Electronic structure of a graphene superlattice with massive Dirac fermions

TL;DR

This paper investigates how a periodic potential affects the electronic structure of graphene with an energy gap, revealing tunable band gaps and anisotropic Fermi velocities, with implications for electronic device applications.

Contribution

It introduces a theoretical analysis of a graphene superlattice with a substrate-induced gap, showing the emergence of extra Dirac points and tunable electronic properties.

Findings

Extra Dirac points appear under certain conditions.

Energy gap can be tuned from 0 to 2Δ.

Effective Fermi velocity is highly anisotropic.

Abstract

We study the electronic and transport properties of a graphene-based superlattice theoretically by using an effective Dirac equation. The superlattice consists of a periodic potential applied on a single-layer graphene deposited on a substrate that opens an energy gap of $2\Delta$ in its electronic structure. We find that extra Dirac points appear in the electronic band structure under certain conditions, so it is possible to close the gap between the conduction and valence minibands. We show that the energy gap $E_g$ can be tuned in the range $0\leq E_g \leq 2\Delta$ by changing the periodic potential. We analyze the low energy electronic structure around the contact points and find that the effective Fermi velocity in very anisotropic and depends on the energy gap. We show that the extra Dirac points obtained here behave differently compared to previously studied systems.