Download or read book Structure de bandes et transport lectronique dans les nanotubes de carbone sous champ magn tique intense written by Sébastien Nanot and published by . This book was released on 2009 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Des mesures de transport électronique dans des nanotubes de carbone multiparois individuels sous champ magnétique pulsé (60T) sont présentées dans cette thèse. L'objectif est d'observer les modifications de la dispersion électronique par le champ magnétique. Des nanotubes de très bonne qualité cristalline sont connectés sur des distances courtes entre contacts, permettant d'atteindre des régimes de transport quasi-balistiques ou faiblement diffusifs, la paroi externe contribuant principalement. La configuration transistor permet de moduler l'énergie des porteurs (niveau de Fermi) sur plusieurs sous-bandes via un potentiel électrostatique (dit de grille). Afin de préciser la contribution des parois plus internes, une étude en spectroscopie Raman est présentée dans un premier temps. Nous constatons que l'intensité du transfert de charges entre parois successives varie fortement d'un feuillet à l'autre. L'étude sous champ magnétiques de nanotubes de parois externes semiconductrices et métalliques est ensuite présentée. Lorsque le champ magnétique est appliqué perpendiculairement à l'axe du nanotube, la formation de niveaux de Landau propagatifs est mise en évidence. Celle-ci se traduit par des modulations des conditions de résonance dans un régime de type Fabry-Pérot électronique, par la fermeture du gap électronique d'une paroi semiconductrice ainsi que la réintroduction de la rétrodiffusion dans une paroi métallique. Ce dernier effet s'accompagne d'un ancrage du niveau de Fermi vers celui de Landau se formant à énergie nulle à très fort champ. L'ensemble de ces résultats est en accord avec des modèles théoriques prenant en compte un désordre homogène. Enfin, l'effet Aharonov-Bohm sur plusieurs périodes et plusieurs sous-bandes est observé sous un champ parallèle à l'axe du nanotube. La métallicité de la paroi externe et la correspondance entre la tension de grille et l'énergie des porteurs sont obtenues en comparant les oscillations de conductance expérimentales à un modèle obtenu pour un cas parfait. Afin de décrire en détail la signature magnétique, les diminutions des transmissions aux contacts et la contribution de défauts sont qualitativement étudiées.

Download or read book Transport lectronique dans les nanotubes de carbone tude sous champ magn tique written by and published by . This book was released on 2006 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cette thèse a pour objet l'étude du transport électronique dans les nanotubes de carbone grâce à l'utilisation combinée d'un fort champ magnétique (60T) et d'un contrôle électrostatique du dopage électronique. Il s'agit alors de montrer les rôles clés joués par la structure de bande en énergie et par le désordre. Plusieurs types de tubes métalliques de qualité structurale variable ont été étudiés. Selon le rapport entre le libre parcours moyen élastique (le) et la circonférence du nanotube (L), différents régimes apparaissent. Lorsque le

Download or read book Physics of Carbon Nanotube Devices written by Francois Leonard and published by William Andrew. This book was released on 2008-11-18 with total page 411 pages. Available in PDF, EPUB and Kindle. Book excerpt: Possibly the most impactful material in the nanotechnology arena, carbon nanotubes have spurred a tremendous amount of scientific research and development. Their superior mechanical and chemical robustness makes them easily manipulable and allows for the assembly of various types of devices, including electronic, electromechanical, opto-electronic and sensing devices.In the field of nanotube devices, however, concepts that describe the properties of conventional devices do not apply. Carbon nanotube devices behave much differently from those using traditional materials, and offer entirely new functionality. This book – designed for researchers, engineers and graduate students alike – bridges the experimental and theoretical aspects of carbon nanotube devices. It emphasizes and explains the underlying physics that govern their working principles, including applications in electronics, nanoelectromechanical systems, field emission, optoelectronics and sensing. Other topics include: electrical contacts, p-n junctions, transistors, ballistic transport, field emission, oscillators, rotational actuators, electron-phonon scattering, photoconductivity, and light emission. Many of the aspects discussed here differ significantly from those learned in books or traditional materials, and are essential for the future development of carbon nanotube technology.• Bridges experimental and theoretical aspects of carbon nanotube devices, focusing on the underlying physics that govern their working principles • Explains applications in electronics, nanoelectromechanical systems, field emission, optoelectronics and sensing. • Other topics include: electrical contacts, p-n junctions, transistors, ballistic transport, field emission, oscillators, rotational actuators, electron-phonon scattering, photoconductivity, and light emission. • Covers aspects that significantly differ from those learned in traditional materials, yet are essential for future advancement of carbon nanotube technology.* Bridges experimental and theoretical aspects of carbon nanotube devices, focusing on the underlying physics that govern their working principles * Explains applications in electronics, nanoelectromechanical systems, field emission, optoelectronics and sensing.* Other topics include: electrical contacts, p-n junctions, transistors, ballistic transport, field emission, oscillators, rotational actuators, electron-phonon scattering, photoconductivity, and light emission* Covers aspects that significantly differ from those learned in traditional materials, yet are essential for future advancement of carbon nanotube technology.

Download or read book Carbon Nanotubes written by Stephanie Reich and published by John Wiley & Sons. This book was released on 2008-09-26 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes are exceptionally interesting from a fundamental research point of view. Many concepts of one-dimensional physics have been verified experimentally such as electron and phonon confinement or the one-dimensional singularities in the density of states; other 1D signatures are still under debate, such as Luttinger-liquid behavior. Carbon nanotubes are chemically stable, mechanically very strong, and conduct electricity. For this reason, they open up new perspectives for various applications, such as nano-transistors in circuits, field-emission displays, artificial muscles, or added reinforcements in alloys. This text is an introduction to the physical concepts needed for investigating carbon nanotubes and other one-dimensional solid-state systems. Written for a wide scientific readership, each chapter consists of an instructive approach to the topic and sustainable ideas for solutions. The former is generally comprehensible for physicists and chemists, while the latter enable the reader to work towards the state of the art in that area. The book gives for the first time a combined theoretical and experimental description of topics like luminescence of carbon nanotubes, Raman scattering, or transport measurements. The theoretical concepts discussed range from the tight-binding approximation, which can be followed by pencil and paper, to first-principles simulations. We emphasize a comprehensive theoretical and experimental understanding of carbon nanotubes including - general concepts for one-dimensional systems - an introduction to the symmetry of nanotubes - textbook models of nanotubes as narrow cylinders - a combination of ab-initio calculations and experiments - luminescence excitation spectroscopy linked to Raman spectroscopy - an introduction to the 1D-transport properties of nanotubes - effects of bundling on the electronic and vibrational properties and - resonance Raman scattering in nanotubes.

Download or read book Conduction in Carbon Nanotube Networks written by Robert A. Bell and published by Springer. This book was released on 2015-06-13 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis exploits the ability of the linear-scaling quantum mechanical code ONETEP to analyze systems containing many thousands of atoms. By implementing an electron transport capability to the code, it also investigates a range of phenomena associated with electrical conduction by nanotubes and, in particular, the process of transport electrons between tubes. Extensive work has been done on the conductivity of single carbon nanotubes. However, any realistic wire made of nanotubes will consist of a large number of tubes of finite length. The conductance of the resulting wire is expected to be limited by the process of transferring electrons from one tube to another.These quantum mechanical calculations on very large systems have revealed a number of incorrect claims made previously in the literature. Conduction processes that have never before been studied at this level of theory are also investigated.

Download or read book Applied Physics of Carbon Nanotubes written by Slava V. Rotkin and published by Springer Science & Business Media. This book was released on 2005-10-14 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book describes the state-of-the-art in fundamental, applied and device physics of nanotubes, including fabrication, manipulation and characterization for device applications; optics of nanotubes; transport and electromechanical devices and fundamentals of theory for applications. This information is critical to the field of nanoscience since nanotubes have the potential to become a very significant electronic material for decades to come. The book will benefit all all readers interested in the application of nanotubes, either in their theoretical foundations or in newly developed characterization tools that may enable practical device fabrication.

Download or read book Transport lectronique sous champ magn tique intense dans des gaz d lectrons bidimensionnels written by Fabrice Iacovella and published by . This book was released on 2015 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cette thèse présente une étude de transport électronique dans des gaz d'électrons bidimensionnels sous champ magnétique intense (60T). La première partie est dédiée au gaz d'électrons formé à l'interface entre deux isolants de bandes LaAlO3/SrTiO3. Sur la plage de champ magnétique exploré, la non-linéarité de la résistance de Hall permet d'établir un régime de conduction multi-bande. Une majorité des porteurs de charge de faible mobilité (μ ~100 cm2/Vs) occupe une bande tandis qu'une minorité de porteurs de haute mobilité (μ>1000 cm2/Vs) occupent au moins deux autres bandes de conduction. La présence d'oscillations de Shubnikov-de Haas à très basse température (450mK) est associée aux porteurs de haute mobilité. La fréquence et l'amplitude des oscillations sont profondément modifiées lorsque la densité de porteurs est modulée par couplage électrostatique. Cette étude laisse entrevoir un système électronique complexe, encore peu exploré et dans lequel un nombre important de paramètres (conditions de croissance, densité de porteurs ...) sont susceptibles d'affecter les propriétés de transport électronique. La deuxième partie est consacrée à l'étude de films inhomogènes de graphène issus d'un dépôt chimique en phase vapeur. Deux échantillons aux propriétés électroniques radicalement différentes ont été étudiés. L'un d'entre eux est constitué d'un ensemble de grains de graphène multi-feuillets fortement couplés les uns aux autres. De larges oscillations de la magnéto-résistance sont observées sous champ magnétique intense, présentant un caractère pseudo-périodique en fonction du facteur de remplissage. Cette observation suggère un régime de transport dans lequel la formation des niveaux de Landau est propre à chaque "grains" de graphène multi-couche, prévenant ainsi l'établissement du régime d'effet Hall quantique sans pour autant détruire la quantification du spectre énergétique en niveaux discrets dans la réponse globale de l'échantillon. Dans un autre échantillon, la présence d'un désordre fort localise la fonction d'onde au niveau des impuretés ou des grains de graphène multi-couche. A basse température, la conductivité est nulle (caractère isolant) tant que la tension de polarisation ne dépasse pas un certain seuil. Dans ce régime de transport, la magnéto-résistance positive observée expérimentalement possède la forme fonctionnelle du modèle VRH (Variable Range Hopping), impliquant le confinement magnétique des fonctions d'onde électroniques. La troisième partie est consacrée à la recherche des états conducteurs de surface dans les isolants topologiques, en particulier les composés Bi2Se3 et Bi2Te3. L'existence de ces états électroniques aux propriétés particulières a été prédite par de nombreuses études théoriques et confirmée expérimentalement par ARPES. Leur mise en évidence par transport électronique reste cependant controversée. Nous avons souhaité utiliser un champ magnétique intense pour tenter de révéler ces états de surface à travers l'observation d'oscillations de Shubnikov-de Haas à très basse température. Bien que les résultats obtenus n'aient pas permis d'apporter une preuve irréfutable du phénomène recherché, ces derniers seront commentés au regard de la littérature existante.

Download or read book Carbon Based Electronics written by Ashok Srivastava and published by CRC Press. This book was released on 2015-03-19 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discovery of one-dimensional material carbon nanotubes in 1991 by the Japanese physicist Dr. Sumio Iijima has resulted in voluminous research in the field of carbon nanotubes for numerous applications, including possible replacement of silicon used in the fabrication of CMOS chips. One interesting feature of carbon nanotubes is that these can be me

Download or read book Graphene Carbon Nanotubes and Nanostructures written by James E. Morris and published by CRC Press. This book was released on 2017-07-28 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene, Carbon Nanotubes, and Nanostructures: Techniques and Applications offers a comprehensive review of groundbreaking research in nanofabrication technology and explores myriad applications that this technology has enabled. The book examines the historical evolution and emerging trends of nanofabrication and supplies an analytical understanding of some of the most important underlying nanofabrication technologies, with an emphasis on graphene, carbon nanotubes (CNTs), and nanowires. Featuring contributions by experts from academia and industry around the world, this book presents cutting-edge nanofabrication research in a wide range of areas. Topics include: CNT electrodynamics and signal propagation models Electronic structure calculations of a graphene–hexagonal boron nitride interface to aid the understanding of experimental devices based on these heterostructures How a laser field would modify the electronic structure and transport response of graphene, to generate bandgaps The fabrication of transparent CNT electrodes for organic light-emitting diodes Direct graphene growth on dielectric substrates, and potential applications in electronic and spintronic devices CNTs as a promising candidate for next-generation interconnect conductors CMOS–CNT integration approaches, including the promising localized heating CNT synthesis method CNTs in electrochemical and optical biosensors The synthesis of diamondoids by pulsed laser ablation plasmas generated in supercritical fluids, and possible applications The use of DNA nanostructures in lithography CMOS-compatible silicon nanowire biosensors The use of titanium oxide-B nanowires to detect explosive vapors The properties of protective layers on silver nanoparticles for ink-jet printing Nanostructured thin-film production using microreactors A one-stop reference for professionals, researchers, and graduate students working in nanofabrication, this book will also be useful for investors who want an overview of the current nanofabrication landscape.

Download or read book Contribution la mod lisation th orique et l tude du transport quantique dans les dispositifs base de nanotubes de carbone written by Rémi Avriller and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les nanotubes de carbone sont des structures tubulaires obtenues en enroulant une feuille de graphène sur elle-même. La manière d'effectuer cette enroulement détermine la chiralité du tube, ainsi que l'ensemble de ses propriétés électroniques et vibrationnelles. Du fait de la nature ondulatoire de l'électron et de la faible dimensionnalité des nanotubes de carbone, cette structure de bandes est fortement modulée par l'application d'un champ magnétique externe. La présence d'un potentiel de désordre(rupture de l'invariance par translation) ou l'excitation d'un mécanisme d'interaction entre électrons et modes phonons optiques ont aussi des conséquences importantes sur cette structure électronique. L'objectif de cette thèse est de s'intéresser aux propriétés de transport quantique des nanotubes de carbone, propriétés déterminées par la compétition entre interférences quantiques, structure de bandes et mécanismes d'interaction. Pour ce faire, une étude détaillée des nanotubes de carbone désordonnés, dopés à l'azote ou au bore sera menée, étude permettant de modéliser de manière fine le hamiltonien de désordre ainsi que de sonder les lois d'échelles de la conductance. La présence d'un champ magnétique statique et uniforme sera considérée, ainsi que ses conséquences sur les régimes de transport à faible tension de polarisation(formation d'un niveau de Landau et oscillation Aharonov-Bohm). Finalement, nous nous intéresserons au rôle des collisions inélastiques entre électrons et phonons optiques de haute symétrie, sur les propriétés de transport quantique(rôle priviligié lorsque la tension de polarisation franchit un seuil d'excitation inélastique). Du fait de la faible dimensionnalité, l'approximation adiabatique n'est plus valide, et un traitement cohérent dans l'espace de Fock électron-phonon doit être mené. Pour chacune de ces études, un modèle hamiltonien effectif est construit et le problème du transport quantique résolu analytiquement ou numériquement.

Download or read book Graphene and Carbon Nanotubes written by Ermin Malic and published by John Wiley & Sons. This book was released on 2013-04-12 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: A first on ultrafast phenomena in carbon nanostructures like graphene, the most promising candidate for revolutionizing information technology and communication The book introduces the reader into the ultrafast nanoworld of graphene and carbon nanotubes, including their microscopic tracks and unique optical finger prints. The author reviews the recent progress in this field by combining theoretical and experimental achievements. He offers a clear theoretical foundation by presenting transparently derived equations. Recent experimental breakthroughs are reviewed. By combining both theory and experiment as well as main results and detailed theoretical derivations, the book turns into an inevitable source for a wider audience from graduate students to researchers in physics, materials science, and electrical engineering who work on optoelectronic devices, renewable energies, or in the semiconductor industry.

Download or read book Contribution la mod lisation th orique et l tude du transport quantique dans les dispositifs base de nanotubes de carbone written by Rémi Avriller and published by . This book was released on 2008 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les nanotubes de carbone sont des structures tubulaires obtenues en enroulant une feuille de graphène sur elle-même. La manière d'effectuer cette enroulement détermine la chiralité du tube, ainsi que l'ensemble de ses propriétés électroniques et vibrationnelles. Du fait de la nature ondulatoire de l'électron et de la faible dimensionnalité des nanotubes de carbone, cette structure de bandes est fortement modulée par l'application d'un champ magnétique externe. La présence d'un potentiel de désordre(rupture de l'invariance par translation) ou l'excitation d'un mécanisme d'interaction entre électrons et modes phonons optiques ont aussi des conséquences importantes sur cette structure électronique. L'objectif de cette thèse est de s'intéresser aux propriétés de transport quantique des nanotubes de carbone, propriétés déterminées par la compétition entre interférences quantiques, structure de bandes et mécanismes d'interaction. Pour ce faire, une étude détaillée des nanotubes de carbone désordonnés, dopés à l'azote ou au bore sera menée, étude permettant de modéliser de manière fine le hamiltonien de désordre ainsi que de sonder les lois d'échelles de la conductance. La présence d'un champ magnétique statique et uniforme sera considérée, ainsi que ses conséquences sur les régimes de transport à faible tension de polarisation(formation d'un niveau de Landau et oscillation Aharonov-Bohm). Finalement, nous nous intéresserons au rôle des collisions inélastiques entre électrons et phonons optiques de haute symétrie, sur les propriétés de transport quantique(rôle priviligié lorsque la tension de polarisation franchit un seuil d'excitation inélastique). Du fait de la faible dimensionnalité, l'approximation adiabatique n'est plus valide, et un traitement cohérent dans l'espace de Fock électron-phonon doit être mené. Pour chacune de ces études, un modèle hamiltonien effectif est construit et le problème du transport quantique résolu analytiquement ou numériquement.

Download or read book An Introduction to Graphene and Carbon Nanotubes written by John E. Proctor and published by CRC Press. This book was released on 2017-02-03 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes and graphene have been the subject of intense scientific research since their relatively recent discoveries. This book introduces the reader to the science behind these rapidly developing fields, and covers both the fundamentals and latest advances. Uniquely, this book covers the topics in a pedagogical manner suitable for undergraduate students. The book also uses the simple systems of nanotubes and graphene as models to teach concepts such as molecular orbital theory, tight binding theory and the Laue treatment of diffraction. Suitable for undergraduate students with a working knowledge of basic quantum mechanics, and for postgraduate researchers commencing their studies into the field, this book will equip the reader to critically evaluate the physical properties and potential for applications of graphene and carbon nanotubes.

Download or read book Carbon Nanotubes From Basic Research to Nanotechnology written by Valentin N. Popov and published by Springer Science & Business Media. This book was released on 2006-05-03 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is about 15 years that the carbon nanotubes have been discovered by Sumio Iijima in a transmission electron microscope. Since that time, these long hollow cylindrical carbon molecules have revealed being remarkable nanostructures for several aspects. They are composed of just one element, Carbon, and are easily produced by several techniques. A nanotube can bend easily but still is very robust. The nanotubes can be manipulated and contacted to external electrodes. Their diameter is in the nanometer range, whereas their length may exceed several micrometers, if not several millimeters. In diameter, the nanotubes behave like molecules with quantized energy levels, while in length, they behave like a crystal with a continuous distribution of momenta. Depending on its exact atomic structure, a single-wall nanotube –that is to say a nanotube composed of just one rolled-up graphene sheet– may be either a metal or a semiconductor. The nanotubes can carry a large electric current, they are also good thermal conductors. It is not surprising, then, that many applications have been proposed for the nanotubes. At the time of writing, one of their most promising applications is their ability to emit electrons when subjected to an external electric field. Carbon nanotubes can do so in normal vacuum conditions with a reasonable voltage threshold, which make them suitable for cold-cathode devices.

Download or read book Doping of Carbon Nanotubes written by Sergey Bulyarskiy and published by Springer. This book was released on 2017-07-01 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the control of electronic properties of carbon nanotubes. It presents thermodynamic calculations of the formation of impurities and defects in the interaction of nanotubes with hydrogen, oxygen, nitrogen and boron, based on theoretical models of the formation of defects in carbon nanotubes. It is shown that doping and adsorption lead to changes in the electronic structure of the tubes as well as to the appearance of impurity states in the HOMO-LUMO gap. The book presents examples of specific calculations for doping of carbon nanotubes with oxygen, hydrogen, nitrogen and boron, together with numerous experimental results and a comparison with the author’s thermodynamic calculations. Possible directions of the technological processes of optimization are pointed out, as well as the perspectives of p-n-transition creation with the help of carbon nanotube arrays. The results presented were derived from the physics of the processes and a theoretical model of the technological processes. Though a wealth of empirical information on doping nanotubes has been accumulated in the scientific literature, what is lacking is a theoretical model for their analysis. As such, the book develops a thermodynamic model of the self-organization of structural elements in multicomponent systems – including carbon nanotubes, clusters and precipitates in condensed matter – and subsequently adapts it to the doping of carbon nanotubes. This approach allows readers to gain a far deeper understanding of the processes of doping carbon nanotubes.

Download or read book Electrical Conduction in Graphene and Nanotubes written by Shigeji Fujita and published by John Wiley & Sons. This book was released on 2013-10-25 with total page 283 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written in a self-contained manner, this textbook allows both advanced students and practicing applied physicists and engineers to learn the relevant aspects from the bottom up. All logical steps are laid out without omitting steps. The book covers electrical transport properties in carbon based materials by dealing with statistical mechanics of carbon nanotubes and graphene - presenting many fresh and sometimes provoking views. Both second quantization and superconductivity are covered and discussed thoroughly. An extensive list of references is given in the end of each chapter, while derivations and proofs of specific equations are discussed in the appendix. The experienced authors have studied the electrical transport in carbon nanotubes and graphene for several years, and have contributed relevantly to the understanding and further development of the field. The content is based on the material taught by one of the authors, Prof Fujita, for courses in quantum theory of solids and quantum statistical mechanics at the University at Buffalo, and some topics have also been taught by Prof. Suzuki in a course on advanced condensed matter physics at the Tokyo University of Science. For graduate students in physics, chemistry, electrical engineering and material sciences, with a knowledge of dynamics, quantum mechanics, electromagnetism and solid-state physics at the senior undergraduate level. Includes a large numbers of exercise-type problems.

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.