Download or read book Characterization of Carbon Nanotube Based Thin Film Field Emitter written by Niraj Sinha and published by . This book was released on 2008 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, carbon nanotubes (CNTs) have emerged as one of the best field emitters for a variety of technological applications. The field emitting cathodes have several advantages over the conventional thermionic cathodes: (i) current density from field emission would be orders of magnitude greater than in the thermionic case, (ii) a cold cathode would minimize the need for cooling, and (iii) a field emitting cathode can be miniaturized. In spite of good performance of such cathodes, the procedure to estimate the device current is not straight forward and the required insight towards design optimization is not well understood. In addition, the current in CNT-based thin film devices shows fluctuation. Such fluctuation in field emission current is not desirable for many biomedical applications such as x-ray devices. The CNTs in a thin film undergo complex dynamics during field emission, which includes processes such as (i) evolution, (ii) electromechanical interaction, (iii) thermoelectric heating, (iv) ballistic transport, and (v) electron gas flow. These processes are coupled and nonlinear. Therefore, they must be analyzed accurately from the stability and long-term performance point of view. In this research, we develop detailed physics-based models of CNTs considering the aspects mentioned above.
Download or read book Microscopic Characterization of Electron Field Emission from Carbon Nanotubes and Carbon Thin film Electron Emitters written by Lars-Ola Nilsson and published by . This book was released on 2001 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book From Diamond to Carbon Nanotube Field Emitter written by O. Groning and published by . This book was released on 2001 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper we review the physics and the expectations that were put into the negative electron affinity (NEA) mediated field emission of chemical vapor deposition CVD diamond films and how the emitter technology made possible by this mechanism could have challenged the classical metal micro-tip field emitter arrays. We discuss the dependency between emitter performance of micro-tip emitter arrays and feature size (size of the field enhancing tip) and due to this to the connection between emitter performance and fabrication costs. We introduce the concept of the field enhancement distribution function f(beta) for a useful characterization of the field emission properties of thin film emitter and show how this distribution function can be measured by scanning anode field emission microscopy. Using 1(beta) measured on a thin film of randomly oriented multiwalled carbon nanotubes we show that even these kinds of low cost emitters can show a field emission performance comparable to micro-tip arrays, yet that the large spread in field enhancement values between the individual emitter prevent this performance to be fully exploited. This because the field range in which such thin film emitters can be operated is limited due to emitter disruption and triggering of vacuum arcs. Simulations show how resistor-limited emission can solve these limitations.
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.
Download or read book Nano assembled Carbon Nanotube Thin Film Based Microstructures Field effect Transistors and Acetylcholine Biosensors written by Wei Xue (Mechanical engineer) and published by . This book was released on 2007 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Carbon Nanotube Based Thin Films Synthesis and Properties written by Qiguan Wang and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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
Download or read book Carbon Nanotubes written by Jose Mauricio Marulanda and published by BoD – Books on Demand. This book was released on 2011-08-01 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes (CNTs), discovered in 1991, have been a subject of intensive research for a wide range of applications. In the past decades, although carbon nanotubes have undergone massive research, considering the success of silicon, it has, nonetheless, been difficult to appreciate the potential influence of carbon nanotubes in current technology. The main objective of this book is therefore to give a wide variety of possible applications of carbon nanotubes in many industries related to electron device technology. This should allow the user to better appreciate the potential of these innovating nanometer sized materials. Readers of this book should have a good background on electron devices and semiconductor device physics as this book presents excellent results on possible device applications of carbon nanotubes. This book begins with an analysis on fabrication techniques, followed by a study on current models, and it presents a significant amount of work on different devices and applications available to current technology.
Download or read book Characterizations and Applications of Carbon Nanotube Thin Film Devices written by Michael Robert Gasper and published by . This book was released on 2016 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this thesis is to study the characteristics of carbon nanotube thin lms and apply them as detectors of microwave power. Using measured reflection data, S11, the relative permittivity and loss tangent of carbon nanotubes is extracted. These parameters are used to define a custom, frequency dependent material in HFSS, an electromagnetic finite element analysis solver. This new material definition allows one to simulate structures more complicated than the Corbino disc. The basic idea is to use a simple device to characterize the carbon nanotubes and use the data to simulate more complicated devices. A new 2-port twinax structure is analyzed using HFSS in order to extract the scattering parameters. MAXWELL, an electromagnetic field solver, is used to determine the DC potential distribution in the structure and is compared with a simple analytical model. Experiments for power detection are done using carbon nanotube thin lms deposited on sapphire substrates with Corbino disc test structures. These structures have been used to realize a microwave power sensor that operates at and above room temperature. Current vs voltage curve traces have been collected at various temperatures to evaluate the temperature dependent resistance of the carbon nanotube thin lm Corbino discs. The thermal time constant of the carbon nanotubes was found in order to determine how fast the device may respond when used as a microwave bolometer. Corbino effect measurements were then taken to observe the effect of an applied magnetic field on the resistance of the device. Such tuning of resistance can be of potential use in performance optimization of the power detection scheme. Device degradation was observed due to exposure to extreme temperatures (200C). New devices are now needed to continue work on carbon nanotube thin films. Photolithography masks have been designed and a photolithography process developed in order to fabricate Corbino disc structures and the new twinax structures.
Download or read book Carbon Nanotubes written by Siva Yellampalli and published by IntechOpen. This book was released on 2011-07-20 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes are one of the most intriguing new materials with extraordinary properties being discovered in the last decade. The unique structure of carbon nanotubes provides nanotubes with extraordinary mechanical and electrical properties. The outstanding properties that these materials possess have opened new interesting researches areas in nanoscience and nanotechnology. Although nanotubes are very promising in a wide variety of fields, application of individual nanotubes for large scale production has been limited. The main roadblocks, which hinder its use, are limited understanding of its synthesis and electrical properties which lead to difficulty in structure control, existence of impurities, and poor processability. This book makes an attempt to provide indepth study and analysis of various synthesis methods, processing techniques and characterization of carbon nanotubes that will lead to the increased applications of carbon nanotubes.
Download or read book Carbon Nanotube Field Emitter Array and Its Application to Novel X ray Systems written by Yunhan Li and published by . This book was released on 2018 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the emergence of ever more demanding X-ray imaging applications, including radiotherapy, radiography, computed tomography and tomosynthesis, there is a tendency to use field emission (FE) to take the place of thermionic emission in X-ray generation. Carbon nanotube (CNT) field emitter array (FEA) is able to provide enhanced current and low energy dispersion for X-ray generation. The low operating temperature, instantaneous response, and small size of CNT FEA enable efficient and controllable FE performance for high spatial and temporal resolution X-ray imaging and instantaneous switching among multiple X-ray sources. Challenges are still remaining for CNT FEA study and development. The first is the insufficient understanding of FE uniformity of CNT FEA and CNT emitter failure mechanism, which limits the development of stable and reliable CNT FEA. The second is the lack of applications of CNT FEA for the emergence of novel X-ray imaging applications that require dose adjustments, fluence field modulation, and shape variation. In this thesis, recent advances in CNT FE and field emitters are comprehensively reviewed. Issues related to the principles, characteristics, and applications of CNT based FE are discussed. The research starts with a fundamental study of understanding the FE uniformity and emitter failure mechanism of CNT FEA by designing and demonstrating a simple and reliable field emission microscopy method using PMMA (Poly (methyl methacrylate)) thin film with microscopic camera. This novel approach is able to resolve the challenges of observing FE uniformity of CNT FEA and CNT field emitter failure behaviour. The unique phenomenon of light emission and Coulomb explosion of CNT field emitter failure induced by FE is represented and systematically characterized, which is a combined effect of Joule heating and excessive charging. Then, individual ballast of vertically aligned CNT FEA using silicon current limiters is designed and fabricated, which exhibits improved reliability and stability. The CNT FEA is applied to a low-cost self-contained and self-focusing compact X-ray source integrated with resonant transformer. The X-ray source can be powered by low voltage to generate pulsed X-ray and achieve sub-millimetre resolution. Using finite element analysis and Monte Carlo simulation, CNT FEA based two dimensional multi-pixel X-ray source is designed and experimentally verified, which is feasible for X-ray fluence field modulation in next generation X-ray imaging systems.
Download or read book A Thin Film Triode Type Carbon Nanotube Field Electron Emission Cathode written by Graham Patrick Sanborn and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The current technological age is embodied by a constant push for increased performance and efficiency of electronic devices. This push is particularly observable for technologies that comprise free electron sources, which are used in various technologies including electronic displays, x-ray sources, telecommunication equipment, and spacecraft propulsion. Performance of these systems can be increased by reducing weight and power consumption, but is often limited by a bulky electron source with a high energy demand. Carbon nanotubes (CNTs) show favorable properties for field electron emission (FE) and performance as electron sources. This dissertation details the developments of a uniquely designed Spindt type CNT field emission array (CFEA), from initial concept to working prototype, to specifically prevent electrical shorting of the gate. The CFEA is patent pending in the United States. Process development enabled fabrication of a CFEA with a yield of up to 82%. Furthermore, a novel oxygen plasma etch process was developed to reverse shorting after CNT synthesis. CFEA testing demonstrates FE with a current density of up to 293 Î1/4A/cmÂ2 at the anode and 1.68 mA/cmÂ2 at the gate, with lifetimes in excess of 100 hours. A detailed analysis of eighty tested CFEAs revealed three distinct types of damage. Surprisingly, about half of the damaged chips are not electrically shorted, indicating that the CFEAs are very robust. Potential applications of this technology as cathodes for spacecraft electric propulsion were explored. Exposure to an operating electric propulsion thruster showed no significant effect or damage to the CFEAs, marking the first experimental study of CNT field emitters in an electric propulsion environment. A second effort in spacecraft propulsion is a collaboration with the Air Force Institute of Technology (AFIT). CFEAs are the payload on an AFIT developed Cube Satellite, called ALICE, to test electron emission in the space environment. ALICE has passed flight tests and is awaiting launch scheduled for 5 December 2013.
Download or read book Fabrication and Characterization of Carbon Nanotube Thin films for Gas Sensing Applications written by Ahmed Abdelhalim and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Carbon and Oxide Nanostructures written by Noorhana Yahya and published by Springer Science & Business Media. This book was released on 2011-01-12 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume covers all aspects of carbon and oxide based nanostructured materials. The topics include synthesis, characterization and application of carbon-based namely carbon nanotubes, carbon nanofibres, fullerenes, carbon filled composites etc. In addition, metal oxides namely, ZnO, TiO2, Fe2O3, ferrites, garnets etc., for various applications like sensors, solar cells, transformers, antennas, catalysts, batteries, lubricants, are presented. The book also includes the modeling of oxide and carbon based nanomaterials. The book covers the topics: Synthesis, characterization and application of carbon nanotubes, carbon nanofibres, fullerenes Synthesis, characterization and application of oxide based nanomaterials. Nanostructured magnetic and electric materials and their applications. Nanostructured materials for petro-chemical industry. Oxide and carbon based thin films for electronics and sustainable energy. Theory, calculations and modeling of nanostructured materials.
Download or read book Thin Film Nanomaterials Synthesis Properties and Innovative Energy Applications written by Sampat G. Deshmukh and published by Bentham Science Publishers. This book was released on 2024-07-25 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin Film Nanomaterials: Synthesis, Properties and Innovative Energy Applications provides a comprehensive overview of the synthesis, properties, and cutting-edge applications of thin film nanomaterials. Each chapter explores different aspects of thin film synthesis and its application in energy devices, showcasing different metal-based and carbon nanomaterials . The book begins with a discussion on the synthesis and characterization of cadmium and zinc sulphide thin films for opto-electronics energy devices. Subsequent chapters delve into critical reviews of CIGS thin film nanomaterials, deposition techniques for metal oxide nanocomposite films, and nanostructured TiO2@carbon films for photocatalytic applications. Bandgap engineering, optical properties of composite films, and recent advancements in metal oxide thin films are also covered. Additionally, the synthesis and characteristics of iron oxide films for solar cell and green energy storage applications are discussed. Chapters on challenges and future prospects of CNT-based cathode emitters and advanced characterizations of nanocrystalline ferrimagnetic thin films provide valuable insights into emerging technologies. This book is an essential resource for professors, scientists, engineers, research scholars, postdocs, and undergraduate/graduate students seeking to explore the forefront of nanomaterials and their applications in energy systems.
Download or read book Synthesis and Characterization of Carbon Nanotube reinforced Copper Thin Films written by Cornelia Otto and published by . This book was released on 2006 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
