Coherence Seminar: Simulation and Interpretation of Dynamical Diffraction Effects in Nanobeam Diffraction and Scattering

Start Date
01-12-2017 11:00
Room 1-10, Common Building
Speaker's name
Prof. Paul G. Evans
Speaker's institute
Department of Materials Science and Engineering, University of Wisconsin-Madison
Contact name
Sabine Schreiber
Host name
Oier Bikondoa
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X-ray nanobeam diffraction requires interpreting the scattering patterns produced using tightly focused x-ray beams.  Often the approaches employed in interpreting experimental data involve the kinematic scattering approximation, which provides excellent agreement between models and experimental data in many cases.  For systems with crystals larger than the extinction depth or thin films grown on lattice matched substrates, however, effects appear in nanobeam diffraction patterns that cannot be explained by the kinematic approach.  These include sharp lines of scattered intensity and poor agreement between predicted and observed thin film diffraction patterns in the angular range near substrate Bragg reflections.  We demonstrate an approach for including dynamical diffraction effects in nanobeam diffraction simulation that addresses these problems.  The simulation shows excellent agreement with experimental diffraction patterns in GaAs/AlGaAs heterostructures relevant to quantum information applications and allows the distortions produced in the fabrication of quantum devices to be probed quantitatively.

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