Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 68: Semiconductor substrates: Epitaxy and growth

O 68.2: Vortrag

Donnerstag, 25. März 2010, 10:45–11:00, H42

Real Time Measurements of Surface Diffusion in a Multi-Reconstruction System: Ag/Si(111) — •Dirk Wall¹, Ingo Lohmar², Kelly Ryan Roos³, Joachim Krug², Michael Horn-von Hoegen¹, and Frank-Joachim Meyer zu Heringdorf¹ — ¹Fakultät Physik und Center for Nanointegration Duisburg-Essen (CeNIDE), Universität Duisburg-Essen, 47057 Duisburg, Germany — ²Institut für Theoretische Physik, Universität zu Köln, 50937 Köln, Germany — ³Department of Physics, Bradley University, Peoria, Il 61625, USA

Photoemission Electron Microscopy (PEEM) is used to study the thermal decay (750-850°C) of Ag islands grown on Si(111) surfaces. During decay, Ag atoms are expelled from the island edges and migrate over the surface. Due to continuous desorption, a coverage gradient forms around each island. Depending on local Ag coverage, two different concentric reconstructions form. These reconstructed "isocoverage zones" are imaged with PEEM. A simple continuum model is presented explaining the dynamic decay of the islands for multi-reconstruction systems. Using this model, we extract diffusion parameters for the specific areas in one simple desorption experiment. We demonstrate that the imaging of these reconstructed "isocoverage zones" constitutes a unique experimental method for directly imaging diffusion fields in epitaxial systems. The general applicability of this imaging technique is demonstrated by the decay of other metal islands on Silicon surfaces of various orientations.