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562 results on '"Baruchel, J"'

17. Epitaxial GaAs for X-ray imaging

Author

Sun, G.C., Rao, R., Makham, S., Bourgoin, J.C., Zhang, X.Y., Gohier, R., Masiello, F., Härtwig, J., Baruchel, J., Ponchut, C., Balocchi, A., Marie, X., Gilard, O., Roch-Jeune, I., and Pesant, J.C.

Published
2011
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32. Synchrotron Bragg diffraction imaging characterization of synthetic diamond crystals for optical and electronic power device applications1 1

Author

Tran Thi, Thu Nhi, Morse, J., Caliste, D., Fernandez, B., Eon, D., Härtwig, J., Barbay, C., Mer-Calfati, C., Tranchant, N., Arnault, J. C., Lafford, T. A., and Baruchel, J.

Subjects
topography, diamond, rocking curve imaging, X-ray diffaction, Research Papers
Abstract

Bragg diffraction imaging techniques are described, and their capabilities for studying the quality of diamond substrates and overgrown layers, and the surface damage caused by mechanical polishing, are illustrated by examples., Bragg diffraction imaging enables the quality of synthetic single-crystal diamond substrates and their overgrown, mostly doped, diamond layers to be characterized. This is very important for improving diamond-based devices produced for X-ray optics and power electronics applications. The usual first step for this characterization is white-beam X-ray diffraction topography, which is a simple and fast method to identify the extended defects (dislocations, growth sectors, boundaries, stacking faults, overall curvature etc.) within the crystal. This allows easy and quick comparison of the crystal quality of diamond plates available from various commercial suppliers. When needed, rocking curve imaging (RCI) is also employed, which is the quantitative counterpart of monochromatic Bragg diffraction imaging. RCI enables the local determination of both the effective misorientation, which results from lattice parameter variation and the local lattice tilt, and the local Bragg position. Maps derived from these parameters are used to measure the magnitude of the distortions associated with polishing damage and the depth of this damage within the volume of the crystal. For overgrown layers, these maps also reveal the distortion induced by the incorporation of impurities such as boron, or the lattice parameter variations associated with the presence of growth-incorporated nitrogen. These techniques are described, and their capabilities for studying the quality of diamond substrates and overgrown layers, and the surface damage caused by mechanical polishing, are illustrated by examples.

Published
2017

39. Inception and movement of a ‘subgrain boundary precursor’ in ice under an applied stress, observed by X-ray synchrotron radiation Bragg imaging1

Author

Philip, A., Capolo, L., Meyssonnier, J., and Baruchel, J.

Subjects
single-crystal Bragg diffraction, deformation mechanism, Astrophysics::High Energy Astrophysical Phenomena, ice, Physics::Accelerator Physics, Physics::Optics, Research Papers, Physics::Atmospheric and Oceanic Physics, Physics::Geophysics, dislocations
Abstract

Both optical microscopy with polarized light and polychromatic beam synchrotron X-ray diffraction imaging (white-beam topography) are used to study in situ the way an ice single-crystal deforms., Basal slip of dislocations, the easiest deformation mechanism of ice crystals, does not allow a response to any strain state. The first steps of another mechanism, with a moving subgrain boundary precursor region, which permits accommodating the effect of an applied load, is investigated on an ice single crystal, mainly using synchrotron radiation Bragg diffraction imaging. During this process, the evolution of the local integrated intensity shows that there is both a general multiplication of dislocations within the crystal and a movement of basal dislocations towards the surface. The ‘subgrain boundary precursor’ region evolves towards a classical grain boundary when further deformed.

Published
2015

44. Structural defects in Hg1-xCdxI2 layers grown on CdTe substrates by vapor phase epitaxy

Author

Sochinskii, N.V., Munoz, V., Espeso, J.I., Baruchel, J., Marin, C., and Dieguez, E.

Subjects
Crystals -- Structure, Microstructure -- Research, Dislocations in crystals -- Research, Physics
Abstract

Hg1-xCdxI2 20-25 micrometers-thick layers were grown by vapor phase epitaxy on CdTe substrates in 30-100 h using an alpha-HgI2 polycrystalline source at 200-degrees C. Scanning electron microscopy and high resolution synchrotron x-ray topography studies reveal the structural defects of the vapor phase epitaxy-grown layers. Densely spaced striations and subgrain boundaries are the two main structural defects.

Published
1997

45. Dynamics of photodeformations and space charge field in photorefractive Fe:LiNbO3 studied with synchrotron area diffractometry.

Author

Calamiotou, M., Chrysanthakopoulos, N., Papaioannou, G., and Baruchel, J.

Subjects
SPACE charge, SYNCHROTRONS, ELECTRIC fields, LATTICE dynamics, PHOTOREFRACTIVE materials
Abstract

The method of synchrotron area diffractometry has been used to map with a high spatial resolution in real time the distribution over the crystal surface of the lattice deformation tensor components induced by a macroscopic visible light beam on a z-cut iron-doped photorefractive LiNbO3 crystal. The xy planes exhibit a tensile strain, on the order of 10-4, in the center and long range, extending up to 780 μm, shear deformations at the borders of the illuminated region, respectively. Photodeformations evolve with illumination time with relaxation type, time dependence, and time constants of the order of minutes. The observed lateral distribution of deformation tensor components, as well as their temporal evolution, has been examined, considering the coupling of the converse piezoelectric effect with the strong space charge field generated by the damage inducing beam along the z axis due to the bulk photovoltaic effect. The observed strain in the center can be attributed to the bulk photovoltaic field of the order of 107 V/m, while the long range shear deformations are mainly associated with the lateral components of the electric field which are present at the borders of the space charge regions. Both photodeformations and space charge field evolve at the same time scale, the dependence of time constants on the incident light intensity following the predictions of the one-center model charge redistribution due to the bulk photovoltaic effect. This work demonstrates that the method of synchrotron area diffractometry is a very powerful tool to study in situ the dynamics and spatial variation of microstuctural changes (deformations) induced by an external field (electric, magnetic, or temperature). [ABSTRACT FROM AUTHOR]

Published
2007
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49. Neutron topography

Author

Schlenker, M., Baruchel, J., Ehlers, J., editor, Hepp, K., editor, Kippenhahn, R., editor, Weidenmüller, H. A., editor, Zittartz, J., editor, Beiglböck, W., editor, Schlenker, M., editor, Fink, M., editor, Goedgebuer, J. P., editor, Malgrange, C., editor, Vieénot, J. Ch., editor, and Wade, R. H., editor

Published
1980
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