Date of Award

5-1-2011

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 D. Williams

Third Advisor

Dr. Ryza Musin

Abstract

Graphane is a two-dimensional system consisting of a single planar layer of fully saturated carbon atoms, which has recently been realized experimentally through hydrogenation of graphene membranes. We have studied the stability of chair, boat, and twist-boat graphane structures using first-principles density functional calculations. Our results indicate that locally stable twist-boat membranes significantly contribute to the experimentally observed lattice contraction. The band gaps of graphane nanoribbons decrease monotonically with the increase of the ribbon width and are insensitive to the edge structure. We also have studied the electronic structural characteristics in a hydrogenated bilayer graphene under a perpendicular electric bias. The bias voltage applied between the two hydrogenated graphene layers allows continuously tuning the band gap and leads a transition from semiconducting to metallic state. Desorption of hydrogen from one layer in the chair conformation yields a ferromagnetic semiconductor with tunable band gap.

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