Quantum Dots And Nanowires
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Quantum Dots And Nanowires
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Author : Supriyo Bandyopadhyay
language : en
Publisher:
Release Date : 2003
Quantum Dots And Nanowires written by Supriyo Bandyopadhyay and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Science categories.
Quantum Dots and Nanowires provides coverage on various emerging aspects of quantum dots and nanowires. This book covers recent advances in physical and chemical synthetic approaches, processing and fabrication of semiconductor quantum-dot arrays, superlattices, self-assemblies, nanowires, nanotubes and nanobelts, computational modeling approaches, spectroscopic characterization, their unique electrical, optical, magnetic and physical properties associated with size effect, transport phenomena, quantum computing, and other potential applications.
Quantum Dots Nanoparticles And Nanowires Volume 789
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Author : P. Guyot-Sionnest
language : en
Publisher:
Release Date : 2004-05-04
Quantum Dots Nanoparticles And Nanowires Volume 789 written by P. Guyot-Sionnest and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004-05-04 with Science categories.
Nanostructures of semiconductors and metals show novel optical and transport properties, and offer the perspective of designing materials properties with unprecedented flexibility and control. This has motivated research in the synthesis and characterization of new materials. This 2004 book brings together scientists with various levels of expertise in the growth, characterization and applications of inorganic nanostructures, such as quantum dots, nanowires and nanorods, to discuss and share developments in the field. Reports focus on techniques to prepare and characterize novel materials, investigations of novel optical and electronic properties, and novel applications, such as those that are biologically inspired. Topics include: synthesis and characterization of semiconductor quantum dots, nanoparticles and nanowires using wet chemistry and molecular beam approaches; synthesis, characterization and novel properties of metallic nanostructures; optical properties of neutral and charged excitons and exciton complexes in self-assembled quantum dots; nanoscale devices and sensors based on nanostructures and their properties; and design and characterization of quantum dot-bioconjugates and their use in assay developments.
Molecular Nanowires And Other Quantum Objects
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Author : Alexandre S. Alexandrov
language : en
Publisher: Springer Science & Business Media
Release Date : 2004-04-30
Molecular Nanowires And Other Quantum Objects written by Alexandre S. Alexandrov and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004-04-30 with Technology & Engineering categories.
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.
Characterizing Single Photon Emission From Quantum Dots In Nanowires
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Author : Morgan Mastrovich
language : en
Publisher:
Release Date : 2019
Characterizing Single Photon Emission From Quantum Dots In Nanowires written by Morgan Mastrovich and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Nanowires categories.
Bright sources of highly indistinguishable single photons are desirable for diverse applications in quantum technology, including quantum cryptographic protocols, information processing, and metrology. The most common single photon source for quantum optical experiments is currently spontaneous parametric downconversion (SPDC); quantum dot sources have the potential to greatly exceed the brightness of these current sources, without compromising the quality of the emitted photons. Embedding a quantum dot within a tapered nanowire waveguide greatly increases the photon extraction efficiency. Exciting a two-photon resonant transition decreases the emission time jitter, improving both the multi-photon suppression and indistinguishability. Before this work, these two techniques have not yet been implemented together. We implemented two-photon resonant excitation (TPRE) for the first time in nanowire-embedded quantum dots; we found that it significantly improved the multi-photon suppression. However, we were unable to measure the indistinguishability due to low counts and instabilities in the experimental apparatus. Nevertheless, we have identified the significant improvements that are still required in order to successfully measure the indistinguishability under TPRE; with these improvements, the measurement should be possible for future group members. We successfully measured the indistinguishability under a quasi-resonant excitation, but did not find a significant difference when comparing to the measurement made on a similar quantum dot under above-bandgap excitation. We must also substantially improve the single photon count rate in order to approach the polarization entanglement rates of SPDC sources. Despite these challenges, nanowire-embedded quantum dots remain a promising source of both single and entangled pairs of photons.
Handbook Of Nanophysics
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Author : Klaus D. Sattler
language : en
Publisher: CRC Press
Release Date : 2010-09-17
Handbook Of Nanophysics written by Klaus D. Sattler and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-09-17 with Science categories.
Intensive research on fullerenes, nanoparticles, and quantum dots in the 1990s led to interest in nanotubes and nanowires in subsequent years. Handbook of Nanophysics: Nanotubes and Nanowires focuses on the fundamental physics and latest applications of these important nanoscale materials and structures. Each peer-reviewed chapter contains a broad-
Optics Of Quantum Dots And Wires
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Author : Garnett W. Bryant
language : en
Publisher: Artech House Publishers
Release Date : 2005
Optics Of Quantum Dots And Wires written by Garnett W. Bryant and has been published by Artech House Publishers this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Technology & Engineering categories.
Quantum technology is the key to next-generation optoelectronics and laser semiconductors, and this new cutting-edge book is an in-depth examination of how quantum dots and wires are fabricated and applied to optics. You find a solid tutorial on the optical properties of nanoscale dots and wires that explains the current state of this technology and why it is so promising. The book presents a detailed survey of techniques based on molecular beam epitaxial growth for fabricating semiconductor quantum dots and wires. You learn how to assess these growth strategies for insertion of dots and wires into devices.
Magnetooptical Properties Of Dilute Nitride Nanowires
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Author : Mattias Jansson
language : en
Publisher: Linköping University Electronic Press
Release Date : 2020-06-18
Magnetooptical Properties Of Dilute Nitride Nanowires written by Mattias Jansson and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-06-18 with Electronic books categories.
Nanostructured III-V semiconductors have emerged as one of the most promising materials systems for future optoelectronic applications. While planar III-V compounds are already at the center of the ongoing lighting revolution, where older light sources are replaced by modern white light LEDs, fabricating such materials in novel architectures, such as nanowires and quantum dots, creates new possibilities for optoelectronic applications. Not only do nanoscale structures allow the optically active III-V materials to be integrated with silicon microelectronics, but they also give rise to new fascinating properties inherent to the nanoscale. One of the key parameters considered when selecting materials for applications in light-emitting and photovoltaic devices is the band gap energy. While alloying of conventional III-V materials provides a certain degree of band gap tunability, a significantly enhanced possibility of band gap engineering is offered by so-called dilute nitrides, where incorporation of a small percentage of nitrogen into III-V compounds causes a dramatic down-shift of the conduction band edge. In addition, nitrogen-induced splitting of the conduction band in dilute nitrides can be utilized in intermediate band solar cells, belonging to the next generation of photovoltaic devices. For any material to be viable for optoelectronic applications, detailed knowledge of the electronic structure of the material, as well as a good understanding of carrier recombination processes is vital. For example, alloying may not only cause changes in the electronic structure but can also induce disorder. Disorder-induced potential fluctuations may alter charge carrier and exciton dynamics, and may even induce quantum confinement. Moreover, various defects in the material may introduce detrimental non-radiative (NR) states in the band gap deteriorating radiative efficiency. It is evident that, due to their different growth mechanisms, such properties could be markedly different in nanowires as compared to their planar counterparts. In this thesis, I aim to describe the electronic structure of dilute nitride nanowires, and its effects on the optical properties. Firstly, we investigate the electronic structure, and the structural and optical properties of novel GaNAsP nanowires, with a particular focus on the dominant recombination channels in the material. Secondly, we show how short-range fluctuations in the nitrogen content lead to the formation of quantum dots in dilute nitride nanowires, and investigate their electronic structure. Finally, we investigate the combined charge carrier and exciton dynamics of the quantum dots and effects of defects in their surroundings. Before considering individual sources of NR recombination, it is instructive to investigate the overall effects of nitrogen incorporation on the structural properties of the nanowires. In Paper I, we show that nitrogen incorporation up to 0.16% in Ga(N)AsP nanowires does not affect the overall structural quality of the material, nor does nitrogen degrade the good compositional uniformity of the nanowires. It is evident from our studies, however, that nitrogen incorporation has a strong and complex effect on recombination processes. We first show that nitrogen incorporation in GaNAsP nanowires reduces the NR recombination at room temperature as compared to the nitrogen-free nanowires (Paper I). This is in stark contrast to dilute nitride epilayers, where nitrogen incorporation enhances NR recombination. The reason for this difference is that in nanowires the surface recombination, rather than recombination via point defects, is the dominant NR recombination mechanism. We suggest that the nitrogen-induced suppression of the NR surface recombination in the nanowires is due to nitridation of the nanowire surface. Another NR recombination channel common in III-V nanowires is caused by the presence of structural defects, such as rotational twin planes and stacking faults. Interestingly, while nitrogen incorporation does not appear to affect the density of such structural defects, increasing nitrogen incorporation reduces the NR recombination via the structural defects (Paper II). This is explained by competing trapping of excited carriers/excitons to the localized states characteristic to dilute nitrides, and at nitrogen-induced NR defects. This effect is, however, only present at cryogenic temperatures, while at room temperature the NR recombination via the structural defects is not the dominant recombination channel. Importance of point defects in carrier recombination is highlighted in Paper III. Using the optically detected magnetic resonance technique, we show that gallium vacancies (VGa) that are formed within the nanowire volume act as efficient NR recombination centers, degrading optical efficiency of the Ga(N)AsP-based nanowires. Interestingly, while the defect formation is promoted by nitrogen incorporation, it is also readily present in ternary GaAsP nanowires. This contrasts with previous studies on planar structures, where VGa was not formed in the absence of nitrogen, unless subjected to irradiation by high-energy particles or heavy n-type doping. This, again, highlights how the defect formation is strikingly different in nanowires as compared to planar structures, likely due to the different growth processes. Potential fluctuations in the conduction band, caused by non-uniformity of the nitrogen incorporation, is characteristic to dilute nitrides and is known to cause exciton/carrier localization. We find that in dilute nitride nanowires, such fluctuations at the short range cause three-dimensional quantum confinement of excitons, resulting in optically active quantum dots with spectrally ultranarrow and highly polarized emission lines (Paper IV). A careful investigation of such quantum dots reveals that their properties are strongly dependent on the host material (Papers V, VI). While the principal quantization axis of the quantum dots formed in the ternary GaNAs nanowires is preferably oriented along the nanowire axis (Paper V), it switches to the direction perpendicular to the nanowire axis in the quaternary GaNAsP nanowires (Paper VI). Another aspect illustrating the influence of the host material on the quantum-dot properties is the electronic character of the captured hole. In both alloys, we show coexistence of quantum dots where the captured holes are of either a pure heavy-hole character or a mixed light-hole and heavy-hole character. In the GaNAs quantum dots, the main cause of the light- and heavy-hole splitting is uniaxial tensile strain induced by a combination of lattice mismatch with the nanowire core and local alloy fluctuations (Paper V). In the GaNAsP quantum dots, however, we suggest that the main mechanism for the light- and heavy-hole splitting is local fluctuations in the P/As ratio (Paper VI). Using time correlation single-photon counting, we show that the quantum dots in these dilute nitride nanowires behave as single photon emitters (Paper VI), confirming the three-dimensional quantum confinement of the emitters. Finally, since the quantum dots are formed by fluctuations mainly in the conduction band, only electrons are preferentially captured in the 0D confinement potential, whereas holes are expected to be mainly localized through the Coulomb interaction once an electron is captured by the quantum dot. In Paper VII, we investigate this rather peculiar capture mechanism, which we show to lead to unipolar, negative charging of the quantum dot. Moreover, we demonstrate that carrier capture by some quantum dots is strongly affected by the presence of defects in their local surroundings, which further alters the charge state of the quantum dot, where formation of the negatively charged exciton is promoted at the expense of its neutral counterpart. This underlines that the local surroundings of the quantum dots may greatly affect their properties and illustrates a possible way to exploit the defects for charge engineering of the quantum dots. In summary, in this thesis work, we identify several important non-radiative recombination processes in dilute nitride nanowires that can undermine the potential of these novel nanostructures for future optoelectronic applications. The gained knowledge could be found useful for designing strategies to mitigate these harmful processes, thereby improving the efficiency of future light-emitting and photovoltaic devices based on these nanowires. Furthermore, we uncover a set of optically bright quantum dot single-photon emitters embedded in the dilute nitride nanowires, and reveal their unusual electronic structure with strikingly different confinement potentials between electrons and holes. Our findings open a new pathway for charge engineering of the quantum dots in nanowires, attractive for applications in e.g. quantum computation and optical switching.
Silicon Nanomaterials Sourcebook
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Author : Klaus D. Sattler
language : en
Publisher: CRC Press
Release Date : 2017-07-28
Silicon Nanomaterials Sourcebook written by Klaus D. Sattler and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-07-28 with Science categories.
This comprehensive tutorial guide to silicon nanomaterials spans from fundamental properties, growth mechanisms, and processing of nanosilicon to electronic device, energy conversion and storage, biomedical, and environmental applications. It also presents core knowledge with basic mathematical equations, tables, and graphs in order to provide the reader with the tools necessary to understand the latest technology developments. From low-dimensional structures, quantum dots, and nanowires to hybrid materials, arrays, networks, and biomedical applications, this Sourcebook is a complete resource for anyone working with this materials: Covers fundamental concepts, properties, methods, and practical applications. Focuses on one important type of silicon nanomaterial in every chapter. Discusses formation, properties, and applications for each material. Written in a tutorial style with basic equations and fundamentals included in an extended introduction. Highlights materials that show exceptional properties as well as strong prospects for future applications. Klaus D. Sattler is professor physics at the University of Hawaii, Honolulu, having earned his PhD at the Swiss Federal Institute of Technology (ETH) in Zurich. He was honored with the Walter Schottky Prize from the German Physical Society, and is the editor of the sister work also published by Taylor & Francis, Carbon Nanomaterials Sourcebook, as well as the acclaimed multi-volume Handbook of Nanophysics.
Transport Studies Of Local Gate Defined Quantum Dots In Nanowires
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Author : Carina Fasth
language : en
Publisher:
Release Date : 2007
Transport Studies Of Local Gate Defined Quantum Dots In Nanowires written by Carina Fasth and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
Progress In Nanoscale And Low Dimensional Materials And Devices
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Author : Hilmi Ünlü
language : en
Publisher: Springer Nature
Release Date : 2022-10-18
Progress In Nanoscale And Low Dimensional Materials And Devices written by Hilmi Ünlü and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-10-18 with Technology & Engineering categories.
This book describes most recent progress in the properties, synthesis, characterization, modelling, and applications of nanomaterials and nanodevices. It begins with the review of the modelling of the structural, electronic and optical properties of low dimensional and nanoscale semiconductors, methodology of synthesis, and characterization of quantum dots and nanowires, with special attention towards Dirac materials, whose electrical conduction and sensing properties far exceed those of silicon-based materials, making them strong competitors. The contributed reviews presented in this book touch on broader issues associated with the environment, as well as energy production and storage, while highlighting important achievements in materials pertinent to the fields of biology and medicine, exhibiting an outstanding confluence of basic physical science with vital human endeavor. The subjects treated in this book are attractive to the broader readership of graduate and advanced undergraduate students in physics, chemistry, biology, and medicine, as well as in electrical, chemical, biological, and mechanical engineering. Seasoned researchers and experts from the semiconductor/device industry also greatly benefit from the book’s treatment of cutting-edge application studies.