Structured HOPG surfaces as a source of tailored nanographene sheets

ARTUR BÖTTCHER; DANIEL LÖFFLER; NOELIA BAJALES; SHARALI MALIK; PATRICE BRENNER; DAGMAR GERTHSEN; MANFRED M. KAPPES

Assergi

Workshop; Graphita; 2011

Gran Sasso National Laboratories

The focused ion beam technique, Ga+-FIB, followed by high-temperature oxidation has been applied to fabricate arrays of well defined periodic structures on HOPG surfaces [1]. The reactive structuring method exploits the high probability of amorphous carbon to be gasified in the oxidation reaction. Large surface areas (5 x 5 mm) covered by periodically arranged nanocavities, gratings and arrays of nm-sized cube-like blocks have been fabricated routinely. The latter represent stacks of square-shaped nG sheets in quantities of up to 1012 cm-2 and can be created with mean fabrication rates of ~106 nG/cm2s. Under optimal patterning conditions, the rectangular blocks of stacked nG sheets can be routinely fabricated with a mean efficiency of ~10-10 C/O2.SEM images of the large patterned areas evidence considerable amounts of nG sheets decoupled from the substrate. We tentatively assigned this effect to electric charging induced by exposing the surface to the electron beam. This exfoliation procedure appears more efficient when increasing the nG-nG spacing in the blocks by intercalated C60 molecules. In both cases we observed a spontaneous bunching of the exfoliated sheets. [1] A. Böttcher et al. Nanotechnology 17(2006)5889