| 1. |
- Soderstrom, D., et al.
(författare)
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Dopant diffusion and current-voltage studies on epitaxial InP codoped with Ru and Fe
- 2001
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Ingår i: Journal of Electronic Materials. - 0361-5235 .- 1543-186X. ; 30:8, s. 972-976
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Tidskriftsartikel (refereegranskat)abstract
- Semi-insulating Fe and Ru codoped InP epitaxial layers grown by low-pressure hydride vapor phase epitaxy have been investigated. InP:Ru and InP:Fe,Ru layers were grown on p-InP:Zn and n-InP:S substrates, in order to study dopant diffusion and electrical characteristics. Dopant diffusion profiles of Ru, Fe and Zn were measured by secondary ion mass spectroscopy. A small but noteworthy diffusion front is observed when InP:Ru is adjacent to InP:Zn, but not when adjacent to n-InP. For InP:Fe codoped with Ru a pronounced interdiffusion of Fe and Zn is observed for Ru concentrations less than 2 X 10(17) cm(-3), but, for a higher Ru concentration the interdiffusion is clearly suppressed. Moreover, when InP is codoped with Fe and Ru, the small diffusion tail of Ru in InP:Zn vanishes. Unlike InP:Fe, resistivities above 1 X 10(8) Ohm cm are measured for both electron and hole-current injection in InP:Fe,Ru.
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| 2. |
- Soderstrom, D., et al.
(författare)
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Electrical characterization of ruthenium-doped InP grown by low pressure hydride vapor phase epitaxy
- 2001
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Ingår i: Electrochemical and solid-state letters. - 1099-0062 .- 1944-8775. ; 4:6, s. G53-G55
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial layers of ruthenium-doped InP grown by low-pressure hydride vapor phase epitaxy have been studied. Current voltage measurements were conducted at temperatures between 20 and 200 degreesC for samples doped with Ru in the range 1 x 10(17) to 5 X 10(17) cm(-3). In this doping range, the specific resistivity of n(+)/InP:Ru/n(+) structures accommodating electron injection is less than or equal to1 x 10(4) Ohm cm and that of p(+)/InP:Ru/p(+) structures accommodating hole injection is as high as 3 x 10(10) Ohm cm. The reason for such a huge difference in the resistivity of these structures is attributed to a low activation of deep Ru acceptors, thus rather giving rise to an n(-) layer than a semi-insulating layer, as supported by our theoretical simulation. Analysis of the Arrhenius plots constructed from the temperature-dependent I-V curves yield an average activation energy of Ru with reference to the conduction band equal to 0.44 and 0.52 eV under electron and hole injection, respectively.
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| 3. |
- Soderstrom, D., et al.
(författare)
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Studies on ruthenium-doped InP growth by low-pressure hydride vapor-phase epitaxy
- 2001
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 148:7, s. G375-G378
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Tidskriftsartikel (refereegranskat)abstract
- Ruthenium-doped InP (InP:Ru) has been grown by low-pressure hydride vapor-phase epitaxy (LP-HVPE) using bis(eta (5)-2,4-dimethylpentadienyl)ruthenium(II) as precursor. Ruthenium concentrations in the range 2 x 10(15) to 2 x 10(18) cm(-3) have been achieved. The Ru incorporation has been studied in terms of incorporation flux, and it is shown that the growth rate limits: the incorporation rate. From current-voltage measurements on n-InP/InP:Ru/n-InP and p-InP/InP:Ru/p-InP structures, resistivities greater than 10(3) Omega cm and greater than 10(10) Omega cm have been obtained, respectively.
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| 4. |
- Collins, Matthew D., et al.
(författare)
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Arsenicicoccus bolidensis gen. nov., sp nov., a novel actinomycete isolated from contaminated lake sediment
- 2004
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Ingår i: INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY. - : Microbiology Society. - 1466-5026 .- 1466-5034. ; 54, s. 605-608
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Tidskriftsartikel (refereegranskat)abstract
- An unknown Gram-positive, catalase-positive, facultatively anaerobic, non-spore-forming, coccus-shaped bacterium originating from sediment was characterized using phenotypic, molecular chemical and molecular phylogenetic methods. Chemical studies revealed the presence of a cell-wall murein based on ll-diaminopimelic acid (type ll-Dpm-glycine1), a complex mixture of saturated, monounsaturated and iso- and anteiso-methyl-branched, non-hydroxylated, long-chain cellular fatty acids and tetrahydrogenated menaquinones with eight isoprene units [MK-8(H4)] as the major respiratory lipoquinone. This combination of characteristics somewhat resembled members of the suborder Micrococcineae, but did not correspond to any currently described species. Comparative 16S rRNA gene sequencing confirmed that the unidentified coccus-shaped organism is a member of the Actinobacteria and represents a hitherto-unknown subline related to, albeit different from, a number of taxa including Intrasporangium, Janibacter, Terrabacter, Terracoccus and Ornithinicoccus. Based on phenotypic and phylogenetic considerations, it is proposed that the unknown bacterium originating from lake sediment be classified as a new genus and species, Arsenicicoccus bolidensis gen. nov., sp. nov. (type strain CCUG 47306T=DSM 15745T).
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| 5. |
- Formicola, A, et al.
(författare)
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Astrophysical S-factor of 14N(p,γ)15O
- 2004
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 591:1-2, s. 61-68
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Tidskriftsartikel (refereegranskat)abstract
- We report on a new measurement of the 14N(p,γ) 15O capture cross section at Ep=140 to 400 keV using the 400 kV LUNA accelerator facility at the Laboratori Nazionali del Gran Sasso (LNGS). The uncertainties have been reduced with respect to previous measurements and their analysis. We have analyzed the data using the R-matrix method and we find that the ground state transition accounts for about 15% of the total S-factor. The main contribution to the S-factor is given by the transition to the 6.79 MeV state. We find a total S(0)=1.7±0.2 keVb, in agreement with recent extrapolations. The result has important consequences for the solar neutrino spectrum as well as for the age of globular clusters. © 2004 Elsevier B.V. All rights reserved.
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| 6. |
- Hoyles, Lesley, et al.
(författare)
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Jeotgalicoccus pinnipedialis sp nov., from a southern elephant seal (Mirounga leonina)
- 2004
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Ingår i: INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY. - : Microbiology Society. - 1466-5026 .- 1466-5034. ; 54, s. 745-748
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Tidskriftsartikel (refereegranskat)abstract
- A previously unknown Gram-positive, catalase-positive, facultatively anaerobic, non-spore-forming, coccus-shaped bacterium (A/G14/99/10T), originating from the mouth of a female southern elephant seal, was subjected to a taxonomic analysis. Comparative 16S rRNA gene-sequencing showed that the organism formed a hitherto unknown subline within the catalase-positive, low-G+C, Gram-positive cocci, exhibiting a specific association with species of the genus Jeotgalicoccus. Sequence divergence values of approximately 7 %, together with phenotypic differences, showed the unknown bacterium to be distinct from the two described species of this genus, Jeotgalicoccus halotolerans and Jeotgalicoccus psychrophilus. Based on phenotypic and phylogenetic considerations, it is proposed that strain A/G14/99/10T=CCUG 42722T=CIP 107946T from the mouth of a seal be classified as the type strain of a novel species of the genus Jeotgalicoccus, Jeotgalicoccus pinnipedialis sp. nov.
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| 7. |
- Imbriani, G., et al.
(författare)
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The bottleneck of CNO burning and the age of Globular Clusters
- 2004
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 420:2, s. 625-629
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Tidskriftsartikel (refereegranskat)abstract
- The transition between the Main Sequence and the Red Giant Branch in low mass stars is powered by the onset of CNO burning, whose bottleneck is 14N(p, γ) 15O. The LUNA collaboration has recently improved the low energy measurements of the cross section of this key reaction. We analyse the impact of the revised reaction rate on the estimate of the Globular Cluster ages, as derived from the turnoff luminosity. We found that the age of the oldest Globular Clusters should be increased by about 0.7-1 Gyr with respect to the current estimates.
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