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  • 1
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    The @journal of organic chemistry 49 (1984), S. 3498-3503 
    ISSN: 1520-6904
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5353-5356 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The thermal conductivity of thick-film diamond prepared by chemical vapor deposition (CVD) has been measured with heat flowing in a direction perpendicular to the plane of the film. A laser flash technique with fast infrared detection has been devised for measurement of thin samples with high conductivity. The conductivity perpendicular to the plane is observed to be at least 50% greater than with heat flowing parallel to the plane. This anisotropy is attributed to low-quality grain boundaries in the columnar microstructure. The observed dependence of the thermal conductivity on microstructure has important implications for thermal management of microelectronic devices with CVD diamond.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2886-2891 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Ceramic coatings of zirconium nitride have been fabricated on nickel, silicon, and M2 high-speed steel by methods of reactive magnetron sputtering ion plating (RMSP) and the dynamic ion mixing (DIM). The microhardness values of ZrN film prepared by RMSP with different nitrogen partial pressure have been discussed. The scratch tests provide that the adhesion of ZrN film produced by dynamic ion mixing is better than that by reactive magnetron sputtering ion plating. Auger electron spectroscopy analysis is used to analyze the composition distribution of ZrN film prepared by DIM and indicates that there is a transitional layer between the ZrN film and substrate. Meanwhile, by cross-sectional and the plan-view transmission electron microscopy, it is observed that the interlayer of amorphous structure exists in the interface zone between ZrN film and substrate. According to the analysis of energy-dispersive x-ray analysis patterns, the composition of this amorphous region fabricated by RMSP is Ni51Zr49 (≈NiZr), as is that fabricated by DIM. (Up to now it has not been reported that the amorphous transitional layer occurs in reactive magnetron sputtering ion plating). The reason why the adhesion of coating by DIM is better than that by RMSP is not the formation of the transitional layer in ion-beam-assisted deposition but the particle bombardment effects on the bulk of the thin film.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 536-538 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Having been exposed to hydrogen plasma, Te-doped GaAs wafers were deposited with metal Ti, to form Ti/n-GaAs Schottky barrier diodes (SBD). It was found that due to hydrogenation the Schottky barrier height (SBH) of the SBD decreases from 0.76 to 0.58 eV and the effective Richardson constant A** decreases from 11 to 0.03 A/cm2/K2. Annealing the hydrogenated SBD at different reverse biases at 100 °C produces SBHs that have a one-to-one correlation with the biases of reverse-bias annealing (RBA), i.e., the SBH can be controlled, within the range 0.58–0.74 eV, by the bias of RBA. When the reverse bias is equal to or larger than 3 V, the SBH and the effective Richardson constant of the hydrogenated SBDs after RBA are very near to those of SBDs without hydrogenation. This means that a RBA with a bias higher than a critical value, 3 V in our case, can remove the effects of hydrogenation, but if the SBD is annealed again without a bias at 100 °C for 1 h or more, its SBH and effective Richardson constant recover their hydrogenated values. The main experimental facts can be explained qualitatively by a simple theoretical model.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6510-6512 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: High transport Jc is essential for major bulk applications of the high-Tc superconductors. In this paper, we report transport critical current and magnetization behavior in c-axis textured Bi-Pb-Sr-Ca-Cu-O superconductor ribbons. The highly oriented layer structure was achieved by a combination processing of spray coating on silver foil, cold rolling, and partial melting. Transport Jc values as high as 2.3 × 105 A/cm2 at 4.2 K, H=8 T (H⊥ab) have been obtained, which is one of the highest reported so far. The high Jc at H≥ (R18)5 T is maintained to temperatures near 20 K. A comparison of Jc (transport) and Jc (magnetization) indicates that the size scale of the circulating supercurrent loop in the Bean model nearly corresponds to the whole sample dimension rather than the orders-of-magnitude-smaller grain size, thus demonstrating that the a-b grain boundaries in the melt-processed ribbons are not weak links. A similar bulk processing technique with more extensive deformation can also be used to produce weak-link-free thin films, as demonstrated by preparation of ∼3000-A(ring)-thick films. Since epitaxial growth from single crystal substrates is not required, the technique may be suitable for high-speed, low-cost production of large area thin films.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6247-6249 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Single-phase Fe4N and (Fe1−xNix)4N compounds have been synthesized in a continuous form by heat treating iron and iron-nickel alloy sheets at various temperatures under NH3/H2 atmospheres. The Fe4N sheet has a high room-temperature magnetization value of 179 emu/g (2.14 μB/Fe), which is only slightly less than 218 emu/g (2.19 μB/Fe) observed in pure iron. The magnetic moments of the Fe-Ni alloy nitrides decreased monotonically as x was increased, in contrast to those for the starting alloys Fe1−xNix which exhibited a peak value around x=0.05. The decrease in magnetic moment with nickel content in the alloy nitrides was close to the value anticipated by magnetic dilution from nickel. The coercive force is about 5 Oe and is slightly decreased by the Ni substitution. The Fe-nitride offers a significantly improved corrosion resistance over pure iron. Even further improvement is obtained in the (Fe1−xNix)4N system with only slight sacrifice in magnetic moment. The addition of nickel has been found to noticeably improve the mechanical ductility of the normally brittle Fe4N compound. Theses nitrides also exhibit significantly increased electrical resistivity and wear resistance, and may be useful for a variety of technological applications.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 4075-4078 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The fundamental relationship between excitonic photoluminescence (PL) intensity and excitation intensity in semiconductor quantum well structures is developed. This relationship is further simplified in the regime of low excitation, and used for a fit function of the Arrhenius plot of time-integrated PL intensity. The proposed four fit parameters are definitely correlated to the distinct characteristic quantities of the sample material, which are the binding energy of excitons, the activation energy, the scattering time, and the background concentration in the well. The validity of the model has been confirmed using our experiments. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 5474-5479 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The thermomechanical behavior of multilayer structures is a subject of perennial interest. Stoney's formula has long been one of the most important tools for understanding thermomechanical stress for single-layered structures like spin-coated polyimides or deposited metal thin film on substrates. In today's microelectronics, however, as multilayer substrates have become widely available, the "modified version" of Stoney's formula for multilayer applications is not only useful but necessary. While the majority of reports in the literature have focused on single-layer analysis, in this study, we examined an extended usage of Stoney's formula for multilayer analysis. A simple model, the multilayer-modified Stoney's formula, which predicts the stress contribution of each individual layer is proposed and verified through experiments and numerical analysis. Using various kinds of materials employed in a typical lamination-based multichip module technology, the thermomechanical behavior of the lamination-based multilayer substrates was measured by a laser profilometry during thermal cycling. The measured values were compared with calculated values using the multilayer-modified Stoney's formula. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 6929-6933 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A colossal magnetoresistance effect with more than a thousandfold change in resistivity (ΔR/RH=127 000% at 77 K, H=6 T) has been obtained in epitaxially grown La-Ca-Mn-O thin films. The effect is negative and isotropic with respect to the field orientations. The magnetoresistance is strongly temperature dependent, and exhibits a sharp peak that can be shifted to near room temperature by adjusting processing parameters. Near-room-temperature ΔR/RH values of ∼1300% at 260 K and ∼400% at 280 K have been observed. The presence of grain boundaries appears to be detrimental to achieving very large magnetoresistance in the lanthanum manganite films. The orders of magnitude change in electrical resistivity could be useful for various magnetic and electric device applications.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6915-6917 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Giant magnetoresistance in a spinodally decomposed, bulk 60 Cu-20 Ni-20 Fe alloy is reported. An annealed, quenched, and heat-treated sample with a compositional modulation of (approximately-less-than)50 A(ring) size exhibits a ΔR/R value as high as 9% at 4.2 K. Optimization of the ferromagnetic phase particle geometry through a combination of spinodal decomposition and uniaxial deformation led to a locally multilayered, superlattice-like structure and a dramatic increase in room-temperature magnetoresistance from ∼0.6 to ∼5%. This improvement in magnetoresistance is accompanied by a decrease in coercivity from ∼620 Oe in the fully decomposed material to ∼45 Oe in the optimized structure. Interestingly, this structure no longer exhibits the commonly observed temperature-dependent behavior of ΔR/R increasing at low temperatures, but rather shows a decrease at 4.2 K.
    Materialart: Digitale Medien
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