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Determination Of Dopant Ion Mobility In Transition Metal Doped Semiconductor Nanocrystals
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Book Synopsis Determination of Dopant Ion Mobility in Transition Metal Doped Semiconductor Nanocrystals by : Michael Robert Rutherford
Download or read book Determination of Dopant Ion Mobility in Transition Metal Doped Semiconductor Nanocrystals written by Michael Robert Rutherford and published by . This book was released on 2010 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Atomic-scale Modeling of Transition-metal Doping of Semiconductor Nanocrystals by : Tejinder Singh
Download or read book Atomic-scale Modeling of Transition-metal Doping of Semiconductor Nanocrystals written by Tejinder Singh and published by . This book was released on 2011 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Modulating Dopant-defect Interactions in Transition Metal Doped Colloidal Strontium Titanate Nanocrystals by : William Harrigan
Download or read book Modulating Dopant-defect Interactions in Transition Metal Doped Colloidal Strontium Titanate Nanocrystals written by William Harrigan and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Perovskites such as strontium titanate, a wide band gap semiconductor have been widely studied due to the multitude of potential applications in photocatalysis, multiferroics, sensing, and microelectronics. Various novel optical, electrical and magnetic properties can be imparted through the introduction of different transition metal dopant ions. The introduction of these impurities has been shown to impart functionality for various applications. The use of Cr3+ has been shown to introduce defect levels into the band structure of SrTiO3 and increase visible light utilization for photocatalysis. Transition metal doped highly crystalline colloidal SrTiO3 nanocrystals (NC) were synthesized using two modified hydrothermal (HT) synthesis methods and subsequently characterized. Structural characterization techniques such as powder X-ray diffraction (XRD), tunneling electron microscopy (TEM) and high-resolution tunneling electron microscopy (HR-TEM) proved vital in confirming the successful synthesis of highly crystalline sub-10 nm nanocubes. The use of transition metal doped colloidal nanocrystals will look to better understand dopant incorporation and subsequent defect formation and their interactions on the nm scale. The use of dopant specific spectroscopies such as electron paramagnetic resonance (EPR) spectroscopy was crucial in determining both the transition metal dopant oxidation state and dopant position in the colloidal NCs. Through the use of EPR spectroscopy the dopants and defects were unambiguously identified and characterized. Various surface related oxygen defects were identified and correlated to emerge under specific synthetic conditions. Site-selective internal doping of Cr or Mn was achieved through either modified HT methods. The extent of the dopant-defect interactions was studied using a photodoping technique. Under anaerobic conditions and in the presence of a hole quencher, the interactions of the photoinduced electron with SrTiO3 were monitored. The photoinduced changes were tracked using electronic absorption spectroscopy and EPR spectroscopy. An in-depth EPR analysis showed the photoinduced electron localizes on titanium atoms and undergoes cross relaxation with neighboring Cr ions.
Book Synopsis Spectroelectrochemistry by : Wolfgang Kaim
Download or read book Spectroelectrochemistry written by Wolfgang Kaim and published by Royal Society of Chemistry. This book was released on 2008 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: A practical guidebook illustrating the applications of spectroelectrochemistry to the understanding of redox reactions through identification of their intermediaries and products.
Book Synopsis Doping And Photophysical Properties Of II-VI Semiconductor Nanocrystals by :
Download or read book Doping And Photophysical Properties Of II-VI Semiconductor Nanocrystals written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Studies in Pure and Transition Metal Doped Indium Oxide Nanocrystals by : Lisa Nicole Hutfluss
Download or read book Studies in Pure and Transition Metal Doped Indium Oxide Nanocrystals written by Lisa Nicole Hutfluss and published by . This book was released on 2015 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: Controlling the crystal structure of transparent metal oxides is essential for tailoring the properties of these polymorphic materials to specific applications. Structural control is usually achieved via solid state phase transformation at high temperature or pressure. The first half of this work is a kinetic study of in situ phase transformation of In2O3 nanocrystals from metastable rhombohedral phase to stable cubic phase during their colloidal synthesis. By examining the phase content as a function of time using the model fitting approach, two distinct coexisting mechanisms are identified - surface and interface nucleation. It is shown that the mechanism of phase transformation can be controlled systematically through modulation of temperature and precursor to solvent ratio. The increase in both of these parameters leads to gradual change from surface to interface nucleation, which is associated with the increased probability of nanocrystal contact formation in the solution phase. The activation energy for surface nucleation is found to be 144±30 kJ/mol, very similar to that for interface nucleation. In spite of the comparable activation energy, interface nucleation dominates at higher temperatures due to increased nanocrystal interactions. The results of this work demonstrate enhanced control over polymorphic nanocrystal systems, and contribute to further understanding of the kinetic processes at the nanoscale, including nucleation, crystallization, and biomineralization. The ability to further modify the properties of transparent metal oxides through doping of transition metal ions into the host lattice offers a world of possibilities in terms of viable systems and applications. In particular, the use of transition metal dopants to induce room temperature ferromagnetic behaviour in non-magnetic transparent metal oxides is highly desirable for applications such as spintronics. Thus, the second half of this study is concerned with the doping of Fe into nanocrystalline In2O3 via colloidal synthesis and the fundamental characterization of the nanocrystals in anticipation of further development of these materials for potential spintronics applications. Focus is placed on the relationship between the doping concentration, observed phase of the host lattice, and nanocrystal growth and properties. Structural characterizations determine that Fe as a dopant behaves quite unlike previously studied dopants, Cr and Mn, establishing a positive correlation between increasing nanocrystal size and increasing doping concentration; the opposite was observed in the aforementioned previous systems. Through analysis of X-ray absorption near edge structure spectra and the pre-edge feature, it is found that ca. 10% of the assimilated Fe is reduced to Fe2+ during synthesis. Magnetization measurements reveal that these nanocrystals are weakly ferromagnetic at room temperature, suggesting the possibility of an interfacial defect mediated mechanism of magnetic interactions. With increasing doping concentration, the decrease in saturation magnetization suggests a change in the magnetic exchange interaction and a consequential switch from ferromagnetic to antiferromagnetic behaviour. It is clear from this work that colloidal Fe-doped In2O3 nanocrystals are a promising species, prompting further investigation using additional spectroscopic and magneto-optical techniques to increase understanding of the origin of the observed properties. A thorough understanding of this system in conjunction with other transition metal doped transparent conducting oxides will enable enhanced control in the materials design process and effectively allow tailoring of these materials for specific applications, such as spintronics.
Book Synopsis Study of Plasmonic and Magneto-optical Properties of Transition Metal Doped Indium Oxide Nanocrystals by : Yi Tan
Download or read book Study of Plasmonic and Magneto-optical Properties of Transition Metal Doped Indium Oxide Nanocrystals written by Yi Tan and published by . This book was released on 2019 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasmonic nanostructure materials have been widely investigated recently because of their considerable potential for applications in biological and chemical sensors, nano-optical devices and photothermal therapy. Compared to metal nanocrystals (NCs), doped semiconductor NCs with tunable localized surface plasmon resonance (LSPR) from near-infrared (NIR) mid-infrared (MIR) region bring more opportunities to the applications of plasmonics. Magnetoplasmonic nanostructures which could be utilized in multifunctional devices also have attracted attention due to the combination of plasmonic and magnetic properties and the manipulation of light with external magnetic fields. In this research, indium oxide (In2O3) as a typical n-type semiconductor with high mobility and carrier concentration is selected as the host lattice for doping, and molybdenum (Mo) and tungsten (W) which are transition metal elements from the same group as dopants. Colloidal molybdenum-doped indium oxide (IMO) NCs and tungsten-doped indium oxide (IWO) NCs with varying doping concentrations have been successfully synthesized, and their plasmonic and magneto-optical properties have been explored. Similarities and differences between IMO NCs and IWO NCs were discussed. Both IMO and IWO NCs have shown good tunability of plasmon resonance in the MIR range approximately from 0.22 eV to 0.34 eV. 9.2 % IMO NCs show the strongest LSPR at 0.34 eV and the maximum free electron concentration of 1.1x1020 cm-3, and 1.5 % IWO NCs exhibit the strongest LSPR at 0.33 eV with the free electron concentration of 0.94x1020 cm-3. The magneto-optical properties were studied by magnetic circular dichroism (MCD) spectroscopy. The variable-temperature-variable-field MCD spectra that coincide with the band gap absorption, indicate the excitonic splitting in the NCs. A robust MCD intensity at room temperature suggests intrinsic plasmon-exciton coupling and carrier polarization induced by plasmon, which might be phonon-mediated. A decrease in MCD signal with temperature and the saturation-like field dependence of MCD intensity for IMO and IWO NCs may related to the different oxidation states of the dopant ions since the reduced 5+ oxidation states can exhibit the Curie-type paramagnetism. IMO and IWO NCs show the coupling between exciton and plasmon in a single-phase which opens a possibility for their application in electronics and photonics. Moreover, magnetoplasmonic modes provide a new degree of freedom for controlling carrier polarization at room temperature in practical photonic, optoelectronic and quantum-information processing devices.
Book Synopsis Transition Metal Impurities in Semiconductors, by : Ėrazm Mikhaĭlovich Omelʹi︠a︡novskiĭ
Download or read book Transition Metal Impurities in Semiconductors, written by Ėrazm Mikhaĭlovich Omelʹi︠a︡novskiĭ and published by CRC Press. This book was released on 1986 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of impurities and defects in semiconductors is of fundamental interest and is important for technological applications. This monograph is a first attempt to generalise experimental data and theoretical interpretation about the nature and behaviour of impurity atoms of transition metals in semiconductors. The nature of impurities and changes in their electronic structure are analysed. The molecualr orbital approach is followed extensively in the theoretical interpretation, with particular emphasis on crystal field splitting, electron paramagnetic resonance and optical absorption spectoscopies. Coverage of experimental data is extensive with more the 300 references to the literature. This is a translation of a Russian text published in 1983. The authors have updated the content for the English language edition. This book will be of interest to scientists and engineers in solid state physics and chemistry, materials science and electronic engineering. It should also be useful for postgraduate students in these fields.
Book Synopsis Cluster Beam Deposition of Functional Nanomaterials and Devices by : Paolo Milani
Download or read book Cluster Beam Deposition of Functional Nanomaterials and Devices written by Paolo Milani and published by . This book was released on 2020-03 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cluster Beam Deposition of Functional Nanomaterials and Devices, Volume 15, provides up-to-date information on the CBD of novel nanomaterials and devices. The book offers an overview of gas phase synthesis in a range of nanoparticles, along with discussions on the development of several devices and applications. Applications include, but are not limited to catalysis, smart nanocomposites, nanoprobes, electronic devices, gas sensors and biosensors. This is an important reference source for materials scientists and engineers who want to learn more about this sustainable, innovative manufacturing technology.
Book Synopsis Emerging Trends in TiO2 Photocatalysis and Applications by : Trong-On Do
Download or read book Emerging Trends in TiO2 Photocatalysis and Applications written by Trong-On Do and published by MDPI. This book was released on 2020-12-28 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt: The semiconductor titanium dioxide (TiO2) has been evolved as a prototypical material to understand the photocatalytic process, and has been demonstrated for various photocatalytic applications such as pollutants degradation, water splitting, heavy metal reduction, CO2 conversion, N2 fixation, bacterial disinfection, etc. Rigorous photocatalytic studies on TiO2 have paved the way to understanding the various chemical processes involved and the physical parameters (optical and electrical) required to design and construct diverse photocatalytic systems. Accordingly, it has been realized that an effective photocatalyst should have ideal band edge potential, narrow band gap energy, reduced charge recombination, enhanced charge separation, improved interfacial charge transfer, surface-rich catalytic sites, etc. As a result, many strategies have been developed to design a variety of photocatalytic systems, which include doping, composite formation, sensitization, co-catalyst loading, etc. Towards highlighting the above-mentioned diversities in TiO2 photocatalysis, there have been many interesting original research works on TiO2, involving material designs for various photocatalytic applications published in this Special Issue. In addition, some excellent review papers have also been published in this Special Issue, focusing on the various TiO2-based photocatalytic systems and their mechanisms and applications.
Book Synopsis Photocatalytic Degradation of Dyes by : Sushma Dave
Download or read book Photocatalytic Degradation of Dyes written by Sushma Dave and published by Elsevier. This book was released on 2021-08-09 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photocatalytic Degradation of Dyes: Current Trends and Future Perspectives covers in detail current trends and future aspects on photocatalytic degradation of organic dyes using novel photocatalytic techniques such as metallic nanoparticles, heterogeneous and hybrid systems using visible light irradiation. It highlights the most recent scientific and technological achievements and importance of degradation of dyes in the textile effluent by simple environmental friendly approaches using eco-friendly catalysts. It is of assistance to everyone interested in bioremediation of effluents: professionals, consulting engineers, academicians, and research scholars as well. Describes the basic photocatalytic techniques and their application in wastewater treatment Covers the key reactive species accounting for the photodegradation of different dyes, providing helpful guidelines that could be applied to foster the development of efficient photodegradation systems Includes Description of a wide variety of catalysts and their application in degradation of dyes in the effluent of variable matrices (such as textile effluent, pharmaceutical industry effluent, food industry effluent) Presents the application of doped semiconductors in the degradation of dyes, hybrid systems and their importance in the dye degradation Describes the biological synthesis of metallic nanostructures and their use in dye degradation using visible range of light irradiation Discusses the mechanistic aspect of the dye degradation using photo catalysts
Book Synopsis Interfacial Engineering in Functional Materials for Dye-Sensitized Solar Cells by : Alagarsamy Pandikumar
Download or read book Interfacial Engineering in Functional Materials for Dye-Sensitized Solar Cells written by Alagarsamy Pandikumar and published by John Wiley & Sons. This book was released on 2019-12-12 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Offers an Interdisciplinary approach to the engineering of functional materials for efficient solar cell technology Written by a collection of experts in the field of solar cell technology, this book focuses on the engineering of a variety of functional materials for improving photoanode efficiency of dye-sensitized solar cells (DSSC). The first two chapters describe operation principles of DSSC, charge transfer dynamics, as well as challenges and solutions for improving DSSCs. The remaining chapters focus on interfacial engineering of functional materials at the photoanode surface to create greater output efficiency. Interfacial Engineering in Functional Materials for Dye-Sensitized Solar Cells begins by introducing readers to the history, configuration, components, and working principles of DSSC It then goes on to cover both nanoarchitectures and light scattering materials as photoanode. Function of compact (blocking) layer in the photoanode and of TiCl4 post-treatment in the photoanode are examined at next. Next two chapters look at photoanode function of doped semiconductors and binary semiconductor metal oxides. Other chapters consider nanocomposites, namely, plasmonic nanocomposites, carbon nanotube based nanocomposites, graphene based nanocomposites, and graphite carbon nitride based nanocompositesas photoanodes. The book: Provides comprehensive coverage of the fundamentals through the applications of DSSC Encompasses topics on various functional materials for DSSC technology Focuses on the novel design and application of materials in DSSC, to develop more efficient renewable energy sources Is useful for material scientists, engineers, physicists, and chemists interested in functional materials for the design of efficient solar cells Interfacial Engineering in Functional Materials for Dye-Sensitized Solar Cells will be of great benefit to graduate students, researchers and engineers, who work in the multi-disciplinary areas of material science, engineering, physics, and chemistry.
Book Synopsis Journal by : American Chemical Society
Download or read book Journal written by American Chemical Society and published by . This book was released on 2003 with total page 686 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Metal Oxide Nanostructures by : Daniela Nunes
Download or read book Metal Oxide Nanostructures written by Daniela Nunes and published by Elsevier. This book was released on 2018-11-01 with total page 331 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal Oxide Nanostructures: Synthesis, Properties and Applications covers the theoretical and experimental aspects related to design, synthesis, fabrication, processing, structural, morphological, optical and electronic properties on the topic. In addition, it reviews surface functionalization and hybrid materials, focusing on the advantages of these oxide nanostructures. The book concludes with the current and future prospective applications of these materials. Users will find a complete overview of all the important topics related to oxide nanostructures, from the physics of the materials, to its application. Delves into hybrid structured metal oxides and their promising use in the next generation of electronic devices Includes fundamental chapters on synthesis design and the properties of metal oxide nanostructures Provides an in-depth overview of novel applications, including chromogenics, electronics and energy
Book Synopsis Semiconductor Nanomaterials by : Challa S. S. R. Kumar
Download or read book Semiconductor Nanomaterials written by Challa S. S. R. Kumar and published by John Wiley & Sons. This book was released on 2010-04-05 with total page 499 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book series Nanomaterials for the Life Sciences, provides an in-depth overview of all nanomaterial types and their uses in the life sciences. Each volume is dedicated to a specific material class and covers fundamentals, synthesis and characterization strategies, structure-property relationships and biomedical applications. The series brings nanomaterials to the Life Scientists and life science to the Materials Scientists so that synergies are seen and developed to the fullest. Written by international experts of various facets of this exciting field of research, the series is aimed at scientists of the following disciplines: biology, chemistry, materials science, physics, bioengineering, and medicine, together with cell biology, biomedical engineering, pharmaceutical chemistry, and toxicology, both in academia and fundamental research as well as in pharmaceutical companies. VOLUME 6 - Semiconductor Nanomaterials
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Colloidal Semiconductor Nanocrystals: Synthesis, Properties, and Applications by : Vladimir Lesnyak
Download or read book Colloidal Semiconductor Nanocrystals: Synthesis, Properties, and Applications written by Vladimir Lesnyak and published by Frontiers Media SA. This book was released on 2020-01-06 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
