Rotational stacking and its electronic effects on graphene films grown on 4H-SiC$(000\bar{1})$

TL;DR

This study investigates the stacking order of multilayer graphene on SiC, revealing rotational faults that electronically decouple layers, preserving Dirac cone features similar to single-layer graphene.

Contribution

It demonstrates that rotational stacking faults in multilayer graphene on SiC lead to electronic decoupling, maintaining single-layer-like electronic properties.

Findings

Rotational stacking faults are prevalent in graphene on SiC.

Rotated graphene layers exhibit Dirac cones similar to single-layer graphene.

Ab initio calculations confirm electronic decoupling at fault boundaries.

Abstract

We examine the stacking order of multilayer graphene grown on the SiC$(000\bar{1})$ surface using low-energy electron diffraction and surface X-ray diffraction. We show that the films contain a high density of rotational stacking faults caused by three types of rotated graphene: sheets rotated $30^\circ$ and $\pm 2.20^\circ$ relative to the SiC substrate. These angles are unique because they correspond to commensurate phases of layered graphene, both with itself and with the SiC substrate. {\it Ab intio} calculations show that these rotational phases electronically decouple adjacent graphene layers. The band structure from graphene at fault boundaries displays linear energy dispersion at the $K$-point (Dirac cones), nearly identical to that of a single graphene sheet.