Resistance modulation of multilayer graphene controlled by the gate electric field

A simple and effective top gate fabrication was realized to construct a dual-gate structure on graphene. In addition to the SiO2/highly doped Si bottom gate, an aluminum layer was directly deposited on the graphene, followed by natural oxidation in the atmosphere, to form the top gate and dielectric layer underneath. Electric field modulation between the top and bottom gates was investigated in multilayer graphene (MLG) with different thicknesses, which enabled us to estimate the screening effect in the MLG. A thickness-dependent charge-neutrality-resistance peak shift was observed and clarified in terms of the inter-layer screening length to the electric field in the dual-gate structure. A screening length of 1.2 nm, corresponding to the thickness of three- or four-layer graphene, was experimentally estimated