Electronic Theses and Dissertations

Identifier

6013

Date

2017

Document Type

Thesis

Degree Name

Master of Science

Major

Physics

Concentration

Materials Science

Committee Chair

Jingbiao Cui

Committee Member

Mohamed Laradji

Committee Member

Xiao Shen

Committee Member

Thang Ba Hoang

Abstract

The sulfurization of MoO3 using Chemical Vapor Deposition is a common technique to synthesize MoS2 nanomaterials such as horizontal mono- and few layer nanosheets. Vertically aligned nanosheets can also be deposited under certain conditions using this method. To our knowledge, however, growth of MoS2 nanosheets with plasma enhanced CVD has not been explored so far. In this study, a remote plasma was introduced into the CVD chamber and the effect of plasma on MoS2 growth was investigated. Sulfur and MoO3 powders were used as the source materials, and the reaction temperature was controlled from 500 to 850 °C. Raman spectroscopy, x-ray diffraction, and scanning electron microscopy were used to characterize the structure and properties of the nanostructures. Introduction of plasma was found to affect the growth mode of MoS2 significantly, depending on the pressure, plasma power, and temperature. The plasma tends to promote the growth of flat nanosheets at lower pressure and high temperature or high pressure and low temperature while it enhances the growth of vertical nanosheets at high pressure and high temperature or low pressure and low temperature. These two growth modes compete with each other and the resultant morphology depends on the growth conditions and plasma power and time to be introduced. This study helps to understand the growth mechanism of MoS2 and opens an opportunity for controlling the material growth and doping by plasma.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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