Spatially resolved spectroscopy of monolayer graphene on SiO2

TL;DR

This study uses scanning tunneling spectroscopy to explore how structural features like ripples and defects in monolayer graphene on SiO2 influence its local electronic properties, revealing the effects of substrate and intrinsic imperfections.

Contribution

It provides the first detailed spatially resolved analysis linking graphene's electronic inhomogeneities to ripples, defects, and substrate interactions.

Findings

Electron and hole puddles caused by ripples and impurities

Observation of short-range intervalley scattering at defects

Electronic properties are affected by substrate and intrinsic ripples

Abstract

We have carried out scanning tunneling spectroscopy measurements on exfoliated monolayer graphene on SiO$_2$ to probe the correlation between its electronic and structural properties. Maps of the local density of states are characterized by electron and hole puddles that arise due to long range intravalley scattering from intrinsic ripples in graphene and random charged impurities. At low energy, we observe short range intervalley scattering which we attribute to lattice defects. Our results demonstrate that the electronic properties of graphene are influenced by intrinsic ripples, defects and the underlying SiO$_2$ substrate.