Electrolyte‐induced modulation of electronic transport in the presence of surface charge impurities on bilayer graphene

Transport properties of liquid electrolyte-gated bilayer graphene (BLG) were investigated in the presence of scattering centers introduced post-growth. The scattering centers were realized by spin-deposition of phosphine stabilized gold nanoparticles (AuNPs) of different molar concentrations (10, 20, 30, and 40 nM) directly on top of the BLG surface. Electronic transport in such samples exhibits a cluster-like scattering behavior, that is, a decrease in charge carrier mobility accompanied by a shift of the Dirac point toward negative values with increasing density of scattering centers, indicating the n-type doping of graphene by AuNPs. The characteristic resistivity-gate voltage curves show the possibility of anti-ambipolar behavior of such gated BLG films. Drude model based Kinetic Monte Carlo (KMC) simulations agree with our experimental findings and theoretically predicted behavior. Our results support the possibility of a charge carrier modulation of graphene via foreign impurity scattering introduced on its surface, as well as by the means of large electrostatic fields obtained via the liquid electrolyte gating.