C60 on SiC Nanomesh

Abstract

A SiC nanomesh is used as a nanotemplate to direct the epitaxy of C₆₀ molecules. The epitaxial growth of C₆₀ 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 C₆₀ islands that mainly decorate terrace edges, leaving the uncovered SiC nanomesh almost free of C₆₀ molecules. At 1 ML C₆₀ coverage, a complete wetting layer of hexagonally close-packed C₆₀ molecules forms on top of the SiC nanomesh. At higher coverage from 4.5 ML onward, the C₆₀ stacking adopts a (111) oriented face-centered-cubic (fcc) structure. Strong bright and dim molecular contrasts have been observed on the first layer of C₆₀ molecules, which are proposed to originate from electronic effects in a single-layer C₆₀ island or the different coupling of C₆₀ molecules to SiC nanomesh. These STM molecular contrast patterns completely disappear on the second and all the subsequent C₆₀ layers. It is also found that the nanomesh can be fully recovered by annealing the C₆₀/SiC nanomesh sample at 200 °C for 20 min.