Native defects in ultra-high vacuum grown graphene islands on Cu(111)

TL;DR

This study uses STM to analyze native defects in UHV-grown graphene on Cu(111), identifying their types, imaging conditions, and effects on local electronic properties.

Contribution

It provides detailed characterization of native defects in graphene on Cu(111), including their identification, imaging conditions, and electronic impact, using STM techniques.

Findings

Bright defects are likely single C vacancies.

Dark defects are likely Cu surface point defects.

Defects influence local electronic properties of graphene.

Abstract

We present a scanning tunneling microscopy (STM) study of native defects in graphene islands grown by ultra-high vacuum (UHV) decomposition of ethylene on Cu(111). We characterize these defects through a survey of their apparent heights, atomic-resolution imaging, and detailed tunneling spectroscopy. Bright defects that occur only in graphene regions are identified as C site point defects in the graphene lattice and are most likely single C vacancies. Dark defect types are observed in both graphene and Cu regions, and are likely point defects in the Cu surface. We also present data showing the importance of bias and tip termination to the appearance of the defects in STM images and the ability to achieve atomic resolution. Finally, we present tunneling spectroscopy measurements probing the influence of point defects on the local electronic landscape of graphene islands.