Award Date

May 2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical and Computer Engineering

First Committee Member

Biswajit Das

Second Committee Member

Emma Regentova

Third Committee Member

Rama Venkat

Fourth Committee Member

Christopher Stream

Number of Pages

82

Abstract

Graphene is an important nanoscale material with unique electronic and optical properties. Due to its many potential applications, grapheme was the subject of a Nobel Prize in physics 2010; Andre Geim and Kostya Novoselov of Manchester University received the Nobel Prize for demonstrating the ability to create single atom thick graphene layers from bulk graphite. Since then, many alternative synthesis techniques and device applications of graphene have been explored. An important and unique property of graphene is its excellent thermal properties. Graphene has a two dimensional structure and the thermal properties are significantly different than three dimensional bulk materials. Using graphene by itself or as a composite for thermal management presents new opportunities for its impact on numerous applications including green technologies for power generation. .

While graphene has been initially created using the exfoliation technique, it is widely believed that chemical vapor deposition (CVD) and plasma enhanced CVD (PECVD) techniques are better suited for large scale production of graphene. As such there has been significant effort in the synthesis of graphene by using these techniques. In particular, PECVD technique seems promising due to its lower growth temperature as it may be applied to a variety of substrates. Unfortunately, the quality of graphene created by CVD and PECVD techniques so far have been inferior to that made by the exfoliation technique; they are typically polycrystalline with grain size depending on specific process parameters.

The nanotechnology research group at UNLV has developed a technique for the synthesis of uniform diameter high quality carbon nanotubes by a process called catalyst engineering where a nanoparticle of the catalyst is used instead of a thin film. Since nanoparticle catalysts have better efficiency compared to thin films, this process has allowed the synthesis of superior quality carbon nanotubes. We believe that similar catalyst engineering can be applied for the synthesis of superior quality graphene tin films. Copper thin films are widely used as catalyst for the synthesis of graphene. In this project, we use copper nanoparticles to synthesize graphene using the PECVD technique in UNLV’s unique cluster tool Nanosys. While scanning electron microscope imaging shows synthesis of some carbon structures, the formation of graphene could not be confirmed by Raman spectroscopy measurement, possibly due to the small mass of the structures. From our investigation, it became apparent that a more systematic approach with additional resources will be needed to synthesize graphene by this method. As such, the focus in this research was redirected towards the development of another platform for the synthesis of graphene using catalyst engineering.

The nanotechnology research group has extensive experience in the synthesis of nanostructures using anodized alumina as a template. In this research, we investigated and developed a platform for the fabrication copper nanowires using an anodized alumina template that can be used for the synthesis of graphene using the PECVD technique. The project also investigated adhesion properties of such structures on the substrate. In addition, an interesting outcome of this project is the development of a new technique for the fabrication of nanoporous thin film membranes.

Disciplines

Computer Engineering | Electrical and Computer Engineering

Language

English


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