Carrier Control of Graphene Driven by the Proximity Effect of Functionalized Self-assembled Monolayers

We demonstrated the carrier control of graphene by employing the electrostatic potential produced by several types of self-assembled monolayer (SAM) formed on SiO₂ substrates. For single layer graphene on perfluoroalkylsilane-SAM, the stiffening of the Raman G-band indicates a large down shift of the Fermi level (∼−0.8 eV) by accumulated hole carriers. Meanwhile, aminoarylsilane-SAM accumulated electron carriers, which compensate the hole carriers doped by adsorbed molecules under the ambient atmosphere, in graphene. The present results and their theoretical analysis reveal that the use of the dipole moments of SAM molecules can systematically modulate the electrostatic potential affecting graphene without destroying its intrinsic electronic structure and let us know that the proximity effect of the SAMs is a promising way in developing graphene-based solid state electronics.