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Ultrafast Carrier And Gain Dynamics In Strongly Confined Semiconductor Quantum Dots
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Book Synopsis Ultrafast Carrier and Gain Dynamics in Strongly Confined Semiconductor Quantum Dots by : Harald Willi Giessen
Download or read book Ultrafast Carrier and Gain Dynamics in Strongly Confined Semiconductor Quantum Dots written by Harald Willi Giessen and published by . This book was released on 1995 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Quantum Dots by :
Download or read book Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Quantum Dots written by and published by . This book was released on 1998 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-dimensional semiconductors have attracted great interest due to the potential for tailoring their linear and nonlinear optical properties over a wide-range. Semiconductor nanocrystals (NC's) represent a class of quasi-zero-dimensional objects or quantum dots. Due to quantum cordhement and a large surface-to-volume ratio, the linear and nonlinear optical properties, and the carrier dynamics in NC's are significantly different horn those in bulk materials. napping at surface states can lead to a fast depopulation of quantized states, accompanied by charge separation and generation of local fields which significantly modifies the nonlinear optical response in NC's. 3D carrier confinement also has a drastic effect on the energy relaxation dynamics. In strongly confined NC's, the energy-level spacing can greatly exceed typical phonon energies. This has been expected to significantly inhibit phonon-related mechanisms for energy losses, an effect referred to as a phonon bottleneck. It has been suggested recently that the phonon bottleneck in 3D-confined systems can be removed due to enhanced role of Auger-type interactions. In this paper we report femtosecond (fs) studies of ultrafast optical nonlinearities, and energy relaxation and trap ping dynamics in three types of quantum-dot systems: semiconductor NC/glass composites made by high temperature precipitation, ion-implanted NC's, and colloidal NC'S. Comparison of ultrafast data for different samples allows us to separate effects being intrinsic to quantum dots from those related to lattice imperfections and interface properties.
Book Synopsis Ultrafast Carrier Dynamics of InGaAs Quantum Dots in the High Carrier Density Regime by : Kyoungsik Kim
Download or read book Ultrafast Carrier Dynamics of InGaAs Quantum Dots in the High Carrier Density Regime written by Kyoungsik Kim and published by . This book was released on 2004 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Charge Carrier Dynamics and the Development of Optical Gain in Semiconductor Quantum Dots by : Ryan R. Cooney
Download or read book Charge Carrier Dynamics and the Development of Optical Gain in Semiconductor Quantum Dots written by Ryan R. Cooney and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Time-Resolved Electronic Relaxation Processes in Self-Organized Quantum Dots by :
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.
Book Synopsis Semiconductor Quantum Dots by : Yasuaki Masumoto
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 ...
Book Synopsis Semiconductor Quantum Dots by : Ladislaus B nyai
Download or read book Semiconductor Quantum Dots written by Ladislaus B nyai and published by World Scientific. This book was released on 1993 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor Quantum Dots presents an overview of the background and recent developments in the rapidly growing field of ultrasmall semiconductor microcrystallites, in which the carrier confinement is sufficiently strong to allow only quantized states of the electrons and holes. The main emphasis of this book is the theoretical analysis of the confinement induced modifications of the optical and electronic properties of quantum dots in comparison with extended materials. The book develops the theoretical background material for the analysis of carrier quantum-confinement effects, introduces the different confinement regimes for relative or center-of-mass motion quantization of the electron-hole-pairs, and gives an overview of the best approximation schemes for each regime. A detailed discussion of the carrier states in quantum dots is presented and surface polarization instabilities are analyzed, leading to the self-trapping of carriers near the surface of the dots. The influence of spin-orbit coupling on the quantum-confined carrier states is discussed. The linear and nonlinear optical properties of small and large quantum dots are studied in detail and the influence of the quantum-dot size distribution in many realistic samples is outlined. Phonons in quantum dots as well as the influence of external electric or magnetic fields are also discussed. Last but not least the recent developments dealing with regular systems of quantum dots are also reviewed. All things included, this is an important piece of work on semiconductor quantum dots not to be dismissed by serious researchers and physicists.
Book Synopsis Colloidal Quantum Dot Optoelectronics and Photovoltaics by : Gerasimos Konstantatos
Download or read book Colloidal Quantum Dot Optoelectronics and Photovoltaics written by Gerasimos Konstantatos and published by Cambridge University Press. This book was released on 2013-11-07 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: Captures the most up-to-date research in the field, written in an accessible style by the world's leading experts.
Book Synopsis Optics of Semiconductors and Their Nanostructures by : Heinz Kalt
Download or read book Optics of Semiconductors and Their Nanostructures written by Heinz Kalt and published by Springer Science & Business Media. This book was released on 2013-04-09 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years the field of semiconductor optics has been pushed to several extremes. The size of semiconductor structures has shrunk to dimensions of a few nanometers, the semiconductor-light interaction is studied on timescales as fast as a few femtoseconds, and transport properties on a length scale far below the wavelength of light have been revealed. These advances were driven by rapid improvements in both semiconductor and optical technologies and were further facilitated by progress in the theoretical description of optical excitations in semiconductors. This book, written by leading experts in the field, provides an up-to-date introduction to the optics of semiconductors and their nanostructures so as to help the reader understand these exciting new developments. It also discusses recently established applications, such as blue-light emitters, as well as the quest for future applications in areas such as spintronics, quantum information processing, and third-generation solar cells.
Book Synopsis High-speed Properties of 1.55-mum-wavelength Quantum Dot Semiconductor Amplifiers and Comparison with Higher-dimensional Structures by : Aaron John Zilkie
Download or read book High-speed Properties of 1.55-mum-wavelength Quantum Dot Semiconductor Amplifiers and Comparison with Higher-dimensional Structures written by Aaron John Zilkie and published by . This book was released on 2008 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis reports an experimental characterization of the ultrafast gain and refractive index dynamics of a novel InAs/InGaAsP/InP quantum-dot (QD) semiconductor optical amplifier (SOA) operating near 1.55-mum wavelengths, assessing its high-speed performance characteristics for the first time. The thesis also studies the influence of the degree of quantum confinement on the dynamics of SOAs by comparing the zero-dimensional (0-D) QD's dynamics to those in 1-D InAs/InAlGaAs/InP quantum-dash (QDash), and 2-D InGaAsP/InGaAsP/InP quantum-well (QW) SOAs, both of which also operate near 1.55-mum wavelengths, and are made with matching or similar materials and structures. The ultrafast (around 1 ps) and long-lived (up to 2 ns) amplitude and phase dynamics of the SOAs are characterized via advanced heterodyne pump-probe measurements with 150-femtosecond resolution. It is found that the QD SOA has an 80-picosecond amplitude, and 110-picosecond phase recovery lifetime in the gain regime, 4-6 times faster than the QDash and QW recovery lifetimes, as well as reduced ultrafast transients, giving it the best properties for high-speed (>100 Gb/s) all-optical signal processing in the important telecommunications wavelength bands.An impulse response model is developed and used to analyze the dynamics, facilitating a comparison of the gain compression factors, time-resolved linewidth enhancement factors (alpha-factors), and instantaneous dynamic coefficients (two-photon absorption and nonlinear refractive-index coefficients) amongst the three structures. The quantum-dot device is found to have the lowest effective alpha-factor, 2--10, compared to 8--16 in the QW, as well as time-resolved alpha-factors lower than in the QW---promising for reduced-phase-transient operation at high bitrates. Significant differences in the alpha-factors of lasers with the same structure are found, due to the differences between gain changes that are induced optically or through the electrical bias. The relative contributions of stimulated transitions and free-carrier absorption to the total carrier heating dynamics in SOAs of varying dimensionality are also reported for the first time.Examining the QD electroluminescence and linear gain spectra in combination with the carrier dynamics also brings about conclusions on the nature of the quantum confinement, dot energy-level structure, and density of states---aspects of the material that have not been previously well understood.
Book Synopsis Self-Organized Quantum Dots for Memories by : Tobias Nowozin
Download or read book Self-Organized Quantum Dots for Memories written by Tobias Nowozin and published by Springer Science & Business Media. This book was released on 2013-10-01 with total page 163 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.
Book Synopsis Ultrafast carrier dynamics in p doped InGaAs/GaAs quantum dots by : Valentina Cesari
Download or read book Ultrafast carrier dynamics in p doped InGaAs/GaAs quantum dots written by Valentina Cesari and published by . This book was released on 2009 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Excitonic and Vibrational Dynamics in Nanotechnology by : Svetlana Kilina
Download or read book Excitonic and Vibrational Dynamics in Nanotechnology written by Svetlana Kilina and published by CRC Press. This book was released on 2019-10-10 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book investigates QDs and SWCNTs using quantum-chemical calculations that describe intricate details of excited-state phenomena and provides information about the mechanisms that occur on the atomic level and that are extremely difficult, if not impossible, to probe experimentally. It delivers, consistently and coherently, a novel approach to nanomaterials which is promising for today's technologies as well as their future. This approach elegantly overcomes computational difficulties known in the field and shares ways to reach top performance in the description of combined quantum effects of molecular vibrations and exciton formation on realistic-size numerical models. The reader will acquire an understanding of the pioneering methodolo
Book Synopsis Capture and Relaxation in Self-Assembled Semiconductor Quantum Dots by : Robson Ferreira
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 148 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.
Book Synopsis Semiconductor Quantum Dots II: by : Rosa Leon
Download or read book Semiconductor Quantum Dots II: written by Rosa Leon and published by Cambridge University Press. This book was released on 2014-06-05 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book confirms the high level of international interest in understanding and control the properties of semiconductor quantum-dot structures and devices. It highlights the self-assembled (self-forming) type of quantum dots that result from the islanding transition in strained heteroepitaxy of III-V semiconductors. It also features nanocrystals, colloidal dots and biological applications. Technological applications span quantum-dot laser diodes, quantum-dot optical amplifiers, biosensing applications, infrared photodetectors, photovoltaic devices, quantum cellular automata and magnetic semiconductors. It reports the development by researchers at the Johannes Kepler University in Linz of a mid-infrared, vertical cavity surface emitting quantum dot (QD) using the lead salt compounds PbSe and PbEuTe; optical gain and stimulated emission in colloidal quantum dots and the use of quantum dots for optical amplifiers reported by researchers at the National Institute of Standards and Technology in Boulder. Topics include: theory, modeling and simulations; nanocrystals, colloidal dots and biological applications; quantum-dot-based devices and transport studies; carrier dynamics and interactions and energy relaxation and single-dot spectroscopy.
Book Synopsis Nano-Optoelectronics by : Marius Grundmann
Download or read book Nano-Optoelectronics written by Marius Grundmann and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: Traces the quest to use nanostructured media for novel and improved optoelectronic devices. Leading experts - among them Nobel laureate Zhores Alferov - write here about the fundamental concepts behind nano-optoelectronics, the material basis, physical phenomena, device physics and systems.
Book Synopsis Carrier Dynamics in Semiconductor Quantum Dots by : Jörg Siegert
Download or read book Carrier Dynamics in Semiconductor Quantum Dots written by Jörg Siegert and published by . This book was released on 2006 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt:
