Ultrafast Electro-thermal Transport Through Nanoscale Electronic Materials and Interfaces PDF Download

Author: Christopher Perez
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Category :
Languages : en
Pages : 0

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Although silicon-based nanofabrication technology has satisfied computational demands for decades, the aggressive scaling of complementary metal oxide semiconductor (CMOS) technology to sub-5 nm geometries poses challenges that must be addressed at the materials level. One example is tuning electro-thermal transport in metal nanostructures to enhance the transfer of information and the dissipation of heat in integrated circuits. The manipulation of these pathways can be further optimized by integrating low-temperature passivation materials with varying thermal conductivities. Furthermore, the emergence of photonic interconnects presents an opportunity for the integration of electro-optic components that rely heavily on the movement, transfer, and recombination of charge carriers within photosensitive materials. All the above are governed by the fundamental limits of physical transfer mechanisms in semiconductors, bringing electron and phonon engineering --the control of heat and charge carriers in materials-- to the forefront of CMOS hardware design. This work explores the fundamental mechanisms and limits of electron-phonon transport in four individual material systems which can comprise different parts of a broader, electro-thermally optimized electronic system using primarily time-domain thermoreflectance (TDTR) and scanning ultrafast electron microscopy (SUEM) as probes. First, we discuss the electro-thermal characterization of iridium (Ir) as an emerging metal for high aspect ratio nanostructures on account of its favorable resistivity scaling with thickness. The exceptionally defect-free metal films offer minimal confounding microstructural effects and allow the probing of thermal anisotropy and cross-plane quasi-ballistic thermal transport in epitaxial Ir(001) interposed between Al and MgO(001). Such effects reveal a transition between three dominant cross-plane thermal transport mechanisms which include electron dominant, phonon dominant, and electron-phonon energy conversion dominant regimes at different thicknesses. Finally, we develop a phenomenological model that correctly describes the dominant transport regimes, providing insight into the thickness-dependent interplay between carriers in metals as well as enabling quick evaluation and potential scalability to broader material systems. Next, we describe defect-modulated thermal transport in sputtered aluminum nitride (AlN) thin films for enabling wide-bandgap (WBG), high-temperature, and high-power electronic devices deposited at back-end of the line (BEOL) compatible temperatures (

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 5

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Our research program on Ultrafast Thermal Transport at Interfaces advanced understanding of the mesoscale science of heat conduction. At the length and time scales of atoms and atomic motions, energy is transported by interactions between single-particle and collective excitations. At macroscopic scales, entropy, temperature, and heat are the governing concepts. Key gaps in fundamental knowledge appear at the transitions between these two regimes. The transport of thermal energy at interfaces plays a pivotal role in these scientific issues. Measurements of heat transport with ultrafast time resolution are needed because picoseconds are the fundamental scales where the lack of equilibrium between various thermal excitations becomes a important factor in the transport physics. A critical aspect of our work has been the development of experimental methods and model systems that enabled more precise and sensitive investigations of nanoscale thermal transport.

Author: Mr. Elah Bozorg-Grayeli
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Ultrafast thermoreflectance is a powerful technique designed to measure thermal properties in films less than a micrometer thick. Careful sample design and control over the measurement timescale allow spatial and temporal confinement of the measurement to a region of interest. This work explores the capability of nanosecond and picosecond thermoreflectance in capturing the thermal properties of a host of exotic materials used in next generation electronic devices. These include the phase change material Ge2Sb2Te5 (GST), diamond substrates for high electron mobility transistors (HEMT), and multilayer Mo/Si mirrors for extreme ultraviolet wavelengths (EUV). Nanosecond and picosecond thermoreflectance were used to determine the thermal properties of the phase change material, GST, along with several candidate electrode films (C, Ti, TiN, W, and WNx) and novel electrode multilayers (C-TiN and W-WNx). These results offer a material selection roadmap for device designers seeking to tune the thermal properties of their PCM cell. This work also reports picosecond thermoreflectance measurements of GST films sandwiched between TiN electrode layers and annealed at multiple temperatures. Thermal conductivity of the hexagonal close-packed (HCP) phase exceeds that of the face centered cubic (FCC) phase due to the addition of electron thermal conduction. Electron interface transport is shown to be negligible, implying that the addition of electrons as energy carriers does not significantly affect thermal boundary resistance (TBR). Thermal spreading analysis of a representative HEMT structure on diamond and SiC substrates shows that a device-substrate thermal interface resistance in excess of 20 m2 K GW-1 negates the benefits of diamond as a substrate material. Picosecond thermoreflectance measurements on multiple diamond samples were performed to determine the thermal conductivity, thermal anisotropy, and boundary resistance of diamond on AlN substrates. Further measurements on the top and bottom surfaces of a suspended diamond films demonstrated the thermal conductivity of the coalescence region (80 W m-1 K-1) and high quality layer (1350 W m-1 K-1) of a single diamond film. Using a two-layer model of the diamond film, we predict the thickness of the coalescence region and show it to be less than 1 [micrometer]. The operating temperatures of Mo/Si multilayers used in EUV lithography affect their lifetimes. Predicting the mirror/mask damage threshold fluence requires accurate knowledge of the mirror thermal properties. This study reports high temperature thermal properties of the TaN masking film, the MoSi2 intermetallic, and the room temperature properties of the Mo/Si multilayer. The thickness dependent electrical conductivity of TaN estimates the mean free path of electrons in the film unhindered by the material interfaces (~ 30 nm). Measurements on MoSi2 demonstrate the change in thermal conductivity due to crystallization, from 1.7 W m-1 K-1 in the amorphous phase to 2.8 W m-1 K-1 in the crystalline phase. Mo/Si results demonstrate thermal conductivity (1.1 W m-1 K-1) significantly lower than previous literature assumptions (4-5 W m-1 K-1). A finite element thermal model uses these results to predict the maximum EUV fluence allowed on a Mo/Si mirror for a single shot and for a one billion pulse lifetime before causing a reflectance loss of 1%.

Author: Lenan Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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The discovery and development of two-dimensional (2D) materials offer new opportunities for high-performance nanoscale electronics. However, new material systems involve new device architectures, which leads to new challenges on both the electronic and thermal design. While significant progress has been made to understand and engineer the electrical properties of 2D devices, the thermal problems remain relatively poorly understood. Since many 2D electronics can reach very high-power density (>104 W/cm2 ), the dense vertical integration of multilayers within a few nanometers leads to a significant temperature rise (>150 °C), which becomes the bottleneck of device performance. These thermal challenges are associated with two critical thermophysical properties of 2D materials, i.e., the thermal expansion and the interfacial thermal transport. In addition, to address the thermal management of 2D electronics, novel cooling approaches with insights gained from 2D thermal interfaces are in high demands. This thesis performed a systematic study on the thermal expansion and thermal transport of the van der Waals (vdW) bonded 2D interfaces, and developed highly efficient thermal management solutions based on two-phase cooling. First, we developed for the first time a pure experimental approach to accurately measure the thermal expansion coefficients(TECs) of various 2D materials. Our measurements confirmed the correct physical range of 2D monolayer TECs and hence addressed the more than two orders of magnitude discrepancies in literature. Second, we investigated the thermal transport across various 2D interfaces. In particular, we elucidated the role of vdW interaction in the anisotropic thermal transport of substrate-supported 2D monolayers and identified an optimal vdW interaction toward the maximum total heat transfer. On the other hand, we explored the twist-angle dependence of 2D interfacial thermal transport. We observed that depending on different material systems, the thermal transport of 2D materials can exhibit both strong and weak twist-angle dependences, which creates a new degree of freedom to manipulate heat at the atomic level. Lastly, with fundamental understanding of 2D thermal interfaces, we designed and optimized a liquid-vapor thin film evaporator based on microstructured surfaces, enabling high-performance thermal management of 2D electronics. This thesis provides a holistic understanding for the fundamental thermal properties of 2D materials and interfaces, which are critical to address the thermal crisis of 2D electronics. We believe the simulation, experimental, and design approaches developed in this thesis can serve as a guideline for the next-generation 2D electronics with unprecedented reliability and performance.

Author: Jiawei Zhou
Publisher:
ISBN:
Category :
Languages : en
Pages : 142

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Energy transport provides the fundamental basis for operation of devices from transistors to solar cells. Despite past theories that successfully illustrate the principles behind the energy transport based on solid state physics, the microscopic details of the energy transport are not always clear due to the lack of tool to quantify the contribution from different degrees of freedom. Recent progress in first principles computations and development in optical characterization has offered us new ways to understand the energy transport at the nanoscale in a quantitative way. In this thesis, by leveraging these techniques, we aim to providing a detailed understanding of thermal and thermoelectric energy transport in crystalline and disordered materials, especially about how the energy transport depends on atomistic level details such as chemical bondings. Specifically, we will discuss three examples. 1) Electron transport in semiconductors: how electrons propagate as they interact with lattice and impurities. 2) Interaction between charge and heat: how the free carriers have an impact on the heat dissipation in semiconductors 3) Heat conduction in polymers: how the heat transfer in an amorphous system depends on its molecular structures. In the case of electron transport, we developed and applied first principles simulation to show that a large electron mobility can benefit from symmetry-protected non-bonding orbitals. Such orbitals result in weak electron-lattice coupling that explains the unusually large power factors in half-Heusler materials - a good thermoelectric material system. By devising an optical experiment to probe the ultrafast thermal decay, we quantified the effect of electron-phonon interaction on the thermal transport. Our results show that the thermal conductivity can be significantly affected by the free carriers. Lastly, we built a theoretical model to understand the heat conduction in amorphous polymers, and used this knowledge to design materials that are heat-conducting yet soft. These understandings will potentially facilitate discovery of new material systems with beneficial charge and heat transport characteristic.

Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 0309467691
Category : Science
Languages : en
Pages : 347

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The laser has revolutionized many areas of science and society, providing bright and versatile light sources that transform the ways we investigate science and enables trillions of dollars of commerce. Now a second laser revolution is underway with pulsed petawatt-class lasers (1 petawatt: 1 million billion watts) that deliver nearly 100 times the total world's power concentrated into a pulse that lasts less than one-trillionth of a second. Such light sources create unique, extreme laboratory conditions that can accelerate and collide intense beams of elementary particles, drive nuclear reactions, heat matter to conditions found in stars, or even create matter out of the empty vacuum. These powerful lasers came largely from U.S. engineering, and the science and technology opportunities they enable were discussed in several previous National Academies' reports. Based on these advances, the principal research funding agencies in Europe and Asia began in the last decade to invest heavily in new facilities that will employ these high-intensity lasers for fundamental and applied science. No similar programs exist in the United States. Opportunities in Intense Ultrafast Lasers assesses the opportunities and recommends a path forward for possible U.S. investments in this area of science.

Author: Marc J. Madou
Publisher: CRC Press
ISBN: 1482274663
Category : Technology & Engineering
Languages : en
Pages : 1992

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Book Description
Now in its third edition, Fundamentals of Microfabrication and Nanotechnology continues to provide the most complete MEMS coverage available. Thoroughly revised and updated the new edition of this perennial bestseller has been expanded to three volumes, reflecting the substantial growth of this field. It includes a wealth of theoretical and practical information on nanotechnology and NEMS and offers background and comprehensive information on materials, processes, and manufacturing options. The first volume offers a rigorous theoretical treatment of micro- and nanosciences, and includes sections on solid-state physics, quantum mechanics, crystallography, and fluidics. The second volume presents a very large set of manufacturing techniques for micro- and nanofabrication and covers different forms of lithography, material removal processes, and additive technologies. The third volume focuses on manufacturing techniques and applications of Bio-MEMS and Bio-NEMS. Illustrated in color throughout, this seminal work is a cogent instructional text, providing classroom and self-learners with worked-out examples and end-of-chapter problems. The author characterizes and defines major research areas and illustrates them with examples pulled from the most recent literature and from his own work.

Author: Yatish T. Shah
Publisher: CRC Press
ISBN: 1315305933
Category : Technology & Engineering
Languages : en
Pages : 1112

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The book details sources of thermal energy, methods of capture, and applications. It describes the basics of thermal energy, including measuring thermal energy, laws of thermodynamics that govern its use and transformation, modes of thermal energy, conventional processes, devices and materials, and the methods by which it is transferred. It covers 8 sources of thermal energy: combustion, fusion (solar) fission (nuclear), geothermal, microwave, plasma, waste heat, and thermal energy storage. In each case, the methods of production and capture and its uses are described in detail. It also discusses novel processes and devices used to improve transfer and transformation processes.

Author: LIAO
Publisher: IOP Publishing Limited
ISBN: 9780750317368
Category : Energy conversion
Languages : en
Pages : 440

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Book Description
This book brings together leading names in the field of nanoscale energy transport to provide a comprehensive and insightful review of this developing topic. The text covers new developments in the scientific basis and the practical relevance of nanoscale energy transport, highlighting the emerging effects at the nanoscale that qualitatively differ from those at the macroscopic scale. Throughout the book, microscopic energy carriers are discussed, including photons, electrons and magnons. State-of-the-art computational and experimental nanoscale energy transport methods are reviewed, and a broad range of materials system topics are considered, from interfaces and molecular junctions to nanostructured bulk materials. Nanoscale Energy Transport is a valuable reference for researchers in physics, materials, mechanical and electrical engineering, and it provides an excellent resource for graduate students.

Author: Marc J. Madou
Publisher: CRC Press
ISBN: 1420055119
Category : Technology & Engineering
Languages : en
Pages : 658

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Book Description
Providing a clear theoretical understanding of MEMS and NEMS, Solid-State Physics, Fluidics, and Analytical Techniques in Micro- and Nanotechnology focuses on nanotechnology and the science behind it, including solid-state physics. It provides a clear understanding of the electronic, mechanical, and optical properties of solids relied on in integrated circuits (ICs), MEMS, and NEMS. After exploring the rise of Si, MEMS, and NEMS in a historical context, the text discusses crystallography, quantum mechanics, the band theory of solids, and the silicon single crystal. It concludes with coverage of photonics, the quantum hall effect, and superconductivity. Fully illustrated in color, the text offers end-of-chapter problems, worked examples, extensive references, and a comprehensive glossary of terms. Topics include: Crystallography and the crystalline materials used in many semiconductor devices Quantum mechanics, the band theory of solids, and the relevance of quantum mechanics in the context of ICs and NEMS Single crystal Si properties that conspire to make Si so important Optical properties of bulk 3D metals, insulators, and semiconductors Effects of electron and photon confinement in lower dimensional structures How evanescent fields on metal surfaces enable the guiding of light below the diffraction limit in plasmonics Metamaterials and how they could make for perfect lenses, changing the photonic field forever Fluidic propulsion mechanisms and the influence of miniaturization on fluid behavior Electromechanical and optical analytical processes in miniaturized components and systems The first volume in Fundamentals of Microfabrication and Nanotechnology, Third Edition, Three-Volume Set, the book presents the electronic, mechanical, and optical properties of solids that are used in integrated circuits, MEMS, and NEMS and covers quantum mechanics, electrochemistry, fluidics, and photonics. It lays the foundation for a qualitative and quantitative theoretical understanding of MEMS and NEMS.