Resonant Photon-Assisted Tunneling in Van der Waals Heterostructures

We present a theory for electron tunneling in a graphene/h-BN/graphene van der Waals heterostructure under strong optical illumination. Using the Keldysh-Floquet Green’s function formalism, we have obtained the tunneling current between the graphene layers when both layers are driven periodically by an optical field. Our theory predicts that photon-assisted anti-resonance peaks are periodically developed in the tunneling current-voltage characteristic, on top of the contribution due to the dark tunneling current. We find that, while the latter originates from interband tunneling processes, the anti-resonance peaks originate from intraband tunneling processes between the Floquet subbands in different graphene layers.