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Æü»þ: 2012-01-26 16:00 - 18:00
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Ï¢ÍíÀè: ÃæÈø͵§4868
¹Ö±é¼Ô: Dr. Sergey SUTURIN  (Ioffe Physical Technical Institute, St. Petersburg, Russia)
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¥¢¥Ö¥¹¥È¥é¥¯¥È: Design of novel materials for micro and nano-electronics requires application of appropriate characterization methods for analyzing crystal structure, lattice perfection and morphology of the fabricated samples. As the time goes by, the individual components of electronic and magnetic devices get smaller and smaller, while the size and boundary effects in these components become more and more important. While various direct space techniques are available for morphological studies at nanometer scale, these techniques are usually ex-situ and are often destructive to the sample. X-ray and electron diffraction methods are known to be very suitable not only for non-destructive study of crystal structure but also for investigating crystal termination planes, domain boundaries and correlations in nanoparticles distribution. These investigations require going beyond the Bragg reflection core so that a wider range of reciprocal space is explored. Reflection shape, appearance of streaks stretching out, presence of multiple reflection cores becomes important. Therefore it is very challenging to be able to record 3D intensity distribution in vicinity of Bragg reflections, along the streaks and anywhere else in the reciprocal space. With the development of 2D detectors three-dimensional mapping becomes more and more conventional in X-ray diffraction as well as in grazing incidence small angle X-ray scattering (GISAXS). However, very few reports exist so far on 3D imaging using high-energy electron diffraction (RHEED). The latter technique is one of the few to be used directly during the sample growth and is affordable in the lab with no requirement for costly synchrotron radiation experiments. In this presentation the 3D imaging approach using both X-rays and electrons will be demonstrated following the diffraction studies in Co / MnF2 / CaF2 / Si system. The data obtained is supposed to be relevant for understanding faceting, strain distribution and lattice perfection in nanoscale epitaxial heterostructures. New technique for taking and processing three-dimensional RHEED data will be presented.

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