Phonon Dynamics of Exotic Materials Bi2Se3, Bi2Te3, Sb2Te3 and WSe2 PDF Download
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Author: Kolawole Akintola Publisher: ISBN: Category : Languages : en Pages :
Book Description
Raman and Brillouin spectroscopy have been employed to investigate the phonon dynamics of Bi2Se3, Bi2Te3, Sb2Te3 (all topological insulators) and WSe2 (a 2D semiconductor). In the frequency range studied, two peaks were observed in the Raman spectra of Bi2Se3, Bi2Te3, Sb2Te3. Polarization studies were done to study the nature of these peaks and assign them to particular vibrational modes. Due to the fact that all three materials belong to the same space group and have the same Wycko↵ positions, it stands to reason that their Raman spectra will be identical in every respect except for the position where the peaks appear. This was found only to be partially true from what we observed. The presence of Te atoms in Bi2Te3, and Sb2Te3 was observed to play a prominent role in determining mode intensity. We verified that the higher intensity of the peak observed due to the A1g(2) 1g mode compared to that due to the Eg(2) g mode in Bi2Te3, and Sb2Te3, is most probably due some resonance effect induced by the laser excitation wavelength used. Raman scattering studies of WSe2 have generated much controversy with regards mode assignment and the shifts at with spectral peaks appear while there are no reports from Brillouin scattering studies of this material. Our Raman experiment shows that the Raman active E2g(1) 2g and A1g modes in WSe2 initially thought to be degenerate are not degenerate. This was verified by collecting spectra at different polarization configurations. One of the polarization configurations showed two closely separated peaks, enabling us to identify the constituent modes from the originally near-degenerate mode in the unpolarized spectrum. The velocity of the Rayleigh surface wave was extracted from the Brillouin spectra collected at different angles of incidence ranging from 35 to 80 degrees in a Brillouin light scattering experiment. The value of the velocity compares well with those previously reported for related materials. This work reports new results on the vibrational properties of Bi2Se3, Bi2Te3, Sb2Te3 and WSe2. Our results also resolves the inconsistencies reported in previous studies on the vibrational properties of these materials.
Author: Kolawole Akintola Publisher: ISBN: Category : Languages : en Pages :
Book Description
Raman and Brillouin spectroscopy have been employed to investigate the phonon dynamics of Bi2Se3, Bi2Te3, Sb2Te3 (all topological insulators) and WSe2 (a 2D semiconductor). In the frequency range studied, two peaks were observed in the Raman spectra of Bi2Se3, Bi2Te3, Sb2Te3. Polarization studies were done to study the nature of these peaks and assign them to particular vibrational modes. Due to the fact that all three materials belong to the same space group and have the same Wycko↵ positions, it stands to reason that their Raman spectra will be identical in every respect except for the position where the peaks appear. This was found only to be partially true from what we observed. The presence of Te atoms in Bi2Te3, and Sb2Te3 was observed to play a prominent role in determining mode intensity. We verified that the higher intensity of the peak observed due to the A1g(2) 1g mode compared to that due to the Eg(2) g mode in Bi2Te3, and Sb2Te3, is most probably due some resonance effect induced by the laser excitation wavelength used. Raman scattering studies of WSe2 have generated much controversy with regards mode assignment and the shifts at with spectral peaks appear while there are no reports from Brillouin scattering studies of this material. Our Raman experiment shows that the Raman active E2g(1) 2g and A1g modes in WSe2 initially thought to be degenerate are not degenerate. This was verified by collecting spectra at different polarization configurations. One of the polarization configurations showed two closely separated peaks, enabling us to identify the constituent modes from the originally near-degenerate mode in the unpolarized spectrum. The velocity of the Rayleigh surface wave was extracted from the Brillouin spectra collected at different angles of incidence ranging from 35 to 80 degrees in a Brillouin light scattering experiment. The value of the velocity compares well with those previously reported for related materials. This work reports new results on the vibrational properties of Bi2Se3, Bi2Te3, Sb2Te3 and WSe2. Our results also resolves the inconsistencies reported in previous studies on the vibrational properties of these materials.
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: A. Miller Publisher: CRC Press ISBN: 0429524935 Category : Science Languages : en Pages : 325
Book Description
Ultrafast photonics has become an interdisciplinary topic of high international research interest because of the spectacular development of compact and efficient lasers producing optical pulses with durations in the femtosecond time domain. Present day long-haul telecommunications systems are almost entirely based on the transmission of short burst
Author: Huixia Luo Publisher: John Wiley & Sons ISBN: 111940732X Category : Technology & Engineering Languages : en Pages : 420
Book Description
This book is the first pedagogical synthesis of the field of topological insulators and superconductors, one of the most exciting areas of research in condensed matter physics. Presenting the latest developments, while providing all the calculations necessary for a self-contained and complete description of the discipline, it is ideal for researchers and graduate students preparing to work in this area, and it will be an essential reference both within and outside the classroom. The book begins with the fundamental description on the topological phases of matter such as one, two- and three-dimensional topological insulators, and methods and tools for topological material's investigations, topological insulators for advanced optoelectronic devices, topological superconductors, saturable absorber and in plasmonic devices. Advanced Topological Insulators provides researchers and graduate students with the physical understanding and mathematical tools needed to embark on research in this rapidly evolving field.
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: Kunihito Koumoto Publisher: Springer Science & Business Media ISBN: 3642375375 Category : Technology & Engineering Languages : en Pages : 395
Book Description
Presently, there is an intense race throughout the world to develop good enough thermoelectric materials which can be used in wide scale applications. This book focuses comprehensively on very recent up-to-date breakthroughs in thermoelectrics utilizing nanomaterials and methods based in nanoscience. Importantly, it provides the readers with methodology and concepts utilizing atomic scale and nanoscale materials design (such as superlattice structuring, atomic network structuring and properties control, electron correlation design, low dimensionality, nanostructuring, etc.). Furthermore, also indicates the applications of thermoelectrics expected for the large emerging energy market. This book has a wide appeal and application value for anyone being interested in state-of-the-art thermoelectrics and/or actual viable applications in nanotechnology.
Author: Zongyu Huang Publisher: CRC Press ISBN: 1000562840 Category : Science Languages : en Pages : 166
Book Description
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: Stepan S. Batsanov Publisher: Springer Science & Business Media ISBN: 9400747713 Category : Medical Languages : en Pages : 548
Book Description
A concise description of models and quantitative parameters in structural chemistry and their interrelations, with 280 tables and >3000 references giving the most up-to-date experimental data on energy characteristics of atoms, molecules and crystals (ionisation potentials, electron affinities, bond energies, heats of phase transitions, band and lattice energies), optical properties (refractive index, polarisability), spectroscopic characteristics and geometrical parameters (bond distances and angles, coordination numbers) of substances in gaseous, liquid and solid states, in glasses and melts, for various thermodynamic conditions. Systems of metallic, covalent, ionic and van der Waals radii, effective atomic charges and other empirical and semi-empirical models are critically revised. Special attention is given to new and growing areas: structural studies of solids under high pressures and van der Waals molecules in gases. The book is addressed to researchers, academics, postgraduates and advanced-course students in crystallography, materials science, physical chemistry of solids.
Author: Loutfy H. Madkour Publisher: Springer ISBN: 3030216217 Category : Technology & Engineering Languages : en Pages : 814
Book Description
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?
Author: Kolawole Akintola
Author: Kolawole Akintola
Author: Alexander V. Kolobov
Author: A. Miller
Author: Huixia Luo
Author: Narayanasamy Sabari Arul
Author: Kunihito Koumoto
Author: Zongyu Huang
Author: Stepan S. Batsanov
Author: Loutfy H. Madkour
Author: