Hexagonal Single Crystal Domains of Few-Layer Graphene on Copper Foils

Abstract

Hexagonal-shaped single crystal domains of few layer graphene (FLG) are synthesized on copper foils using atmospheric pressure chemical vapor deposition with a high methane flow. Scanning electron microscopy reveals that the graphene domains have a hexagonal shape and are randomly orientated on the copper foil. However, the sites of graphene nucleation exhibit some correlation by forming linear rows. Transmission electron microscopy is used to examine the folded edges of individual domains and reveals they are few-layer graphene consisting of approximately 5-10 layers in the central region and thinning out toward the edges of the domain. Selected area electron diffraction of individual isolated domains reveals they are single crystals with AB Bernal stacking and free from the intrinsic rotational stacking faults that are associated with turbostratic graphite. We study the time-dependent growth dynamics of the domains and show that the final continuous FLG film is polycrystalline, consisting of randomly connected single crystal domains.

Step driven competitive epitaxial and self-limited growth of graphene on copper surface

“…3(b)). This is consistent with a previous study, 18 where graphene was found to preferentially nucleate along linear axes due to the initial nucleation occurring at step edges, pinning sites, or other imperfections that are linear in character. Our observations suggest that the step edge serves as carbon adatom (or cluster) sink to promote a step-flow type of growth.…”

“…1(d) (except for the "suspended" graphene film), randomly distributed graphene domains (dark regions) can be identified beneath the top layer in a typical atmospheric pressure CVD grown sample. The top-layer graphene film is a product of the self-limited process 8 ; while the underlying domains come from the epitaxial growth mode and correspond to a multilayered structure 17,18 (see Raman spectra in Fig. 1(e)).…”

“…15,17,18 The self-limited process is surface mediated and generally used to grow monolayer graphene, regardless of the crystallographic orientation of the copper surface. 8 Epitaxial growth can occur more readily on Cu(111) due to the easy lattice matching between graphene and copper, 15 or on an already grown graphene domain that acts as an epitaxial template 17,18 for the formation of multilayer graphene. In both cases, the presence of step edges or impurity elements and their states on surfaces will strongly influence the graphene nucleation and subsequent growth.…”

Chemical vapour deposition growth of large single crystals of monolayer and bilayer graphene

“…5a). A typical spectrum (red colour spectrum) shows a wider and asymmetric 2D band (full width at half-maximum of 58 cm À 1 ) with the 2D/G intensity ratio of about 0.8, which is quite similar to that of the exfoliated bilayer graphene samples with AB-stacking order [36][37][38] .…”

Flexible Supercapacitors – Development of Bendable Carbon Architectures

“…[55] Its unique structure and properties make graphene promising for a EDLC electrodes. [56] Although pure graphene sheets with high quality can be prepared by mechanical cleavage of graphite [57] or CVD method at high temperature, [58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76] these methods suffer from high cost, high temperature, substrate limitation, and extremely low yield. In addition, the surface of pristine graphene is so hydrophobic that pristine graphene tend to agglomerate in solvents, leading to the loss of excellent properties of monolayer graphene sheets.…”