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  • 1
    Electronic Resource
    Electronic Resource
    Kinetic Resolution of Pipecolic Acid Using Partially-Purified Lipase from Aspergillus niger (1994)
    s.l. : American Chemical Society
    The @journal of organic chemistry 59 (1994), S. 2075-2081 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00087a023
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  • 2
    Electronic Resource
    Electronic Resource
    Time-resolved reflection and transmission studies of amorphous Ge-Te thin-film crystallization (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2272-2282 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements of the temperature and time dependence of visible diode laser transmission and reflection are combined with transmission electron microscopy (TEM) to study the crystallization of two 75 nm Ge-Te thin films. Near-stoichiometric Ge48Te52 transforms by the rapid growth of crystals through the film thickness followed by 2D growth in the film plane. Changes in film reflection and transmission are directly related to the volume fraction transformed. The optical measurements are interpreted in terms of classical Johnson–Mehl–Avrami kinetics. A Kissinger analysis gives an activation energy for crystallization of 1.7 eV. Isothermal measurements lead to an Avrami exponent of 4.5. The data are modeled using a numerical temperature-dependent expression developed by Greer [Acta Metall. 30, 171 (1982)]. Off-stoichiometric Ge54Te46 films show markedly different crystallization behavior. Transmission and reflection measurements indicate that the transformation proceeds by rapid growth of a crystalline layer at the free surface of the film followed by 1D growth of this layer through the film. The observation is confirmed by TEM imaging and diffraction. This work shows that reflection and transmission measurements can be an effective method for the study of crystallization kinetics of amorphous thin films, particularly when more traditional calorimetric methods cannot be employed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353132
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  • 3
    Electronic Resource
    Electronic Resource
    A quick thermoelectric technique for typing HgCdTe at liquid nitrogen temperature (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 3636-3638 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A simple and quick technique based on thermoelectric effect of semiconductors has been developed for screening the conductivity type of narrow band-gap HgCdTe materials. This technique generates a temperature gradient across the sample by partly dipping it in liquid nitrogen. The induced Seebeck voltage is then measured by loading two spring contact probes to two separate points on the sample below and above the liquid nitrogen level. It was found, as expected by the theory, that the thermoelectric measurements on p-type HgCdTe are much less influenced by the inverted surface effects than Hall measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350926
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  • 4
    Electronic Resource
    Electronic Resource
    Observation of a deep level in p-type Hg0.78Cd0.22Te with high dislocation density (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5269-5271 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: To investigate the possibility that deep levels are associated with dislocations in narrow band gap HgCdTe, deep level transient spectroscopy has been used to study n+-p diodes fabricated on p-type bulk Hg0.78Cd0.22Te samples with either a "normal'' dislocation density of about 105 cm−2 or a high dislocation density of about 106 cm−2. These samples which are gold doped with a hole concentration of 1.2×1015 cm−3, have a band gap of about 0.12 eV at 77 K. In samples with a "normal'' dislocation density, a deep level of about 80 meV above the valence band was found. However, a midgap level of about 60 meV above the valence band with larger peak amplitude and broader line shapes was found in the sample with a high dislocation density.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350590
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  • 5
    Electronic Resource
    Electronic Resource
    Anomalous low-frequency butterfly curves for subsidiary and ferromagnetic resonance overlap at 3 GHz (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 1569-1573 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Subsidiary absorption butterfly curves of spin-wave instability threshold versus static in-plane field have been obtained for yttrium iron garnet (YIG) thin films at 3 GHz. The butterfly curves have been found to be rather anomalous, typically displaying a pronounced dip and a very low minimum threshold. These anomalous features are attributed to the overlap of the subsidiary absorption field region with ferromagnetic resonance (FMR). First-order instability theory was extended to include the uniform mode response near FMR. The extended theory yields good fits to the data for reasonable values of the YIG FMR linewidths. The theoretical analysis also shows a predicted flip in the azimuthal propagation angle φk for the unstable spin waves in the region of FMR overlap. With increasing field, there are predicted discontinuous changes in φk from 90° to 0° and back to 90° in the region of FMR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347251
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  • 6
    Electronic Resource
    Electronic Resource
    The majority carrier mobility of n-type and p-type Hg0.78Cd0.22Te liquid phase epitaxial films at 77 K (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2916-2920 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dependence of majority carrier mobility on carrier concentration at 77 K in Hg0.78Cd0.22Te has been studied by Hall measurements on about 190 n-type and 360 p-type liquid phase epitaxial films. The n-type films were indium doped with the carrier concentration varying from 1×1014 to 2×1016 cm−3. The measured electron mobility changed from 2×105 to 8×104 cm2/V s. The p-type films were undoped (Hg vacancy) with the carrier concentration varying from 2×1015 to 3×1017 cm−3. The measured hole mobility changed from 600 to 200 cm2/V s. By comparing calculated mobility curves with the experimental data, we found that the major scattering mechanisms for electron mobility in n-type materials were polar optical phonon, ionized impurity, and alloy disorder scatterings. These three scattering mechanisms also dominate the hole mobility in p-type materials at 77 K. It was also found that a model with Hg vacancy as doubly ionized shallow acceptors fitted very well the hole mobility versus carrier concentration data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353022
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  • 7
    Electronic Resource
    Electronic Resource
    Electrical and microstructural characteristics of Ti contacts on (001)Si (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2590-2597 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An investigation of the electrical and microstructural characteristics of the Ti contact on silicon has been carried out. The presence of As in Ti/n+-Si samples was found to retard the formation of polycrystalline silicide (p-silicide) compared with that in Ti/p+-Si samples with BF2+ implantation. Amorphous interlayers (a-interlayers) were found to be present in both Ti/n-Si and Ti/p-Si samples annealed at temperatures of and lower than 450 °C. Although the Schottky barrier heights (SBH's) vary for about 0.05–0.08 eV for samples annealed over a temperature range from room temperature to 900 °C, SBH's at the a-interlayer/n-Si and a-interlayer/p-Si were measured to be about 0.52–0.54 and 0.59–0.57 eV, respectively. The specific contact resistance (ρc) in the Ti/n+-Si system was measured to be the lowest with a value of 1.4×10−7 Ω cm2 when the a interlayer is present. In Ti/p+-Si system, the minimum ρc is about 3×10−7 Ω cm2. The variation in contact resistance with annealing temperature for both Ti/n+-Si and Ti/p+-Si samples is correlated to the change in dopant concentration beneath the contacts as well as microstructures. In the temperature regime where the a interlayer is in contact with the silicon substrate, the junction diode leakage current densities (Jleak's) are considerably lower than those in samples annealed at higher temperatures. The Jleak at −6 V reverse bias is lower than 1 nA/cm2. The breakdown voltage is about 14 V (16 V) for the n+/p (p+/n) junction. The thickness of consumed Si is less in samples annealed at low temperature, and the a-interlayer/Si or p-silicide/Si interface is accordingly farther away from the junction as well as the end-of-range defects. The interface of p-silicide/Si is rougher than that of a-interlayer/Si. In addition, the roughness of the p-silicide/Si interface increases with annealing temperature. For both p+/n and n+/p junctions annealed at 900 °C, rough p-silicide/Si interfaces are thought to lead to spiking and increase the leakage currents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354672
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  • 8
    Electronic Resource
    Electronic Resource
    Minority-carrier lifetime in indium-doped n-type Hg0.78Cd0.22Te liquid-phase-epitaxial films (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 4761-4766 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The recombination mechanisms of the minority-carrier lifetime in n-type indium-doped Hg0.78Cd0.22Te liquid-phase-epitaxial films have been studied. Its temperature dependence was measured from 78 to 200 K using standard photoconductivity decay method. The dependence on doping concentration from 1×1014 to 2×1015 cm−3 was measured using a contactless microwave reflection method at 77 K. From best fits to the experimental temperature dependence data, it was found that lifetimes at temperatures higher than 130 K were dominated by Auger recombination with a value of 0.15 for the overlap integral of Bloch functions. For most films with a doping concentration below 1×1015 cm−3, Shockley–Read–Hall recombination via an acceptor-like deep level at about 40 meV below the conduction band affected lifetimes below 120 K. It was also found that the recombination parameters determined from fitting the lifetime versus temperature curves were adequate to analyze and understand the lifetime versus doping concentration curve, which comprised data from over 100 films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352087
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  • 9
    Electronic Resource
    Electronic Resource
    Partitioning behavior of Al in a nanocrystalline FeZrBAl soft magnetic alloy (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 439-442 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Atom probe field ion microscopy was employed to investigate the distribution of Al in a nanocrystalline Fe88Zr7B3Al2 soft magnet with optimal magnetic performance. The atom probe concentration depth profiles show that the Al atoms preferentially partition into the residual amorphous phase, and the partitioning factor of Al is approximately five times larger in the amorphous phase than in the bcc Fe phase. Based on the experimental results, the beneficial effect of the addition of Al on the soft magnetic properties is attributed to the change of the inherent magnetostriction constant of the residual amorphous phase induced by Al partitioning. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371881
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  • 10
    Electronic Resource
    Electronic Resource
    On the thermodynamic solution of the Boltzmann equation and nonlinear irreversible thermodynamics (1989)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 30 (1989), S. 1329-1337 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: Based on the results of a previous paper on the thermodynamic solution of the Boltzmann equation, some important questions in nonlinear irreversible thermodynamics are reexamined; specifically, the Gibbs relations, the Onsager relations, and the relationship between thermodynamic stability in terms of the entropy balance equation and the dynamical stability of the hydrodynamic equations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.528313
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