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Nanoscale patterning of  metal-dielectric overlayers: from surface ripples to nanowires

Francesco Buatier de Mongeot 1,2Andrea Toma 1,2Daniele Chiappe 1,2Corrado Boragno 1,2Ugo Valbusa 1Barbara Šetina 3Matjas Godec 3Monika Jenko 3

1. Dipartimento di Fisica (DIFI), Via Dodecaneso, 33, Genova 16146, Italy
2. CNISM Unità di Genova (CNISM), Via Dodecaneso, 33, Genova 16146, Italy
3. Insitute of metals and technology (IMT), Lepi pot 11, Ljubljana 1000, Slovenia

Abstract

Thin solid films appear most commonly in polycrystalline form, which means that they have highly constrained single-crystalline grains. Polycrystalline films are used in a large variety of  devices, such as magnetic storage media, catalytic and thermal elements, protective coatings.  It is thus desirable to extend to polycrystalline films, the approaches which have been developed for the self-organized formation of nanostructures on single-crystalline metal substrates [1].

We report on the formation of periodic metal nanostructures induced by self-organized sputtering processes of polycrystalline metal films supported on dielectric substrates. These results qualitatively agree with the behaviour reported for off–normal sputtering experiments on single-crystal metals where periodic ripples endowed with wavelengths in the 10 nm range are observed [2].

At variance with the latter case, we found that a non-singular starting surface morphology does plays a critical role in guiding self-organization during the early stages, where the hierarchical distribution of polycrystalline grains imposes a non-stochastic spatial modulation of the ion impact sites.

We also discuss the role of grain boundaries in this self-organization process: although providing an additional bias for diffusion of mobile defects ona 100 nm scale, they do not limit the propagation of nanoscale ripples which extend for several micrometers across the individual grains .

[1] U. Valbusa et al., J. Phys. Condens. Matter 14 (2002) 8153

[2]A. Toma, D. Chiappe, B. Šetina Batič, M. Godec, M. Jenko,  F. Buatier de Mongeot, submitted

 

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Related papers

Presentation: Poster at E-MRS Fall Meeting 2008, Symposium B, by Francesco Buatier de Mongeot
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-19 23:05
Revised:   2009-06-07 00:48