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  • 1
    Electronic Resource
    Electronic Resource
    A study of Franz–Keldysh oscillations of GaAs/Si/GaAs and AlAs/Si/AlAs heterostructures (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 3616-3619 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have carried out a detailed study of Franz–Keldysh oscillations observed in the photoreflectance spectra of molecular beam epitaxy grown GaAs/Si/GaAs and AlAs/Si/AlAs heterostructures with a Si nominal thickness of two monolayers. The oscillations in the photoreflectance spectra were due to internal electric fields generated by graded p-n junctions created by Si diffusion. The data were analyzed employing the asymptotic Franz–Keldysh theory. It is concluded that different contributions from degenerate heavy and light hole bands, to transitions around the Γ point of the Brillouin zone, must be expected for different heterostructures depending upon the particular characteristics of the internal electric fields present in the sample.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357422
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  • 2
    Electronic Resource
    Electronic Resource
    Ferroelectric behavior of epitaxial Bi2VO5.5 thin films on Si(100) formed by pulsed-laser deposition (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 1193-1195 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films of Bi2VO5.5 have been prepared epitaxially using a pulsed-laser deposition method on a Si(100) substrate using TiN as a buffer layer and SrTiO3 as a seed layer. The films have smooth surface morphology with atomically flat terraces and steps of 4 Å in height. The ferroelectric characterization shows a spontaneous polarization of 2.2 μC/cm2 and a coercive field (Ec) of 22 kV/cm. The leakage current obtained is about 5×10−6 A/cm2 at a drive voltage of ±2 V. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373798
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  • 3
    Electronic Resource
    Electronic Resource
    Low leakage current characteristics of YMnO3 on Si(111) using an ultrathin buffer layer of silicon oxynitride (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 6598-6604 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have grown YMnO3 (YMO) thin films on Si(111) using silicon oxynitride (SiON) as a buffer layer. Thickness of SiON buffer layer was well controlled within 2 nm. High resistance of ultrathin SiON layer (dSiON∼0.7 nm) to Si oxidation was confirmed by x-ray photoelectron spectroscopy (XPS). Using the ultrathin SiON layer, we obtained c-axis oriented ferroelectric phase of YMO. Although capacitance–voltage curves of Al/YMO/SiON/Si(111) showed hystereses attributed to ferroelectricity of the YMO films, the memory window was not sufficient (0.2 V), seemingly due to poor crystallinity of the YMO films. On the other hand, leakage current characteristic was good enough for application. The typical value of leakage current density was 10−8 A/cm2 at a drive voltage of ±5 V. In this article, the details of the characterization elucidated by using x-ray diffraction, atomic force microscopy, and XPS will be shown as well. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1315614
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  • 4
    Electronic Resource
    Electronic Resource
    Segregation and interdiffusion of In atoms in GaAs/InAs/GaAs heterostructures (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1770-1775 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The segregation and interdiffusion of In atoms in the GaAs/InAs/GaAs heterostructures were investigated by secondary-ion mass spectroscopy. When the 1-ML-thick InAs layer was grown in a layer-by-layer growth mode with no dislocations, the segregation of In atoms became marked with the increase of the growth temperature. However, the segregation was observed even at a relatively low growth temperature of 400 °C in molecular beam epitaxy. It was found that the segregation was markedly enhanced by dislocations near the heterointerface when thick InAs layers were grown in a three-dimensional island growth mode. The interdiffusion of In atoms toward the growth direction occurred after thermal annealing, which could be assisted by vacancies propagating from the film surface into the epilayer. It became apparent that the interdiffusion was effectively suppressed by a thin AlAs layer inserted in the GaAs cap layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354806
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  • 5
    Electronic Resource
    Electronic Resource
    An analysis of the Pr contribution to the spin-reorientation phenomenon in PrCo5 : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6131-6133 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spin-reorientation phenomenon in the PrCo5 compound has been analyzed over the temperature range 0 to 300 K using a Hamiltonian consisting of the crystal-field term and the 4f–3d exchange interaction. We have performed a careful analysis by including the second- and the fourth-order interaction terms to the crystal-field Hamiltonian. In general, the crystal-field B02 term favors the planar anisotropy while B04 term promotes an axial anisotropy. The combination of these two terms yield the off-axial anisotropy of the Pr sublattice. The magnitudes of B02 and B04 contribution are relatively strong at low temperatures and decrease considerably with increasing temperature. The contribution of the B02 term is more pronounced than that of the B04 term throughout the temperature range investigated. The competition between the off-axial anisotropy of Pr sublattice and the axial anisotropy of Co sublattice yields the spin-reorientation transition phenomenon in PrCo5 at 105 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350019
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of crystal alignment on the remanence of sintered NdFeB magnets (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4610-4612 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nd15.4Fe77.8B6.8 magnets of various degrees of crystal alignment have been prepared by the conventional powder metallurgy technique. The alignment of these magnets have been determined by x-ray diffraction and fitting the standard deviation of a Gaussian distribution for the relative intensity versus the angle between the normals of (hkl) and the tetragonal c axis. The standard deviation is a good indicator for crystal alignment. An aligning field of 8 kOe is found to be essential to obtain a well-aligned NdFeB magnet. The remanence of sintered magnets is directly affected by the crystal alignment. Furthermore, the effect of crystal alignment on the remanence follows the theoretical prediction of the Stoner–Wohlfarth model. Below the spin reorientation temperature, the effect of crystal alignment on the shape of hysteresis loop becomes more significant. The remanences extrapolated from first and second quadrant of the hysteresis loops have been found to be consistent with the prediction of Stoner–Wohlfarth model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344828
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  • 7
    Electronic Resource
    Electronic Resource
    Growth mechanism of (InAs)m(GaAs)n strained short-period superlattices grown by molecular beam epitaxy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 7257-7263 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The growth mechanism of (InAs)m(GaAs)n strained short-period superlattices grown on GaAs(001) and InAs(001) substrates was investigated by reflection high-energy electron diffraction and transmission electron microscopy. In the growth on a GaAs substrate, the two-dimensional layer-by-layer growth mode (Frank–Van der Merwe mode) was successfully realized even over the critical thickness when the lattice mismatch is less than ∼2.4%. In this case, the critical thickness of the grown layer on GaAs was remarkably increased by applying the superlattice structures. However, the strained short-period superlattices on InAs substrate were grown in the Stranski–Krastanov mode. The growth mode of strained short-period superlattices can be explained by the balance of surface and interface free energies, which could relate to the difference of the bonding energy between In-As and Ga-As. The growth mode of strained short-period superlattices depended strongly on the growth temperature. In the relatively high temperature growth, the growth mode of strained short-period superlattice grown on a GaAs substrate was changed from the Frank–Van der Merwe mode to the Stranski–Krastanov mode. It could be attributed to intermixing of superlattice structure due to the surface segregation of In atoms assisted by thermal energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355016
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  • 8
    Electronic Resource
    Electronic Resource
    A study on the c-axis alignment of Nd-Fe-B die-upset magnets (abstract) : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6636-6636 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is necessary to get higher c-axis alignment of Nd2Fe14B grains in Nd-Fe-B magnets for higher-energy products. During the hot working process, where melt-spun flakes were hot pressed followed by die-upsetting, hot-pressed bodies showed roughly isotropic structure while c-axis alignments were developed during die-upsetting. In this report, we studied the relationship between the reductions during upsetting and the degree of the c-axis alignments and also tried to get the formula of this relationship. We prepared samples having different reductions and evaluated remanence, c-axis alignment and strains of each flake in the samples. c-axis alignments were evaluated using x-ray diffraction.1 Strains were measured using the sizes of each deformed melt-spun flake. In the range of 50%–70% reduction, remanence was lower in the surface layer than in the center. The difference in remanence in these two regions became smaller as the reduction became larger. The distribution of c-axis alignments and strains showed similar phenomena. Then we could propose the following formula showing the relationship between reduction and c-axis alignment: (σ − σ0)/(σi − σ0) = (1 − εz)4, where σ is standard deviation of c axis alignment and σ0, σi denotes the σ value at enough large strain and initial value of σ, respectively. εz means strain parallel to pressing axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349832
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  • 9
    Electronic Resource
    Electronic Resource
    Operational characteristics of the impregnated-electrode-type liquid-metal ion source with multiple tip and reservoirs : Proceedings of 5th international conference on ion sources (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1351-1353 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new type of impregnated-electrode-type liquid-metal ion source, which eliminated the heating problem in the previous source, has been developed with multiple tip and reservoirs (TAR's). In the present ion source, the TAR's are connected electrically in series by modifying the TAR holding system. In order to achieve uniform heating of the TAR's, the materials of the knife-edged electrodes, which introduce the heating current to the TAR's, were examined. Tantalum electrodes exhibited better results as compared with the conventional Mo electrodes. Both of the two TAR's could be heated up to 700 °C with a heating power of 200 W. The maximum indium ion current of 9.1 mA was obtained from the four-TAR source with 40 emission points. Since the present ion current was limited by the current capacity of the extraction power supply, an ion current of more than 10 mA will be expected with a larger power supply. The results indicated that an ion current approximately proportional to the number of the emission points was obtained. This kind of ion source could be used as a general ion source in materials science.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144956
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  • 10
    Electronic Resource
    Electronic Resource
    Solid phase epitaxial growth of GaAs on Si (111) (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1664-1666 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A continuous GaAs film was successfully grown on Si(111) at the initial stage (20 A(ring) growth thickness) by solid phase epitaxial growth. This growth suppressed the island formation observed with direct growth of GaAs on Si. The GaAs(111)A was obtained for the first time on Si(111) with an As prelayer deposited at 20 °C and 350 °C. The GaAs(111)B was also grown on Si(111) with an As prelayer deposited at 580 °C and 700 °C. The polarity of the (111) GaAs epitaxial film depends on the substrate temperature at which the As prelayer is deposited on Si.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103110
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