Download or read book Optical Spectroscopy of Laterally Spaced InAs GaAs Quantum Dot Molecules written by Shilpa Sanwlani and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade, potential device applications have fueled an extensive effort to fabricate lateral arrays of quantum dots (QDs) with specific dot densities, spacings and size distributions. An essential element for the further development of QD devices with new functionalities is the introduction of controllable quantum coupling between two or more QDs in such an array. Tunable quantum coupling between vertically stacked InAs QDs has been demonstrated, with the coupling mediated by coherent tunneling and tunable with a static electric field. While these studies have revealed that the spatial arrangement of QDs can lead to remarkable effects, it will be impossible to scale vertical coupling to a large number of QDs. Investigations of lateral quantum coupling have been slower to develop, however, because special growth protocols are required and the ability to independently tune the luminescence energy of separate QDs is lost. Spectroscopy of single pairs of laterally separated QDs is required to resolve the signatures of quantum coupling from inhomogeneously broadened ensemble spectra. Laterally-coupled quantum dots require modified sample preparation methods to isolate single pairs of QDs and apply electric fields that tune the relative energies of the two dots. The electric field must be applied along the surface of the sample, perpendicular to the growth direction. To apply this lateral field, we use interdigitated electrodes patterned onto the sample surface with photolithography and metal deposition. Electrical connections are made to each of the interdigitated top contacts as well as to an ohmic back contact. This three-terminal arrangement makes it possible to independently control both the relative energies of the dots and the charging of the QDs. We present photoluminescence spectra of laterally coupled QDs whose coupling and charge states are tuned with this three-terminal arrangement. We further discuss the implications and opportunities for control of quantum coupling in laterally-scalable architectures.
Download or read book Optical Spectroscopy of InAs GaAs Quantum Dot Molecules written by Shilpa Sanwlani Arora and published by . This book was released on 2011-11 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Structural Optical and Spectral Behaviour of InAs based Quantum Dot Heterostructures written by Saumya Sengupta and published by Springer. This book was released on 2017-08-04 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explores the effects of growth pause or ripening time on the properties of quantum dots(QDs). It covers the effects of post-growth rapid thermal annealing (RTA) treatment on properties of single layer QDs. The effects of post-growth rapid thermal annealing (RTA) treatment on properties of single layer QDs are discussed. The book offers insight into InAs/GaAs bilayer QD heterostructures with very thin spacer layers and discusses minimum spacer thickness required to grow electronically coupled bilayer QD heterostructures. These techniques make bilayer QD heterostructures a better choice over the single layer and uncoupled multilayer QD heterostructure. Finally, the book discusses sub-monolayer (SML) growth technique to grow QDs. This recent technique has been proven to improve the device performance significantly. The contents of this monograph will prove useful to researchers and professionals alike.
Download or read book Lateral Alignment of Epitaxial Quantum Dots written by Oliver G. Schmidt and published by Springer Science & Business Media. This book was released on 2007-08-17 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the full range of possible strategies for laterally aligning self-assembled quantum dots on a substrate surface, beginning with pure self-ordering mechanisms and culminating with forced alignment by lithographic positioning. The text addresses both short- and long-range ordering phenomena and introduces future high integration of single quantum dot devices on a single chip. Contributions by well-known experts ensure that all relevant quantum-dot heterostructures are elucidated from diverse perspectives.
Download or read book Semiconductor Quantum Dots written by Yasuaki Masumoto and published by Springer Science & Business Media. This book was released on 2002-05-28 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: Growth of Self Organized Quantum Dots / J.-S. Lee / - Excitonic Structures and Optical Properties of Quantum Dots / Toshihide Takagahara / - Electron-Phonon Interactions in Semiconductor Quantum Dots / Toshihide Takagahara / - Micro-Imaging and Single Dot Spectroscopy of Self Assembled Quantum Dots / Mitsuru Sugisaki / - Persistent Spectral Hole Burning in Semiconductor Quantum Dots / Yasuaki Masumoto / - Dynamics of Carrier Relaxation in Self Assembled Quantum Dots / Ivan V. Ignatiev, Igor E. Kozin / - Resonant Two-Photon Spectroscopy of Quantum Dots / Alexander Baranov / - Homogeneous Width of Confined Excitons in Quantum Dots - Experimental / Yasuaki Masumoto / - Theory of Exciton Dephasing in Semiconductor Quantum Dots / Toshihide Takagahara / - Excitonic Optical Nonlinearity and Weakly Correlated Exciton-Pair States / Selvakumar V. Nair, Toshihide Takagahara / - Coulomb Effects in the Optical Spectra of Highly Excited Semiconductor Quantum Dots / Selvakumar V. Nair / - Device ...
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 Exploring Single Hole States in InAs GaAs Quantum Dots and Quantum Dot Molecules Under 2 D Electric Fields written by Xiangyu Ma and published by . This book was released on 2019 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: InAs/GaAs quantum dots (QDs) and quantum dot molecules (QDMs) are self-assembled semiconductor nanostructures that can trap a single electron or hole in a 3-D potential-well. Grown by molecular beam epitaxy (MBE), they have excellent optical qualities that can be used in applications for quantum information processing and quantum computing. Specifically, hole spins in a single QD/QDM have longer decoherence time than electron spins due to the lack of hyperfine interaction, making hole spins a great qubit candidate. However, many challenges such as QD growth, device integration, and spin manipulation inhibit the scalability of a hole-spin-based quantum information platform. A deeper understanding of the hole spin physics and the QD/QDM material system is needed to advance device engineering opportunities.
Download or read book Quantum Dots Fundamentals Applications and Frontiers written by Bruce A. Joyce and published by Springer Science & Business Media. This book was released on 2006-03-30 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains papers delivered at a NATO Advanced Research Workshop and provides a broad introduction to all major aspects of quantum dot structures. Such structures have been produced for studies of basic physical phenomena, for device fabrication and, on a more speculative level, have been suggested as components of a solid-state realization of a quantum computer. The book is structured so that the reader is introduced to the methods used to produce and control quantum dots, followed by discussions of their structural, electronic, and optical properties. It concludes with examples of how their optical properties can be used in practical devices, including lasers and light-emitting diodes operating at the commercially important wavelengths of 1.3 Am and 1.55 Am."
Download or read book Optical Spectroscopy of InGaAs GaAs Self Assembled Quantum Dots written by Paul William Fry and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Self Assembled InGaAs GaAs Quantum Dots written by and published by Academic Press. This book was released on 1999-03-29 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is concerned with the crystal growth, optical properties, and optical device application of the self-formed quantum dot, which is one of the major current subjects in the semiconductor research field.The atom-like density of states in quantum dots is expected to drastically improve semiconductor laser performance, and to develop new optical devices. However, since the first theoretical prediction for its great possibilities was presented in 1982, due to the difficulty of their fabrication process. Recently, the advent of self-organized quantum dots has made it possible to apply the results in important optical devices, and further progress is expected in the near future.The authors, working for Fujitsu Laboratories, are leading this quantum-dot research field. In this volume, they describe the state of the art in the entire field, with particular emphasis on practical applications.
Download or read book Bulletin of the STEFAN UNIVERSITY Semiconductor Science and Technology 1998 ISSN 1098 1632 written by Editors of the Stefan University Press and published by Stefan University Press. This book was released on 1998-09-07 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bulletin of the STEFAN UNIVERSITY: Semiconductor Science and Technology—1998; ISSN: 1098-1632.: Stefan Frontier Conferences (Frontier Science Research Conferences--FSRC); La Jolla, California, September 7-11, 1998; @1998, The Stefan University Press
Download or read book Growth Spectroscopy and Quantum Optics of Self assembled Quantum Dot Molecules written by Brian D. Gerardot and published by . This book was released on 2004 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since their inception, semiconductor quantum dots (QDs) have attracted much attention due to properties which are analogous with individual atoms. In addition to classical applications, novel applications have been identified which exploit the strong confinement of both electrons and holes in self-assembled QDs. This artificial atom analogy can be extended to artificial molecules by coupling two neighboring quantum dots. This single quantum system has been proposed for entangled photon pair emission and two bit or quantum bit gate operations. This thesis focuses on self-assembled InAs/GaAs QD molecules, which have good optical quality and tunable electronic and optical properties.
Download or read book Coherent Optical Spectroscopy and Manipulation of GaAs Quantum Dots written by Gang Chen and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Barrier Layer on Optical and Electronic Properties of Quantum Dot Molecules written by Prasoon Pancholi and published by ProQuest. This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, it was suggested that the performance of nanostructure-based optoelectronic devices, in particular quantum dot-based devices, may be enhanced when the active region of the device consists of dots that are coupled laterally and/or vertically. The electronic coupling between the dots provides a new degree of freedom in engineering the electronic bandstructure of the nanostructures. For example, strong electronic coupling between two dots defines a new entity, known as a quantum dot molecule (QDM). We provide in this thesis a comparative theoretical and experimental study of structures consisting of two layers of vertically coupled InAs/GaAs QDs, grown by molecular beam epitaxy on (001) GaAs substrates, in which the GaAs barrier layer thickness was varied between 4 and 10 nm, thus insuring very strong coupling between the dot layers and the existence of "molecule-like" behavior. Theoretically, to understand the nature of the electronic and optical properties of the self-assembled dots and molecules, we determined the strain distribution in the dots. The strain effects were included via the deformation potential theory in an eight-band k p model to calculate the respective electronic band structures. Our experimental investigations of the optical and structural properties of QDM structures confirm the formation of QDMs with energy splittings that agree well with the results of our calculations.
Download or read book Raman Spectroscopy of InAs GaAs Quantum Dots Patterned by Nano indentation written by Lindsay K. Hussey and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Patterns of InAs/GaAs quantum dots (QDs) grown by the combination of nanoindentation technique and molecular beam epitaxy were studied. The resulting QDs tend to preferentially nucleate on indented areas rather than other regions. We studied the strain on the indentations, regions surrounding the indents, and non-indented areas. The QD LO mode for the patterned areas shifts by 7 cm-1 when compared to the non-patterned area. The biaxial strain in the indented areas producing this shift is four times larger than that in non-indented areas, explaining the QD preferential formation within these areas. This larger strain suggests that QDs on the indentations can be formed by depositing a smaller InAs amount than that required to form QDs on non-indented areas, thus obtaining QDs only on the pattern.
Download or read book Modulation of the Optical Absorption in Self Organized InAs GaAs Quantum Dots written by P. N. Brunkov and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Capacitance and photocurrent spectroscopy are used to investigate a Schottky barrier structure containing a single layer of self-organized InA/ GaAs quantum dots. We show that applying a bias to the structure it is possible to change the electron occupation of the dot levels. This in turns is used for controlling the intensity of the light absorbed by the dots and proposed as a novel way for realizing optical modulators operating in the infrared (^ 1.1 micrometer) wavelength range.
Download or read book Optical Spectroscopy of InGaAs GaAs Coupled Quantum Dots written by Michael Reimer and published by . This book was released on 2004 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:
