Fabrication and Study of Large Area QHE Devices Based on Epitaxial Graphene

TL;DR

This study reports the fabrication and characterization of large-area epitaxial graphene quantum Hall effect devices on SiC, demonstrating their potential for resistance standards with high precision at moderate magnetic fields.

Contribution

The paper introduces a double metalization process for improved contacts and a photochemical gating method for tuning carrier density in epitaxial graphene QHE devices.

Findings

Quantum Hall effect observed at 3 T magnetic field.

Achieved relative agreement within 6×10^-9 in resistance measurements.

Enhanced device fabrication techniques for precision quantum Hall devices.

Abstract

Quantum Hall effect (QHE) devices based on epitaxial graphene films grown on SiC were fabricated and studied for development of the QHE resistance standard. The graphene-metal contacting area in the Hall devices has been improved and fabricated using a double metalization process. The tested devices had an initial carrier concentration of (0.6 - 10)*10^11 1/cm^2 and showed half-integer quantum Hall effect at a relatively low (3 T) magnetic field. Application of the photochemical gating method and annealing of the sample provides a convenient way for tuning the carrier density to the optimum value. Precision measurements of the quantum Hall resistance (QHR) in graphene and GaAs devices at moderate magnetic field strengths (<7 T) showed a relative agreement within 6*10^-9.