Quantum dot behavior in graphene nanoconstrictions

TL;DR

This study investigates quantum dot behavior in graphene nanoconstrictions, revealing how device length influences quantum dot formation and transport properties, with a model explaining the role of disorder and confinement in quantum dot nucleation.

Contribution

It provides experimental evidence of quantum dot formation in graphene nanoribbons of varying lengths and proposes a model linking disorder and confinement to transport behavior.

Findings

Longer nanoribbons (>250 nm) show multiple quantum dots in series.

Shorter constrictions (≤60 nm) exhibit single or double quantum dot behavior.

Dot size correlates with constriction width.

Abstract

Graphene nanoribbons display an imperfectly understood transport gap. We measure transport through nanoribbon devices of several lengths. In nanoribbons of length greater than or equal to 250 nm we observe transport through multiple quantum dots in series, while shorter constrictions of length less than or equal to 60 nm display behavior characteristic of single and double quantum dots. Dot size scales with constriction width. We propose a model where transport occurs through quantum dots that are nucleated by background disorder potentials in the presence of a confinement gap.