Dominantly epitaxial growth of graphene on Ni (1Â 1Â 1) substrate

Graphene was grown on a Ni (1 1 1) thin layer, used as a substrate. The Ni layer itself was grown on single crystal sapphire (0 0 0 1). Carbon was deposited by chemical vapor deposition using a mixture of methane, argon and hydrogen at atmospheric pressure implementing a constant gas flow (4.8-5 l/min) varying both the gas composition and the deposition temperature (900-980 °C) and cooling rate (8-16 °C/min) in the different experiments. Formation of uninterruptedly grown epitaxial single layer graphene was observed over the Ni (1 1 1) thin film substrate. Epitaxial growth was proven through STM measurements. Electron diffraction studies, also confirmed by STM, demonstrated that only one dominant orientation exists in the graphene, both results providing evidence of the epitaxial growth. On top of the, continuous, large area graphene flakes were also observed with sizes varying between 10 nm and 10 μm. Most of the top flakes are turbostratically related to the continuous underlying epitaxial graphene layer. The formation of the graphene layer with constant dominant orientation was observed over millimeter wide areas. Large areas (≈20-40 μm in diameter) of continuous, epitaxial graphene, free of additional deposits and flakes were obtained for the best set of growth parameters.