Synthesis of Single-Crystal Graphene on Copper Foils Using a Low-Nucleation-Density Region in a Quartz Boat.

Kaiqiang Yang,Feng Chi,Baoqing Zeng,Yubin Gong,Qingguo Gao,Ruirui Jiang,Liming Liu,Zichuan Yi,Jianjun Yang,Jianlong Liu

doi:10.3390/mi12101236

Kaiqiang Yang, Feng Chi + Show 8 more

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https://doi.org/10.3390/mi12101236

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Abstract

The nucleation of graphene at different locations in the quartz boat was studied, and the lowest nucleation density of graphene in the quartz boat was found. The nucleation density of graphene is the lowest at the bottom of the quartz boat near the gas inlet side. Based on the above results, a simple and reproducible way is proposed to significantly suppress the nucleation density of graphene on the copper foil during the chemical vapor deposition process. Placing the copper foil with an area of 1.3 cm × 1 cm in the middle of the bottom of the quartz boat or further back, and placing two copper pockets in front of the copper foil, an ultra-low nucleation density of ~42 nucleus/cm2 was achieved on the back of the copper foil. Single-crystal monolayer graphene with a lateral size of 800 μm can be grown on the back of copper foils after 60 min of growth. Raman spectroscopy revealed the single-crystal graphene to be in uniform monolayers with a low D-band intensity.

Highlights

Single-crystal graphene grains could be observed under the microscope
We found that the nucleation density of graphene on the bottom of the quartz boat near the gas inlet side was lower than that in the top of the quartz boat near the gas outlet side with the copper pockets method
We found that as long as the copper foils that were cut to about 1 cm2 were placed at the bottom of quartz boat, and two copper pockets were in front of this, single-crystal graphene could be stably obtained on the surfaces of copper foils

Summary

Introduction

Academic Editor: Ha Duong Ngo. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Graphene is composed of two-dimensional carbon atoms assembled in a hexagonal structure, akin to a honeycomb, and has exceptional chemical stability, superior mechanical stability, and very high thermal conductivities and electronic conductivities [1,2,3]. Because of the above excellent properties, graphene has potential applications in ultra-high-speed electronics [4], flexible transparent conductive films [5,6], solar cells [6], separation membranes [7], and transmission electron microscopy (TEM) imaging [8]. Graphene was first isolated by mechanical exfoliation from Highly Oriented Pyrolytic Graphite (HOPG) [1]

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