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Struktur und Dynamik Poster: Mi., 14:00–16:30 M-P119
Dewetting of thin solid films under swift heavy ion irradiation
Thunu Bolse 1 , Mirco Kreis 1 , Hartmut Paulus 1 , Klara Lyutovich 2 , Wolfgang
Bolse 1
1 Institut für Strahlenphysik, Universität Stuttgart – 2 Institut für Halbleitertechnik,
Universität Stuttgart
Incomplete wetting or dewetting plays an important role in thin film systems, be it for
the growth of the film, its stability or chemical reactions and phase formation taking
place at the interface. Dewetting usually occurs when the film is in its liquid state or
at least near to its melting point (in case of glasses). Here we report about our recent
observation that dewetting also may occur when a thin metal oxide film (NiO, Fe2O3,
TiO2, some tens of nm thicknes) grown on untreated Si-substrate is bombarded with
swift heavy ions, even when the film is kept at liquid nitrogen temperature. Similar to
what was observed in case of thin molten polymer films [1] we could identify heterogeneous
and homogeneous nucleation taking place at the beginning of the dewetting
process. Dewetting then proceeds by the formation and growth of circular holes with
the removed material piling up in a rim around these holes. By coalescence of the
holes narrow ridges are formed, which finally decay into small droplets because of the
Rayleigh-Plateau instability. Different techniques like SEM, AFM and RBS were used
to analyse the dewetting processes and nucleation mechanisms that occur during the
ion bombardment. We have investigated the basic kinetics involved in these phenomena
by studying the development of the dewetting patterns as a function of different
ion species and energies and the applied fluences as well as their dependence on the
film thicknes.
[1] S. Herminghaus, et al., Science 282 (1998) 916