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  • 1
    Electronic Resource
    Electronic Resource
    Kinetic and equilibrium studies of halogen exchange on trivalent phosphorus (1972)
    s.l. : American Chemical Society
    Inorganic chemistry 11 (1972), S. 564-566 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic50109a028
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  • 2
    Electronic Resource
    Electronic Resource
    Role of vanadium in organometallic vapor phase epitaxy grown GaAs (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1772-1774 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical and photoluminescent properties of vanadium incorporated into GaAs epitaxial layers from a VO(OC2H5)3 source during organometallic vapor phase epitaxy were examined. The vanadium concentration in the GaAs was controllably varied from 1016 to 1018 atoms cm−3. Deep level transient spectroscopy showed the presence of an electron trap at Ec−0.15 eV which increased in concentration with vanadium content of the epitaxial layers. A maximum value of 8×1015 cm−3 for this trap was obtained. There were no midgap electron traps associated with vanadium. In intentionally Si-doped epitaxial layers, co-doping with vanadium was observed to have no effect in reducing the carrier density when the Si concentration was ≥4×1016 cm−3. The net carrier concentration profiles resulting from 29Si implantation into GaAs containing 1018 cm−3 of total V had sharper tails than for similar implantation into undoped material, indicating the presence of less than 1016 cm−3 V-related acceptors. Photoluminescent spectra exhibited the characteristic V+3 intracenter emission at 0.65–0.75 eV. No other deep level photoluminescence was detected. For a V concentration of 1016 cm−3 only 2.5×1013 cm−3 was electrically active. Over the entire V concentration investigated this impurity was predominantly (≥99%) inactive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101287
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  • 3
    Electronic Resource
    Electronic Resource
    Mechanisms of interdiffusion in copper/nickel thin-film couples (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 1147-1155 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Mechanisms of interdiffusion in copper/nickel thin-film couples have been investigated in the temperature interval 573–777 K by in situ measurement of contact resistance, Auger depth profiling (ADP), and transmission electron microscopy. Correlation between evolution of contact resistance and measured Auger concentration profiles has been established and mechanisms incorporating rapid grain boundary diffusion, followed by defect-assisted diffusion into grain interiors (Type B kinetics), are proposed to explain the accelerated reactions observed. A modified Whipple model and two independent methods, based on ADP and contact resistance measurements, are used to calculate grain boundary and intragranular diffusion coefficients, respectively. The calculated grain boundary diffusion coefficient is (0.82 cm2/s) exp(−1.48eV/kT) for nickel in copper, and approximately 4×10−13 cm2/s for copper in nickel at 673 K. An average intragranular diffusion coefficient for nickel in copper is determined to be (2.6×10−6 cm2/s) exp(−1.38 eV/kT) by both methods, whereas ADP data yield a corresponding value of (5.2×10−8 cm2/s) exp(−1.51eV/kT) for copper in nickel. It is concluded that characterization of chemical composition and microstructure, combined with in situ measurement of concomitant electrical properties, provides a reliable description of interdiffusion mechanisms in this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336552
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  • 4
    Electronic Resource
    Electronic Resource
    An analysis of dislocation reduction by impurity hardening in the liquid-encapsulated Czochralski growth of 〈111〉 InP (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 4383-4389 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Excessive impurity additions have been widely used to suppress dislocation generation in the liquid-encapsulated Czochralski (LEC) growth of InP. We have analyzed this approach by means of the quasi-steady-state heat transfer/thermal stress model. A strong motivation for the investigation was provided by the recent measurement of the critical resolved shear stress σCRS of InP as a function of temperature in the range 748–948 °K for several Ge and S concentrations. The experimental data were analyzed by the method of least squares via the usually accepted logarithmic dependence of σCRS on reciprocal temperature. The extrapolated values of σCRS exhibit a monotonic increase with impurity addition at temperatures near the melting point. Introducing the σCRS and realistic estimates of other physical properties (thermal diffusivity, thermal expansion coefficient, elastic constants, etc.) in the thermal stress model, the dislocation distribution pattern in a {111} substrate cut from a 〈111〉 boule was constructed. This necessitated a suitable recasting of the formalism that was previously applicable only to the {100} orientation. The computed dislocation contour maps on {111} wafers display sixfold symmetry resembling the "Star of David,'' in overall agreement with etch-pit patterns. InP crystals 2.5 cm in diameter grown in a standard high ambient temperature gradient but containing a large amount of Ge ((approximately-equal-to)1019 cm−3) are predicted and observed to be dislocation-free. On the other hand, in nominally undoped material a large density of defects is forecast, especially at the periphery, in line with the etchpit configuration. Intermediate doping levels (∼1017 cm−3 Ge, ∼1018 cm−3 S) reduce the density in the core but leave the outer edge essentially unaltered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335528
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  • 5
    Electronic Resource
    Electronic Resource
    Surface polygonization on GaAs wafers (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1468-1471 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polygonized surface structure produced by furnace annealing GaAs wafers was studied by optical and scanning electron microscopy. The surface structure was revealed by chemically etching wafers which had been implanted with silicon and subjected to a furnace annealing cycle. Cathodoluminescence micrographs demonstrate an absence of impurity segregation to the polygon boundaries. No correlation was found between growth-induced dislocations and the polygonal networks. It is proposed that the surface structure results from a vacancy-condensation process. Related surface effects were observed for rapidly annealed wafers. A correlation between the furnace annealed and rapidly annealed GaAs is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341819
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of mononuclear and dinuclear bis(2,2'-bipyridine)ruthenium(II) complexes containing sulfur-donor ligands (1989)
    s.l. : American Chemical Society
    Inorganic chemistry 28 (1989), S. 912-920 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic00304a023
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  • 7
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance investigation of exchange between chlorine and chloride ion in aqueous solution (1973)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 77 (1973), S. 2149-2153 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100636a024
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  • 8
    Electronic Resource
    Electronic Resource
    Liquid densities of trifluoromethyldichlorophosphine and trifluoromethyldibromophosphine (1971)
    s.l. : American Chemical Society
    Journal of chemical & engineering data 16 (1971), S. 411-412 
    Details
    ISSN: 1520-5134
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/je60051a006
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  • 9
    Electronic Resource
    Electronic Resource
    RIBONUCLEOTIDE REDUCTASES (1998)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biochemistry 67 (1998), S. 71-98 
    Details
    ISSN: 0066-4154
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Biology
    Notes: Abstract Ribonucleotide reductases provide the building blocks for DNA replication in all living cells. Three different classes of enzymes use protein free radicals to activate the substrate. Aerobic class I enzymes generate a tyrosyl radical with an iron-oxygen center and dioxygen, class II enzymes employ adenosylcobalamin, and the anaerobic class III enzymes generate a glycyl radical from S-adenosylmethionine and an iron-sulfur cluster. The X-ray structure of the class I Escherichia coli enzyme, including forms that bind substrate and allosteric effectors, confirms previous models of catalytic and allosteric mechanisms. This structure suggests considerable mobility of the protein during catalysis and, together with experiments involving site-directed mutants, suggests a mechanism for radical transfer from one subunit to the other. Despite large differences between the classes, common catalytic and allosteric mechanisms, as well as retention of critical residues in the protein sequence, suggest a similar tertiary structure and a common origin during evolution. One puzzling aspect is that some organisms contain the genes for several different reductases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.biochem.67.1.71
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  • 10
    Electronic Resource
    Electronic Resource
    FOSSIL ENERGY (1973)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 216 (1973), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1973.tb41368.x
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