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Author: Riccardo Torsi Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Two-dimensional transition metal dichalcogenides (2D TMDs) have remained at the forefront of materials science research ever since their initial discovery over 15 years ago. Similar to graphene, 2D TMDs can be thinned down to atomic thicknesses while maintaining a clean surface free of dangling bonds. A crucial distinction from graphene is that 2D TMDs are semiconductors with band gaps that vary depending on their thickness. In addition, 2D TMDs offer other coveted characteristics, including short channel effect immunity, robust excitonic effects, and strong spin orbit coupling, making them promising for diverse applications such as ultra-scaled electronics, photonics, spintronics, flexible electronics, and biosensors. Despite extensive research and successful laboratory demonstrations showcasing the potential of 2D TMDs, the absence of commercial TMD-based products indicates that these materials are still in a developmental phase, with key challenges that need to be addressed. Since the initial mechanical exfoliation experiments used to isolate thin TMD flakes, a considerable amount of research effort has gone into realizing industrially-adaptive, scalable synthesis methods for large-area TMD films. Vapor-phase synthesis methods have made impressive progress in improving the grain size and orientation of 2D TMD films at the wafer scale. However, the absence of scalable methods for controlling defect density impedes the use of TMDs in various applications. The two-dimensional nature of TMDs make their properties particularly susceptible to crystalline defects, therefore it is crucial to understand how they are formed during synthesis and ultimately develop methods for controlling their density over large areas. Another bottleneck to 2D TMD manufacturing is the realization of doping strategies that are precise, uniform, and stable over time. Lastly, the majority of the large scale synthesis efforts focus on monolayer samples, overlooking the importance of developing growth methods for few-layer TMD films with uniform layer number control. This dissertation demonstrates approaches to control defects, dopants, and layering in the synthesis of 2D TMDs. The thesis first discusses the engineering of chalcogen vacancies in MoS2 films synthesized through metal organic chemical vapor deposition (MOCVD), achieved via post-growth annealing in controlled environments, and its effects on photophysics. Then, it delves into essential considerations about how modifications to the surface of sapphire substrates during the growth process impact the optical and electronic properties of MoS2 epilayers. Having established the synthesis of high-quality MoS2 films and native defect control, the thesis will shift to n-type doping by controlled atomic substitution of Rhenium (Re) down to ppm levels. Introducing Re dopants during the growth process is revealed to suppress chalcogen vacancy formation, leading to MoS2 films with enhanced crystallinity and transport properties. The breakthroughs discussed in this work pave the way for further exploration of dopant-defect interactions in substitutionally doped 2D semiconductors, and how they can be leveraged to improve material quality and the performance of (opto-)electronic devices. Addressing thickness control, the thesis presents a novel interrupted MOCVD growth approach for layer-by-layer epitaxy of MoS2 films with uniform layer number over large areas. Building upon the key findings presented in the thesis, the final chapter presents potential future research avenues like magnetic doping in 2D semiconductors and the deterministic growth and doping of heterodimensional TMDs.
Author: Riccardo Torsi Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Two-dimensional transition metal dichalcogenides (2D TMDs) have remained at the forefront of materials science research ever since their initial discovery over 15 years ago. Similar to graphene, 2D TMDs can be thinned down to atomic thicknesses while maintaining a clean surface free of dangling bonds. A crucial distinction from graphene is that 2D TMDs are semiconductors with band gaps that vary depending on their thickness. In addition, 2D TMDs offer other coveted characteristics, including short channel effect immunity, robust excitonic effects, and strong spin orbit coupling, making them promising for diverse applications such as ultra-scaled electronics, photonics, spintronics, flexible electronics, and biosensors. Despite extensive research and successful laboratory demonstrations showcasing the potential of 2D TMDs, the absence of commercial TMD-based products indicates that these materials are still in a developmental phase, with key challenges that need to be addressed. Since the initial mechanical exfoliation experiments used to isolate thin TMD flakes, a considerable amount of research effort has gone into realizing industrially-adaptive, scalable synthesis methods for large-area TMD films. Vapor-phase synthesis methods have made impressive progress in improving the grain size and orientation of 2D TMD films at the wafer scale. However, the absence of scalable methods for controlling defect density impedes the use of TMDs in various applications. The two-dimensional nature of TMDs make their properties particularly susceptible to crystalline defects, therefore it is crucial to understand how they are formed during synthesis and ultimately develop methods for controlling their density over large areas. Another bottleneck to 2D TMD manufacturing is the realization of doping strategies that are precise, uniform, and stable over time. Lastly, the majority of the large scale synthesis efforts focus on monolayer samples, overlooking the importance of developing growth methods for few-layer TMD films with uniform layer number control. This dissertation demonstrates approaches to control defects, dopants, and layering in the synthesis of 2D TMDs. The thesis first discusses the engineering of chalcogen vacancies in MoS2 films synthesized through metal organic chemical vapor deposition (MOCVD), achieved via post-growth annealing in controlled environments, and its effects on photophysics. Then, it delves into essential considerations about how modifications to the surface of sapphire substrates during the growth process impact the optical and electronic properties of MoS2 epilayers. Having established the synthesis of high-quality MoS2 films and native defect control, the thesis will shift to n-type doping by controlled atomic substitution of Rhenium (Re) down to ppm levels. Introducing Re dopants during the growth process is revealed to suppress chalcogen vacancy formation, leading to MoS2 films with enhanced crystallinity and transport properties. The breakthroughs discussed in this work pave the way for further exploration of dopant-defect interactions in substitutionally doped 2D semiconductors, and how they can be leveraged to improve material quality and the performance of (opto-)electronic devices. Addressing thickness control, the thesis presents a novel interrupted MOCVD growth approach for layer-by-layer epitaxy of MoS2 films with uniform layer number over large areas. Building upon the key findings presented in the thesis, the final chapter presents potential future research avenues like magnetic doping in 2D semiconductors and the deterministic growth and doping of heterodimensional TMDs.
Author: Rafik Addou Publisher: Elsevier ISBN: 032390310X Category : Technology & Engineering Languages : en Pages : 434
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: Narayanasamy Sabari Arul Publisher: Springer ISBN: 9811390452 Category : Technology & Engineering Languages : en Pages : 361
Book Description
This book presents advanced synthesis techniques adopted to fabricate two-dimensional (2D) transition metal dichalcogenides (TMDs) materials with its enhanced properties towards their utilization in various applications such as, energy storage devices, photovoltaics, electrocatalysis, electronic devices, photocatalysts, sensing and biomedical applications. It provides detailed coverage on everything from the synthesis and properties to the applications and future prospects of research in 2D TMD nanomaterials.
Author: F.A. Lévy Publisher: Springer Science & Business Media ISBN: 9401014337 Category : Science Languages : en Pages : 374
Book Description
In the last ten years, the chemistry and physics of materials with layered structures became an intensively investigated field in the study of the solid state. Research into physical properties of these crystals and especially investigations of their physical anisotropy related to the structural anisotropy has led to remarkable and perplexing results. Most of the layered materials exist in several polytypic modifications and can include stacking faults. The crystal structures are therefore complex and it became apparent that there was a great need for a review of the crystallographic data of materials approximating two-dimensional solids. This second volume in the series 'Physics and Chemistry of Materials with Layered Structures' has been written by specialists of different classes of layered materials. Structural data are reviewed and the most important relations between the structure and the chemical and physical properties are emphasized. The first three contributions are devoted to the transition metal dichalcogenides whose physical properties have been investigated in detail. The crystallographic data and crystal growth conditions are presented in the first paper. The second paper constitutes an incisive review of the phase transformations and charge density waves which have been observed in the metallic dichalcogenides. In two contributions the layered structures of newer ternary compounds are de scribed and the connection between structure and non-stoichiometry is discussed.
Author: Tianyi Zhang Publisher: ISBN: Category : Languages : en Pages :
Book Description
Two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) are an emerging family of 2D materials beyond graphene. 2D semiconducting TMDs possess a series of unique structural and functional properties, such as the presence of atomically flat surfaces without dangling bonds, layer-dependent electronic band structure, and pronounced excitonic effects, thus making them very intriguing both fundamentally and technologically. Apart from these excellent properties, another important feature of 2D TMDs is that these materials are extremely "tunable". For example, the physicochemical properties of TMDs can be effectively modulated by lattice defects (e.g., vacancies, dopants, grain boundaries) and external perturbations (e.g., strain, substrate effect, van der Waals heterostacks), providing rich opportunities for materials engineers to tailor TMD properties by means of doping, alloying, coupling TMDs with predesigned substrates, etc. Therefore, the research presented in my thesis mainly focuses on the synthesis of 2D semiconducting TMDs, the investigation of their intrinsic defects, and the development of effective substitutional doping and material transfer techniques to engineer their properties for functional applications. Chapter 1 provides an introduction to structures, properties, synthesis techniques, and defect engineering of 2D TMDs. In Chapter 2, two different additive-mediated chemical vapor deposition (CVD) approaches, involving sodium bromide and sodium cholate powders as growth promoters, are demonstrated. Pristine TMDs, alloyed MoxW1-xS2, and in-plane MoxW1-xS2-WxMo1-xS2 heterostructures are synthesized using our methods with improved grain size, yield, and reproducibility when compared to the conventional solid precursor CVD approach. Chapter 3 studies intrinsic defects and their distributions within CVD-synthesized TMD monolayers utilizing a combination of various microscopic and spectroscopic characterization techniques. The results indicate that 3d- and 4d-transition metal impurities (e.g., Cr, Fe, V, Mo) are often nonuniformly distributed within single-crystalline WS2 monolayers, leading to the photoluminescence inhomogeneity that is common in WS2. In addition, scanning tunneling microscopy/spectroscopy studies of CVD-grown WS2 have also unambiguously identified carbon-hydrogen (CH) complex as a common type of intrinsic defects. Chapter 4 reports an effective, convenient, and generalized method for in situ substitutional doping of 2D TMDs. This method is based on spin-coating and high-temperature chalcogenization of a mixture of water-soluble host precursor, dopant precursor, and growth promoter. Using this liquid phase precursor-assisted CVD method, we demonstrate the successful growth of Fe-doped WS2, Re-doped MoS2, and more complex structures such as V-doped in-plane MoxW1-xS2-WxMo1-xS2 heterostructures. In Chapter 5, we develop a clean and deterministic transfer method of 2D TMDs. We report a cellulose acetate-assisted method that transfers TMDs onto various substrates with improved micro- and nano-scale cleanliness. A deterministic transfer system is built up for placing a selected monolayer TMD to target locations on the substrate. The development of 2D TMD transfer techniques facilitates the investigation of their functional applications. As an example, the fabrication and ionic transport properties of monolayer MoS2 nanopore arrays are demonstrated in Chapter 5, and the correlation between ionic conductance and nanopore diameter distributions is carefully analyzed by combined experimental studies and molecular dynamic simulations. Finally, we provide a summary of main findings in this thesis and an outlook of future directions that can be pursued.
Author: Babak Anasori Publisher: Springer Nature ISBN: 3030190269 Category : Technology & Engineering Languages : en Pages : 534
Book Description
This book describes the rapidly expanding field of two-dimensional (2D) transition metal carbides and nitrides (MXenes). It covers fundamental knowledge on synthesis, structure, and properties of these new materials, and a description of their processing, scale-up and emerging applications. The ways in which the quickly expanding family of MXenes can outperform other novel nanomaterials in a variety of applications, spanning from energy storage and conversion to electronics; from water science to transportation; and in defense and medical applications, are discussed in detail.
Author: Alexander V. Kolobov Publisher: Springer ISBN: 3319314505 Category : Technology & Engineering Languages : en Pages : 545
Book Description
This book summarizes the current status of theoretical and experimental progress in 2 dimensional graphene-like monolayers and few-layers of transition metal dichalcogenides (TMDCs). Semiconducting monolayer TMDCs, due to the presence of a direct gap, significantly extend the potential of low-dimensional nanomaterials for applications in nanoelectronics and nano-optoelectronics as well as flexible nano-electronics with unprecedented possibilities to control the gap by external stimuli. Strong quantum confinement results in extremely high exciton binding energies which forms an interesting platform for both fundamental studies and device applications. Breaking of spatial inversion symmetry in monolayers results in strong spin-valley coupling potentially leading to their use in valleytronics. Starting with the basic chemistry of transition metals, the reader is introduced to the rich field of transition metal dichalcogenides. After a chapter on three dimensional crystals and a description of top-down and bottom-up fabrication methods of few-layer and single layer structures, the fascinating world of two-dimensional TMDCs structures is presented with their unique atomic, electronic, and magnetic properties. The book covers in detail particular features associated with decreased dimensionality such as stability and phase-transitions in monolayers, the appearance of a direct gap, large binding energy of 2D excitons and trions and their dynamics, Raman scattering associated with decreased dimensionality, extraordinarily strong light-matter interaction, layer-dependent photoluminescence properties, new physics associated with the destruction of the spatial inversion symmetry of the bulk phase, spin-orbit and spin-valley couplings. The book concludes with chapters on engineered heterostructures and device applications such as a monolayer MoS2 transistor. Considering the explosive interest in physics and applications of two-dimensional materials, this book is a valuable source of information for material scientists and engineers working in the field as well as for the graduate students majoring in materials science.
Author: Chi Sin Tang Publisher: John Wiley & Sons ISBN: 3527838767 Category : Technology & Engineering Languages : en Pages : 357
Book Description
Two-Dimensional Transition-Metal Dichalcogenides Comprehensive resource covering rapid scientific and technological development of polymorphic two-dimensional transition-metal dichalcogenides (2D-TMDs) over a range of disciplines and applications Two-Dimensional Transition-Metal Dichalcogenides: Phase Engineering and Applications in Electronics and Optoelectronics provides a discussion on the history of phase engineering in 2D-TMDs as well as an in-depth treatment on the structural and electronic properties of 2D-TMDs in their respective polymorphic structures. The text addresses different forms of in-situ synthesis, phase transformation, and characterization methods for 2D-TMD materials and provides a comprehensive treatment of both the theoretical and experimental studies that have been conducted on 2D-TMDs in their respective phases. Two-Dimensional Transition-Metal Dichalcogenides includes further information on: Thermoelectric, fundamental spin-orbit structures, Weyl semi-metallic, and superconductive and related ferromagnetic properties that 2D-TMD materials possess Existing and prospective applications of 2D-TMDs in the field of electronics and optoelectronics as well as clean energy, catalysis, and memristors Magnetism and spin structures of polymorphic 2D-TMDs and further considerations on the challenges confronting the utilization of TMD-based systems Recent progress of mechanical exfoliation and the application in the study of 2D materials and other modern opportunities for progress in the field Two-Dimensional Transition-Metal Dichalcogenides provides in-depth review introducing the electronic properties of two-dimensional transition-metal dichalcogenides with updates to the phase engineering transition strategies and a diverse range of arising applications, making it an essential resource for scientists, chemists, physicists, and engineers across a wide range of disciplines.
Author: Dongzhi Chi Publisher: Elsevier ISBN: 0128165898 Category : Technology & Engineering Languages : en Pages : 339
Book Description
2D Semiconductor Materials and Devices reviews the basic science and state-of-art technology of 2D semiconductor materials and devices. Chapters discuss the basic structure and properties of 2D semiconductor materials, including both elemental (silicene, phosphorene) and compound semiconductors (transition metal dichalcogenide), the current growth and characterization methods of these 2D materials, state-of-the-art devices, and current and potential applications. - Reviews a broad range of emerging 2D electronic materials beyond graphene, including silicene, phosphorene and compound semiconductors - Provides an in-depth review of material properties, growth and characterization aspects—topics that could enable applications - Features contributions from the leading experts in the field
Author: Jan Stehr Publisher: Woodhead Publishing ISBN: 0081020546 Category : Technology & Engineering Languages : en Pages : 309
Book Description
Defects in Advanced Electronic Materials and Novel Low Dimensional Structures provides a comprehensive review on the recent progress in solving defect issues and deliberate defect engineering in novel material systems. It begins with an overview of point defects in ZnO and group-III nitrides, including irradiation-induced defects, and then look at defects in one and two-dimensional materials, including carbon nanotubes and graphene. Next, it examines the ways that defects can expand the potential applications of semiconductors, such as energy upconversion and quantum processing. The book concludes with a look at the latest advances in theory. While defect physics is extensively reviewed for conventional bulk semiconductors, the same is far from being true for novel material systems, such as low-dimensional 1D and 0D nanostructures and 2D monolayers. This book fills that necessary gap. - Presents an in-depth overview of both conventional bulk semiconductors and low-dimensional, novel material systems, such as 1D structures and 2D monolayers - Addresses a range of defects in a variety of systems, providing a comparative approach - Includes sections on advances in theory that provide insights on where this body of research might lead
Author: Riccardo Torsi
Author: Riccardo Torsi
Author: Rafik Addou
Author: Narayanasamy Sabari Arul
Author: F.A. Lévy
Author: Tianyi Zhang
Author: Babak Anasori
Author: Alexander V. Kolobov
Author: Chi Sin Tang
Author: Dongzhi Chi
Author: Jan Stehr