| The field of graphene and carbon nanotube (CNT) growth is in its infancy and studies elucidating the role of various process parameters and synthesis mechanisms in novel, unexplored growth regimes are strongly desired. Chemical vapor deposition (CVD) is a simple, low-cost technique for synthesizing high-yield, high purity graphene and CNTs. CVD control is versatile in that growth can be accomplished on various substrates and in a variety of architectures and alignments if the fundamental process mechanisms are understood.;This work first explores the effect of growth kinetics and Cu catalytic activity on thickness, continuity, and defect density of CVD graphene. Monolayer graphene growth is substantiated under mass transport and surface reaction regimes in excellent agreement with kinetic theory. Extrinsic factors arising from post-growth processing are systematically eliminated to reduce mechanical defects and residual metal dopants. The impact of polymer removal by forming gas and vacuum annealing on the doping, strain, and morphology of CVD and mechanically exfoliated graphene is investigated. The well-known doping effect from gas annealing, which degrades graphene electrical performance, is found to be partially irreversible and caused by a combination of hydrogen functionalization and polymeric residue. For the first time, the processes which cause doping and strain level shifts, such as interfacial water removal, increased corrugation of graphene, incomplete removal of polymer and graphene deformation, are fully illustrated.;Next, a novel anisotropic graphene growth mode is studied at atmospheric pressure and is found to be dependent on the underlying Cu orientation, giving rise to a two-lobed curvilinear graphene domain. The symmetry of this domain is dependent on carbon adatom surface diffusion along the Cu and directions and the shape of the lobes is influenced by an angularly dependent growth rate owing to surface energy anisotropy on Cu{100}. This rate is lower than the well-known isotropic growth on higher index Cu facets, indicating the need for precise control of Cu crystal orientation for uniform graphene growth.;Finally, an approach is demonstrated towards controlled CVD growth of CNTs atop large-area monolayer graphene substrates. A method is presented to suppress catalytic hydrogenation, and thus, reduce etching of graphene during out-of-plane CNT growth. This is a key finding towards development of graphene-CNT 3-D architectures where the continuity and integrity of the materials is preserved. |
