Correlating Raman Spectral Signatures with Carrier Mobility in Epitaxial Graphene: A Guide to Achieving High Mobility on the Wafer Scale

TL;DR

This study establishes a direct link between Raman spectral features and carrier mobility in epitaxial graphene, highlighting the importance of uniform thickness, strain, and stacking for achieving ultra-high mobility on wafer-scale substrates.

Contribution

It provides a practical guide to correlate Raman signatures with carrier mobility, enabling rapid assessment and optimization of epitaxial graphene growth for high-performance electronic applications.

Findings

Carrier mobility exceeds 1000 cm2/V-s when thickness and strain are uniform over >40% of the area.

High mobility of 18,100 cm2/V-s achieved on C-face SiC.

Ultra-high mobilities (>50,000 cm2/V-s) are possible with controlled rotational stacking.

Abstract

We report a direct correlation between carrier mobility and Raman topography of epitaxial graphene (EG) grown on silicon carbide (SiC). We show the Hall mobility of material on the Si-face of SiC [SiC(0001)] is not only highly dependent on thickness uniformity but also on monolayer strain uniformity. Only when both thickness and strain are uniform over a significant fraction (> 40%) of the device active area does the mobility exceed 1000 cm2/V-s. Additionally, we achieve high mobility epitaxial graphene (18,100 cm2/V-s at room temperature) on the C-face of SiC [SiC(000-1)] and show that carrier mobility depends strongly on the graphene layer stacking. These findings provide a means to rapidly estimate carrier mobility and provide a guide to achieve very high mobility in epitaxial graphene. Our results suggest that ultra-high mobilities (>50,000 cm2/V-s) are achievable via the controlled formation of uniform, rotationally faulted epitaxial graphene.