Growth and Characterization of Graphene Layers on Different Kinds of Copper Surfaces

Peter M Rafailov,Boyko Katranchev,Haritun Naradikian,Ivalina Avramova,Stefan I Boyadjiev,Peter K Sveshtarov,Penka Terziyska,Imre M Szilágyi,Zoltán Erdélyi,Csaba Cserháti,Minko Petrov,Vladimir B Mehandzhiev

doi:10.3390/molecules27061789

Abstract

Graphene films were grown by chemical vapor deposition on Cu foil. The obtained samples were characterized by Raman spectroscopy, ellipsometry, X-ray photoelectron spectroscopy and electron back-scatter diffraction. We discuss the time-dependent changes in the samples, estimate the thickness of emerging Cu2O beneath the graphene and check the orientation-dependent affinity to oxidation of distinct Cu grains, which also governs the manner in which the initial strong Cu-graphene coupling and strain in the graphene lattice is released. Effects of electropolishing on the quality and the Raman response of the grown graphene layers are studied by microtexture polarization analysis. The obtained data are compared with the Raman signal of graphene after transfer on glass substrate revealing the complex interaction of graphene with the Cu substrate.

Highlights

Since its discovery, graphene has been viewed as promising candidate for novel optoelectronic devices due to its extraordinary ballistic transport over micron lengths and large carrier mobility [1–3] combined with over 97% transparency for visible light [4]
In view of the growing interest in graphene, practical experience has established chemical vapor deposition (CVD) as the most prospective and readily accessible synthesis approach to satisfy the complex requirements of opto- and microelectronics for large-area and highquality graphene with low density of structural defects [5]
It has been found that Cu (111) surfaces grow the highest quality monolayer graphene while graphene grown on other low-index surfaces occasionally exhibits a multilayered structure and more defects [9]

Summary

Introduction

Graphene has been viewed as promising candidate for novel optoelectronic devices due to its extraordinary ballistic transport over micron lengths and large carrier mobility [1–3] combined with over 97% transparency for visible light [4]. Raman spectroscopy is a preferred characterization method for the study of graphene and the novel graphene-like 2D materials, as it is nondestructive, achieves high resolution with relatively simple commercially available setups and provides valuable information on the defect density, number of layers and their mechanical state Most importantly, this technique reveals details of the electronic structure via the electron–phonon coupling and the rich single- and double-resonance phenomena characteristic for the Raman response of carbon-based materials. We study how Cu-graphene coupling is affected by oxygen penetration and copper surface oxidation on various time scales For this purpose, we apply a combined approach including Raman and X-ray photoelectron spectroscopy (XPS), ellipsometry and electron back-scatter diffraction (EBSD). Primarily applied for studying of liquid crystal properties, this method is very useful in the present case because the grain boundaries of the graphene domains become observable simultaneously with those of the copper grains

Materials and Methods

Sample Characterization with Raman and X-ray Photoelectron Spectroscopy

Study of the