Download or read book Synthesis and Characterization of Nc Ge Using Ion Beam Techniques written by Srinivasa Rao Nelamarri and published by LAP Lambert Academic Publishing. This book was released on 2011-09 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present book deals with the synthesis and characterization of Germanium (Ge) nanocrystals prepared by using various deposition methods, annealing processes and swift heavy ion irradiation. Even though different methods have been used to prepare Ge nanocrystals, researchers are looking for more compact and versatile synthesis methods for various industrial applications. Here, we have used Atom Beam Sputtering (ABS), RF sputtering and ion implantation for initial depositions. Subsequently these as-deposited samples were annealed at various temperatures using normal furnace annealing, rapid thermal annealing (RTA), microwave annealing and irradiated with swift heavy ions of various energies and fluences for crystallization. Advantages and limitations of these techniques have been discussed in detail.

Download or read book Phase and Shape Evolutions of Ion Beam Synthesized Ge Based Nanostructures written by Swanee Shin and published by . This book was released on 2009 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Synthesis and characterization of Ge based nanostructures are presented. Ion beam synthesis of pure Ge nanocrystals by 74Ge+ implantation into a silica matrix is presented and the strategy to narrow the size distribution by controlling the substrate temperature during implantation is discussed. The size distribution of the sputter synthesized Ge nanocrystals is compared with that of ion beam synthesized Ge nanocrystals. Co-implantation of 74Ge and 120Sn forms binary eutectic alloy nanocrystals. The morphology of the nanocrystals is characterized with transmission electron microscopy and the thermodynamic implication of the equilibrium shape is discussed. It is demonstrated that nanocrystals with a metastable state can be formed with a single excimer laser pulse. The detailed structures and crystallinity of both equilibrium and metastable states are characterized using Raman spectroscopy, scanning transmission electron microscopy, and extended x-ray absorption fine structure spectroscopy. Initial composition dependent recovery of the equilibrium crystalline state upon heating of the metastable structure is investigated with ex-situ Raman spectroscopy and in-situ transmission electron microscopy equipped with a heating stage. The observed temperature tuning range extends from near room temperature to over 500 0C depending on the Sn content, indicating metal mediated lowering of the crystallization temperature. The phase maps of each phase transformation step of the GeSn alloy nanocrystals are shown using energy filtered transmission electron microscopy, and the position shift of the bulk plasmon peak is demonstrated. One dimensional binary eutectic alloy nanostructures, GeAu nanowires, are also synthesized and characterized. In GeAu nanowires, composition dependent post-growth engineering produced various types of morphologies due to the effectively infinite length for atomic diffusion in one direction. The possibility of creating nanostructures with a combination of ion beam implantation and electron beam irradiation is visited and remaining issues are discussed.

Download or read book Synthesis and Characterization of Embedded Ge Nanocrystals written by Qing Xu and published by . This book was released on 2006 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structural and Optical Characterization of Ion Beam Synthesized Ge Nanocrystals written by Ian David Sharp and published by . This book was released on 2006 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ion Beam Synthesis of Ge Nanowires written by Torsten Müller and published by . This book was released on 2001 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nano scale Materials written by S. N. Sahu and published by Nova Publishers. This book was released on 2006 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nano-Scale Materials - From Science to Technology

Download or read book Swift Heavy Ions for Materials Engineering and Nanostructuring written by Devesh Kumar Avasthi and published by Springer Science & Business Media. This book was released on 2011-05-24 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ion beams have been used for decades for characterizing and analyzing materials. Now energetic ion beams are providing ways to modify the materials in unprecedented ways. This book highlights the emergence of high-energy swift heavy ions as a tool for tailoring the properties of materials with nanoscale structures. Swift heavy ions interact with materials by exciting/ionizing electrons without directly moving the atoms. This opens a new horizon towards the 'so-called' soft engineering. The book discusses the ion beam technology emerging from the non-equilibrium conditions and emphasizes the power of controlled irradiation to tailor the properties of various types of materials for specific needs.

Download or read book Synthesis and Characterization of Ge Nanocrystals for Thin Film Applications written by and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors have developed a new route for the synthesis of alkyl terminated Germanium (Ge) nanoparticles. These nanoparticles are stable and uniform in size. This is an important first step for determining how to prepare a Ge film from Ge nanoparticles. Preliminary TEM indicates that the melting point of the Ge nanoparticles will be significantly lower than that of the bulk (937 degrees C). Once the melting point is known, the authors can experiment with polymeric substrates for the preparation of Ge films with the ultimate goal of producing flexible GaAs-based solar panels. These are expected to be lightweight, high power density solar panels that would be useful for space applications. (3 figures, 12 refs.).

Download or read book Study the Structural Properties of Ge Nanoparticles Formed by Ion Implantation and Thermal Annealing in Nitride base Dielectric Matrices written by Sahar Mirzaei and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigates the formation of Ge nanoparticles (NPs) in amorphous Si3N4 and SiOxNy by ion implantation and thermal annealing. The structural properties of the NPs were determined using a combination of laboratory and synchrotron based techniques including cross-section transmission electron microscopy (TEM), x-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), Raman spectroscopy measurements and x-ray absorption spectroscopy (XAS). The motivation for this research is that NPs synthesized from Group IV semiconductors, including Ge, show potential for novel electronic and optoelectronic devices. Ge was chosen as the material for this study, mainly due to its very large bulk exciton Bohr radius (Rb̃ 10 nm) and consequently small R/Rb ratio (where R is the NP radius), which increases the quantum confinement regime for optoelectronic applications. Also, Ge NPs embedded in thin dielectric films have exhibited impressive charge storage capabilities, useful in non-volatile memory (NVM) applications. While many studies have focused on the SiO2 matrix, there have been few experimental studies on the growth of Ge NPs in a silicon nitride and silicon oxynitride matrices. The main focus of this project was on the formation of Ge NPs in different Si3N4-based matrices and examining the short range atomic structure of embedded NPs as function of NP size using extended x-ray absorption fine structure (EXAFS). Specifically, four different matrices have considered: PECVD Si3N4, LPCVD Si3N4, PECVD SiO1.67N0.14 and PECVD SiO1.12N0.37. Size evolution and structural properties of NPs were examined as function of implantation conditions and the host matrix. Ge NPs were formed in plasma enhanced chemical vapour deposition (PECVD) Si3N4. Precipitations occurred for Ge concentrations of ≥6 at.%, which suggests the solubility limits of this order. NP size was influenced by Ge concentration and annealing temperature. NP size increased from 2.4 to 4 nm - for samples annealed at 900oC for 1 hour- when concentration was increased from 9 to 12 at.%. Moreover, as annealing temperature was increased from 700 to 900 oC NP size increased from 3 to 4.5 nm (for 12 at.% Ge samples). In general NP diameters were much small compared to SiO2 matrix due to the N content of the system, low diffusivity and large interfacial energy between Ge atoms and Si3N4-based matrices. Unlike PECVD Si3N4, ion beam synthesis of Ge in LPCVD Si3N4 layers resulted in the formation of SiGe NPs. NP size altered from 2.8 to 3.2 nm for 12 at.% Ge concentration samples after annealing temperature was increased from 700 to 900oC. Also, NP size increased from 2.3 to 3.2 nm for samples annealed at 900oC for 1 hour when Ge concentration was increased from 9 to 12 at.%. Complementary XAS techniques (in particular EXAFS), allowed us a precise and better understanding of the structure of embedded SiGe NPs. Since the lattice difference between Ge and SiGe NPs (less than 4%) could not be distinguished by TEM. A phase transition of the matrix was observed for LPCVD and PECVD Si3N4 matrices after annealing at 1100 oC. This significantly lowered crystallization temperature of un-implanted layers (1600-1800oC). Formation of nanosilicide particles, change of stoichiometry and implantation induced-damage are found to be the most likely causes of crystallization. Ge NPs were formed in SiO1.67N0.14 matrix for different Ge concentrations and annealing temperatures. For Ge concentrations from 9 to 12 at.% annealed at 900oC for 1 hour, NP size increased from 3.7 to 4.5 nm. Also, when annealing temperature was increased from 700 to 900oC NP size increased from 4.1 to 4.5 for 12 at.% Ge concentration. We observed that slight amount of the N in the system had a significant effect on NP size similar to PECVD Si3N4. Unlike other examined systems, cavities were formed near the implanted region in SiO1.12N0.37 matrix for different concentrations and annealing temperatures, which could be correlated to the matrix structure and composition or vacancy events after ion implantation. The size, origin and properties of formed cavities are subjects of future work. No phase transition (or long-range diffusivity of Ge atoms) was observed for SiOxNy matrices after annealing at 1100 oC.

Download or read book Nuclear Instruments Methods in Physics Research written by and published by . This book was released on 2001 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metal Oxides for Non volatile Memory written by Panagiotis Dimitrakis and published by Elsevier. This book was released on 2022-03-01 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal Oxides for Non-volatile Memory: Materials, Technology and Applications covers the technology and applications of metal oxides (MOx) in non-volatile memory (NVM) technology. The book addresses all types of NVMs, including floating-gate memories, 3-D memories, charge-trapping memories, quantum-dot memories, resistance switching memories and memristors, Mott memories and transparent memories. Applications of MOx in DRAM technology where they play a crucial role to the DRAM evolution are also addressed. The book offers a broad scope, encompassing discussions of materials properties, deposition methods, design and fabrication, and circuit and system level applications of metal oxides to non-volatile memory. Finally, the book addresses one of the most promising materials that may lead to a solution to the challenges in chip size and capacity for memory technologies, particular for mobile applications and embedded systems. Systematically covers metal oxides materials and their properties with memory technology applications, including floating-gate memory, 3-D memory, memristors, and much more Provides an overview on the most relevant deposition methods, including sputtering, CVD, ALD and MBE Discusses the design and fabrication of metal oxides for wide breadth of non-volatile memory applications from 3-D flash technology, transparent memory and DRAM technology

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 The Synthesis and Characterization of Germanium Nanoparticles and Nanowires and the Study of Their Potential in Photovoltaics written by Stephen Corey Codoluto and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increasing energy demand of an overpopulated society has bolstered the interest in exploring renewable energy forms, one of which is solar energy. Current solar cell technology is neither an efficient nor cost-effective alternative to currently used fossil fuels. Nanostructured semiconductor building blocks are expected to play a central role in the development of next-generation cost-effective solar cell technology. Among the various materials that have been explored and studied, Ge holds particular promise due to it favorable band gap and good transport characteristic. A method to produce colloidal Ge nanocrystals, however, has not yet been established. Colloidal synthesis provides a scalable and cost-effective route to nanocrystalline semiconductor material as building blocks in low-cost PV energy conversion devices. This work describes the synthesis and characterization of Ge nanoparticles and Ge nanowires and their potential applications. Ge nanoparticles, 1.9 - 16.0 nm, are synthesized via colloidal synthesis by reducing germanium iodide using a strong reducing agent in various coordinating solvents. The effects of reaction and injection temperature, reaction time, and initial concentration are studied. A minimum temperature of 250 °C is required to crystallize Ge in a colloidal synthesis, below which only amorphous material is formed. An increase in reaction temperature from 250 to 300 °C has little effect on the final nanocrystal size and structure. A temperature of 200 °C was found to minimize crystal growth defects. Increasing or decreasing the injection temperature increased the crystal defects. The final crystalline products are analyzed using XRD, FTIR, TEM, HR-TEM, SEM, UV-vis spectroscopy, and PL to study oxidation, crystal structure, and optical properties. Spin coated germanium nanoparticles are combined with sputtered a-Si to create a polysilicon-Ge matrix which could direct charge transfer and decrease recombination of photogenerated charges. As a complementary nanocrystalline Ge building block nanowires were also synthesized by the thermal decomposition of DPG and TMG in supercritical hexane using a batch and a semicontinuous supercritical reactor. Up to 210 mg are synthesized and collected using this process with a diameter range of 20 nm to 60 nm and lengths up to 15 [MICRO SIGN]m. The continuously grown nanowire experimental yield is ~35%, compared to the batch experimental yield of 15%. The Ge nanowires were easily extracted from the collection vessel and characterized using TEM, SEM, and XRD to confirm the presence of Ge and to study the structure of the wires.

Download or read book Protective Coatings and Thin Films written by Y. Pauleau and published by Springer Science & Business Media. This book was released on 1996-12-31 with total page 694 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume entitled "Protective Coatings and Thin Films : Synthesis, Characterization and Applications" contains the Proceedings of the NATO Advanced Research Workshop (ARW) held in Alvor, Portugal from May 30 to June 5, 1996. This NATO-ARW was an expert meeting on the surface protection and modification of solid materials subjected to interactions with the environment. The meeting attracted 10 key speakers, 40 contributing speakers and 3 observers from various countries. The existing knowledge and current status of the science and technology related to protective coatings and thin films were assessed through a series of oral presentations, key notes (titles underlined in the volume content) and contributed papers distributed over various sessions dealing with: (a) plasma-assisted physical and chemical vapor deposition processes to enhance wear and corrosion protection of materials, (b) low friction coatings operating in hostile environment (vacuum, space, extreme temperatures, . . . ), (c) polymer films for protection against mechanical damage and chemical attack, (d) characterization of the structure of films and correlations with mechanical properties, (e) wear and corrosion resistant thermal spray coatings, (f) functional gradient ceramic/metallic coatings produced by high energy laser beam and energetic deposition processes for high temperature applications, (g) protective coatings for optical systems, and (h) ion beam assisted deposition of coatings for protection of materials against aqueous corrosion.

Download or read book Nanocrystals in Nonvolatile Memory written by Writam Banerjee and published by CRC Press. This book was released on 2024-08-09 with total page 683 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, the abundant advantages of quantum physics, quantum dots, quantum wires, quantum wells, and nanocrystals in various applications have attracted considerable scientific attention in the field of nonvolatile memory (NVM). Nanocrystals are the driving elements that have helped nonvolatile flash memory technology reach its distinguished height, but new approaches are still needed to strengthen nanocrystal-based nonvolatile technology for future applications. This book presents comprehensive knowledge on nanocrystal fabrication methods and applications of nanocrystals in baseline NVM and emerging NVM technologies and the chapters are written by experts in the field from all over the globe. The book presents a detailed analysis on nanocrystal-based emerging devices by a high-level researcher in the field. It has a unique chapter especially dedicated to graphene-based flash memory devices, considering the importance of carbon allotropes in future applications. This updated edition covers emerging ferroelectric memory device, which is a technology for the future, and the chapter is contributed by the well-known Ferroelectric Memory Company, Germany. It includes information related to the applications of emerging memories in sensors and the chapter is contributed by Ajou University, South Korea. The book introduces a new chapter for emerging NVM technology in artificial intelligence and the chapter is contributed by University College London, UK. It guides the readers throughout with appropriate illustrations, excellent figures, and references in each chapter. It is a valuable tool for researchers and developers from the fields of electronics, semiconductors, nanotechnology, materials science, and solid-state memories.

Download or read book Growth and Characterization of GE Nanocrystals written by and published by . This book was released on 1998 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have synthesized Ge nanocrystals of sizes 4, 8, and 12 nm by ion-implanting Ge+ ions into thermally grown Si02 films and subsequent annealing of the films at 8300 C for 30 min in nitrogen. These films were characterized by x-ray, transmission electron microscopy (TEM), and Raman spectroscopy. A distribution of particle size was identified by TEM in a 1 00 nm band below the surface. Particle sizes were estimated by these 3 techniques.