Single-Layer Graphene Synthesis on a Al₂O₃(0001)/Cu(111) Template Using Chemical Vapor Deposition

Abstract

The parameter space of graphene growth using chemical vapor deposition on an untwinned single-crystalline Al 2 O 3 (0001)/Cu(111) template is discussed. The influence of growth temperature, methane flow and carbon dose is examined to assess graphene quality and multilayer coverage. An optimized growth window is identified yielding single-layer graphene. Production temperatures above 850 • C result in a graphene quality improvement, but also an increase in multilayer coverage. Adapting graphene dosages by minimizing the growth time is the key element to reduce the amount of multilayer domains without affecting the quality. After graphene transfer, the multilayer graphene areas show a large increase in I 2D /I G peak ratio, which indicates a turbostratic stacking order of graphene multilayer domains. Two growth models are put forward, i.e. a carbon penetration mechanism and an adsorption-diffusion mechanism.

Graphene Growth on Electroformed Copper Substrates by Atmospheric Pressure CVD

“…In fact, the 2D band FWHM is close to the value measured on Si/SiO 2 for graphene obtained by mechanical cleavage of graphite [19]. Moreover, the I 2D /I G ratio was high enough to confirm the presence of a single monolayer [35]. The I D /I G ratio was higher with this sample, suggesting that small domains exist in monolayer graphene, associated with relatively high nucleation density.…”

“…Multilayer islands probably formed by nucleation and growth of new layers next to the substrate [34]. Diffusion of C adatoms under the graphene sheets is permitted by the weak interaction between graphene and Cu substrate and is favored when C adsorption at graphene edges is hindered [34]; this typically occurs when edge sites are terminated by hydrogen in CVD atmospheres with high partial pressure of hydrogen [35], similar to that used in the present work.…”

Breakdown of Universal Scaling for Nanometer-Sized Bubbles in Graphene

“…Our samples consist of epitaxial graphene grown by chemical vapor deposition (CVD) on epitaxial Pt(111) and Cu(111) thin films grown on sapphire(0001) substrates. , Nanobubbles are formed by implanting noble gas ions (He, Ne, and Ar), with a kinetic energy of 25 eV, with perpendicular incidence with respect to the surface. Bubbles were found to only form for graphene on Pt(111) (Figure ), not for graphene on Cu(111) (Figure S1).…”

Thermal Annealing of Graphene Implanted with Mn at Ultralow Energies: From Disordered and Contaminated to Nearly Pristine Graphene

“…The pointlike depressions (some of them indicated by the white arrows) have been related to contaminants such as CO − and O; we will refer to them hereafter as Cu defects. The nanometer scale patch indicated by the orange arrow is associated with Cu oxide which can vary from one sample to another, and it is in the range of a few percent coverage of the surface . In the as-implanted state, one main additional type of defect appears that is characterized by a nanometer scale circular patch where the atomic lattice of graphene is more easily resolved (some of them indicated by red arrows in Figure b).…”

“…Our samples consist of epitaxial graphene grown by chemical vapor deposition (CVD) on epitaxial Cu(111) thin films grown on sapphire(0001) substrates; the graphene layer covers the full surface of the Cu/sapphire film . Two inch polished Czochralski grown sapphire wafers cut along the c -plane with <0.1° miscut were used to prepare Al 2 O 3 template wafers.…”