Gate Defined Quantum Confinement in Suspended Bilayer Graphene

TL;DR

This paper introduces a method to create quantum confined structures in suspended bilayer graphene using external electric fields, avoiding edge and substrate disorder, and demonstrates controlled single-electron transport suitable for advanced nanoelectronic applications.

Contribution

The authors develop a technique for quantum confinement in suspended bilayer graphene via electric fields, eliminating edge and substrate disorder effects.

Findings

Quantum dot formation at zero magnetic field using electric field-induced energy gap.

Quantum dot formation at high magnetic field using quantum Hall ferromagnet gap.

Electrostatic simulations confirm local control over graphene's band structure.

Abstract

Quantum confined devices that manipulate single electrons in graphene are emerging as attractive candidates for nanoelectronics applications. Previous experiments have employed etched graphene nanostructures, but edge and substrate disorder severely limit device functionality. Here we present a technique that builds quantum confined structures in suspended bilayer graphene with tunnel barriers defined by external electric fields that break layer inversion symmetry, thereby eliminating both edge and substrate disorder. We report clean quantum dot formation in two regimes: at zero magnetic field B using the single particle energy gap induced by a perpendicular electric field and at B > 0 using the quantum Hall ferromagnet {\nu} = 0 gap for confinement. Coulomb blockade oscillations exhibit periodicity consistent with electrostatic simulations based on local top gate geometry, a direct demonstration of local control over the band structure of graphene. This technology integrates single electron transport with high device quality and access to vibrational modes, enabling broad applications from electromechanical sensors to quantum bits.