Graphene quantum blisters: a tunable system to confine charge carriers

TL;DR

This paper introduces a novel method for electrostatically confining charge carriers in bilayer graphene using quantum blisters, enabling tunable bound states despite Klein tunneling limitations.

Contribution

It proposes a new system of graphene quantum blisters with decoupled layers for tunable charge confinement, overcoming previous confinement challenges in graphene.

Findings

Bound states are generated in bilayer graphene with quantum blisters.

Energy levels are tunable via a global electrostatic gate.

States near the continuum are mainly outside the blister region.

Abstract

Due to Klein tunneling, electrostatic confinement of electrons in graphene is not possible. This hinders the use of graphene for quantum dot applications. Only through quasi-bound states with finite lifetime has one achieved to confine charge carriers. Here we propose that bilayer graphene with a local region of decoupled graphene layers is able to generate bound states under the application of an electrostatic gate. The discrete energy levels in such a quantum blister correspond to localized electron and hole states in the top and bottom layers. We find that this layer localization and the energy spectrum itself are tunable by a global electrostatic gate and that the latter also coincides with the electronic modes in a graphene disk. Curiously, states with energy close to the continuum exist primarily in the classically forbidden region outside the domain defining the blister. The results are robust against variations in size and shape of the blister which shows that it is a versatile system to achieve tunable electrostatic confinement in graphene.