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Author: Cameron Foss Publisher: ISBN: Category : Languages : en Pages :
Book Description
A typical electronic or photonic device may consist of several materials each one potentially meeting at an interface or terminating with a free-surface boundary. As modern device dimensions reach deeper into the nanoscale regime, interfaces and boundaries become increasingly influential to both electrical and thermal energy transport. While a large majority of the device community focuses on the former, we focus here on the latter issue of thermal transport which is of great importance in implementing nanoscale devices as well as developing solutions for on-chip heat removal and waste heat scavenging. In this document we will discuss how modern performance enhancing techniques (strain, nanostructuring, alloying, etc.) affect thermal transport at boundaries and across interfaces through the avenue of three case studies. We use first-principles Density Functional Perturbation Theory to obtain the phonon spectrum of the materials of interest and then use the dispersion data as input to a phonon Boltzmann Transport model. First, we investigate the combined effects of strain and boundary scattering on the in-plane and cross-plane thermal conductivity of thin-film silicon and germanium. Second, we review a recently developed model for cross-dimensional (2D-3D) phonon transport and apply it to 3D-2D-3D stacked interfaces involving graphene and molybdenum disulfide 2D-layers. Third, we combine relevant models from earlier Chapters to study extrinsic effects, such as line edge roughness and substrate effects, on in-plane and through-plane thermal transport in 1H-phase transition metal dichalcogenide (TMD) alloys. Through these investigations we show that: (1) biaxial strain in Si and Ge thin-films can modulate cross-plane conductivity due to strong boundary scattering, (2) the thermal boundary conductance between 2D-3D materials can be enhanced in the presence of an encapsulating layer, and (3) the thermal conductivity of 1H-phase TMDs can be reduced by an order of magnitude through the combination of nanostructuring, alloying, and substrate effects.
Author: Cameron Foss Publisher: ISBN: Category : Languages : en Pages :
Book Description
A typical electronic or photonic device may consist of several materials each one potentially meeting at an interface or terminating with a free-surface boundary. As modern device dimensions reach deeper into the nanoscale regime, interfaces and boundaries become increasingly influential to both electrical and thermal energy transport. While a large majority of the device community focuses on the former, we focus here on the latter issue of thermal transport which is of great importance in implementing nanoscale devices as well as developing solutions for on-chip heat removal and waste heat scavenging. In this document we will discuss how modern performance enhancing techniques (strain, nanostructuring, alloying, etc.) affect thermal transport at boundaries and across interfaces through the avenue of three case studies. We use first-principles Density Functional Perturbation Theory to obtain the phonon spectrum of the materials of interest and then use the dispersion data as input to a phonon Boltzmann Transport model. First, we investigate the combined effects of strain and boundary scattering on the in-plane and cross-plane thermal conductivity of thin-film silicon and germanium. Second, we review a recently developed model for cross-dimensional (2D-3D) phonon transport and apply it to 3D-2D-3D stacked interfaces involving graphene and molybdenum disulfide 2D-layers. Third, we combine relevant models from earlier Chapters to study extrinsic effects, such as line edge roughness and substrate effects, on in-plane and through-plane thermal transport in 1H-phase transition metal dichalcogenide (TMD) alloys. Through these investigations we show that: (1) biaxial strain in Si and Ge thin-films can modulate cross-plane conductivity due to strong boundary scattering, (2) the thermal boundary conductance between 2D-3D materials can be enhanced in the presence of an encapsulating layer, and (3) the thermal conductivity of 1H-phase TMDs can be reduced by an order of magnitude through the combination of nanostructuring, alloying, and substrate effects.
Author: Carlos Manuel Da Silva Leal Publisher: ISBN: Category : Languages : en Pages :
Book Description
Over the last decade, substantial attention has been paid to novel nanostructures based on two-dimensional (2D) materials. Among the hundreds of 2D materials that have been successfully synthesized in recent years, graphene, boron nitride, and molybdenum disulfide are the ones that have been intensively studied. It has been demonstrated that these materials exhibit thermal conductivities significantly higher than those of bulk samples of the same material. However, little is known about the physics of phonons in these materials, especially when tensile strain is applied. Properties of these materials are still not well understood, and modelling approaches are still needed to support engineering design of these novel nanostructures. In this thesis, I use state-of-the-art atomistic simulation techniques in combination with statistical thermodynamics formulations to obtain the phonon properties (lifetime, group velocity, and heat capacity) and thermal conductivities of unstrained and strained samples of graphene, boron nitride, molybdenum disulfide, and also superlattices of graphene and boron nitride. Special emphasis is given to the role of the acoustic phonon modes and the thermal response of these materials to the application of tensile strain. I apply spectral analysis to a set of molecular dynamics trajectories to estimate phonon lifetimes, harmonic lattice dynamics to estimate phonon group velocities, and Bose-Einstein statistics to estimate phonon heat capacities. These phonon properties are used to predict the thermal conductivity by means of a mode-dependent equation from kinetic theory. In the superlattices, I study the variation of the frequency dependence of the phonon properties with the periodicity and interface configuration (zigzag and armchair) for superlattices with period lengths within the coherent regime. The results showed that the thermal conductivity decreases significantly from the shortest period length to the second period length, 13% across the interfaces and 16% along the interfaces. For greater periods, the conductivity across the interfaces continues decreasing at a smaller rate of 11 W/mK per period length increase, driven by changes in the phonon group velocities (coherent effects). In contrast, the conductivity along the interfaces slightly recovers at a rate of 2 W/mK per period, driven by changes in the phonon relaxation times (diffusive effects).
Author: Changzheng Wu Publisher: Royal Society of Chemistry ISBN: 1782624651 Category : Science Languages : en Pages : 428
Book Description
Inorganic Two-Dimensional Nanomaterials provides an overview of the development on inorganic two-dimensional nanomaterials from computational simulation and theoretical understanding to applications in energy conversion and storage.
Author: Pramoda Kumar Nayak Publisher: BoD – Books on Demand ISBN: 9535125540 Category : Technology & Engineering Languages : en Pages : 282
Book Description
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.
Author: Yongqing Cai Publisher: CRC Press ISBN: 1351358340 Category : Science Languages : en Pages : 293
Book Description
This book is the first attempt to systematically present the knowledge and research progress of phosphorene, another elemental 2D material that can be exfoliated by mechanical or liquid methods as the intensively studied graphene. The book provides a comprehensive overview of the synthesis, growth, characterization, and applications of phosphorene. It also compiles cutting-edge research in the related field with respect to thermal conduction, transistors, and electrochemical applications and encompasses the intrinsic properties (structural, electronic, defective, and phononic) of phosphorene. This book provides detailed mechanisms of phenomena observed for phosphorene. It will benefit graduate students of physics, chemistry, electrical and electronics engineering, and materials science and engineering; researchers in nanoscience working on phosphorene and similar 2D materials; and engineers and anyone involved in nanotechnology, nanoelectronics, materials preparation, and device fabrication based on layered materials.
Author: Anthony V Powell Publisher: Royal Society of Chemistry ISBN: 1788019601 Category : Science Languages : en Pages : 256
Book Description
Thermoelectric devices convert a heat flux directly into electrical power. They afford opportunities to achieve efficiency savings in a variety of applications, through the conversion of otherwise waste heat into useful electrical energy. Operated in reverse mode, they provide effective thermal management in areas ranging from cooling of electronic components to battery conditioning in electric vehicles. Implementation of thermoelectric technology requires materials with improved performance and stability, containing readily-available and inexpensive elements. A range of thermoelectric materials for use in different temperature regimes has emerged. Knowledge of the complex relationship between composition, structure and physical properties is central to understanding the performance of these advanced materials. This book provides both an introduction to the field of thermoelectrics and a survey of the state-of-the-art. Chapters review the important new families of advanced materials that have emerged and taken the field beyond traditional thermoelectric materials such as Bi2Te3, PbTe and SiGe. The emphasis is on the relationship between chemical composition, structure over a range of length scales and the physical properties that underlie performance. Edited by a leader in the field, and with contributions from global experts, Inorganic Thermoelectric Materials serves as an introduction to thermoelectric materials and is accessible to advanced undergraduates and postgraduates, as well as experienced researchers
Author: Armin Taheri Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The main objective of this thesis is to study phonon thermal transport in two-dimensional (2D) materials using first-principles density functional theory (DFT) calculations and the full solution of the Boltzmann transport equation (BTE). A wide range of 2D materials including graphene, 2D structures of group-VA, and recently emerged NX (X=P, As, Sb) compound monolayers are considered. Special attention is given to a mode-by-mode study of the thermal tunability via strain and functionalization. First, this thesis investigated the sensitivity of the DFT-calculated intrinsic thermal conductivity and phonon properties of 2D materials to the choice of exchange-correlation (XC) and pseudopotential (PP). It was found that the choice of the XC-PP combination results in significant discrepancies among predicted thermal conductivities of graphene at room temperature, in the range of 5442-8677 Wm^(-1)K^(-1). The LDA-NC and PBE-PAW combinations predicted the thermal conductivities in best agreement with available experimental data. This sensitivity analysis was an essential first step towards using DFT to engineer the phonon thermal transport in 2D systems. Next, DFT was used to systematically investigate the strain-dependent lattice thermal conductivity of -arsenene and -phosphorene, 2D monolayers of group-VA. The results showed that the thermal conductivity in both monolayers exhibits an up-and-down behavior when biaxial tensile strain is applied in the range from 0% to 9%. An interplay between phonon group velocities, heat capacities, and relaxation times, is found to be responsible for this behaviour. Finally, this project investigated the thermal conductivity of nitrogen functionalized - NX (X=P, As, Sb) monolayers. The results showed that the room-temperature thermal conductivities of -NP, -NAs, and -NSb are about 1.1, 5.5, and 34.0 times higher than those of their single-element -P, -As, and -Sb monolayers, respectively. The phonon transport analysis revealed that higher phonon group velocities, as well as higher phonon lifetimes were responsible for such an enhancement in the thermal conductivities of - NX compounds compared to single-element group-VA monolayers. Also, it was found that -NP has the minimum thermal conductivity among -NX monolayers, while it has the minimum average atomic mass. This thesis provides valuable insight into phonon physics and thermal transport in novel 2D materials using advanced DFT calculations.
Author: Frank Kreith Publisher: Springer Science & Business Media ISBN: 9783540663492 Category : Technology & Engineering Languages : en Pages : 1214
Book Description
This book is unique in its in-depth coverage of heat transfer and fluid mechanics including numerical and computer methods, applications, thermodynamics and fluid mechanics. It will serve as a comprehensive resource for professional engineers well into the new millennium. Some of the material will be drawn from the "Handbook of Mechanical Engineering," but with expanded information in such areas as compressible flow and pumps, conduction, and desalination.
Author: Vasilios N. Stavrou Publisher: BoD – Books on Demand ISBN: 1789846269 Category : Science Languages : en Pages : 176
Book Description
The field of low-dimensional structures has been experiencing rapid development in both theoretical and experimental research. Phonons in Low Dimensional Structures is a collection of chapters related to the properties of solid-state structures dependent on lattice vibrations. The book is divided into two parts. In the first part, research topics such as interface phonons and polaron states, carrier-phonon non-equilibrium dynamics, directional projection of elastic waves in parallel array of N elastically coupled waveguides, collective dynamics for longitudinal and transverse phonon modes, and elastic properties for bulk metallic glasses are related to semiconductor devices and metallic glasses devices. The second part of the book contains, among others, topics related to superconductor, phononic crystal carbon nanotube devices such as phonon dispersion calculations using density functional theory for a range of superconducting materials, phononic crystal-based MEMS resonators, absorption of acoustic phonons in the hyper-sound regime in fluorine-modified carbon nanotubes and single-walled nanotubes, phonon transport in carbon nanotubes, quantization of phonon thermal conductance, and phonon Anderson localization.
Author: Gyaneshwar P. Srivastava Publisher: CRC Press ISBN: 1000686922 Category : Science Languages : en Pages : 457
Book Description
This fully updated second edition of The Physics of Phonons remains the most comprehensive theoretical discussion devoted to the study of phonons, a major area of condensed matter physics. It contains exciting new sections on phonon-related properties of solid surfaces, atomically thin materials (such as graphene and monolayer transition metal chalcogenides), in addition to nano- structures and nanocomposites, thermoelectric nanomaterials, and topological nanomaterials, with an entirely new chapter dedicated to topological nanophononics and chiralphononics. Although primarily theoretical in approach, the author refers to experimental results wherever possible, ensuring an ideal book for both experimental and theoretical researchers. The author begins with an introduction to crystal symmetry and continues with a discussion of lattice dynamics in the harmonic approximation, including the traditional phenomenological approach and the more recent ab initio approach, detailed for the first time in this book. A discussion of anharmonicity is followed by the theory of lattice thermal conductivity, presented at a level far beyond that available in any other book. The chapter on phonon interactions is likewise more comprehensive than any similar discussion elsewhere. The sections on phonons in superlattices, impure and mixed crystals, quasicrystals, phonon spectroscopy, Kapitza resistance, and quantum evaporation also contain material appearing in book form for the first time. The book is complemented by numerous diagrams that aid understanding and is comprehensively referenced for further study. With its unprecedented wide coverage of the field, The Physics of Phonons is an indispensable guide for advanced undergraduates, postgraduates, and researchers working in condensed matter physics and materials science. Features Fully updated throughout, with exciting new coverage on graphene, nanostructures and nanocomposites, thermoelectric nanomaterials, and topological nanomaterials. Authored by an authority on phonons. Interdisciplinary, with broad applications through condensed matter physics, nanoscience, and materials science. --
Author: Cameron Foss
Author: Cameron Foss
Author: Carlos Manuel Da Silva Leal
Author: Changzheng Wu
Author: Pramoda Kumar Nayak
Author: Yongqing Cai
Author: Anthony V Powell
Author: Armin Taheri
Author: Frank Kreith
Author: Vasilios N. Stavrou
Author: Gyaneshwar P. Srivastava