Theory of Graphene-Insulator-Graphene Tunnel Junctions

Graphene–insulator–graphene vertical tunneling structures are discussed from a theoretical perspective.Momentum conservation in such devices leads to highly nonlinear current–voltage characteristics, which with gates on the tunnel junction form potentially useful transistor structures. Two prior theoretical treatments of such devices are discussed; the treatments are shown to be formally equivalent, although some differences in their implementations are identified. The limit of zero momentum conservation in thetheory is explicitly considered, with a formula involving the density-of-states of the graphene electrodesrecovered in this limit. Various predictions of the theory are compared to experiment.