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:

Download or read book A Theoretical Study of Carrier Dynamics in Semiconductor Quantum Dots written by Marta Cundin and published by . This book was released on 2004 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Ultrafast Carrier Dynamics in Semiconductor Self assembled Quantum Dots in the Low Carrier Density Regime written by Junji Urayama and published by . This book was released on 2002 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Charge Carrier Dynamics in Nontoxic Semiconductor Quantum Dots written by Alexander Florian Richter and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Surface Effects on Charge Carrier Dynamics in Semiconductor Quantum Dots written by Pooja Tyagi and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Due to the large surface-to-volume ratio of quantum dots, their surface conditions play a significant role in determining their electronic and optical properties. In this thesis, we show that the presence of surface states modifies the optical selection rules in quantum dots and enhances the rate of surface charge trapping. These surface-induced effects have profound impact on the measurement of multiexciton recombination and carrier multiplication processes. Specifically, in transient absorption studies, surface states result in additional decay timescales which may be misattributed to multiexciton recombination processes. Additionally, they lead to large "apparent" carrier multiplication yields even under conditions where it is forbidden by energy conservation. The surface-dependent transient absorption studies presented in this work suggest ways to identify and minimize the undesirable surface-induced signals. Interestingly, surface-induced processes also result in significant electrostatic effects. We show that due to the piezoelectric nature of wurtzite CdSe quantum dots, the strong electric field created by surface charge trapping can drive coherent acoustic phonons in these systems. We further show that the amplitude of this piezoelectric response can be controlled by altering the surface conditions of the quantum dot. Finally, we theoretically investigate the effect of multiple surface layers on carrier localization in nanostructures. We find that in a core/barrier/shell configuration, layered nanostructures offer independent control over electron and hole wave functions. These results suggest design principles for wave function engineering in potential quantum dot applications in light emitting devices, photovoltaics and optical amplification." --

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 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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:

Download or read book Study of Carrier Dynamics in Semiconductor Self assembled Quantum Dots written by 蘇立杰 and published by . This book was released on 2010 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Carrier Dynamics in Electrically Pumped Semiconductor Quantum Dot Amplifiers written by Stephan Schneider and published by . This book was released on 2004 with total page 103 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 Nonequilibrium Carrier Dynamics in Semiconductors written by Marco Saraniti and published by Springer Science & Business Media. This book was released on 2007-12-14 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Nonequilibrium Carrier Dynamics in Semiconductors" is a well-established, specialist conference, held every two years, covering a range of topics of current interest to R&D in semiconductor physics/materials, optoelectronics, nanotechnology, quantum information processing. Papers accepted for publication are selected and peer-reviewed by members of the Program Committee during the conference to ensure both rapid and high-quality processing.

Download or read book Non Equilibrium Dynamics of Semiconductors and Nanostructures written by Kong-Thon Tsen and published by CRC Press. This book was released on 2018-10-03 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: The advent of the femto-second laser has enabled us to observe phenomena at the atomic timescale. One area to reap enormous benefits from this ability is ultrafast dynamics. Collecting the works of leading experts from around the globe, Non-Equilibrium Dynamics of Semiconductors and Nanostructures surveys recent developments in a variety of areas in ultrafast dynamics. In eight authoritative chapters illustrated by more than 150 figures, this book spans a broad range of new techniques and advances. It begins with a review of spin dynamics in a high-mobility two-dimensional electron gas, followed by the generation, propagation, and nonlinear properties of high-amplitude, ultrashort strain solitons in solids. The discussion then turns to nonlinear optical properties of nanoscale artificial dielectrics, optical properties of GaN self-assembled quantum dots, and optical studies of carrier dynamics and non-equilibrium optical phonons in nitride-based semiconductors. Rounding out the presentation, the book examines ultrafast non-equilibrium electron dynamics in metal nanoparticles, monochromatic acoustic phonons in GaAs, and electromagnetically induced transparency in semiconductor quantum wells. With its pedagogical approach and practical, up-to-date coverage, Non-Equilibrium Dynamics of Semiconductors and Nanostructures allows you to easily put the material into practice, whether you are a seasoned researcher or new to the field.

Download or read book Photonics of Quantum dot Nanomaterials and Devices written by Ortwin Hess and published by World Scientific. This book was released on 2012 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1. Introduction to photonic quantum dot nanomaterials and devices. 1.1. Physical properties of quantum dots. 1.2. Active semiconductor gain media. 1.3. Quantum dot lasers. 1.4. Laser cavities -- 2. Theory of quantum dot light-matter dynamics. 2.1. Rate equations. 2.2. Maxwell-Bloch equations. 2.3. Quantum luminescence equations. 2.4. Quantum theoretical description -- 3. Light meets matter I: microscopic carrier effect. 3.1. Dynamics in the active charge carrier plasma. 3.2. Dynamic level hole burning. 3.3. Ultrashort nonlinear gain and index dynamics. 3.4. Conclusion -- 4. Light meets matter II: mesoscopic space-time dynamics. 4.1. Introduction: transverse and longitudinal mode dynamics. 4.2. Influence of the transverse degree of freedom and nano-structuring on nearfield dynamics and spectra. 4.3. Longitudinal modes. 4.4. Coupled space-time dynamics. 4.5. Conclusion -- 5. Performance and characterisation: properties on large time and length scales. 5.1. Introduction. 5.2. Spatial and spectral beam quality. 5.3. Dynamic amplitude phase coupling. 5.4. Conclusion -- 6. Nonlinear pulse propagation in semiconductor quantum dot lasers. 6.1. Dynamic shaping of short optical pulses. 6.2. Nonlinear femtosecond dynamics. 6.3. Conclusion -- 7. High-speed dynamics. 7.1. Mode-locking in multi-section quantum dot lasers. 7.2. Dependence of pulse duration on injection current, bias voltage and device geometry. 7.3. Radio frequency spectra of the emitted light. 7.4. Short-pulse optimisation. 7.5. Conclusion -- 8. Quantum dot random lasers. 8.1. Spatially inhomogeneous semiconductor quantum dot ensembles. 8.2. Coherence properties. 8.3. Random lasing in semiconductor quantum dot ensembles. 8.4. Conclusion -- 9. Coherence properties of quantum dot micro-cavity lasers. 9.1. Introduction. 9.2. Radial signal propagation and coherence trapping. 9.3. Influence of disorder. 9.4. Conclusions

Download or read book Charge Carrier Dynamics in Lead Sulfide Quantum Dot Solids written by Rachel Hoffman Gilmore and published by . This book was released on 2017 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum dots, also called semiconductor nanocrystals, are an interesting class of materials because their band gap is a function of the quantum dot size. Their optical properties are not determined solely by the atomic composition, but may be engineered. Advances in quantum dot synthesis have enabled control of the ensemble size dispersity and the creation of monodisperse quantum dot ensembles with size variations of less than one atomic layer. Quantum dots have been used in a variety of applications including solar cells, light-emitting diodes, photodetectors, and thermoelectrics. In many of these applications, understanding charge transport in quantum dot solids is crucial to optimizing efficient devices. We examine charge transport in monodisperse, coupled quantum dot solids using spectroscopic techniques explained by hopping transport models that provide a complementary picture to device measurements. In our monodisperse quantum dot solids, the site-to-site energetic disorder that comes from size dispersity and the size-dependent band gap is very small and spatial disorder in the quantum dot superlattice often has a greater impact on charge transport. In Chapter 2, we show that improved structural order from self-assembly in monodisperse quantum dots reduces the interparticle spacing and has a greater impact than reduced energetic disorder on increasing charge carrier hopping rates. In Chapter 3, we present temperature-dependent transport measurements that demonstrate again that when energetic disorder is very low, structural changes will dominate the dynamics. We find increasing mobility with decreasing temperature that can be explained by a 1-2 Å contraction in the edge-to-edge nearest neighbor quantum dot spacing. In Chapter 4, we study optical states that are 100-200 meV lower in energy than the band gap. Because we work with monodisperse quantum dots, we are able to resolve this trap state separately from the band edge state and study its optical properties. We identify the trap state as dimers that form during synthesis and ligand exchange when two bare quantum dot surfaces fuse. The findings of this thesis point to the importance of minimizing the structural disorder of the coupled quantum dot solid in addition to the energetic disorder to optimize charge carrier transport.

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.