New carbon-based materials and nanopatterning of carbon surfaces
Our activities are focused on various CVD-based technologies which allow fabrication of new carbon materials with intentionally predefined unique physical properties. The common denominator of the procedures applied is the interaction of gas-phase molecules with various substrates under high-temperature regimes. All methods are fully ultra-high-vacuum compatible and enable to study elementary processes of relevance for material engineering and catalysis. Usually the molecular carriers of carbon atoms decompose on hot substrate and these events initialize the desired growth of a new carbon material. One example of the successfully applied strategy was the high-temperature methane infiltration of felts consisting of SWCNT (singly walled carbon nanotubes) [[i]] (see Fig.2). By exploiting the oxygen-etching of Ga+-FIB-prestructured highly-oriented pyrolythic graphite (EFIB) it was possible to fabricate macroscopically sized material consisting of periodically arranged stacks of graphene layers (nG) [[ii][iii]]. Preliminary experiments reveal a high technological capability of such material towards addressed printing of single nG sheets on insulating substrates.
Fig. 2a Late infiltration stage of SWNT felts by CH4/H2 mixture.
Fig. 2b Azomethane-induced growth of 2D graphene layers pinned by nano-cavities in HOPG.
Fig. 2c Array of formatted graphene stacks created by applying EFIB procedure.
[i] A. Böttcher, F. Hennrich, H. Rösner, S. Malik, M.M. Kappes, S. Lichtenberg, G. Schoch, O. Deutschmann, Growth of novel carbon phases by methane infiltration of free-standing single-walled carbon nanotube films, Carbon, 45, 1085 (2007)
[ii] A. Böttcher, M. Heil, N. Stürzl, S.-S. Jester, S. Malik, F. Pérez-Willard, P. Brenner, D. Gerthsen and M.M. Kappes, Nanostructuring the graphite basal plane by focused-ion-beam patterning and oxygen etching, Nanotechnology, 17, 5889 (2006)
[iii] A. Böttcher, D. Löffler, N. Bajales, S. Ulas, R. Machatschek, S. Malik, P. Brenner, M. M. Kappes, Arrays of uniformly shaped blocks of stacked graphene sheets, Nanotechnology 23, 415302 (2012)