Phonon-assisted resonant tunneling of electrons in graphene-boron nitride transistors

TL;DR

This study reports sharp resonant features in the conductance of graphene-boron nitride-graphene transistors, attributed to phonon-assisted electron tunneling, independent of carrier density and linked to phonon density of states.

Contribution

It provides experimental evidence of phonon-assisted resonant tunneling in graphene heterostructures, identifying specific phonon energies involved.

Findings

Resonant conductance features are insensitive to gate voltage.

Resonances align with peaks in phonon density of states.

Phonon energies match lattice dispersion curves.

Abstract

We observe a series of sharp resonant features in the differential conductance of graphene-hexagonal boron nitride-graphene tunnel transistors over a wide range of bias voltages between $\sim$10 and 200 mV. We attribute them to electron tunneling assisted by the emission of phonons of well-defined energy. The bias voltages at which they occur are insensitive to the applied gate voltage and hence independent of the carrier densities in the graphene electrodes, so plasmonic effects can be ruled out. The phonon energies corresponding to the resonances are compared with the lattice dispersion curves of graphene-boron nitride heterostructures and are close to peaks in the single phonon density of states.