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

Abstract

Graphene was grown on a Ni (1 1 1) thin layer, used as a substrate. The Ni layer itself was grown on singlecrystal 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 boththe gas composition and the deposition temperature (900–980◦C) and cooling rate (8–16◦C/min) in thedifferent experiments. Formation of uninterruptedly grown epitaxial single layer graphene was observedover the Ni (1 1 1) thin film substrate. Epitaxial growth was proven through STM measurements. Electrondiffraction studies, also confirmed by STM, demonstrated that only one dominant orientation exists inthe graphene, both results providing evidence of the epitaxial growth. On top of the, continuous, largearea graphene flakes were also observed with sizes varying between 10 nm and 10 m. Most of the topflakes are turbostratically related to the continuous underlying epitaxial graphene layer. The formation ofthe graphene layer with constant dominant orientation was observed over millimeter wide areas. Largeareas (≈20–40 m in diameter) of continuous, epitaxial graphene, free of additional deposits and flakeswere obtained for the best set of growth parameters.