Tunable Graphene Single Electron Transistor

TL;DR

This paper presents experiments on a graphene single electron transistor with tunable electrostatic properties, revealing localized states and energy scales relevant for quantum transport.

Contribution

It demonstrates a graphene-based single electron transistor with electrostatic tunability and detailed energy scale analysis, advancing graphene quantum device research.

Findings

Charging energy of 3.4 meV from Coulomb diamonds

Characteristic energy scale for constriction resonances of 10 meV

Presence of localized states affecting tunneling coupling

Abstract

We report electronic transport experiments on a graphene single electron transistor. The device consists of a graphene island connected to source and drain electrodes via two narrow graphene constrictions. It is electrostatically tunable by three lateral graphene gates and an additional back gate. The tunneling coupling is a strongly nonmonotonic function of gate voltage indicating the presence of localized states in the barriers. We investigate energy scales for the tunneling gap, the resonances in the constrictions and for the Coulomb blockade resonances. From Coulomb diamond measurements in different device configurations (i.e. barrier configurations) we extract a charging energy of 3.4 meV and estimate a characteristic energy scale for the constriction resonances of 10 meV.