ORCID

0009-0008-1256-167X

Keywords

thermogravimetric analysis, chemical vapor deposition, atomic layer deposition, precursor chemistry

Abstract

Molybdenum- and tungsten-based materials, such as pure metal, metal oxides, and metal nitrides, have been used extensively in electronics, catalysis, photovoltaics, and sensing applications. Vapor-phase growth techniques, including chemical vapor deposition (CVD) and atomic layer deposition (ALD), are commonly used to synthesize thin films of such Mo- and W-based materials. CVD and ALD growth of thin films are both highly dependent on process parameters including the properties of the precursors used, namely their volatility, thermal stability, and reactivity, which can dictate the mechanisms of growth and ultimate compositions of the resulting materials. Herein, we aim to better understand and diversify these techniques by (1) exploring the effects of space-confinement on the CVD growth of MoS2 thin films, (2) using thermogravimetric analysis (TGA) to study thermophysical parameters of molecular inorganic Mo- and W-based precursors, and (3) diversifying the range of Mo-based molecular precursors and using them for vapor-phase deposition. Firstly, space-confined CVD restricts the space between substrate and precursor, which can lead to more consistent growth of high-quality two-dimensional materials. In our approach, a growth substrate was placed directly on top of nickel foam pre-loaded with molybdenum oxide and reacted with sulfur which resulted in high-quality MoS2 monolayers. Secondly, TGA is an excellent method to study the volatility and thermal stability of precursors on a milligram scale. Using this approach, a group of eight commercially available, W-based precursors is presented, from which thermophysical parameters, including activation energy and enthalpy of sublimation/vaporization, were extracted. Lastly, the amidinate and guanidinate ligand frameworks, which have a long history in the preparation of metal organic ALD and CVD precursors across the periodic table, was leveraged with Mo(III). Presented herein is the synthesis and characterization of novel Mo(III) precursors, including the first homoleptic Mo(III) trisamidinate complex. Their use in vapor-phase thin film growth is also explored.

Completion Date

2024

Semester

Fall

Committee Chair

Jurca, Titel

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Chemistry

Format

PDF

Language

English

Document Type

Thesis

Campus Location

Orlando (Main) Campus

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