Date of Award

7-1-2013

Degree Type

Thesis

University or Center

Clark Atlanta University(CAU)

School

School of Arts and Sciences

Degree Name

M.S.

Department

Physics

First Advisor

Dr. Xiao-Oian Wang

Second Advisor

Dr. Michael P. Williams

Third Advisor

Dr. Darkeyah G. Reuven

Abstract

Graphene is a two-dimensional system consisting of a single planar layer of carbon atoms with hexagonal arrangement. Various approaches have been proposed to control its physical and electronic properties. Graphite intercalation compounds are materials formed by inserting molecular layers of compounds between stacked sheets of graphene. We have studied the physical and electronic responses of two graphene layers intercalated with gold cluster. Quasi free-standing graphene with Dirac fermion behavior has been recently demonstrated through gold intercalated epitaxial graphene. Herein, we investigate the electronic characteristics of gold-intercepted epitaxial graphene under a perpendicularly applied electric field. Evolution of the band structure of intercalated epitaxial graphene as a function of the bias is investigated by means of density-functional theory including interlayer van der Waals interactions. Our results indicate that goldintercalated epitaxial graphene can lead to tunable band gap with the applied bias, which is important for future device.

Hexagonal boron-nitride (fc-BN) is an ideal substrate for graphene due to its dielectric, insulating, and polarizing features. Our first-principles investigation reveals that the interaction of the /i-BN substrate with graphene induces a band gap. The zigzagedged graphene and /i-BN nanoribbon possess intrinsic half-metalicity, whereas the reconstructed edges with heptagonal and pentagonal alterations yield metallic states. The application of a transverse electric bias to a graphene boron nitride nanoribbon (GBNNR) promotes a transition from exhibiting semiconducting states to half metallic properties while GBNNR with reconstructed edges undergo transition from metallic to semiconducting properties.

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