Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 24: Postersitzung (Epitaxie und Wachstum, Oxide und Isolatoren, Elektronische Struktur, Oberfl
ächenreaktionen, Adsorption an Oberfl
ächen, Organische Dünnschichten)
O 24.55: Poster
Mittwoch, 26. März 2003, 14:30–17:30, P1
Electronic structure and surface stress of partially H-covered Si(001) — •J. van Heys, P. Kury, M. Horn-von Hoegen, and E. Pehlke — Fachbereich Physik, Universität Essen
Surface stress characterizes the change of energy of a surface in response to an elastic strain. The surface-stress anisotropy gives rise to the interaction of mono-atomic steps on Si(001), which is responsible for surface morphology on mesoscopic length scales. Moreover, comparison of stress for various surface configurations yields valuable insight into the electronic and geometric structure of the surface.
Applying density functional theory, we have calculated the surface stress tensor of Si(001) surfaces partially covered with hydrogen. Within the p(2x2) surface unit-cell all possible configurations for H-coverages equal to 0, 1/4, 1/2, and 1 ML have been considered. Parallel to the dimer bond the surface stress turns out to be always tensile. It varies only little, staying roughly in the range of 60 - 80 meV/Å2. Perpendicular to the dimer bond the variation is larger, what makes this direction better suited for measurements using single-domain vicinal Si(001) surfaces. SSIOD (surface stress induced optical deflection) experiments are currently carried out.