From One Electron to One Hole: Quasiparticle Counting in Graphene Quantum Dots Determined by Electrochemical and Plasma Etching

TL;DR

This paper demonstrates a nanometer-precision electrochemical etching method using AFM to create graphene quantum dots, enabling the identification of charge states and advancing graphene-based quantum device fabrication.

Contribution

It introduces a novel AFM-based electrochemical etching technique for fabricating graphene quantum dots with high resolution and charge state detection capabilities.

Findings

Achieved approximately 20 nm resolution in graphene quantum dot fabrication.

Identified charge neutrality point and charge states in quantum dots.

Demonstrated potential for improved lithography resolution with sharper tips.

Abstract

Graphene is considered to be a promising material for future electronics. The envisaged transistor applications often rely on precision cutting of graphene sheets with nanometer accuracy. In this letter we demonstrate graphene-based quantum dots created by using atomic force microscopy (AFM) with tip-assisted electrochemical etching. This lithography technique provides resolution of about 20 nm, which can probably be further improved by employing sharper tips and better humidity control. The behavior of our smallest dots in magnetic field has allowed us to identify the charge neutrality point and distinguish the states with one electron, no charge and one hole left inside the quantum dot.