Download or read book Micro and Nano optical Spectroscopy Investigation of 2D Transition Metal Dichalcogenides TMDCs written by Yang Pan and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 Probing Quantized Excitations and Many body Correlations in Transition Metal Dichalcogenides with Optical Spectroscopy written by Shao-Yu Chen and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Layered transition metal dichalcogenides (TMDCs) have attracted great interests in recent years due to their physical properties manifested in different polytypes: Hexagonal(H)-TMDC,which is semiconducting, exhibits strong Coulomb interaction and intriguing valleytronic properties; distorted octahedral(T')-TMDC,which is semi-metallic, is predicted to exhibit rich nontrivial topological physics. In this dissertation,we employ the polarization-resolved micron-Raman/PL spectroscopy to investigate the optical properties of the atomic layer of several polytypes of TMDC. In the first part for polarization-resolved Raman spectroscopy, we study the lattice vibration of both H and T'-TMDC, providing a thorough understanding of the polymorphism of TMDCs. We demonstrate that Raman spectroscopy is a versatile tool to probe the symmetry as well as the quality of crystals. This becomes quite important for atomic layers of TMDCs which are sensitive to the environment and substrate. In the second part of the dissertation, we focus on fabricating high-quality monolayer tungsten diselenide samples and study their excitonic bound states by photoluminescence, reflection, resonant-Raman spectroscopy, magneto-optical measurements, and time-resolved spectroscopy. We first demonstrate the many-body correlation of the multi-particle bound excitonic states at low temperatures. The PL measurements in magnetic fields demonstrate for the first time the abnormal valleytronic properties of the biexciton and five-particle bound states, exciton-trion in 1L-TMDCs. The time-resolved PL measurement reveals the ultralong lifetime of the several bound states at even lower energy range, establishing a potential platform for further investigation on exciton condensation. In addition to the lower energy bound states, we also explore its excited Rydberg states in high magnetic fields. Surprisingly, we observe for the first time the PL of up to 4s excitons, opening doors to the investigation the physics of Rydberg exciton in a 2D system. For example, we investigate the role of electron-hole exchange-interactions in 2s exciton. Contrary to 1s exciton, the exchange interaction in 2s exciton is strongly suppressed due to its larger size. Consequently, the 2s exciton display superior valley polarization and valley coherence, paving the way to valleytronic applications.

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 SYNTHESIS CHARACTERIZATION AND APPLICATION OF 2D TRANSITION METAL DICHALCOGENIDES written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : The rapid development of two-dimensional (2D) materials has led to tremendous interest in the study of graphene and a series of mono- and few-layered transition metal dichalcogenides (TMDCs). One major attraction of TMDCs is their semiconducting nature with indirect to direct bandgap transition, when thinned from bulk to few- and mono- layers. Molybdenum disulfide (MoS2) is one of the 2D TMDCs that has gained increasing attention due to its promising optical, electronic, and optoelectronic properties. In this thesis, I will discuss my research on the synthesis of 2D MoS2 and the characterization of its optical properties by Raman, Photoluminescence (PL) and UV-Vis spectroscopy. Next, the application of 2D TMDCs for FETs and solar cells will be reviewed. Finally, my extended work on the oxide form (transition metal oxides) and zero-dimensional (0D) form of TMDCs will be discussed. Efficient solar cells constructed by MoO3 and other oxides, and the future application of 0D TMDCs will also be evaluated.

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 Investigation of Two Dimensional Transition Metal Dichalcogenides by Optical and Scanning Tunneling Spectroscopy written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The latter portion of this dissertation will cover the nanoscopic dynamics of TMDC heterostructures. The Kramers-Kronig relations will be derived and discussed in detail. Data and results regarding the electronic structure of these materials, their heterostructures, and their custom alloys measured via scanning tunneling microscopy will be presented. Coupled with the measured optical properties, significant numerical quantities that characterize these materials are extracted. There will be several appendices that offer some supplementary information and basic summaries about all the projects that were initiated.

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 Semiconductors written by Martin I. Pech-Canul and published by Springer. This book was released on 2019-01-17 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a practical guide to optical, optoelectronic, and semiconductor materials and provides an overview of the topic from its fundamentals to cutting-edge processing routes to groundbreaking technologies for the most recent applications. The book details the characterization and properties of these materials. Chemical methods of synthesis are emphasized by the authors throughout the publication. Describes new materials and updates to older materials that exhibit optical, optoelectronic and semiconductor behaviors; Covers the structural and mechanical aspects of the optical, optoelectronic and semiconductor materials for meeting mechanical property and safety requirements; Includes discussion of the environmental and sustainability issues regarding optical, optoelectronic, and semiconductor materials, from processing to recycling.

Download or read book 2D Materials for Nanoelectronics written by Michel Houssa and published by CRC Press. This book was released on 2016-05-05 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Major developments in the semiconductor industry are on the horizon through the use of two-dimensional (2D) materials, such as graphene and transition metal dichalcogenides, for integrated circuits (ICs). 2D Materials for Nanoelectronics is the first comprehensive treatment of these materials and their applications in nanoelectronic devices.Compris

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 Optical Study on Two Dimensional Transition Metal Dichalcogenides written by Bairen Zhu and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Optical Study on Two Dimensional Transition Metal Dichalcogenides" by Bairen, Zhu, 朱柏仁, 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: Atomically thin group-VI transition metal dichalcogenides (TMDC) has been emerging as a family of intrinsic 2-dimensional (2D) crystals with a sizeable bandgap in the visible and near infrared range, satisfying numerous requirements for ultimate electronics and optoelectronics. This intrinsic 2D crystal also provides a perfect platform for physics study in 2D semiconductors. The characteristic inversion symmetry breaking presented in monolayer TMDCs leads to non-zero but contrasting Berry curvatures and orbital magnetic moments at K/K' valleys located at the corners of the first Brillouin zone. These features provide an opportunity to manipulate electrons' additional internal degrees of freedom, namely the valley degree of freedom, making monolayer TMDC a promising candidate for the conceptual valleytronics. Besides, the strong spin-orbit interactions and the subsequent spin-valley coupling demonstrated in 2D TMDCs open potential new routes towards quantum manipulation. In this thesis, I give a brief review on the background and our progress of the physics study in 2D TMDCs (MoS2, WS2) via optical spectroscopy. Particularly, our experimental approach on the excitonic effect, valley dependent circular dichroism, and the spin-valley coupling in monolayer and bilayer TMDCs are elaborated in individual chapters. DOI: 10.5353/th_b5351031 Subjects: Transition metal compounds - Optical properties Chalcogenides - Optical properties

Download or read book Semiconductor Electrochemistry written by Rüdiger Memming and published by John Wiley & Sons. This book was released on 2015-06-22 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing both an introduction and an up-to-date survey of the entire field, this text captivates the reader with its clear style and inspiring, yet solid presentation. The significantly expanded second edition of this milestone work is supplemented by a completely new chapter on the hot topic of nanoparticles and includes the latest insights into the deposition of dye layers on semiconductor electrodes. In his monograph, the acknowledged expert Professor Memming primarily addresses physical and electrochemists, but materials scientists, physicists, and engineers dealing with semiconductor technology and its applications will also benefit greatly from the contents.

Download or read book Nanoelectronic Materials written by Loutfy H. Madkour and published by Springer. This book was released on 2019-06-27 with total page 814 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents synthesis techniques for the preparation of low-dimensional nanomaterials including 0D (quantum dots), 1D (nanowires, nanotubes) and 2D (thin films, few layers), as well as their potential applications in nanoelectronic systems. It focuses on the size effects involved in the transition from bulk materials to nanomaterials; the electronic properties of nanoscale devices; and different classes of nanomaterials from microelectronics to nanoelectronics, to molecular electronics. Furthermore, it demonstrates the structural stability, physical, chemical, magnetic, optical, electrical, thermal, electronic and mechanical properties of the nanomaterials. Subsequent chapters address their characterization, fabrication techniques from lab-scale to mass production, and functionality. In turn, the book considers the environmental impact of nanotechnology and novel applications in the mechanical industries, energy harvesting, clean energy, manufacturing materials, electronics, transistors, health and medical therapy. In closing, it addresses the combination of biological systems with nanoelectronics and highlights examples of nanoelectronic–cell interfaces and other advanced medical applications. The book answers the following questions: • What is different at the nanoscale? • What is new about nanoscience? • What are nanomaterials (NMs)? • What are the fundamental issues in nanomaterials? • Where are nanomaterials found? • What nanomaterials exist in nature? • What is the importance of NMs in our lives? • Why so much interest in nanomaterials? • What is at nanoscale in nanomaterials? • What is graphene? • Are pure low-dimensional systems interesting and worth pursuing? • Are nanotechnology products currently available? • What are sensors? • How can Artificial Intelligence (AI) and nanotechnology work together? • What are the recent advances in nanoelectronic materials? • What are the latest applications of NMs?

Download or read book Optical Study on Two Dimensional Transition Metal Dichalcogenides written by 朱柏仁 and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book SPIN AND VALLEY DEPENDENT EXCITONS IN ATOMICALLY THIN TRANSITION METAL DICHALCOGENIDES written by Zefang Wang and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal dichalcogenides (TMDCs) exhibit remarkable electronic properties when thinned down to the monolayer limit. Among them, atomically thin semiconducting TMDCs, such as MoS2, MoSe2, WSe2, etc., attract board interest due to their unique electronic and optoelectronic properties. Electrons in 2D TMDCs acquire not only spin but also valley degree of freedom, and the spin and valley are coupled due to broken inversion symmetry and strong spin-orbit coupling. Opposite valleys are associated with opposite Berry curvature, giving rise to interesting valley physics and valleytronic applications. Another unique aspect of atomically thin TMDCs is strong excitonic effect. Owing to quantum confinement, monolayer semiconducting TMDCs become direct bandgap semiconductor in contrast to indirect bandgap in their bulk counterparts, and the excitonic effect gets greatly boosted due to the reduced dimensionality. Strong excitonic effect gives rise to strong light-matter interaction, making optical spectroscopy a powerful tool to access intriguing spin and valley properties of 2D TMDCs.In this dissertation, we explore the spin and valley dependent properties of monolayer TMDCs with optical and electrical transport techniques with high quality devices. In the first part, we study the electronic band structure in K/K valleys of Brillouin zone of monolayer WSe2 and MoSe2 by optical reflection and photoluminescence spectroscopy on dual gate field-effect transistors. Our experiment reveals the distinct spin polarization in the conduction band of these compounds by a systematic study of the doping dependence of A and B excitonic resonances. We obtained conduction band spin splitting delta_c is approximately 40meV for WSe2 and delta_c is approximately -30meV for MoSe2, which are in good agreements with first principle calculations.In the second part, we examined Landau level structure in monolayer WSe2 at the presence of out-of-plane magnetic field. It is proposed by theory that the Berry curvature in valley degree of freedom together with strong spin-orbit interaction can generate unconventional Landau levels under a perpendicular magnetic field. We applied handedness-resolved optical reflection spectroscopy and observed fully valley- and spin-polarized LLs in high quality WSe2 monolayer field-effect transistor and therefore derived LL structure. We also measured a sizeable doping-induced mass renormalization driven by strong Coulomb interactions.In the third part, we continued to explore the strong Coulomb interactions by studying the valley magnetic response in 2D TMDCs. We measured doping dependency of the valley Zeeman splitting of the charged exciton emission in monolayer WSe2 under an out-of-plane magnetic field. A nonlinear valley Zeeman effect correlated with an over fourfold enhancement in the g-factor, is observed. This enhancement occurs when Fermi level crosses the spin-split upper conduction band, corresponding to a change of spin-valley degeneracy from two to four, and can be understood as a consequence of a sharp increase in the exchange interaction when the number of electron species doubles. This interaction-enhanced valley magnetic response suggests 2D TMDCs as a new platform for exploring strongly interacting electron system with multiple internal degrees of freedom.In the final part, a study on interlayer exciton in bilayer WSe2 is presented. Interlayer excitons are sought for creating high exciton density and optoelectronic applications due to their long lifetime. Here we demonstrate highly tunable interlayer excitons by an out-of-plane electric field in bilayer WSe2. Continuous tuning of the exciton dipole from negative to positive orientation has been achieved and a large linear field-induced redshift up to ~100meV has been observed in exciton resonance energy. The Stark effect is accompanied by an enhancement of exciton lifetime by more than two orders of magnitude to >20ns. The exciton density as high as 1.210^11 cm^(2) can be created by moderate continuous-wave optical pumping. Our result has paved the way for realization of degenerate exciton gases in 2D TMDCs.