Transport properties of electrolyte gated graphene devices

Graphene is a single layer of carbon atoms arranged in a honeycomb lattice. It is the building block of graphite. The latter is made out of weakly coupled (van der Waals force) graphene layers stacked one on the other. Graphene was isolated in 2004 through micro-mechanical cleavage of graphite. The interaction between lattice and charge carriers produces a linear electronic dispersion relation. Therefore, the charge carriers in graphene mimic chiral particles with zero mass. Many interesting physical properties were shown in graphene including room temperature integer quantum Hall effect, fractional quantum Hall effect, high temperature ballistic transport, and Hofstadter's butterfly. Superconductivity is predicted in graphene at extremely high carrier concentrations, but it has never been experimentally proven. Electrolyte gating allows inducing high charge carrier concentration in a wide range of materials. These achievable densities are one order of magnitude lower than chemical doping, but two orders of magnitude higher than classic solid gating. Contrary to chemical doping, electric field induced charges do not affect the crystal structure of the studied material. In multilayer graphene also intercalation of ions in between the graphene planes is conceivable in electrolyte gated devices. It causes changes in the physical properties of graphene.