Influence of graphene-substrate interactions on configurations of organic molecules on graphene: Pentacene/epitaxial graphene/SiC

We demonstrate that molecular ordering of pentacene (Pn) on graphene depends on the interaction between graphene and its underlying SiC substrate. The adsorption of Pn molecules on zero-layer (ZL) and single-layer (SL) graphene, which were grown on a Si-faced 6H-SiC(0001) wafer, was studied using scanning tunneling microscopy (STM). Pn molecules form a quasi-amorphous layer on ZL graphene, which interacts strongly with the underlying SiC substrate. In contrast, they form a uniformly ordered layer on the SL graphene having a weak graphene-SiC interaction. Furthermore, we could change the configuration of Pn molecules on the SL graphene by using STM tips. The results suggest that the molecular ordering of Pn on graphene and the Pn/graphene interface structure can be controlled by a graphene-substrate interaction. (C) 2014 AIP Publishing LLC.