Influence of surface defects on superlattice patterns in graphene on graphite

摘要

Superstructures observed by scanning tunnelling microscopy on graphite have been reported several decades ago, but the interest in these superstructures recently intensified due to their occurrence in graphene grown on different substrates. Generally accepted explanation of origin of these superstructures is an overlap of disoriented top layer of graphite and the underlying graphite single crystal, which causes moire pattern. Here we present experimental findings that the orientation of the superstructure is influenced by surface defects and edges of graphene. Superstructures in graphene put on graphite exist even if the graphene is not supported by graphite over its entire area. The modulation of the density of states influences the strength of intra-layer carbon bonds in such a way that the graphene breaks along the superstructure minima. The tunnelling conductance of the areas with superstructures is enhanced with regard to bulk graphite. (C) 2016 Elsevier B.V. All rights reserved.