Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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Directionality and energetics of the metal-induced crystallization of amorphous carbon thin filmsJanke, D.; Wüstefeld, C.; Julin, J. A.ORC; Hübner, R.; Grenzer, J.; Gemming, S.ORC; Rafaja, D.; Krause, M.ORC
The catalytic graphitization with layer exchange (LE) of amorphous carbon in thin film stacks with Ni was investigated as a function of the initial stacking order. Bilayer and triple layer stacks were exposed to heating ramps up to 700 °C. Raman spectroscopy showed the formation of a layered graphitic structure after the annealing.
During outwards LE, as C is transported towards the sample surface, a smooth layer with graphitic planes parallel to the interface with the substrate has formed through a 2D growth. A significant restructuring of the Ni layer appeared during inwards LE, as C is transported towards the substrate. Here, the fragmentation of the Ni layer, as well as the regions with turbulence-like and folding defects indicated a 3D growth.
The degree of LE, quantified by ion beam analysis, is 95 % and 80 % for the outand inwards direction, respectively. Based on the calculation of surface and interface energies of the initial and final states, thermodynamic estimations pointed to the wetting of Ni grain boundaries by C atoms as the initial driving force for the LE and allowed a consistent understanding of the LE directionality and of the final thin film microstructure.
International Winterschool on Electronic Properties of Novel Materials - Molecular Nanostructures, 09.-16.03.2019, Kirchberg, Österreich
MRS Spring Meeting & Exhibition, 22.-26.04.2019, Phoenix, USA