Download or read book Defect driven Processing of Two dimensional Transition Metal Dichalcogenides written by Kevin Christopher Bogaert and published by . This book was released on 2019 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-dimensional transition metal dichalcogenides (TMDs) are an emerging class of semiconductor materials that offer exciting new properties for future electronic and optoelectronic applications. However, many ongoing challenges related to synthesis and processing must be overcome before this nascent technology can become industrially viable. In this thesis, processing-related phenomena relevant to the fabrication of TMD heterostructures, alloys, and nanoporous membranes are presented. This thesis begins with an investigation of the role of substrate temperature in two-step chemical vapor deposition (CVD) growth of MoS2/WS2 heterostructures. We demonstrate diffusion-mediated synthesis of inverted lateral heterostructures following low MoS2 growth temperatures in the second CVD step and homogeneous Mo[subscript x]W[subscript 1-x]S2 alloyed crystals following higher MoS2 growth temperatures. Investigating the nature of this diffusion-mediated process, we identify an energetically favorable atomistic model proposing that transition metal diffusion is driven by a heterogeneous distribution of sulfur vacancies. This model is corroborated by the synthesis of a composition-graded Mo[subscript x]W[subscript 1-x]S2 alloy crystals in which the final-stage spatial distribution of transition metal atoms correlates with intermediate-stage distribution of point defects. These heterogeneous crystals allow for correlation of the local optical properties with the local composition, demonstrating a variation in photoluminescence intensity spanning two orders of magnitude and reaching the maximum value for equicompositional alloy Mo0.5W0.5S2 (x=0.5). Furthermore, the correlation between intermediate-stage distribution of point defects and final-stage spatial distribution of transition metal atoms enables the opportunity for bespoke patterning. Utilizing a laser annealing technique, we demonstrate the ability to locally induce defects that define the regions of preferential nucleation during subsequent CVD growth. Finally, defect processing is also demonstrated in nanoporous TMD membrane applications. Combining modeling with experimentation, we demonstrate the relationship between vacuum annealing time and temperature with nanopore properties such as average radius and edge structure. Control of these properties is essential for the fabrication of functional nanoporous membrane devices for sensing, filtration, and energy applications. This thesis motivates further work on TMD processing in pursuit of developing a fundamental understanding of the defect-driven diffusion mechanism, a larger library of interesting TMD compositions and structures, as well as industrially viable TMD devices.

Download or read book Two Dimensional Transition Metal Dichalcogenides written by Narayanasamy Sabari Arul and published by Springer. This book was released on 2019-07-30 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Two Dimensional Transition Metal Dichalcogenides written by Alexander V. Kolobov and published by Springer. This book was released on 2016-07-26 with total page 545 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Engineering Defects Dopants and Layering in 2D Transition Metal Dichalcogenides written by Riccardo Torsi and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Defects in Two Dimensional Materials written by Rafik Addou and published by Elsevier. This book was released on 2022-02-14 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Two Dimensional Transition Metal Dichalcogenides written by Chi Sin Tang and published by John Wiley & Sons. This book was released on 2023-11-14 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Two Dimensional Transition Metal Dichalcogenides written by Chi Sin Tang and published by John Wiley & Sons. This book was released on 2023-11-08 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Two dimensional Transition Metal Dichalcogenides written by Tianyi Zhang and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book 2D Monoelemental Materials Xenes and Related Technologies written by Zongyu Huang and published by CRC Press. This book was released on 2022-04-19 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Monoelemental 2D materials called Xenes have a graphene-like structure, intra-layer covalent bond, and weak van der Waals forces between layers. Materials composed of different groups of elements have different structures and rich properties, making Xenes materials a potential candidate for the next generation of 2D materials. 2D Monoelemental Materials (Xenes) and Related Technologies: Beyond Graphene describes the structure, properties, and applications of Xenes by classification and section. The first section covers the structure and classification of single-element 2D materials, according to the different main groups of monoelemental materials of different components and includes the properties and applications with detailed description. The second section discusses the structure, properties, and applications of advanced 2D Xenes materials, which are composed of heterogeneous structures, produced by defects, and regulated by the field. Features include: Systematically detailed single element materials according to the main groups of the constituent elements Classification of the most effective and widely studied 2D Xenes materials Expounding upon changes in properties and improvements in applications by different regulation mechanisms Discussion of the significance of 2D single-element materials where structural characteristics are closely combined with different preparation methods and the relevant theoretical properties complement each other with practical applications Aimed at researchers and advanced students in materials science and engineering, this book offers a broad view of current knowledge in the emerging and promising field of 2D monoelemental materials.

Download or read book 2D Metal Carbides and Nitrides MXenes written by Babak Anasori and published by Springer Nature. This book was released on 2019-10-30 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book FACILE SYNTHESIS ROUTES DIRECTED ASSEMBLY AND BIOLOGICAL APPLICATIONS OF TWO DIMENSIONAL TRANSITION METAL DICHALCOGENIDES written by Zhong Lin and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis focuses on two-dimensional (2D) transition metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2). The controlled synthesis, directed assembly, and biological applications of 2D TMDs are investigated. Chapter 1 introduces the fundamentals of 2D TMDs, and reviews defect engineering of these atomic layers. Synthesis of single-phased MoS2 and WS2 monolayers has been reported previously. Chapter 2 reports synthesis of MoxW1-xS2 monolayer alloys by chemical vapor deposition. The as grown MoxW1-xS2 single crystals show gradual concentration profiles of transition metal atoms. The in-plane compositional gradient results in continuously tunable bandgaps. Transition metals form one-dimensional stripes in central regions of triangular-shaped crystals. Two types of synthetic defects, i.e. metal dopants and chalcogen vacancies, are observed to couple with each other in the alloys. The non-random and anisotropic alloys provide a rich setting to study 2D growth kinetics and nanoscale defect engineering. Chemical vapor deposition of TMDs generally requires a high growth temperature, which limits its applications in certain areas such as flexible electronics. In Chapter 3, the synthesis temperature is reduced by introducing tellurium powders into the growth precursors. The addition of tellurium does not affect the phase purity or crystallinity of the as-synthesized MoS2 and WS2 monolayers. These materials show optical and electrical performance comparable to those synthesized at higher temperatures. Established transfer methods of 2D TMDs include wet transfer and deterministic transfer. Chapter 4 demonstrates controlled and scalable transfer of monolayer WS2 triangles on a substrate using electric-field-assisted assembly. WS2 monolayers are selectively positioned on a guiding electrode structure using the dielectrophoretic force and its torque acting on the monolayers. Triangular sheets assemble with a preferential orientation relative to the electrodes. The assembly process neither deforms monolayer sheets, nor introduces structural defects to the materials, as confirmed by optical spectroscopies. The assembly method offers an alternative to conventional transfer methods in 2D monolayer integrations.The extraordinary photoluminescence of semiconducting TMDs makes them attractive for cellular imaging. Chapter 5 studies how cells interact with 2D TMDs. It is observed that certain cells digest monolayer WS2, become light-emitting afterwards, and are able to pass this light-emitting characteristic to their progeny cells. The residual WS2 monolayers, after interaction with cells, become structurally defective. This work may trigger further studies on 2D/bio interfaces.

Download or read book Advanced Applications of 2D Nanostructures written by Subhash Singh and published by Springer Nature. This book was released on 2021-08-21 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on both recent advances and the applications of two-dimensional (2D) nanomaterials in different fields. This book encapsulates all the aspects related to 2D nanomaterials and their applications. It provides scientific and technological insights on novel routes of design and fabrication of few layered nanostructures and their hetero structures based on a variety of 2-D layered materials. It also covers a wide range of industrial applications of 2D nanomaterials. It emphasizes on the detailing of the various characterization techniques used. The book will be a valuable reference for beginners, researchers, and professionals interested in nano-materials and allied fields.

Download or read book Two dimensional Materials written by Pramoda Kumar Nayak and published by BoD – Books on Demand. This book was released on 2016-08-31 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are only a few discoveries and new technologies in materials science that have the potential to dramatically alter and revolutionize our material world. Discovery of two-dimensional (2D) materials, the thinnest form of materials to ever occur in nature, is one of them. After isolation of graphene from graphite in 2004, a whole other class of atomically thin materials, dominated by surface effects and showing completely unexpected and extraordinary properties, has been created. This book provides a comprehensive view and state-of-the-art knowledge about 2D materials such as graphene, hexagonal boron nitride (h-BN), transition metal dichalcogenides (TMD) and so on. It consists of 11 chapters contributed by a team of experts in this exciting field and provides latest synthesis techniques of 2D materials, characterization and their potential applications in energy conservation, electronics, optoelectronics and biotechnology.

Download or read book Functionalization of Two Dimensional Transition Metal Dichalcogenides written by He Liu and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical surface functionalization has been widely used to tune the electronic, optical, and catalytic properties of two-dimensional (2D) transition metal dichalcogenides (TMDs). This thesis focuses on applying novel chemical functionalization methods to functionalize 2D TMD materials to tune its physical and chemical properties. The controlled tuning of these properties can then be utilized to improve the performance of 2D TMD-based devices and other applications such as sensing and catalysis. In chapter one, this thesis introduces current research fronts of 2D materials including graphene, TMDs and hexagonal boron nitride (hBN). The common synthesis and functionalization methods are also categorized and discussed in this chapter. Chapters two to four focus on individual research projects where I played a leading role and are summarized below. In chapter two, we demonstrate the spontaneous chemical functionalization via coordination of Au/Ag single atoms on monolayer MoS2. In this work, we developed an innovative route to functionalize monolayers of MoS2 with individual Au atoms via the formation of S-Au-Cl coordination complexes ([Au(MoS2)Clx]) on the TMD surface. The [Au(MoS2)Clx] coordination complexes were synthesized by taking advantage of the lone pair electrons of the S atoms present in the MoS2 lattice. In chapter three, we continue studying the coordination reaction between transition metals that include Fe, Co, Ni, Cu, Zn and MoS2. We studied the formation of these coordination complexes on MoS2 monolayers and correlate their properties with classical coordination complexes. Chapter four discusses surface enhanced Raman spectroscopy (SERS) using Au nanoparticles (Au NPs) functionalized MoS2. In this work, monolayer MoS2 is transferred on top of a monolayer of Au nanoparticles in order to achieve constructive interference of electrochemical enhancement and charge-transfer-based chemical enhancement. In the Appendix, we describe defect engineering to create vacancies and exposed edges in MoS2. We demonstrate that defect engineering via cryo-milling can be utilized to activate the inert sites in these materials to improve their Hydrogen evolution reaction (HER) catalytic performances. Chapter 2 is adapted from a published article which I am the first author. Chapters 3 and 4 are adapted from manuscripts in preparation which I am also the first author or co-first author.

Download or read book 2D Materials written by Phaedon Avouris and published by Cambridge University Press. This book was released on 2017-06-29 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn about the most recent advances in 2D materials with this comprehensive and accessible text. Providing all the necessary materials science and physics background, leading experts discuss the fundamental properties of a wide range of 2D materials, and their potential applications in electronic, optoelectronic and photonic devices. Several important classes of materials are covered, from more established ones such as graphene, hexagonal boron nitride, and transition metal dichalcogenides, to new and emerging materials such as black phosphorus, silicene, and germanene. Readers will gain an in-depth understanding of the electronic structure and optical, thermal, mechanical, vibrational, spin and plasmonic properties of each material, as well as the different techniques that can be used for their synthesis. Presenting a unified perspective on 2D materials, this is an excellent resource for graduate students, researchers and practitioners working in nanotechnology, nanoelectronics, nanophotonics, condensed matter physics, and chemistry.

Download or read book SYMMETRY ENABLED DISCOVERY OF QUANTUM DEFECTS IN TWO DIMENSIONAL MATERIALS written by Jeng-Yuan Tsai and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum revolution has a great potential to impose massive impact on information technology. Point defects in solid-state materials such as NV center in diamond have been demonstrated to be promising qubit candidates. Defect levels in band gaps are analogous to molecular orbitals, serving as an excellent platform for quantum applications. Atomically thin two-dimensional materials are under the spotlight in recent years, as the sheet-like geometry brings advantages for operations of quantum defects. That includes the realization of patterned qubit fabrication, operation at room temperature, and improvement of coherence time through a highly-efficient isotope purification process. Although using point defects in 2D materials is a promising route toward quantum applications, searching for viable defects satisfying the criteria of magneto-optical properties for quantum applications is challenging. Thanks to the continued development of density functional theory, sophisticated multi-electron systems can be accurately simulated on the atomistic level to evaluate multiple ground-state properties, including total energy, magnetic polarization, and atomic orbitals. In addition to that, implementing constrained DFT renders the insight of excited-state properties. Benefited from the application of data-science tools in material science, we are now capable of performing data-driven analysis based on high-throughput computational techniques, including data mining/storage and automatic discovery workflow. Adopting the above tools and physical-principle-enabled symmetry analysis, we are able to identify a large set of quantum defects in a vast material space. We show that antisite defects in 2D transition metal dichalcogenides (TMDs) can provide a general platform for controllable solid-state spin qubit systems. Using high-throughput atomistic simulations that are enabled by a symmetry-based hypothesis, we identify several neutral antisite defects in TMDs that create defect levels deep in the bulk band gaps and host a paramagnetic triplet ground state. Our in-depth analysis reveals the presence of optical transitions and triplet-singlet intersystem crossing processes for fingerprinting these defect qubits. Finally, as an illustrative example, we discuss the initialization and readout principles of an antisite qubit in WS2, which is expected to be stable against interlayer interactions in a multilayer structure for qubit isolation and protection in future qubit-based devices. Motivated by the insight gained from the study of antisite defect qubits in TMDs, we significantly expanded the searching domain to all the binary 2D materials. As mentioned above, searching for defects with triplet ground states is one of the most crucial steps to identify more quantum defects that support multiple quantum functionalities. We design a comprehensive workflow for screening promising quantum defects based on the site-symmetry-based hypothesis. The discovery efforts reveal that the symmetry-enabled discovery workflow of quantum defects significantly increases the probability of finding triplet defects. To identify multiple functionalities for these quantum defects, including qubits and quantum emitters, the magneto-optical properties of triplet defects are comprehensively calculated. We demonstrate that 45 antisite defects in the various hosts, including post-transition metal monochalcogenides (PTMCs) and transition metal dichalcogenides (TMDs) are promising quantum defects. Most importantly, we propose that 16 antisites (both anion and cation based) in PTMCs can serve as the most promising quantum defect platform based on 2D materials, due to their well-defined defect levels, optimal magneto-optical properties, and the availability of host materials. This set of data-driven discovery efforts opens a new pathway for creating scalable, room-temperature spin qubits in 2D materials, including TMDs, PTMCs, and beyond. The comprehensive defect data created in this work, combined with experimental verification and demonstration in the future, will eventually lead to the fertilization of a 2D defect design platform that facilitates the design of point defects in 2D material families for multiple quantum functionalities, including quantum emitters, quantum sensor, transductor, and more.

Download or read book Crystallography and Crystal Chemistry of Materials with Layered Structures written by F.A. Lévy and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.