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Semiconductor Quantum Dots (semiconductor + quantum_dot)
Selected Abstracts2nd International Conference on Semiconductor Quantum Dots (QD 2002) in Tokyo, Japan, 30 September,3 October 2002PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2003R. Heitz No abstract is available for this article. [source] Proceedings of the 2nd International Conference on Semiconductor Quantum Dots (QD2002)PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003Y. Arakawa The International Conference on Semiconductor Quantum Dots (QD2002) was held at Komaba Campus of University of Tokyo, Japan, from Monday, 30 September, through Thursday, 3 October 2002. The purpose of the QD2002 was to bring together scientists from different fields of physics and chemistry to discuss topics of common interest and significance in such growing areas including semiconductor quantum dots, nanocrystals, and clusters. The conference was focused on the optical and electronic properties of three-dimensionally confined nanostructures grown both by epitaxial methods and chemical preparation routes. The QD2002 was the second in a series which started in Munich, Germany, in 2000. The scope of the QD2002 covered various research fields including novel fabrication techniques of nanoheterostructures, electronic structures, optical properties, electronic properties/single electron tunneling processes, molecular dots, nanocrystals, device applications such as lasers and memories, coherent processes/quantum computations, and biomedical applications. [source] ChemInform Abstract: Electronic Absorption Spectroscopy of Cobalt Ions in Diluted Magnetic Semiconductor Quantum Dots: Demonstration of an Isocrystalline Core/Shell Synthetic Method.CHEMINFORM, Issue 15 2002Pavle V. Radovanovic Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Quantum-Dot-Labeled DNA Probes for Fluorescence In Situ Hybridization (FISH) in the Microorganism Escherichia coliCHEMPHYSCHEM, Issue 5 2006Sheng-Mei Wu Abstract Semiconductor quantum dots (QDs) as a kind of nonisotopic biological labeling material have many unique fluorescent properties relative to conventional organic dyes and fluorescent proteins, such as composition- and size-dependent absorption and emission, a broad absorption spectrum, photostability, and single-dot sensitivity. These properties make them a promising stable and sensitive label, which can be used for long-term fluorescent tracking and subcellular location of genes and proteins. Here, a simple approach for the construction of QD-labeled DNA probes was developed by attaching thiol-ssDNA to QDs via a metal,thiol bond. The as-prepared QD-labeled DNA probes had high dispersivity, bioactivity, and specificity for hybridization. Based on such a kind of probe with a sequence complementary to multiple clone sites in plasmid pUC18, fluorescence in situ hybridization of the tiny bacterium Escherichia coli has been realized for the first time. [source] Today's challenges in quantum dot materials research for tomorrow's quantum functional devicesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 8 2007Richard Nötzel Abstract Size, shape, position control, and self-organized lateral ordering of epitaxial semiconductor quantum dot (QD) arrays are demonstrated. This constitutes the prerequisite for the ultimate control of the electronic and optical properties of man-made semiconductor heterostructures at the single and multiple charge, spin, and photon level, including their quantum mechanical and electromagnetic interactions in view of applications such as quantum information processing and computing. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical spin orientation of a single manganese atomPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2010C. Le Gall Abstract An optical spin orientation is achieved for a Mn atom localized in a semiconductor quantum dot using quasiresonant excitation at zero magnetic field. Optically created spin polarized carriers generate an energy splitting of the Mn spin and enable magnetic moment orientation controlled by the photon helicity and energy. The dynamics and the magnetic field dependence of the optical pumping mechanism shows that the spin lifetime of an isolated Mn atom at zero magnetic field is controlled by a magnetic anisotropy induced by the built-in strain in the quantum dots. Relaxation times exceeding the micro-second range are measured (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Narrowing of exciton linewidth of a quantum dot with increasing temperaturePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2009Kazuki Bando Abstract Spectral narrowing of exciton luminescence at the elevated temperature was observed in a semiconductor quantum dot (QD). The Fourier spectroscopy was used for the study of decoherence processes of excitons in the single QD. High resolution spectra of the excitons were obtained from the Fourier transform of the decay profile of the exciton decoherence. We found that the exciton linewidth in the QD at low temperature was predominated by spectral diffusion due to carriers trapped at localized sites around the QD and the narrowing of the exciton line was induced by thermally activated escape processes of the carriers from the trap sites. The narrowing of the exciton line also indicates that the exciton decoherence in the semiconductor quantum dots is predominated by environmental fluctuation rather than the exciton-phonon interaction at low temperature. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Origin of asymmetric splitting of a neutral exciton in a single semiconductor quantum dotPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2006I. Suemune Abstract It is well-recognized that exciton-state energy splitting makes it difficult to generate entangled photon pairs (EPP) from a single quantum dot (QD). It will be shown that the splitting of the exciton states originates from not only QD anisotropy but also ionization of residual impurities. This result shows that the growth of highly pure barrier layers will be necessary for the generation of EPP. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Exciton-donor complexes in a semiconductor quantum dot in a magnetic fieldPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2006A. P. Djotyan Abstract The binding energy of the ground state of a charged exciton-donor complex in a spherical semiconductor quantum dot in the presence of a homogeneous magnetic field has been calculated. The theoretical analysis is carried out using a variational approach in the framework of the adiabatic approximation. The behavior of the binding energy of the complex in a QD on magnetic field is investigated for different values of the QD radius. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Entanglement-buildup through charged-exciton decay in a semiconductor quantum dotPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2004Ulrich Hohenester Abstract We analyze the decay of a single-electron charged exciton in a quantum dot embedded in a field effect structure. We show how the quantum properties of the charged exciton are transferred through tunneling and relaxation to the spin entanglement between electrons in the dot and contact, carefully examine the proper theoretical description of the underlying scattering processes, and identify the pertinent disentanglement mechanisms. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Sense the Electrons that Come and GoCHEMPHYSCHEM, Issue 1 2004Daniël Vanmaekelbergh Prof. Dr. Electron tunneling dynamics: This highlight outlines how fluctuations in the electron number of a semiconductor quantum dot, connected to a source and drain electrode by tunneling barriers (see green circuit in the picture) and capacitively coupled to a gate electrode (black), can be measured by an independent single electron transistor (gray circuit). This allows to probe the tunneling dynamics between the quantum dot and the source and drain electrodes in the (green) quantum dot circuit with microsecond time resolution. [source] Generation of single photons and correlated photon pairs using InAs quantum dotsFORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 11-12 2004C. Santori This article reviews recent work on non-classical light generation using semiconductor quantum dots. Experimental results for single-photon generation are presented, including suppression of the two-photon probability, coherence properties and two-photon interference. An experiment demonstrating generation of polarization-correlated photon pairs from biexciton recombination is also reviewed. [source] Illuminating Dark Plasmons of Silver Nanoantenna Rings to Enhance Exciton,Plasmon InteractionsADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Hong-Mei Gong Abstract The chemical growth of silver nanorings that possess singly twinned crystals and a circular cross section via a reductive reaction solution is reported. The wire and ring diameters of the synthesized nanorings are in the ranges 80,200,nm and 4.5,18.0,,m, respectively. By lighting up the multipolar dark plasmons with slanted illumination, the silver nanoring exhibits unique focused scattering and large local-field enhancement. We also demonstrate strong exciton,plasmon interactions between a monolayer of CdSe/ZnS semiconductor quantum dots and a single silver antenna-like nanoring (nanoantenna) at the "hot spots" located at the cross points of the incident plane and nanoring; the position of these spots are tunable by adjusting the incidence angle of illumination. The tunable plasmonic behavior of the silver nanorings could find applications as optical nanoantennae or plasmonic nanocavities. [source] SERS-Coded Gold Nanorods as a Multifunctional Platform for Densely Multiplexed Near-Infrared Imaging and Photothermal HeatingADVANCED MATERIALS, Issue 31 2009Geoffrey von Maltzahn Screening nanorods coated with a mixture of SERS active molecules and biocompatible polymer identifies three formulations that may be uniquely distinguished in vivo over a spectral bandwidth of only 6,nm in the near-infrared (a spectral multiplexing density over an order of magnitude greater than attainable with semiconductor quantum dots, organic fluorochromes, and Raleigh scattering nanoparticle imaging approaches), while providing intense photothermal heating for cancer therapy. [source] Entangled photon pairs from radiative cascades in semiconductor quantum dotsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 15 2006N. Akopian Abstract Entangled photon pairs are emitted from a biexciton decay cascade of single quantum dots when spectral filtering is applied. We show this by experimentally measuring the density matrix of the polarization state of the photon pair emitted from a continuously pumped quantum dot. The matrix clearly satisfies the Peres criterion for entanglement. By applying in addition a temporal window, the quantum dot becomes an entangled light source. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Narrowing of exciton linewidth of a quantum dot with increasing temperaturePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2009Kazuki Bando Abstract Spectral narrowing of exciton luminescence at the elevated temperature was observed in a semiconductor quantum dot (QD). The Fourier spectroscopy was used for the study of decoherence processes of excitons in the single QD. High resolution spectra of the excitons were obtained from the Fourier transform of the decay profile of the exciton decoherence. We found that the exciton linewidth in the QD at low temperature was predominated by spectral diffusion due to carriers trapped at localized sites around the QD and the narrowing of the exciton line was induced by thermally activated escape processes of the carriers from the trap sites. The narrowing of the exciton line also indicates that the exciton decoherence in the semiconductor quantum dots is predominated by environmental fluctuation rather than the exciton-phonon interaction at low temperature. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Interplay of electron,phonon and Coulomb interaction in semiconductor quantum dotsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2006J. Förstner The cover picture of this issue of physica status solidi (c) has been taken from the article [1]. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Generalized pair approximation in the description of the ac conductivity of a dense disordered array of quantum dotsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2006I. P. Zvyagin Abstract The frequency dependence of the hopping conductivity of dense arrays of semiconductor quantum dots of size substantially exceeding the edge-to-edge separation between the neighboring quantum dots is considered. It is shown that at low frequencies in a wide frequency range the conductivity obeys a fractional power law and its magnitude depends on the structural characteristics of the material. The possibility of the deviations from universality related to the material structure is discussed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Proceedings of the 2nd International Conference on Semiconductor Quantum Dots (QD2002)PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003Y. Arakawa The International Conference on Semiconductor Quantum Dots (QD2002) was held at Komaba Campus of University of Tokyo, Japan, from Monday, 30 September, through Thursday, 3 October 2002. The purpose of the QD2002 was to bring together scientists from different fields of physics and chemistry to discuss topics of common interest and significance in such growing areas including semiconductor quantum dots, nanocrystals, and clusters. The conference was focused on the optical and electronic properties of three-dimensionally confined nanostructures grown both by epitaxial methods and chemical preparation routes. The QD2002 was the second in a series which started in Munich, Germany, in 2000. The scope of the QD2002 covered various research fields including novel fabrication techniques of nanoheterostructures, electronic structures, optical properties, electronic properties/single electron tunneling processes, molecular dots, nanocrystals, device applications such as lasers and memories, coherent processes/quantum computations, and biomedical applications. [source] Optical spectra of quantum dots: effects of non-adiabaticityPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003J. T. Devreese Abstract It is shown that in many cases an adequate description of optical spectra of semiconductor quantum dots requires a treatment beyond the commonly used adiabatic approximation. We have developed a theory of phonon-assisted optical transitions in semiconductor quantum dots, which takes into account non-adiabaticity of the exciton,phonon system. Effects of non-adiabaticity lead to a mixing of different exciton and phonon states that provides a key to the understanding of surprisingly high intensities of phonon satellites observed in photoluminescence spectra of quantum dots. A breakdown of the adiabatic approximation gives an explanation also for discrepancies between the serial law, observed in multi-phonon optical spectra of some quantum dots, and the Franck,Condon progression, prescribed by the adiabatic approach. [source] Cysteine-capped ZnSe quantum dots as affinity and accelerating probes for microwave enzymatic digestion of proteins via direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 15 2009Lokesh A. Shastri Fluorescent semiconductor quantum dots (QDs) exhibit great potential and capability for many biological and biochemical applications. We report a simple strategy for the synthesis of aqueous stable ZnSe QDs by using cysteine as the capping agent (ZnSe-Cys QDs). The ZnSe QDs can act as affinity probes to enrich peptides and proteins via direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis. This nanoprobe could significantly enhance protein signals (insulin, ubiquitin, cytochrome c, myoglobin and lysozyme) in MALDI-TOFMS by 2.5,12 times compared with the traditional method. Additionally, the ZnSe-Cys QDs can be applied as heat absorbers (as accelerating probes) to speed up microwave-assisted enzymatic digestion reactions and also as affinity probes to enrich lysozyme-digested products in MALDI-TOFMS. Furthermore, after the enrichment experiments, the solutions of ZnSe-Cys QDs mixed with proteins can be directly deposited onto the MALDI plates for rapid analysis. This approach shows a simple, rapid, efficient and straightforward method for direct analysis of proteins or peptides by MALDI-TOFMS without the requirement for further time-consuming separation processes, tedious washing steps or laborious purification procedures. The present study has demonstrated that ZnSe-Cys QDs are reliable and potential materials for rapid, selective separation and enrichment of proteins as well as accelerating probes for microwave-digested reactions for proteins than the regular MALDI-MS tools. Additionally, we also believe that this work may also inspire investigations for applications of QDs in the field of MALDI-MS for proteomics. Copyright © 2009 John Wiley & Sons, Ltd. [source] Quantum Dots Arrangement and Energy Transfer Control via Charge-Transfer Complex Achieved on Poly(Phenylene Ethynylene)/Schizophyllan NanowiresCHEMISTRY - AN ASIAN JOURNAL, Issue 9 2009Tomohiro Shiraki Abstract Assemblies of organic and inorganic compounds in the nanoscale region have contributed to the development of novel functional materials toward future applications, including sensors and opto-electronics. We succeed in fabricating hybrid nanowires composed of a conjugated polymer and semiconductor quantum dots (QDs) by a supramolecular assembly technique. The 1-D fashion of the nanowire structure is obtained by the polymer wrapping of cationic poly(phenylene ethynylene) (PPE) with helix-forming polysaccharide schizophyllan (SPG). The electrostatic interaction between cationic PPE and anionic QDs affords the nanowires decorated with QDs. Upon addition of an acceptor molecule, tetranitrofluorenone (TNF), the charge-transfer (CT) complex between PPE and TNF is formed, resulting in energy transfer from the QDs to PPE arising from the induced spectral overlap. Furthermore, the employment of the conjugated polymer allows highly sensitive quenching of the QD's emission by raising the transmission efficiency to the CT complexed electron deficient sites along the polymer backbone. [source] | ||||||||||||||||