Charge Detection in Graphene Quantum Dots

TL;DR

This paper demonstrates a graphene quantum dot with an integrated graphene charge detector capable of sensing individual charging events through current changes, with potential implications for quantum electronics.

Contribution

It introduces a novel graphene-based charge detection method using a nanoribbon, enabling sensitive detection of charging events in a quantum dot.

Findings

Resonances in the nanoribbon detect individual charging events.

Charging events cause 10-60% current change in the detector.

Charging energy of the quantum dot is 4.3 meV.

Abstract

We report measurements on a graphene quantum dot with an integrated graphene charge detector. The quantum dot device consists of a graphene island (diameter approx. 200 nm) connected to source and drain contacts via two narrow graphene constrictions. From Coulomb diamond measurements a charging energy of 4.3 meV is extracted. The charge detector is based on a 45 nm wide graphene nanoribbon placed approx. 60 nm from the island. We show that resonances in the nanoribbon can be used to detect individual charging events on the quantum dot. The charging induced potential change on the quantum dot causes a step-like change of the current in the charge detector. The relative change of the current ranges from 10% up to 60% for detecting individual charging events.