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Field Emission Of Electrons From Vertically Aligned Single Walled Carbon Nanotubes
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Book Synopsis Field Emission of Electrons from Vertically Aligned Single-walled Carbon Nanotubes by : Daniel James Wasielewski
Download or read book Field Emission of Electrons from Vertically Aligned Single-walled Carbon Nanotubes written by Daniel James Wasielewski and published by . This book was released on 2010 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Carbon Nanotube and Related Field Emitters by : Yahachi Saito
Download or read book Carbon Nanotube and Related Field Emitters written by Yahachi Saito and published by John Wiley & Sons. This book was released on 2010-10-01 with total page 551 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes (CNTs) have novel properties that make them potentially useful in many applications in nanotechnology, electronics, optics and other fields of materials science. These characteristics include extraordinary strength, unique electrical properties, and the fact that they are efficient heat conductors. Field emission is the emission of electrons from the surface of a condensed phase into another phase due to the presence of high electric fields. CNT field emitters are expected to make a breakthrough in the development of field emission display technology and enable miniature X-ray sources that will find a wide variety of applications in electronic devices, industry, and medical and security examinations. This first monograph on the topic covers all aspects in a concise yet comprehensive manner - from the fundamentals to applications. Divided into four sections, the first part discusses the preparation and characterization of carbon nanotubes, while part two is devoted to the field emission properties of carbon nanotubes, including the electron emission mechanism, characteristics of CNT electron sources, and dynamic behavior of CNTs during operation. Part three highlights field emission from other nanomaterials, such as carbon nanowalls, diamond, and silicon and zinc oxide nanowires, before concluding with frontier R&D applications of CNT emitters, from vacuum electronic devices such as field emission displays, to electron sources in electron microscopes, X-ray sources, and microwave amplifiers. Edited by a pioneer in the field, each chapter is written by recognized experts in the respective fields.
Book Synopsis Synthesis and Field Emission Properties of Carbon Nanotube Films by :
Download or read book Synthesis and Field Emission Properties of Carbon Nanotube Films written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, vertically aligned multiwalled carbon nanotube films were grown by microwave plasma chemical vapor deposition (MWCVD). Through controlling the thickness of the iron thin film, carbon nanotubes with different diameters were obtained. When the thickness of the iron layer was reduced to 0.3-0.5 nm, single-wall and double-wall nanotubes were obtained with a high areal density (~ 1012/cm2) and vertical alignment. Scanning electron microscopy, Raman spectroscopy and high resolution transmission electron microscopy were employed to characterize the as-deposited nanotubes. In addition, a systematic study of the internal structure transition of the carbon nanotubes has been conducted and a growth model was proposed in terms of carbon surface and bulk diffusion. The field emission of the carbon nanotube films has also been explored in this study. Different measurement systems including a variable distance field emission system, a field emission imaging system, and a field electron emission system (FEEM) were employed. The effects of the diameter (multi-wall vs single- and double- wall), the adsorbates, and the temperature on the field emission properties of carbon nanotubes have been exhibited. Finally, two processes including hydrogen plasma etching and re-growth were used to treat the as-deposited film, and an increased emission site density was observed for the re-grown carbon nanotube film.
Book Synopsis Nanotube Cathodes by : Paul Albert Miller
Download or read book Nanotube Cathodes written by Paul Albert Miller and published by . This book was released on 2006 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still had a thin coating of glassy carbon surrounding them in a sheath-like manner. This glassy carbon, or nano-crystalline graphite, is likely to be a poor conductor due to phonon scattering, and should actually be deleterious for extracting electrons with electric fields. While we did not achieve the field emission reported for single-wall carbon nanotubes that spurred the idea for this project, at the year's very end, we had a breakthrough in materials growth and learned to control the growth of very-small diameter nanotubes ranging from 1.4 to 7 nm. The 1.4-nm nanotubes are single-walled and grow at only 530 C. This is the lowest temperature known to result in single-wall carbon nanotubes, and may be very important for many applications that where certain substrates could not be used due to the high temperatures commonly used for CNT growth. Critically important for field emission, these small diameter nanotubes, consisting of only a few concentric graphene cylindrical walls, do not show the presence of a poorly-conductive sheath material. Therefore, these nanotubes will almost definitely have superior field emission properties to those we already measured, and it is possible that they could provide the necessary field emission to make this project successful. Controlled spacing and lengths of these single-wall nanotubes have yet to be explored, along with correlating their structures to their improved field emission. Unfortunately, we did not discover the methods to grow these highly-crystalline and small diameter CNTs until late in the year. Since we did not achieve the necessary emission properties by mid-year, the project was ''prematurely'' terminated prior to the start of the second year. However, it should be noted that with the late developments, this work has not hit the proverbial ''brick wall''. Clearly the potential still exists to reproduce and even exceed the high emission results reported for randomly-oriented and curly single-wall carbon nanotubes, both in terms of total field emitting currents and perhaps more importantly, in reproducibility.
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 Field Emission from Vertically Aligned Carbon Nanotubes by : Robert D. Thompson
Download or read book Field Emission from Vertically Aligned Carbon Nanotubes written by Robert D. Thompson and published by . This book was released on 2006 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Field emission from vertically aligned carbon nanotube arrays by : Niraj Narasinha Kulkarni
Download or read book Field emission from vertically aligned carbon nanotube arrays written by Niraj Narasinha Kulkarni and published by . This book was released on 2002 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis High Electron Gain from Single Walled Carbon Nanotubes Stimulated by Interaction with an Electron Beam by :
Download or read book High Electron Gain from Single Walled Carbon Nanotubes Stimulated by Interaction with an Electron Beam written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes, hollow cylindrical structures made of carbon atoms with diameters in the order of a few nanometres, are attractive candidates for electron emission applications. A detailed characterization of the phenomenon so-called electron-stimulated field-emission from carbon nanotubes is presented in this thesis. An electron beam hitting the tip of a nanotube biased near the threshold of field-emission can stimulate the emission of a large number of electrons from the nanotube tip. The result of this interaction is that high electron gains can be obtained with very small stimulating electron beam currents. Electron gains of up to 2300 were recorded. This is important as this effect could form the basis of several vacuum nanoelectronic devices. Possible direct and indirect electron-nanotube interaction mechanisms responsible for this high gain are discussed and substantiated through simulations. The design and assembly of an ultra high vacuum apparatus for more controlled future experiments is also presented.
Book Synopsis Carbon Nanomaterials, Second Edition by : Yury Gogotsi
Download or read book Carbon Nanomaterials, Second Edition written by Yury Gogotsi and published by CRC Press. This book was released on 2013-10-24 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides information on synthesis, properties, and applications of carbon nanomaterials. With novel materials, such as graphene (atomically flat carbon) or carbon onions (carbon nanospheres), the family of carbon nanomaterials is rapidly growing. This book provides a state-of-the-art overview and in-depth analysis of the most important carbon nanomaterials. Each chapter is written by a leading expert in the field which ensures that both, a review on the subject along with emerging perspectives are provided to the reader.
Book Synopsis Conductive Effect of Increased Crystallinity of Single-Walled Carbon Nanotubes as Field Emitter by : Norihiro Shimoi
Download or read book Conductive Effect of Increased Crystallinity of Single-Walled Carbon Nanotubes as Field Emitter written by Norihiro Shimoi and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes (CNTs) exhibit chemical stability, thermal conductivity, mechanical strength, and unique properties as a quasi-one-dimensional material with nanoscale needle shape. Field-emission (FE) electron sources appear to be the most promising industrial application for CNTs, and their deployment is approaching practical utilization. So far, efforts to construct an FE cathode with single-walled carbon nanotubes (SWCNTs) have only managed to average out the large FE current fluctuations in a nonhomogeneous electron emitter plane and the short emission lifetime because the crystal defects in the carbon network in CNTs prevent the realization of a stable emission current. The utilization of CNTs to obtain an effective electronic device, one with stable emission and low FE current fluctuations, relies on the high crystallization of CNTs, a task that can be fulfilled by using highly crystalline SWCNTs (hc-SWCNTs). The author could succeed in developing a model of the flow of electrons through the inside of the hc-SWCNTs and SWCNTs with crystal defects to the outside using the fluctuations of the tunneling current. Therefore, we expect that the hc-SWCNTs are used as field emitters with stable emission and low power consumption for saving energy.
Book Synopsis Fabrication, Field Emission Properties and Theoretical Simulation of Triode-type Carbon Nanotube Emitter Arrays by : Jianfeng Wu
Download or read book Fabrication, Field Emission Properties and Theoretical Simulation of Triode-type Carbon Nanotube Emitter Arrays written by Jianfeng Wu and published by . This book was released on 2010 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes exhibit excellent field emission properties and will likely be prime candidates as electron sources in future vacuum electronic applications. Recent research has focused on enhancing field emission from traditional diode-type emitters by adding a gate electrode between the anode and the cathode. Since the gate to cathode (emitter) distance in this triode-type structure is small relative to the anode to cathode distance, this structure allows relatively small gate voltages to significantly enhance or dampen field emission. The key challenge for this research is: synthesizing vertically aligned carbon nanotube field emitters inside arrays of triode-type devices. The most common "top-down", etch-deposit-synthesis method of synthesizing carbon nanotubes inside gated cavities is discussed here, and a novel "bottom-up" method is presented. This new approach bypasses the lithography and wet chemistry essential to the etch-deposit-synthesis method, instead using a dual-beam focused ion beam (FIB) system to mill cavities into a multi-layered substrate. Here the substrate is designed such that the act of milling a hole simultaneously creates the gate structure and exposes the catalyst from which carbon nanotubes can then be grown. Carbon nanotubes are synthesized using plasma enhanced chemical vapor deposition (PECVD) rather than thermal chemical vapor deposition, due to the superior alignment of the PECVD growth. As dual-beam FIB and PECVD can both be largely computerized, this synthesis method is highly reproducible. The dual-beam FIB also permits a high degree of controllability in gate radius, cavity depth and emitter spacing. The effects of a host of PECVD growth parameters (initial catalyst thickness, gas concentration, growth temperature, temperature ramping rate, chamber pressure, and plasma voltage) were characterized so that the morphology of the carbon nanotube emitters could be controlled as well. This "bottom-up" method is employed to construct functional, large area carbon nanotube field emitter arrays (CNT FEAs). The role of the gate layer in field emission is examined experimentally as well as through theoretical models. Field emission testing revealed that increasing gate voltage by as little as 0.3 V had significant impact on the local electric fields, lowering the turn-on and threshold fields by 3.6 and 3.0 V/um, respectively, and increasing the field enhancement factor from 149 to 222. A quantum mechanical model of such triode-type field emission indicates that the local electric field generated by a negatively or positively biased gate directly impacts the tunneling barrier thickness and thus the achievable emission current. However, the geometry of triode-type devices (gate height, gate radius, emitter density) can influence the degree to which the gate voltage influences field emission. I demonstrate here an effective method of analytically calculating the effect of various such geometric parameters on the field emission. Results show that gate type (the height of the gate relative the emitter tip) can significantly impact the local electric field and hence the type of applications a device is suitable for. Side gates (gate height emitter height) induced the highest local electric field, while top gates (gate height emitter height) provided the greatest controllability. For all gate types, increasing the size of the gate opening increased the local electric field by diminishing the gate-emitter screening effect. However, gate voltages were able to enhance or inhibit the local electric field much more readily with smaller gate radii. Due to the strength of gate-emitter field screening in the triode-type structure, the spacing between emitters had virtually no impact on the local electric field, allowing relatively high emitter densities. These theoretical results, combined with a highly controllable synthesis method, provide valuable information and methodology for those designing and optimizing triode-type devices targeted at specific applications.
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 Nanostructured Carbon Electron Emitters and Their Applications by : Yahachi Saito
Download or read book Nanostructured Carbon Electron Emitters and Their Applications written by Yahachi Saito and published by CRC Press. This book was released on 2022-01-27 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon forms a variety of allotropes due to the diverse hybridization of s- and p-electron orbitals, including the time-honored graphite and diamond as well as new forms such as C60 fullerene, nanotubes, graphene, and carbyne. The new family of carbon isotopes—fullerene, nanotubes, graphene, and carbyne—is called “nanostructured carbon” or “nanocarbon.” These isotopes exhibit extreme properties such as ultrahigh mechanical strength, ultrahigh charge–carrier mobility, and high thermal conductivity, attracting considerable attention for their electronic and mechanical applications as well as for exploring new physics and chemistry in the field of basic materials science. Electron sources are important in a wide range of areas, from basic physics and scientific instruments to medical and industrial applications. Carbon nanotubes (CNTs) and graphene behave as excellent electron-field emitters owing to their exceptional properties and offer several benefits compared to traditional cathodes. Field emission (FE) produces very intense electron currents from a small surface area with a narrow energy spread, providing a highly coherent electron beam—a combination that not only provides us with the brightest electron sources but also explores a new field of electron beam–related research. This book presents the enthusiastic research and development of CNT-based FE devices and focuses on the fundamental aspects of FE from nanocarbon materials, including CNTs and graphene, and the latest research findings related to it. It discusses applications of FE to X-ray and UV generation and reviews electron sources in vacuum electronic devices and space thrusters. Finally, it reports on the new forms of carbon produced via FE from CNT.
Book Synopsis Field Emission from Aligned Single Walled Carbon Nanotubes Chemically Attached to N-type Silicon by : Cameron James Shearer
Download or read book Field Emission from Aligned Single Walled Carbon Nanotubes Chemically Attached to N-type Silicon written by Cameron James Shearer and published by . This book was released on 19?? with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Book Synopsis Nanomaterials Handbook by : Yury Gogotsi
Download or read book Nanomaterials Handbook written by Yury Gogotsi and published by CRC Press. This book was released on 2017-08-09 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt: This title features 11 new chapters unique to this edition, including chapters on grain boundaries in graphene, 2D metal carbides and carbonitrides, mechanics of carbon nanotubes and nanomaterials, biomedical applications, oxidation and purification of carbon nanostructures, sintering of nanoceramics, hydrothermal processing, nanofibers, and nanomaterials safety. It offers a comprehensive approach with a focus on inorganic and carbon-based nanomaterials, including fundamentals, applications, synthesis, and characterization. This book also provides a unique angle from the nanomaterial point of view on application, synthesis, and characterization not found in any other nanomaterials book on the market.
Book Synopsis Carbon Nanotubes by : Mohammed Rahman
Download or read book Carbon Nanotubes written by Mohammed Rahman and published by BoD – Books on Demand. This book was released on 2018-04-26 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book Carbon Nanotubes - Recent Progress contains a number of recent researches on synthesis, growth, characterization, development, and potential applications on carbon materials especially CNTs in nanoscale. It is a promising novel research from top to bottom that has received a lot of interest in the last few decades. It covers the advanced topics on the physical, chemical, and potential applications of CNTs. Here, the interesting reports on cutting-edge science and technology related to synthesis, morphology, control, hybridization, and prospective applications of CNTs are concluded. This potentially unique work offers various approaches on the R
