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O: Fachverband Oberflächenphysik
O 29: Nanostructures at surfaces: preparation
O 29.7: Vortrag
Mittwoch, 25. März 2009, 12:00–12:15, SCH A01
Simulation of nanostructuring on sputtered surfaces by multi/rotating ion beams — •Taha Yasseri1, Reiner Kree1, and Alexander K. Hartmann2 — 1Institute for Theoretical Physics, University of Göttingen, Friedrich-Hund Platz 1, D-37075 Göttingen, Germany. — 2Institute for Physics, University Oldenburg, Carl-von-Ossietzky Strasse 9-11, D-26111 Oldenburg, Germany
Pattern formation on solid surfaces by ion beam sputtering (IBS) is intensively studied. Recent studies use continuously rotating samples or rotation with only a discrete number of directions. We have used our previously developed Monte Carlo model of IBS to systematically study these situations. For discrete directions we found: (1) either a superposition of single ion-beam patterns or a dominant pattern, depending upon the directions may be observed. (2) In the special case of two beams aligned in opposite directions, roughness of the surface decreases and movement of patterns is suppressed. A sudden change in azimuthal angle (Δ φ) of ion beam leads to a relaxation of existing ripples into a new direction. We have determined this relaxation time (τ0), which defines a characteristic angular frequency ω0=Δ φ / τ0. For rotating sample with frequency ω ω0 we found an oscillatory behavior of patterns and roughness of the surface.