The determination of the three-dimensional dislocation structure, i.e. the configuration and nature of the dislocations, in silicon by synchrotron white X-ray topography combined with a topo-tomographic technique is demonstrated. A [001]-oriented CZ-Si crystal of diameter approximately 7 mm was fixed on a subsidiary goniometer with three rotation axes (omega, Rx, Ry) and x-y-z stages, keeping its growth axis parallel to the omega-axis. This goniometer was mounted on the swivel stage of the main diffractometer installed at the experimental hutch of beamline BL28B2 of SPring-8. After adjusting the (110) plane to be perpendicular to the incident white X-ray beam by observing transmission Laue patterns, the crystal was inclined by 4.3 degrees so that the 004 Laue spot could be formed by 60 keV X-rays. Laue topographs observed by rotating the omega-axis of the subsidiary goniometer were recorded using X-ray films and a cooled CCD camera. The direction of the dislocation lines, Burgers vectors and glide planes were determined by following the variation in features of the dislocation images in the 004 Laue spot and by examining the contrast of the dislocation images in the Laue spots concerning the [111] and [022] planes. It is concluded that white X-ray topography combined with the omega-rotation technique is useful for clarifying the three-dimensional dislocation structure.

Two topography experimental stations are presently available at SPring-8. The first, constructed at the short-length bending magnet beam line BL28, is designed to perform white- and selected wide-energy-range x-ray topography. The other is a high-resolution diffraction topography station located on the medium-length bending magnet beam line BL20, where the incoming beam displays a large cross section and high degree of parallelism. This allows us to observe fine structures of three-dimensionally large crystals used in industry if high energy is employed. The construction concepts, as well as first, selected experimental results are presented.

We developed a compact synchrotron X-ray topography system equipped with a demountable Si channel-cut crystal monochromator with an energy range of 5-20 keV at beamline 09A in SAGA Light Source (SAGA-LS) to enable switching between a white X-ray beam and a monochromatic X-ray beam. The position of incidence of the X-ray beam on the sample is kept constant because the beam-path difference, which is caused by inserting the monochromator and by tuning the X-ray energy, is adjusted automatically. Two possible applications of this system are proposed: (1) the observation of dislocations in a thick Si rod by white X-ray topography, and (2) a comparative study of X-ray images of defects and strain in a 4H-SiC wafer captured using white and monochromatic X-ray beams.

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