Download or read book Out of equilibrium transport in quantum dots structures written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Neste trabalho estudamos as propriedades eletrônicas e de transportede uma molécula artificial diatômica que consiste de dois pontos quânticosconectados a dois contatos submetidos a um potencial externo. Cada pontoquântico é descrito por um nível de energia no qual os elétrons estãofortmente correlacionados pela interação Coulombiana no interior e entreos pontos quânticos. Duas topologias são consideradas para o sistema:uma corresponde aos dois pontos dispostos numa linha de condução e ooutro a uma configuração em paralelo. O problema é tratado com asfunções de Green obtidas a partir do formalismo de Keldysh para o sistemafora do equilíbrio. Estas funções permitem o cálculo da carga nos pontosquânticos e da corrente elétrica no sistema. A física do sistema é controladaprincipalmente pelas várias interações Coulombianas. Para a configuraçãoem paralelo existem dois canais interferindo para a propagação do elétronpelo sistema, cujas propriedades dependem do estado de carga de cadaponto quântico. Para a configuração em série a corrente é controlada pelapossibilidade da carga ser drenada de um ponto quântico ao outro. O estadode carga em cada ponto quântico e a corrente elétrica são discutidos emdetalhe para as duas configurações e para diferentes valores dos parâmetrosque definem o sistema.
Download or read book Non Equilibrium Quantum Dots Transport written by and published by . This book was released on 1990 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electronic transport through three-dimensionally confined semiconductor quantum dots is investigated and analyzed. The spectrum corresponds to resonant tunneling from laterally confined emitter contact subbands through the discrete three-dimensionally confined quantum dot states. Momentum non-conservation is observed in these structures.
Download or read book Non equilibrium Electron Transport Through a Double Quantum Dot System written by Verena Körting and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantum Coherent and Non equilibrium Transport in Etched Open Quantum Dots written by Arunkumar Ramamoorthy and published by . This book was released on 2003 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nonequilibrium Electron Transport in Quantum Dot and Quantum Point Contact Systems written by Anasuya Erin Krishnaswamy and published by . This book was released on 1999 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Much experimental research has been performed in the equilibrium regime on individual quantum dots and quantum point contacts (QPCs). The focus of the research presented here is electron transport in the nonequilibrium regime in coupled quantum dot and QPC systems fabricated on AlGaAs/GaAs material using the split gate technique. Near equilibrium magnetoconductance measurements were performed on a quantum dot and a QPC. Oscillations were seen in the conductance of the sensor which corresponded to Aharonov-Bohm oscillations in the quantum dot, to our knowledge the first such observation. Sudden jumps in the conductance of the QPC were observed under certain gate biases and under certain magnetic fields. When the gate biases and magnetic field were held constant and the conductance was observed over time, switching was observed with the form of a random telegraph signal (RTS). RTS switching is usually attributed to charging of a single impurity. However, in this case switching may have been due to tunneling via edge states in the dot. Nonequilibrium transport in single quantum dots was investigated. A knee or kink was observed in the current-voltage characteristics of two dots on different material. The bias conditions under which the knee occurred point to electron heating as the physical mechanism for the observed behavior. However, the data can not be fit accurately over all bias ranges with an energy balance hot electron model. Modifications to the model are needed to accurately represent the devices studied here. Finally, the effect of nonlinear transport through a one dimensional (1D) QPC on the equilibrium conductance of an adjacent OD quantum dot was explored. This was the first attempt to observe Coulomb drag between a OD and 1D system. It was observed that the equilibrium conductance peaks in the quantum dot were broadened as the current in the QPC increased. This apparent electron heating effect in the dot can be explained by a simple ballistic phonon model. However, reasonable phase coherence times can be estimated from peak fitting using a Breit- Wigner formula which points to a Coulomb interaction. More detailed numerical calculations should illuminate the dominant scattering processes.
Download or read book Quantum Dots Handbook written by Eva Murphy and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives innovative and resourceful techniques for calculating the optical and transport characteristics of quantum dot structures. The book deals with the importance of transport and electronic characteristics of quantum dot structures. This is a collaborative initiative, providing primary research such as the ones conducted in physics, chemistry, and material science. This book serves as a source of reference for this field.
Download or read book Electron Transport in Quantum Dots written by Jonathan P. Bird and published by Springer Science & Business Media. This book was released on 2013-11-27 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: When I was contacted by Kluwer Academic Publishers in the Fall of 200 I, inviting me to edit a volume of papers on the issue of electron transport in quantum dots, I was excited by what I saw as an ideal opportunity to provide an overview of a field of research that has made significant contributions in recent years, both to our understanding of fundamental physics, and to the development of novel nanoelectronic technologies. The need for such a volume seemed to be made more pressing by the fact that few comprehensive reviews of this topic have appeared in the literature, in spite of the vast activity in this area over the course of the last decade or so. With this motivation, I set out to try to compile a volume that would fairly reflect the wide range of opinions that has emerged in the study of electron transport in quantum dots. Indeed, there has been no effort on my part to ensure any consistency between the different chapters, since I would prefer that this volume instead serve as a useful forum for the debate of critical issues in this still developing field. In this matter, I have been assisted greatly by the excellent series of articles provided by the different authors, who are widely recognized as some of the leaders in this vital area of research.
Download or read book The Non Equilibrium Green s Function Method for Nanoscale Device Simulation written by Mahdi Pourfath and published by Springer. This book was released on 2014-07-05 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: For modeling the transport of carriers in nanoscale devices, a Green-function formalism is the most accurate approach. Due to the complexity of the formalism, one should have a deep understanding of the underlying principles and use smart approximations and numerical methods for solving the kinetic equations at a reasonable computational time. In this book the required concepts from quantum and statistical mechanics and numerical methods for calculating Green functions are presented. The Green function is studied in detail for systems both under equilibrium and under nonequilibrium conditions. Because the formalism enables rigorous modeling of different scattering mechanisms in terms of self-energies, but an exact evaluation of self-energies for realistic systems is not possible, their approximation and inclusion in the quantum kinetic equations of the Green functions are elaborated. All the elements of the kinetic equations, which are the device Hamiltonian, contact self-energies and scattering self-energies, are examined and efficient methods for their evaluation are explained. Finally, the application of these methods to study novel electronic devices such as nanotubes, graphene, Si-nanowires and low-dimensional thermoelectric devices and photodetectors are discussed.
Download or read book Transport in Nanostructures written by David K. Ferry and published by Cambridge University Press. This book was released on 2009-08-20 with total page 671 pages. Available in PDF, EPUB and Kindle. Book excerpt: The advent of semiconductor structures whose characteristic dimensions are smaller than the mean free path of carriers has led to the development of novel devices, and advances in theoretical understanding of mesoscopic systems or nanostructures. This book has been thoroughly revised and provides a much-needed update on the very latest experimental research into mesoscopic devices and develops a detailed theoretical framework for understanding their behaviour. Beginning with the key observable phenomena in nanostructures, the authors describe quantum confined systems, transmission in nanostructures, quantum dots, and single electron phenomena. Separate chapters are devoted to interference in diffusive transport, temperature decay of fluctuations, and non-equilibrium transport and nanodevices. Throughout the book, the authors interweave experimental results with the appropriate theoretical formalism. The book will be of great interest to graduate students taking courses in mesoscopic physics or nanoelectronics, and researchers working on semiconductor nanostructures.
Download or read book Low Temperature Transport Through a Quantum Dot the Anderson Model Out of Equilibrium written by and published by . This book was released on 1993 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: The infinite-U Anderson model is applied to non-equilibrium transport through a quantum dot containing two spin levels weakly coupled to two leads. At low temperatures, the Kondo peak in the equilibrium density of states is split upon the application of a voltage bias. The split peaks, one at the chemical potential of each lead, are suppressed by non-equilibrium dissipation. In a magnetic field, the Kondo peaks shift away from the chemical potentials by the Zeeman energy, leading to an observable peak in the differential conductance when the non-equilibrium bias equals the Zeeman energy. Infinite-U Anderson model, Kondo peak, Zeeman energy, Low-temperature transport through a quantum dot, Kondo effect.
Download or read book Nonequilibrium Quantum Transport Physics In Nanosystems Foundation Of Computational Nonequilibrium Physics In Nanoscience And Nanotechnology written by Felix A Buot and published by World Scientific. This book was released on 2009-08-05 with total page 838 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the first comprehensive treatment of discrete phase-space quantum mechanics and the lattice Weyl-Wigner formulation of energy band dynamics, by the originator of these theoretical techniques. The author's quantum superfield theoretical formulation of nonequilibrium quantum physics is given in real time, without the awkward use of artificial time contour employed in previous formulations. These two main quantum theoretical techniques combine to yield general (including quasiparticle-pairing dynamics) and exact quantum transport equations in phase-space, appropriate for nanodevices. The derivation of transport formulas in mesoscopic physics from the general quantum transport equations is also treated. Pioneering nanodevices are discussed in the light of the quantum-transport physics equations, and an in-depth treatment of the physics of resonant tunneling devices is given. Operator Hilbert-space methods and quantum tomography are discussed. Discrete phase-space quantum mechanics on finite fields is treated for completeness and by virtue of its relevance to quantum computing. The phenomenological treatment of evolution superoperator and measurements is given to help clarify the general quantum transport theory. Quantum computing and information theory is covered to demonstrate the foundational aspects of discrete quantum dynamics, particularly in deriving a complete set of multiparticle entangled basis states.
Download or read book Fingerprints in the Optical and Transport Properties of Quantum Dots written by Ameenah Al-Ahmadi and published by BoD – Books on Demand. This book was released on 2012-06-13 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book "Fingerprints in the optical and transport properties of quantum dots" provides novel and efficient methods for the calculation and investigating of the optical and transport properties of quantum dot systems. This book is divided into two sections. In section 1 includes ten chapters where novel optical properties are discussed. In section 2 involve eight chapters that investigate and model the most important effects of transport and electronics properties of quantum dot systems This is a collaborative book sharing and providing fundamental research such as the one conducted in Physics, Chemistry, Material Science, with a base text that could serve as a reference in research by presenting up-to-date research work on the field of quantum dot systems.
Download or read book Electronic Structure and Transport Properties of Quantum Dots written by Alev Devrim Güçlü and published by . This book was released on 2003 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nonlinear and Nonequilibrium Dynamics of Quantum Dot Optoelectronic Devices written by Benjamin Lingnau and published by Springer. This book was released on 2015-12-14 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis sheds light on the unique dynamics of optoelectronic devices based on semiconductor quantum-dots. The complex scattering processes involved in filling the optically active quantum-dot states and the presence of charge-carrier nonequilibrium conditions are identified as sources for the distinct dynamical behavior of quantum-dot based devices. Comprehensive theoretical models, which allow for an accurate description of such devices, are presented and applied to recent experimental observations. The low sensitivity of quantum-dot lasers to optical perturbations is directly attributed to their unique charge-carrier dynamics and amplitude-phase-coupling, which is found not to be accurately described by conventional approaches. The potential of quantum-dot semiconductor optical amplifiers for novel applications such as simultaneous multi-state amplification, ultra-wide wavelength conversion, and coherent pulse shaping is investigated. The scattering mechanisms and the unique electronic structure of semiconductor quantum-dots are found to make such devices prime candidates for the implementation of next-generation optoelectronic applications, which could significantly simplify optical telecommunication networks and open up novel high-speed data transmission schemes.
Download or read book Low Dimensional Systems written by Tobias Brandes and published by Springer. This book was released on 2014-03-12 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental progress over the past few years has made it possible to test a n- ber of fundamental physical concepts related to the motion of electrons in low dimensions. The production and experimental control of novel structures with typical sizes in the sub-micrometer regime has now become possible. In parti- lar, semiconductors are widely used in order to con?ne the motion of electrons in two-dimensional heterostructures. The quantum Hall e?ect was one of the ?rst highlights of the new physics that is revealed by this con?nement. In a further step of the technological development in semiconductor-heterostructures, other arti?cial devices such as quasi one-dimensional ‘quantum wires’ and ‘quantum dots’ (arti?cial atoms) have also been produced. These structures again di?er very markedly from three- and two-dimensional systems, especially in relation to the transport of electrons and the interaction with light. Although the technol- ical advances and the experimental skills connected with these new structures are progressing extremely fast, our theoretical understanding of the physical e?ects (such as the quantum Hall e?ect) is still at a very rudimentary level. In low-dimensional structures, the interaction of electrons with one another and with other degrees of freedoms such as lattice vibrations or light gives rise to new phenomena that are very di?erent from those familiar in the bulk ma- rial. The theoretical formulation of the electronic transport properties of small devices may be considered well-established, provided interaction processes are neglected.
Download or read book Non Equilibrium Carriers in Type II Quantum Dots written by A. Shik and published by . This book was released on 2001 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: The spatial distribution and recombination of nonequilibrium electrons and holes in a system of type-II quantum dots is considered theoretically. In this system contrary to the well known type-I quantum dots system one type of carrier is confined to the dot whereas the other type is localized in a Coulomb potential well outside the dot. The alters the recombination processes dramatically and results in new intensity and temperature dependencies in the photoconductivity. Possible device applications of type-II quantum dots, in particular for photovoltaic structures, are discussed.
Download or read book Quantum Dot Heterostructures written by Dieter Bimberg and published by John Wiley & Sons. This book was released on 1999-03-17 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: Da die Nachfrage nach immer schnelleren und kleineren Halbleiterbauelementen stetig wächst, sind Quanten-Dots und -Pyramiden rasant in den Mittelpunkt der Halbleiterforschung gerückt. Dieses Buch vermittelt einen umfassenden Überblick über den aktuellen Forschungsstand auf diesem Gebiet. Behandelt werden u.a. Fragen, wie Strukturen aufgebaut, wie sie charakterisiert werden und wie sie die Leistungsfähigkeit der Bauelemente bestimmen. (11/98)
