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  • 1
    Electronic Resource
    Electronic Resource
    Slow-time-scale magnetic fields driven by fast-time-scale waves in an underdense relativistic Vlasov plasma (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 321-328 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Slow-time-scale magnetic fields driven by fast-time-scale electromagnetic waves or plasma waves are examined from the perspective of the Vlasov–Maxwell equations for a relativistic Vlasov plasma. An equation for slow-time-scale magnetic field is obtained. The field proposed in the present paper is a result of wave–wave beating which drives a solenoidal current. The magnitude of the slow-time-scale magnetic field proposed here can be as high as 20 MG at the critical surface for a laser intensity I=1018 W/cm2 at wavelength λ0=1.05 μm. The predicted magnetic field is observed in two-dimensional particle simulations presented here. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1330200
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  • 2
    Electronic Resource
    Electronic Resource
    Theoretical investigation of minority carrier leakages of high-power 0.8 μm InGaAsP/InGaP/GaAs laser diodes (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2260-2262 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a theoretical model that accurately describes the effects of minority carrier leakage from the InGaAsP waveguide into InGaP cladding layers in high-power aluminum-free 0.8 μm InGaAsP/InGaP/GaAs separate confinement heterostructure lasers. Current leakage due to the relatively low band-gap discontinuity between the active region and the InGaP barrier can be eliminated by employing laser diodes with cavity length longer than 500 μm. Experimental results for lasers grown by low-pressure metalorganic chemical vapor deposition are in excellent agreement with the theoretical model. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112738
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  • 3
    Electronic Resource
    Electronic Resource
    Local stoichiometry measurement of Y-Ba-Cu-O thin layers grown by metal organic chemical vapor deposition (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 4092-4096 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Y-Ba-Cu-O thin films with different stoichiometry were grown by metal organic chemical vapor deposition on MgO and SrTiO3. The samples showed superconducting behavior in a wide range of average stoichiometry. However, energy dispersive x-ray spectroscopy (EDX) measurements show that best results can be obtained only in a small stoichiometry range. Critical temperatures of Tc(approximately-greater-than)89 K and critical current densities of jc (77 K)(approximately-greater-than)2×106 A/cm2 could be obtained with optimized stoichiometry. Spatially resolved EDX measurements show that copper tends to form precipitates on the layers if its average content exceeds 50 mol %, while yttrium is incorporated into the matrix if offered in excess.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355987
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  • 4
    Electronic Resource
    Electronic Resource
    Frequency dependence of the transverse biased permeability in thin permalloy films : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5995-5997 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The frequency dependence of the transverse biased permeability μ't(f ) has been measured up to 250 MHz in thin (0.044 μm) and thick (2.1 μm) unpatterned sputtered permalloy films with uniaxial anisotropy. In these films, the initial permeability along the hard axis can be described by the classical eddy current damping model assuming uniform rotation. For both films, μ't at low frequency agrees reasonably well with Hoffman's ripple model assuming appropriate values for the structure factor. In the thin film, μ't(f ) is independent of frequency within experimental error up to at least 250 MHz. However, in the thick film μ't(f ) decreases more rapidly with frequency than can be explained by classical eddy currents, when the transverse bias field HB is not very large compared to the net anisotropy field. The value of HB at which μ't(f ) reaches a maximum amplitude is also found to increase monotonically with increasing frequency, also inconsistent with simple eddy current predictions. It is suggested that the formation of ripple walls leads to anomalous eddy current losses similar to that observed in bulk materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353498
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  • 5
    Electronic Resource
    Electronic Resource
    p-doped GaAs/Ga0.51In0.49P quantum well intersub-band photodetectors (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 2126-2128 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Lattice-matched p-doped GaAs–Ga0.51In0.49P quantum well intersub-band photodetectors with three different well widths have been grown on GaAs substrates by metal-organic chemical-vapor deposition and fabricated into mesa structures. The photoresponse cutoff wavelength varies between 3.5 and 5.5 μm by decreasing the well width from 50 down to 25 A(ring). Dark current measurements as a function of temperature reveal activation energies for thermionic emission that closely correspond to measured cutoff wavelengths. Experimental results are in reasonable agreement with Kronig–Penney calculations. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360194
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  • 6
    Electronic Resource
    Electronic Resource
    Composition dependence of microwave properties of Y-Ba-Cu-O thin films grown by metal-organic chemical-vapor deposition (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 438-440 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films of Y-Ba-Cu-O of different composition were grown on MgO and LaAlO3 substrates by metal-organic chemical-vapor deposition. Using a microwave cavity resonator, their microwave surface resistance at 24.5 GHz was measured at a temperature of 77.5 K. It varies from less than 3 mΩ to more than 50 mΩ depending on the composition of the films. The lowest surface resistances could be obtained with samples having a composition close to the ideal stoichiometry 1:2:3 but with a slight excess of copper and yttrium. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359350
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  • 7
    Electronic Resource
    Electronic Resource
    Efficiency of photoluminescence and excess carrier confinement in InGaAsP/GaAs structures prepared by metal-organic chemical-vapor deposition (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 700-704 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Special double- and separate-confinement InGaAsP/GaAs heterostructures intended for photoluminescence measurements have been grown by low-pressure metal-organic chemical-vapor deposition. The band gap of the active region quaternary material was close to 1.5 eV, and the waveguide of the separate-confinement structures was near 1.8 eV. Measurement of the integrated luminescence efficiency at 300 K has shown that over a wide range of excitation level (10–103 W/cm2) radiative transitions are the dominant mechanism for excess carrier recombination in the active region of the structures studied. As determined by spectral measurements, the excess carrier concentration in the waveguide of the separate-confinement heterostructures and the intensity of the waveguide emission band correspond to a condition of thermal equilibrium of the excess carrier populations in the active region and the waveguide. The ratio of the intensity of the waveguide emission to the active region emission fits a model which assumes that the barrier height for minority carriers (holes) is equal to the difference in band gaps between the active region and the waveguide region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358519
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  • 8
    Electronic Resource
    Electronic Resource
    Vortex merging and spectral cascade in two-dimensional flows (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 8 (1996), S. 2263-2265 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The merging of two identical vortices is studied numerically using a spectral code. It is noted that the enstrophy cascade is most active on the distorted vortex boundaries, with a Kolmogorov-like spectrum E(k)≈k−α, α≤4, developed at high wave numbers. The inverse energy cascade is completed when the vortices merge into one of larger size. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.869027
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  • 9
    Electronic Resource
    Electronic Resource
    Heat capacity of hydrogenated diamond-like carbon films (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2340-2342 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used differential scanning calorimetry to measure the heat capacity of diamond-like carbon (DLC) film prepared by a plasma immersion ion processing method. The same calorimeter was used to measure the heat capacity of single crystal natural diamond and of high purity graphite. The amount of atomic hydrogen trapped in the DLC films was determined by elastic-recoil-detection spectrometry. The present data and literature values were used to deduce an expression for the specific heat that factors out the contribution from the sp3/sp2 bonding and from the atomic hydrogen trapped in the carbon. The data shows that the hydrogen contribution to the specific heat of carbon is independent of the sp3/sp2 bonding and amounts to about 0.63kB per hydrogen atom. We propose a simple method to determine the sp3/sp2 bonding ratio in hydrogenated DLC films based on measuring the specific heat and the hydrogen content of the sample. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1290387
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  • 10
    Electronic Resource
    Electronic Resource
    Optimized structure for InGaAsP/GaAs 808 nm high power lasers (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 3251-3253 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optimized structure for the InGaAsP/GaAs quaternary material lasers (λ=0.808 μm) is investigated for the most efficient high-power operation through an experiment and theoretical study. A comparative study is performed of threshold current density Jth and differential efficiency ηd dependence on cavity length (L) for two different laser structures with different active layer thickness (150 and 300 A(ring)) as well as for laser structures with different multiple quantum well structures. A theoretical model with a more accurate formulation for minority leakage phenomenon provides explanation for the experimental results and sets general optimization rules for other lasers with similar restrictions on the band gap and refractive index difference between the active layer and the cladding layers. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113394
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