Roles of Oxygen and Hydrogen in Crystal Orientation Transition of Copper Foils for High-Quality Graphene Growth

Abstract

The high-quality graphene film can be grown on single-crystal Cu substrate by seamlessly stitching the aligned graphene domains. The roles of O2 and H2 have been intensively studied in the graphene growth kinetics, including lowering the nucleation sites and tailoring the domain structures. However, how the O2 and H2 influence Cu orientations during recrystallization prior to growing graphene, still remains unclear. Here we report that the oxidation of Cu surface tends to stabilize the Cu(001) orientation while impedes the evolution of Cu(111) single domain during annealing process. The crystal orientation-controlled synthesis of aligned graphene seeds is further realized on the long-range ordered Cu(111) substrate. With decreasing the thickness of oxide layer on Cu surface by introducing H2, the Cu(001) orientation changes into Cu(111) orientation. Meanwhile, the average domain size of Cu foils is increased from 50 μm to larger than 1000 μm. The density functional theory calculations reveal that the oxygen increases the energy barrier for Cu(111) surface and makes O/Cu(001) more stable than O/Cu(111) structure. Our work can be helpful for revealing the roles of O2 and H2 in controlling the formation of Cu single-crystal substrate as well as in growing high-quality graphene films.

Oxide-assisted growth of scalable single-crystalline graphene with seamlessly stitched millimeter-sized domains on commercial copper foils

“…19 Herein, we demonstrated a new pathway for the growth of scalable monolayer single-crystalline graphene by seamlessly stitching the unidirectionally aligned arrays of millimeter-sized hexagonal domains using different types of commercially available Cu foils and industrially safe atmospheric pressure conditions. Compared with that reported in similar previous studies, [13][14][15][16][17][18][19] the average size for the hexagonal graphene domains is enlarged by 1-2 orders of magnitude (from tens of micrometers to millimeter); this further eliminates the formation of domain boundaries. The key factor that leads to the success of this growth is the monocrystallization of the catalytic Cu surface to centimeter-sized (111) textures by simply preintroducing a Cu oxide layer for high-temperature surface reconstruction.…”

“…However, the attempts based on this approach are oen frustrated by the complication and cost of the Cu surface treatments such as tenuous polishing and/or elongated annealing, tightly rolled Cu foils into a cylinder, etc. [13][14][15][16][17][18] In a recent study reported by Xu et al, the epitaxial growth of meter-sized single-crystal graphene was realized, but a relatively complex experimental setup with small constituent domain sizes (<100 mm) was used, making the probability of the coalesced domain boundaries not negligible even with a 99% unidirectional orientation. 19 Herein, we demonstrated a new pathway for the growth of scalable monolayer single-crystalline graphene by seamlessly stitching the unidirectionally aligned arrays of millimeter-sized hexagonal domains using different types of commercially available Cu foils and industrially safe atmospheric pressure conditions.…”

Basic Concepts and Recent Advances of Crystallographic Orientation Determination of Graphene by Raman Spectroscopy

“…[55][56][57] The D peak dispersion at the edge is ∼50 cm -1 / eV, similar to the D peak inside graphite. 41,[58][59][60] That of the 2D and 2D′ peaks is ∼95 and ∼21 cm -1 /eV, respectively, as in refs 17 and 61. Figure 8A plots the spectra for different incident polarization.…”

“…Scanning electron microscopy [39,41] was also employed to characterize crystallographic orientation of graphene. Orientation can be characterized from graphene outlines.…”

“…Up to now, various techniques have been developed to determine the crystallographic orientation of graphene, such as transmission electron microscopy [37][38][39] and selected-area electron diffraction [39,40], scanning electron microscopy [39,41], anisotropic optical absorption [42], high-resolution scanning tunneling microscopy [43][44][45], and so on. Among these techniques, Raman spectroscopy is a nondestructive, fast, and powerful technique to collect structural and electronic information of graphene.…”