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O: Oberflächenphysik

O 32: Nanostrukturen III

O 32.4: Vortrag

Donnerstag, 11. März 2004, 12:00–12:15, H38

Temperature dependence of surface morphology at grazing incidence ion bombardement on Pt(111) — •Sebastian Messlinger, Henri Hansen, Celia Polop, and Thomas Michely — I. physikalisches Institut, RWTH-Aachen, Postfach, 52056 Aachen

A Pt(111) surface is bombarded with 5 keV Ar⁺ ions under an incident angle of 83^∘ to the surface normal. The projection of the ion beam on the surface is orientated along the [112] direction, so that the ions impinge onto {111} microfacetted dense packed steps. After bombardement the surface is investigated by STM.

Using temperatures between 350 K and 720 K the experiments are carried out both in the submonolayer regime and in the multilayer regime (fluences up to 20 ML). For submonolayer fluences there are three temperature regimes with different kinds of damage patterns: for high temperatures (630 K - 720 K) the remaining vacancy islands have the energetically favoured hexagonal equilibrium shape. Going to intermediate temperatures of 450 K - 600 K long, elongated vacancy islands can be observed, which are orientated along the ion beam projection. For temperatures lower than 400 K long, branched vacancy islands appear.

Increasing the fluence to 20 ML (multilayer regime) for temperatures lower than 500 K the ion beam forms deep ripple structures with a good lateral periodicity, whereas for higher temperatures layer-by-layer erosion can be observed. The temperature dependency of the damage patterns can be understood by taking into account that the damage each ion impact produces can anneal with different rates due to the different thermally activated diffusion processes.