Graphene Logic Gates

Graphene is a biocompatible material that can be incorporated safely into living tissue. This property makes graphene an ideal material for bioelectronics applications. The main obstacle for using graphene as a material for bioelectronic circuits is the lack of a bandgap, which results in noneffective current switching. Here, we use rectangular L-shaped graphene nanoribbons as a building block for graphene logic gates. Electrons are initially transported along the zigzag-edged nanoribbon and then the transport direction changes by 90 degrees, resulting in transport along the armchair edge. Our computations showed that electron scattering because of this change in the direction causes the appearance of a pseudobandgap, which is large enough for logic operations. This pseudobandgap appears as a zero-conductance region for electron energies near the Fermi level. We propose an AND, an OR, and a NOT logic gate and use tight-binding Hamiltonians and nonequilibrium Greens functions to show that these designs can reproduce effectively the desired logic operations.