Eta6 chemical Modification of Epitaxial Graphene: An Avenue for Non Destructive Surface Functionalization and Atomic Layer Deposition

Graphene is one atom thick planar sheet and has been applied in many fields due to its distinct properties, such as high carrier density, ballistic transport and high thermal conductivity.  Its superior properties are expected to further expand its electronic application by functionalizing graphene with other moieties. However, in most cases functionalization leads to the conversion of planar hybridized sp² state to tetrahedral sp³ state. This conversion results in the increased carrier scattering and reduced carrier density. In this talk, we demonstrate a novel η⁶ functionalization route, where epitaxial graphene can react with Chromium hexacarbonyl solution at low temperature. Raman spectroscopy and X-ray photoelectron spectroscopy are employed for surface characterization. Two Chromium peaks exist in XPS confirming (a) the grafting of chromium tri-carbonyl on the graphenic aromatic rings, and (b) interaction between the pi-cloud of graphene and the d-orbital of Chromium. The Raman 2D-peak blue shifts indicating back donation between Chromium and carbon rings. There is no D-band in Raman spectroscopy showing the sp² carbon character in the lattice is preserved. Besides, the electrical properties of functionalized graphenes and their application in sensing will also be discussed. The results clearly show that its superior properties including high carrier density, low carrier scattering and high sensitivity are maintained.