Selecting a single orientation for millimeter sized graphene sheets

TL;DR

This study demonstrates methods to produce large-area, single-orientation graphene sheets on Ir(111) using CVD, cyclic growth, and substrate precoverage, enabling high-quality graphene for advanced applications.

Contribution

The paper introduces a novel approach combining cyclic growth and substrate precoverage to achieve millimeter-scale, single-orientation graphene films with high purity.

Findings

CVD at high temperature produces uniform monatomic graphene sheets.

Cyclic growth enhances alignment, reaching 99% aligned domains.

Precovering substrate with nuclei yields millimeter-scale aligned graphene films.

Abstract

We have used Low Energy Electron Microscopy (LEEM) and Photo Emission Electron Microscopy (PEEM) to study and improve the quality of graphene films grown on Ir(111) using chemical vapor deposition (CVD). CVD at elevated temperature already yields graphene sheets that are uniform and of monatomic thickness. Besides domains that are aligned with respect to the substrate, other rotational variants grow. Cyclic growth exploiting the faster growth and etch rates of the rotational variants, yields films that are 99 % composed of aligned domains. Precovering the substrate with a high density of graphene nuclei prior to CVD yields pure films of aligned domains extending over millimeters. Such films can be used to prepare cluster-graphene hybrid materials for catalysis or nanomagnetism and can potentially be combined with lift-off techniques to yield high-quality, graphene based electronic devices.