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  • 1
    Electronic Resource
    Electronic Resource
    An MBE growth facility for real-time in situ synchrotron x-ray topography studies of strained-layer III–V epitaxial materials : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 634-637 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes a unique combined UHV MBE growth x-ray topography facility designed to allow the first real-time synchrotron radiation x-ray topography study of strained-layer III–V growth processes. This system will enable unambiguous determination of dislocation nucleation and multiplication processes as a function of controlled variations in growth conditions, and also during post-growth thermal processing. The planned experiments have placed very stringent demands upon the engineering design of the system, and design details regarding the growth chamber; sample manipulator, x-ray optics, and real-time imaging systems are described. Results obtained during a feasibility study are also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142675
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of nanometer-scale epitaxial structures by grazing-incidence x-ray diffraction and specular reflectivity (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 1936-1941 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: X-ray rocking curve analysis is a powerful and nondestructive technique for the characterization of heteroepitaxial structures. Conventionally, measurements are performed in symmetrical scattering geometry using a double-crystal x-ray diffractometer but the technique can be extended to the study of very thin layers (〈200 A(ring)) by the use of glancing-incidence scattering geometry and a triple-crystal diffractometer. These structures can also be studied by the technique of total external x-ray reflectivity. This is sensitive to the electron-density profile of the heterostructure as a function of depth. By combining the above techniques we have found it possible to obtain structural information on layers as thin as 20 A(ring). Such measurements permit accurate measurement of individual layer thicknesses and interface roughnesses on the angstrom level. The lattice parameter strain can be obtained by modeling of the intensity distribution of the crystal truncation rod.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339895
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of the thickness of Al2O3 barriers in magnetic tunnel junctions (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 81 (2002), S. 751-753 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The barrier thickness in magnetic spin-dependent tunnel junctions with Al2O3 barriers has been measured using grazing incidence x-ray reflectivity and by fitting the tunneling current to the Simmons model. We have studied the effect of glow discharge oxidation time on the barrier structure, revealing a substantial increase in Al2O3 thickness with oxidation. The greater thickness of barrier measured using grazing incidence x-ray reflectivity compared with that obtained by fitting current density–voltage to the Simmons electron tunneling model suggests that electron tunneling is localized to specific regions across the barrier, where the thickness is reduced by fluctuations due to nonconformal roughness. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1496131
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  • 4
    Electronic Resource
    Electronic Resource
    Weak magnetic moment on IrMn exchange bias pinning layers (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 985-987 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present evidence from soft x-ray resonant magnetic scattering measurements at the Mn L3 edge for the existence of a small magnetic moment on the antiferromagnetic IrMn pinning layer in a NiFe/Cu/Co/IrMn spin valve structure. The variation of the signal in an applied magnetic field shows that the moment lies antiparallel to the Co moment. Changes in the Mn L3 edge signal as the Co moment is rotated into the hard direction are rapid and do not appear to be associated with thermal reordering of the antiferromagnetic domain structure. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1392304
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  • 5
    Electronic Resource
    Electronic Resource
    Dependence of the critical thickness on Si doping of InGaAs on GaAs (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2156-2158 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The formation of misfit dislocations during the initial stages of relaxation of In0.04Ga0.96As epitaxial layers on (001) GaAs has been studied by in situ high-resolution double crystal x-ray topography during molecular beam epitaxy growth. Relaxation is initially anisotropic with the fast B(g) dislocations being nucleated before the slow A(g) set. On doping with Si up to a maximum concentration of 4×1018 atoms/cm3, an increase in critical thickness was observed for both dislocation sets. The data can be fitted to an extension of the Matthews–Blakeslee model that includes a lattice friction force varying linearly with the dopant concentration. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1315342
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  • 6
    Electronic Resource
    Electronic Resource
    X-ray topography of the coherency breakdown in GexSi1−x/Si(100) (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 2083-2085 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An x-ray topography study is presented of the coherency breakdown in GexSi1−x/Si(100) strained epilayers. Finite dislocation densities (in excess of 103 cm−2) are observed at compositions in the range 12–13 at. % Ge for an epilayer thickness of h≈180 nm. Above 13 at. % Ge the dislocation density starts to change rapidly and this composition is identified as critical for h≈180 nm, a thickness which is almost a factor of 4 lower than the accepted "critical'' thickness for this lattice mismatch. The result suggests that in low-mismatched GexSi1−x alloys the dislocation density will increase continuously at the "critical'' thickness, as opposed to exhibiting a sharp onset. The implications of these results to the various models of the critical thickness transition are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100288
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  • 7
    Electronic Resource
    Electronic Resource
    High resolution x-ray diffraction and scattering measurement of the interfacial structure of ZnTe/GaSb epilayers (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 2281-2287 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The surface and interface structures of ZnTe epilayers grown by molecular beam epitaxy on GaSb (001) substrates under different conditions have been investigated by high resolution x-ray diffraction and grazing incidence scattering. Reciprocal space mapping around the symmetrical diffraction reciprocal point 004 and asymmetrical diffraction point 1¯1¯5 showed that the ZnTe epilayers, in the samples investigated, were fully strained to the substrate. The crystalline quality of the ZnTe epilayer grown on a substrate annealed in a Zn flux was very good, while evidence for an interfacial layer, of thickness varying from 2–20 nm, was found when the substrate was annealed in a Te flux prior to growth. This is attributed to Ga2Te3 formation at the interface. The interfacial layer roughens the interface and surface, and both crystal truncation rod measurements and grazing incidence x-ray reflectivity show the surface roughness to be about 4 nm. Such a rough surface and interface is also inferred from the broader distribution along the transverse direction in reciprocal space maps. A shorter lateral correlation length is found for the roughness of the sample containing the interfacial layer. The disappearance of interference fringes is attributed to nonuniformity of the interfacial layer. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366035
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  • 8
    Electronic Resource
    Electronic Resource
    Epitaxial growth of (Hg,Mn)Te by the interdiffused multilayer process (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 2983-2985 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial films of (Hg,Mn)Te have been grown by metalorganic vapor phase epitaxy using the interdiffused multilayer process (IMP), on GaAs (100) substrates with a ∼1 μm buffer layer of CdTe. In order to grow the MnTe component, it was found necessary to grow at 380 °C with a precursor partial pressure ratio (Mn:Te) of 5–8. The IMP layers were found to be more uniform in composition and thickness than comparable layers of (Hg,Mn)Te grown by the more conventional direct alloy growth method. X-ray rocking curve widths for IMP layers were typically ∼200‘ with a variation across the layer of ∼10%. Variations in composition were 〈10%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109164
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  • 9
    Electronic Resource
    Electronic Resource
    Measurement of aluminum concentration in epitaxial layers of AlxGa1−xAs on GaAs by double axis x-ray diffractometry (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2272-2274 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The composition of a series of AlxGa1−xAs layers grown epitaxially by molecular beam epitaxy (MBE) on GaAs has been measured independently by double axis x-ray diffractometry and reflection high-energy electron diffraction. From a quadratic fit to the data, we deduce the lattice parameter mismatch between AlAs and GaAs and the Poisson ratio of AlAs. Asymmetric reflection rocking curves and synchrotron x-ray topography have been used to show that the anomalously low substrate-layer peak splitting for the 1-μm-thick AlAs layer results from relaxation, which is asymmetric. Use of the AlAs rocking curve peak splitting corrected for relaxation yields a mismatch of 1600 ppm (±1%) between AlAs and GaAs, and 0.28±0.01 for the Poisson ratio of AlAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106041
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  • 10
    Electronic Resource
    Electronic Resource
    Direct imaging of travelling Rayleigh waves by stroboscopic X-ray topography (1982)
    [s.l.] : Nature Publishing Group
    Nature 299 (1982), S. 44-46 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Piezoelectric SAW devices1 are of great technological importance for high-frequency signal processing and filtering applications. Although the presence of crystallographic defects can have deleterious effects on the characteristics of these devices, there has been almost no study of the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/299044a0
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