Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 33: Symposium: Frontiers of Surface Sensitive Electron Microscopy I (Invited Speakers: James Hannon, Raoul van Gastel, Thomas Schmidt)

O 33.3: Vortrag

Dienstag, 26. Februar 2008, 14:45–15:00, MA 005

Real Time Imaging of Surface Diffusion Fields during Island decay — •Dirk Wall¹, Kelly R. Roos^1,2, Kimberly L. Roos¹, Ingo Lohmar³, Joachim Krug³, Michael Horn-von Hoegen¹, and Frank-J. Meyer zu Heringdorf¹ — ¹Department of Physics and Center for Nanointegration Duisburg-Essen (CeNIDE) Universität Duisburg-Essen, D-47057 Duisburg, Germany — ²Department of Physics, Bradley University, Peoria, IL 61625, USA — ³Institut für Theoretische Physik, Universität zu Köln, 50937 Köln, Germany

Photoemission Electron Microscopy (PEEM) is used to study the thermal decay (650^∘C - 850^∘C) of Ag islands grown epitaxially on flat and vicinal Silicon surfaces. During island decay, bright quasi static Ag-reconstructed zones are formed around each of the islands. Micro Low Energy Electron Diffraction (µ-LEED) reveals that the photoemission contrast is caused by different reconstructions due to a coverage gradient that extends outward from the edge of the islands. A simple continuum model is presented explaining the dynamic decay of the islands. We additionally studied the diffusion anisotropy on numerous vicinal Silicon surfaces. The degree of diffusion anisotropy of the system is thereby revealed by the shape of the zones. We demonstrate that the imaging of these reconstructed "isocoverage-zones" constitutes a unique experimental method for directly imaging diffusion fields and diffusion anisotropy in epitaxial systems. The general applicability of this imaging technique is demonstrated by the decay of Indium islands on Silicon.