Graphene-based tunnel junction

The tunneling current in a junction formed by graphene half-planes and bilayer graphene with two possible packing types and two possible orientations of the crystal lattice is calculated by the Green’s function technique in the framework of the tight-binding approximation. It is shown that the band structure of graphene oriented toward the junction by the armchair-type edges leads to a power-law dependence of the tunneling current on applied voltage being specific for each specific kind of graphene. The characteristic features of this dependence are determined by the change in the number of transport channels with the growth of the applied voltage. For all junctions under study with zigzag edges oriented toward each other, it is found that the tunneling current exhibits characteristic peaks related to the existence of the localized edge states. The effects induced by the gate voltage are also studied. For the structures with zigzag edges, it is shown that the effect of switching off/on takes place for the junctions. The junctions formed by the graphene armchair edges do not exhibit any pronounced switching phenomena and the growth of the bias voltage results in higher values of the conductivity.