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- Aberg, J, et al.
(author)
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Electrical properties of the TiSi2-Si transition region in contacts : The influence of an interposed layer of Nb
- 2001
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 90:5, s. 2380-2388
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Journal article (peer-reviewed)abstract
- The influence of an interposed ultrathin Nb layer between Ti and Si on the silicide formation and the electrical contact between the silicide formed and the Si substrate is investigated. The presence of the Nb interlayer results in the formation of ternary alloy (Nb,Ti)Si-2 in the C40 crystallographic structure adjacent to the Si substrate. Depending on the nature of the Si substrates and/or the amount of the initial Nb, the interfacial C40 (Nb,Ti)Si-2 leads, in turn, to either epitaxial growth of a highly faulted metastable C40 TiSi2 or formation of the desired C54 TiSi2 at a lower temperature than needed for it to form in reference samples with Ti deposited directly on Si. On p-type substrates doped to various concentrations, the Nb also leads to a considerably lower specific contact resistivity than that obtained in the reference samples: a twofold to fourfold reduction in the contact resistivity is found using cross-bridge Kelvin structures in combination with two-dimensional numerical simulation. As C40 (Nb,Ti)Si-2 forms at the interface when an interfacial Nb is present, the interface characterized is likely to represent the one between (Nb,Ti)Si-2 and Si. For the reference samples, the interface studied is between TiSi2 and Si.
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| 4. |
- Aberg, V., et al.
(author)
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Synthesis and absolute configuration of methyl(-)-(3R)-8-(4-bromophenyl)-7-(naphthalen-1-yl-methyl)-5-oxo-2,3-dihydro-5H-thiazolo 3,2-a pyridine-3-carboxylate
- 2002
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In: Acta Crystallographica Section E. - : International Union of Crystallography (IUCr). - 1600-5368. ; 58, s. o812-o814
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Journal article (peer-reviewed)abstract
- The title molecule, C26H20BrNO3S, contains a ring-fused 2-pyridinone framework substituted with a 4-bromo-phenyl-, a naphthalen-1-ylmethyl and a methoxycarbonyl substituent. The main goal of this work was to confirm the stereochemistry for the methoxycarbonyl substituent, which proved to be 3R. Moreover, the 4-bromophenyl substituent was shown to be rotated out of the plane of the 2-pyridinone ring, with a torsion angle of 61.2 (5)degrees. To allow the best packing arrangement, the naphthalen-1-ylmethyl substituent is positioned to mediate an intermolecular pi-pi interaction.
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| 9. |
- Schmitz, Birger, et al.
(author)
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Basaltic explosive volcanism, but no comet impact, at the Paleocene-Eocene boundary: high-resolution chemical and isotopic records from Egypt, Spain and Denmark
- 2004
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In: Earth and Planetary Science Letters. - : Elsevier BV. - 1385-013X .- 0012-821X. ; 225:1-2, s. 1-17
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Journal article (peer-reviewed)abstract
- In the search for a triggering mechanism for the Paleocene-Eocene (P-E) boundary event, 55 Ma, centimeter-resolution chemical (e.g., Ir, Os, Pt) and isotope (e.g., (OS)-O-187/Os-188, He-3/He-4, Sr-87/Sr-86) records across this boundary have been established for six uplifted marine sections in Egypt, Spain and Denmark. The sections studied represent some of the stratigraphically most complete records across the onset of the carbon isotopic excursion (CIE) and associated benthic foraminifera extinctions that mark the Paleocene-Eocene boundary. High-sensitivity analyses failed to uncover evidence of extraterrestrial element or isotope enrichments in the six sections, refuting the hypothesis of a major comet impact at the boundary. Preliminary searches for other impact-indicative features, such as spherules or shocked quartz, also gave negative results. In the Danish section studied, three basaltic Ir-rich ash layers occur at the Paleocene-Eocene boundary, but no similar ashes were found in Egypt or Spain. The three ashes represent the earliest known manifestation of an unusual I to 2 million year long phase of explosive basaltic volcanism in the Faero-Greenland region. This volcanism is synchronous with major flood basalt effusions in East Greenland and is associated with prominent paleogeographic changes in the high-latitude North Atlantic region. Discharge of mantle-derived Os to seawater during this volcanism may explain a small decrease in (OS)-O-187/(OS)-O-188 ratio at the Paleocene-Eocene boundary in the Zumaya section in Spain. The environmental perturbations at the Paleocene-Eocene boundary appear to have been triggered by basaltic volcanism, but any model for the detailed causal relation remains speculative. (C) 2004 Elsevier B.V. All rights reserved.
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