Abstract
Graphene is a two dimensional material which attracted a lot of attention in materials science and condensed-matter physic. Chemical vapor deposition (CVD) is the most promising, inexpensive, large-area and readily accessible approach for high quality graphene. However, the growth mechanism between graphene and the substrate is still not well understood. Therefore, we studied two growth conditions for graphene by using copper as substrate, one was graphene grown on melting copper substrate, and the other was solid state copper substrate. In the first part of the thesis, we synthesized graphene on the melting catalyst by using copper foil as substrate in high temperature process. On the other hand, we combine electron backscatter diffraction (EBSD) and Raman mapping as non-destructive characterization techniques to locally probe the interface between graphene and copper foils lattice without removing the graphene. We observed that the crystal structure of the Cu grains under graphene layers is governed by two competing processes: (1) graphene induced Cu surface reconstruction favoring the formation of Cu(100) orientation, and (2) recrystallization from bulk Cu favoring Cu(111) formation. The strong interaction between graphene and Cu could be decoupled by allowing the intercalation of a thin cuprous oxide interfacial-layer. The Cu2O layer is mechanically and chemically weak; hence, graphene films can be detached and transferred to arbitrary substrates and the Cu substrates may be re-used for graphene growth. Secondly, we successfully synthesized a high-quality and wafer scale graphene thin layers on insulating gate dielectrics and studied the graphene growth condition on solid catalyst by using Cu thin film on dielectric substrate. In this work, we report that carbon species dissociated on Cu surfaces not only result in graphene layers on top of the catalytic Cu thin film but also diffuse through Cu grain boundaries to the interface between Cu and underlying dielectrics. The direct evidence for bottom layer graphene at the interface between copper and silicon dioxide was provided by high-magnification TEM in cross section view of the sample. Optimization of the process parameters leads to a continuous and large-area graphene thin layers directly formed on top of the dielectric. This method allows us to achieve wafer-sized graphene on versatile insulating substrates without the need of graphene transfer. Key word: Graphene, Copper, Chemical Vapor Deposition, Raman spectroscopy, Electron backscatter diffraction (EBSD), and Transfer print.