Doping Semiconductor Nanocrystals

Doping Semiconductor Nanocrystals PDF Author: Lijun Zu
Publisher:
ISBN:
Category :
Languages : en
Pages : 352

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Book Description

Doping Semiconductor Nanocrystals

Doping Semiconductor Nanocrystals PDF Author: Lijun Zu
Publisher:
ISBN:
Category :
Languages : en
Pages : 352

Get Book Here

Book Description


Atomic-scale Modeling of Transition-metal Doping of Semiconductor Nanocrystals

Atomic-scale Modeling of Transition-metal Doping of Semiconductor Nanocrystals PDF Author: Tejinder Singh
Publisher:
ISBN:
Category : Doped semiconductors
Languages : en
Pages : 225

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Book Description
Doping in bulk semiconductors (e.g., n- or p- type doping in silicon) allows for precise control of their properties and forms the basis for the development of electronic and photovoltaic devices. Recently, there have been reports on the successful synthesis of doped semiconductor nanocrystals (or quantum dots) for potential applications in solar cells and spintronics. For example, nanocrystals of ZnSe (with zinc-blende lattice structure) and CdSe and ZnO (with wurtzite lattice structure) have been doped successfully with transition-metal (TM) elements (Mn, Co, or Ni). Despite the recent progress, however, the underlying mechanisms of doping in colloidal nanocrystals are not well understood. This thesis reports a comprehensive theoretical analysis toward a fundamental kinetic and thermodynamic understanding of doping in ZnO, CdSe, and ZnSe quantum dots based on first-principles density-functional theory (DFT) calculations. The theoretical predictions of this thesis are consistent with experimental measurements and provide fundamental interpretations for the experimental observations. The mechanisms of doping of colloidal ZnO nanocrystals with the TM elements Mn, Co, and Ni is investigated. The dopant atoms are found to have high binding energies for adsorption onto the Zn-vacancy site of the (0001) basal surface and the O-vacancy site of the (0001) basal surface of ZnO nanocrystals; therefore, these surface vacancies provide viable sites for substitutional doping, which is consistent with experimental measurements. However, the doping efficiencies are affected by the strong tendencies of the TM dopants to segregate at the nanocrystal surface facets, as indicated by the corresponding computed dopant surface segregation energy profiles. Furthermore, using the Mn doping of CdSe as a case study, the effect of nanocrystal size on doping efficiency is explored. It is shown that Mn adsorption onto small clusters of CdSe is characterized by high binding energies, which, in conjunction with the Mn surface segregation characteristics on CdSe nanocrystals, explains experimental reports of high doping efficiency for small-size CdSe clusters. In addition, this thesis presents a systematic analysis of TM doping in ZnSe nanocrystals. The analysis focuses on the adsorption and surface segregation of Mn dopants on ZnSe nanocrystal surface facets, as well as dopant-induced nanocrystal morphological transitions, and leads to a fundamental understanding of the underlying mechanisms of dopant incorporation into growing nanocrystals. Both surface kinetics (dopant adsorption onto the nanocrystal surface facets) and thermodynamics (dopant surface segregation) are found to have a significant effect on the doping efficiencies in ZnSe nanocrystals. The analysis also elucidates the important role in determining the doping efficiency of ZnSe nanocrystals played by the chemical potentials of the growth precursor species, which determine the surface structure and morphology of the nanocrystals.

Nanocrystal Quantum Dots

Nanocrystal Quantum Dots PDF Author: Victor I. Klimov
Publisher: CRC Press
ISBN: 1351834525
Category : Technology & Engineering
Languages : en
Pages : 584

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Book Description
A review of recent advancements in colloidal nanocrystals and quantum-confined nanostructures, Nanocrystal Quantum Dots is the second edition of Semiconductor and Metal Nanocrystals: Synthesis and Electronic and Optical Properties, originally published in 2003. This new title reflects the book’s altered focus on semiconductor nanocrystals. Gathering contributions from leading researchers, this book contains new chapters on carrier multiplication (generation of multiexcitons by single photons), doping of semiconductor nanocrystals, and applications of nanocrystals in biology. Other updates include: New insights regarding the underlying mechanisms supporting colloidal nanocrystal growth A revised general overview of multiexciton phenomena, including spectral and dynamical signatures of multiexcitons in transient absorption and photoluminescence Analysis of nanocrystal-specific features of multiexciton recombination A review of the status of new field of carrier multiplication Expanded coverage of theory, covering the regime of high-charge densities New results on quantum dots of lead chalcogenides, with a focus studies of carrier multiplication and the latest results regarding Schottky junction solar cells Presents useful examples to illustrate applications of nanocrystals in biological labeling, imaging, and diagnostics The book also includes a review of recent progress made in biological applications of colloidal nanocrystals, as well as a comparative analysis of the advantages and limitations of techniques for preparing biocompatible quantum dots. The authors summarize the latest developments in the synthesis and understanding of magnetically doped semiconductor nanocrystals, and they present a detailed discussion of issues related to the synthesis, magneto-optics, and photoluminescence of doped colloidal nanocrystals as well. A valuable addition to the pantheon of literature in the field of nanoscience, this book presents pioneering research from experts whose work has led to the numerous advances of the past several years.

Materials at the Nanoscale

Materials at the Nanoscale PDF Author: Awadesh Mallik
Publisher: BoD – Books on Demand
ISBN: 183968822X
Category : Technology & Engineering
Languages : en
Pages : 186

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Book Description
Nanocrystals play very important roles in the interdisciplinary fields of biology, physics and chemistry. They are used for various applications, including to develop and formulate new drugs and vaccines to fight diseases and pandemics. This book contains nine chapters that discuss nanocrystals in electronics, medicine, the food industry, geology, and more.

Doping And Photophysical Properties Of II-VI Semiconductor Nanocrystals

Doping And Photophysical Properties Of II-VI Semiconductor Nanocrystals PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Semiconductor nanocrystals with sizes comparable to the corresponding bulk excitonic diameter exhibit unique size-dependent electronic and optical properties resulting from quantum confinement effect. Such nanocrystals not only allow the study of evolution of bulk properties from the molecular limit providing important fundamental understandings, but also have great technological implications, leading to intense research over the past several years. Besides tuning the crystal size in the nm regime to obtain novel properties, an additional route to derive new functionalities has been to dope transition metal ions into a semiconductor host. Thus, transition metal doped nanocrystals are of great interest since it allows two independent ways to functionalize semiconductor materials, one via the tunability of properties by size variation and other due to properties of such dopants. Chapter 1 of the thesis provide a general introduction to the subject matters dealt in with this thesis, while the necessary methodologies have been discussed in chapter 2. Chapters 3 and 4 of this thesis deal with nanocrystal doping. Following suggestions in previous literatures that the doping of nanocrystal depends strongly upon the crystal structure of the synthesized host nanocrystal, we have studied the phase-transformation between the somewhat zinc-blende and the usual wurtzite structures for CdS and CdSe nanocrystals in chapter 5. In chapter 6 we have pointed out that a gradient structure is essential to achieve nearly ideal photoluminescence efficiency using heterostructured nanocrystals and also achieved strong two-photon absorptions, adding optical bifunctionality to these nanocrystals. Finally, in chapter 7, we establish different approaches to generate white-light using nanocrystals and their unique advantages, as a first step to realizing white light emitting devices. Chapter 1 provides a brief introduction to various interesting properties and concepts relevant for the studies c.

Microwave Heating

Microwave Heating PDF Author: Gennadiy I. Churyumov
Publisher: BoD – Books on Demand
ISBN: 1839682264
Category : Science
Languages : en
Pages : 204

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Book Description
More than 80 years of experience in the practical application of electromagnetic energy in various fields of human activity (industry, agriculture, science, medicine, etc.) suggests that microwave heating is an effective application of electromagnetic energy. This book presents the latest investigations on the applications of microwave energy and the effects of microwave radiation on various materials and mediums. Divided into two sections on thermal and nonthermal effects, this volume contains eight chapters that examine the use of microwave energy to extract bioactive compounds from plant materials, for rock-breaking operations, to synthesize functional dyes and nanomaterials, and more.

Nanocrystals

Nanocrystals PDF Author: Sudheer Neralla
Publisher: BoD – Books on Demand
ISBN: 9535107143
Category : Science
Languages : en
Pages : 214

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Book Description
Nanocrystals research has been an area of significant interest lately, due to the wide variety of potential applications in semiconductor, optical and biomedical fields. This book consists of a collection of research work on nanocrystals processing and characterization of their structural, optical, electronic, magnetic and mechanical properties. Various methods for nanocrystals synthesis are discussed in the book. Size-dependent properties such as quantum confinement, superparamagnetism have been observed in semiconductor and magnetic nanoparticles. Nanocrystals incorporated into different material systems have proven to possess improved properties. A review of the exciting outcomes nanoparticles study has provided indicates further accomplishments in the near future.

Semiconductor Nanocrystals

Semiconductor Nanocrystals PDF Author: Alexander L. Efros
Publisher: Springer Science & Business Media
ISBN: 1475736770
Category : Technology & Engineering
Languages : en
Pages : 277

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Book Description
A physics book that covers the optical properties of quantum-confined semiconductor nanostructures from both the theoretical and experimental points of view together with technological applications. Topics to be reviewed include quantum confinement effects in semiconductors, optical adsorption and emission properties of group IV, III-V, II-VI semiconductors, deep-etched and self assembled quantum dots, nanoclusters, and laser applications in optoelectronics.

Colloidal Semiconductor Nanocrystals: Synthesis, Properties, and Applications

Colloidal Semiconductor Nanocrystals: Synthesis, Properties, and Applications PDF Author: Vladimir Lesnyak
Publisher: Frontiers Media SA
ISBN: 2889632695
Category :
Languages : en
Pages : 110

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Book Description


Silicon Nanocrystals

Silicon Nanocrystals PDF Author: Lorenzo Pavesi
Publisher: John Wiley & Sons
ISBN: 9783527629961
Category : Technology & Engineering
Languages : en
Pages : 648

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Book Description
This unique collection of knowledge represents a comprehensive treatment of the fundamental and practical consequences of size reduction in silicon crystals. This clearly structured reference introduces readers to the optical, electrical and thermal properties of silicon nanocrystals that arise from their greatly reduced dimensions. It covers their synthesis and characterization from both chemical and physical viewpoints, including ion implantation, colloidal synthesis and vapor deposition methods. A major part of the text is devoted to applications in microelectronics as well as photonics and nanobiotechnology, making this of great interest to the high-tech industry.