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Experimental Investigation Of Thermal Transport In Low Dimensional Nanomaterials
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Book Synopsis Experimental Investigation of Thermal Transport in Low-dimensional Nanomaterials by : Daniel Josephus Alpas Villaroman
Download or read book Experimental Investigation of Thermal Transport in Low-dimensional Nanomaterials written by Daniel Josephus Alpas Villaroman and published by . This book was released on 2017 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental Investigations of Thermal Transport in Carbon Nanotubes, Graphene and Nanoscale Point Contacts by : Michael Thompson Pettes
Download or read book Experimental Investigations of Thermal Transport in Carbon Nanotubes, Graphene and Nanoscale Point Contacts written by Michael Thompson Pettes and published by . This book was released on 2011 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: As silicon-based transistor technology continues to scale ever downward, anticipation of the fundamental limitations of ultimately-scaled devices has driven research into alternative device technologies as well as new materials for interconnects and packaging. Additionally, as power dissipation becomes an increasingly important challenge in highly miniaturized devices, both the implementation and verification of high mobility, high thermal conductivity materials, such as low dimensional carbon nanomaterials, and the experimental investigation of heat transfer in the nanoscale regime are requisite to continued progress. This work furthers the current understanding of structure-property relationships in low dimensional carbon nanomaterials, specifically carbon nanotubes (CNTs) and graphene, through use of combined thermal conductance and transmission electron microscopy (TEM) measurements on the same individual nanomaterials suspended between two micro-resistance thermometers. Through the development of a method to measure thermal contact resistance, the intrinsic thermal conductivity, [kappa], of multi-walled (MW) CNTs is found to correlate with TEM observed defect density, linking phonon-defect scattering to the low [kappa] in these chemical vapor deposition (CVD) synthesized nanomaterials. For single- (S) and double- (D) walled (W) CNTs, the [kappa] is found to be limited by thermal contact resistance for the as-grown samples but still four times higher than that for bulk Si. Additionally, through the use of a combined thermal transport-TEM study, the [kappa] of bi-layer graphene is correlated with both crystal structure and surface conditions. Theoretical modeling of the [kappa] temperature dependence allows for the determination that phonon scattering mechanisms in suspended bi-layer graphene with a thin polymeric coating are similar to those for the case of graphene supported on SiO2. Furthermore, a method is developed to investigate heat transfer through a nanoscale point contact formed between a sharp silicon tip and a silicon substrate in an ultra high vacuum (UHV) atomic force microscope (AFM). A contact mechanics model of the interface, combined with a heat transport model considering solid-solid conduction and near-field thermal radiation leads to the conclusion that the thermal resistance of the nanoscale point contact is dominated by solid-solid conduction.
Book Synopsis Phonon Thermal Transport in Silicon-Based Nanomaterials by : Hai-Peng Li
Download or read book Phonon Thermal Transport in Silicon-Based Nanomaterials written by Hai-Peng Li and published by Springer. This book was released on 2018-09-08 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this Brief, authors introduce the advance in theoretical and experimental techniques for determining the thermal conductivity in nanomaterials, and focus on review of their recent theoretical studies on the thermal properties of silicon–based nanomaterials, such as zero–dimensional silicon nanoclusters, one–dimensional silicon nanowires, and graphenelike two–dimensional silicene. The specific subject matters covered include: size effect of thermal stability and phonon thermal transport in spherical silicon nanoclusters, surface effects of phonon thermal transport in silicon nanowires, and defects effects of phonon thermal transport in silicene. The results obtained are supplemented by numerical calculations, presented as tables and figures. The potential applications of these findings in nanoelectrics and thermoelectric energy conversion are also discussed. In this regard, this Brief represents an authoritative, systematic, and detailed description of the current status of phonon thermal transport in silicon–based nanomaterials. This Brief should be a highly valuable reference for young scientists and postgraduate students active in the fields of nanoscale thermal transport and silicon-based nanomaterials.
Book Synopsis Nanoscale Energy Transport and Harvesting by : Zhang Gang
Download or read book Nanoscale Energy Transport and Harvesting written by Zhang Gang and published by CRC Press. This book was released on 2015-02-04 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Energy transport and conversion in nanoscale structures is a rapidly expanding area of science. It looks set to make a significant impact on human life and, with numerous commercial developments emerging, will become a major academic topic over the coming years. Owing to the difficulty in experimental measurement, computational simulation has becom
Book Synopsis Experimental Micro/Nanoscale Thermal Transport by : Xinwei Wang
Download or read book Experimental Micro/Nanoscale Thermal Transport written by Xinwei Wang and published by John Wiley & Sons. This book was released on 2012-05-09 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the new technologies on micro/nanoscale thermal characterization developed in the Micro/Nanoscale Thermal Science Laboratory led by Dr. Xinwei Wang. Five new non-contact and non-destructive technologies are introduced: optical heating and electrical sensing technique, transient electro-thermal technique, transient photo-electro-thermal technique, pulsed laser-assisted thermal relaxation technique, and steady-state electro-Raman-thermal technique. These techniques feature significantly improved ease of implementation, super signal-to-noise ratio, and have the capacity of measuring the thermal conductivity/diffusivity of various one-dimensional structures from dielectric, semiconductive, to metallic materials.
Book Synopsis Micro and Nano Thermal Transport by : Lin Qiu
Download or read book Micro and Nano Thermal Transport written by Lin Qiu and published by Academic Press. This book was released on 2022-02-09 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: Micro and Nano Thermal Transport Research: Characterization, Measurement and Mechanism is a complete and reliable reference on thermal measurement methods and mechanisms of micro and nanoscale materials. The book has a strong focus on applications and simulation, providing clear guidance on how to measure thermal properties in a systematic way. Sections cover the fundamentals of thermal properties before introducing tools to help readers identify and analyze thermal characteristics of these materials. The thermal transport properties are then further explored by means of simulation which reflect the internal mechanisms used to generate such thermal properties. Readers will gain a clear understanding of thermophysical measurement methods and the representative thermal transport characteristics of micro/nanoscale materials with different structures and are guided through a decision-making process to choose the most effective method to master thermal analysis. The book is particularly suitable for those engaged in the design and development of thermal property measurement instruments, as well as researchers of thermal transport at the micro and nanoscale. Includes a variety of measurement methods and thermal transport characteristics of micro and nanoscale materials under different structures Guides the reader through the decision-making process to ensure the best thermal analysis method is selected for their setting Contains experiments and simulations throughout that help apply understanding to practice
Book Synopsis Experimental and Theoretical Investigation of Thermal and Thermoelectric Transport in Nanostructures by : Arden Lot Moore
Download or read book Experimental and Theoretical Investigation of Thermal and Thermoelectric Transport in Nanostructures written by Arden Lot Moore and published by . This book was released on 2010 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents the development and application of analytical, numerical, and experimental methods for the study of thermal and electrical transport in nanoscale systems, with special emphasis on those materials and phenomena which can be important in thermoelectric and semiconductor device applications. Analytical solutions to the Boltzmann transport equation (BTE) using the relaxation time approximation (RTA) are presented and used to study the thermal and electrical transport properties of indium antimonide (InSb), indium arsenide (InAs), bismuth telluride (Bi2Te3), and chromium disilicide (CrSi2) nanowires. Experimental results for the thermal conductivity of single layer graphene supported by SiO2 were analyzed using an RTA-based model and compared to a full quantum mechanical numerical BTE solution which does not rely on the RTA. The ability of these models to explain the measurement results as well as differences between the two approaches are discussed. Alternatively, numerical solutions to the BTE may be obtained statistically through Monte Carlo simulation for complex geometries which may prove intractable for analytical methods. Following this approach, phonon transport in silicon (Si) sawtooth nanowires was studied, revealing that thermal conductivity suppression below the diffuse surface limit is possible. The experimental investigation of energy transport in nanostructures typically involved the use of microfabricated devices or non-contact optical methods. In this work, two such approaches were analyzed to ascertain their thermal behavior and overall accuracy as well as areas for possible improvement. A Raman spectroscopy-based measurement design for investigating the thermal properties of suspended and supported graphene was examined analytically. The resulting analysis provided a means of determining from measurement results the thermal interface conductance, thermal contact resistance, and thermal conductivity of the suspended and supported graphene regions. Previously, microfabricated devices of several different designs have been used to experimentally measure the thermal transport characteristics of nanostructures such as carbon nanotubes, nanowires, and thin films. To ascertain the accuracy and limitations of various microdevice designs and their associated conduction analyses, finite element models were constructed using ANSYS and measurements of samples of known thermal conductance were simulated. It was found that designs with the sample suspended were generally more accurate than those for which the sample is supported on a bridge whose conductance is measured separately. The effects of radiation loss to the environment of certain device designs were also studied, demonstrating the need for radiation shielding to be at temperatures close to that of the device substrate in order to accurately calibrate the resistance thermometers. Using a suspended microdevice like those analyzed using finite element analysis, the thermal conductivities of individual bismuth (Bi) nanowires were measured. The results were correlated with the crystal structure and growth direction obtained by transmission electron microscopy on the same nanowires. Compared to bulk Bi in the same crystal direction, the thermal conductivity of a single-crystal Bi nanowires of 232 nm diameter was found to be 3 - 6 times smaller than bulk between 100 K and 300 K. For polycrystalline Bi nanowires of 74 nm to 255 nm diameter the thermal conductivity was reduced by a factor of 18 - 78 over the same temperature range. Comparable thermal conductivity values were measured for polycrystalline nanowires of varying diameters, suggesting a grain boundary scattering mean free path for all heat carriers in the range of 15 - 40 nm which is smaller than the nanowire diameters. An RTA-based transport model for both charge carriers and phonons was developed which explains the thermal conductivity suppression in the single-crystal nanowire by considering diffuse phonon-surface scattering, partially diffuse surface scattering of electrons and holes, and scattering of phonons and charge carriers by ionized impurities such as oxygen and carbon of a concentration on the order of 1019 cm−3. Using a similar experimental setup, the thermoelectric properties (Seebeck coefficient, electrical conductivity, and thermal conductivity) of higher manganese silicide (HMS) nanostructures were investigated. Bulk HMS is a passable high temperature thermoelectric material which possesses a complex crystal structure that could lead to very interesting and useful nanoscale transport properties. The thermal conductivities of HMS nanowires and nanoribbons were found to be reduced by 50 - 60 % compared to bulk values in the same crystal direction for both nanoribbons and nanowires. The measured Seebeck coefficient data was comparable or below that of bulk, suggesting unintentional doping of the samples either during growth or sample preparation. Difficulty in determining the amorphous oxide layer thickness for nanoribbons samples necessitated using the total, oxide-included cross section in the thermal and electrical conductivity calculation. This in turn led to the determined electrical conductivity values representing the lower bound on the actual electrical conductivity of the HMS core. From this approach, the measured electrical conductivity values were comparable or slightly below the lower end of bulk electrical conductivity values. This oxide thickness issue affects the determination of the HMS nanostructure thermoelectric figure of merit ZT as well, though the lower bound values obtained here were found to still be comparable to or slightly smaller than the expected bulk values in the same crystal direction. Analytical modeling also indicates higher doping than in bulk. Overall, HMS nanostructures appear to have the potential to demonstrate measurable size-induced ZT enhancement, especially if optimal doping and control over the crystallographic growth direction can be achieved. However, experimental methods to achieve reliable electrical contact to quality four-probe samples needs to be improved in order to fully investigate the thermoelectric potential of HMS nanostructures.
Book Synopsis Nano-scale Heat Transfer in Nanostructures by : Jihong Al-Ghalith
Download or read book Nano-scale Heat Transfer in Nanostructures written by Jihong Al-Ghalith and published by Springer. This book was released on 2018-03-06 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book introduces modern atomistic techniques for predicting heat transfer in nanostructures, and discusses the applications of these techniques on three modern topics. The study of heat transport in screw-dislocated nanowires with low thermal conductivity in their bulk form represents the knowledge base needed for engineering thermal transport in advanced thermoelectric and electronic materials, and suggests a new route to lower thermal conductivity that could promote thermoelectricity. The study of high-temperature coating composite materials facilitates the understanding of the role played by composition and structural characterization, which is difficult to approach via experiments. And the understanding of the impact of deformations, such as bending and collapsing on thermal transport along carbon nanotubes, is important as carbon nanotubes, due to their exceptional thermal and mechanical properties, are excellent material candidates in a variety of applications, including thermal interface materials, thermal switches and composite materials.
Book Synopsis Experimental Research on Thermal Transport in Individual One-dimensional Micro/nano Structures by : Pallavi Vellelacheruvu
Download or read book Experimental Research on Thermal Transport in Individual One-dimensional Micro/nano Structures written by Pallavi Vellelacheruvu and published by . This book was released on 2006 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Proceedings of 14th International Conference on Nanomaterials and Nanotechnology 2017 by : ConferenceSeries
Download or read book Proceedings of 14th International Conference on Nanomaterials and Nanotechnology 2017 written by ConferenceSeries and published by ConferenceSeries. This book was released on 2017-03-24 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: March 30- 31, 2017 Madrid, Spain Key Topics ; Nano Particles, Nano Electronic devices, Nano Scale Materials, Scope of Nanomaterials, Nanomaterials characterisation and synthesis, Nanozymes, Nanomaterials manufacturing technologies, Nano Structures, Nanomaterials Safety and regulations, Materiomics, Insilico nanostructure modelling, Applications of Nanomaterials, Characterization and properties of Nanomaterials, Advanced Nanomaterials, Nanotech products, Nanodevices and Systems, Nanomedical Devices, Nanotechnology applications, Biomedical Nanomaterials,
Book Synopsis Thermal and Electrical Transport Study of One Dimensional Nanomaterials by : Liang Yin
Download or read book Thermal and Electrical Transport Study of One Dimensional Nanomaterials written by Liang Yin and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents experimental and computational study of thermal and electrical transport in one-dimensional nanostructures. Synthesizing materials into one-dimensional nanowire has been proved very effective for suppressing the phonon contribution due to scattering at the wire boundaries. Three one-dimensional nanostructured thermoelectric candidates - SiGe nanowires, SrTiO3 nanowires, and ZnO nanowires - were presented and discussed in this dissertation. SiGe nanowires are successfully synthesized on a cleaned n-type (100) Si substrate coated with gold thin film as a catalytic metal, via the vapor-liquid-solid (VLS) growth method. The thermoelectric properties of SiGe nanowires with different diameter, Ge concentration, and phosphorus doping concentration were measured using a MEMS micro-device consisting of two suspended silicon nitride membranes in the temperature range of 60 K ~450 K. The experimental results were obtained by "simultaneously" measuring thermal conductivity, electrical conductivity, and thermopower. The ZT improvement is attributed to remarkable thermal conductivity reductions, which are thought to derive from the effective scattering of a broad range of phonons by alloying Si with Ge as well as by limiting phonon transport within the nanowire diameters. An improved model based on Boltzmann transport equation with relaxation time approximation was introduced for estimating thermoelectric properties of phosphorus heavily doped SiGe nanowires from 300 to 1200 K. All the electron and phonon scatterings were comprehensively discussed and utilized to develop the new model for estimating electrical conductivity, thermopower, and thermal conductivity of SiGe nanowires. As thermoelectric materials, oxide nanowires have great advantages comparing to other semiconductors. Two nanostructured materials, SrTiO3 nanotubes and ZnO nanowires, are introduced and successfully synthesized by simple methods. Thermal conductivity of ZnO nanowires with different diameter were characterized from 60 K to 450 K. In order to measure thermoelectric properties of one-dimensional nanostructures at temperature up to 800 K, a new temperature vacuum system was carefully designed and built from scratch. The thermal conductivity of ZnO nanowires with different diameters at high temperature were measured from 300 K to 800 K. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151175
Book Synopsis Molecular Dynamics by : Lichang Wang
Download or read book Molecular Dynamics written by Lichang Wang and published by BoD – Books on Demand. This book was released on 2012-04-05 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular Dynamics is a two-volume compendium of the ever-growing applications of molecular dynamics simulations to solve a wider range of scientific and engineering challenges. The contents illustrate the rapid progress on molecular dynamics simulations in many fields of science and technology, such as nanotechnology, energy research, and biology, due to the advances of new dynamics theories and the extraordinary power of today's computers. This first book begins with a general description of underlying theories of molecular dynamics simulations and provides extensive coverage of molecular dynamics simulations in nanotechnology and energy. Coverage of this book includes: Recent advances of molecular dynamics theory Formation and evolution of nanoparticles of up to 106 atoms Diffusion and dissociation of gas and liquid molecules on silicon, metal, or metal organic frameworks Conductivity of ionic species in solid oxides Ion solvation in liquid mixtures Nuclear structures
Book Synopsis An Experimental Investigation of the Thermopower of Low Dimensional Materials by : R. W. Trinder
Download or read book An Experimental Investigation of the Thermopower of Low Dimensional Materials written by R. W. Trinder and published by . This book was released on 1983 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Thermal Transport in Heterogeneous Nanostructures by : Man Li
Download or read book Thermal Transport in Heterogeneous Nanostructures written by Man Li and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heterogeneous nanostructures involve nanoscale interfaces with different materials components, such as matrix and fillers in composites, stacking planer structures in electronics, and aggregates of nanomaterials. Thermal transport in heterogenous nanostructures is critical to the safety and performance of various applications ranging from high temperature turbines, microelectronics, solar cells, thermoelectrics, buildings' thermal management and so on. However, it remains challenging to achieve rational control of the thermal properties in heterogeneous nanostructures due to limitations in current characterization techniques and fundamental understandings of interface thermal transport. My PhD research focuses on developing new thermal measurement techniques and investigating fundamental interface transport mechanisms through the combination of experiments and modeling, to provide rational control over heterogeneous nanostructures for better addressing practical heat management and energy conversion problems using nanoengineering. The study of thermal transport in heterogeneous nanostructures in my dissertation spans from technical development of new tools, experimental measurements at nanoscale interfaces and porous structures, and atomistic modelling of fundamental transport physics to practical device applications. First, I have developed a new metrology based on asymmetric beam time-domain thermoreflectance (AB-TDTR) that enables accurate measurements over three-dimensional thermal transport. Through the design of an asymmetric laser beam with controlled elliptical ratio and spot size, the experimental signals can be exploited to be dominantly sensitive to measure anisotropic thermal conductivity along the cross-plane or any specific in-plane directions. I have further applied this new approach to investigate anisotropic transport phenomena that enables unique applications. Second, I have explored the effects of crystal orientations and dipole-dipole interactions on interface thermal transport. In particular, for the first time, we have observed a record-high anisotropy ratio of 3.25 in the thermal boundary resistance across a prototype two-dimensional material, i.e., black phosphorus. Moreover, my study has resulted in the first observation of strong effects from long-range molecular dipole-dipole interactions on interface thermal transport. In addition, I have also investigated the heterogeneous integration of our recently developed new high thermal conductivity materials with prototyped high-power semiconductor, i.e., gallium nitride. Our in-situ measurement demonstrated substantially reduced hot-spot temperatures in devices using boron arsenide cooling substrates, beyond the best state-of-the-art HEMTs using diamond or silicon carbide. Lastly, I have investigated thermal transport in porous and mesoporous structures, including super-hydrophobic polymer aerogel, transparent mesoporous silica, and flexible tin selenide nanosheet films for applications in buildings, windows, and thermoelectric energy conversion.
Book Synopsis Nanofluids and Mass Transfer by : Mohammad Reza Rahimpour
Download or read book Nanofluids and Mass Transfer written by Mohammad Reza Rahimpour and published by Elsevier. This book was released on 2021-09-04 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the recent decades, efficiency enhancement of refineries and chemical plants has been become a focus of research and development groups. Use of nanofluids in absorption, regeneration, liquid-liquid extraction and membrane processes can lead to mass transfer and heat transfer enhancement in processes which results in an increased efficiency in all these processes. Nanofluids and Mass Transfer introduces the role of nanofluids in improving mass transfer phenomena and expressing their characteristics and properties. The book also covers the theory and modelling procedures in details and finally illustrates various applications of Nanofluids in mass transfer enhancement in various processes such as absorption, regeneration, liquid-liquid extraction and membrane processes and how can nanofluids increase mass transfer in processes. Introduces specifications of nanofluids and mechanisms of mass transfer enhancement by nanofluids in various mass transfer processes Discusses mass transfer enhancement in various mass transfer processes such as: absorption, regeneration, liquid-liquid extraction and membrane processes Offers modelling mass transfer and flow in nanofluids Challenges industrialization and scale up of nanofluids
Book Synopsis Experimental Investigations of Energy Carrier Interactions with Atomic Disorders and Artificial Long-range Orders by : Brandon Paul Smith
Download or read book Experimental Investigations of Energy Carrier Interactions with Atomic Disorders and Artificial Long-range Orders written by Brandon Paul Smith and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of nanoscale energy transport, conversion, and storage is at an exciting time with next-generation devices manipulating discrete energy carriers, e.g. phonons, photons, and electrons, in confined dimensions arriving closer to commercialization, such as solid-state flexible electronics and optoelectronics utilizing one dimension (1D) and two dimensional (2D) nanomaterials. The transport dynamics of quasiparticles and their coupling are modified, notably in low dimensional nanomaterials, with the inclusion of disorder and artificial long-range order. Through this lens, it is possible to probe interesting physics and draw out intrinsic properties of the nanomaterials. This is especially important for electronic systems and energy conversion & storage devices where heat generation and dissipation within nano- and microscale locations of nonequilibrium impedes continued advancement. This thesis examines outstanding questions concerning nanoscale thermal and thermoelectric transport in low-dimensional materials to further understanding of crystal disorder and artificial long-range order. Specifically, the material systems investigated are alloy disorder and surface roughness in semiconducting silicon germanium (SiGe) nanowires, microscale rippling in layered molybdenum disulfide (MoS2) flakes, intra- and interlayer interactions in bulk and monolayer MoS2, and artificially created, long-range domain walls in twisted bilayer graphene (TBG). The fundamental questions are addressed through electrothermal, optothermal, and scanning probe metrology techniques. First, eight-probe thermal conductivity measurements of SiGe nanowires show that alloying suppresses thermal transport, and the mean-free-paths of low-frequency phonons are suppressed by diffuse surface roughness scattering in nanowires. The diffuse surface scattering results in length-independent thermal conductivity for lengths over two micrometers. Similarly, four-probe thermal conductivity measurements reveal that microscale ripples have negligible effects on phonon transport in 2D layers as the ripple wavelengths and curvatures are much larger than the phonon mean free paths and wavelengths. The peak thermal conductivity is found to increase with decreasing Raman scattering intensity in the frequency range with vanishing phonon density of states in MoS2 indicating an important role of point defect scattering. In addition, this dissertation presents an experimental effort to employ micro-Raman spectroscopy to investigate local nonequilibrium among different phonon polarizations in MoS2 inside the focused laser spot. It also describes an exploration of ultra-high vacuum scanning probe microscopy for probing the local thermoelectric property of twisted bilayer graphene moiré superstructures
Book Synopsis Thermal Characterization of Nanostructures and Advanced Engineered Materials by : Vivek Kumar Goyal
Download or read book Thermal Characterization of Nanostructures and Advanced Engineered Materials written by Vivek Kumar Goyal and published by . This book was released on 2011 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Continuous downscaling of Si complementary metal-oxide semiconductor (CMOS) technology and progress in high-power electronics demand more efficient heat removal techniques to handle the increasing power density and rising temperature of hot spots. For this reason, it is important to investigate thermal properties of materials at nanometer scale and identify materials with the extremely large or extremely low thermal conductivity for applications as heat spreaders or heat insulators in the next generation of integrated circuits. The thin films used in microelectronic and photonic devices need to have high thermal conductivity in order to transfer the dissipated power to heat sinks more effectively. On the other hand, thermoelectric devices call for materials or structures with low thermal conductivity because the performance of thermoelectric devices is determined by the figure of merit Z=S 2 [sigma]/ K, where S is the Seebeck coefficient, K and [sigma] are the thermal and electrical conductivity, respectively. Nanostructured superlattices can have drastically reduced thermal conductivity as compared to their bulk counterparts making them promising candidates for high-efficiency thermoelectric materials. Other applications calling for thin films with low thermal conductivity value are high-temperature coatings for engines. Thus, materials with both high thermal conductivity and low thermal conductivity are technologically important. The increasing temperature of the hot spots in state-of-the-art chips stimulates the search for innovative methods for heat removal. One promising approach is to incorporate materials, which have high thermal conductivity into the chip design. Two suitable candidates for such applications are diamond and graphene. Another approach is to integrate the high-efficiency thermoelectric elements for on-spot cooling. In addition, there is strong motivation for improved thermal interface materials (TIMs) for heat transfer from the heat-generating chip to heat-sinking units. This dissertation presents results of the experimental investigation and theoretical interpretation of thermal transport in the advanced engineered materials, which include thin films for thermal management of nanoscale devices, nanostructured superlattices as promising candidates for high-efficiency thermoelectric materials, and improved TIMs with graphene and metal particles as fillers providing enhanced thermal conductivity. The advanced engineered materials studied include chemical vapor deposition (CVD) grown ultrananocrystalline diamond (UNCD) and microcrystalline diamond (MCD) films on Si substrates, directly integrated nanocrystalline diamond (NCD) films on GaN, free-standing polycrystalline graphene (PCG) films, graphene oxide (GOx) films, and "pseudo-superlattices" of the mechanically exfoliated Bi 2 Te 3 topological insulator films, and thermal interface materials (TIMs) with graphene fillers.
