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Molecular Jet Growth Of Carbon Nanotubes And Dense Vertically Aligned Nanotube Arrays
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Book Synopsis Molecular Jet Growth of Carbon Nanotubes and Dense Vertically Aligned Nanotube Arrays by :
Download or read book Molecular Jet Growth of Carbon Nanotubes and Dense Vertically Aligned Nanotube Arrays written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A method of growing a carbon nanotube includes the step of impinging a beam of carbon-containing molecules onto a substrate to grow at least one carbon nanotube on the catalyst surface.
Book Synopsis Aligned Carbon Nanotubes by : Zhifeng Ren
Download or read book Aligned Carbon Nanotubes written by Zhifeng Ren and published by Springer Science & Business Media. This book was released on 2012-09-05 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives a survey of the physics and fabrication of carbon nanotubes and their applications in optics, electronics, chemistry and biotechnology. It focuses on the structural characterization of various carbon nanotubes, fabrication of vertically or parallel aligned carbon nanotubes on substrates or in composites, physical properties for their alignment, and applications of aligned carbon nanotubes in field emission, optical antennas, light transmission, solar cells, chemical devices, bio-devices, and many others. Major fabrication methods are illustrated in detail, particularly the most widely used PECVD growth technique on which various device integration schemes are based, followed by applications such as electrical interconnects, nanodiodes, optical antennas, and nanocoax solar cells, whereas current limitations and challenges are also be discussed to lay the foundation for future developments.
Book Synopsis Reliable Growth of Vertically Aligned Carbon Nanotube Arrays by Chemical Vapor Deposition and In-situ Measurement of Fundamental Growth Kinetics in Oxygen-free Conditions by : JUNG BIN. IN
Download or read book Reliable Growth of Vertically Aligned Carbon Nanotube Arrays by Chemical Vapor Deposition and In-situ Measurement of Fundamental Growth Kinetics in Oxygen-free Conditions written by JUNG BIN. IN and published by . This book was released on 2011 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vertically-aligned carbon nanotube (VACNT) arrays are both an important technological system, and a fascinating system for studying basic principles of nanomaterial synthesis. However, despite continuing efforts for the past decade, important questions about this process remain largely unexplained. Recently, nanotube research investigations have been conducted, aiming at revealing the underlying growth mechanisms, rather than merely studying the feasibility on new growth methods. Nonetheless, growth deactivation and the accompanying termination mechanisms still remain a topic of nanotube synthesis science. Due to the extremely small size, however, direct characterization of various transport and conversion events occurring at the catalyst surface is not an easy task. Thus investigations on growth kinetics are the first step to resolve questions about growth mechanism. Before exploring kinetic aspects of the growth process, one must achieve reliable growth conditions since growth non-reproducibility retards obtaining reliable growth data and undermines the scientific value of the data. In order to improve growth reliability, several factors that may contribute to growth non-reproducibility were identified and thereafter mitigated. Firstly, a simulation study was conducted to achieve insight into temperature and velocity profile of gases inside the reactor since gas flow dynamics can render growth environment near the substrate non-uniform. Interestingly, when argon gas was used as the main carrier gas, natural convective flow emerged, generating flow circulation before the gas reached the substrate placed at the center of the tube reactor. This flow circulation was not favorable for controlled gas introduction. This problem could be resolved by using a more heat- and momentum- conductive gas such as helium. Secondly, atomic force microscopy of annealed catalyst revealed that the aluminum sub-layer was not thermally stable at the growth temperature although this material has been widely used as a barrier layer to avoid silicide formation of catalyst on silicon substrates. In this respect, aluminum oxide should be a better choice, but under-stoichiometry of the aluminum oxide layer, which originated from sputter target degradation, affected thermal stability of the layer. Reactive sputtering by oxygen addition greatly enhanced thermal stability, and finally defect-free catalyst nanoparticles were formed by thermal annealing. Thirdly, the effect of the small part-per-million levels of oxygen-containing species on VACNT growth revealed that oxygen-containing gas impurities in nominally pure gas sources have a great influence on growth kinetics in a positive way; their presence increases catalyst lifetime and growth yield. However, the kinetic behavior that is highly sensitive to gas purity is prone to showing an interfering kinetic trend where the real mechanism is masked by the significant gas impurity effect. The stark difference in catalytic lifetime after the introduction of high-performance gas purifiers shows that extremely tight control of the reaction gas composition purity is necessary to obtain controlled growth of CNTs under atmospheric chemical vapor deposition (CVD) conditions. Finally, more reliable growth of VACNTs was achieved, and thereafter the next step for fundamental growth kinetics measurement was followed. Finally, the CVD system was equipped with an optical micrometer that enables in-situ measurement of the height of growing VACNTs, which have advantageous structure facilitating measurement of growth kinetics since the array height has a robust correlation with growth yield and thereby growth rate. Various ethylene and hydrogen combinations were examined to capture growth kinetics related to different gas environment. The measured initial growth rates were linearly proportional to ethylene concentration, whereas a reciprocal relation was observed with respect to hydrogen concentration. The apparent activation energy was higher than reported in references. Flow rate variation experiments revealed that gas phase reaction is involved as the crucial growth step, which supports the observed high activation energy. Consequently, a growth model was proposed so that it could reasonably fit the initial growth rate data. Kinetic aspects related to growth deactivation were explored by measuring the final growth height and catalyst lifetime. Unlike growth with unpurified gases, growth became much less sensitive to gas composition after purification. Importantly, it was observed that growth deactivates by deficit of carbon source when relatively low ethylene was introduced. This result is surprising since ethylene pressure should be high enough at the catalyst, considering the calculated sticking coefficient of ethylene is very low, approximately 10^-5. Thus it substantiates the idea that catalyst-mediated gas pretreatment process is critical to sustain nanotube growth. Importantly, this idea challenges the widely accepted growth termination concept whereby nanotube stops growing due to catalyst encapsulation by excessive carbon. Indeed, reduced flow rate of gas mixture increased growth yield remarkably by promoting the gas pretreatment over the catalyst. Catalyst ripening, or steric hindrance by interaction of nanotubes can be an alternative reason for growth termination, but analysis of morphologies of the annealed catalyst and as-grown nanotubes revealed that their effects were not significant for the corresponding growth conditions.
Book Synopsis Growth and Characterization of Vertically Aligned Carbon Nanotubes for Interconnect Applications by : Dingyou Zhang
Download or read book Growth and Characterization of Vertically Aligned Carbon Nanotubes for Interconnect Applications written by Dingyou Zhang and published by . This book was released on 2010 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Growth of Vertically Aligned Carbon Nanotubes with Multilayered Catalysts by : Peter Simiao Wang
Download or read book Growth of Vertically Aligned Carbon Nanotubes with Multilayered Catalysts written by Peter Simiao Wang and published by . This book was released on 2008 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nanotoxicology written by Vineet Kumar and published by CRC Press. This book was released on 2018-03-12 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the application of nanotechnology in the myriad disciplines of science and engineering--from agriculture, pharmaceuticals, material science, and biotechnology to sensors, electronics, and mechanical and electrical engineering--brings benefits it also can produce serious threats to human health and the environment that must be evaluated. The unique properties of nanomaterials make them different from their bulk counterparts. In addition to such unique properties, the nanometric size of nanomaterials can invite some detrimental effects on the health and well-being of living organisms and the environment. Thus, it is important to distinguish nanomaterials with such ill effects from nanomaterials with no or minimum toxicity. Nanotoxicology: Toxicity Evaluation, Risk Assessment and Management covers issues such as the basic principles of nanotoxicity, methods used for nanotoxicity evaluation, risk assessment and its management for nanomaterial toxicity with a focus on current trends, limitations, challenges, and future directions of nanotoxicity evaluation. Various experts from different countries discuss these issues in detail in this book. This will be helpful to researchers, educators, and students who are interested in research opportunities for avoiding the environmental and health hazards of nanomaterials. This book will also be useful for industrial practitioners, policy makers, and other professionals in the fields of toxicology, medicine, pharmacology, food, drugs, and other regulatory sciences.
Book Synopsis Carbon Nanotube Arrays - by : Sean Michael Foradori
Download or read book Carbon Nanotube Arrays - written by Sean Michael Foradori and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconducting, single walled carbon nanotubes (CNTs) are exceptional electronic materials with high current carrying capacity, a tunable band gap, and nanoscale dimensions. Single CNTs in research devices have demonstrated these excellent material properties. Extrapolation of these single CNT results to devices with many CNTs in tightly packed and highly aligned arrays indicates that CNTs can exceed the performance of existing silicon based devices in many applications by operating at lower voltages and using less energy. The performance of array based devices has not yet met these high expectations, however, due in part to practical challenges in fabricating arrays and integrating those arrays into devices. Aligned arrays can be deposited using many different processes to generate a wide range of CNT packing densities and array morphologies. The morphology and packing density both can affect device performance. Polymer wrapped CNTs with high semiconductor purity are often used in these arrays, but the polymer wrapper must be removed from the CNT array to achieve the best device performance. Chapter 2 examines the impact of CNT bundles on the performance of field effect transistors (FETs) with relatively weak gates. These bundles, colinear aggregates containing multiple CNTs, are formed during some array fabrication processes and can behave differently from individual CNTs. When using relatively weak gates, bundles have a current density similar to individual CNTs, but they have different threshold voltages than individual CNTs, meaning their conductivity turns on and off at different gate voltages. Arrays with a mixture of individual and bundled CNTs make devices with poor subthreshold swing because the gate cannot turn the whole array off at any particular voltage; the array turns off gradually as the gate voltage changes. Chapter 3 examines bundles in FETs with strong ion gel gates. A strong gate can turn on multiple CNTs in a bundle, increasing their current density relative to individual CNTs. An FET with a strong gate and a CNT array containing many bundles will have a higher transconductance than a device with an array containing only individual CNTs. This can be useful in radio frequency transistors because their high frequency performance improves as transconductance increases, but is degraded by parasitic capacitance effects if the channel width is increased. By using an array of bundled CNTs instead of an array of individual CNTs, the transconductance can be increased without increasing the channel width. Chapter 4 describes a strategy to fabricate monolayer arrays with high packing density and very little bundling. Passing a substrate through a macroscopic liquid-liquid interface can deposit aligned arrays of CNTs at the liquid-liquid-substrate contact line. The new strategy uses lithographically defined, microscopic water droplets on substrates to form a contact line that is more stable and improves the array deposition. The advantage of patterned microscopic droplets is that the contact line is pinned by the hydrophilic/hydrophobic border of the chemical pattern, and is decoupled from the motions of the substrate and macroscopic liquid-liquid interface. This relatively stable contact line moves as each CNT is deposited, allowing subsequent CNTs to deposit adjacent to the previously deposited ones, improving the alignment and increasing the packing density to 250 CNTs ℗æm-1 with very little bundling. Devices made using these arrays have exceptionally high current density and transconductance of 1.9 mA ℗æm-1 and 1.2 mS ℗æm-1 at a channel length of 60 nm using just a 0.6 V drain voltage. This is a >2x performance improvement over arrays formed with similar conditions but deposited at the contact line of the macroscopic interface. Finally, Chapter 5 investigates a yttrium (Y) based post-deposition process used to mitigate the effects of wrapping polymer in CNT FETs. Though this process has been used for several years, very little information has been reported about how it works. We use physical and spectroscopic measurements to examine the mechanism, selectivity, extent of etching, and range of conditions available for removing the wrapping polymer PFO-BPy from CNTs. The Y-treatment process consists of depositing 3 nm of metallic Y on the sample, annealing in air at a fixed temperature and time, then etching the sample in dilute HCl for 5 seconds, and rinsing in DI water. Annealing at 90°C or cooler for 30 minutes will oxidize ~0.5 nm of a PFO-BPy film, forming highly oxidized carbonate, carboxylate and/or carbonyl groups, allowing it to dissolve in dilute aqueous acid. Repeated Y-treatment cycles will etch more material, and thicker layers of up to 2.5 nm can be etched by annealing at 250°C for 120 minutes. Reactions with sp2 based CNTs and graphene only occur at elevated temperatures, allowing selective removal of wrapping polymer from CNTs at lower temperatures. Furthermore, the yttrium process can remove all parts of the PFO-BPy polymer molecule, in contrast to high-temperature vacuum annealing which only removes alkyl side groups and leaves much of the polymer chain intact.
Book Synopsis Growth of Vertically-aligned Carbon Nanotubes and Their Application as Electron Field Emitters by : Benjamin Ulmen
Download or read book Growth of Vertically-aligned Carbon Nanotubes and Their Application as Electron Field Emitters written by Benjamin Ulmen and published by . This book was released on 2007 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Growth and Processing of Vertically Aligned Multiwalled Carbon Nanotubes by : Lakshman Kumar Vanga
Download or read book Growth and Processing of Vertically Aligned Multiwalled Carbon Nanotubes written by Lakshman Kumar Vanga and published by . This book was released on 2004 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Interaction of Light with Vertically Aligned Arrays of Carbon Nanotubes by : Timothy Patrick Butler
Download or read book The Interaction of Light with Vertically Aligned Arrays of Carbon Nanotubes written by Timothy Patrick Butler and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Controlled Growth of Vertically Aligned Carbon Nanotubes on Metal Substrates by : Zhaoli Gao
Download or read book Controlled Growth of Vertically Aligned Carbon Nanotubes on Metal Substrates written by Zhaoli Gao and published by . This book was released on 2014 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Perspective of Carbon Nanotubes by : Hosam El-Din Saleh
Download or read book Perspective of Carbon Nanotubes written by Hosam El-Din Saleh and published by BoD – Books on Demand. This book was released on 2019-12-11 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes belong to new nanomaterials and have been known for almost 20 years, but their history is somewhat lengthier. They have been identified as promising candidates for various applications.High-temperature preparation techniques are conventional techniques for the synthesis of carbon nanotubes using arc discharge or laser ablation, but today these methods are being replaced by low-temperature vapor deposition techniques, since orientation, alignment, nanotube length, diameter, purity, and density of carbon nanotubes can be precisely controlled. The synthesis of carbon nanotubes by chemical vapor deposition on catalyst arrays leads to nanotube models grown from specific sites on surfaces. The controlled synthesis of nanotubes opens up interesting possibilities in nanoscience and nanotechnologies, including electrical, mechanical and electromechanical properties and devices, chemical functionalization, surface chemistry and photochemistry, molecular sensors, and interfacing with moderate biological systems.Carbon nanotubes are used in many applications due to their unique electrical, mechanical, optical, thermal, and other properties. Conductive and high-strength composite materials, energy saving and energy conversion devices, sensors, visualization of field emissions and sources of radiation, means for storing hydrogen, and nanoscale semiconductor devices, probes, and interconnections are some of the many applications of carbon nanotubes.
Book Synopsis Microsupercapacitors by : Kazufumi Kobashi
Download or read book Microsupercapacitors written by Kazufumi Kobashi and published by Woodhead Publishing. This book was released on 2021-10-01 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microsupercapacitors systematically guides the reader through the key materials, characterization techniques, performance factors and potential applications and benefits to society of this emerging electrical energy storage solution. The book reviews the technical challenges in scaling down supercapacitors, covering materials, performance, design and applications perspectives. Sections provide a fundamental understanding of microsupercapacitors and compare them to existing energy storage technologies. Final discussions consider the factors that impact performance, potential tactics to improve performance, barriers to implementation, emerging solutions to those barriers, and a future outlook. This book will be of particular interest to materials scientists and engineers working in academia, research and development. Provides a concise introduction of the fundamental science, related technological challenges, and solutions that microsupercapacitors can offer Compares microsupercapacitors with current technologies Reviews the applications of new strategies and the challenge of scaling down supercapacitors Covers the most relevant applications, including energy storage, energy harvesting, sensors and biomedical devices
Author :Mildred S. Dresselhaus Publisher :Springer Science & Business Media ISBN 13 :3642833799 Total Pages :391 pages Book Rating :4.6/5 (428 download)
Book Synopsis Graphite Fibers and Filaments by : Mildred S. Dresselhaus
Download or read book Graphite Fibers and Filaments written by Mildred S. Dresselhaus and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book was begun after three of the present authors gave a series of in vited talks on the subject of the structure and properties of carbon filaments. This was at a conference on the subject of optical obscuration, for which submicrometer diameter filaments with high length-to-diameter ratios have potential applications. The audience response to these talks illustrated the need of just one scientific community for a broader knowledge of the struc ture and properties of these interesting materials. Following the conference it was decided to expand the material presented in the conference proceedings. The aim was to include in a single volume a description of the physical properties of carbon fibers and filaments. The research papers on this topic are spread widely in the literature and are found in a broad assortment of physics, chemistry, materials science and engineering and polymer science journals and conference proceedings (some of which are obscure). Accordingly, our goal was to produce a book on the subject which would enable students and other researchers working in the field to gain an overview of the subject up to about 1987.
Download or read book Laser Ablation written by E. Fogarassy and published by Newnes. This book was released on 2012-12-02 with total page 943 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the proceedings of the largest conference ever held on this subject. The strong interest in this field is largely due to the fact that both fundamental aspects of laser-surface interaction as well as applied techniques for thin film generation and patterning were treated in detail by experts from around the world.
Download or read book Carbon Nanotubes written by M. Meyyappan and published by CRC Press. This book was released on 2004-07-28 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes, with their extraordinary mechanical and unique electronic properties, have garnered much attention in the past five years. With a broad range of potential applications including nanoelectronics, composites, chemical sensors, biosensors, microscopy, nanoelectromechanical systems, and many more, the scientific community is more moti
Book Synopsis Handbook of Visual Display Technology by : Janglin Chen
Download or read book Handbook of Visual Display Technology written by Janglin Chen and published by Springer. This book was released on 2012-01-23 with total page 2700 pages. Available in PDF, EPUB and Kindle. Book excerpt: This handbook offers a comprehensive description of the science, technology, economic and human interface factors associated with the displays industry. With expert contributions from over 150 international display professionals and academic researchers, it covers all classes of display device and discusses established principles, emergent technologies, and particular areas of application.