Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1985-1989  (6)
Source
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Anisotropy of thermal expansion of GaAs on Si(001) (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 2117-2119 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the thermal expansion between 20 and 450 °C of epitaxially grown GaAs thin films on Si(001) as well as of the Si substrate by means of high-resolution x-ray scattering. Our results show that the thermal expansion of GaAs in the direction parallel to the film plane follows the thermal expansion of the silicon substrate and is therefore smaller than in bulk GaAs. Furthermore, the thermal expansion perpendicular to the film plane (parallel to the growth direction) exceeds the bulk GaAs value by the Poisson contribution as a result of the in-plane constraint. The thermal expansion coefficients for GaAs films on Si(001) substrates in the directions parallel and perpendicular to the film plane are αT(parallel)(GaAs) =3.46×10−6/K and αT⊥(GaAs) =8.91×10−6/K, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99553
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Terracing in strained-layer superlattices (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3024-3030 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on an x-ray diffraction study of GaAs/GaAs1−xSbx superlattices grown by molecular-beam epitaxy on miscut GaAs (100) substrates. The fundamental reflections of the superlattice lie on a reciprocal lattice rod which is tilted with respect to the reciprocal lattice rod of the substrate. The satellite reflection, in turn, lies on lines making a constant angle with the reciprocal lattice rod containing the fundamental reflections. This result is attributed to a terraced superlattice which, in addition, is tilted with respect to the substrate. We describe a model which approximates the misfit strain imposed on the superlattice at the interfacial step, and which is capable of relating the average tilt angle to the misfit strain. The same model can also explain the transverse broadenings observed for the superlattice peaks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342494
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Neutron scattering investigation of a quasi-two-dimensional planar ferromagnet (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 3554-3556 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetic ordering of stage-2 CoCl2-graphite intercalation compound has been investigated by neutron diffraction. This compound is a layered structure, with ferromagnetic coupling between xy-type spins within the same layer and a much weaker antiferromagnetic coupling between successive layers. The interplanar coupling is sufficiently weak that the ordering occurs in two steps, leaving a temperature window between Tl≈8.8 K and Tu≈9.4 K where the ordering is purely two dimensional. Below Tl the spins become weakly correlated along the c axis, but this correlation never grows beyond two magnetic layers. We have measured the static spin correlation function by neutron scattering. At all relevant temperatures the scattering is markedly two dimensional and consists of two parts: a short-range order term with maximum correlation length and intensity at Tu, and a sharp Bragg-like ridge of constant width, which vanishes above Tu and relates to either long-range order or a power-law decay of the order parameter. Results will be analyzed in light of current theories, in particular, of the vortex binding mechanism proposed by Kosterlitz and Thouless.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.340741
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Structural properties of GaAs on (001) oriented Si and Ge substrates (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 1023-1029 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detailed x-ray scattering study of GaAs grown by molecular beam epitaxy on (001) oriented Si and Ge substrates is reported. It is shown that the broadening of the GaAs Bragg peaks can be understood in terms of residual strains for samples 2 μm thick. For a sample 0.2 μm thick, domain size broadening effects corresponding to the total thickness of the GaAs film must also be included in order to explain the peak widths. In none of the samples was any evidence of antiphase domain broadening observed and we are thus able to place a minimum of 4000 A(ring) on the size of any possible antiphase domains. We also find that the GaAs lattice is incommensurate with the Si substrate and that the GaAs is tetragonally distorted at room temperature. This distortion is explained by the difference in the thermal expansion of GaAs and Si.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338192
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Material properties of high-quality GaAs epitaxial layers grown on Si substrates (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 1640-1647 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report an investigation of the materials properties of GaAs on Si epitaxial layers. By using properly oriented substrates, we have found that a substantial reduction in the density of threading dislocations can be achieved. In the presence of steps, dislocations with their Burgers vectors in the (100) substrate plane are preferentially generated, which are more effective in accommodating lattice mismatch and do not thread into the epitaxial layer. We have also found that the density of threading dislocations can be reduced significantly by the use of GaAs/InGaAs pseudomorphic superlattices. Using these techniques, dislocation densities of as low as 103–104 cm−2 have been achieved in 2-μm-thick GaAs on Si epitaxial layers. In growth on nominal (100) orientations, where it is known that single atomic steps dominate, we have found no evidence of antiphase domains by transmission electron microscopy or chemical etching. This result suggests that it may not be energetically favorable for antiphase domains to form in these samples. Alternatively antiphase domains may propagate along the {111} directions and annihilate one another. For GaAs/(Al,Ga)As double heterojunction (DH) laser structures on Si substrates, the dislocation control techniques have made possible electroluminescence intensity (spontaneous emission) within a factor of 2 of state-of-the-art DH lasers on GaAs (which for reference lased at a current threshold density of 600 A/cm2). These results compare to within experimental determination. Electroluminescence intensities were also found to increase with increasing initial growth temperature. Stripe geometry lasers with room-temperature pulsed threshold currents as low as 170 mA for 10×240 μm2 stripe have been obtained using these techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337253
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Hydrogen in Nb/Ta superlattices (1989)
    Springer
    The European physical journal 74 (1989), S. 457-473 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The structural and thermodynamic properties of hydrogen dissolved in Nb/Ta superlattices are studied by in-situ x-ray scattering techniques. From the x-ray satellite intensities, it is found that H induces a strain modulation exhibiting a Curie-Weiss temperature dependence. The intensities are analyzed in terms of a mean field model of the modulated lattice gas, yielding quantitative information on the hydrogen-metal and hydrogen-hydrogen interaction energies. Critical behavior associated with a gas-liquid transition is also observed. Hydrogen density fluctuations with wavelengths shorter than a superlattice period are, however, suppressed by the superlattice, which represents a novel manifestation of a coherent phase transition. These experiments provide new and fundamental insight into the role of spacially varying two body interactions in critical phenomena.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01311393
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...