Epitaxial Graphene Nanoribbons on Bunched Steps of a 6H-SiC(0001) Substrate: Aromatic Ring Pattern and Van Hove Singularities

TL;DR

This study uses scanning tunneling microscopy and spectroscopy to analyze epitaxial graphene nanoribbons on 6H-SiC(0001), revealing aromatic ring patterns and Van Hove singularities indicative of one-dimensional electronic properties.

Contribution

It demonstrates the atomic structure and electronic features of graphene nanoribbons grown on SiC steps, supported by experimental imaging and density functional theory simulations.

Findings

Aromatic ring pattern (sqrt(3)x sqrt(3))R30{ extdegree} observed on nanoribbons.

Presence of sharp Van Hove singularities in spectroscopy spectra.

Agreement between experimental images and theoretical simulations.

Abstract

We report scanning tunneling microscopy and spectroscopy investigation of graphene nanoribbons grown on an array of bunched steps of a 6H-SiC(0001) substrate. Our scanning tunneling microscopy images of a graphene nanoribbons on a step terrace feature a (sqrt(3)x sqrt(3))R30{\deg} pattern of aromatic rings which define our armchair nanoribbons. This is in agreement to a simulation based on density functional theory. As another signature of the one-dimensional electronic structure, in the corresponding scanning tunneling spectroscopy spectra we find well developed, sharp Van Hove singularities.