Exciton Dynamics in Van Der Waals Heterostructures PDF Download

Author: James Howarth
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Junho Choi
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Van der Waals (vdW) heterostructures represent a promising material platform with rich electronic and optical properties highly tunable via a wide selection of layer materials, electric doping, strain, and twist angle. Monolayers of transition metal dichalcogenide (TMD) semiconductors commonly show strong light-matter coupling and direct bandgaps from the infrared to the visible spectral range, making them promising candidates for various optoelectronic applications. Vertically stacking different TMD monolayers allows one to create TMD heterostructures with rich and tunable correlated electronic phases and optical properties. Among different methods to tune the properties of vdW heterostructures, the twist angle is the most unique parameter. In this dissertation, we investigated the twist angle dependent optical properties of interlayer excitons in TMD heterostructures. First, we studied the twist-angle dependent interlayer exciton lifetimes in MoSe2/WSe2 heterostructures. We found that the multiple resonances of interlayer excitons subject to strong confinement in the moiré potential. Their properties are consistent with the interpretation that these resonances are ground- and excited state excitons. Our experiments further revealed that the recombination dynamics of interlayer excitons depends strongly on the twist angle. For example, their lifetimes change from ~ 1 ns to hundreds of ns when the twist angle is increased from 1 to 3.5°. In collaboration with a theoretical group, we explored two mechanisms for this drastic dependence. First, a relative rotation between the two layers in real space translates to a rotation in the momentum space. As the twist angle is increased, the interlayer exciton transitions change from direct- to indirect transitions in the momentum spacing, leading to a longer lifetime. Second, the presence of moiré potential also has a significant impact on the lifetime, reducing its angle dependence by relaxing the requirement of momentum conservation. Next, we investigated the influence of moiré potential on interlayer exciton diffusion in MoSe2/WSe2 heterostructures. The interlayer exciton diffusion offers a unique channel of energy and information transport in TMD heterostructures. While early studies focused on how mobile excitons are in TMD heterostructures, we find that interlayer exciton diffusion is impeded in the presence of the moiré potential by comparing two types of samples: those prepared by mechanical exfoliation and those grown with chemical vapor deposition. We investigated multiple mechanically stacked samples with accurately controlled twist-angles. We showed that the interlayer exciton diffusion does not depend on the size of the moiré supercell in a simple and monotonic manner. These experiments provide an important and complementary view of the diffusion properties of interlayer excitons from those reported in the literature

Author: Miguel A.L. Marques
Publisher: Springer Science & Business Media
ISBN: 3642235182
Category : Science
Languages : en
Pages : 573

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There have been many significant advances in time-dependent density functional theory over recent years, both in enlightening the fundamental theoretical basis of the theory, as well as in computational algorithms and applications. This book, as successor to the highly successful volume Time-Dependent Density Functional Theory (Lect. Notes Phys. 706, 2006) brings together for the first time all recent developments in a systematic and coherent way. First, a thorough pedagogical presentation of the fundamental theory is given, clarifying aspects of the original proofs and theorems, as well as presenting fresh developments that extend the theory into new realms—such as alternative proofs of the original Runge-Gross theorem, open quantum systems, and dispersion forces to name but a few. Next, all of the basic concepts are introduced sequentially and building in complexity, eventually reaching the level of open problems of interest. Contemporary applications of the theory are discussed, from real-time coupled-electron-ion dynamics, to excited-state dynamics and molecular transport. Last but not least, the authors introduce and review recent advances in computational implementation, including massively parallel architectures and graphical processing units. Special care has been taken in editing this volume as a multi-author textbook, following a coherent line of thought, and making all the relevant connections between chapters and concepts consistent throughout. As such it will prove to be the text of reference in this field, both for beginners as well as expert researchers and lecturers teaching advanced quantum mechanical methods to model complex physical systems, from molecules to nanostructures, from biocomplexes to surfaces, solids and liquids. From the reviews of LNP 706: “This is a well structured text, with a common set of notations and a single comprehensive and up-to-date list of references, rather than just a compilation of research articles. Because of its clear organization, the book can be used by novices (basic knowledge of ground-state DFT is assumed) and experienced users of TD-DFT, as well as developers in the field.” (Anna I. Krylov, Journal of the American Chemical Society, Vol. 129 (21), 2007) “This book is a treasure of knowledge and I highly recommend it. Although it is a compilation of chapters written by many different leading researchers involved in development and application of TDDFT, the contributors have taken great care to make sure the book is pedagogically sound and the chapters complement each other [...]. It is highly accessible to any graduate student of chemistry or physics with a solid grounding in many-particle quantum mechanics, wishing to understand both the fundamental theory as well as the exponentially growing number of applications. [...] In any case, no matter what your background is, it is a must-read and an excellent reference to have on your shelf.” Amazon.com, October 15, 2008, David Tempel (Cambridge, MA)

Author: Hartmut Haug
Publisher: World Scientific
ISBN: 9789810218645
Category : Science
Languages : en
Pages : 496

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This textbook presents the basic elements needed to understand and engage in research in semiconductor physics. It deals with elementary excitations in bulk and low-dimensional semiconductors, including quantum wells, quantum wires and quantum dots. The basic principles underlying optical nonlinearities are developed, including excitonic and many-body plasma effects. The fundamentals of optical bistability, semiconductor lasers, femtosecond excitation, optical Stark effect, semiconductor photon echo, magneto-optic effects, as well as bulk and quantum-confined Franz-Keldysh effects are covered. The material is presented in sufficient detail for graduate students and researchers who have a general background in quantum mechanics.

Author: Zheng Zhang
Publisher: John Wiley & Sons
ISBN: 3527349502
Category : Technology & Engineering
Languages : en
Pages : 340

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Book Description
Van der Waals Heterostructures A comprehensive resource systematically detailing the developments and applications of van der Waals heterostructures and devices Van der Waals Heterostructures is essential reading to understand the developments made in van der Waals heterostructures and devices in all aspects, from basic synthesis to physical analysis and heterostructures assembling to devices applications, including demonstrated applications of van der Waals heterostructure on electronics, optoelectronics, and energy conversion, such as solar energy, hydrogen energy, batteries, catalysts, biotechnology, and more. This book starts from an in-depth introduction of van der Waals interactions in layered materials and the forming of mixed-dimensional heterostructures via van der Waals force. It then comprehensively summarizes the synthetic methods, devices building processes and physical mechanism of 2D van der Waals heterostructures, and devices including 2D-2D electronics, 2D-2D optoelectronics, and mixed dimensional van der Waals heterostructures. In Van der Waals Heterostructures, readers can expect to find specific information on: The current library of 2D semiconductors and the current synthesis and performances of 2D semiconductors Controllable synthesis and assemble van der Waals heterostructures, physics of the van der Waals interface, and multi-field coupling effects 2D-2D electronics, 2D-2D optoelectronics, mixed dimensional van der Waals heterostructures, and van der Waals heterostructure applications on energy conversion Insight into future perspectives of the van der Waals heterostructures and devices with the detailed effective role of 2D materials for integrated electrical and electronic equipment

Author: Kallol Roy
Publisher: Springer Nature
ISBN: 3030596273
Category : Technology & Engineering
Languages : en
Pages : 277

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This thesis deals with the development and in-depth study of a new class of optoelectronic material platform comprising graphene and MoS_2, in which MoS_2 is used essentially to sensitize graphene and lead to unprecedently high gain and novel opto-electronic memory effects. The results presented here open up the possibility of designing a new class of photosensitive devices which can be utilized in various optoelectronic applications including biomedical sensing, astronomical sensing, optical communications, optical quantum information processing and in applications requiring low intensity photodetection and number resolved single photon detection.

Author: Phaedon Avouris
Publisher: Cambridge University Press
ISBN: 1316738132
Category : Technology & Engineering
Languages : en
Pages : 521

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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.

Author: Zongyu Huang
Publisher: CRC Press
ISBN: 1000562840
Category : Science
Languages : en
Pages : 166

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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.

Author: Arash Rahimi-Iman
Publisher: Springer Nature
ISBN: 303069352X
Category : Science
Languages : en
Pages : 288

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Book Description
This book introduces the wider field of functional nanomaterials sciences, with a strong emphasis on semiconductor photonics. Whether you are studying photonic quantum devices or just interested in semiconductor nanomaterials and their benefits for optoelectronic applications, this book offers you a pedagogical overview of the relevant subjects along with topical reviews. The book discusses different yet complementary studies in the context of ongoing international research efforts, delivering examples from both fundamental and applied research to a broad readership. In addition, a hand-full of useful optical techniques for the characterization of semiconductor quantum structures and materials are addressed. Moreover, nanostructuring methods for the production of low-dimensional systems, which exhibit advantageous properties predominantly due to quantum effects, are summarized. Science and engineering professionals in the interdisciplinary domains of nanotechnology, photonics, materials sciences, and quantum physics can familiarize themselves with selected highlights with eyes towards photonic applications in the fields of two-dimensional materials research, light–matter interactions, and quantum technologies.

Author: Alexander V. Kolobov
Publisher: Springer
ISBN: 3319314505
Category : Technology & Engineering
Languages : en
Pages : 545

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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.