Oxidation-assisted graphene heteroepitaxy on copper foil

TL;DR

This paper presents a novel chemical vapor deposition method that uses controlled oxidation and reduction of copper foil to produce large-area, single-crystalline graphene sheets with high quality and aligned domains.

Contribution

The study introduces an oxidation-assisted approach that improves graphene domain size and quality by controlling copper grain growth and nucleation density during synthesis.

Findings

Achieved centimeter-sized copper (111) grains via abnormal grain growth.

Produced millimeter-sized, single-crystalline graphene domains.

Demonstrated high-quality, epitaxially aligned graphene sheets.

Abstract

We propose an innovative, easy-to-implement approach to synthesize large-area singlecrystalline graphene sheets by chemical vapor deposition on copper foil. This method doubly takes advantage of residual oxygen present in the gas phase. First, by slightly oxidizing the copper surface, we induce grain boundary pinning in copper and, in consequence, the freezing of the thermal recrystallization process. Subsequent reduction of copper under hydrogen suddenly unlocks the delayed reconstruction, favoring the growth of centimeter-sized copper (111) grains through the mechanism of abnormal grain growth. Second, the oxidation of the copper surface also drastically reduces the nucleation density of graphene. This oxidation/reduction sequence leads to the synthesis of aligned millimeter-sized monolayer graphene domains in epitaxial registry with copper (111). The as-grown graphene flakes are demonstrated to be both single-crystalline and of high quality.