region with increased Sn composition leads to an improvement of.

  2. Blue cooperative emission in Yb3+ - doped GeO2 - PbO glasses

    Directory of Open Access Journals (Sweden)

    Vanessa Duarte Del Cacho

    2006-03-01

    Full Text Available Investigation of the blue cooperative luminescence in a binary composition of GeO2-PbO glasses with different Yb3+ concentrations is reported. High refractive index (1.96 and large transmission window (0.4 up to 5.0 µm are characteristics of this vitreous system. Luminescence and lifetime measurements in the visible and near infrared regions were performed to investigate the spectroscopic characteristics of the glasses. Visible emission around 507 nm was detected in all samples. The visible emission intensity increases with the Yb2O3 content at least up to 2.0 wt. (%, that represents the maximum Yb2O3 concentration possible for this glass system. The visible lifetimes are about half of their respective near infrared ones, and the blue luminescence comes from a cooperative process. A rate equation was used to describe the behavior of the cooperative emission intensity as a function of Yb2O3 concentration; a good agreement with the calculated and measured cooperative luminescence was achieved.

  3. SuperTIGER scintillator detector calibration with 30 GeV/nucleon Pb and its fragments

    Science.gov (United States)

    Sasaki, Makoto

    2016-07-01

    The SuperTIGER (Super Trans-Iron Galactic Element Recorder) long-duration balloon instrument has measured the abundances of galactic cosmic-ray elements to provide sensitive tests and clarification of the OB-association model of Galactic cosmic-ray origins. More than 600 nuclei with atomic number Z > 30 were observed on its first flight and the abundances of nuclei have been determined with clear individual element resolution and high statistical precision for 30 energy 30 GeV/nucleon Pb and its fragments to measure the saturation response of the scintillator detectors, which are essential to determine the abundances of nuclei with atomic number Z > 40. The beamtest results have been used to optimize the Geant4 simulation to represent the flight data, and will be used to interpret the flight data to extend the abundance determination to about _{60}Nd. SuperTIGER was developed by Washington University in St. Louis, NASA Goddard Flight Center, the California Institute of Technology, Jet Propulsion Laboratory, and the University of Minnesota.

  4. Energy and centrality dependence of $\\overline{p}$ and $p$ production and the $\\overline{\\lambda}/\\overline{p}$ ratio in Pb+Pb collisions between 20A GeV and 158A GeV

    CERN Document Server

    Alt, C; Baatar, B; Barna, D; Bartke, Jerzy; Betev, L; Bialkowska, H; Blume, C; Boimska, B; Botje, M; Braconik, J; Bramm, R; Bruncic, P; Cerny, V; Christakoglou, P; Chvala, O; Cramer, J G; Csató, P; Dinkelaker, P; Eckardt, V; Flierl, D; Fodor, Z; Foka, P; Friese, V; Gál, J; Gazdzicki, M; Genchev, V; Georgopoulos, G; Gladysz-Dziadus, E; Grebieszkow, K; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kliement, M; Kniege, S; Kolesnikov, V I; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Laslo, A; Van Leeuwen, M; Lévai, Peter; Litov, L; Lungwit5z, B; Makariev, M; Malakhov, A I; Mateev, M; Melkumov, G L; Mischke, A; Mitrovski, M; Molnár, J; Mrówczynski, S; Nicolic, V; Pálla, G; Panagiotou, A D; Panayotov, D; Petridis, A; Pikna, M; Prindle, D; Pühlhofer, F; Renfordt, R; Roland, C; Stefanel, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Schuster, T; Seyboth, T; Siklér, F; Sitár, B; Skrzypczak, E; Stefanek, G; Stock, R; Strabel, C; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Szymanski, P; Trubnikov, V; Varga, D; Vassiliou, Maria; Veres, G I; Vesztergombi, G; Vranic, D; Wetzler, A; Wlodarczyk, Z; Yoo, I K; Zimányi, J

    2006-01-01

    The transverse mass m/sub t/ distributions for antiprotons are measured at midrapidity for minimum bias Pb+Pb collisions at 158A GeV and for central Pb+Pb collisions at 20A, 30A, 40A, and 80A GeV beam energies in the fixed target experiment NA49 at the CERN SPS. The rapidity density dn/dy, inverse slope parameter T, and mean transverse mass left angle bracketm/sub t/right angle bracket derived from the m/sub t/ distributions are studied as a function of the incident energy and the collision centrality and compared to the relevant data on proton production. The shapes of the m/sub t/ distributions of pmacron and p are very similar. The ratios of the particle yields, pmacron/p and Lambda/pmacron, are also analyzed. The pmacron/p ratio exhibits an increase with decreasing centrality and a steep rise with increasing beam energy. The Lambda/pmacron ratio increases beyond unity with decreasing beam energy.

  5. Cubic Form of Pb2-xSnxS2 Stabilized through Size Reduction to the Nanoscale

    Energy Technology Data Exchange (ETDEWEB)

    Soriano, Ronald B; Malliakas, Christos D; Wu, Jinsong; Kanatzidis, Mercouri G [NWU

    2012-04-02

    We demonstrate the synthesis of semiconductor Pb2-xSnxS2 nanocrystals with a cubic rock salt crystal structure in a composition range where this structure is unstable in the bulk. The cubic Pb2-xSnxS2 nanocrystals were prepared using a modified hot injection colloidal synthetic route. The x value is in the range 0.40 < x < 1. Even though these compositions lie in a region of the PbS-SnS phase diagram where no single phase exists, and despite the fact that PbSnS2 is a distorted orthorhombic phase, the Pb2-xSnxS2 nanocrystals are single phase solid solutions with cubic NaCl-type structure. Experimental evidence for this derives from powder X-ray diffraction (PXRD), electron diffraction, and pair distribution function (PDF) analysis. Elemental compositions determined using scanning transmission electron microscopy/energy dispersive spectroscopy (STEM/EDS), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and electron energy loss spectroscopy (EELS) reveal a composition close to the nominal ones. The band gaps of the Pb2-xSnxS2 nanocrystals (0.52-0.57 eV) are blue-shifted by quantum confinement relative to that of the hypothetical cubic PbSnS2 phase which density functional theory (DFT) calculations show to be much narrower (0.2 eV) than in the case of orthorhombic PbSnS2 (1.1 eV). The Pb2-xSnxS2 nanocrystals exhibit a well-defined band gap in the near-IR region and are stable up to 300 °C above which they phase separate into cubic PbS and orthorhombic α-SnS.

  6. Transiciones de fase y fenómenos colectivos en la interfase 1-3 ML-Sn - Ge (111)

    OpenAIRE

    2009-01-01

    En este trabajo se ha estudiado la interfase 1/3 ML-SnGe(111) mediante PES, STM y LEED. Esta interfase es un sistema modelo para el estudio de las correlaciones electrónicas en física del estado sólido.El estudio de la estructura electrónica cerca del nivel de Fermi de la fase (3x3) entre 139 K y 60 K muestra que esta fase es metálica. La celda unidad de la reconstrucción (3×3) consiste un átomo de Sn desplazado hacia arriba y dos desplazados hacia abajo (modelo 1U2D). A partir de medidas de ...

  7. Growth and applications of GeSn-related group-IV semiconductor materials

    Science.gov (United States)

    Zaima, Shigeaki; Nakatsuka, Osamu; Taoka, Noriyuki; Kurosawa, Masashi; Takeuchi, Wakana; Sakashita, Mitsuo

    2015-08-01

    We review the technology of Ge1-xSnx-related group-IV semiconductor materials for developing Si-based nanoelectronics. Ge1-xSnx-related materials provide novel engineering of the crystal growth, strain structure, and energy band alignment for realising various applications not only in electronics, but also in optoelectronics. We introduce our recent achievements in the crystal growth of Ge1-xSnx-related material thin films and the studies of the electronic properties of thin films, metals/Ge1-xSnx, and insulators/Ge1-xSnx interfaces. We also review recent studies related to the crystal growth, energy band engineering, and device applications of Ge1-xSnx-related materials, as well as the reported performances of electronic devices using Ge1-xSnx related materials.

  8. Effect of a transverse magnetic field on solidification morphology and microstructures of pure Sn and Sn-15 wt% Pb alloys grown by a Czochralski method

    Science.gov (United States)

    Shen, Zhe; Zhong, Yunbo; Wang, Huai; Ren, Weili; Lei, Zuosheng; Ren, Zhongming

    2015-12-01

    The pure Sn and Sn-15 wt% Pb alloys were grown by a Czochralski method under various magnetic flux densities in this paper. The influence of thermoelectric magnetic (TEM) flows and buoyancy flows on solidification morphology, macrosegregation and microstructures had been investigated experimentally, and the velocity magnitude of TEM flows and buoyancy flows had been studied by 3D numerical simulations. The experimental results indicate that the modification of solidification morphology and microstructures is attributed to the unidirectional Pb solutes transport caused by TEM flows. The 3D numerical simulations results show that the buoyancy flows dominate the flows in the melt under a weak transverse magnetic field (B≤0.43 T), and the unidirectional TEM flows at the vicinity of solid-liquid interface become the dominant flows in the melt with the increase of magnetic field. The interaction of TEM flows and buoyancy flows affecting solidification morphology and microstructures during directional solidification of alloys by the Czochralski method under various magnetic flux densities has been discussed and a corresponding simple evolution mechanism of dendritic growth has been proposed.

  9. Temperature Dependent Spectral Response and Detectivity of GeSn Photoconductors on Silicon for Short Wave Infrared Detection

    Science.gov (United States)

    2014-01-01

    wavelength infrared InGaAs and HgCdTe photodiodes," in 1998 U S Workshop on the Physics and Chemistry of II-VI Materials, J. Electron. Mater. 1998), 630...Engineering, University of Arkansas, Fayetteville, AR 72701, USA 2Department of Physics , University of Massachusetts Boston, Boston, MA 02125, USA 3ASM...Vandervorst, R. Loo, M. Caymax, K. Temst, and M. Heyns, "Crystalline Properties and Strain Relaxation Mechanism of CVD Grown GeSn," ECS J. of Solid State

  10. Low-mass lepton pair production in Pb-Au collisions at 40 A center dot GeV

    CERN Document Server

    Adamova, D; Appelshäuser, H; Belaga, V; Braun-Munzinger, P; Cherlin, A; Damjanovic, S; Dietel, T; Dietrich, L; Drees, A; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Zeev; Garabatos, C; Glässel, P; Hering, G; Holeczek, J; Kushpil, V; Lenkeit, B C; Maas, A; Marin, A; Milosevic, J; Milov, A; Miskowiec, D; Panebratsev, Yu A; Petchenova, O Yu; Petrácek, V; Pfeiffer, A; Rak, J; Ravinovich, I; Rehak, P; Richter, M; Sako, H; Schmitz, W; Schükraft, Jürgen; Sedykh, S; Seipp, W; Shimansky, S S; Slívova, J; Specht, H J; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, Itzhak; Wessels, J P; Wienold, T; Windelband, B; Wurm, J P; Xie, W; Yurevich, S; Yurevich, V

    2003-01-01

    The CERES/NA45 experiment at the CERN SPS has previously measured e **+e**- pair production in 160 A center dot GeV Pb-Au collisions. In the mass region m greater than 0.2 GeV/c**2, an enhancement of 2.7 plus or minus 0.4(stat.) plus or minus 0.5(syst.) compared to the expectation from known hadronic decay sources was observed. In the 40 A center dot GeV data taken in 1999, an enhancement is again found; a preliminary analysis gives an even larger value of 5.0 plus or minus 1.3(stat.). The results are compared to theoretical model calculations based on pi**+ pi**- annihilation with a modified rho- propagator; they may be related to chiral symmetry restoration. 17 Refs.

  11. Effects of post-deposition annealing on crystalline state of GeSn thin films sputtered on Si substrate and its application to MSM photodetector

    Science.gov (United States)

    Mahmodi, H.; Hashim, M. R.

    2016-10-01

    Ge1-x Sn x alloy thin films were prepared by co-sputtering from Ge and Sn targets on a Si (100) substrate at room temperature, and were then heated at temperature ranging from 200 {}\\circ {{C}} to 500 {}\\circ {{C}} in N2 ambient to reduce the disorder and defects and increase the crystalline quality of the films. Images obtained by field emission scanning electron microscopy revealed that the as-grown and all annealed samples displayed a densely packed morphology. The atomic percent composition of Sn in the as-grown Ge1-x Sn x film is 5.7 at % . Energy-dispersive x-ray spectroscopy results showed Sn surface segregation after heat treatment, as the Sn composition is reduced to 3.3 at % for the film annealed at 500 {}\\circ C. The Raman analysis showed that the only observed phonon mode is attributed to Ge-Ge vibrations. The Raman spectra of as-sputtered and annealed films revealed their nanocrystalline-amorphous nature. The samples annealed at lower temperature exhibited higher phonon intensity, indicating the improvement of crystallinity of the film. The optoelectronic characteristics of fabricated metal-semiconductor-metal photodetectors on the annealed sample at 200 {}\\circ {{C}} and the as-sputtered sample were studied in the dark and under illumination. Compared with the as-sputtered one, the annealed sample showed lower dark current and higher current gain of 209. The results showed the potentiality of using the sputtering technique to produce GeSn layer for optoelectronics application.

  12. Development of nanotopography during SIMS characterization of thin films of Ge{sub 1−x}Sn{sub x} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Secchi, M., E-mail: secchi@fbk.eu [Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo, TN (Italy); Department of Physics, University of Trento, Via Sommarive 14, 38123 Trento (Italy); Demenev, E. [Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo, TN (Italy); Department of Molecular Science and Nanosystems, Ca’Foscari University, Dorsoduro 2137, 30123 Venice (Italy); Colaux, J.L. [Ion Beam Centre, Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, Surrey, England (United Kingdom); Giubertoni, D.; Dell’Anna, R.; Iacob, E. [Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo, TN (Italy); Gwilliam, R.M.; Jeynes, C. [Ion Beam Centre, Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, Surrey, England (United Kingdom); Bersani, M. [Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo, TN (Italy)

    2015-11-30

    Highlights: • SIMS protocol to measure high Sn concentration in GeSn alloy is proposed. • Cs{sup +} as incidence beam, collecting positive ions MCs{sup +} was the chosen configuration. • Applied sputtering conditions induced an early formation of surface topography. • Unusual dot and ripple evolution at oblique incidence angle on Ge were studied. • Two different mechanisms seem to be involved: ripple formation and nanovoids in Ge. - Abstract: This work presents a study of application of secondary ion mass spectrometry (SIMS) to measure tin concentration in Ge{sub 1−x}Sn{sub x} alloy with x higher than solid solubility ∼1%, i.e. well above the diluted regime where SIMS measurements usually provide the most reliable quantitative results. SIMS analysis was performed on Sn{sup +} ion implanted Ge films, epitaxially deposited on Si, and on chemical vapor deposition deposited Ge{sub 0.93}Sn{sub 0.07} alloy. Three SIMS conditions were investigated, varying primary beam ion species and secondary ion polarity keeping 1 keV impact energy. Best depth profile accuracy, best agreement with the fluences measured by Rutherford backscattering spectrometry, good detection limit (∼1 × 10{sup 17} at/cm{sup 3}) and depth resolution (∼2 nm/decade) are achieved in Cs{sup +}/SnCs{sup +} configuration. However, applied sputtering conditions (Cs{sup +} 1 keV, 64° incidence vs. normal) induced an early formation of surface topography on the crater bottom resulting in significant variation of sputtering yield. Atomic force microscopy shows a peculiar topography developed on Ge: for oblique incidence, a topography consisting in a sequence of dots and ripples was observed on the crater bottom. This behavior is unusual for grazing incidence and has been observed to increase with the Cs{sup +} fluence. Rotating sample during sputtering prevents this ripple formation and consequently improves the depth accuracy.

  13. Relativistic GW calculations on CH3NH3PbI3 and CH3NH3SnI3 perovskites for solar cell applications.

    Science.gov (United States)

    Umari, Paolo; Mosconi, Edoardo; De Angelis, Filippo

    2014-03-26

    Hybrid AMX3 perovskites (A = Cs, CH3NH3; M = Sn, Pb; X = halide) have revolutionized the scenario of emerging photovoltaic technologies, with very recent results demonstrating 15% efficient solar cells. The CH3NH3PbI3/MAPb(I(1-x)Cl(x))3 perovskites have dominated the field, while the similar CH3NH3SnI3 has not been exploited for photovoltaic applications. Replacement of Pb by Sn would facilitate the large uptake of perovskite-based photovoltaics. Despite the extremely fast progress, the materials electronic properties which are key to the photovoltaic performance are relatively little understood. Density Functional Theory electronic structure methods have so far delivered an unbalanced description of Pb- and Sn-based perovskites. Here we develop an effective GW method incorporating spin-orbit coupling which allows us to accurately model the electronic, optical and transport properties of CH3NH3SnI3 and CH3NH3PbI3, opening the way to new materials design. The different CH3NH3SnI3 and CH3NH3PbI3 electronic properties are discussed in light of their exploitation for solar cells, and found to be dominantly due to relativistic effects. These effects stabilize the CH3NH3PbI3 material towards oxidation, by inducing a deeper valence band edge. Relativistic effects, however, also increase the material band-gap compared to CH3NH3SnI3, due to the valence band energy downshift (~0.7 eV) being only partly compensated by the conduction band downshift (~0.2 eV).

  14. Relativistic GW calculations on CH3NH3PbI3 and CH3NH3SnI3 Perovskites for Solar Cell Applications

    Science.gov (United States)

    Umari, Paolo; Mosconi, Edoardo; de Angelis, Filippo

    2014-03-01

    Hybrid AMX3 perovskites (A = Cs, CH3NH3; M = Sn, Pb; X = halide) have revolutionized the scenario of emerging photovoltaic technologies, with very recent results demonstrating 15% efficient solar cells. The CH3NH3PbI3/MAPb(I1-xClx)3 perovskites have dominated the field, while the similar CH3NH3SnI3 has not been exploited for photovoltaic applications. Replacement of Pb by Sn would facilitate the large uptake of perovskite-based photovoltaics. Despite the extremely fast progress, the materials electronic properties which are key to the photovoltaic performance are relatively little understood. Density Functional Theory electronic structure methods have so far delivered an unbalanced description of Pb- and Sn-based perovskites. Here we develop an effective GW method incorporating spin-orbit coupling which allows us to accurately model the electronic, optical and transport properties of CH3NH3SnI3 and CH3NH3PbI3, opening the way to new materials design. The different CH3NH3SnI3 and CH3NH3PbI3 electronic properties are discussed in light of their exploitation for solar cells, and found to be dominantly due to relativistic effects. These effects stabilize the CH3NH3PbI3 material towards oxidation, by inducing a deeper valence band edge. Relativistic effects, however, also increase the material band-gap compared to CH3NH3SnI3, due to the valence band energy downshift (~0.7 eV) being only partly compensated by the conduction band downshift (~0.2 eV).

  15. Magnetic properties of R{sub 3}Cu{sub 4}X{sub 4} (R=Gd-Er; X=Ge, Sn) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Szytula, A.; Wawrzynska, E.; Penc, B.; Stuesser, N.; Zygmunt, A

    2003-04-01

    In this work, the results of magnetic and neutron-diffraction studies of a new series of intermetallic compounds R{sub 3}Cu{sub 4}X{sub 4} (R=Gd-Er; X=Ge, Sn) are presented. The X-ray and neutron-diffraction data indicate that these compounds crystallise in the orthorhombic Gd{sub 3}Cu{sub 4}Ge{sub 4}-type structure (space group Immm). In this structure, the rare-earth atoms occupy two non-equivalent crystallographic positions: 2d and 4e. The magnetometric and neutron diffraction measurements indicate that the R{sub 3}Cu{sub 4}X{sub 4} (R=Gd-Er; X=Ge, Sn) compounds are antiferromagnets with Neel temperatures between 23 K for Tb{sub 3}Cu{sub 4}Ge{sub 4} and 5.9 K for Er{sub 3}Cu{sub 4}Sn{sub 4}. For Tb{sub 3}Cu{sub 4}Ge{sub 4}, Er{sub 3}Cu{sub 4}Ge{sub 4} and Er{sub 3}Cu{sub 4}Sn{sub 4}, additional phase transitions are observed below the Neel temperature. The neutron-diffraction data indicate that the magnetic moments are localised only on the rare earth atoms. The moments located at different crystallographic sites have different values and order at different temperatures.

  16. Energy dependence of transverse momentum fluctuations in Pb+Pb collisions at the CERN Super Proton Synchrotron (SPS) at 20A to 158A GeV

    Energy Technology Data Exchange (ETDEWEB)

    NA49 Collaboration; Anticic, T.

    2009-04-15

    Results are presented on event-by-event fluctuations of transverse momenta p{sub T} in central Pb+Pb interactions at 20A, 30A, 40A, 80A, and 158A GeV. The analysis was performed for charged particles at forward center-of-mass rapidity (1.1 < y*{sub {pi}} < 2.6). Three fluctuation measures were studied: the distribution of average transverse momentum M(p{sub T}) in the event, the {phi}{sub p{sub T}} fluctuation measure, and two-particle transverse momentum correlations. Fluctuations of p{sub T} are small and show no significant energy dependence in the energy range of the CERN Super Proton Synchrotron. Results are compared with QCD-inspired predictions for the critical point, and with the UrQMD model. Transverse momentum fluctuations, similar to multiplicity fluctuations, do not show the increase expected for freeze-out near the critical point of QCD.

  17. The pure rotational spectra of the open-shell diatomic molecules PbI and SnI

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Corey J., E-mail: cje8@le.ac.uk, E-mail: nick.walker@newcastle.ac.uk; Needham, Lisa-Maria E. [Department of Chemistry, University of Leicester, Leicester LE1 7RH (United Kingdom); Walker, Nicholas R., E-mail: cje8@le.ac.uk, E-mail: nick.walker@newcastle.ac.uk; Köckert, Hansjochen; Zaleski, Daniel P.; Stephens, Susanna L. [School of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom)

    2015-12-28

    Pure rotational spectra of the ground electronic states of lead monoiodide and tin monoiodide have been measured using a chirped pulsed Fourier transform microwave spectrometer over the 7-18.5 GHz region for the first time. Each of PbI and SnI has a X {sup 2}Π{sub 1/2} ground electronic state and may have a hyperfine structure that aids the determination of the electron electric dipole moment. For each species, pure rotational transitions of a number of different isotopologues and their excited vibrational states have been assigned and fitted. A multi-isotopologue Dunham-type analysis was carried out on both species producing values for Y{sub 01}, Y{sub 02}, Y{sub 11}, and Y{sub 21}, along with Λ-doubling constants, magnetic hyperfine constants and nuclear quadrupole coupling constants. The Born-Oppenheimer breakdown parameters for Pb have been evaluated and the parameter rationalized in terms of finite nuclear field effects. Analysis of the bond lengths and hyperfine interaction indicates that the bonding in both PbI and SnI is ionic in nature. Equilibrium bond lengths have been evaluated for both species.

  18. J/$\\psi$ azimuthal anisotropy relative to the reaction plane in Pb-Pb collisions at 158 GeV per nucleon

    CERN Document Server

    Prino, F; Alexa, C; Arnaldi, R; Atayan, M; Beolè, S; Boldea, V; Bordalo, P; Borges, G; Castanier, C; Castor, J; Chaurand, B; Cheynis, B; Chiavassa, E; Cicalo, C; Comets, M P; Constantinescu, S; Cortese, P; De Falco, A; De Marco, N; Dellacasa, G; Devaux, A; Dita, S; Fargeix, J; Force, P; Gallio, M; Gerschel, C; Giubellino, P; Golubeva, M B; Grigoryan, A A; Grigoryan, S; Guber, F F; Guichard, A; Gulkanyan, H; Idzik, M; Jouan, D; Karavicheva, T L; Kluberg, L; Kurepin, A B; Le Bornec, Y; Lourenço, C; Mac Cormick, M; Marzari-Chiesa, A; Masera, M; Masoni, A; Monteno, M; Musso, A; Petiau, P; Piccotti, A; Pizzi, J R; Puddu, G; Quintans, C; Ramello, L; Ramos, S; Riccati, L; Santos, H; Saturnini, P; Scomparin, E; Serci, S; Shahoyan, R; Sigaudo, F; Sitta, M; Sonderegger, P; Tarrago, X; Topilskaya, N S; Usai, G L; Vercellin, E; Villatte, L; Willis, N; Wu, T

    2009-01-01

    The J/$\\psi$ azimuthal distribution relative to the reaction plane has been measured by the NA50 experiment in Pb-Pb collisions at 158 GeV/nucleon. Various physical mechanisms related to charmonium dissociation in the medium created in the heavy ion collision are expected to introduce an anisotropy in the azimuthal distribution of the observed J/$\\psi$ mesons at SPS energies. Hence, the measurement of J/$\\psi$ elliptic anisotropy, quantified by the Fourier coefficient v$_2$ of the J/$\\psi$ azimuthal distribution relative to the reaction plane, is an important tool to constrain theoretical models aimed at explaining the anomalous J/$\\psi$ suppression observed in Pb-Pb collisions. We present the measured J/$\\psi$ yields in different bins of azimuthal angle relative to the reaction plane, as well as the resulting values of the Fourier coefficient v$_{2}$ as a function of the collision centrality and of the J/$\\psi$ transverse momentum. The reaction plane has been estimated from the azimuthal distribution of the ...

  19. Effects of uniaxial strain on electron effective mass and tunneling capability of direct gap Ge{sub 1−x}Sn{sub x} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lei; Liang, Renrong, E-mail: liangrr@tsinghua.edu.cn; Wang, Jing; Xu, Jun [Tsinghua National Laboratory for Information Science and Technology, Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

    2016-01-15

    Direct gap Ge{sub 1−x}Sn{sub x} alloys under [100] and [110] uniaxial strain are comprehensively investigated by theoretical calculations using the nonlocal empirical pseudopotential method (EPM). It is shown that [100] uniaxial tensile strain aids indirect-to-direct gap transition in Ge{sub 1−x}Sn{sub x} alloys. The Γ electron effective mass along the optimal direction under [110] uniaxial strain is smaller than those under [100] uniaxial strain and (001) biaxial strain. Additionally, the direct tunneling gap is smallest along the strain-perpendicular direction under [110] uniaxial tensile strain, resulting in a maximum direct band-to-band tunneling generation rate. An optimal [110] uniaxial tensile strain is favorable for high-performance direct gap Ge{sub 1−x}Sn{sub x} electronic devices.

  20. Thermal stability and relaxation mechanisms in compressively strained Ge0.94Sn0.06 thin films grown by molecular beam epitaxy

    Science.gov (United States)

    Fleischmann, C.; Lieten, R. R.; Hermann, P.; Hönicke, P.; Beckhoff, B.; Seidel, F.; Richard, O.; Bender, H.; Shimura, Y.; Zaima, S.; Uchida, N.; Temst, K.; Vandervorst, W.; Vantomme, A.

    2016-08-01

    Strained Ge1-xSnx thin films have recently attracted a lot of attention as promising high mobility or light emitting materials for future micro- and optoelectronic devices. While they can be grown nowadays with high crystal quality, the mechanism by which strain energy is relieved upon thermal treatments remains speculative. To this end, we investigated the evolution (and the interplay) of composition, strain, and morphology of strained Ge0.94Sn0.06 films with temperature. We observed a diffusion-driven formation of Sn-enriched islands (and their self-organization) as well as surface depressions (pits), resulting in phase separation and (local) reduction in strain energy, respectively. Remarkably, these compositional and morphological instabilities were found to be the dominating mechanisms to relieve energy, implying that the relaxation via misfit generation and propagation is not intrinsic to compressively strained Ge0.94Sn0.06 films grown by molecular beam epitaxy.

  1. Anomalous $J/\\psi$ suppression in 158 GeV/c Pb-Pb collisions at the CERN SPS

    CERN Document Server

    Abreu, M C; Alexa, C; Astruc, J; Baglin, C; Baldit, A; Bellaiche, F G; Bedjidian, Marc; Beolè, S; Borhani, A; Boldea, V; Bonazzola, G C; Bordalo, P; Bussière, A; Capony, V; Castor, J I; Cerú, M; Chambon, T; Chaurand, B; Chevrot, I; Cheynis, B; Chiavassa, E; Cicalò, C; Constantinescu, S; Dabrowski, W; De Falco, A; Dellacasa, G; De Marco, N; Devaux, A; Dita, S; Drapier, O; Espagnon, B; Fargeix, J; Fleuret, F; Force, P; Gallio, M; Gavrilov, Yu K; Gerschel, C; Giubellino, P; Golubeva, M B; Gonin, M; Gorodetzky, P; Grossiord, J Y; Guaita, P; Guber, F F; Guichard, A; Haroutunian, R; Idzik, M; Jouan, D; Karavitcheva, T L; Kossakowski, R; Kluberg, L; Kurepin, A B; Le Bornec, Y; Landaud, G; Lourenço, C; Luquin, Lionel; Macciotta, P; Ohlsson-Malek, F; Marzari-Chiesa, A; Masera, M; Masoni, A; Mourgues, S; Musso, A; Petiau, P; Prado da Silva, W L; Piccotti, A; Pizzi, J R; Puddu, G; Racca, C; Ramello, L; Ramos, S; Rato-Mendes, P; Riccati, L; Romana, A; Sartori, S M; Saturnini, P; Scomparin, E; Shao, Ian R; Silva, S; Serci, S; Sonderegger, P; Tarrago, X; Temnikov, P P; Topilskaya, N S; Usai, G L; Vercellin, Ermanno; Willis, N

    1997-01-01

    Heavy ion production of J/ psi mesons has been studied at CERN for a decade, in search for the Quark-Gluon Plasma predicted by lattice QCD. The suppression observed very early in O-Cu, O-U and S-U reactions has been shown to be eventually explained by nuclear absorption, and follow the same exponential behavior as the proton- nucleus reactions. The new Pb-Pb data deviate from this behavior very strongly, indicating the onset of a new regime in J/ psi suppression. (9 refs).

  2. Origin of the granites and related Sn and Pb-Zn polymetallic ore deposits in the Pengshan district, Jiangxi Province, South China: constraints from geochronology, geochemistry, mineral chemistry, and Sr-Nd-Hf-Pb-S isotopes

    Science.gov (United States)

    Xu, Bin; Jiang, Shao-Yong; Luo, Lan; Zhao, Kui-Dong; Ma, Liang

    2016-05-01

    The Pengshan Sn and Pb-Zn polymetallic deposits are located in the south margin of the Jiujiang-Ruichang (Jiurui) district of the Middle-Lower Yangtze River Metallogenic Belt in South China. Four large deposits include Huangjinwa, Zengjialong, Jianfengpo, and Zhangshiba, the former three are Sn-dominant deposits which occur as stratiform orebodies in the contact zones of the Pengshan granites and within the country rock strata, whereas Zhangshiba consists of stratiform Pb-Zn orebodies within the Precambrian metasedimentary strata. In this study, we present results on zircon U-Pb ages, major and trace elements, and mineral chemistry as well as Sr-Nd-Hf isotope data of the granites, Pb and S isotopes of both the Sn-dominant and Pb-Zn dominant deposits, and U-Pb dating of cassiterite from the Pengshan district. SHRIMP and LA-ICP-MS zircon U-Pb dating shows that the Pengshan granites were emplaced in the Early Cretaceous (129-128 Ma), which is in good agreement with the U-Pb dating (130-128 Ma) of cassiterite from the Jianfengpo Sn deposit. The Pengshan granites consist mainly of weakly peraluminous highly fractionated I-type affinity granitic rocks. Detailed elemental and isotopic data suggest that the granites formed by partial melting of Mesoproterozoic metamorphic basement materials with minor input of mantle-derived melts. The mineral chemistry of biotite demonstrates that the Pengshan granitic magma had a low oxygen fugacity, thereby precluding the tin dominantly partitioning into the rock-forming silicate minerals and favoring accumulation in the exsolved residual liquid during magma crystallization stages. Sulfur isotopes show a relatively heavy sulfur isotopic composition from 5.8 to 17.6 ‰, and no difference for sulfur isotopes between the Sn deposits (5.8-13.4 ‰, Huangjinwa, Zengjialong, Jianfengpo) and the Pb-Zn deposit (mostly 7.1-13.0 ‰, except for one 17.6 ‰, Zhangshiba). The sulfur isotope data of pyrite from the host sedimentary rocks show

  3. Origin of the granites and related Sn and Pb-Zn polymetallic ore deposits in the Pengshan district, Jiangxi Province, South China: constraints from geochronology, geochemistry, mineral chemistry, and Sr-Nd-Hf-Pb-S isotopes

    Science.gov (United States)

    Xu, Bin; Jiang, Shao-Yong; Luo, Lan; Zhao, Kui-Dong; Ma, Liang

    2017-03-01

    The Pengshan Sn and Pb-Zn polymetallic deposits are located in the south margin of the Jiujiang-Ruichang (Jiurui) district of the Middle-Lower Yangtze River Metallogenic Belt in South China. Four large deposits include Huangjinwa, Zengjialong, Jianfengpo, and Zhangshiba, the former three are Sn-dominant deposits which occur as stratiform orebodies in the contact zones of the Pengshan granites and within the country rock strata, whereas Zhangshiba consists of stratiform Pb-Zn orebodies within the Precambrian metasedimentary strata. In this study, we present results on zircon U-Pb ages, major and trace elements, and mineral chemistry as well as Sr-Nd-Hf isotope data of the granites, Pb and S isotopes of both the Sn-dominant and Pb-Zn dominant deposits, and U-Pb dating of cassiterite from the Pengshan district. SHRIMP and LA-ICP-MS zircon U-Pb dating shows that the Pengshan granites were emplaced in the Early Cretaceous (129-128 Ma), which is in good agreement with the U-Pb dating (130-128 Ma) of cassiterite from the Jianfengpo Sn deposit. The Pengshan granites consist mainly of weakly peraluminous highly fractionated I-type affinity granitic rocks. Detailed elemental and isotopic data suggest that the granites formed by partial melting of Mesoproterozoic metamorphic basement materials with minor input of mantle-derived melts. The mineral chemistry of biotite demonstrates that the Pengshan granitic magma had a low oxygen fugacity, thereby precluding the tin dominantly partitioning into the rock-forming silicate minerals and favoring accumulation in the exsolved residual liquid during magma crystallization stages. Sulfur isotopes show a relatively heavy sulfur isotopic composition from 5.8 to 17.6 ‰, and no difference for sulfur isotopes between the Sn deposits (5.8-13.4 ‰, Huangjinwa, Zengjialong, Jianfengpo) and the Pb-Zn deposit (mostly 7.1-13.0 ‰, except for one 17.6 ‰, Zhangshiba). The sulfur isotope data of pyrite from the host sedimentary rocks show

  4. Pb(Zr,Sn,Ti)O3反铁电-铁电陶瓷热释电谱

    Institute of Scientific and Technical Information of China (English)

    冯玉军; 徐卓; 杨同青; 姚熹

    2000-01-01

    改性Pb(Zr,Sn,Ti)O3反铁电-铁电陶瓷存在着多种晶体结构, 随着温度变化会发生相变而影响材料的性能. 研究了铌改性Pb(Zr,Sn,Ti)O3反铁电-铁电陶瓷温度诱导相变中的热释电效应. 结果表明, 温度诱导相变引起电荷突变形成尖锐的热释电峰, 热释电峰的形状和位置取决于相变的类型和温度. 组分和初相态变化导致的不同相态变化过程形成峰形和峰位不同的热释电谱. 热释电谱不仅可以显示极化强度随温度的变化情况而且可以测定出弱的次级转变, 如在介电温谱中难以观测的反铁电AFEA-AFEB、铁电FEL-FEH之间的相态转变在热释电谱中都有明显的热释电峰. 作为一种弱电测量方法, 热释电谱可以完整地反映Pb(Zr,Sn,Ti)O3反铁电-铁电材料相态随温度变化的情况.

  5. Theoretical study on photon-phonon coupling at (001)-(2 x 1) surfaces of Ge and {alpha}-Sn

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Sanchez, F.L. [Escuela de Ciencias, Universidad Autonoma ' ' Benito Juarez' ' de Oaxaca, Av. Universidad S/N, Ex-Hacienda de Cinco Senores, Ciudad Universitaria, Oaxaca de Juarez, Oax., 68120 (Mexico); Perez-Rodriguez, F. [Instituto de Fisica, Benemerita Universidad Autonoma de Puebla, Apdo. Post. J-48, Puebla, Pue. 72570 (Mexico)

    2011-06-15

    We present a study of the far-infrared reflectance anisotropy spectra for (001) surfaces of Ge and {alpha}-Sn in the (2 x 1) asymmetric dimer geometry, which exhibit a resonance structure associated with the excitation of surface phonon modes. We have employed a theoretical formalism, based on the adiabatic bond-charge model (ABCM), for computing the far-infrared reflectance anisotropy spectra. In comparison with previous theoretical results for silicon and diamond surfaces, the resonance structure in the reflectance anisotropy spectrum for Ge(001)-(2 x 1) turns out to be similar to that observed in the spectrum for the Si(001)-(2 x 1) surface, whereas the spectrum for {alpha}-Sn(001)-(2 x 1) surface is noticeably different from the others. We have established a trend of far-infrared reflectance anisotropy spectra for IV(001) surfaces: the weaker dimer strength, the stronger resonances of low-frequency surface phonons. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Tuning Bandgap of p-Type Cu2Zn(Sn, Ge)(S, Se)4 Semiconductor Thin Films via Aqueous Polymer-Assisted Deposition.

    Science.gov (United States)

    Yi, Qinghua; Wu, Jiang; Zhao, Jie; Wang, Hao; Hu, Jiapeng; Dai, Xiao; Zou, Guifu

    2017-01-18

    Bandgap engineering of kesterite Cu2Zn(Sn, Ge)(S, Se)4 with well-controlled stoichiometric composition plays a critical role in sustainable inorganic photovoltaics. Herein, a cost-effective and reproducible aqueous solution-based polymer-assisted deposition approach is developed to grow p-type Cu2Zn(Sn, Ge)(S, Se)4 thin films with tunable bandgap. The bandgap of Cu2Zn(Sn, Ge)(S, Se)4 thin films can be tuned within the range 1.05-1.95 eV using the aqueous polymer-assisted deposition by accurately controlling the elemental compositions. One of the as-grown Cu2Zn(Sn, Ge)(S, Se)4 thin films exhibits a hall coefficient of +137 cm(3)/C. The resistivity, concentration and carrier mobility of the Cu2ZnSn(S, Se)4 thin film are 3.17 ohm·cm, 4.5 × 10(16) cm(-3), and 43 cm(2)/(V·S) at room temperature, respectively. Moreover, the Cu2ZnSn(S, Se)4 thin film when used as an active layer in a solar cell leads to a power conversion efficiency of 3.55%. The facile growth of Cu2Zn(Sn, Ge)(S, Se)4 thin films in an aqueous system, instead of organic solvents, provides great promise as an environmental-friendly platform to fabricate a variety of single/multi metal chalcogenides for the thin film industry and solution-processed photovoltaic devices.

  7. Electronic structure and thermoelectric properties of (Mg2X)2 / (Mg2Y)2 (X, Y = Si, Ge, Sn) superlattices from first-principle calculations

    Science.gov (United States)

    Guo, San-Dong

    2016-05-01

    To identify thermoelectric materials containing abundant, low-cost and non-toxic elements, we have studied the electronic structures and thermoelectric properties of (Mg2X)2/ (Mg2Y)2 (X, Y = Si, Ge, Sn) superlattices with state-of-the-art first-principles calculations using a modified Becke and Johnson (mBJ) exchange potential. Our results show that (Mg2Ge)2/ (Mg2Sn)2 and (Mg2Si)2/ (Mg2Sn)2 are semi-metals using mBJ plus spin-orbit coupling (mBJ + SOC), while (Mg2Si)2/ (Mg2Ge)2 is predicted to be a direct-gap semiconductor with a mBJ gap value of 0.46 eV and mBJ + SOC gap value of 0.44 eV. Thermoelectric properties are predicted by through solving the Boltzmann transport equations within the constant scattering time approximation. It is found that (Mg2Si)2/ (Mg2Ge)2 has a larger Seebeck coefficient and power factor than (Mg2Ge)2/ (Mg2Sn)2 and (Mg2Si)2/ (Mg2Sn)2 for both p-type and n-type doping. The detrimental influence of SOC on the power factor of p-type (Mg2X)2/ (Mg2Y)2 (X, Y = Si, Ge, Sn) is analyzed as a function of the carrier concentration, but there is a negligible SOC effect for n-type. These results can be explained by the influence of SOC on their valence and conduction bands near the Fermi level.

  8. Excitation of giant monopole resonance in {sup 208}Pb and {sup 116}Sn using inelastic deuteron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Patel, D.; Garg, U. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame, IN 46556 (United States); Itoh, M. [Cyclotron and Radioisotope Center, Tohoku University, Sendai 980-8578 (Japan); Akimune, H. [Department of Physics, Konan University, Kobe 568-8501 (Japan); Berg, G.P.A. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame, IN 46556 (United States); Fujiwara, M. [Research Center for Nuclear Physics, Osaka University, Osaka 567-0047 (Japan); Harakeh, M.N. [Kernfysisch Versneller Instituut, University of Groningen, 9747 AA Groningen (Netherlands); GANIL, CEA/DSM-CNRS/IN2P3, 14076 Caen (France); Iwamoto, C. [Department of Physics, Konan University, Kobe 568-8501 (Japan); Kawabata, T. [Division of Physics and Astronomy, Kyoto University, Kyoto 606-8502 (Japan); Kawase, K. [Japan Atomic Energy Agency, Kyoto 619-0215 (Japan); Matta, J.T. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame, IN 46556 (United States); Murakami, T. [Division of Physics and Astronomy, Kyoto University, Kyoto 606-8502 (Japan); Okamoto, A. [Department of Physics, Konan University, Kobe 568-8501 (Japan); Sako, T. [Japan Atomic Energy Agency, Kyoto 619-0215 (Japan); Schlax, K.W. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Takahashi, F. [Research Center for Nuclear Physics, Osaka University, Osaka 567-0047 (Japan); White, M. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Yosoi, M. [Research Center for Nuclear Physics, Osaka University, Osaka 567-0047 (Japan)

    2014-07-30

    The excitation of the isoscalar giant monopole resonance (ISGMR) in {sup 208}Pb and {sup 116}Sn has been investigated using small-angle (including 0°) inelastic scattering of 100 MeV/u deuteron and multipole-decomposition analysis (MDA). The extracted strength distributions agree well with those from inelastic scattering of 100 MeV/u α particles. These measurements establish deuteron inelastic scattering at E{sub d}∼100 MeV/u as a suitable probe for extraction of the ISGMR strength with MDA, making feasible the investigation of this resonance in radioactive isotopes in inverse kinematics.

  9. Laser ablative fluxless soldering (LAFS): 60Sn-40Pb solder wettability tests on laser cleaned OFHC copper substrates

    Energy Technology Data Exchange (ETDEWEB)

    Peebles, H. C.; Keicher, D. M.; Hosking, F. M.; Hlava, P. F.; Creager, N. A.

    1991-01-01

    OFHC copper substrates, cleaned by laser ablation under argon and helium gas, were tested for solder wettability by 60Sn-40Pb using an area-of-spread method. The wettability of copper surfaces cleaned under both argon and helium gas was found to equal or exceed the wettability obtained on this surface in air using a standard RMA flux. The area of spread on copper substrates cleaned under helium was eight times larger than the area of spread of substrates cleaned under argon. The enhanced spreading observed on the substrates cleaned under helium gas was found to be due to surface roughness. 11 refs., 8 figs., 2 tabs.

  10. Velocity-Map Imaging Spectroscopy of the Ge^-, Sn^-, and Pb^- Negative Ions

    Science.gov (United States)

    Chartkunchand, Kiattichart; Carpenter, Kyle; Davis, Vernon; Neill, Paul; Thompson, Jeffrey; Covington, Aaron

    2012-06-01

    Photoelectrons ejected from collisions between laser-produced photons and fast-moving beams of negaitve ions have been studied using the technique of Velocity-Map Imaging (VMI) spectroscopy. Digital images produced by the VMI spectrometer have been used to determine photoelectron kinetic energy spectra, as well as photoelectron angular distributions for select isoelectronic Group 14 anions. Analysis of these data are helping to clarify detailed structural properties of these ions with increasing Z and is providing dynamical information on the photon-ion collision systems.

  11. Electronic structure and magnetism of new ilmenite compounds for spintronic devices: FeBO{sub 3} (B = Ti, Hf, Zr, Si, Ge, Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, R.A.P. [Department of Chemistry, State University of Ponta Grossa, Av. General Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR (Brazil); Camilo, A. [Department of Physics, State University of Ponta Grossa, Av. General Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR (Brazil); Lazaro, S.R. de, E-mail: srlazaro@uepg.br [Department of Chemistry, State University of Ponta Grossa, Av. General Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR (Brazil)

    2015-11-15

    First-principles calculations were performed in the framework of Density Functional Theory (DFT) within hybrid functional (B3LYP) to study the electronic structure and magnetic properties of new ilmenite FeBO{sub 3} (B=Ti, Hf, Zr, Si, Ge, Sn) materials. In particular, the magnetic exchange interaction between Fe{sup 2+} layers is dependent on the interlayer distance and it can be controlled by ionic radius of B-site cation. Thus, Fe(Ti, Si, Ge)O{sub 3} are antiferromagnetic materials, while Fe(Zr, Hf, Sn)O{sub 3} are ferromagnetic. We also argue that antiferromagnetic materials and FeZrO{sub 3} are convectional semiconductors, whereas FeHfO{sub 3} and FeSnO{sub 3} exhibit intrinsic half-metallic behavior, making them promising candidates for spintronic devices. - Highlights: • We study electronic structure and magnetism of new FeBO{sub 3} (B=Ti, Hf, Zr, Si, Ge, Sn) ilmenite materials. • We found that magnetic ordering of Fe-based ilmenite materials can be controlled by size of B-site cation. • Fe(Ti, Zr, Si, Ge)O{sub 3} are convectional semiconductors. • FeHfO{sub 3} and FeSnO{sub 3} exhibit intrinsic half-metallic behavior with potential application for spintronic devices.

  12. Source radii at target rapidity from two-proton and two-deuteron correlations in central Pb+Pb collisions at 158 A GeV

    CERN Document Server

    Aggarwal, M M; Angelis, A.L.S.; Antonenko, V.; Arefiev, V.; Astakhov, V.; Avdeitchikov, V.; Awes, T.C.; Baba, P.V.K.S.; Badyal, S.K.; Bathe, S.; Batiounia, B.; Bernier, T.; Bhalla, K.B.; Bhatia, V.S.; Blume, C.; Bucher, D.; Busching, H.; Carlen, L.; Chattopadhyay, S.; Decowski, M.P.; Delagrange, H.; Donni, P.; Dutta Majumdar, M.R.; El Chenawi, K.; Dubey, A.K.; Enosawa, K.; Fokin, S.; Frolov, V.; Ganti, M.S.; Garpman, S.; Gavrishchuk, O.; Geurts, F.J.M.; Ghosh, T.K.; Glasow, R.; Guskov, B.; Gustafsson, H.A.; Gutbrod, H.H.; Hrivnacova, I.; Ippolitov, M.; Kalechofsky, H.; Kamermans, R.; Karadjev, K.; Karpio, K.; Kolb, B.W.; Kosarev, I.; Koutcheryaev, I.; Kugler, A.; Kulinich, P.; Kurata, M.; Lebedev, A.; Liu, H.; Lohner, H.; Luquin, L.; Mahapatra, D.P.; Manko, V.; Martin, M.; Martinez, G.; Maximov, A.; Miake, Y.; Mishra, G.C.; Mohanty, B.; Mora, M.-J.; Morrison, D.; Moukhanova, T.; Mukhopadhyay, D.S.; Naef, H.; Nandi, B.K.; Nayak, S.K.; Nayak, T.K.; Nianine, A.; Nikitine, V.; Nikolaev, S.; Nilsson, P.; Nishimura, S.; Nomokonov, P.; Nystrand, J.; Oskarsson, A.; Otterlund, I.; Pavliouk, S.; Peitzmann, T.; Peressounko, D.; Petracek, V.; Petracek, V.; Pinanaud, W.; Plasil, F.; Purschke, M.L.; Rak, J.; Raniwala, R.; Raniwala, S.; Rao, N.K.; Retiere, F.; Reygers, K.; Roland, G.; Rosselet, L.; Roufanov, I.; Roy, C.; Rubio, J.M.; Sambyal, S.S.; Santo, R.; Sato, S.; Schlagheck, H.; Schmidt, H.-R.; Schutz, Y.; Shabratova, G.; Shah, T.H.; Sibiriak, I.; Siemiarczuk, T.; Silvermyr, D.; Sinha, B.C.; Slavine, N.; Soderstrom, K.; Sood, G.; Sorensen, S.P.; Stankus, P.; Stefanek, G.; Steinberg, P.; Stenlund, E.; Sumbera, M.; Svensson, T.; Tsvetkov, A.; Tykarski, L.; van de Pijll, E.C.; van Eijndhoven, N.; van Nieuwenhuizen, G.J.; Vinogradov, A.; Viyogi, Y.P.; Vodopianov, A.; Voros, S.; Wyslouch, B.; Young, G.R.

    2007-01-01

    Two-proton and two-deuteron correlations have been studied in the target fragmentation region of central Pb+Pb collisions at 158 A GeV. Protons and deuterons were measured with the Plastic Ball spectrometer of the WA98 experiment at the CERN SPS. The results of one-dimensional and multi-dimensional analyses using both the Bertsch-Pratt and Yano-Koonin-Podgoretsky parameterizations of the two-particle correlation functions are presented. The proton source exhibits a volume emission, while the deuteron source, with small outward radius, appears opaque. Both proton and deuteron sources have cross-terms R_{ol}^2 and longitudinal velocities beta consistent with zero, indicating a boost-invariant expansion. The invariant radius parameter R follows an approximate A/sqrt{m} scaling while the longitudinal and transverse radii, R_{L} and R_{T}, scale approximately as A/sqrt{m_{T}} with A ~ 3 fm GeV^{1/2} in both cases.

  13. Kaon and pion production in centrality selected minimum bias Pb+Pb collisions at 40 and 158A.GeV

    CERN Document Server

    Dinkelaker, Peter

    2009-01-01

    Results on charged kaon and negatively charged pion production and spectra for centrality selected Pb+Pb mininimum bias events at 40 and 158A GeV have been presented in this thesis. All analysis are based on data taken by the NA49 experiment at the accelerator Super Proton Synchrotron (SPS) at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland. The kaon results are based on an analysis of the mean energy loss of the charged particles traversing the detector gas of the time projection chambers (TPCs). The pion results are from an analysis of all negatively charged particles h- corrected for contributions from particle decays and secondary interactions. For the dE/dx analysis of charged kaons, main TPC tracks with a total momentum between 4 and 50 GeV have been analyzed in logarithmic momentum log(p) and transverse momentum pt bins. The resulting dE/dx spectra have been fitted by the sum of 5 Gaussians, one for each main particle type (electrons, pions, kaons, pro...

  14. {phi}, {rho} and {omega} meson production in the collisions d-C, d-U, S-U at 200 GeV/nucleon and Pb-Pb at 158 GeV/nucleon; Production de mesons {phi}, {rho} et {omega} dans les collisions d-C,d-U, S-U a 200 GeV/nucleon et Pb-Pb a 158 GeV/nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Astruc, J. [Institut National de Physique Nucleaire et de Physique des Particules (India2P3), 75 - Paris (France)

    1997-07-09

    Experiments NA38 and NA50, at the CERN-SPS, study the muon production in ultrarelativistic heavy ion collisions. They are dedicated to the measurement of the {phi}, {omega}, {rho} and J/{psi} production rates. The change of the vector meson production when using heavy ion projectiles, may be a signature for quark gluon plasma (QGP) phase transition. This new form of matter could be produced at the high temperature reached in this collisions. Among others, the anomalous increase of strangeness production could be a signature of the QGP formation. In this thesis, we present the studies of the {phi} strange meson production with respect to that of non-strange mesons, {rho} and {omega}, in d-C, d-U and S-U collisions at 200 GeV/c per nucleon and Pb-Pb at 158 GeV/c per nucleon in different transverse mass bins of the muon pairs. The comparison between the {phi} and the {rho} + {omega} production, as well as the mass continuum, shows an increase of the {phi} production with respect to that of the {rho} + {omega}, with the increasing size of the system and with increasing centrality in S-U and Pb-Pb collisions. The cross section studies in the different systems show the change of the behaviour of vector meson production when going from deuterium-nucleus to nucleus-nucleus interactions. Besides, a general evolution of the {rho} + {omega} and continuum production is observed, on which an additional increase for {phi} is superimposed. These evolutions are even more coherent between the S-U and Pb-Pb collisions and manifest themselves by an increase of the inverse slopes of the transverse mass spectra between d-C and S-U. A atypical behaviour of the {phi}/{omega} ratio in the in the most central Pb-Pb collisions for which the same experiment has made evident a abnormal suppression of J/{psi}, was also observed. (author) 61 refs.

  15. Magnetism, band gap and stability of half-metallic property for the quaternary Heusler alloys CoFeTiZ (Z = Si, Ge, Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.J. [Department of Physics, University of Science and Technology Beijing, 100083 Beijing (China); Liu, Z.H., E-mail: zhliu@ustb.edu.cn [Department of Physics, University of Science and Technology Beijing, 100083 Beijing (China); Li, G.T.; Ma, X.Q. [Department of Physics, University of Science and Technology Beijing, 100083 Beijing (China); Liu, G.D. [School of Material Science and Engineering, Hebei University of Technology, 300130 Tianjin (China)

    2014-12-15

    Highlights: • CoFeTiZ (Z = Si, Ge) have been predicted to be ferrimagnetism half-metallic alloys. • Effect of the sp element on the band gap and the half-metallicity have been analyzed. • The half-metallicity of these alloys shows good stability. - Abstract: The electronic structures and magnetic properties of quaternary Heusler alloys CoFeTiZ (Z = Si, Ge, Sn) have been studied using first-principles calculations. It has been found that CoFeTiSi and CoFeTiGe are half-metallic ferrimagnets, while CoFeTiSn is a quasi half-metallic ferrimagnet. The total moment in unit cell for CoFeTiZ (Z = Si, Ge, Sn) alloys follows the Slater–Pauling behavior with the total number of valence electrons minus 24. The origin of the magnetism, band gap, and the effect of atom Z on the band gap and the half-metallicity of the alloys have been discussed in detail. The half-metallic property for CoFeTiSi and CoFeTiGe can be retained when their lattice constants are changed in a large range. CoFeTiSn alloy can transform from a quasi half-metallic to a half-metallic alloy by employing a proper compression stress.

  16. GeP and (Ge{sub 1−x}Sn{sub x})(P{sub 1−y}Ge{sub y}) (x≈0.12, y≈0.05): Synthesis, structure, and properties of two-dimensional layered tetrel phosphides

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kathleen; Synnestvedt, Sarah; Bellard, Maverick; Kovnir, Kirill, E-mail: kkovnir@ucdavis.edu

    2015-04-15

    GeP and Sn-doped GeP were synthesized from elements in bismuth and tin flux, respectively. The layered crystal structures of these compounds were characterized by single crystal X-ray diffraction. Both phosphides crystallize in a GaTe structure type in the monoclinic space group C2/m (No. 12) with GeP: a=15.1948(7) Å, b=3.6337(2) Å, c=9.1941(4) Å, β=101.239(2)°; Ge{sub 0.93(3)}P{sub 0.95(1)}Sn{sub 0.12(3)}: a=15.284(9) Å, b=3.622(2) Å, c=9.207(5) Å, β=101.79(1)°. The crystal structure of GeP consists of 2-dimensional GeP layers held together by weak electron lone pair interactions between the phosphorus atoms that confine the layer. Each layer is built of Ge–Ge dumbbells surrounded by a distorted antiprism of phosphorus atoms. Sn-doped GeP has a similar structural motif, but with a significant degree of disorder emphasized by the splitting of all atomic positions. Resistivity measurements together with quantum-chemical calculations reveal semiconducting behavior for the investigated phosphides. - Graphical abstract: Layered phosphides GeP and Sn-doped GeP were synthesized from elements in bismuth and tin flux, respectively. The crystal structure of GeP consists of 2-dimensional GeP layers held together by weak electron lone pair interactions between the phosphorus atoms that confine the layer. Sn-doped GeP has a similar structural motif with a significant degree of disorder emphasized by the splitting of all atomic positions. Resistivity measurements together with quantum-chemical calculations reveal semiconducting behavior for the investigated phosphides. - Highlights: • GeP crystallizes in a layered crystal structure. • Doping of Sn into GeP causes large structural distortions. • GeP is narrow bandgap semiconductor. • Sn-doped GeP exhibits an order of magnitude higher resistivity due to disorder.

  17. Ge{sub 0.83}Sn{sub 0.17} p-channel metal-oxide-semiconductor field-effect transistors: Impact of sulfur passivation on gate stack quality

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Dian; Wang, Wei; Gong, Xiao, E-mail: elegong@nus.edu.sg, E-mail: yeo@ieee.org; Liang, Gengchiau; Yeo, Yee-Chia, E-mail: elegong@nus.edu.sg, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Zhang, Zheng; Pan, Jisheng [Institute of Material Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Tok, Eng-Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

    2016-01-14

    The effect of room temperature sulfur passivation of the surface of Ge{sub 0.83}Sn{sub 0.17} prior to high-k dielectric (HfO{sub 2}) deposition is investigated. X-ray photoelectron spectroscopy (XPS) was used to examine the chemical bonding at the interface of HfO{sub 2} and Ge{sub 0.83}Sn{sub 0.17}. Sulfur passivation is found to be effective in suppressing the formation of both Ge oxides and Sn oxides. A comparison of XPS results for sulfur-passivated and non-passivated Ge{sub 0.83}Sn{sub 0.17} samples shows that sulfur passivation of the GeSn surface could also suppress the surface segregation of Sn atoms. In addition, sulfur passivation reduces the interface trap density D{sub it} at the high-k dielectric/Ge{sub 0.83}Sn{sub 0.17} interface from the valence band edge to the midgap of Ge{sub 0.83}Sn{sub 0.17}, as compared with a non-passivated control. The impact of the improved D{sub it} is demonstrated in Ge{sub 0.83}Sn{sub 0.17} p-channel metal-oxide-semiconductor field-effect transistors (p-MOSFETs). Ge{sub 0.83}Sn{sub 0.17} p-MOSFETs with sulfur passivation show improved subthreshold swing S, intrinsic transconductance G{sub m,int}, and effective hole mobility μ{sub eff} as compared with the non-passivated control. At a high inversion carrier density N{sub inv} of 1 × 10{sup 13 }cm{sup −2}, sulfur passivation increases μ{sub eff} by 25% in Ge{sub 0.83}Sn{sub 0.17} p-MOSFETs.

  18. Deuteron and triton production in Pb+Pb collisions at 158 A centre dot GeV.

    CERN Document Server

    Hansen, A G; Bøggild, H; Boissevain, J G; Conin, L; Christiansen, P; Dodd, J; Erazmus, B; Esumi, S; Fabjan, Christian Wolfgang; Ferenc, D; Fields, D E; Franz, A; Gaardhøje, J J; Hansen, A G; Hansen, O; Hardtke, D; Hecke, H V; Holzer, E B; Humanic, T J; Hummel, P; Jacak, B V; Jayanti, R; Kaimi, K; Kaneta, M; Kohama, T; Kopytine, M; Leltchouk, M; Ljubicic, A; Lörstad, B; Martin, L; Maeda, N; Malina, R; Medvedev, A; Murray, M; Ohnishi, H; Paic, G; Pandey, S U; Piuz, François; Pluta, J; Polychronakos, V; Potekhin, M V; Poulard, G; Reichhold, D M; Sakaguchi, A; Simon-Gillo, J; Schmidt-Sørensen, J; Sondheim, W E; Sugitate, T; Sullivan, J P; Sumi, Y; Willis, W J; Wolf, K L; Xu, N; Zachary, D S

    1999-01-01

    NA44 has measured the invariant cross section of deuterons and tritons at non zero p sub t in 158 A centre dot GeV lead on lead collisions at CERN SPS. Normalized transverse mass spectra and coalescence parameters versus p sub t have been calculated showing a significant transverse flow. Radius parameters have been extracted using a simple thermal coalescence model. Results from RQMD+coalescence calculations are compared to the data.

  19. Centrality dependence of ?, baryon and antibaryon production in Pb + Pb collisions at 158 A GeV

    Science.gov (United States)

    Kabana, Sonia; NA52 Collaboration; Ambrosini, G.; Arsenescu, R.; Baglin, C.; Beringer, J.; Borer, K.; Bussière, A.; Dittus, F.; Elsener, K.; Gorodetzky, Ph; Guillaud, J. P.; Hess, P.; Kabana, S.; Klingenberg, R.; Lindén, T.; Lohmann, K. D.; Mommsen, R.; Moser, U.; Pretzl, K.; Schacher, J.; Stoffel, F.; Tuominiemi, J.; Weber, M.

    1999-02-01

    We present new results of the CERN experiment NA52 on the centrality dependence of img23.gif, img24.gif, p, d, p and d production yields near zero transverse momentum and at several rapidities, from 64 img25.gif to 4 img25.gif of the total Pb + Pb cross section. Baryon yields increase nearly linearly and img24.gif yields faster than linearly with the number of participating nucleons img28.gif. The antibaryon yields increase less than linearly with img28.gif, indicating absorption. The centrality and rapidity dependence of the img30.gif ratio indicates Coulomb interaction of the pions with the projectile spectator protons. Within the framework of a coalescence model the radius of the particle source has been estimated from the ratios img31.gif and d /¯ img32.gif. The source radii are similar for matter and antimatter and are found to increase with img33.gif.

  20. The crystal structure of franckeite, Pb21.7Sn9.3Fe4.0Sb8.1S56.9

    DEFF Research Database (Denmark)

    Makovicky, Emil; Petricek, Vaclav; Dusek, Michal

    2011-01-01

    The layer-like crystal structure of franckeite from the mine of San José, Bolivia, exhibits a pronounced one-dimensional transversal wave-like modulation and a non-commensurate layer match in two dimensions. It consists of alternating pseudohexagonal (H) layers and pseudotetragonal (Q) slabs...... was refined as Pb0.74(Sn,Sb)0.26, whereas that of cations, which are adjacent to the interspace with lone electron pairs, with a configuration analogous to that observed in orthorhombic SnS, corresponds to (Sn,Sb)0.73Pb0.27. Iron is dispersed over the octahedral Sn4+ sites in the H layer. Transversal...

  1. Properties of heavily impurity-doped PbSnTe liquid-phase epitaxial layers grown by the temperature difference method under controlled Te vapor pressure

    Science.gov (United States)

    Yasuda, Arata; Takahashi, Yatsuhiro; Suto, Ken; Nishizawa, Jun-ichi

    2017-07-01

    We propose the use of heavily impurity-doped Pb1-xSnxTe/PbTe epitaxial layers grown via the temperature difference method under controlled vapor pressure (TDM-CVP) liquid-phase epitaxy (LPE) for the preparation of IV-VI compounds for mid- to far-infrared optical device applications. A flat surface morphology and the distribution of a constant Sn concentration for 0.05 ≤ x ≤ 0.33 were observed in the epitaxial layers using electron-probe microanalysis. The segregation coefficient of Sn in Pb1-xSnxTe grown via TDM-CVP LPE (Tg = 640 °C) was xSSn?xLSn = 0.28. The appearance of the Fermi level pinning and persistent photoconductivity effects in In-doped PbSnTe were also proposed; we estimated that the activation energies of these processes were 2.8 and 39.7 meV, respectively, based on the In-doped Pb1-xSnxTe carrier profile as a function of ambient temperature. In Hall mobility measurements, Sn was assumed to be a main scattering center in the Pb1-xSnxTe epitaxial crystals. The impurity effect was also observed in Pb1-xSnxTe epitaxial growth, similar to the effects observed for Tl-doped PbTe bulk crystals. We concluded that the heavily doped Pb1-xSnxTe crystals grown via TDM-CVP LPE can be used to fabricate high-performance mid- to far-infrared optical devices.

  2. Pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} on amorphous dielectric layers towards monolithic 3D photonic integration

    Energy Technology Data Exchange (ETDEWEB)

    Li, Haofeng; Brouillet, Jeremy; Wang, Xiaoxin; Liu, Jifeng, E-mail: Jifeng.Liu@dartmouth.edu [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States)

    2014-11-17

    We demonstrate pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} crystallized on amorphous layers at <450 °C towards 3D Si photonic integration. We developed two approaches to seed the lateral single crystal growth: (1) utilize the Gibbs-Thomson eutectic temperature depression at the tip of an amorphous GeSn nanotaper for selective nucleation; (2) laser-induced nucleation at one end of a GeSn strip. Either way, the crystallized Ge{sub 0.89}Sn{sub 0.11} is dominated by a single grain >18 μm long that forms optoelectronically benign twin boundaries with others grains. These pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} patterns are suitable for monolithic 3D integration of active photonic devices on Si.

  3. Unexpected superconductivity at nanoscale junctions made on the topological crystalline insulator Pb0.6Sn0.4Te

    Science.gov (United States)

    Das, Shekhar; Aggarwal, Leena; Roychowdhury, Subhajit; Aslam, Mohammad; Gayen, Sirshendu; Biswas, Kanishka; Sheet, Goutam

    2016-09-01

    Discovery of exotic phases of matter from the topologically non-trivial systems not only makes the research on topological materials more interesting but also enriches our understanding of the fascinating physics of such materials. Pb0.6Sn0.4Te was recently shown to be a topological crystalline insulator. Here, we show that by forming a mesoscopic point-contact using a normal non-superconducting elemental metal on the surface of Pb0.6Sn0.4Te, a superconducting phase is created locally in a confined region under the point-contact. This happens when the bulk of the sample remains to be non-superconducting, and the superconducting phase emerges as a nano-droplet under the point-contact. The superconducting phase shows a high transition temperature Tc that varies for different point-contacts and falls in a range between 3.7 K and 6.5 K. Therefore, this Letter presents the discovery of a superconducting phase on the surface of a topological crystalline insulator, and the discovery is expected to shed light on the mechanism of induced superconductivity in topologically non-trivial systems in general.

  4. New results from NA52 on particle production in Pb-Pb collisions at 158 A GeV/c

    Science.gov (United States)

    Arsenescu, R.; NA52 Collaboration; Ambrosini, G.; Arsenescu, R.; Baglin, C.; Beringer, J.; Bohm, C.; Borer, K.; Bussière, A.; Dittus, F.; Elsener, K.; Gorodetsky, Ph.; Guillaud, J. P.; Hess, P.; Kabana, S.; Klingenberg, R.; Lindén, T.; Lohmann, K. D.; Mommsen, R.; Moser, U.; Pretzl, K.; Schacher, J.; Selldén, B.; Stoffel, F.; Tuominiemi, J.; Weber, M.; Zhang, Q. P.

    1999-02-01

    We are presenting new results on and production in minimum bias lead-lead collisions at 158 A GeV/c. The measurements were performed at zero degree production angle and for a wide rapidity range. The analysis method used the full particle identification capabilities (time of flight, Cerenkov counters and hadronic calorimeter) of the spectrometer. We show K/ and ratios as a function of rapidity, as well as invariant particle production cross sections. As a particularity we observe near projectile rapidity an enhancement in the number of with respect to .

  5. Sn含量对PbSnO3-Pb(Mg1/3Nb2/3)O3-PbTiO3三元系压电陶瓷相结构和电性能的影响%Effect of Sn Content on the Phase Structure and Electrical Properties of PbSnO3-Pb(Mg1/3Nb2/3)O3-PbTiO3 Ternary Ceramics

    Institute of Scientific and Technical Information of China (English)

    王大伟; 赵全亮; 曹茂盛; 崔岩; ZHANG Shu-Jun

    2014-01-01

    采用两步钶铁矿前驱体工艺制备了PbSnO3-Pb(Mg1/3Nb2/3)O3-PbTiO3(PSn-PMN-PT)三元系压电陶瓷,研究了Sn含量的变化对PSn-PMN-PT三元系压电陶瓷结构和性能的影响.XRD结果表明,所选成分均处于三方相和四方相共存的准同型相界上,当Sn含量减少时,PSn-PMN-PT的XRD图谱基本没有发生变化,而当Sn含量增加时,在XRD图谱中逐渐出现烧绿石相.电性能研究表明,缺失少量Sn可以提高PSn-PMN-PT的压电、介电和铁电性能,减小损耗;而添加过量Sn明显损害其压电和铁电性能,增加损耗.缺失0.2mol%Sn的PSn-PMN-PT具有最佳的压电和铁电性能,d33:~530 pC/N,kp:~56.4%,Qm:~570,εr:~3070,tanδ:~0.32%,Pr:~28.9 μC/cm2,EC:~8 kV/cm.

  6. An Experimental study of neutral and charged particle fluctuations in Pb Pb collisions at 158-A-GeV

    CERN Document Server

    Sood, G

    2002-01-01

    Relativistic quantum field theory treats the vacuum as a medium, with bulk properties characterized by long-range order parameters. This has led to suggestions that regions of disoriented chiral condensate might be formed in high energy colli sion processes. In particular, the approximate chiral symmetry of QCD could lead to regions of vacuum which have chiral order parameters disoriented to directions which have non-zero isospin, i.e. disoriented chiral condensate. The prime accessible signature of DCC is the ratio of neutral to charged pions in a certain range of phase space which should exhibit non-statistical fluctuations. The WA98 experiment has been used to measure the charged and photon multiplicities in the central region of Pb+Pb collisions at the CERN SPS. PMD which has the ability to count photons is positioned at 21.5m from the target, covering the pseudorapidity range 2.9 region as compared to mixed events (I and II) and V+G events. To test the authenticity of the filtered events, these events a...

  7. Electronic, structural, and magnetic properties of the quaternary Heusler alloy NiCoMnZ (Z=Al, Ge, and Sn)

    Science.gov (United States)

    Halder, Madhumita; Mukadam, M. D.; Suresh, K. G.; Yusuf, S. M.

    2015-03-01

    The electronic, magnetic, and structural properties of the Heusler alloys NiCoMnZ (Z=Al, Ge, and Sn) have been investigated both theoretically and experimentally. NiCoMnGe and NiCoMnSn have ordered cubic Heusler structure (with a possible disorder between Ni and Co), while NiCoMnAl has a B2 type disordered Heusler structure with random occupancy between Mn and Al atom at their crystallographic sites. Electronic structure calculation shows that NiCoMnGe and NiCoMnSn are normal ferromagnets, whereas NiCoMnAl is nearly half metallic (~100% spin polarization) in nature with its magnetic moment close to an integer value following the Slater-Pauling rule. Ab-initio calculations show ~56% and ~60% spin polarization for NiCoMnGe and NiCoMnSn, respectively. Magnetization measurements show all the three compounds have a high Curie temperature (>583 K).

  8. Performance enhancement in uniaxially tensile stressed GeSn n-channel fin tunneling field-effect transistor: Impact of stress direction

    Science.gov (United States)

    Wang, Hongjuan; Han, Genquan; Jiang, Xiangwei; Liu, Yan; Zhang, Chunfu; Zhang, Jincheng; Hao, Yue

    2017-04-01

    In this work, the boosting effect on the performance of GeSn n-channel fin tunneling FET (nFinTFET) enabled by uniaxial tensile stress is investigated theoretically. As the fin rotates within the (001) plane, the uniaxial tensile stress is always along its direction. The electrical characteristics of tensile-stressed GeSn nFinTFETs with point and line tunneling modes are computed utilizing the technology computer aided design (TCAD) simulator in which the dynamic nonlocal band-to-band tunneling (BTBT) algorithm is employed. In comparison with the relaxed devices, tensile-stressed GeSn nFinTFETs achieve a substantial enhancement in band-to-band tunneling generation rate (G BTBT) and on-state current I ON owing to the reduced bandgap E G induced by the tensile stress. Performance improvement of GeSn nFinTFETs induced by tensile stress demonstrates a strong dependence on channel direction and tunneling modes. Under the same magnitude of stress, line-nFinTFETs obtain a more pronounced I ON enhancement over the transistors with point tunneling mode.

  9. Spin-orbit corrections to the indirect nuclear spin-spin coupling constants in XH4 (X=C, Si, Ge, and Sn)

    DEFF Research Database (Denmark)

    Kirpekar, Sheela; Jensen, Hans Jørgen Aagaard; Oddershede, Jens

    1997-01-01

    Using the quadratic response function at the ab initio SCF level of approximation we have calculated the relativistic corrections from the spin-orbit Hamiltonian, HSO, to the indirect nuclear spin-spin coupling constants of XH4 (X = C, Si, Ge, and Sn). We find that the spin-orbit contributions to...

  10. Characterization of optical constants and dispersion parameters of highly transparent Ge20Se76Sn4 amorphous thin film

    Science.gov (United States)

    Abd-Elrahman, M. I.; Hafiz, M. M.; Abdelraheem, A. M.; Abu-Sehly, A. A.

    2015-12-01

    Amorphous chalcogenide Ge20Se76Sn4 thin films of six different thicknesses (50-350 nm) are prepared by the thermal evaporation technique. Optical transmission and reflection spectra, in the wavelength range of the incident photons from 250 to 2500 nm, are used to study the effect of the film thickness on some optical properties. It is found that the effect of film thickness leads to increase in the absorption coefficient, refractive index, extinction coefficient and the width of the tails of localized states in the gap region. The decrease in optical band gap energy with increasing the film thickness is attributed to the formation of a band tail which narrows down the band gap. Dispersion analyses of refractive index reveal a decrease in the single-oscillator energy and an increase in the dispersion energy with increase in film thickness.

  11. Near-bandgap optical properties of pseudomorphic GeSn alloys grown by molecular beam epitaxy

    Science.gov (United States)

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

    2016-08-01

    We investigated the compositional dependence of the near-bandgap dielectric function and the E0 critical point in pseudomorphic Ge1-xSnx alloys grown on Ge (100) substrate by molecular beam epitaxy. The complex dielectric functions were obtained using spectroscopic ellipsometry from 0.5 to 4.5 eV at room temperature. Analogous to the E1 and E1+Δ1 transitions, a model consisting of the compositional dependence of relaxed alloys along with the strain contribution predicted by the deformation potential theory fully accounts for the observed compositional dependence in pseudomorphic alloys.

  12. Influence of growth and annealing temperature on the strain and surface morphology of Ge{sub 995}Sn{sub 0.005} epilayer

    Energy Technology Data Exchange (ETDEWEB)

    Su, Shaojian, E-mail: sushaojian@hqu.edu.cn [Fujian Provincial Key Laboratory of Light Propagation and Transformation, College of Information Science and Engineering, Huaqiao University, Xiamen City 361021, Fujian Province (China); Zhang, Dongliang; Xue, Chunlai [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Cheng, Buwen, E-mail: cbw@semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China)

    2015-06-15

    Highlights: • Ge{sub 0.995}Sn{sub 0.005} alloys were grown on Si (1 0 0) by MBE at 220–500 °C. • Surface roughening was enhanced with the increase of growth temperature. • Non-monotonic temperature dependence of the surface roughening was observed. • The incorporation of Sn into Ge helped release the residual heteroepitaxial strain. • The influence of annealing temperature on Ge{sub 0.995}Sn{sub 0.005} was also investigated. - Abstract: Ge{sub 1−x}Sn{sub x} alloys with low tin composition (0.5%) were grown directly on Si (1 0 0) substrates by molecular beam epitaxy at various temperatures ranging from 220 °C to 500 °C. In situ RHEED patterns, AFM images, and HR-XRD curves were measured to investigate the surface morphology and strain of the Ge{sub 0.995}Sn{sub 0.005} alloys. Surface roughening, which occurred during the deposition of the alloy, was found to be enhanced with the increase of the growth temperature T{sub G}. Compressive residual strain was introduced during low-temperature heteroepitaxial growth of the alloy. As T{sub G} was increased, it was gradually released, while the tensile thermal strain was increased. As a result, tensile in-plane strain was obtained provided T{sub G} was high enough (>420 °C). The influence of annealing temperature T{sub A} was investigated as well. It was shown that both surface morphology and stain of the alloy were only slightly changed with T{sub A} ≤ 600 °C. If T{sub A} was further increased, the surface roughness was significantly increased and the residual heteroepitaxial strain substantially released.

  13. First-principles study of new series of quaternary Heusler alloys CsSrCZ (Z=Si, Ge, Sn, P, As, and Sb)

    Energy Technology Data Exchange (ETDEWEB)

    Bouabça, A. [Condensed Matter and Sustainable Development Laboratory (LMCDD), University of Sidi Bel-Abbes, Sidi Bel-Abbes 22000 (Algeria); Rozale, H., E-mail: hrozale@yahoo.fr [Condensed Matter and Sustainable Development Laboratory (LMCDD), University of Sidi Bel-Abbes, Sidi Bel-Abbes 22000 (Algeria); Amar, A. [Condensed Matter and Sustainable Development Laboratory (LMCDD), University of Sidi Bel-Abbes, Sidi Bel-Abbes 22000 (Algeria); Wang, X.T. [School of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400044 (China); Sayade, A. [UCCS, CNRS-UMR 8181, Université d’Artois, Faculté des Sciences Jean Perrin, Rue Jean Souvraz, SP 18, 62307 Lens Cedex (France); Chahed, A. [Condensed Matter and Sustainable Development Laboratory (LMCDD), University of Sidi Bel-Abbes, Sidi Bel-Abbes 22000 (Algeria)

    2016-12-01

    The structural, electronic, magnetic, and thermal properties of new quaternary Heusler alloys CsSrCZ (Z=Si, Ge, Sn, P, As, and Sb) were investigated using the full-potential linearized augmented plane wave (FPLAPW) within the generalized gradient approximation (GGA) and GGA plus modified Becke and Johnson as the exchange correlation. The results showed that all Heusler compounds were stable in Type (I) structure. The CsSrCZ (Z=Si, Ge, Sn) compounds had a nearly HM characteristic, and CsSrCZ (Z=P, As, Sb) compounds were true half-metallic (HM) ferromagnets. The strong spin polarization of p orbital for C, Si, Ge, Sn, P, As, and Sb atoms is found to be the origin of ferromagnetic. The half-metallicity is preserved up to a lattice contraction of 3.45%, 1.69%, 1.69%, 7.16%, 7.16%, and 11.2% for all six quaternary Heusler compounds. We also investigated the thermal effects using the quasi-harmonic Debye model. - Highlights: • Electronic, magnetic, and thermodynamic properties of CsSrCZ (Z=Si, Ge, Sn, P, As, and Sb) are investigated. • Until now, there have been no reports theoretical and experimental studies on d{sup 0} half-metals with quaternary structures. • The strong spin polarization of p orbital for C, Si, Ge, Sn, P, As, and Sb atoms is found to be the origin of ferromagnetic. • The half-metallicity is preserved up to a lattice contraction.

  14. Energy dependence of particle ratio fluctuations in central Pb+Pb collisions from $\\sqrt{s_{_{NN}}} =$~6.3 to 17.3 GeV

    CERN Document Server

    Alt, C; Baatar, B; Barna, D; Bartke, J; Betev, L; Bialkowska, H; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Bunccic, P; Cerny, V; Christakoglou, P; Chvala, O; Cramer, J G; Csató, P; Dinkelaker, P; Eckardt, V; Flierl, D; Fodor, Z; Foka, P; Friese, V; Gál, J; Gazdzicki, M; Genchev, V; Georgopoulos, G; Gladysz, E; Grebieszkow, K; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kliemant, M; Kniege, S; Kolesnikov, V I; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Kresan, D; Van Leeuwen, M; Lévai, P; Litov, L; Lungwitz, B; Makariev, M; Malakhov, A I; Mateev, M; Melkumov, G L; Mischke, A; Mitrovski, M; Molnár, J; Mrówczynski, St; Nicolic, V; Pálla, G; Panagiotou, A D; Panayotov, D; Petridis, A; Pikna, M; Prindle, D; Pühlhofer, F; Renfordt, R; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Schuster, T; Seyboth, P; Siklér, F; Sitár, B; Skrzypczak, E; Stefanek, G; Stock, R; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Szymanski, P; Trubnikov, V; Varga, D; Vassiliou, M; Veres, G I; Vesztergombi, G; Vranic, D; Wetzler, A; Wlodarczyk, Z; Yoo, I K

    2009-01-01

    We present recent measurements of the energy dependence of event-by-event fluctuations in the K/pi and (p + \\bar{p})/pi multiplicity ratios in heavy ion collisions at the CERN SPS. The particle ratio fluctuations were obtained for central Pb+Pb collisions at five collision energies, \\sqrt{s_{_{NN}}}, between 6.3 and 17.3 GeV. After accounting for the effects of finite-number statistics and detector resolution, we extract the strength of non-statistical fluctuations at each energy. For the K/pi ratio, larger fluctuations than expected for independent particle production are found at all collision energies. The fluctuations in the (p + \\bar{p})/pi ratio are smaller than expectations from independent particle production, indicating correlated pion and proton production from resonance decays. For both ratios, the deviation from purely statistical fluctuations shows an increase towards lower collision energies. The results are compared to transport model calculations, which fail to describe the energy dependence o...

  15. Si(001)衬底上分子束外延生长Ge0.975Sn0.025合金薄膜%Epitaxial growth of Ge0.975Sn0.025 alloy films on Si(001) substrates by molecular beam epitaxy

    Institute of Scientific and Technical Information of China (English)

    苏少坚; 汪巍; 张广泽; 胡炜玄; 白安琪; 薛春来; 左玉华; 成步文; 王启明

    2011-01-01

    使用低、高温两步法生长的高质量Ge薄膜作为缓冲层,在Si(001)衬底上采用分子束外延法生长出Ge0.975Sn0.025合金薄膜.X射线双晶衍射和卢瑟福背散射谱等测试结果表明,Ge0.975Sn0.025合金薄膜具有很好的晶体质量,并且没有发生Sn表面分疑.另外,Ge0.975Sn0.025合金薄膜在500 ℃下具有很好的热稳定性,有望在Si基光电器件中得到应用.

  16. Design of Three-shell Icosahedral Matryoshka Clusters A@B12@A20 (A = Sn, Pb; B = Mg, Zn, Cd, Mn)

    Science.gov (United States)

    Huang, Xiaoming; Zhao, Jijun; Su, Yan; Chen, Zhongfang; King, R. Bruce

    2014-11-01

    We propose a series of icosahedral matryoshka clusters of A@B12@A20 (A = Sn, Pb; B = Mg, Zn, Cd), which possess large HOMO-LUMO gaps (1.29 to 1.54 eV) and low formation energies (0.06 to 0.21 eV/atom). A global minimum search using a genetic algorithm and density functional theory calculations confirms that such onion-like three-shell structures are the ground states for these A21B12 binary clusters. All of these icosahedral matryoshka clusters, including two previously found ones, i.e., [As@Ni12@As20]3- and [Sn@Cu12@Sn20]12-, follow the 108-electron rule, which originates from the high Ih symmetry and consequently the splitting of superatom orbitals of high angular momentum. More interestingly, two magnetic matryoshka clusters, i.e., Sn@Mn12@Sn20 and Pb@Mn12@Pb20, are designed, which combine a large magnetic moment of 28 µB, a moderate HOMO-LUMO gap, and weak inter-cluster interaction energy, making them ideal building blocks in novel magnetic materials and devices.

  17. EXCITATION OF GIANT-RESONANCES IN PB-208, SN-120, ZR-90 AND NI-60 BY 84 MEV/NUCLEON O-17 IONS

    NARCIS (Netherlands)

    NETO, RL; ROUSSELCHOMAZ, P; ROCHAIS, L; ALAMANOS, N; AUGER, F; GASTEBOIS, J; GILLIBERT, A; LACEY, R; MICZAIKA, A; PIERROUTSAKOU, D; BARRETTE, J; MARK, SK; TURCOTTE, R; BLUMENFELD, Y; FRASCARIA, N; GARRON, JP; ROYNETTE, JC; SCARPACI, JA; SUOMIJARVI, T; VANDERWOUDE, A; VANDENBERG, AM

    1993-01-01

    Elastic and inelastic scattering of 1435 MeV 170 ions on Pb-208, Sn-120, Zr-90 and Ni-60 have been measured. Hindrance in the excitation of the first 3- states is observed. Parameters of the isoscalar giant monopole and quadrupole resonances are obtained. The quadrupole resonance exhausts approximat

  18. Cross sections of production of J / {psi}, {psi}` resonances and of the Drell-Yan process in the Pb-Pb interactions with 158 GeV / c per nucleon; Section efficaces de production des resonances J / {psi}, {psi}` et du processus Drell-Yan dans les interactions Pb-Pb a 158 GeV / c par nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Bellaiche, F

    1997-04-24

    In the framework of the experimental research for the quark and gluons plasma formation in ultrarelativistic heavy ion collisions, data obtained by the NA50 collaboration at SPS-CERN are analysed. The segmented target used by NA50 experiment is described and analysed in terms of vertex identification efficiency and re-interactions recognition. The absolute J/{psi}, {psi}`and Drell-Yan process cross-sections in 158 GeV/c per nucleon Pb-Pb interactions are extracted. The transverse energy dependence of the production yield of J/{psi} and Drell-Yan process is established. The comparison of these cross-sections with the ones measured in lighter systems and the comparison of the E dependence of J/{psi} production with the Glauber model prediction show an anomalous J/{psi} suppression observed in Pb-Pb interactions is confronted to theoretical models proposed by several authors, describing charmonium bound states formation and interactions is confronted to theoretical models proposed by several authors, describing charmonium bound states formation and interactions in confined or deconfined media. (author) 122 refs.

  19. Self-annealing in a two-phase Pb-Sn alloy after processing by high-pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Nian Xian [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Chinh, Nguyen Q. [Department of Materials Physics, Eötvös Loránd University, 1117 Budapest, Pázmány Péter s. 1/A. (Hungary); Kawasaki, Megumi [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Departments of Aerospace & Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453 (United States); Huang, Yi, E-mail: Y.Huang@soton.ac.uk [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Langdon, Terence G. [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Departments of Aerospace & Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453 (United States)

    2016-06-01

    A Pb-62% Sn two-phase eutectic alloy was processed by high-pressure torsion (HPT) and stored at room temperature (RT) to investigate the occurrence of self-annealing. The microstructural characteristics and mechanical properties were recorded during self-annealing using scanning electron microscopy, tensile testing and nanoindentation. Processing by HPT produces a weakening effect but storage at RT leads to a gradual increase in the hardness together with significant grain growth. Nanoindentation tests were performed by applying both the indentation depth-time (h-t) relationship at the holding stage and the hardness, H, at various loading rates in order to explore the evolution of the strain rate sensitivity (SRS), m. The results obtained by tensile testing and nanoindentation are consistent despite the large difference in the volumes of the examined regions, thereby confirming the validity of using nanoindentation to measure the strain rate sensitivity.

  20. Simulation of thermos-solutal convection induced macrosegregation in a Sn-10%Pb alloy benchmark during columnar solidification

    Science.gov (United States)

    Zheng, Y.; Wu, M.; Kharicha, A.; Ludwig, A.

    2016-03-01

    In order to investigate the effect of thermo-solutal convection on the formation of macrosegregation during columnar solidification, simulations with a liquid-columnar two phase model were carried out on a 2D rectangular benchmark of Sn-10%Pb alloy. The solidification direction in the benchmark is unidirectional: (') downwards from top to bottom or (2) upwards from bottom to top. Thermal expansion coefficient, solutal expansion coefficient and liquid diffusion coefficient of the melt are found to be key factors influencing the final macrosegregation. The segregation range and distribution are also strongly influenced by the benchmark configurations, e.g. the solidifying direction (upwards or downwards) and boundary conditions, et al. The global macrosegregation range increases with the velocity magnitude of the melt during the process of solidification.

  1. Characterization of Ni/SnPb-TiW/Pt Flip Chip Interconnections in Silicon Pixel Detector Modules

    CERN Document Server

    Karadzhinova, Aneliya; Härkönen, Jaakko; Luukka, Panja-riina; Mäenpää, Teppo; Tuominen, Eija; Haeggstrom, Edward; Kalliopuska, Juha; Vahanen, Sami; Kassamakov, Ivan

    2014-01-01

    In contemporary high energy physics experiments, silicon detectors are essential for recording the trajectory of new particles generated by multiple simultaneous collisions. Modern particle tracking systems may feature 100 million channels, or pixels, which need to be individually connected to read-out chains. Silicon pixel detectors are typically connected to readout chips by flip-chip bonding using solder bumps. High-quality electro-mechanical flip-chip interconnects minimizes the number of dead read-out channels in the particle tracking system. Furthermore, the detector modules must endure handling during installation and withstand heat generation and cooling during operation. Silicon pixel detector modules were constructed by flip-chip bonding 16 readout chips to a single sensor. Eutectic SnPb solder bumps were deposited on the readout chips and the sensor chips were coated with TiW/Pt thin film UBM (under bump metallization). The modules were assembled at Advacam Ltd, Finland. We studied the uniformity o...

  2. Study of low-defect and strain-relaxed GeSn growth via reduced pressure CVD in H2 and N2 carrier gas

    Science.gov (United States)

    Margetis, J.; Mosleh, A.; Al-Kabi, S.; Ghetmiri, S. A.; Du, W.; Dou, W.; Benamara, M.; Li, B.; Mortazavi, M.; Naseem, H. A.; Yu, S.-Q.; Tolle, J.

    2017-04-01

    High quality, thick (up to 1.1 μm), strain relaxed GeSn alloys were grown on Ge-buffered Si (1 0 0) in an ASM Epsilon® chemical vapor deposition system using SnCl4 and low-cost commercial GeH4 precursors. The significance of surface chemistry in regards to growth rate and Sn-incorporation is discussed by comparing growth kinetics data in H2 and N2 carrier gas. The role of carrier gas is also explored in the suppression of Sn surface segregation and evolution of layer composition and strain profiles via secondary ion mass spectrometry and X-ray diffraction. Transmission electron microscopy revealed the spontaneous compositional splitting and formation of a thin intermediate layer in which dislocations are pinned. This intermediate layer enables the growth of a thick, strain relaxed, and defect-free epitaxial layer on its top. Last, we present photoluminescence results which indicate that both N2 and H2 growth methods produce optoelectronic device quality material.

  3. Thermal stability and relaxation mechanisms in compressively strained Ge{sub 0.94}Sn{sub 0.06} thin films grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Fleischmann, C.; Lieten, R. R.; Shimura, Y.; Vandervorst, W. [Instituut voor Kern-en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium); imec, Kapeldreef 75, 3001 Leuven (Belgium); Hermann, P.; Hönicke, P.; Beckhoff, B. [Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, 10587 Berlin (Germany); Seidel, F. [Instituut voor Kern-en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium); imec, Kapeldreef 75, 3001 Leuven (Belgium); Institut für Elektronik-und Sensormaterialien, TU Bergakademie Freiberg, Gustav-Zeuner-Str. 3, 09599 Freiberg (Germany); Richard, O.; Bender, H. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Zaima, S. [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Uchida, N. [Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba West SCR, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Temst, K.; Vantomme, A. [Instituut voor Kern-en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium)

    2016-08-28

    Strained Ge{sub 1-x}Sn{sub x} thin films have recently attracted a lot of attention as promising high mobility or light emitting materials for future micro- and optoelectronic devices. While they can be grown nowadays with high crystal quality, the mechanism by which strain energy is relieved upon thermal treatments remains speculative. To this end, we investigated the evolution (and the interplay) of composition, strain, and morphology of strained Ge{sub 0.94}Sn{sub 0.06} films with temperature. We observed a diffusion-driven formation of Sn-enriched islands (and their self-organization) as well as surface depressions (pits), resulting in phase separation and (local) reduction in strain energy, respectively. Remarkably, these compositional and morphological instabilities were found to be the dominating mechanisms to relieve energy, implying that the relaxation via misfit generation and propagation is not intrinsic to compressively strained Ge{sub 0.94}Sn{sub 0.06} films grown by molecular beam epitaxy.

  4. The contents of heavy metals (cd, cr, as, pb, ni, and sn) in the selected commercial yam powder products in South Korea.

    Science.gov (United States)

    Shin, Mee-Young; Cho, Young-Eun; Park, Chana; Sohn, Ho-Yong; Lim, Jae-Hwan; Kwun, In-Sook

    2013-12-01

    Yam (Dioscorea) has long been used as foods and folk medicine with the approved positive effects for health promotion. Although consumption of yam products is increasing for health promotion, reports for the metal contamination in commercial yam powder products to protect the consumers are lacking. In this study, we aimed to assess whether the commercial yam powder products were heavy metal contaminated or not using the yam products from six commercial products from various places in South Korea. The contents of heavy metals (Cd, Cr, As, Pb, Ni, and Sn) in yam powder products were measured and compared to national and international food standard levels. Also, the metal contamination was monitored during the food manufacturing steps. The study results showed that the contents of heavy metals (Cd, Cr, As, and Pb) in yam powder products are similar to those in national 'roots and tubers' as well as in various crops. In comparison to three international standard levels (EU, Codex and Korea), Cd content in yam powder products was lower but Pb content was 5 times higher. Also, Pb, Ni, and Sn may have the potential to be contaminated during food manufacturing steps. In conclusion, the level of heavy metals (Cd, Cr, As, Ni, and Sn) except Pb is considered relatively safe on comparison to national and international food standard levels.

  5. Effects of bismuth on growth of intermetallic compounds in Sn-Ag-Cu Pb-free solder joints

    Institute of Scientific and Technical Information of China (English)

    LI Guo-yuan; SHI Xun-qing

    2006-01-01

    The effects of Bi addition on the growth of intermetallic compound (IMC) formation in Sn-3.8Ag-0.7Cu solder joints were investigated. The test samples were prepared by conventional surface mounting technology. To investigate the element diffusion and the growth kinetics of intermetallics formation in solder joint,isothermal aging test was performed at temperatures of 100,150,and 190 ℃,respectively. The optical microscope (OM) and scanning electron microscope (SEM) were used to observe microstructure evolution of solder joint and to estimate the thickness and the grain size of the intermetallic layers. The IMC phases were identified by energy dispersive X-ray (EDX) and X-ray diffractometer (XRD). The results clearly show that adding about 1.0% Bi in Sn-Ag-Cu solder alloy system can refine the grain size of the IMC and inhibit the excessive IMC growth in solder joints,and therefore improve the reliability of the Pb-free solder joints. Through observation of the microstructural evolution of the solder joints,the mechanism of inhibition of IMC growth due to Bi addition was proposed.

  6. Structural, elastic, electronic, bonding, and optical properties of BeAZ{sub 2} (A = Si, Ge, Sn; Z = P, As) chalcopyrites

    Energy Technology Data Exchange (ETDEWEB)

    Fahad, Shah [Department of Physics, Hazara University Mansehra, KPK, Mansehra (Pakistan); Murtaza, G., E-mail: murtaza@icp.edu.pk [Materials Modeling Laboratory, Department of Physics, Islamia College University, Peshawar (Pakistan); Ouahrani, T. [Laboratoire de Physique Théorique, B.P. 230, Université de Tlemcen, Tlemcen 13000 (Algeria); Ecole Préparatoire en Sciences et Techniques, BP 165 R.P., 13000 Tlemcen (Algeria); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 (Algeria); Yousaf, Masood [Center for Multidimensional Carbon Materials, Institute for Basic Science, Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of); Omran, S.Bin [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Mohammad, Saleh [Department of Physics, Hazara University Mansehra, KPK, Mansehra (Pakistan)

    2015-10-15

    A first principles density functional theory (DFT) technique is used to study the structural, chemical bonding, electronic and optical properties of BeAZ{sub 2} (A = Si, Ge, Sn; Z = P, As) chalcopyrite materials. The calculated parameters are in good agreement with the available experimental results. The lattice constants and the equilibrium volume increased as we moved from Si to Ge to Sn, whereas the c/a and internal parameters u decreased by shifting the cation from P to As. These compounds are elastically stable. An investigation of the band gap using the WC-GGA, EV-GGA, PBE-GGA and mBJ-metaGGA potentials suggested that BeSiP{sub 2} and BeSiAs{sub 2} are direct band gap compounds, whereas BeGeP{sub 2,} BeGeAs{sub 2,} BeSnP{sub 2,} BeSnAs{sub 2} are indirect band gap compounds. The energy band gaps decreased by changing B from Si to Sn and increased by changing the anion C from P to As. The bonding among the cations and anions is primarily ionic. In the optical properties, the real and imaginary parts of the dielectric functions, reflectivity and optical conductivity have been studied over a wide energy range. - Highlights: • The compounds are studied by FP-LAPW method within mBJ approximation. • All of the studied materials show isotropic behaviour. • All the compounds show direct band gap nature. • Bonding nature is mostly covalent among the studied compounds. • High absorption peaks and reflectivity ensures there utility in optoelectronic devices.

  7. Transport properties of Heusler compounds Ru{sub 2}CrGe and Ru{sub 2}CrSn under high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Okada, H; Koyama, K; Watanabe, K [High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku University, Sendai (Japan); Kusakari, Y; Kanomata, T [Faculty of Engineering, Tohoku Gakuin University, Tagajo (Japan); Matsuoka, E; Onodera, H, E-mail: hironari@imr.tohoku.ac.j [Department of Physics, Graduate School of Science, Sendai (Japan)

    2009-03-01

    We have performed the specific heat and the electrical resistivity measurements under high magnetic fields for Heusler compounds Ru{sub 2}CrGe and Ru{sub 2}CrSn. We found that the electrical resistivity for Ru{sub 2}CrGe shows an upturn in the vicinity of 130 K and changes a metallic to a semiconducting-like behavior with decreasing temperature. By applying magnetic field, a negative magnetoresistance was observed below 200 K. On the other hand, the electrical resistivity for Ru{sub 2}CrSn shows a semimetallic-like behavior. The results of the electrical resistivity in Ru{sub 2}CrGe suggest that the compound has a gap-like structure in the electronic structure at the Fermi level. Moreover, it was found that another phase transition occurs in Ru{sub 2}CrGe and Ru{sub 2}CrSn, in addition to the magnetic transition.

  8. Structure and defect processes in Si{sub 1-x-y}Ge{sub x}Sn{sub y} random alloys

    Energy Technology Data Exchange (ETDEWEB)

    Schwingenschloegl, U. [PSE Division, KAUST, Thuwal (Saudi Arabia); Chroneos, A.; Grimes, R.W. [Department of Materials, Imperial College London (United Kingdom); Jiang, C. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM (United States); Bracht, H. [Institute of Material Physics, University of Muenster (Germany)

    2010-07-01

    Binary and ternary Si{sub 1-x-y}Ge{sub x}Sn{sub y} random alloys are being considered as candidate materials to lattice match III-V or II-VI compounds with Si or Ge in optoelectronic or microelectronic devices. The simulation of the defect interactions of these alloys is hindered by their random nature. Here we use the special quasirandom approach (SQS) in conjunction with density functional theory calculations to study the structure and the defect processes. For the binary alloy Ge{sub x}Sn{sub 1-x} the SQS method correctly describes the deviation of the lattice parameters from Vegard's Law. For the ternary alloy Si{sub 0.375}Ge{sub 0.5}Sn{sub 0.125} we find an association of As atoms to lattice vacancies and the formation of As-vacancy pairs. It is predicted that the nearest-neighbour environment exerts a strong influence on the stability of these pairs.

  9. Lattice parameter values and magnetic properties for the Mn{sub 2}GeTe{sub 4}, Fe{sub 2}GeTe{sub 4} and Fe{sub 2}SnSe{sub 4} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Quintero, M. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de los Andes, Merida 5101 (Venezuela, Bolivarian Republic of)], E-mail: mquinter@ula.ve; Ferrer, D.; Caldera, D.; Moreno, E.; Quintero, E.; Morocoima, M.; Grima, P.; Bocaranda, P. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Delgado, G.E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Henao, J.A. [Grupo de Investigacion en Quimica Estructural (GIQUE), Facultad de Ciencias, Escuela de Quimica, Universidad Industrial de Santander, Apartado aereo 678, Bucaramanga (Colombia)

    2009-02-05

    X-ray powder diffraction measurements, at room temperature, and magnetic susceptibility {chi} measurements, in the temperature range from 2 to 300 K, were made on polycrystalline samples of Mn{sub 2}GeTe{sub 4}, Fe{sub 2}GeTe{sub 4} and Fe{sub 2}SnSe{sub 4} compounds, which would be useful for spintronic device production. Magnetization M measurements at various temperatures were carried out on the Fe-compounds. From the analysis of the X-ray diffraction patterns, it was found that the Mn{sub 2}GeTe{sub 4}, Fe{sub 2}GeTe{sub 4} and Fe{sub 2}SnSe{sub 4} have orthorhombic structure, possibly an olivine structure-type (SG: Pnma No. 62, z = 4). It was found that Mn{sub 2}GeTe{sub 4} has a Neel temperature of 30 K, shows mainly antiferromagnetic behavior with a weak superimposed ferromagnetic component which is attributed to spin canting. The resulting susceptibility {chi} versus T curves for Fe{sub 2}GeTe{sub 4} and Fe{sub 2}SnSe{sub 4} were found to have, in each case, a form which is typical of a ferromagnetic material with Curie temperatures T{sub C} of 149.9 and 301 K, respectively. The critical exponent {beta} for the Fe-compounds were found to be very similar and close to the expected value for a ferromagnetic material, in the range 0.33-0.39. The values of the coercive field B{sub C} and the remanent magnetization M{sub r} were found to vary nonlinearly with the temperature T.

  10. In situ measurement of electromigration-induced transient stress in Pb-free Sn-Cu solder joints by synchrotron radiation based X-ray polychromatic microdiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Kai; Tamura, Nobumichi; Kunz, Martin; Tu, King-Ning; Lai, Yi-Shao

    2009-12-01

    Electromigration-induced hydrostatic elastic stress in Pb-free SnCu solder joints was studied by in situ synchrotron X-ray white beam microdiffraction. The elastic stresses in two different grains with similar crystallographic orientation, one located at the anode end and the other at the cathode end, were analyzed based on the elastic anisotropy of the Beta-Sn crystal structure. The stress in the grain at the cathode end remained constant except for temperature fluctuations, while the compressive stress in the grain at the anode end was built-up as a function of time during electromigration until a steady state was reached. The measured compressive stress gradient between the cathode and the anode is much larger than what is needed to initiate Sn whisker growth. The effective charge number of Beta-Sn derived from the electromigration data is in good agreement with the calculated value.

  11. In situ measurement of electromigration-induced transient stress in Pb-free Sn-Cu solder joints by synchrotron radiation based X-ray polychromatic microdiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Kai; Tamura, Nobumichi; Kunz, Martin; Tu, King-Ning; Lai, Yi-Shao

    2009-05-15

    Electromigration-induced hydrostatic elastic stress in Pb-free SnCu solder joints was studied by in situ synchrotron X-ray white beam microdiffraction. The elastic stresses in two different grains with similar crystallographic orientation, one located at the anode end and the other at the cathode end, were analyzed based on the elastic anisotropy of the {beta}-Sn crystal structure. The stress in the grain at the cathode end remained constant except for temperature fluctuations, while the compressive stress in the grain at the anode end was built-up as a function of time during electromigration until a steady state was reached. The measured compressive stress gradient between the cathode and the anode is much larger than what is needed to initiate Sn whisker growth. The effective charge number of {beta}-Sn derived from the electromigration data is in good agreement with the calculated value.

  12. Scale-dependence of transverse momentum correlations in Pb-Au collisions at 158A GeV/c

    CERN Document Server

    Adamová, D; Antonczyk, D; Appelshäuser, H; Belaga, V; Bielcikova, S; Braun-Munzinger, P; Busch, O; Cherlin, A; Damjanovic, S; Dietel, T; Dietrich, L; Drees, A; Dubitzky, W; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Zeev; Garabatos, C; Glässel, P; Holeczek, J; Kushpil, V; Maas, A; Marín, A; Milosevic, J; Milov, A; Miskowiec, D; Panebratsev, Yu A; Petchenova, O; Petracek, V; Pfeiffer, A; Ploskon, M; Radomski, S; Rak, acn J; Ravinovich, I; Rehak, P; Sako, H; Schmitz, W; Sedykh, S; Shimansky, S; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, Itzhak; Tsiledakis, G; Wessels, J P; Wienold, T; Wurm, J P; Xie, W; Yurevich, S; Yurevich, V

    2008-01-01

    We present results on transverse momentum correlations of charged particle pairs produced in Pb-Au collisions at 158$A$ GeV/$c$ at the Super Proton Synchrotron. The transverse momentum correlations have been studied as a function of collision centrality, angular separation of the particle pairs, transverse momentum and charge sign. We demonstrate that the results are in agreement with previous findings in scale-independent analyses at the same beam energy. Employing the two-particle momentum correlator $$ and the cumulative $p_t$ variable $x(p_t)$, we identify, using the scale-dependent approach presented in this paper, different sources contributing to the measured correlations, such as quantum and Coulomb correlations, elliptic flow and mini-jet fragmentation.

  13. Antiproton Production in 11.5A GeV/c Au+Pb Nucleus-Nucleus Collisions

    Energy Technology Data Exchange (ETDEWEB)

    De Cataldo, G.; Giglietto, N.; Raino, A.; Spinelli, P. [University of Bari/INFN, Bari (Italy); Dover, C.B. [Brookhaven National Laboratory, Upton, New York 11973 (United States); Huang, H.Z. [University of California at Los Angeles, Los Angeles, California 90024 (United States); Hill, J.C.; Libby, B.; Wohn, F.K. [Iowa State University, Ames, Iowa 50011 (United States); Rabin, M.S. [University of Massachusetts, Amherst, Massachusetts 01003 (United States); Haridas, P.; Pless, I.A.; Van Buren, G. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Armstrong, T.A.; Lewis, R.A.; Reid, J.D.; Smith, G.A.; Toothacker, W.S. [Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Davies, R.; Hirsch, A.S.; Porile, N.T.; Rimai, A.; Scharenberg, R.P.; Srivastava, B.K.; Tincknell, M.L. [Purdue University, West Lafayette, Indiana 47907 (United States); Greene, S.V. [Vanderbilt University, Nashville, Tennessee 37235 (United States); Bennett, S.J.; Cormier, T.M.; Dee, P.; Fachini, P.; Kim, B.; Li, Q.; Li, Y.; Munhoz, M.G.; Pruneau, C.A.; Wilson, W.K.; Zhao, K. [Wayne State University, Detroit, Michigan 48201 (United States); Barish, K.N.; Bennett, M.J.; Chikanian, A.; Coe, S.D.; Diebold, G.E.; Finch, L.E.; George, N.K.; Kumar, B.S.; Lajoie, J.G.; Majka, R.D.; Nagle, J.L.; Pope, J.K.; Rotondo, F.S.; Sandweiss, J.; Slaughter, A.J.; Wolin, E.J. [Yale University, New Haven, Connecticut 06520 (United States)

    1997-11-01

    We present the first results from the E864 Collaboration on the production of antiprotons in 10{percent} central 11.5A GeV /c Au+Pb nucleus collisions at the Brookhaven Alternating Gradient Synchrotron. We report invariant multiplicities for antiproton production in the kinematic region 1.4{lt}y{lt}2.2 and 50{lt} p{sub T}{lt} 300 MeV/c , and compare our data with a first collision scaling model and previously published results from the E878 Collaboration. The differences between the E864 and E878 antiproton measurements and the implications for antihyperon production are discussed. {copyright} {ital 1997} {ital The American Physical Society}

  14. Azimuthal anisotropy of charged particles with transverse momentum up to 100 GeV in PbPb collisions at $\\sqrt{s_{NN}}$ = 5.02 TeV

    Energy Technology Data Exchange (ETDEWEB)

    Sirunyan, Albert M; et al.

    2017-02-02

    The Fourier coefficients v[2] and v[3] characterizing the anisotropy of the azimuthal distribution of charged particles produced in PbPb collisions at $\\sqrt{s_{NN}}$ = 5.02 TeV are measured with data collected by the CMS experiment. The measurements cover a broad transverse momentum range, pt= 1-100 GeV. The analysis focuses on pt > 10 GeV range, where anisotropic azimuthal distributions should reflect the path-length dependence of parton energy loss in the created medium. Results are presented in several bins of PbPb collision centrality, spanning the 60x% most central events. The v[2] coefficient is measured with the scalar product and the multiparticle cumulant methods, which have different sensitivities to the initial-state fluctuations. The values of both methods remain positive up to pt ~ 70 GeV, in all examined centrality classes. The v[3] coefficient, only measured with the scalar product method, tends to zero for pt >~ 20 GeV. Comparisons between theoretical calculations and data provide new constraints on the path-length dependence of parton energy loss in heavy ion collisions and highlight the importance of the initial-state fluctuations.

  15. Kaon and pion production in centrality selected minimum bias Pb+Pb collisions at 40 and 158 A.GeV

    Energy Technology Data Exchange (ETDEWEB)

    Dinkelaker, Peter

    2009-07-01

    Results on charged kaon and negatively charged pion production and spectra for centrality selected Pb+Pb minimum bias events at 40 and 158A GeV have been presented in this thesis. All analysis are based on data taken by the NA49 experiment at the accelerator Super Proton Synchrotron (SPS) at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland. The kaon results are based on an analysis of the mean energy loss of the charged particles traversing the detector gas of the time projection chambers (TPCs). The pion results are from an analysis of all negatively charged particles h{sup -} corrected for contributions from particle decays and secondary interactions. For the dE/dx analysis of charged kaons, main TPC tracks with a total momentum between 4 and 50 GeV have been analyzed in logarithmic momentum log(p) and transverse momentum p{sub t} bins. The resulting dE/dx spectra have been fitted by the sum of 5 Gaussians, one for each main particle type (electrons, pions, kaons, protons, deuterons). The amplitude of the Gaussian used for the kaon part of the spectra has been corrected for efficiency and acceptance and the binning has been transformed to rapidity y and transverse momentum pt bins. The multiplicity dN/dy of the single rapidity bins has been derived by summing the measured range of the transverse momentum spectra and an extrapolation to full coverage with a single exponential function fitted to the measured range. The results have been combined with the mid-rapidity measurements from the time-of-flight detectors and a double Gaussian fit to the dN/dy spectra has been used for extrapolation to rapidity outside of the acceptance of the dE/dx analysis. For the h{sup -} analysis of negatively charged pions, all negatively charged tracks have been analyzed. The background from secondary reactions, particle decays, and gamma-conversions has been corrected with the VENUS event generator. The results were also corrected for efficiency

  16. Measurement of negative particle multiplicity in S-Pb collisions at 200 GeV/c per nucleon with the NA36 TPC

    CERN Document Server

    Andersen, E; Brom, J M; Cherney, M; de la Cruz, B; Fernández, C; Garabatos, C; Garzón, J A; Geist, Walter M; Greiner, D E; Gruhn, Charles R; Hafidouni, M; Hrubec, Josef; Jones, P G; Judd, E G; Kuipers, J P M; Ladrem, M; Ladrón de Guevara, P; Løvhøiden, G; MacNaughton, J N; Mosquera, J; Natkaniec, Z; Nelson, J M; Neuhofer, Günther; Pérez de los Heros, C; Pló, M; Porth, Paul; Powell, B; Ramil, A; Rohringer, Herbert; Sakrejda, I; Thorsteinsen, T F; Traxler, J; Voltolini, C; Wozniak, K; Yañez, A; Zybert, R

    2001-01-01

    A high statistics study of the negative multiplicity distribution from S-Pb collisions at 200 GeV/c per nucleon is presented. The NA36 TPC was used to detect charged particles; corrections are based upon the maximum entropy method.

  17. Morphology and Hardness Improvement of Lead Bearing Alloy through Composite Production: 75Pb-15Sb-10Sn/ 15% V/V SiO2 Particulate Composite

    Directory of Open Access Journals (Sweden)

    Linus Okon ASUQUO

    2013-06-01

    Full Text Available The morphology and hardness improvement of lead bearing alloy through composite production: 75Pb-15Sb-10Sn/ 15%v/v SiO2 particulate composite, was studied. 75Pb-15Sb-10Sn white bearing alloy produced at the foundry shop of National Metallurgical Development Centre Jos was used for the production of the composite using stir-cast method. The reinforcing agent was 63 microns passing particles of silica. This was produced from pulverizing quartz using laboratory ball mill. The specimens of the composite produced were then subjected to metallographic to study the morphology of the structures produced both in the as cast and aged conditions of the composite. The samples were also tested for hardness and the result showed that the as cast composite had a hardness value of 33 HRB which is an improvement over the hardness value of 27.7 HRB for the 75Pb-15Sb-10Sn alloy which was used for the production of the composite. The effect of age hardening on the produced composite was also investigated; the result showed that the maximum hardness of 34 HRB was obtained after ageing for 3 hours. The micrographs revealed inter-metallic compound SbSn, eutectic of two solid solutions-one tin-rich and the other lead-rich, reinforcing particles, and solid solution of β. The results revealed that particle hardening can be used to improve the hardness of 75Pb-15Sb-10Sn white bearing alloy for use as heavy duty bearing material.

  18. Towards from indirect to direct band gap and optical properties of XYP{sub 2} (X=Zn, Cd; Y=Si, Ge, Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Ullah, Sibghat [Department of Physics, Hazara University Mansehra, KPK (Pakistan); Murtaza, G., E-mail: murtaza@icp.edu.pk [Materials Modeling Lab, Department of Physics, Islamia College, Peshawar (Pakistan); Khenata, R. [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 Mascara (Algeria); Reshak, A.H. [New Technologies—Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Hayat, S.S. [Department of Physics, Hazara University Mansehra, KPK (Pakistan); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)

    2014-05-15

    First principle calculations are performed to predict the electronic and optical properties of XYP{sub 2} (X=Zn, Cd; Y=Si, Ge, Sn) compounds. The calculations show an excellent agreement with the available experimental results as compared to previous calculations. The band gap value decreases by changing the cations X from Zn to Cd as well as Y from Si to Ge to Sn in XYP{sub 2}. The d-states of the Zn and Cd contribute majorly in the density of states. Bonding nature in these compounds is analyzed from the electron density plots. Optical response of these compounds is noted from the complex refractive index and reflectivity spectra. The wide direct band gap and the high reflectivity in the visible and ultraviolet regions for these compounds make them potential candidates for optoelectronic and photonic applications.

  19. First-principles study of the structural stability of cubic, tetragonal and hexagonal phases in Mn₃Z (Z=Ga, Sn and Ge) Heusler compounds.

    Science.gov (United States)

    Zhang, Delin; Yan, Binghai; Wu, Shu-Chun; Kübler, Jürgen; Kreiner, Guido; Parkin, Stuart S P; Felser, Claudia

    2013-05-22

    We investigate the structural stability and magnetic properties of the cubic, tetragonal and hexagonal phases of Mn3Z (Z=Ga, Sn and Ge) Heusler compounds using first-principles density-functional theory. We propose that the cubic phase plays an important role as an intermediate state in the phase transition from the hexagonal to the tetragonal phases. Consequently, Mn3Ga and Mn3Ge behave differently from Mn3Sn, because the relative energies of the cubic and hexagonal phases are different. This result agrees with experimental observations for these three compounds. The weak ferromagnetism of the hexagonal phase and the perpendicular magnetocrystalline anisotropy of the tetragonal phase obtained in our calculations are also consistent with experiment.

  20. First-principles study of the structural stability of cubic, tetragonal and hexagonal phases in Mn3Z (Z=Ga, Sn and Ge) Heusler compounds

    Science.gov (United States)

    Zhang, Delin; Yan, Binghai; Wu, Shu-Chun; Kübler, Jürgen; Kreiner, Guido; Parkin, Stuart S. P.; Felser, Claudia

    2013-05-01

    We investigate the structural stability and magnetic properties of the cubic, tetragonal and hexagonal phases of Mn3Z (Z=Ga, Sn and Ge) Heusler compounds using first-principles density-functional theory. We propose that the cubic phase plays an important role as an intermediate state in the phase transition from the hexagonal to the tetragonal phases. Consequently, Mn3Ga and Mn3Ge behave differently from Mn3Sn, because the relative energies of the cubic and hexagonal phases are different. This result agrees with experimental observations for these three compounds. The weak ferromagnetism of the hexagonal phase and the perpendicular magnetocrystalline anisotropy of the tetragonal phase obtained in our calculations are also consistent with experiment.

  1. Reflection high energy electron diffraction studies on Si{sub x}Sn{sub y}Ge{sub 1−x−y} on Si(100) molecular beam epitaxial growth

    Energy Technology Data Exchange (ETDEWEB)

    Nikiforov, A.I., E-mail: nikif@isp.nsc.ru [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Lavrentjeva 13, 630090 Novosibirsk (Russian Federation); Mashanov, V.I.; Timofeev, V.A.; Pchelyakov, O.P. [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Lavrentjeva 13, 630090 Novosibirsk (Russian Federation); Cheng, H.-H. [Center for Condensed Matter Sciences and Graduate Institute of Electronic Engineering, National Taiwan University, Taipei, 106, Taiwan, ROC (China)

    2014-04-30

    In situ reflection high energy electron diffraction was used to study the surface micromorphology of Si{sub x}Sn{sub y}Ge{sub 1−x−y} / Si(100) heterostructures obtained by molecular beam epitaxy. The obtained reflection high energy electron diffraction data allowed us to conclude that the epitaxial Si{sub x}Sn{sub y}Ge{sub 1−x−y} films are grown by the Stranski–Krastanov mechanism. It was established that Si{sub x}Sn{sub y}Ge{sub 1−x−y} and Ge{sub 1−z}Sn{sub z} wetting layer thicknesses depend on the substrate temperature. The observed surface superstructures changed during the wetting layer growth. - Highlights: • Stranski–Krastanov mechanism • Wetting layers depend on the temperature • Superstructures change.

  2. Electronic structure and magnetism of new scandium-based full Heusler compounds: Sc{sub 2}CoZ (Z = Si, Ge, Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Birsan, A., E-mail: anca_birsan@infim.ro

    2014-06-15

    Highlights: • First principles calculations were performed for Sc{sub 2}CoSi, Sc{sub 2}CoGe and Sc{sub 2}CoSn. • The total magnetic moments are 1μ{sub B}/f.u. at equilibrium lattice constants. • Sc{sub 2}CoSi is fully spin polarized for lattice parameters ranging between 6.21 and 6.56 Å. • Sc{sub 2}CoGe presents a pseudogap formed around Fermi level. • Sc{sub 2}CoSn exhibits a half metallic ferromagnetic character, up to 7.05 Å. - Abstract: First principles FPLAPW calculations were performed in the framework of Density Functional Theory (DFT), to study the electronic structures and magnetic properties for the new full-Heusler compounds: Sc{sub 2}CoZ (Z = Si, Ge, Sn). The investigated materials are stable against decomposition, in ferromagnetic configuration and crystallize in the inverse Heusler structures. The half-metallic properties as function of the variation of unit cell volumes are analysed regarding the fourth main group constituent elements. The electronic structure calculations for Sc{sub 2}CoSi and Sc{sub 2}CoSn show half-metallic characters, with indirect band gaps of 0.544 eV and 0.408 eV at optimised lattice parameters of 6.28 Å and 6.62 Å, respectively. For Sc{sub 2}CoGe compound, the Fermi energy is not pinned inside the energy band gap from minority density of states, neither for unit cell contraction nor for enlargement. The calculated total magnetic moments are 1μ{sub B}/f.u., for all compounds, in agreement with Slater–Pauling rule.

  3. Memory type switching behavior of ternary Ge20Te80-x Sn x (0  ⩽  x  ⩽  4) chalcogenide compounds

    Science.gov (United States)

    Jeevan Fernandes, Brian; Sridharan, Kishore; Munga, Pumlian; Ramesh, K.; Udayashankar, N. K.

    2016-07-01

    Chalcogenide compounds have gained huge research interest recently owing to their capability to transform from an amorphous to a crystalline phase with varying electrical properties. Such materials can be applied in building a new class of memories, such as phase-change memory and programmable metallization cells. Here we report the memory type electrical switching behavior of a ternary chalcogenide compound synthesized by doping Tin (Sn) in a germanium-telluride (Ge20Te80) host matrix, which yielded a composition of Ge20Te80-x Sn x (0  ⩽  x  ⩽  4). Results indicate a remarkable decrease in the threshold switching voltage (V T) from 140 to 61 V when the Sn concentration was increased stepwise, which is attributed to the domination of the metallicity factor leading to reduced amorphous network connectivity and rigidity. Variation in the threshold switching voltage (V T) was noticed even when the sample thickness and temperature were altered, confirming that the memory switching process is of thermal origin. Investigations using x-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed the formation of a crystalline channel that acts as the conduction path between the two electrodes in the switched region. Structural and morphological studies indicated that Sn metal remained as a micro inclusion in the matrix and hardly contributed to the rigid amorphous network formation in Ge20Te80-x Sn x . Memory type electrical switching observed in these ternary chalcogenide compounds synthesized herein can be explored further for the fabrication of phase-change memory devices.

  4. Superconductivity and crystal and electronic structures in hydrogenated and disordered Nb3Ge and Nb3Sn layers with A15 structure

    Science.gov (United States)

    Nölscher, C.; Saemann-Ischenko, G.

    1985-08-01

    Superconducting and transport properties of Nb3Ge and Nb3Sn layers have been varied over a wide range by hydrogenation, ion irradiation, and annealing. After hydrogenation, both compounds remain in the A15 structure and no effects of hydride precipitations at low temperatures could be observed. At high ion-irradiation doses Nb3Ge becomes amorphous, but Nb3Sn remains in the A15 structure, although Tc behaves similarly. The long-range order parameter SA and the mean displacement amplitude u2>1/2 were determined for Nb3Sn with x-ray diffraction. Distinct differences between the irradiation- and annealing-induced correlations of Tc versus Sa, Tc versus u2>, and Tc versus lattice parameter were observed. This indicates the influence of topological short-range order. The correlations of Tc versus residual resistivity and Tc versus the temperature derivative of the upper critical field at Tc are distinctly different for hydrogenated and irradiated Nb3Sn and Nb3Ge, but the derived correlations of Tc versus the coefficient of the electronic specific heat are very similar. The results are interpreted by a dominant influence of the Γ12 band on high Tc. The measurements of the Hall constant RH indicate a filling of steep electronic bands as a result of hydrogenation. Irradiation has a similar influence as thermal-induced disorder on RH. A maximum in the temperature dependence of RH indicates a martensitic transformation of Nb3Sn at 50-55 K, which is unchanged in slightly hydrogenated samples with higher Tc but vanishes in irradiated samples.

  5. Effect of Sb addition on linear and non-linear optical properties of amorphous Ge-Se-Sn thin films

    Science.gov (United States)

    Sharma, Navjeet; Sharma, Surbhi; Sarin, Amit; Kumar, Rajesh

    2016-01-01

    Optical characterization of amorphous thin films of Ge20Sn10Se70-xSbx (x = 0, 3, 6, 9, 12, 15) has been carried out. Thin films were deposited onto pre cleaned glass substrates using thermal evaporation technique. Transmission spectra of the films were recorded, for normal incidence, in range 400-2400 nm. Refractive index of the films was calculated using the envelope method by Swanepoel. Dispersion analysis has been carried out using single effective oscillator model. Other optical constants such as absorption coefficients, extinction coefficients have also been evaluated. Tauc plots were used to evaluate the optical band gap. The refractive index has been found to be increasing while the band gap decreases with increasing Sb concentration. The observed optical behavior of the films has been explained using chemical bond approach. Cohesive energy is found to be decreasing in the present work, which reflects that bond strength decreases with the increasing content of Sb. Non-linear optical parameters (i.e. n2 and χ(3)) have been derived from linear optical parameters (i.e. n, k, Eg). Observed changes in linear and non-linear parameters have been reported in this study.

  6. Electronic, optical and lattice dynamic properties of the novel diamond-like semiconductors Li2CdGeS4 and Li2CdSnS4

    Science.gov (United States)

    Li, Yanlu; Fan, Weiliu; Sun, Honggang; Cheng, Xiufeng; Li, Pan; Zhao, Xian

    2011-06-01

    Li2CdGeS4 and Li2CdSnS4 are novel quaternary diamond-like semiconductors (DLSs) which have been synthesized recently. We present first-principles calculations of their electronic, optical and lattice dynamic properties with the plane-wave pseudopotential method. We have found an indirect band gap of 2.78 eV for Li2CdGeS4 and a direct band gap of 2.50 eV for Li2CdSnS4. The serious stretching vibrations of the Ge/Sn-S and Li-S bonds may enhance their phonon energies, and cause them to exhibit high heat capacities and Debye temperatures, which are promising for nonlinear optical applications. Compared with Cu-based DLSs, Li plays a key role in enlarging the band gaps and increasing the lattice phonon energies, which would increase the thermal conductivity accompanied by an increase of the optical damage threshold.

  7. Na2 BaMQ4 (M=Ge, Sn; Q=S, Se): Infrared Nonlinear Optical Materials with Excellent Performances and that Undergo Structural Transformations.

    Science.gov (United States)

    Wu, Kui; Yang, Zhihua; Pan, Shilie

    2016-06-01

    Infrared nonlinear optical (IR NLO) materials with excellent performances are particularly important in laser technology. However, to design and synthesize an efficient IR NLO material with a balance between the optical band gap and the NLO coefficient is still a huge challenge. With this in mind, four new IR NLO materials Na2 BaSnS4 , Na2 BaSnSe4 , Na2 BaGeS4 , and Na2 BaGeSe4 were successfully designed and synthesized. The compounds exhibit excellent properties with a suitable balance of band gap and NLO coefficient measured for Na2 BaSnS4 (3.27 eV and about 17×KDP, that is, about 17 times that of KH2 PO4 (KDP)) and Na2 BaGeS4 (3.7 eV and about 10×KDP), demonstrating that the systems satisfy the key requirements as promising IR NLO candidates. Remarkably, the new compounds also undergo a novel structural transformation from tetragonal to trigonal systems, the first time that this has been reported for quaternary metal chalcogenides. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. First-principles study of new series of quaternary Heusler alloys CsSrCZ (Z=Si, Ge, Sn, P, As, and Sb)

    Science.gov (United States)

    Bouabça, A.; Rozale, H.; Amar, A.; Wang, X. T.; Sayade, A.; Chahed, A.

    2016-12-01

    The structural, electronic, magnetic, and thermal properties of new quaternary Heusler alloys CsSrCZ (Z=Si