Synthesis of Graphene by Chemical Vapour Deposition

Chemical vapour deposition is used to grow large area graphene with an aim to produce massive single crystals. We are focussing on using copper foils as a catalyst and developing a deep understanding of the factors that influence growth.

We showed that graphene grown on copper is not self-limiting to monolayer coverage and has potential for bilayer and other few-layer graphene structures. It is possible to grow few layer graphene domains and we have shown using electron diffraction that these are single crystals. By appropriate control of hydrogen, we demonstrated that well defined hexagonal shaped few layer graphene domains on copper can be produced, as well as large monolayer hexagons.

Graphene is transferred to a wide range of substrates, such as glass, plastic, silicon wafers and also suspended. Suspending graphene on TEM grids, shown below, enables us to study its properties without any substrate interaction. Our research aims to provide ultra-clean suspended graphene that is free from surface contamination. The atomic structure of inorganic nanomaterials, such as the highly fluorescent Mn doped ZnSe quantum dots, are studied in high detail using suspended graphene membranes. We have studied small molecules and atoms on the surface of few layer graphene and used focused electron beam irradiation to catalyse the formation of organic linear chain molecules with direct anchor attachment to the surface.

We undertake tilt-dependent electron diffraction measurements and then track the intensity of peaks in the patterns to confirm monolayer formation. The intensity of SAED peaks in few-layer graphene can oscillate as the sample is tilted. Monolayer graphene exhibits a gradual reduction in the SAED peak intensity as tilt is increased, and broadening in the peak FWHM from the rippling.