Elementary Process for CVD Graphene on Cu(110): Size-selective Carbon Clusters

Jialin Zhang,Shengnan Wang,Zhunzhun Wang,Tianchao Niu,Zhenyu Li,Wei Chen

doi:10.1038/srep04431

Abstract

Revealing the graphene growth mechanism at the atomic-scale is of great importance for achieving high quality graphene. However, the lack of direct experimental observation and density functional theory (DFT) verification hinders a comprehensive understanding of the structure of the carbon clusters and evolution of the graphene growth on surface. Here, we report an in-situ low-temperature scanning tunneling microscopy (LT-STM) study of the elementary process of chemical vapor deposition (CVD) graphene growth via thermal decomposition of methane on Cu(110), including the formation of monodispersed carbon clusters at the initial stage, the graphene nucleation and the ripening of graphene islands to form continuous graphene film. STM measurement, supported by DFT calculations, suggests that the carbon clusters on the surface are C2H5. It is found that graphene layers can be joined by different domains, with a relative misorientation of 30°. These graphene layers can be decoupled from Cu(110) through low temperature thermal cycling.

Highlights

Revealing the graphene growth mechanism at the atomic-scale is of great importance for achieving high quality graphene
The graphene growth on transition metal (TM) surfaces is based on high-temperature pyrolysis of hydrocarbons and different growth mechanisms can be involved according to the carbon solubility limit in the metal
The growth of graphene can be accomplished by chemical vapor deposition (CVD) via two approaches: directly cracking the carbon source on TM surface at a high temperature or temperature programmed growth (TPG) via room temperature adsorption of the molecules followed by pyrolysis and graphene growth at a fixed elevated temperature[17]

Summary

Introduction

Revealing the graphene growth mechanism at the atomic-scale is of great importance for achieving high quality graphene. Very little of the growth mechanism in the initial nucleation stages of carbon atoms has been revealed experimentally[15,16,44] In this regard, atomic-scale characterization of a complete process of graphene growth in combination with theoretical calculations is of great importance, for both fundamental interest and achieving high quality graphene. We report an atomic scale characterization of the elementary process of CVD graphene growth via thermal decomposition of methane (CH4) on Cu(110) using low-temperature scanning tunneling microscopy (LT-STM), including the formation of monodispersed carbon clusters at low temperature, nucleation and ripening of graphene islands at high temperature. These graphene layers can be decoupled from Cu(110) through low temperature thermal cycling

Methods

Results

Conclusion