Dresden 2014 – scientific programme
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DS: Fachverband Dünne Schichten
DS 47: Micro- and Nanopatterning (jointly with O)
DS 47.3: Talk
Friday, April 4, 2014, 10:00–10:15, CHE 89
Nano-structured surfaces produced by low energy ion beam sputtering of amorphous FexSi1−x films — •Kun Zhang, Christoph Brüsewitz, and Hans Hofsäss — II. Physikalisches Institut, Universität Göttingen, Göttingen, Germany
It is well known that metallic surfactants induce pronounced dot and ripple patterns on Si substrate surfaces during normal ion incidence sputter erosion. These surfactant atoms are co-deposited on the substrate surface either from intentional co-deposition or inadvertently contaminations from sputtering of the vacuum chamber walls. In the present contribution we investigate the pattern formation on amorphous FexSi1−x thin films with different Fe atomic fraction x, irradiated with Xe ions of 5 keV and 10 keV energies and normal incidence. In this situation the Fe atoms work as surfactants, but are supplied from the bulk of the substrate. The resulting surface morphologies were examined ex-situ by AFM, while the Fe concentration and its depth profile were determined with RBS and high resolution RBS. Nanopattern forms on the substrates with x = 0.02 - 0.08. In this case Fe atoms accumulate in the surface near region ( 13 nm in depth) after ion irradiation, revealing a phase separation towards a FeSi2 phase. For the samples with x >0.09, the average Fe concentration near the surface exceeds x=0.33 and the surface remains flat. For x <0.02 no pattern formation occurs. The results give further evidence of phase separation as a major drive force for surfactant induced the pattern formation.