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  • 1
    Electronic Resource
    Electronic Resource
    Electrical characterization, metallurgical investigation, and thermal stability studies of (Pd, Ti, Au)-based ohmic contacts (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 2437-2444 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Although Pd/Ti/Pd/Au contacts are similar to their Pt/Ti/Pt/Au counterparts in providing low specific contact resistance, ρc, the former exhibits long-term thermal stability. Their projected mean times to 50% increase in ρc(μ50) at 150 °C to p+-GaAs (≥3.43×1015 h) are higher than those of the latter by over five orders of magnitude. Contacts to p+-In0.53Ga0.47As are not as thermally stable, with a much lower albeit respectable μ50 at 150 °C of ≥2.25×105 h. Contacts with an interfacial Pd layer provide ρc's that are at least two times lower than those without, and the presence of an oxide layer (GaxTiyOz) at the Ti/GaAs interface is identified as a possible cause. Pd–Ga–As phases are formed at the Pd/GaAs interface, being As-rich (PdxGayAs) initially and convert to Ga-rich phases (PduGavAs) upon a high temperature anneal and the eventual composition depends on the evaporated interfacial Pd thickness and annealing conditions. This could probably explain the existence of an optimum interfacial Pd layer thickness of 100 Å for achieving the lowest ρc. The Ga-rich PduGavAs phases formed are inferred to cause the liberation of As atoms from the GaAs lattice, thus enabling them to diffuse out to the Ti and react to form TixAsy phases that bind the As from further out-diffusion. This has in turn led to the accumulation of As at the Pd/Ti interface. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372198
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  • 2
    Electronic Resource
    Electronic Resource
    Sudden structural change at an air/binary liquid interface: Sum frequency study of the air/acetonitrile–water interface (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 5099-5101 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report the first observation of a sharp structural change in an air/acetonitrile–water interface as the solution composition varies; the abruptness of which suggests an interfacial phase transition. The structural change is manifested by shifts in the frequency and in the polarization of the signal from the acetonitrile molecules in the interface observed using infrared+visible surface sum frequency generation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464933
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and reactivity of Fe nanoparticles embedded in a semi-insulating matrix (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 7213-7217 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The technique of plasma enhanced chemical vapor deposition has been used to synthesize Fe nanoparticles in an amorphous boron carbide matrix. The nanoparticles range in size from approximately 0.7 to 4.5 nm. It has been demonstrated that the size of the nanoparticles is proportional to the density of the Fe precursor (ferrocene) in the vapor. The matrix films have been found to be extremely hygroscopic. Upon absorption of moisture the films buckle and delaminate from the Si substrate. The buckling is a consequence of induced strain arising from the transformation of the Fe nanoparticles into α-Fe2O3. The formation of α-Fe2O3 has been verified by electron diffraction and near edge x-ray absorption fine structure measurements. Examination of the magnetic properties of the α-Fe2O3 using the technique of magnetic circular dichroism indicate that the nanoparticles are not ferromagnetic. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372971
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  • 4
    Electronic Resource
    Electronic Resource
    Electrical characterization and metallurgical analysis of Pd-containing multilayer contacts on GaN (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 1242-1249 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ti(250 Å)/Al(2200 Å)/Pd(600 Å)/Au(1600 Å) contact on aqua-regia surface treated n-GaN (Si∼1.0×1019 cm−3) has yielded a minimum specific contact resistance (ρc) of 4.21×10−8 Ω cm2, achieved after thermal annealing at 500 °C for 8 min. This is superior to the most common n-GaN contact, Ti/Al, which has also been studied in the current work and produced a lowest ρc of 4.63×10−6 Ω cm2, obtained after annealing at 700 °C for 2 min. The long-term thermal stability analysis has also revealed that the Ti/Al/Pd/Au contact is more stable than Ti/Al on n-GaN. The projected mean time to 50% increase in ρc(μ50) at 150 °C for the former is 1.22×1012 h, which is higher by about three orders of magnitude than that of the latter at 3.54×109 h. Pd(200 Å)/Ni(300 Å)/Au(2000 Å) contact on boiling aqua-regia surface treated p-GaN (Mg∼1.0×1018 cm−3) has also been investigated and demonstrated a reasonable ohmic behavior with a ρc of 5.03×10−4 Ω cm2 after thermal annealing at 450 °C for 2 min. However, its thermal stability is mediocre with μ50 at 150 °C of only 1.49×103 h. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1383977
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  • 5
    Electronic Resource
    Electronic Resource
    The thermal refractive index coefficients of 7.5 mol % Nb:KTiOPO4 crystals (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 3516-3518 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The principal refractive indices and thermal refractive index coefficients for Nb:KTiOPO4 (KTP) crystal grown by the top-seed flux method from a starting material containing 7.5 mol % Nb have been measured using the autocollimation method. Using measurements made at wavelengths of 0.53975, 0.6328, 1.0795, and 1.3414 μm, in the temperature range from ambient to 188 °C, it is possible to determine the constants of the Sellmeier equations and the thermal refractive index coefficients as a function of wavelength. Also, the temperature acceptance bandwidth at 90° second harmonic generation noncritical phase matching direction was calculated. Comparison of these results with those for undoped KTiOPO4 [K. Rato, IEEE J. Quantum Electron QE-28, 1974 (1992)] and KNbO3 [B. Zysset, I. Biaggo, and P. Gunter, J. Opt. Soc. Am. B 9, 380 (1992)] implies that Nb-doped KTP crystals are suitable for blue coherent light devices. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371251
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  • 6
    Electronic Resource
    Electronic Resource
    External electro-optic measurement utilizing poled polymer-based asymmetric Fabry–Perot reflection film (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 6184-6188 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An external linear electro-optic measuring system based on a poled polymer asymmetric Fabry–Perot multiple reflection film has been built, and the electric signals propagating on an indium tin oxide coplanar strip transmission line have been successfully measured. The nonlinear polymer spin coated on the high-reflectivity glass substrate was corona poled, thus an asymmetric Fabry–Perot film was fabricated based on polymer reflectivity and high reflectivity glass. The film standing-free technique and reflective configuration were adopted in this system. The principle of the system was analyzed by multiple reflection and index ellipsoid methods. The voltage sensitivity about 5 mv/Hz was obtained as 1 kHz sine input electric signals propagating on coplanar electrodes. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371672
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  • 7
    Electronic Resource
    Electronic Resource
    A novel and sensitive Faraday-type magnetometer for the field range from 0 to 12 T (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 3755-3760 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A Faraday-type magnetometer is described in which the magnetic force is measured capacitively by monitoring the displacement of a spring-suspended quartz sample holder. A double gradient coil is used in order to compensate the force on the empty sample holder, thus minimizing the background signal. The magnetometer can be used at any temperature down to 1.4 K and has an ultimate sensitivity for magnetic moments of 2×10−6emu (G cm3).© 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148022
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  • 8
    Electronic Resource
    Electronic Resource
    Acoustic wave velocities in ceramics and other materials measured by a broadband goniometric method (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1271-1273 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article describes an economical short-pulse ultrasound system with a goniometer stage, with which both compression and shear wave reverberations in thin ceramic or other material samples may be separately time resolved. Arrival times of individual reverberations are compared to estimates made by computer simulation of the wave system by means of a parameter fitting routine. The system output gives compression and shear velocities based on several reverberations in the test material. Wide frequency bandwidths are achieved by using acoustically thick PZT transducers in time intervals less than one half period of their fundamental compression wave frequency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144078
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  • 9
    Electronic Resource
    Electronic Resource
    R-Deprenyl and R-2-Heptyl-N-Methylpropargylamine Prevent Apoptosis in Cerebellar Granule Neurons Induced by Cytosine Arabinoside but Not Low Extracellular Potassium (1998)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 70 (1998), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: R-Deprenyl and R-2-heptyl-N-methylpropargylamine (R-2-HMP) are compounds that have been shown to reduce neuronal death in various in vitro and in vivo models involving apoptosis but do not always prevent apoptosis. In the present study we have examined the effects of these compounds and their S enantiomers on cytosine arabinoside (ara C)-induced apoptosis and low K+-induced apoptosis in cerebellar granule cells in primary culture. It was found that R-deprenyl and R-2-HMP could prevent ara C-induced apoptosis with an EC50 around 10−9M but could not prevent low K+-induced apoptosis. S-Deprenyl and S-2-HMP did not prevent apoptosis under any conditions but were found to antagonize the antiapoptotic actions of R-deprenyl and R-2-HMP. Using the fluorescent mitochondrial dye chloromethyltetramethylrhodamine methyl ester it was found that there was a loss of mitochondrial function in cerebellar granule cells exposed to ara C but not low K+ medium. R-Deprenyl and R-2-HMP prevented the ara C-induced loss of mitochondrial function. It is concluded that R-deprenyl and R-2-HMP prevent apoptosis of cerebellar granule cells by a mechanism that is independent of monoamine oxidase inhibition and that they act on the same site to prevent specifically apoptosis involving a loss of mitochondrial membrane potential, possibly p53-dependent apoptosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1998.70020515.x
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  • 10
    Electronic Resource
    Electronic Resource
    Magnetic properties of Pr2Co17−xAlx compounds : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 5115-5117 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetic properties of Pr2Co17−xAlx compounds with 0≤x≤4 were studied by means of magnetic measurements. From these measurements it is derived that there is an almost linear decrease of the Curie temperature with Al concentration accompanied by a somewhat less strong decrease of the saturation moment at 5 K. For the compounds with 2≤x≤4, we have observed spin-reorientation transitions at temperatures that decrease strongly with increasing Al concentration. These spin-reorientations are interpreted as originating from a competition between the Pr- and Co-sublattice anisotropies. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365140
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