Single Electron Transistor with Single Aromatic Ring Molecule Covalently Connected to Graphene Nanogaps.

We report a robust approach to fabricate single-molecule transistors with covalent electrode-molecule-electrode chemical bonds, ultrashort (∼1 nm) molecular channels, and high coupling yield. We obtain nanometer-scale gaps from feedback-controlled electroburning of graphene constrictions and bridge these gaps with molecules using reaction chemistry on the oxidized graphene edges. Using these nanogaps, we are able to optimize the coupling chemistry to achieve high reconnection yield with ultrashort covalent single-molecule bridges. The length of the molecule is found to influence the fraction of covalently reconnected nanogaps. Finally, we discuss the tunneling nature of the covalent contacts using gate-dependent transport measurements, where we observe single electron transport via large energy Coulomb blockade even at room temperature. This study charts a clear path toward the assembling of ultraminiaturized electronics, sensors, and switches.