C60 on SiC nanomesh

A SiC nanomesh is used as a nanotemplate to direct the epitaxy of C-60 molecules. The epitaxial growth of C-60 molecules on SiC nanomesh at room temperature is investigated by in situ scanning tunneling microscopy, revealing a typical Stranski-Krastanov mode (i.e., for the first one or two monolayers, it is a layer-by-layer growth or 2-D nucleation mode; at higher thicknesses, it changes to island growth or a 3-D nucleation mode). At submonolayer (0.04 and 0.2 ML) coverage, C60 molecules tend to aggregate to form single-layer C-60 islands that mainly decorate terrace edges, leaving the uncovered SiC nanomesh almost free of C-60 molecules. At 1 ML C-60 coverage, a complete wetting layer of hexagonally close-packed C-60 molecules forms on top of the SiC nanomesh. At higher coverage from 4.5 ML onward, the C-60 stacking adopts a (111) oriented face-centered-cubic (fcc) structure. Strong bright and dim molecular contrasts have been observed on the first layer of C-60 molecules, which are proposed to originate from electronic effects in a single-layer C-60 island or the different coupling of C-60 molecules to SiC nanomesh. These STM molecular contrast patterns completely disappear on the second and all the subsequent C-60 layers. It is also found that the nanomesh can be fully recovered by annealing the C-60/SiC nanomesh sample at 200 degrees C for 20 min.