Download or read book Resonant Tunneling Self Assembled Quantum Dots for Memory Elements written by and published by . This book was released on 1999 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two main research topics were studied during this period: (1) Research on buried strain induced quantum dots (SIQDs) generated by self assembling quantum dot (QDs) layers. We investigated here a new type of quantum dots which are generated by the lateral band gap modulation of a quantum well GaAs/AlGaAs induced by a buried layer of self assembled quantum dots. Such SIQDs allow to move the OD confinement regime into the red region of the spectrum. The confinement energies for these SIQDs are function of the distance between the QDs layer and the QW and on the thickness of the QW. They also allow for a greater flexibility for integrating quantum dot devices in device structures. To this end, we have developed an exciton storage device based on quantum dot structures. The device uses pairs of SIQDs and QDs to store the exciton dissociated as an electron hole pair under an internal electric field. The stored e-h pair is restored as an exciton by applying a bias to the device. This method allows for exciton lifetimes of several seconds i.e., more than a billion times the lifetimes of excitons in normal QDs.
Download or read book Self Assembled Quantum Dots written by Zhiming M Wang and published by Springer Science & Business Media. This book was released on 2007-11-29 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: This multidisciplinary book provides up-to-date coverage of carrier and spin dynamics and energy transfer and structural interaction among nanostructures. Coverage also includes current device applications such as quantum dot lasers and detectors, as well as future applications to quantum information processing. The book will serve as a reference for anyone working with or planning to work with quantum dots.
Download or read book Molecular Nanowires and Other Quantum Objects written by Alexandre S. Alexandrov and published by Springer Science & Business Media. This book was released on 2004-04-30 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a growing understanding that the progress of the conventional silicon technology will reach its physical, engineering and economic limits in near future. This fact, however, does not mean that progress in computing will slow down. What will take us beyond the silicon era are new nano-technologies that are being pursued in university and corporate laboratories around the world. In particular, molecular switching devices and systems that will self-assemble through molecular recognition are being designed and studied. Many labora tories are now testing new types of these and other reversible switches, as well as fabricating nanowires needed to connect circuit elements together. But there are still significant opportunities and demand for invention and discovery be fore nanoelectronics will become a reality. The actual mechanisms of transport through molecular quantum dots and nanowires are of the highest current ex perimental and theoretical interest. In particular, there is growing evidence that both electron-vibron interactions and electron-electron correlations are impor tant. Further progress requires worldwide efforts of trans-disciplinary teams of physicists, quantum chemists, material and computer scientists, and engineers.
Download or read book Research on Self Assembling Quantum Dots written by and published by . This book was released on 1995 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: We summarize the studies done under this contract by listing the main accomplishments in the last 6 years. We started this research by fabricating arrays of antidots in a modulation doped FET structure using a focused ion beam technology. The unique transport properties in these antidot arrays were also studied. We extended the focused ion beam technology to the fabrication of zero dimensional resonant tunneling diodes arid quantum wires fabricated using an insitu regrowth technique. We then switched the research to the growth and studies of self assembled nanostructures in the area of lateral superlattice growth and self assembling of quantum wire arrays, we have demonstrated MBE grown AiAs-GaAs lateral superlattice using transmission electron microscopy (TEM). We improved these self assembled lateral superlattices by growing the "serpentine superlattice" (SSL) using MIBE. The SSL produces directly an array of quantum wires over a large wafer area. Using TEM1 we were able to demonstrate AiAS-GaAs self assembled quantum wire arrays with adjustable dimensions. Optical studies of these self assembled quantum wires using polarized photoluminescence and photoluminescence excitation spectroscopy showed polarization effects that are associated with the ID character of the structure. A quantum wire laser using the SSL growth method was then fabricated. As expected from the 1 D character of the structure, the quantum wire lasers shows large gain an isotropy at temperatures up to 150 0K. in a second phase of this contract we turned our efforts to the fabrication and studies of self assembled quantum dots. We first demonstrated a method for producing InAs-GasAs self assembled quantum dots (SAD) using MBE. (AN).
Download or read book Quantum Dots written by Peter A. Ling and published by Nova Publishers. This book was released on 2005 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: A quantum dot is a particle of matter so small that the addition or removal of an electron changes its properties in some useful way. All atoms are quantum dots, but multi-molecular combinations can have this characteristic. In biochemistry, quantum dots are called redox groups. In nanotechnology, they are called quantum bits or qubits. Quantum dots typically have dimensions measured in nanometers, where one nanometer is 10-9 meter or a millionth of a millimetre. The fields of biology, chemistry, computer science, and electronics are all of interest to researchers in nanotechnology. Other applications of quantum dots include nanomachines, neural networks, and high-density memory or storage media. Research is being carried out on nano-crystals, self-assembled dots, and gated structures. This book presents leading-edge research from around the world.
Download or read book 2000 IEEE International Symposium on Compound Semiconductors written by IEEE Electron Devices Society and published by IEEE Standards Office. This book was released on 2000 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text constitutes the proceedings from the 25th IEEE International Symposium on Compound Semiconductors, which took place in 2000. Topics covered include emitter science and technology, heterostructure devices and quantum effect materials and devices.
Download or read book Time Resolved Electronic Relaxation Processes in Self Organized Quantum Dots written by and published by . This book was released on 2005 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors have performed a comprehensive set of experiments on the dynamics of electrons and holes in semiconductor quantum dots, and a complete picture of the dynamics as a function of carrier density and temperature has emerged. Specifically, they have used two- and three-pulse femtosecond differential transmission spectroscopy to study the dependence of quantum dot carrier dynamics on temperature. At low temperatures and densities, the rates for relaxation between the quantum dot confined states and for capture from the barrier region into the various dot levels could be directly determined. For electron-hole pairs generated directly in the quantum dot excited state, relaxation is dominated by electron-hole scattering, and occurs on a 5-ps time scale. Capture times from the barrier into the quantum dot are on the order of 2 ps (into the excited state) and 10 ps (into the ground state). The phonon bottleneck was clearly observed in low-density capture experiments, and the conditions for its observation (namely, the suppression of electron-hole scattering for non-geminately captured electrons) were determined. As temperature increases beyond about 100 K, the dynamics become dominated by the reemission of carriers from the lower dot levels due to the large density of states in the wetting layer and barrier region. Measurements of the gain dynamics show fast (130-fs) gain recovery due to intradot carrier-carrier scattering, and picosecond-scale capture. Direct measurement of the transparency density versus temperature shows the dramatic effect of carrier reemission for the quantum dots to thermally activated scattering. The carrier dynamics at elevated temperatures are thus strongly dominated by the high density of the high-energy continuum states relative to the dot-confined levels. Deleterious hot carrier effects can be suppressed in quantum dot lasers by resonant tunneling injection.
Download or read book Trends in Quantum Dots Research written by Peter A. Ling and published by Nova Publishers. This book was released on 2005 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: A quantum dot is a particle of matter so small that the addition or removal of an electron changes its properties in some useful way. All atoms are quantum dots, but multi-molecular combinations can have this characteristic. In biochemistry, quantum dots are called redox groups. In nanotechnology, they are called quantum bits or qubits. Quantum dots typically have dimensions measured in nanometres, where one nanometre is 10-9 meter or a millionth of a millimetre. The fields of biology, chemistry, computer science, and electronics are all of interest to researchers in nanotechnology. Other applications of quantum dots include nanomachines, neural networks, and high-density memory or storage media. Research is being carried out on nano-crystals, self-assembled dots, and gated structures. This book presents leading-edge research from around the world.
Download or read book Self Organized Quantum Dots for Memories written by Tobias Nowozin and published by Springer. This book was released on 2013-11-27 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today’s semiconductor memory market is divided between two types of memory: DRAM and Flash. Each has its own advantages and disadvantages. While DRAM is fast but volatile, Flash is non-volatile but slow. A memory system based on self-organized quantum dots (QDs) as storage node could combine the advantages of modern DRAM and Flash, thus merging the latter’s non-volatility with very fast write times. This thesis investigates the electronic properties of and carrier dynamics in self-organized quantum dots by means of time-resolved capacitance spectroscopy and time-resolved current measurements. The first aim is to study the localization energy of various QD systems in order to assess the potential of increasing the storage time in QDs to non-volatility. Surprisingly, it is found that the major impact of carrier capture cross-sections of QDs is to influence, and at times counterbalance, carrier storage in addition to the localization energy. The second aim is to study the coupling between a layer of self-organized QDs and a two-dimensional hole gas (2DHG), which is relevant for the read-out process in memory systems. The investigation yields the discovery of the many-particle ground states in the QD ensemble. In addition to its technological relevance, the thesis also offers new insights into the fascinating field of nanostructure physics.
Download or read book Molecular Nanowires and Other Quantum Objects written by A. S. Alexandrov and published by Springer. This book was released on 2004-06-02 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a growing understanding that the progress of the conventional silicon technology will reach its physical, engineering and economic limits in about a decade. What will take us beyond 2010 are new molecular and other nanotechnologies that require the efforts of trans-disciplinary teams of physicists, quantum chemists, material and computer scientists, and engineers. This volume represents a unique collection of interdisciplinary review and original papers by experts in molecular nanowires, carbon nanotubes, mesoscopic super- and semiconductors, and theorists in the field of strongly correlated electrons and phonons. Topics include molecular nanojunctions and electronics, mesoscale semiconductors and superconductors, carbon nanotubes, low dimensional conductors, polarons and strongly-correlated electrons in nanoobjects, quantum theory of nanoscale, and new techniques for making nano and mesoscopic sensors and detectors.
Download or read book Capture and Relaxation in Self Assembled Semiconductor Quantum Dots written by Robson Ferreira and published by Morgan & Claypool Publishers. This book was released on 2016-02-23 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is an overview of different models and mechanisms developed to describe the capture and relaxation of carriers in quantum-dot systems. Despite their undisputed importance, the mechanisms leading to population and energy exchanges between a quantum dot and its environment are not yet fully understood. The authors develop a first-order approach to such effects, using elementary quantum mechanics and an introduction to the physics of semiconductors. The book results from a series of lectures given by the authors at the Master’s level.
Download or read book Electron Tunneling Properties of Self assembled Monolayers and Quantum Dots written by Pao-hung Lin and published by . This book was released on 2000 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Graphene Science Handbook Six Volume Set written by Mahmood Aliofkhazraei and published by CRC Press. This book was released on 2016-04-26 with total page 3379 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene is the strongest material ever studied and can be an efficient substitute for silicon. This six-volume handbook focuses on fabrication methods, nanostructure and atomic arrangement, electrical and optical properties, mechanical and chemical properties, size-dependent properties, and applications and industrialization. There is no other major reference work of this scope on the topic of graphene, which is one of the most researched materials of the twenty-first century. The set includes contributions from top researchers in the field and a foreword written by two Nobel laureates in physics. Volumes in the set: K20503 Graphene Science Handbook: Mechanical and Chemical Properties (ISBN: 9781466591233) K20505 Graphene Science Handbook: Fabrication Methods (ISBN: 9781466591271) K20507 Graphene Science Handbook: Electrical and Optical Properties (ISBN: 9781466591318) K20508 Graphene Science Handbook: Applications and Industrialization (ISBN: 9781466591332) K20509 Graphene Science Handbook: Size-Dependent Properties (ISBN: 9781466591356) K20510 Graphene Science Handbook: Nanostructure and Atomic Arrangement (ISBN: 9781466591370)
Download or read book Capture and Relaxation in Self Assembled Semiconductor Quantum Dots written by R Ferreira and published by Myprint. This book was released on 2015-12-18 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Semiconductors written by and published by . This book was released on 2005 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Classical and Quantum Information written by Dan C. Marinescu and published by Academic Press. This book was released on 2011-01-07 with total page 745 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new discipline, Quantum Information Science, has emerged in the last two decades of the twentieth century at the intersection of Physics, Mathematics, and Computer Science. Quantum Information Processing is an application of Quantum Information Science which covers the transformation, storage, and transmission of quantum information; it represents a revolutionary approach to information processing. Classical and Quantum Information covers topics in quantum computing, quantum information theory, and quantum error correction, three important areas of quantum information processing. Quantum information theory and quantum error correction build on the scope, concepts, methodology, and techniques developed in the context of their close relatives, classical information theory and classical error correcting codes. - Presents recent results in quantum computing, quantum information theory, and quantum error correcting codes - Covers both classical and quantum information theory and error correcting codes - The last chapter of the book covers physical implementation of quantum information processing devices - Covers the mathematical formalism and the concepts in Quantum Mechanics critical for understanding the properties and the transformations of quantum information
Download or read book Nanoscale Science and Technology written by Robert Kelsall and published by John Wiley & Sons. This book was released on 2005-11-01 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanotechnology is a vital new area of research and development addressing the control, modification and fabrication of materials, structures and devices with nanometre precision and the synthesis of such structures into systems of micro- and macroscopic dimensions. Future applications of nanoscale science and technology include motors smaller than the diameter of a human hair and single-celled organisms programmed to fabricate materials with nanometer precision. Miniaturisation has revolutionised the semiconductor industry by making possible inexpensive integrated electronic circuits comprised of devices and wires with sub-micrometer dimensions. These integrated circuits are now ubiquitous, controlling everything from cars to toasters. The next level of miniaturisation, beyond sub-micrometer dimensions into nanoscale dimensions (invisible to the unaided human eye) is a booming area of research and development. This is a very hot area of research with large amounts of venture capital and government funding being invested worldwide, as such Nanoscale Science and Technology has a broad appeal based upon an interdisciplinary approach, covering aspects of physics, chemistry, biology, materials science and electronic engineering. Kelsall et al present a coherent approach to nanoscale sciences, which will be invaluable to graduate level students and researchers and practising engineers and product designers.
