Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 66: Nanostructures at Surfaces VI (Surface Reconstructions)

O 66.3: Vortrag

Freitag, 30. März 2007, 10:45–11:00, H36

Static Speckle Experiments with White Synchrotron Radiation — •Tushar Sant¹, Tobias Panzner¹, Wolfram Leitenberger², Gudrun Gleber¹, and Ullrich Pietsch¹ — ¹Solid State Physics, University of Siegen, 57068 Siegen, Germany — ²Institute of Physics, University of Potsdam, 14415 Potsdam, Germany

Static speckle experiments were performed using white synchrotron radiation at EDR beamline at BESSY-II. It has been shown that for coherent scattering experiments in reflection geometry the knowledge of the illumination function incident on the sample is important[1]. In order to prove the inter play between the illumination function and a real sample the coherent reflectivity has been recorded from the surface of technologically smooth GaAs wafer. Besides periodic oscillations which are caused by the scattering from incident pinhole other features appear which are associated with the sample surface profile. The illumination function calculated by means of Lommel formalism matches well with the measured function and will be used for further surface reconstruction from speckle maps. For further examination speckle map of reflection from a laterally periodic structure like GaAs grating is studied [2]. Under coherent illumination the grating peaks split into speckles which correspond to fluctuations on the sample surface. The surface morphology of the grating is reconstructed from this coherent scattering so as to determine local height fluctuations. 1.Pietsch U, et al. Physica B- Condensed Matter, 357 (2005) 45. 2.Pietsch U, et al. Physica B- Condensed Matter, (2007) in press.