Multilayer graphene, Moir\'e patterns, grain boundaries and defects identified by scanning tunneling microscopy on the m-plane, non-polar surface of SiC

TL;DR

This study uses atomic-scale scanning tunneling microscopy to analyze multilayer graphene on non-polar SiC surfaces, revealing Moiré patterns, grain boundaries, and defects, and correlating these features with theoretical models of membrane behavior.

Contribution

It provides new insights into the relationship between Moiré pattern wavelength and amplitude, supported by experimental observations and theoretical calculations.

Findings

Moiré patterns exhibit increasing amplitude with larger wavelength.

Multilayer graphene shows rotational disorder across the surface.

Experimental results align with theoretical predictions of membrane topography scaling.

Abstract

Epitaxial graphene is grown on a non-polar n+ 6H-SiC m-plane substrate and studied using atomic scale scanning tunneling microscopy. Multilayer graphene is found throughout the surface and exhibits rotational disorder. Moir\'e patterns of different spatial periodicities are found, and we found that as the wavelength increases, so does the amplitude of the modulations. This relationship reveals information about the interplay between the energy required to bend graphene and the interaction energy, i.e. van der Waals energy, with the graphene layer below. Our experiments are supported by theoretical calculations which predict that the membrane topographical amplitude scales with the Moir\'e pattern wavelength, L as L^-1 + \alpha L^-2.