Networks of ABA and ABC stacked graphene on mica observed by scanning tunneling microscopy

TL;DR

This study uses scanning tunneling microscopy to observe and analyze the stacking order and electronic properties of graphene flakes on mica, revealing distinct structural and electronic features of ABA and ABC stacking configurations.

Contribution

It provides detailed STM imaging and spectroscopy of ABA and ABC stacked graphene on mica, highlighting their structural differences and electronic signatures.

Findings

Triangular network of partial dislocations separates ABA and ABC stacking.

Distinct electronic peak at 0.25 eV in ABA-stacked regions.

Differences in apparent height in STM images due to electronic structure.

Abstract

Graphene flakes are prepared on freshly cleaved mica by exfoliation and studied by scanning tunneling microscopy in ultra high vacuum. On few-layer graphene, a triangular network of partial dislocations separating ABC stacked and ABA stacked graphene was found similar to the networks occasionally visible on freshly cleaved HOPG. We found differences in the electronic structure of ABC and ABA stacked areas by scanning tunneling spectroscopy, i.e., a pronounced peak at 0.25 eV above the Fermi level exclusively in the ABA areas, which is shown to be responsible for the different apparent heights observed in STM images.