Indirect measurement of the carbon adatom migration barrier on graphene

TL;DR

This study estimates the carbon adatom migration barrier on graphene by analyzing temperature-dependent electron damage rates, providing a novel indirect measurement method for surface diffusion barriers.

Contribution

It introduces an indirect approach to measure adatom migration barriers on graphene using damage rate analysis, which is challenging to study directly.

Findings

Migration barrier of (0.33 ± 0.03) eV determined

Damage rate decreases with increasing temperature

Method applicable to other surface diffusion studies

Abstract

Although surface diffusion is critical for many physical and chemical processes, including the epitaxial growth of crystals and heterogeneous catalysis, it is particularly challenging to directly study. Here, we estimate the carbon adatom migration barrier on freestanding monolayer graphene by quantifying its temperature-dependent electron knock-on damage. Due to the fast healing of vacancies by diffusing adatoms, the damage rate decreases with increasing temperature. By analyzing the observed damage rates at 300-1073 K using a model describing our finite scanning probe, we find a barrier of (0.33 \pm 0.03) eV.