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O: Fachverband Oberflächenphysik

O 15: Methods: Other Experimental Techniques I

O 15.2: Vortrag

Montag, 25. Februar 2008, 15:45–16:00, MA 041

Static speckle experiments using white synchrotron radiation — •Tushar Sant, Tobias Panzner, and Ullrich Pietsch — Solid State Physics Group, University of Siegen, 57068 Siegen, Germany

Static speckle experiments were performed using coherent white X-ray radiation from a bending magnet at BESSYII. Semiconductor and polymer surfaces were investigated under incidence condition smaller than the critical angle of total external reflection. The scattering pattern of the sample results from the illumination function modified by the surface undulations [1]. The periodic oscillations are caused by the illumination function whereas other irregular features are associated with sample surface. The speckle map of reflection from a laterally periodic structure like GaAs grating is studied [2]. Under coherent illumination the grating peaks split into speckles because of fluctuations on the sample surface. It is important to understand which length scales on the sample surface are responsible for the oscillations in reflectivity map. To investigate this experiments are done with a triangular shaped sample. Different parts of the sample are illuminated with the footprint on the sample larger or smaller than the actual sample length. This gives prior information about total illuminated area on the sample. Using this additional information a detailed surface profile of the sample is reconstructed.1. Pietsch U, et al. Physica B- Condensed Matter, 357 (2005) 45. 2. Panzner T, et al. Thin Solid Films, 515 (2007) 5563.