Date of Graduation

Summer 2013

Degree

Master of Science in Materials Science

Department

Physics, Astronomy and Materials Science

Committee Chair

Kartik Ghosh

Keywords

graphene, 2-D materials, structural properties, electrical properties, field effect transistors

Subject Categories

Materials Science and Engineering

Abstract

Graphene is the first discovered 2-D material. Its structure is composed of a honeycomb shaped lattice composed of sp2 bonded carbon atoms. Its structural properties can be studied in great detail using Raman spectroscopy. However, of great interest are its electrical properties. Theoretically, graphene's charge carriers can be tuned continuously to values as high as 1013 cm-2 and its mobility can be as high as on the order of 120,000 cm2/(V*s). While this entices researchers, there are difficulties due to graphene's linear IV curve and the lack of control over its doping levels. This research seeks to use laser irradiation to modify graphene's properties. In the first instance, laser irradiation can be used to remove excess residue, thereby allowing graphene to better achieve its mobility potential. Nonetheless, one must remain cognizant that this process may cause differences in graphene's structural properties that may alter its electrical characteristics. Using field effect transistor measurements and Hall Effect measurements, this research addresses these alterations. It was found that laser irradiation in vacuum causes increased carrier concentration and decreased mobility. Alternatively, annealing the sample in forming gas causes decreased carrier concentration and increased mobility. Hence, it is seen that the doping level of the graphene can be modified using laser irradiation and annealing in different environments.

Copyright

© Michelle Nicole Langhoff

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