Download or read book Synthesis of Tin and Germanium Based Semiconductor Nanocrystals written by Ying Xu and published by . This book was released on 2010 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of Tin and Germanium Based Semiconductor Nanocrystals written by Ying Xu and published by . This book was released on 2010 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of Germanium based Nanocrystals written by Hyun Gyung Kim and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Approaches to colloidal synthesis have rapidly developed to control the size, shape, and composition of various semiconductors, offering cost reductions, controllability, and scalability. Of semiconductor materials, germanium nanomaterials are known to be the most difficult to synthesize in solution-based methods because of their high crystallization temperature. Zero-dimensional germanium nanocrystals were synthesized by the heat-up method, without any strong reducing agent. Subsequently, finely controlled size-selective precipitation narrowed size distributions, and size-selected nanocrystals successfully created a monolayer germanium nanocrystals superlattice. One-dimensional germanium nanorods were synthesized by the solution–liquid–solid method using tin nanoparticles as seeds. By forming a liquid alloy with the tin seed at the eutectic temperature, which is much lower than the crystallization temperature, germanium nanorods were grown from the tin seed. A monophenylsilane enhanced the yield of germanium nanorods by promoting the phenyl redistribution of diphenylgermane, a germanium precursor. Using a mixture of HCl and HF, tin seeds were completely removed from the tips of the germanium nanorods, leaving germanium crystalline nanorods. Nonvolatile memories, a key component in various electronics and portable systems, include phase-change memory, a leading technology that has seen exponential growth in demand over the last decade. One important class of phase change materials are compounds on the GeTe–Sb2Te3 tie line. Despite interesting properties of the nanomaterials, colloidal synthesis of phase change material nanocrystals has only been rarely reported. In the present study, three representative phase change material nanocrystals, GeTe, Sb2Te3, and Ge2Sb2Te5, were successfully synthesized using the hot-injection method. A poly(vinylpyrrolidinone)–hexadecane (PVP–HDE) polymer was essential for the nanocrystal dispersion and making ternary Ge2Sb2Te5 nanocrystals. Two solvents, oleylamine and trioctylphosphine, were studied for synthesizing all three nanocrystals and reveal the conversion chemistry of phase change material precursors

Download or read book Microwave assisted Synthesis and Ligand Exchange of Germanium and Germanium tin Alloy Nanoparticles written by Kathryn Ann Newton and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Germanium is an indirect band gap semiconductor in Group IV. Ge has a bulk band gap of 0.67 eV and a Bohr radius of 24 nm. Because of its large Bohr radius, Ge nanoparticles (Ge NPs) are quantum confined over a wide size range, and its band gap can be tuned as a function of particle size, composition, or surface passivation. Ge NPs have been achieved by colloidal synthesis routes using convection and microwave-assisted heating methods. The presented work applies microwave-assisted heating to the synthesis and ligand exchange of colloidal Ge NPs and germanium-tin alloy nanoparticles (Ge[subscript 1-x]Sn[subscript x] NPs). Chapter 1 is a brief introduction to Group IV semiconductor nanoparticles. It reviews research in the colloidal synthesis and ligand exchange of Ge and Ge[subscript 1-x]Sn[subscript x] NPs. Chapter 2 demonstrates the synthesis of Ge NPs by the reduction of GeI2 and GeI4 in oleylamine using microwave-assisted heating. The effects of precursor ratio, temperature, and solvent are considered. An optimized ligand exchange procedure, using N2H4 to remove the oleylamine ligand from the surface of Ge NPs, is also presented. In Chapter 3, microwave-assisted methods are applied to the synthesis and ligand exchange of Ge[subscript 1-x]Sn[subscript x] NPs, which are prepared by the reduction of GeI2 and bis[bis(trimethylsilyl)amino]tin(II). It is demonstrated that reaction temperature can be used to control particle size over a narrow Sn composition range. Surface passivation with dodecanethiol is achieved by ligand exchange without loss of Sn composition. Tauc plot analysis of optical absorbance spectra confirm an indirect band gap for Ge[subscript 1-x]Sn[subscript x] NPs. Microwave-assisted heating methods are applied to the reduction of GeI2 in the presence of SiI4 in oleylamine in Chapter 4. The synthesized Ge NPs are observed to increase in size and crystallinity, relative to Ge NPs synthesized without SiI4 in the reaction, as the amount of SiI4 in the reaction is increased. SEM-EDS and STEM-EELS confirm Si is in the nanoparticle ensemble and is localized around the outside of the Ge NPs. Quantum confinement is confirmed by optical spectroscopy, and cyclic voltammetry shows changes in band gap originate from changes in conduction band energy. Additional investigation of the effects of nanoparticle synthesis temperature, solvent, and ligand concentration on ligand exchange are also presented. In Chapter 5, ligand exchange using dioctadecyl disulfide as a ligand precursor is demonstrated in the re-passivation of oleylamine-capped Ge NPs with octadecanethiol. Oleylamine is removed from the surface of Ge NPs by sonication with N2H4. Re-passivation is achieved by stirring solutions of uncapped-Ge NPs, dioctyldecyl disulfide, and diphenylphosphine. Microwave-assisted heating of this solution at 150 °C also achieves re-passivation. Direct ligand exchange methods, in which oleylamine-capped Ge NPs are stirred with dioctadecyl disulfide and diphenylphosphine, are also demonstrated to achieve octadecanethiol passivation. Appendix 1 provides details of additional investigation in the colloidal synthesis of Ge[subscript 1-x]Sn[subscript x] NPs. The reduction of GeI2 and bis[bis(trimethylsilyl)amino]tin(II) in hexadecylamine using microwave-assisted heating is demonstrated to yield alloy NPs with Sn impurities. It is shown that reaction temperature can be used to control Sn composition over a narrow particle size range when GeI2 and bis[bis(trimethylsilyl)amino]tin(II) are reduced in octylamine. The effects of reaction volume were also investigated. The effects of size and morphology of nano tungsten(VI) oxide (WO3) on photocatalytic water oxidation are presented in Appendix 2. Nanodots (32 ± 16 nm), nanoplates (476 ± 98 nm by 58 ± 16 nm), and WO3 microcrystals (~2 [mu]m) were applied as anode materials for the photocatalytic oxidation of water, generating 31.6, 16.5, and 2.9 [mu]mol h-1 O2 (g), respectively. Photoelectrochemistry experiments demonstrate that anodic photocurrent decreases with particle size but little change in photo-onset potential is observed. The one-dimensional continuity model is used to describe trends in photocatalytic activity, which are attributed to minority and majority carrier transport kinetics.

Download or read book Colloidal Synthesis and Characterization of Pristine and Compositionally Manipulated Germanium Nanocrystals written by Katayoon Tabatabaei and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A tremendous amount of research efforts were focused on conventional compound semiconductor nanomaterials. Group IV (Si and Ge) semiconducting materials in nanoscale are of significant research interest due to their unique and promising properties in a broad range of technological applications. While during the last two decades, Ge NCs as non-toxic alternatives over metal chalcogenides or group III-V quantum dots were studied by different research group to tune their optical and electronic properties by controlling their size, morphology, surface functionality and composition, still insufficient understanding is at their disposal to design and achieve well-defined and high quality Ge nanostructures for the targeting applications. Nanogermanium is a material that has great potential for technological applications and doped and alloyed Ge nanocrystals (NCs) are actively being considered. The presented work is focused on the microwave-assisted solution-based synthesis of germanium nanocrystals with insights to their formation, manipulating their composition using Group V element and achieving a better understanding of the synthetic chemistry of these materials.Chapter 1 provides an overview of fundamental concepts in the synthesis, nucleation, growth processes, surface chemistry and composition manipulation of NCs and in particular, germanium nanocrystals (Ge NCs). Chapter 2 presents the incorporation of bismuth (Bi), an n-type dopant, within or at the surface of Ge NCs. Bi classically shows no solubility in crystalline Ge. However, Ge could be doped kinetically with Bi in the nanoregime. The first colloidal synthesis in a microwave-assisted solution route and characterization of Bi-doped Ge NCs have been presented. The oleylamine capping ligand can be replaced by dodecanethiol without loss of Bi. A positive correlation between the lattice parameter and the concentration of Bi content (0.5 - 2.0 mol %) has been shown via PXRD and SAED. XPS, TEM, STEM and ICP-MS are consistent with the Bi solubility up to 2 mol %. The NC size increases with increasing amount of bismuth iodide employed in the reaction. Absorption data show that the band gap of the Bi-doped Ge NCs is consistent with the NC size. This work shows that a new element can be doped into Ge NCs via a microwave-assisted route in amounts as high as 1-2 mol % and leads to increased carriers. Colloidal chemistry provides an inroad to new materials not accessible via other means. Chapter 3 discusses a finer control of absolute size and crystallinity that can be achieved by the addition of molecular iodine (I2) and bromine (Br2) to germanium(II) iodide (GeI2). I2 and Br2 are shown to oxidize GeI2 to GeI4 in-situ, providing good control over size and crystallinity. The kinetics of Br2 oxidation of GeI2 are slightly different, but both I2 and Br2 provide size control of the Ge NCs. The samples are highly crystalline as indicated by powder X-ray diffraction (PXRD), selected area electron diffraction (SAED), transmission electron microscopy (TEM), and Raman spectroscopy. The solutions of I2, GeI2, and colloidal Ge NCs were investigated with Fourier- transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) and showed no evidence for imine, hydrazine, or nitrile formation. Hydrogen and ammonia gases were detected after the reaction by gas chromatography (GC) and high-resolution mass spectrometry (HRMS). The presence of a germanium amine iodide complex was also confirmed with no evidence for a hydrazine-like species. These results suggest an efficient fine-tuning of size and crystallinity of Ge NCs using halogens in addition to the mixed-valence precursor synthetic protocol previously reported. Chapter 4 considers Bi halide precursors (BiCl3 and BiBr3) along with an organobismuth precursor (Bi(OTf)3 for their impact on size control of Bi-doped Ge NCs. In this work, using Bi halide precursors regardless of halide anion nature alters the NCs size. Higher precursor concentration also results in greater anisotropy in morphology. While BiI3 compared to BiCl3 and BiBr3 provides larger NCs sizes, especially in high concentration regime, all three halide precursors lead to size variation. However, using the organobismuth Bi(OTf)3 as a precursor maintains a relatively constant absolute size of the Ge NCs with low Bi precursor concentrations (0.0-1.0 mol %) and more significant changes can be observed with higher Bi content. The successful incorporation of Bi using Bi(OTf)3 into Ge NCs was determined by elemental mapping performed using scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDS). It shows using the organobismuth precursor (Bi(OTf)3) promises to prevent a dramatic change of NCs sizes even when varying precursor concentration which is of paramount importance for many applications requiring a narrow and uniform size regime of doped Ge NCs. Finally, Chapter 5 presents the composition manipulation of Ge NCs, with another n-type group V element, antimony (Sb), a more common dopant for different semiconductor materials. Sb shows negligible solubility in bulk Ge, however, the kinetically controlled colloidal synthesis allows it to be incorporated in Ge or to reside on its surface. Oleylamine (OAm), OAm-trioctylphosphine (TOP)-capped Sb-doped Ge NCs have been synthesized for the first time by a microwave-assisted colloidal route. An enhancement of the lattice parameter of Ge NCs with increasing Sb concentration (0.0-1.0 mol %) is observed by PXRD. An increase in NCs diameters with higher content of SbI3 is shown by TEM. XPS and EDS confirm the presence of Sb before and after removal of OAm, TOP through hydrazine treatment and exchanging the Ge NCs surface with dodecanethiol suggesting either a strong Sb interaction with Ge surface or its incorporation within the lattice. Passivating the Ge surface by a binary ligand system of OAm, TOP results in formation of consistently larger NCs compared to OAm only. The TOP coordination to the Ge surface is confirmed by 31P NMR and SEM-EDS measurement. This Chapter presents successful synthesis of Sb-doped Ge NCs through colloidal chemistry and opens up new pathways to expand the composition chemistry of group IV semiconducting materials.

Download or read book Fundamentals and Supercapacitor Applications of 2D Materials written by Chandra Sekhar Rout and published by Elsevier. This book was released on 2021-05-04 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals and Applications of Supercapacitor 2D Materials covers different aspects of supercapacitor 2D materials, including their important properties, synthesis, and recent developments in supercapacitor applications of engineered 2D materials. In addition, theoretical investigations and various types of supercapacitors based on 2D materials such as symmetric, asymmetric, flexible, and micro-supercapacitors are covered. This book is a useful resource for research scientists, engineers, and students in the fields of supercapacitors, 2D nanomaterials, and energy storage devices. Due to their sub-nanometer thickness, 2D materials have a high packing density, which is suitable for the fabrication of highly-packed energy supplier/storage devices with enhanced energy and power density. The flexibility of 2D materials, and their good mechanical properties and high packing densities, make them suitable for the development of thin, flexible, and wearable devices. Explores recent developments and looks at the importance of 2D materials in energy storage technologies Presents both the theoretical and DFT related studies Discusses the impact on performance of various operating conditions Includes a brief overview of the applications of supercapacitors in various industries, including aerospace, defense, biomedical, environmental, energy, and automotive

Download or read book Metal and Semiconductor Nanocrystals written by Jing Zhao and published by Frontiers Media SA. This book was released on 2020-01-14 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Silicon and Germanium Nanostructures written by Xiaotang Lu and published by . This book was released on 2015 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: A variety of chemical routes exist for a wide range of nanomaterials with tunable size, shape, composition and surface chemistry. Of these materials, silicon (Si) and germanium (Ge) nanomaterials have been some of the most challenging to synthesize. Solution-liquid-solid (SLS) growth of Si was studied using tin (Sn) as the seeding metal. Si nanorods with narrow diameters can be grown by the decomposition of trisilane in hot squalane in the presence of Sn nanocrystals. Photoluminescence could be obtained from the Si nanorods by thermal hydrosilylation passivation. This colloidal synthesis could be further simplified to a single-step reaction procedure by the in situ formation of Sn seed particles. In addition to trisilane as a Si source, isotetrasilane, neopentasilane and cyclohexasilane were studied for Si nanorod growth: all three reactants enabled nanorod formation at lower growth temperatures. A monophenylsilane (MPS) enhanced growth was discovered for supercritical fluid-liquid-solid (SFLS) growth of Ge nanowires that enables the Ge conversion of ~100%. A variety of metalorganic compounds were studied for replacing pre-synthesized metal nanoparticles to induce Ge nanowire growth. Si and Ge nanowires are some of the most promising anode materials in lithium ion batteries (LIBs) because of their high lithium storage capacity. However, the significant chemical and physical changes that occur during cycling hamper their practical uses. In situ transmission electron microscopy (TEM) techniques were conducted to observe and understand structural and interfacial changes of the Si and Ge nanowires during electrochemical cycling; and, therefore, resolving the problems with current anodes by materials modification. The in situ TEM experiments showed that the incorporation of Sn into Si nanowires can enhance their rate capability. But the enhanced Li diffusion leads to the premature pore formation in Si nanowires. Ge nanowires has been discovered the potential as sodium ion battery anodes after an initial activation with a lithiation step to amorphize the nanowires.

Download or read book Synthesis and Characterization of Germanium Nanocrystals and Insights Into Their Formation written by Alexandra Lauren Holmes and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Group IV nanomaterials are of interest for a variety of applications that rely on their size dependent characteristics. A fundamental understanding of the optical and electronic properties of these nanomaterials is crucial for application. Recent interest in germanium (Ge) and Ge-based nanomaterials has grown due to advances of size, shape, and compositional control obtained from the reduction of Ge iodides in amine solvents. In Chapter 1 a brief overview of solution-based Ge nanocrystal (NC) synthesis and ligand exchange is provided. The use of microwave irradiation for NC synthesis is discussed. Cyclic voltammetry is introduced as a method to characterize the electronic bandgap of NCs. Chapter 2 discusses the microwave-assisted, solution-based synthesis of Ge NCs. Cyclic voltammetry and optical absorption were used to investigate the absolute band energies of Ge NCs of different sizes and capping ligands. As shown for other NC compositions, the ligand identity plays a role in the electronic properties of the quantum confined Ge NCs. Notably, redox active ligands were utilized to understand how the NC affects the properties of the ligand and vice versa. Chapter 3 investigates the mechanistic role of iodine in the synthesis of Ge NCs and the effect of iodine on the production of Ge NC from either Ge(II) or Ge(IV) iodides is amine solvents. It was demonstrated that iodine mediates size control though the in situ oxidation of Ge(II) iodide. Iodine was also shown to react with Ge(IV) iodide to form Ge NC aggregates. In Chapter 4, disulfides are considered as molecular precursors and as surface ligands. It was shown that there is a change in Ge NC size upon the addition of different disulfides to the reaction of Ge(II) iodide in oleylamine. Additionally, several methods of ligand exchange were tested for passivation of the Ge NC surface with disulfide reagents.

Download or read book Emerging Photovoltaic Materials written by Santosh K. Kurinec and published by John Wiley & Sons. This book was released on 2018-11-30 with total page 828 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the recent advances in photovoltaics materials and their innovative applications. Many materials science problems are encountered in understanding existing solar cells and the development of more efficient, less costly, and more stable cells. This important and timely book provides a historical overview, but concentrates primarily on the exciting developments in the last decade. It includes organic and perovskite solar cells, photovoltaics in ferroelectric materials, organic-inorganic hybrid perovskite, materials with improved photovoltaic efficiencies as well as the full range of semiconductor materials for solar-to-electricity conversion, from crystalline silicon and amorphous silicon to cadmium telluride, copper indium gallium sulfide selenides, dye sensitized solar cells, organic solar cells, and environmentally-friendly copper zinc tin sulfide selenides.

Download or read book Synthesis of Nanomaterials written by S. Noor Mohammad and published by Springer Nature. This book was released on 2020-10-27 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with the synthesis of nanomaterials with a strong focus on the underlying reaction kinetics and various synthesis mechanisms. It gives a detailed description of all major synthesis routes of many types of novel nanomaterials including nanowires, carbon nanotubes, semiconductor nanotubes, carbon nanobelts, nanofibers, nanorings, nanodots and quantum dots. In addition, it articulates the fundamental mechanisms of nanomaterials synthesis via vapor-phase, liquid-phase and solid-phase processes, highlighting the various strengths and weaknesses of each mechanism. This monograph provides the reader with a thorough review of the known state-of-the-art, along with a detailed comparison and analysis of all possible nanomaterials synthesis mechanisms. An important element of the book is how to obtain critical knowledge for controlling the morphology of nanomaterials and thereby fine tune their materials properties. The book is an ideal guide for graduate students and researchers new to the field seeking to establish or enhance their understanding of the physical and chemical fundamentals of nanomaterials synthesis mechanisms.

Download or read book Comprehensive Nanoscience and Technology written by and published by Academic Press. This book was released on 2010-10-29 with total page 2785 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the Introduction: Nanotechnology and its underpinning sciences are progressing with unprecedented rapidity. With technical advances in a variety of nanoscale fabrication and manipulation technologies, the whole topical area is maturing into a vibrant field that is generating new scientific research and a burgeoning range of commercial applications, with an annual market already at the trillion dollar threshold. The means of fabricating and controlling matter on the nanoscale afford striking and unprecedented opportunities to exploit a variety of exotic phenomena such as quantum, nanophotonic and nanoelectromechanical effects. Moreover, researchers are elucidating new perspectives on the electronic and optical properties of matter because of the way that nanoscale materials bridge the disparate theories describing molecules and bulk matter. Surface phenomena also gain a greatly increased significance; even the well-known link between chemical reactivity and surface-to-volume ratio becomes a major determinant of physical properties, when it operates over nanoscale dimensions. Against this background, this comprehensive work is designed to address the need for a dynamic, authoritative and readily accessible source of information, capturing the full breadth of the subject. Its six volumes, covering a broad spectrum of disciplines including material sciences, chemistry, physics and life sciences, have been written and edited by an outstanding team of international experts. Addressing an extensive, cross-disciplinary audience, each chapter aims to cover key developments in a scholarly, readable and critical style, providing an indispensible first point of entry to the literature for scientists and technologists from interdisciplinary fields. The work focuses on the major classes of nanomaterials in terms of their synthesis, structure and applications, reviewing nanomaterials and their respective technologies in well-structured and comprehensive articles with extensive cross-references. It has been a constant surprise and delight to have found, amongst the rapidly escalating number who work in nanoscience and technology, so many highly esteemed authors willing to contribute. Sharing our anticipation of a major addition to the literature, they have also captured the excitement of the field itself in each carefully crafted chapter. Along with our painstaking and meticulous volume editors, full credit for the success of this enterprise must go to these individuals, together with our thanks for (largely) adhering to the given deadlines. Lastly, we record our sincere thanks and appreciation for the skills and professionalism of the numerous Elsevier staff who have been involved in this project, notably Fiona Geraghty, Megan Palmer and Greg Harris, and especially Donna De Weerd-Wilson who has steered it through from its inception. We have greatly enjoyed working with them all, as we have with each other.

Download or read book Solution Preparation of Quantum confined Germanium Nanoparticles and Their Characterization written by Boyd Rex Taylor and published by . This book was released on 1999 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Emerging Materials for Sustainable Energy written by Naveen V. Kulkarni and published by Elsevier. This book was released on 2024-02-28 with total page 1034 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Emerging Materials for Sustainable Energy provides a comprehensive accounting on the fundamentals, current developments, challenges and future prospects of emerging materials for the development of sustainable energy. Each chapter addresses a distinct and important area within the energy field and includes comprehensive data to support the materials being presented. Sections cover Batteries, Capacitors and Supercapacitors, Fuel cells, Thermoelectrics, Novel illumination sources and techniques, Photovoltaics & Solar cells, Alternative energy sources, hydrogen as an energy source, including hydrogen production and fuel generation, the use of Biofuels and Carbon dioxide. The book concludes with three chapters related to advanced materials under development for energy conservation and environmental protection, including theories, methodologies and simulations established for advanced materials. Covers a broad scope of advanced materials that have been developed for energy and environmental sustainability Provides detailed and updated information about the structural and functional features of various emerging materials and their multifaceted applications Includes supplementary data alongside each chapter

Download or read book Synthesis and Characterization of Germanium Tin and Manganese Phenylphosphonates written by David E. Lansky and published by . This book was released on 2001 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of Ge Nanoparticles for Flexible Thin film Photovoltaics written by Hsiang Wei Chiu and published by . This book was released on 2005 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Halide Perovskites written by Tze-Chien Sum and published by John Wiley & Sons. This book was released on 2019-03-25 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Real insight from leading experts in the field into the causes of the unique photovoltaic performance of perovskite solar cells, describing the fundamentals of perovskite materials and device architectures. The authors cover materials research and development, device fabrication and engineering methodologies, as well as current knowledge extending beyond perovskite photovoltaics, such as the novel spin physics and multiferroic properties of this family of materials. Aimed at a better and clearer understanding of the latest developments in the hybrid perovskite field, this is a must-have for material scientists, chemists, physicists and engineers entering or already working in this booming field.