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

摘要

Pentacene has been used widely in organic devices, and the interfacestructure between pentacene and a substrate is known to significantly influencedevice performances. Here we demonstrate that molecular ordering of pentaceneon graphene depends on the interaction between graphene and its underlying SiCsubstrate. The adsorption of pentacene molecules on zero-layer and single-layergraphene, which were grown on a Sifaced 6H-SiC(0001) wafer, was studied usingscanning tunneling microscopy (STM). Pentacene molecules form a quasi-amorphouslayer on zero-layer graphene which interacts strongly with the underlying SiCsubstrate. In contrast, they form a uniformly ordered layer on the single-layergraphene having a weak graphene-SiC interaction. Furthermore, we could changethe configuration of pentacene molecules on the singlelayer graphene by usingSTM tips. The results suggest that the molecular ordering of pentacene ongraphene and the pentacene/graphene interface structure can be controlled by agraphene-substrate interaction.