Influence of Different Copper Treatment on the Formation of Single-Layer Graphene by CVD Method

Ivan Kondrashov,Pavel Pivovarov,Maxim Komlenok,Elena Obraztsova,Maxim Rybin,Sergei Savin

doi:10.3390/iocn2020-07839

Abstract

Chemical vapor deposition synthesis of graphene on copper foil from methane is the most promising technology for industrial production. However, an important problem of the formation of the second and subsequent graphene layers during synthesis arises due to the strong roughness of the initial copper foil. Here we demonstrate the various approaches to prepare a smooth copper surface before graphene synthesis to reduce the formation of multi-layer graphene islands. Six methods of surface processing of copper foils are studied, and the decrease of the roughness from 250 to as low as 80 nm is achieved. The correlation between roughness and the formation of multi-layer graphene is demonstrated. Under optimized conditions of surface treatment, the content of the multi-layer graphene islands drops from 9% to 2.1%. The quality and the number of layers of synthesized graphene are analyzed by Raman spectroscopy, scanning electron microscopy, and measurements of charge mobility.

Highlights

Chemical vapor deposition (CVD) synthesis of graphene on metal substrates is the most promising method for growing large-area films of high-quality [1]
The chemical vapor deposition technique is an efficient approach for the synthesis of high-quality graphene on copper foil over large areas
The roughness of the copper surface is the key parameter for the fabrication of the most uniform single-layer graphene film

Summary

Introduction

Chemical vapor deposition (CVD) synthesis of graphene on metal substrates is the most promising method for growing large-area films of high-quality [1]. If the copper surface is well developed and has a strong roughness, the formation of a second graphene layer during synthesis becomes more likely than on a smooth surface. One of the most efficient ways to grow an ideal graphene monolayer is to use a smooth single-crystal copper [5]. A simpler and more affordable option to reduce the formation of the second graphene layer is to process the surface of copper before the synthesis to reduce surface roughness. The annealing (resolidification) is a relatively simple method for smoothing the surface of copper It is based on a rearrangement of surface copper atoms, which leads to the release of internal stresses and an increase in crystal size

Methods

Results

Conclusion