Structural and electronic properties of grapheme-based materials

Jasmine J. Hargrove, Clark Atlanta University

Abstract

This thesis includes work done on graphene-based materials, examining their unique electronic properties using first-principles density-functional calculations. Abinitio methods such as density functional theory (DFT) are widely accepted as computational methods in condensed matter and materials physics. We begin by studying the electronics properties of graphene intercalation compounds (GICs). In order for bilayer graphene to be used for field effect transistors, the GIC must decouple the adajent graphene layers and decrease interlayer interaction. We conducted a theoretical study in order to elucidate the electronic characteristics of methane intercepted bilayer graphene under a perpendicularly applied electric field. We show that methane intercalated graphene can make a promising material for implimentations of graphene based field effect transistors since it has a controllable band gap.

Finally, we show the evolution of band structure of graphene treated with fluorinated olefins through covalent functionalization. The bonding of fluorine to the graphene surface results in the transformation of orbital hybridization from sp2 to sp3. We find that the modification of graphene's electronic properties by such a drastic change in hybridization can lead to the elimination of the bands near the Fermi level and the opening of a band gap. We hope this work will help bring to light the promising electronic properties of graphene based materials for future device applications.