Synthesis of Two-dimensional Molybdenum Disulfide Atomic Film by Chemical Vapor Deposition PDF Download
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Author: Hung Duc Nguyen
Publisher:
ISBN:
Category : Chemical vapor deposition
Languages : en
Pages :
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Author: Hung Duc Nguyen
Publisher:
ISBN:
Category : Chemical vapor deposition
Languages : en
Pages :
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Author: Carl Morris Gross (III)
Publisher:
ISBN:
Category : Chemical vapor deposition
Languages : en
Pages : 40
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Book Description
Two-dimensional materials, or materials that are only one atomic layer thick, have seen much research in recent years because of their interesting electrical properties. The first of these materials, graphene, was found to have incredible electrical properties but lacked a bandgap in intrinsic films. Without a bandgap, graphene cannot create transistors that can be shut off. Molybdenum disulfide, however, is a two-dimensional semiconductor with a large bandgap. The main issue of molybdenum disulfide is that synthesized films are a much lower quality than their exfoliated counterparts. For molybdenum disulfide to be able to be used practically, a method of synthesis must be found that can reliably create quality large area monolayer films. In this thesis, three methods of molybdenum disulfide film synthesis are presented. Methods implemented used a tube furnace as a chemical vapor deposition system to evaporate source materials to synthesize thin films of molybdenum disulfide. An exploration into the different synthesis parameters shows optimal conditions for these specific methods. Then a discussion of these different methods is presented by judging films grown by using these methods on relevant criteria. This work shows methods to synthesize large area, polycrystalline, small grain, multilayer films, both intrinsic and doped, and to synthesize small area, single crystal and polycrystalline, monolayer films of molybdenum disulfide.
Author: Zachary Durnell Ganger
Publisher:
ISBN:
Category : Chemical vapor deposition
Languages : en
Pages : 96
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Graphene has successfully been a 2D material applied in various fields, but it is not the most appropriate candidate for many electronic devices unless its bandgap structure is tuned through functionalization. Among all other 2D material families, transition metal dichalcogenides (TMDs), represented by molybdenum disulfide (MoS2), are promising and emerging in power electronics due to their large direct bandgap and other electronic properties. 2D MoS2 has been fabricated through different approaches such as mechanical exfoliation, chemical etching, and chemical vapor deposition (CVD). The current major challenge in fabricating 2D MoS2 films is to produce a high-quality large-area monolayer film at a controlled condition. This thesis study is to grow 2D MoS2 films by CVD method at various experimental settings and to characterize the size, thickness, and morphology of the films, towards finding an optimal processing condition. Experimental settings for the growth parameters include the precursor amounts and placements, growth time, growth temperature, carrier gas flow rate, substrates, and seeding promoters. The growth films are characterized with the help of optical microscopy, Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). It is found that 1) MoS2 growth is sensitive to the carrier flow rate and temperature; and 2) 2D MoS2 grain size and areal coverage are correlated with grow time as well as the distance from the promoter PTAS (perylene-3,4,9,10-tetracarboxylic acid tetrapotassium salt) resource. Existence of monolayer MoS2, in the presence of PTAS promotor, is confirmed with Raman Spectroscopy and AFM. Multilayer MoS2 films with grains up to several hundreds of micrometers, confirmed with optical microscopy, SEM and Raman, are successfully grown on clean Si/SiO2 substrate in the presence of PTAS promotor vapor in the vicinity. Growth of monolayer/multilayer MoS2 on sapphire and graphene was also demonstrated
Author: Ka-Yi Tsang
Publisher: Open Dissertation Press
ISBN: 9781361380963
Category :
Languages : en
Pages :
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This dissertation, "Two Dimensional Transition Metal Dichalcogenides Grown by Chemical Vapor Deposition" by Ka-yi, Tsang, 曾家懿, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: An atomically thin film of semiconducting transition metal dichalcogenides (TMDCs) is emerging as a class of key materials in chemistry and physics due to their remarkable chemical and electronic properties. The TMDCs are layered materials with weak out-of-plane van der Waals (vdW) interaction and strong in-plane covalent bonding enabling scalable exfoliation into two-dimensional (2D) layers of atomic thickness. The growth techniques to prepare these 2D TMDC materials in high yield and large scale with high crystallinity have attracted intensive attention recently because of the new properties and potentials in nano-elctronic, optoelectronic, spintronic and valleytronic applications. In this thesis, I develop methods for the chemical synthesis of 2D TMDCs films. The relevant growth mechanism and material characteristics of these films are also investigated. Molybdenum disulfide (MoS2) is synthesized by using molybdenum trioxide (MoO3) and sulfur (S) powder as the precursor. The films are formed on substrate pre-treated with reduced graphene oxide as the catalyst. However, this method cannot be extended to other TMDC materials such as molybdenum diselenide (MoSe2) and tungsten diselenide (WSe2) because reduced graphene oxide (rGO) reacts with selenium to form alloy materials rather than TMDC films. At the same time, the conversion of MoO3 to MoSe2 or that of tungsten trioxide (WO3) to WSe2 without the assistance of hydrogen in the chemical reaction is not thermodynamically feasible because the oxygen in the metal oxide cannot be replaced by selenium due to lower reactivity of the latter. On the other hand, I demonstrate that MoSe2 film can be synthesized directly by using MoSe2 and Se powder. Furthermore, the method of sulfurization or selenization of pre-deposited metal film can be promising due to precise thickness/size controls. Finally, some perspectives on the engineering challenges and fabrication methods of this family of materials will be given. Subjects: Transition metal compounds - Synthesis Chalcogenides - Synthesis
Author: Sol Torrel
Publisher:
ISBN:
Category : Molybdenum disulfide
Languages : en
Pages : 176
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In this doctoral thesis work, two-dimensional (2D) molybdenum disulfide (MoS2) single crystals have been synthesized, characterized, and tribologically studied. Specifically, detailed analyses of processes that occur during chemical vapor deposition (CVD) of atomically thin MoS2 have been performed to understand key mechanisms responsible for reproducible growth of high quality materials. To this end, literature survey of growth parameters was performed and compared with original experiments performed here. The methods and mechanisms of nucleation and growth of large-area, single- and few-layer MoS2 are described with emphasis on variable control and repeatability. The synthesis work performed here provides new insights into the challenges of reproducible MoS2 growth using CVD. Following the CVD work, the thesis research included phase transformation of MoS2 - building on ongoing research in our group. The aim of this part of the research was to understand how chemistry can change the structural phase of 2D MoS2. More specifically, this work was performed to determine the root cause of challenges that are encountered during phase transformation. Finally, my primary focus and most of my efforts were devoted to study of the tribological properties of 2D MoS2 to further develop fundamental understanding of friction on the atomic level. Atomic force microscopy (AFM) was used to measure nanoscale tribological properties of semiconducting and metallic monolayer MoS2 to study the influence of electronic structure on friction behavior. Furthermore, various multilayer semiconducting polytypes of MoS2 were studied to elucidate the phononic contribution to friction. Electronic and phononic properties of this nanomaterial were probed, analyzed, and correlated through AFM and Raman spectroscopy. As a result, a preliminary methodology for remote prediction of friction behavior via laser excitation has been developed.
Author: Weiquan Zhan
Publisher: OAE Publishing Inc.
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 43
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Book Description
Molybdenite (MoS2) has been widely used in the fields of catalysis, desalination, energy storage and conversion and optoelectronics as a result of its unique crystal structures and unusual properties. In the last decade, the modification of the surface, structural and semiconducting properties of zero-, two- and three-dimensional (0D, 2D and 3D) MoS2 for enhanced applications has attracted considerable attention. In this review, we summarize the synthesis, modification methods and application of 0D, 2D and 3D MoS2. The unique structures and properties of 0D, 2D and 3D MoS2 are first introduced. Next, the preparation methods of 0D, 2D and 3D MoS2 are summarized. The modification methods, including surface, structural and composite engineering, for enhancing the physical and chemical properties of 0D, 2D and 3D are also discussed. Finally, inspired by natural and modified MoS2, future suggestions for the design of novel 0D, 2D and 3D MoS2 for various applications are also suggested. This review offers new insights into the design and construction of novel and efficient 0D, 2D and 3D MoS2 for practical applications.
Author: Nicholas Simonson
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Two-dimensional (2D) transition metal dichalcogenides (TMDs) have demonstrated promising proof-of-concept performance in electronic and optoelectronic applications. Aside from desirable electronic properties, TMDs also exhibit inherent flexibility and transparency due to their atomically thin nature. Fabrication of TMD-based nanoelectronics directly on transparent, flexible substrates remains a challenge due to the high processing temperatures required for synthesis of highly crystalline material, temperatures which are generally not compatible with industrially relevant multicomponent glasses such as flexible Willow Glass, LCD display Lotus Glass, and the ubiquitous Gorilla Glass. This dissertation addresses the limitations of TMD growth on glass by examining the impact of glass surface chemistry, synthesis parameters, and alkali ion species on the nucleation and growth of MoS2 and WSe¬2 using metalorganic chemical vapor deposition (MOCVD). Chapter 1 introduces the necessary background, overarching hypothesis, technical motivation, and relevant literature on low-temperature CVD, alkali-assisted CVD, and CVD-on-glass of TMDs. Chapter 2 discusses the requisite experimental methods, particularly the synthesis processes and characterization techniques used. Chapter 3 presents the findings regarding initial synthesis optimization of MoS2 and WSe2 as well as alkali-assisted CVD. Chapter 3 also presents findings regarding the effect of glass chemistry on low-temperature CVD of TMDs through use of alkali-containing glass and substrate surface treatment. Chapter 4 introduces a carbon-free H2S precursor to further improve domain size and electronic properties, and examines the benefits of a combined approach involving various alkali-containing glass chemistries, alkali halides, and H2S-based growth. Chapter 5 includes MoS2 synthesis of vertically oriented films for electrochemical catalysis and lateral MoS2-graphene heterostructures. Lastly, Chapter 6 discusses the implications and future work in the growth of device-quality TMDs directly on multicomponent glasses.
Author: Satyabrata Jit
Publisher: Elsevier
ISBN: 0128176792
Category : Technology & Engineering
Languages : en
Pages : 285
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Book Description
2D Nanoscale Heterostructured Materials: Synthesis, Properties, and Applications assesses the current status and future prospects for 2D materials other than graphene (e.g., BN nanosheets, MoS2, NbSe2, WS2, etc.) that have already been contemplated for both low-end and high-end technological applications. The book offers an overview of the different synthesis techniques for 2D materials and their heterostructures, with a detailed explanation of the many potential future applications. It provides an informed overview and fundamentals properties related to the 2D Transition metal dichalcogenide materials and their heterostructures. The book helps researchers to understand the progress of this field and points the way to future research in this area. - Explores synthesis techniques of newly evolved 2D materials and their heterostructures with controlled properties - Offers detailed analysis of the fundamental properties (via various experimental process and simulations techniques) of 2D heterostructures materials - Discusses the applications of 2D heterostructured materials in various high-performance devices
Author: Rafik Addou
Publisher: Elsevier
ISBN: 032390310X
Category : Technology & Engineering
Languages : en
Pages : 434
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Book Description
Defects in Two-Dimensional Materials addresses the fundamental physics and chemistry of defects in 2D materials and their effects on physical, electrical and optical properties. The book explores 2D materials such as graphene, hexagonal boron nitride (h-BN) and transition metal dichalcogenides (TMD). This knowledge will enable scientists and engineers to tune 2D materials properties to meet specific application requirements. The book reviews the techniques to characterize 2D material defects and compares the defects present in the various 2D materials (e.g. graphene, h-BN, TMDs, phosphorene, silicene, etc.). As two-dimensional materials research and development is a fast-growing field that could lead to many industrial applications, the primary objective of this book is to review, discuss and present opportunities in controlling defects in these materials to improve device performance in general or use the defects in a controlled way for novel applications. Presents the theory, physics and chemistry of 2D materials Catalogues defects of 2D materials and their impacts on materials properties and performance Reviews methods to characterize, control and engineer defects in 2D materials
Author: Filippo Giannazzo
Publisher: MDPI
ISBN: 3038976067
Category : Science
Languages : en
Pages : 265
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Book Description
This book is a printed edition of the Special Issue "Integration of 2D Materials for Electronics Applications" that was published in Crystals
