Epitaxial graphene homogeneity and quantum Hall effect in millimeter-scale devices

TL;DR

This study demonstrates high-quality, large-area epitaxial graphene with uniform properties exhibiting the quantum Hall effect at millimeter scales, promising for advanced electronic applications.

Contribution

It provides detailed characterization and confirms the homogeneity of epitaxial graphene over millimeter scales, enabling reliable quantum Hall effect in large devices.

Findings

Quantized Hall resistance maintained up to high current levels

Low and homogeneous strain observed via Raman microscopy

High mobility measured near the Dirac point

Abstract

Quantized magnetotransport is observed in 5.6 x 5.6 mm^2 epitaxial graphene devices, grown using highly constrained sublimation on the Si-face of SiC(0001) at high temperature (1900 {\deg}C). The precise quantized Hall resistance of Rxy = h/2e^2 is maintained up to record level of critical current Ixx = 0.72 mA at T = 3.1 K and 9 T in a device where Raman microscopy reveals low and homogeneous strain. Adsorption-induced molecular doping in a second device reduced the carrier concentration close to the Dirac point(n ~ 1E10 (1/cm^2)), where mobility of 43700 cm^2/Vs is measured over an area of 10 mm^2. Atomic force, confocal optical, and Raman microscopies are used to characterize the large-scale devices, and reveal improved SiC terrace topography and the structure of the graphene layer. Our results show that the structural uniformity of epitaxial graphene produced by face-to-graphite processing contributes to millimeter-scale transport homogeneity, and will prove useful for scientific and commercial applications.