Berlin 2012 – scientific programme

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DS: Fachverband Dünne Schichten

DS 21: Micro- and nanopatterning (jointly with O)

DS 21.2: Talk

Wednesday, March 28, 2012, 12:00–12:15, H 0111

Threshold sputter depth for nanopattern formation and "zero" sputter yield ion beam irradiation of amorphous carbon — •Omar Bobes, Kun Zhang, and Hans Hofsäss — II. Phys. Institut, Uni Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

The question whether sputtering is actually needed for pattern formation by ion beam erosion is still under debate. Therefore, we investigate the minimal required sputter depth which corresponds to the transition from a flat surface to a nanostructured surface for ion energies up to 10 keV. Especially, we chose ion beam irradiation under conditions where the sputter yield approaches zero. This can be achieved by using a light substrate materials such as carbon and heavy ions with energies not exceeding 100 eV, e.g., for 100 eV Xe⁺-ions at 60^∘ angle of incidence the sputter yield is to 0.002. In order to distinguish between sputter effect and the effect of displacement of recoil atoms for the pattern formation, low energy He⁺-ion irradiation has been used and compared with Xe⁺-ion irradiation. He⁺-ions are unique, because they provide a small and almost constant sputter yield in the energy region between 500 eV and 1200 eV for amorphous carbon, but the displacement yield changes by a factor of two. One can choose the energies of Xe⁺- and He⁺-ions in such a way, either resulting in similar sputter yields or in similar displacement yield. The first results of such experiments will be presented.