Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 71: Metal substrates: Epitaxy and growth

O 71.11: Talk

Thursday, March 25, 2010, 17:30–17:45, H31

Oblique incidence ion impact pattern formation on Cu(001) along the [100] and [110] azimuthal directions — •Frank Everts, Herbert Wormeester, and Bene Poelsema — Solid State physics, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands

Oblique incidence sputtering is a versatile tool for nanopattern creation on different types of surfaces. Often ripple patterns are observed as a result of an erosion instability. The orientation of the ripples is governed by the polar angle of incidence of the ion beam. High resolution low energy electron diffraction reveal an unanticipated azimuth dependence for Cu(001) at 200 K. Near normal incidence sputtering along [110] gives rise to a diffraction pattern showing a fourfold symmetry of the etch structures. Surprisingly, a further increase of the polar angle shows that this surface imposed fourfold symmetry is preserved up to grazing incidence. In marked contrast are the results for sputtering along the [010] azimuth. Already for near normal incidence the fourfold symmetry in the diffraction pattern is broken, reflecting ripple formation. The orientation of these ripples changes with more oblique incidence sputtering. The explanation for this strong azimuth sensitivity is found by varying the ion energy, showing a strong dependence on the details of the ion substrate interaction.