Band engineering of graphene using metal mediated oxidation
Date
2015-06-30
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Doctoral
Abstract
In the study of materials for electronic devices, there is a continuous search for new materials with useful properties. In the early 2000’s, the 2D semi-metal carbon material graphene was isolated and characterized experimentally, and found to have a variety of desirable electronic properties. Since that time research on graphene and graphene related materials has progressed at an ever growing rate as researchers seek to understand, manipulate, and enhance graphene for use in electronic devices. One arm of this research seeks to manipulate the band structure of graphene such that it behaves like a semiconductor in devices. This thesis reports a study of four graphene systems investigated to attempt to manipulate the electronic structure in graphene; Graphene/Cu, Co/Graphene/Cu, Graphene/Co/SiO2, Co/Graphene/SiO2. The properties of these systems were investigated using various X-ray spectroscopy and surface science techniques. The analysis showed that the band structure of Graphene/SiO2 may be manipulated by depositing cobalt on the graphene surface. At a low concentration, the cobalt is completely oxidized into primarily CoO, and the graphene is not heavily damaged. Oxide groups form on the graphene surface but are found to be proportional to the cobalt thickness below 1 nm. Using X-ray spectroscopy a band gap of up to 0.30 ± 0.10 eV is observed in graphene 2p states when a low concentration of cobalt forms islands on the graphene surface. The mechanism of band gap opening was interpreted using electronic structure calculations to have a contribution from both graphene oxide formation as well as the presence of CoO. These results have implications for graphene electronics and spintronics where magnetic metals can be used to induce a band gap in graphene that is stable at room temperature and under atmospheric exposure.
Description
Keywords
CVD graphene, band engineering, X-ray spetroscopy, cobalt deposition, graphene oxide
Citation
Degree
Doctor of Philosophy (Ph.D.)
Department
Physics and Engineering Physics
Program
Physics