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Isotopically modulated silicon and germanium multilayers are analyzed by means of femtosecond spectroscopy and pulsed X-ray scattering for determining thermal conductivity and phonon modes. Isotopic modulation decreases thermal conductivity stronger than expected from a band bending model in the coherent phonon transport regime, in particular for silicon. Femtosecond spectroscopy and X-ray scattering resolve zone-folded vibration modes, which are located at the edge of the new, smaller Brillouin zone due to the multilayer periodicity. These modes can contribute to the reduction of thermal conductivity by Umklapp processes within the zone-folded mini-bands. Color-coded increase in ultrafast X-ray scattering in vicinity to the mini-zone boundary of a germanium multilayer.

A new test facility is developed for the short mock-ups and the experimental validation of the cryostat is performed at cryogenic conditions. The magnetic measurement assemblage will be verified with the existing mock-up coils.

An analytical model is developed to analyze the effects of viscous flow on residual stresses in film-substrate systems. Compared to viscous flow in the film, viscous flow in the substrate results in slower stress relaxation in the system.

Porous silicon (PS) made from doped material is modeled as a uniaxial effective medium consisting of hollow cylindrical silicon shells and free cylindrical pores. Diffuse reflectance of a porous layer at its interface with air agrees with measurements of light scattering from p(super +) porous silicon at a wavelength gamma = 457 nm.

Diffuse x-ray scattering around Bragg peak (004) is investigated for p(super -)- and p(super +)-type silicon samples. The porous silicon (PS) crystallites are stressed along the q(sub z) direction and relaxed along the lateral q(sub x) direction.

The vertical variation of in-plane strain induced by an In0.1Ga0.9As single quantum well fixed in a free-standing wire structure on GaAs is analyzed using depth resolved x-ray grazing incidence diffraction. The basis of the theoretical investigation is the distorted wave Born approximation for grazing incidence geometry. By fitting the complete set of experimental grating truncation rods simultaneously, the structural parameters of the surface nanostructure were identified. The results are discussed.

Porous silicon (PS) has potential applications in 'all silicon optoelectronics'. A structural investigation of thin PS layers and multilayers has been undertaken, using high resolution x-ray diffraction. Information can be deduced about porous layer parameters including porosity, lattice parameter, interface transition and thickness, in a nondestructive way. Several thickness fringes, and some satellites were observed.

In this article, we combine diffuse x-ray scattering with a Monte Carlo simulation method for the determination of the dislocation density in thin heteroepitaxial layers. As a model, we consider GaN epitaxial layers containing threading dislocations perpendicular to the surface. The densities of particular types of threading dislocations following from the comparison of measured and simulated distributions of diffusely scattered x-ray intensity are compared with the dislocation densities determined by etching. A good agreement was found. [ABSTRACT FROM AUTHOR]

Presents information on a study of how the strain relaxation of the multilayer grating evolves toward the free surface and how the local strain distribution is modulated due to the compositional profile of the layered setup. Experimental details; Fit of the experimental results; Conclusions.

In this work a double-crystal setup is employed to study compound refractive lenses made of single-crystal diamond. The point spread function of the lens is calculated taking into account the lens transmission, the wavefront aberrations, and the ultra-small-angle broadening of the X-ray beam. It is shown that, similarly to the wavefront aberrations, the ultra-small-angle scattering effects can significantly reduce the intensity gain and increase the focal spot size. The suggested approach can be particularly useful for the characterization of refractive X-ray lenses composed of many tens of unit lenses. [ABSTRACT FROM AUTHOR]

We report results of the computed tomography reconstruction of the index of refraction in a whole rabbit knee joint examined at the photon energy of 51 keV. Refraction based images make it possible to delineate the bone, cartilage, and soft tissues without adjusting the contrast window width and level. Density variations, which are related to tissue composition and are not visible in absorption X-ray images, are detected in the obtained refraction based images. We discuss why refraction-based images provide better detectability of low contrast features than absorption images. [ABSTRACT FROM AUTHOR]

A procedure for obtaining three-dimensionally resolved reciprocal-space maps in a skew X-ray diffraction geometry is described. The geometry allows tuning of the information depth in the range from tens of micrometres for symmetric skew diffraction down to tens of nanometres for strongly asymmetric skew geometries, where the angle of incidence is below the critical angle of total external reflection. The diffraction data are processed using a rotation matrix formalism. The whole three-dimensional reciprocal-space map can be measured by performing a single azimuthal rotation of the sample and using a two-dimensional detector, while keeping the angle of incidence and the X-ray information depth fixed (FIXD method). Having a high surface sensitivity under grazing-incidence conditions, the FIXD method can be applied to a large variety of Bragg reflections, particularly polar ones, which provide information on strain and chemical composition separately. In contrast with conventional grazing-incidence diffraction, the FIXD approach reveals, in addition to the lateral (in-plane) components, the vertical (out-of-plane) component of the strain field, and therefore allows the separation of the scattering contributions of strained epitaxial nanostructures by their vertical misfit. The potential of FIXD is demonstrated by resolving the diffraction signal from a single layer of InGaN quantum dots grown on a GaN buffer layer. The FIXD approach is suited to the study of free-standing and covered near-surface nano-objects, as well as vertically extended multilayer structures. [ABSTRACT FROM AUTHOR]

Quantitative characterization of local strain in silicon wafers is critical in view of issues such as wafer handling during manufacturing and strain engineering. In this work, full-field X-ray microdiffraction imaging using synchrotron radiation is employed to investigate the long-range distribution of strain fields in silicon wafers induced by indents under different conditions in order to simulate wafer fabrication damage. The technique provides a detailed quantitative mapping of strain and defect characterization at the micrometer spatial resolution and holds some advantages over conventional methods. [ABSTRACT FROM AUTHOR]