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  • 1
    Electronic Resource
    Electronic Resource
    Magneto-optical studies of GaN and GaN/AlxGa1−xN: Donor Zeeman spectroscopy and two dimensional electron gas cyclotron resonance (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 8007-8010 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magneto-optical experiments have been performed on free and bound electrons in GaN films and GaN/AlGaN heterojunctions. Cyclotron resonance of two dimensional electron gas in GaN/ AlxGa1−xN heterojunctions has yielded m* = 0.23 m0, x-dependent scattering times consistent with values from transport measurements, and an apparent unexplained level crossing at 70 cm−1. Infrared absorption of doped GaN films has shown that the binding energy of Si donors, 29.0 meV, is much smaller than that of residual donors, in agreement with transport measurements, thus suggesting donor spectroscopy as a useful technique for defect/impurity qualitative analysis. Zeeman effect of the donor spectra has been used to determine the GaN low frequency dielectric constant, ε0 = 10.4. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362351
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  • 2
    Electronic Resource
    Electronic Resource
    Oscillatory cyclotron resonance effective mass near ν=1 and 2 in modulation-doped ZnSe/Zn1−x−yCdxMnySe (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6466-6468 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The fabrication by molecular-beam epitaxy of modulation-doped magnetic semiconductor heterostructures results in the creation of novel "magnetic" two-dimensional electron gases (2DEGs) with unusual transport properties. We report on the measurements of cyclotron resonance (CR) and effective mass in magnetic 2DEGs formed in modulation-doped ZnSe/Zn1−x−yCdxMnySe single quantum wells. Far-infrared absorption measurements are carried out at a nominal temperature of 4.2 K and in fields up to 30 T on these magnetic samples, as well as on corresponding nonmagnetic samples (ZnSe/Zn1−xCdxSe single quantum wells). The samples have carrier densities ranging from 1 to 4×1011 cm−2 and mobilities as high as 42 000 cm2/V s for the nonmagnetic samples. For the magnetic samples, the magnetic field dependence of the CR frequency shows marked oscillatory deviations from linearity in the vicinity of integer filling factors ν=2 and ν=1. For instance, compared to the nonmagnetic samples, the amplitude of the oscillations in the effective mass of the magnetic samples changes by 15% at half-filling factor. This is significantly larger than similar oscillatory effective mass behavior observed in standard semiconductor 2DEGS (e.g., GaAs/GaAlAs), suggesting a qualitatively different physical origin for this phenomenon in these magnetic systems. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372740
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  • 3
    Electronic Resource
    Electronic Resource
    Metal-to-insulator transition in sputter deposited 3Ni/Al thin films (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 2609-2616 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films with a 3Ni/1Al atomic ratio were synthesized using low-power dc planar magnetron sputtering from a nickel–aluminum alloy target. Chemical analysis revealed that a significant amount of oxygen was incorporated into the Ni–Al thin films which were prepared under a typical vacuum of ∼1×10−5 mbar. These thin films were found to exhibit a prominent temperature dependence of electrical resistance, the magnitude of which diminishes upon increasing the film thickness or the in situ deposition temperature. Cross-sectional transmission electron microscopy revealed a nanocrystalline structure of the films which changes as a function of deposition temperature. Electron diffraction indicates the existence of a single-phase face-centered cubic structure in the nanocrystallites, yet with an enormous expansion of the crystal lattice for the low temperature deposited films when compared with the intermetallic Ni3Al lattice. On raising the deposition temperature or increasing the film thickness, however, the lattice constant gradually declines toward the lattice constant of bulk Ni3Al. An attempt is made to correlate the lattice structures of the crystallites and the electrical properties of the films with the potential influence of the dissolved oxygen in the Ni–Al lattice. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1286773
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  • 4
    Electronic Resource
    Electronic Resource
    Increase conductivity in UNiSn with the application of magnetic fields : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4928-4930 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the frequency dependent conductivity of the modified Huesler alloy UNiSn in the antiferromagnetic state and in the presence of a magnetic field. UNiSn is paramagnetic above 43 K and has a semiconducting gap of about 65 meV. Below 43 K, the compound is in an itinerant antiferromagnetic state. The reflectance of UNiSn is measured from 4 meV to 0.4 eV and in fields up to 16 Tesla. At 5 K, there is a shift in spectral weight from the gap region to lower frequencies as the applied magnetic field is increased. This shift in spectral weight gives rise to increase conductivity with applied field in the metallic state. However, the gap value is unaffected by the field. No field dependence is observed for the isostructural compound, ThNiSn, which does not undergo an antiferromagnetic transition. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364999
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  • 5
    Electronic Resource
    Electronic Resource
    Cyclotron resonance in modulation-doped ZnSe/Zn1−xCdxSe and ZnTe/CdSe single quantum wells (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 3662-3664 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report low-temperature (4.2 K) cyclotron resonance measurements on high-mobility, two-dimensional electron gases in modulation-doped ZnSe/Zn1−xCdxSe (x=0.06, 0.12, and 0.24) single quantum wells, as well as in a modulation-doped ZnTe/CdSe single quantum well. These experiments carried out in magnetic fields ranging up to 17 T yield reliable measurements of the effective mass m* of conduction-band electrons in Zn1−xCdxSe alloys, including the measurement of m* in cubic CdSe. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125421
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  • 6
    Electronic Resource
    Electronic Resource
    Superconducting free-standing thin films of YBa2Cu3Ox (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 201-202 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a new technique of preparing unsupported thin films of YBa2Cu3Ox. These films are about 6×6 mm2 and less than half a micron thick. They were prepared via laser ablation on thin carbon films typically of order 50 μg/cm2 (∼2500 A(ring)). When the film was annealed, the carbon oxidized leaving behind a free-standing film. The film has a superconducting orthorhombic phase and an onset temperature of (approximately-equal-to)85 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103935
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  • 7
    Electronic Resource
    Electronic Resource
    Preparation and structure of a ternary oxide of barium and rhenium, Ba3Re2-xO9 (1978)
    s.l. : American Chemical Society
    Inorganic chemistry 17 (1978), S. 699-701 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic50181a039
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  • 8
    Electronic Resource
    Electronic Resource
    High reflectivity and broad bandwidth AlN/GaN distributed Bragg reflectors grown by molecular-beam epitaxy (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2818-2820 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A number of distributed Bragg reflectors (DBRs) based on AlN/GaN quarterwave layers have been grown on (0001) sapphire by electron cyclotron resonance plasma-assisted molecular-beam epitaxy. The number of periods for the DBRs ranges from 20.5 to 25.5 and the thickness of the quarterwave layers were chosen such that the peak reflectance occurs from the near ultraviolet to green wavelength regions. Peak reflectance values between 97% and 99% were obtained for these DBRs. The best sample has a peak reflectance up to 99% centered at 467 nm with a bandwidth of 45 nm. The experimental reflectance data for this sample were compared with simulations using the transmission matrix method and show excellent agreement with respect to peak reflectance, bandwidth of high reflectance, and the locations of the sidelobes. The thickness of the quarterwave layers and uniform periodicity of the bilayers were confirmed by cross-section transmission electron microscopy. A network of cracks was observed in some of the samples and this is attributed to tensile stress in the AlN layers. We have grown asymmetric DBRs with thicker AlN layers and thinner GaN layers to reduce the tensile strength in the AlN layers. Such an approach resulted in samples that have significantly less cracks or even crack-free. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126483
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  • 9
    Electronic Resource
    Electronic Resource
    Spontaneous formation of complex and ordered structures on oxygen-plasma-treated elastomeric polydimethylsiloxane (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 721-723 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this letter, we describe the spontaneous formation of complex and ordered structures on polydimethylsiloxane when subjected to oxygen plasma treatment. Periodicity of wavy structures from submicrometer to micrometer length scales could be generated reproducibly and quantitatively accounted for. The origin of these patterns could be related to the relief of compressive stress by buckling of the silica-like thin film that was formed as a result of the plasma exposures. Atomic force microscope has been used to characterize the varied trends of the modifications. The present approach could be extended to the fabrication of intricate ordered patterns on polymeric surfaces with integrated relief structures obtained by soft lithography and micromolding. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125873
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  • 10
    Electronic Resource
    Electronic Resource
    Erratum: "Distributed Bragg reflectors based on AlN/GaN multilayers" [Appl. Phys. Lett. 74, 1036 (1999)] (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 4070-4070 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123264
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