Influence of surface curvature in the process of solid-state dewetting of polycrystalline silver layer on amorphous silica

Solid-state dewetting has been gaining more and more interest in the past few years, as it was identified as a potential synthesis method of nanostructures[1,2]. Dewetting tends to transform metastable or unstable thin films into isolated nanoparticles. The transformation is ensured by solid-state diffusion. Different diffusion pathways were identified: surface [3], but also interface or grain boundary [4,5]. The prominent model to explain this diffusion is based on the analysis of the chemical potential, which increases along the local curvature of the surface.

We study the solid-state dewetting of thin polycrystalline silver layers on amorphous silica. Thanks to in-situ and real time SEM imaging (as used in [6]), and image processing, we were able to measure for each point of the front the local speed and curvature. We show that the surface curvature cannot explain the local transformations observed during dewetting, since the maximum rates are observed precisely where the in-plane curvature compensates the out-of-plane curvature. The understanding of this phenomenon needs to take into account the polycrystalline nature of the dewetting material.

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[3] A.E.B. Presland, G.L. Price, D.L. Trimm, T. Heath, Surface Science 29 (1972) 424–434.

[4] G. Atiya, V. Mikhelashvili, G. Eisenstein, W.D. Kaplan, Journal of Materials Science 49 (2014) 3863–3874.

[5] A. Kosinova, L. Klinger, O. Kovalenko, E. Rabkin, Scripta Materialia 82 (2014) 33–36.

[6] P. Jacquet, R. Podor, J. Ravaux, J. Teisseire, I. Gozhyk, J. Jupille, R. Lazzari, Scripta Materialia 115 (2016) 128–132.