Cobalt-assisted recrystallization and alignment of pure and doped graphene

Abstract

Recrystallization of bulk materials is a well-known phenomenon, which is widely used in commercial manufacturing. However, for low-dimensional materials like graphene, this process still remains an unresolved puzzle. Thus, the understanding of the underlying mechanisms and the required conditions for recrystallization in low dimensions is essential for the elaboration of routes towards the inexpensive and reliable production of high-quality nanomaterials. Here, we unveil the details of the efficient recrystallization of one-atom-thick pure and boron-doped polycrystalline graphene layers on a Co(0001) surface. By applying photoemission and electron diffraction, we show how more than 90% of the initially misoriented graphene grains can be reconstructed into a well-oriented and single-crystalline layer. The obtained recrystallized graphene/Co interface exhibits high structural quality with a pronounced sublattice asymmetry, which is important for achieving an unbalanced sublattice doping of graphene. By exploring the kinetics of recrystallization for native and B-doped graphene on Co, we were able to estimate the activation energy and propose a mechanism of this process.

Highly Ordered and Polycrystalline Graphene on Co(0001) Intercalated by Oxygen

“…It is known that the signal at ∼286.5−288.5 eV is related to the carbon atoms located atop Co atoms. 52 Thus, low intensity in this region and relatively narrow shape of the π* resonance β for the intercalated samples confirm a significant weakening of the interaction between the substrate and graphene. The pronounced angular dependence of π* (certain maxima are labeled as α, β, and γ) and σ* resonances indicates the preservation of the sp 2 graphene hybridization after intercalation.…”

“…One can see that the overall spectrum profiles show significant differences in the spectral structure from the case of pure graphene/Co systems. It is known that the signal at ∼286.5–288.5 eV is related to the carbon atoms located atop Co atoms . Thus, low intensity in this region and relatively narrow shape of the π* resonance β for the intercalated samples confirm a significant weakening of the interaction between the substrate and graphene.…”

Surface Engineering of Substrates for Chemical Vapor Deposition Growth of Graphene and Applications in Electronic and Spintronic Devices

“…Furthermore, Guo et al showed that the orientation of quadrilateral graphene flakes grown on Ni (110) was consistent, to some extent. 88 Most edges of the rectangular graphene domains were aligned along the [100] or [110] direction of the Ni(110) surface (Figure 6f,g). This was because that the impurity S atoms affected the Ni substrate reconstruction, which limited the growth direction of graphene domain.…”

“…Subsequently, a uniform and flat monolayer graphene film was formed on Ni(111) (Figure 6e). Furthermore, Guo et al showed that the orientation of quadrilateral graphene flakes grown on Ni (110) was consistent, to some extent. 88 Most edges of the rectangular graphene domains were aligned along the [100] or [110] direction of the Ni(110) surface (Figure 6f,g).…”

“…In 2014, a wafer-scale single-crystal monolayer graphene film was prepared on Ge single crystal by using the CVD method. 92 Owing to Ge (110) with an anisotropic 2-fold symmetry, graphene islands grew on its surface along the [−110] direction (Figure 7a) and finally formed a wafer-size integrated monolayer film by seamless stitching. The Ge surface could absorb H atoms at high temperature and thus the interaction between graphene and Ge was weakened, which was conducive to the formation of flat graphene surface and transferring graphene to other substrates.…”