Bilayer Graphene Quantum Dot Defined by Topgates

TL;DR

This paper demonstrates a method to define quantum dots in bilayer graphene using nanoscale topgates, revealing conductance suppression at low temperatures and Coulomb blockade oscillations, advancing graphene-based quantum device fabrication.

Contribution

It introduces a novel topgate technique to create quantum dots in bilayer graphene, enabling precise control of resistive regions and quantum confinement.

Findings

Conductance suppressed below 500 mK under grounded gates

Quantum dot exhibits Coulomb blockade oscillations

Gate layout effectively defines resistive regions

Abstract

We investigate the application of nanoscale topgates on exfoliated bilayer graphene to define quantum dot devices. At temperatures below 500 mK the conductance underneath the grounded gates is suppressed, which we attribute to nearest neighbour hopping and strain-induced piezoelectric fields. The gate-layout can thus be used to define resistive regions by tuning into the corresponding temperature range. We use this method to define a quantum dot structure in bilayer graphene showing Coulomb blockade oscillations consistent with the gate layout.