Epitaxial graphene morphologies probed by weak (anti)-localization

TL;DR

This paper demonstrates how weak magneto-conductance measurements can characterize epitaxial graphene morphologies and distinguish between mono-layer and bilayer structures based on quantum interference effects.

Contribution

It introduces a method using weak (anti-)localization to analyze epitaxial graphene grown on different SiC faces, linking morphology to electronic properties.

Findings

Anti-localization and localization depend on growth conditions.

Diffusion lengths match STM and theoretical models.

Method distinguishes mono-layer and bilayer graphene.

Abstract

We show how the weak field magneto-conductance can be used as a tool to characterize epitaxial graphene samples grown from the C or the Si face of Silicon Carbide, with mobilities ranging from 120 to 12000 cm^2/(V.s). Depending on the growth conditions, we observe anti-localization and/or localization which can be understood in term of weak-localization related to quantum interferences. The inferred characteristic diffusion lengths are in agreement with the scanning tunneling microscopy and the theoretical model which describe the "pure" mono-layer and bilayer of graphene [MacCann et al,. Phys. Rev. Lett. 97, 146805 (2006)].