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1
Zhang, Xuefei. "Synthesis and Characterization of Zr1-xSixN Thin Film Materials." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/ZhangX2007.pdf.
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Grenier, Serge. "Large scale carbothermal synthesis of submicron silicon nitride powder." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61211.
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The synthesis of silicon nitride (Si$ sb3$N$ sb4$) by carbothermal reduction of silica was sensitive to the processing steps used for the starting materials (SiO$ sb2$, C) and to the reaction conditions. A good degree of intimacy between the starting materials was required in order to obtain fine ceramic powders.The formation of Si$ sb3$N$ sb4$ was known to occur over a narrow temperature range (1450-1550$ sp circ$C). The morphology of the silicon nitride powder produced was also shown to vary widely depending on the reaction temperature.
The amount and morphology of the silicon carbide formed was sensitive to impurities present in the precursors prior to the reaction. The nitrogen flow rate during reaction as well as the position of pellets in the reactor played a key role in the final SiC content of the powder.
Results showed that the strength values of two carbothermal powders were excellent (507 and 577 MPa) considering their lower sintered densities which was the result of residual carbon present in the powder. (Abstract shortened by UMI.)
3
Middlemas, Michael Robert. "Fabrication, strength and oxidation of molybdenum-silicon-boron alloys from reaction synthesis." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28253.
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Thesis (M. S.)--Materials Science and Engineering, Georgia Institute of Technology, 2009.Committee Chair: Cochran, Joe; Committee Member: Berczik, Doug; Committee Member: Sanders, Tom; Committee Member: Sandhage, Ken; Committee Member: Thadhani, Naresh.
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Vemuri, Prasanna. "Synthesis of cubic boron nitride thin films on silicon substrate using electron beam evaporation." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc5542/.
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Cubic boron nitride (cBN) synthesis has gained lot of interest during the past decade as it offers outstanding physical and chemical properties like high hardness, high wear resistance, and chemical inertness. Despite of their excellent properties, every application of cBN is hindered by high compressive stresses and poor adhesion. The cost of equipment is also high in almost all the techniques used so far. This thesis deals with the synthesis of cubic phase of boron nitride on Si (100) wafers using electron beam evaporator, a low cost equipment that is capable of depositing films with reduced stresses. Using this process, need of ion beam employed in ion beam assisted processes can be eliminated thus reducing the surface damage and enhancing the film adhesion. Four sets of samples have been deposited by varying substrate temperature and the deposition time. scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) techniques have been used to determine the structure and composition of the films deposited. X-ray diffraction (XRD) was performed on one of the samples to determine the thickness of the film deposited for the given deposition rate. Several samples showed dendrites being formed as a stage of film formation. It was found that deposition at substrate temperature of 400oC and for a period of one hour yielded high quality cubic boron nitride films.
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Jordan, Jennifer Lynn. "Shock-activated reaction synthesis and high pressure response of Ti-based ternary carbide and nitride ceramics." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/19674.
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Lale, Abhijeet. "Synthesis and characterization of silicon and boron -based nitride nanocomposites as catalytic mesoporous supports for energy applications." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT203/document.
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La présente thèse s’inscrit dans un projet collaboratif de type CEFIPRA entre l’Inde (Dr. Ravi Kumar, Department of Metallurgical and Materials Engineering, Indian Institute of Technology-Madras (IIT Madras), Chennai) et la France (Dr. Samuel Bernard, Institut Européen des Membranes, CNRS, Montpellier). Les travaux de thèses se sont consacrés à la synthèse de céramiques de type non-oxyde autour de systèmes binaires (nitrure de silicium et nitrure de bore) et ternaires (Si-M-N, B-M-N (M=Ti, Zr, Hf)) à partir de précurseurs moléculaires et polymères, i.e., la voie polymères précéramiques ou PDCs. L’idée principale de ce travail est de former des structures nanocomposites à partir des systèmes ternaires dans lesquelles des nanocristaux de nitrures métalliques (M=Ti, Zr, Hf) se développent pendant la synthèse du nitrure de silicium et du nitrure de bore. Une caractérisation complète allant des polymères aux matériaux finaux a été conduite. Ces matériaux ont ensuite été préparés sous forme de composés mésoporeux (monolithes) en couplant la voie des polymères précéramiques à une approche de nanomoulage. Ces monolithes à haute surface spécifique et mésoporosité interconnectée ont alors été appliqués comme support de nanoparticules de platine pour l’hydrolyse du borohydrure de sodium pour générer de l’hydrogène. Les performances en tant que support de catalyseur ont été évaluées en termes de volume d’hydrogène libéré et de reproductibilité. Nous avons montré que les nanocomposites TiN/Si3N4 de surface spécifique très élevée présentent les meilleures performances grâce à l’activité catalytique du Si3N4 amorphe, de la présence de TiN nanométrique et de l’effet synergétique entre les nanoparticules Pt, le TiN nanostructuré et le Si3N4 amorphe. En preuve de concept, nous avons montré que ces structures nanocomposites étaient multifonctionnelles: elles peuvent être appliquées en tant que supports d’électro-catalyseurs et matériaux d’électrodes dans les piles à combustibles et les super-condensateurs, en particulier pour ceux contenant des matériaux lamellaires 2D et du carbone libreThe thesis has been funded by a collaborative research partnership between Indian (Dr. Ravi Kumar, Department of Metallurgical and Materials Engineering, Indian Institute of Technology-Madras (IIT Madras), Chennai) and French institutes (Dr. Samuel Bernard, European Membrane Institute, CNRS, Montpellier), IFCPRA/CEFIPRA. It is focused on the synthesis, and characterization of binary (silicon nitride and boron nitride) and ternary (Si-M-N, B-M-N (M = Ti, Zr, Hf)) ceramics which are prepared through a precursor approach based on the Polymer-Derived Ceramics (PDCs) route. The idea behind the preparation of the ternary systems is to form nanocomposite structures in which metal nitrides (M = Ti, Zr, Hf) nanocrystals grow during the synthesis of silicon nitride and boron nitride. A complete characterization from the polymer to the final material is done. Then, these materials have been prepared as mesoporous monoliths coupling the PDCs route with a nanocasting approach to be applied as supports of platinum nanoparticles for the hydrolysis of liquid hydrogen carriers such as sodium borohydride. The performance as catalyst supports has been evaluated in terms of volume of hydrogen released and reproducibility. We showed that the very high specific surface area TiN/Si3N4 nanocomposites displayed the best performance because of the catalytic activity of amorphous Si3N4, the presence of nanoscaled TiN and the synergetic effect between Pt nanoparticles, nanoscaled TiN and amorphous Si3N4. Interesting, these materials are multi-functional as demonstrated as a proof of concept: they can be applied as electrocatalyst supports, electrode materials for fuel cells and supercapacitors, in particular those containing 2D layered materials and free carbon
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Abass, Monsuru A. "Boron nitride nanotube-modified silicon oxycarbide ceramic composite: synthesis, characterization and applications in electrochemical energy storage." Thesis, Kansas State University, 2017. http://hdl.handle.net/2097/35423.
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Master of ScienceDepartment of Mechanical and Nuclear Engineering
Gurpreet Singh
Polymer-derived ceramics (PDCs) such as silicon oxycarbide (SiOC) have shown promise as an electrode material for rechargeable Li-ion batteries (LIBs) owing to the synergy between its disordered carbon phase and hybrid bonds of silicon with oxygen and carbon. In addition to their unique structure, PDCs are known for their high surface area (~822.7 m² g⁻¹), which makes them potential candidates for supercapacitor applications. However, low electrical conductivity, voltage hysteresis, and first cycle lithium irreversibility have hindered their introduction into commercial devices. One approach to improving charge storage capacity is by interfacing the preceramic polymer with boron or aluminium prior pyrolysis. Recent research has shown that chemical interfacing with elemental boron, bulk boron powders and even exfoliated sheets of boron nitride leads to enhancements in thermal and electronic properties of the ceramic. This thesis reports the synthesis of a new type of PDC composite comprising of SiOC embedded with boron nitride nanotubes (BNNTs). This was achieved through the introduction of BNNT in SiOC pre-ceramic polymer at varying wt.% loading (0.25, 0.5 and 2.0 wt.%) followed by thermolysis at high temperature. Electron microscopy and a range of spectroscopy techniques were employed to confirm the polymer-to-ceramic transformation and presence of disordered carbon phase. Transmission electron microscopy confirmed the tubular morphology of BNNT in the composite. To test the material for electrochemical applications, the powders were then made into free-standing paper-like electrodes with reduced graphene oxide (rGO) acting as support material. The synthesized free-standing electrodes were characterized and tested as electrochemical energy storage materials for LIBs and symmetric supercapacitor applications. Among the SiOC-BNNT composite paper tested as anode materials for LIBs, the 0.25 wt.% BNNT composite paper demonstrated the highest first cycle lithiation capacity corresponding to 812 mAh g⁻¹ (at a current density of 100 mA g⁻¹) with a stable charge capacity of 238 mAh g⁻¹ when asymmetrically cycled after 25 cycles. On the contrary, the 0.5 wt.% BNNT composite paper demonstrated the highest specific capacitance corresponding to 78.93 F g⁻¹ at a current density of 1 A g⁻¹ and a cyclic retention of 86% after 185 cycles. This study shows that the free carbon content of SiOC-BNNT ceramic composite can be rationally modified by varying the wt.% of BNNT. As such, the paper composite can be used as an electrode material for electrochemical energy storage.
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Roussey, Arthur. "Preparation of Copper-based catalysts for the synthesis of Silicon nanowires." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10164.
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Les travaux dans cette thèse ont pour objectif la synthèse de catalyseurs (nanoparticules de cuivre) de taille contrôlée pour la synthèse de nanofils de silicium dans des conditions compatibles CMOS, c'est-à-dire en évitant l'utilisation de l'or comme catalyseur et pour des croissances basse température (<450°C). Les résultats obtenus ont permis de montrer que les techniques de chimie de surface classiquement utilisées pour la préparation de catalyseurs sur des supports 3D (silice, nitrure de titane…) sont directement applicables et transférables sur des supports 2D (wafer de silicium recouvert de films fins de SiO2, SiOx et TiN). Nous avons par exemple pu préparer des nanoparticules de cuivre de taille contrôlée (de 3 nm à 40 nm de diamètre moyen suivant les conditions expérimentales et supports). De plus, les mécanismes de formation des nanoparticules en fonction des propriétés de surface des matériaux étudiés ont été démontrés en combinant diverses techniques d'analyses de surface. La croissance de nanofils de silicium à partir de ces catalyseurs sur substrats 2D a également été réalisée avec succès dans des procédés à basse température. Il a notamment été montré l'existence d'un diamètre minimum critique à partir de laquelle la croissance basse température était possibleThe work presented in this PhD thesis aimed at the preparation of copper nanoparticles of controllable size and their utilization as catalysts for the growth of silicon nanowires in a process compatible with standard CMOS technology and at low temperature (< 450°C). The growth of silicon nanowires by Chemical Vapor Deposition (CVD) via the catalytic decomposition of a silicon precursor on metallic nanoparticles at low temperature (Vapor Solid-Solid process) was demonstrated to be possible from an oxidized Cu thin film. However, this process does not allow the control over nanowires diameter, which is controlled by the diameter of the nanoparticle of catalyst. In this PhD is presented a fully bottom-up approach to prepare copper nanoparticles of controllable size directly on a surface without the help of external stabilizer by mean of surface organometallic chemistry. First, the preparation of copper nanoparticles is demonstrated on 3D substrates (silica and titanium nitride nanoparticles), along with the fine comprehension of the formation mechanism of the nanoparticles as a function of the surface properties. Then, this methodology is transferred to planar (2D) substrates typically used in microelectronics (silicon wafers). Surface structure is demonstrated to direct the Cu nanoparticles diameter between 3 to 40 nm. The similarities between the 2D and 3D substrates are discussed. Finally, the activity of the Copper nanoparticles in the growth of Silicon nanowire is presented and it is demonstrated that in our conditions a critical diameter may exist above which the growth occurs
9
Xiao, Zhigang. "Synthesis of Functional Multilayer Coatings by Plasma Enhanced Chemical Vapor Deposition." Cincinnati, Ohio : University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1081456822.
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Shah, Syed Imran Ullah. "Synthesis of transition metal nitrides and silicon based ternary nitrides." Thesis, University of Southampton, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580538.
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Solution phase ammonolysis and sol-gel techniques that produce polymeric metal-amide precursors are of growing interest in the synthesis of nitride materials, which result from the thermal decomposition of the polymer. They can be used to control composition and to produce a large number of useful morphologies such as nanoparticles, films, monoliths, aerogels, and materials with large surface area such as foams. The synthesis of nitride materials using ammonolysis of metal amides and chlorides has so far largely focused on producing powders for applications such as catalysis, or thin films by chemical vapour deposition and related techniques. In this thesis, formation of tantalum and molybdenum nitride nanoparticles and metal-silicon nitride based nanocomposites have been synthesised using non-oxide precursors by solution phase ammonolysis and sol-gel methods respectively. For tantalum nitride nanoparticles Ta(NMe2)5 in THF was ammonolysed with ammonia at - 78 QC and the polymeric precursor was pyrolysed at various temperatures under ammonia. Amorphous TaN was obtained at 700 QC and below, while Ta3Ns was obtained at 800 QC under ammonia and also by re-annealing the amorphous samples at 800 QC under nitrogen. Molybdenum nitride powders were obtained by solution phase ammonolysis of MoCl, or Mo(NMe2)4 and further annealing the polymeric precursors on different temperatures. The chloride precursor resulted in hexagonal Mo'N, at 500 QC, or rock salt Mobl, at 700-1000 QC and mixture of both at 600 QC. The amide precursor resulted phase pure hexagonal MoNx at 600 QC and rock salt mixed with hexagonal at 1000 QC. Samples produced at 600 QC consisted mainly of nanotubes. Some decomposition to molybdenum metal was found in MoN obtained at 1000 QC from either precursor source. Co-ammonolysis of Ta(NMe2)5 or Mo(NMe2)4 with Si(NHMe)4 was carried out using sol-gel technique. Polymeric metal-silicon amide precursors were annealed at 600 or 1000 QC. The Ta/Si precursor produced amorphous nanocomposites and no phase segregation was observed even after high temperature annealing. With molybdenum the products were nanocomposites of molybdenum nitride particles, including nanotubes, supported on a silicon nitride amorphous matrix.
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Shin, Jae Ho Schoenfisch Mark H. "Synthesis and characterization of nitric oxide-releasing silica materials for sensing applications." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,593.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2006.Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry (Analytical Chemistry)." Discipline: Chemistry; Department/School: Chemistry.
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MACHADO, GLAUSON A. F. "Desenvolvimento de composito ceramico a partir de mistura de alumina e polimero pecursor ceramico polissilsesquioxano." reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9432.
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Made available in DSpace on 2014-10-09T12:26:46Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T13:59:55Z (GMT). No. of bitstreams: 0
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Qiao, Xiaoguang. "Synthesis of silica-polymer hybrid particles via controlled radical polymerization in aqueous dispersed media." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10332/document.
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Des polymères à base de méthacrylate de poly(oxyde d'éthylène) (PEOMA) avec des chaînes pendantes PEO (Mn = 300 ou 950 g mol-1) ou des copolymères de PEOMA300 et d'acide méthacrylique (AMA) ont été synthétisés par polymérisation radicalaire contrôlée par les nitroxydes en utilisant une alkoxyamine (BlocBuilder®) comme amorceur en présence de SG1 et d'une faible quantité de styrène. Les copolymères à base de PEOMA300 et d'AMA sont thermo- et pH-sensibles. Les deux types de macroalkoxyamines ont été utilisés pour amorcer la copolymérisation en émulsion du méthacrylate de n-butyle et du styrène et former, par auto-assemblage induit par la polymérisation, des particules composées de copolymères à blocs amphiphiles, en absence ou présence de particules de silice. En absence de silice, des particules stabilisées de façon stérique ou électrostérique ont été formées. La polymérisation présente les caractéristiques d'une polymérisation contrôlée avec néanmoins la formation d'une faible proportion de chaînes mortes. L'effet du pH, de la force ionique et de la nature ou de la concentration des macroalkoxyamines sur la cinétique de polymérisation et la morphologie des particules a été étudié, et des sphères, des vésicules ou des nanofibres ont été obtenues. Les macroalkoxyamines à base de PEO s'adsorbent sur la silice via la formation de liaisons hydrogène entre les chaînes PEO et les groupes silanol. La synthèse de copolymères à blocs en surface de la silice a conduit à la formation de particules hybrides de différentes morphologies (bonhomme de neige, multipodes, framboise, coeur-écorce, têtard, mille pattes) liées à la taille de la silice, au pH et à la nature du macroamorceurWater-soluble brush-type polymers composed of poly(ethylene)oxide methacrylate (PEOMA) units with PEO side groups of various chain lengths (Mn = 300 and 950 g mol-1) or of PEOMA300 with methacrylic acid (MAA) were synthesized by nitroxide-mediated polymerization using an alkoxyamine initiator (BlocBuilder®) and SG1 nitroxide in the presence of a low amount of styrene. The PEOMA300-MAA based copolymers showed a dual temperature/pH response. The two series of macroalkoxyamines were used in aqueous emulsion copolymerization of nbutyl methacrylate and styrene leading to the formation of particles composed of amphiphilic block copolymers through polymerization-induced self-assembly, in both the absence and presence of silica. The experiments performed in the absence of silica particles resulted in the formation of sterically or electrosterically stabilized latexes. The polymerization exhibited all the features of a controlled system with however the presence of a small proportion of dead chains. The effect of pH value, ionic strength and type and concentration of the macroalkoxyamine initiator on polymerization kinetics and latex morphologies was investigated. Depending on the reaction conditions, spherical particles, vesicles or nanofibers were successfully prepared. The PEO-based macroalkoxyamines were shown to adsorb on the silica surface via hydrogen bond interaction between PEO and the silanol groups. This enabled block copolymers to be generated in situ on the silica surface leading to hybrid particles with snowman, raspberry, daisy, core-shell, “tadpole-” and “centipede-” like morphologies depending on the silica particle size, pH value and type of macroinitiator
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Rogler, Daniela. "Entwicklung einer lichtbogengestützten PECVD-Technologie für die Synthese siliziumbasierter Schichtsysteme unter Atmosphärendruck – Untersuchung des diffusionslimitierten Wachstumsregimes." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-97547.
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Atmosphärendruckplasmen sind aufgrund ihrer vergleichsweise einfachen Anlagentechnik, potentiell geringen Betriebs- und Investitionskosten sowie ihrer Flexibilität bezüglich Substratgröße seit vielen Jahren von großem Interesse. Die Nutzung von Plasmaquellen mit hoher Precursoranregungseffizienz und ausgedehnter Beschichtungszone ist in diesem Zusammenhang besonders vorteilhaft. In der vorliegenden Arbeit wird deshalb erstmals eine neuartige Langlichtbogenplasmaquelle vom Typ LARGE (Long Arc Generator) zur plasmagestützten Synthese von Schichten bei AP (Atmosphärendruck) eingesetzt. Bei der Remoteaktivierung des Precursors erweisen sich insbesondere sauerstoff- sowie stickstoffhaltige Plasmagase als geeignet, um einen signifikanten Anteil der Plasmaenergie in den Remotebereich zu transferieren. Die entwickelte bogenbasierten PECVD (Plasma Enhanced Chemical Vapour Deposition) unter Atmosphärendruckbedingungen ist durch die Erzeugung hochenergetischer Plasmen gekennzeichnet, der Precursor wird stark fragmentiert und ursprüngliche Bindungen des Precursormoleküls werden vollkommen aufgebrochen.
Die Ergebnisse der Gasphasencharakterisierung mittels optischer Emissions- sowie Infrarotspektroskopie lassen beim Prozess der Precursorfragmentierung im Remoteplasma auf eine zentrale Bedeutung metastabiler sowie dissoziierter Spezies schließen. Weiterhin sind hohe Plasmaleistungen, Molekulargasanteile im Plasmagas und große Plasmagasflüsse für eine wirkungsvolle Remoteaktivierung des Precursors von Vorteil. Einen wichtigen Aspekt des Verfahrens stellt darüber hinaus die Möglichkeit der Synthese sauerstofffreier Schichtmaterialien dar. Es konnte gezeigt werden, dass sowohl der genutzte Atmosphärendruckreaktoraufbau mit seinem Gasschleusenkonzept, als auch die Gasreinheit des verwendeten Prozessgases zu keiner nennenswerten Einlagerung von Sauerstoff in die Schicht führt. Die Schichthärte synthetisierter Siliziumnitrid-Schichten lässt sich ohne zusätzliche Substratheizung durch Prozessparameteroptimierung bis auf eine Härte von 17 GPa steigern. Die dynamische Abscheiderate ist mit 39 nm∙mm/s ebenfalls für eine technische Anwendung ausreichend hoch. Eine eingehende Analyse aller Daten legt den Schluss nahe, dass das Schichtwachstum bei der Atmosphärendruck Remote-PECVD häufig kinetisch gehemmt ist und nicht im thermodynamischen Gleichgewicht stattfindet. Der Wachstumsprozess ist in diesem Fall durch das Phänomen des DLG (Diffusion Limited Growth) gekennzeichnet. Homogennukleation bzw. Gasphasennukleation spielt anders als bislang angenommen auch bei Atmosphärendruckbedingungen keine bzw. eine nur untergeordnete Rolle und ist damit nicht limitierend für die erzielbare mechanische und chemische Stabilität der gebildeten Schichten. Mit steigender Diffusionslimitierung des Schichtbildungsvorganges wird eine Zunahme der Schichtrauheit beobachtet, daraus und aus dem Zuwachs an strained sowie dangling Bonds in der Schicht resultiert eine gesteigerte Affinität der synthetisierten Schichten gegenüber Sauerstoff. Als Schlüsselparameter bezüglich Schichtmorphologie sowie Topographie wird der DLG-Quotient angesehen, welcher das Verhältnis aus Oberflächendiffusionskoeffizient und Auftreffrate schichtbildender Spezies auf dem Substrat darstellt. Damit wurden im Rahmen dieser Arbeit die entscheidenden und verfahrenslimitierenden Aspekte identifiziert und die Grundlage für die weitere Optimierung dieses und anderer Remote-AP-PECVD-Verfahren geschaffen. In ähnlicher Weise wie dies auch durch die Bereitstellung einer verbesserten thermischen Aktivierung des Diffusionsprozesses schichtbildender Spezies auf der Substratoberfläche geschieht, lässt sich mit Hilfe eines niedrigen Stickingkoeffizienten eine Diffusionslimitierung des Schichtbildungsvorgangs bei AP-PECVD unterdrücken. In diesem Zusammenhang besitzt insbesondere Ammoniak im Remotegas einen günstigen Einfluss auf die entstehende Schichtmorphologie und Konformalität der Beschichtung.
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Vongpayabal, Panut. "Kinetics of nano-sized Si₃N₄ powder synthesis via ammonolysis of SiO vapor." Thesis, 2003. http://hdl.handle.net/1957/30356.
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An 89 mm-diameter vertical tubular-flow reactor was used to study the kinetics
of nano-sized silicon nitride powder synthesis via the animonolysis of SiO vapor at
temperatures ranging from 1300°C to 1400°C. The SiO generation rate was controlled
by adjusting the mass of SiO particles initially charged in the SiO generator, when the
flow rate of carrier gas argon was maintained unchanged. The molar feed ratio of
NH₃/SiO at the feeder outlets was maintained in large excess of the stoichiometric ratio
ranging from about 100 to 1200 mol NH₃/mol SiO.
The SiO-NH₃ reaction yielded two different morphologies of silicon nitride
products at different locations in the reactor: nano-sized powder with an averaged
particle size of about 17 nm and whiskers with a variety of shapes and diameters of a
few micrometers. Nano-sized powder was the dominant product in the system and its
mass fraction over the total product varied from 83% to 100%, depending on operating
conditions.
The contact pattern between SiO vapor and NH₃ inside the reacting zone was
one of the most important parameters that affected Si₃N₄ formation kinetics. When a
small single tube was employed for feeding NH₃ (flow condition J), a highest
efficiency of SiO vapor utilization was achieved at a high level of SiO conversion. The
SiO conversion increased from 72% to 91% with an increase in the residence time
from 0.17 s to 0.69 s, indicating that the SiO-NH₃ reaction was not instantaneous but
was relatively fast.
When the molar feed rate of NH₃ was 2-3 orders of magnitude greater than that
of SiO vapor, the rate of nano-sized powder synthesis was independent of NH₃
concentration and of first order with respect to the SiO concentration. A pseudo-first
order rate expression was proposed, and the apparent activation energy was determined
to be 180 kJ/mol.
The gas flow in the reactor simulated with a computational fluid dynamic
program revealed that whisker formed where the stagnation of gas flow formed. A
power law rate expression for whisker formation was proposed based on measured
rates of whisker formation and simulation-predicted reactant-gas concentrations.Graduation date: 2004
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Lin, Dah-cheng. "Kinetic study on the synthesis of Si���N��� via the ammonization of SiO vapor." Thesis, 1995. http://hdl.handle.net/1957/34606.
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Wei, Sheng Lung, and 魏聖龍. "The Synthesis and Characterization of Crystalline Silicon Carbon Nitride." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/11583489824324615498.
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碩士輔仁大學
物理學系
87
The synthesis of this hypothetical ultrahard material is of both fundamental and technological significance and presents a great challenge to condensed matter physicists, material scientists and chemists. In order to synthesize crystalline C3N4 , various methods have been adopted, and only some of them have shown successful synthesis of polycrystalline C3N4 solid with a size typically between nanometer and submicron.In contrast to the synthesis of C3N4, the growth of large (several tens of microns), well faceted Si-containing crystalline C-N solid (c-CN) has been achieved by microwave plasma-enhanced chemical vapor deposition (MW-PECVD). In order to make a further survey of the growth process window of this novel material, different kinds of synthesis techniques, such as deposition on substrates with various pretreatments, were considered to serve this purpose. Various methods of substrate pretreatments, including the enhancement of nucleation density and oriented crystallization by deposition on transition metal films and on the Si substrate scratched by Si3N4 powder in micron size, were adopted in the c-SiCN synthesis process. Furthermore, nanocrystalline silicon carbon nitride with rod-like shape has been synthesized with the assisted ECR-CVD buffer layer by two-step growth process. In the characterization of SiCN compounds, auger electron spectroscopy (AES), electron microscopy (both SEM and TEM), and X-ray photoelectron spectroscopy (XPS), have been employed to determine the composition, the morphology, the crystal structure, and the chemical binding structures of the films. Further investigation of the electronic band structure of this material was carried out with piezoreflectance (PzR) spectroscopy, photoluminescence (PL) measurement and photothermal deflection spectroscopy (PDS). It is found that the SiCN compounds have a direct band gap centered around 3.8 eV and a near band edge centered around 3.26eV at room temperature. The results of optical measurements show the potential of this wide band gap semiconductor for further optoelectronic applications.
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Lin, Hung Min, and 林宏旻. "Synthesis and characterization of novel one-dimensional nanostructures:gallium nitride and silicon dioxide." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/79394272737615817086.
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碩士國立臺灣師範大學
化學研究所
91
A simple route for the synthesis of unique 1D nanostructures, including brush-like gallium nitride nanostructure, oriented amorphous silicon nanowires and In@SiO2 nanocables, was developed on the basis of VLS and SLS mechanisms. GaN nanobrushes with geometric symmetries were fabricated via a two-step growth process. Morphological studies indicated the diameters of trunk nanowires and branch nanorods ranged from 70 to 150nm and 20 to 70nm respectively. According to crystal structure analyses, most nanobrushes exhibited single crystalline structure indexed to h-GaN and branch nanorods were epitaxially grown on trunk nanowires along direction of [01-1]. Using low-melting-point metal as catalyst, the practicability of silica nanowires grown at lower temperature was expected. Amorphous silica nanowires with diameters of 10~40nm and length of up to ~50m were formed via SLS mechanism catalyzed by molten Ga metal. Aligned nanowires with uniform length were arranged to thin film. Growth of nanowires occurred at 900℃ in spite of expect at lower temperature. However, the SLS method could be generalized to other low-melting metals, such as In, Bi and Sn, to grow aligned various nanowires. In@SiO2 nanocables were discovered accidentally as we researched in InP nanowires growth. Structural characterization revealed that nanocables composed of discontinuous crystalline In core with diameters of 200~500nm and amorphous silica shell with diameter from 300~600nm. In@SiO2 nanocables may be applied to nanoscale thermometer due to high expansion coefficient of In metal. Unique 1D nanostructures described above are expected to potential application on optoelectronics, NEMS and biochemistry.
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Lin, Rong Jing, and 林容靖. "Copper-Catalyzed Oxidative Povarov Reactions and Synthesis of Novel Precursors of Silicon Nitride Film." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/35354503763208539699.
Full textAbstract:
碩士國立清華大學
化學系
103
Abstract This thesis is divided into two sections, the first chapter is copper-catalyzed Povarov reaction between N-alkyl N-methylaniline and saturated heterocyclic ring. The second chapter explores synthesis the novel precursors and then uses atomic layer deposition technology to grow silicon nitride film. Chapter 1 We develop Cu-catalyzed oxidative Povarov reactions between N-alkyl N-methylanilines and saturated oxa- or thiacycles with tert-butyl hydroperoxide (TBHP). Importantly, these reactions do not involve [4π] or [2π] motifs as the initial reagents. The use of cheap alkane-based substances as building units is of mechanistic and practical interest as two inert sp3 C–H bonds are activated. Chapter 2 Given the widespread use of atomic layer deposition reaction, our goal is to generate silicon nitride film by ALD. Therefore, we design the structure of the precursors, and synthesize two novel metal precursor with four identical substituents of silicon. We use simple way to achieve the synthesis. However, limited by equipment incomplete, there is no way to use new precursors with NH3 undergoing atomic layer deposition reaction, so we use H2O to test. But the test result of ALD by using precursor II-1a and H2O is not good. My laboratory colleagues are working on improving the structure of the precursor. Once the equipment complete, we will use our novel precursors with ammonia by ALD processes one by one.
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Chiang, Yen Hsin, and 姜妍忻. "Develop Boron-doped Graphene by Chemical Vapor Deposition and Synthesis of Novel Precursors of Silicon Nitride Film." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/75843415957193300149.
Full textAbstract:
碩士國立清華大學
化學系
104
Chapter I We synthesized boron-contained polyaromatic hydrocarbon ,and it was used to grow boron-doped graphene by chemical vapor deposition, then we got large area and uniform monolayer graphene. We measured and analyzed its physical properties. Boron-doped graphene was patterned and used as anode in a green phosphorescent OLED device that showed an outstanding external quantum efficiency. Chapter II Since electronic devices were miniaturizated, atomic layer deposition (ALD) method for thin film has been focused recently. In this chapter, to produce silicon nitride thin film with using synthesis of novel silicon precursor is our main research goal, by home-made ALD system. Finally, we got the good insulating film.
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Hung-YiTsai and 蔡鴻亦. "The Synthesis of Calcium Silicon-Based (Oxy)nitride Phosphors and the Investigation of Separated-Layer and Remote Configurations of Their Fabricated White Light-Emitting Diodes." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/83545535178551819088.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
101
It was known that the combination of blue light-emitting diodes (LEDs) and the mixture of yellow and red phosphors was an alternative way to fabricate a phosphor-converted white LED (pc-WLED) with the high color rendering index (CRI). In this study, we sought to synthesize CaSi2O2N2:Eu2+ and Ca2Si5N8:Eu2+ phosphors which could be well excited by blue lights by the solid-state reaction under normal atmosphere. The main emission bands of CaSi2O2N2:Eu2+ and Ca2Si5N8:Eu2+ phosphors were located at 560 and 608 nm, respectively. Besides, they also exhibited the good thermal stability with T50 at ＞160℃. The external quantum efficiency of optimized Ca0.63Si2O2N2:0.37Eu2+ and optimized Ca1.97Si5N8:0.03Eu2+ were 30.83% and 24.02% under 450-nm excitation, respectively. Accordingly, both CaSi2O2N2:Eu2+ and Ca2Si5N8:Eu2+ phosphors showed the potential to be applied on the blue LEDs. Furthermore, their excitation spectra in a broad range of 300-520 nm indicated that these phosphors could also be applied on the pc-WLEDs with the near-UV LEDs. The host lattice of CaSi2O2N2:Eu2+ phosphors would expand because of the substitution of Ca2+ by Eu2+ ions, which lead to the change of micro-structure. Therefore, the concentration quenching point could be enhanced, and the emission intensity reached a maximum at 37 mol% where the solid solubility of Eu2+ ions was saturated. With a further increase in the Eu2+ doping level, the crystal structure started to disintegrate and the volume of the unit cell decreased, which caused the supersaturation of Eu2+ concentration; therefore, the concentration quenching occurred and the emission intensity began to decrease. Due to the said variation of the lattice, the CaSi2O2N2 host could allow more amount of Eu2+ doping than that of other oxynitride hosts, indicating the possibility of higher emission intensity. As a result, the external quantum efficiency of the high-doping sample (37 mol%) was 2.47 times than that of the low-doping sample (5 mol%). Such an eye-catching improvement significantly enhanced the feasibility of this phosphor for application to the pc-WLEDs. The pc-WLEDs were fabricated by the blue LED chips, Ca0.63Si2O2N2:0.37Eu2+ and Ca1.97Si5N8:0.03Eu2+ phosphors. The effects of phosphor configurations and the reflective index of remote layers on optical characteristics of pc-WLEDs were investigated. Under 350 mA, the results demonstrated that the luminous efficiency and luminous power of pc-WLEDs utilizing the Y down/ R up type (red phosphor layer was above yellow phosphor layer) phosphor configuration and the step index (step-refractive index) remote configuration were 20% and 21.4% respectively higher than those of pc-WLEDs utilizing the Mixed Type (red and yellow phosphors mixed together) phosphor configuration and the silicone gel as remote layers. The luminous efficiency, luminous power, C.I.E. coordinates, correlated color temperature (CCT), and CRI of the former pc-WLED were 32.58 lm/W, 146.19 mW, (0.3217, 0.2704), 6401 K, and 78, respectively.
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Chen, Wen-ju, and 陳韋儒. "Synthesize Silicon Carbide-Silicon Nitride Composites from Rice Husks by Hydrothermal Method." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/60210356333210450663.
Full textAbstract:
碩士大同大學
材料工程學系(所)
96
The rice husks (RHs) could remove most of impurities and metallic contents by undergoes thermal decomposed under 600oC and 800oC with 3 hours duration, and the residual rice husk ashes (RHAs) contained silicon dioxide (cristobalite phase) as a main phase with trace organic and metallic matters. In this study we used rice husks as raw materials, and added hydrofluoric acid (HF) solution as mineralizer for silica dissolved, ammonium hydroxide (NH4OH) was used as a source of nitrogen gas and partial water vapor pressure. Therefore, we tried to synthesized silicon carbonitride and silicon nitride crystalline by controlled reaction temperature, duration and additives. In the study of [(p-RHA + HF + C + H2O) + NH4OH] parts, that shows the final low quartz phase transformed from cristobalite phase through Reconstructive Phase Transformation (RPT) processes and followed Displacive Phase Transformation (DPT). In the other hand, in the study of [(RHA + HF) + NH4OH (600RHA or 800RHA)] parts, as present, the silicon carbonitride crystallized started at reaction temperature and duration achieved to 250oC with 24 hours, and then the intensity of crystallize increased with reaction temperature and duration increase. However, increased the reaction temperature not only helps crystallized of SiCN but also provided more probability of embedded of oxygen and nitrogen atoms in silicon carbonitride or silicon nitride and resulted in lattice twisted. Consequently, the optimal reaction condition is [(800RHA + HF) + NH4OH] under 300oC for 24 hours.
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"Activation of carbon-carbon and carbon-silicon bonds of nitriles by rhodium porphyrin radical." 2002. http://library.cuhk.edu.hk/record=b5895985.
Full textAbstract:
by Fung Chun-wah.Thesis (M.Phil.)--Chinese University of Hong Kong, 2002.
Includes bibliographical references (leaves 117-119).
Abstracts in English and Chinese.
Table of Contents --- p.i
Acknowledgments --- p.v
Abbreviations --- p.vi
Abstract --- p.vii
Chapter PART I: --- ACTIVATION OF CARBON-CARBON BONDS OF NITRILES BY RHODIUM PORPHYRIN RADICAL
Chapter CHAPTER 1 --- General Introduction --- p.1
Chapter 1.1.1 --- Activation of Carbon-Carbon Bond (CCA) by Transitional Metals --- p.1
Chapter 1.1.1.1 --- Potential Application of C-C Bond Activation --- p.1
Chapter 1.1.1.1.1 --- Cracking --- p.1
Chapter 1.1.1.1.2 --- Depolymerization --- p.2
Chapter 1.1.1.2 --- Thermodynamic and Kinetic Considerations in CCA --- p.3
Chapter 1.1.1.3 --- C-C Bond Activation in Strained System --- p.3
Chapter 1.1.1.4 --- C-C Bond Activation facilitated by Aromatization --- p.7
Chapter 1.1.1.5 --- C-C Bond Activation of Carbonyl Compounds --- p.9
Chapter 1.1.1.6 --- C-C Bond Activation of the Nitriles --- p.13
Chapter 1.1.1.7 --- Selective C-C Bond Activation on a Multimetallic Site --- p.16
Chapter 1.1.1.8 --- Intramolecular sp2 -sp3 C-C Bond Activation in PCP System --- p.17
Chapter 1.1.1.9 --- CCA in N-Heterocyclic Carbene --- p.18
Chapter 1.1.1.10 --- CCA in Pt(0) complexes bearing Chelating P´ةN- and P´ةP- Ligands --- p.19
Chapter 1. 1.1.11 --- CCA of Alkyne via Hydroiminoacylation by Rh(I) Catalyst --- p.20
Chapter I. 1.1.12 --- CCA in Homoallylic Alcohol by β-Allyl Elimination --- p.21
Chapter I. 1.1.13 --- C-C Bond Activation by Metathesis of Alkanes --- p.23
Chapter I.1.2 --- Structural Features of Rhodium Porphyrins --- p.25
Chapter I.1.3 --- Objective of the Work --- p.27
Chapter CHAPTER 2 --- Carbon-Carbon Bond Activation (CCA) of Nitriles by Rhodium Porphyrin Radical --- p.28
Chapter I.2.1 --- Introduction --- p.28
Chapter I.2.1.1 --- CCA of Nitroxides by Rhodium(II) Porphyrin Radical Rh(por) --- p.28
Chapter I.2.2 --- CCA of Nitriles by Rh(tmp) Radical --- p.29
Chapter I.2.2.1 --- Synthesis of Rh(tmp)Me --- p.29
Chapter I.2.2.2 --- Synthesis of Rh(tmp) Radical --- p.30
Chapter I.2.2.3 --- Ligand effect on CCA --- p.31
Chapter I.2.2.3.1 --- Synthesis of Phosphines --- p.31
Chapter I.2.2.3.2 --- Reactions between Rh(tmp) and Phosphines --- p.32
Chapter I.2.2.3.3 --- Synthesis of Alkyl Rh(tmp) --- p.35
Chapter I.2.2.4 --- CCA of Nitriles by Rh(tmp) with PPh3 added --- p.36
Chapter I.2.2.4.1 --- Synthesis of Nitrile --- p.36
Chapter I.2.2.4.2 --- Reactions between Rh(tmp) and Nitriles --- p.37
Chapter I.2.3.4 --- Proposed Mechanism of CCA --- p.44
Chapter CHAPTER 3 --- Experimental Section --- p.46
Conclusion --- p.63
References --- p.64
Chapter PART II --- ACTIVATION OF CARBON-SILICON BONDS OF NITRILES BY RHODIUM PORPHYRIN RADICAL --- p.71
Chapter CHAPTER 1 --- General Introduction --- p.71
Chapter II. 1.1 --- Carbon-Silicon Bond Activation by Transitional Metals --- p.71
Chapter II. 1.1.1 --- Potential Application of C-Si Bond Activation --- p.72
Chapter II.l. l.2 --- C(sp3)-Si Bond Activation --- p.73
Chapter II. 1.1.2.1 --- Intermolecular C(sp3)-Si Bond Activation in Strained System --- p.73
Chapter II. 1.1.2.2 --- Intermolecular C(sp3)-Si Bond Activation in Unstrained System --- p.76
Chapter II. 1.1.3 --- C(sp2)-Si Bond Activation --- p.78
Chapter II. 1.1.3.1 --- Intermolecular C(aryl)-Si Bond Activation --- p.78
Chapter II. 1.1.3.2 --- Intramolecular C(aryl)-Si Bond Activation --- p.84
Chapter II. 1.1.3.3 --- C(vinyl)-Si Bond Activation --- p.87
Chapter II. 1.1.4 --- C(sp)-Si Bond Activation --- p.89
Chapter II. 1.2 --- Objective of the Work --- p.92
Chapter CHAPTER 2 --- Carbon-Silicon Bond Activation (CSA) of Nitriles --- p.93
Chapter II.2.1 --- Introduction --- p.93
Chapter II.2.2 --- Reactions between Rh(tmp) Radical and Silylnitriles --- p.93
Chapter II.2.2.1 --- Investigation the CSA of Trimethylsilylcyanide by Rh(tmp) --- p.93
Chapter II.2.2.1.1 --- Synthesis of Rh(tmp)SiMe3 --- p.93
Chapter II.2.2.1.2 --- Synthesis of Rh(tmp)CN --- p.94
Chapter II.2.2.1.3 --- Reactions between Rh(tmp) and Trimethylsilylcyanide --- p.95
Chapter II.2.2.1.4 --- Ligands effect on CSA of Trimethylsilylcyanide by Rh(tmp) --- p.98
Chapter II.2.2.1.5 --- Temperature effect on CSA --- p.101
Chapter II.2.2.2 --- Reactions between Rh(tmp) and other Silylnitriles --- p.102
Chapter II.2.3 --- Mechanism of CSA of Trimethylsilylcyanide --- p.103
Chapter II.2.3.1 --- Proposed Mechanism of CSA of Trimethylsilylcyanide by Rh(tmp) --- p.104
Chapter II.2.4 --- A Comparison of CSA and CCA of Nitriles --- p.105
Chapter CHAPTER 3 --- Experimental Section --- p.107
Conclusion --- p.116
References --- p.117
List of Spectra --- p.120
Spectra --- p.121
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LO, CHIH-HUI, and 羅智暉. "Synthesis and Characterization of Nitric Oxide-Releasing Silica Nanoparticles by a Polymer-Assisted, One-Pot Method." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/69587231750164234491.
Full textAbstract:
碩士國防醫學院
藥學研究所
105
Nitric oxide (NO) is an endogenous gas molecule in the body, which plays an important role in maintaining physiological homeostasis for cardiovascular, neural and immune systems. Moreover, it has been shown that NO can produce cytotoxic effect against cancer cells and bacteria. Besides, NO can inhibit the resistance of cancer cells to tranditional anti-cancer drugs. Accordingly, NO has the potential to be developed as a new therapeutic entity. However, the free-radical nature of NO renders it very unstable and short-lived in the body. To prolong the residence time of NO, it can be chemically modified as stable prodrugs or NO donors. NO will be released from NO donors by breaking the NO-donating groups, thereby producing therapeutic action. Recently, nano drug delivery systems have become a research focus for NO delivery, because of the advantages of using a nanocarrier to provide sustained NO release and targeted delivery. In the previous studies, our group has developed a simple and convenient method to synthesize and prepare NO-releasing silica nanoparticles (SiNPs), based on S-nitrosation (formation of S-NO bonds) of a mercaptosilane precursor, and using solvent displacement (or nanoprecipitation). The as-prepared SiNPs carry NO with the S-NO linkage and were therefore dubbed as SNO-SiNPs. Although our previous approach is much simpler than the tranditional methods, it still requires reaction in an organic solvent for 24 h before nanoprecipitation. In this present study, the goal is to develop a novel one-step method that will shorten the reaction time, as well as allow synthesis under an environment-friendly condition. The synthesis is performed in a solvent-free aqueous solution containing the silane precursor (3-mercaptopropyl trimethoxysilane, MPTMS), polyvinyl alcohol (PVA), sodium nitrite, and hydrochloric acid in one pot. In the reaction mixture, PVA was added to facilitate the formation of stable SiNPs. Sodium nitrite was acting as a nitrosating agent in the presence of HCl. The result shows that sub-100 nm SiNPs (based on TEM and SEM) can be prepared from the proposed one-step reaction within 2 to 4 h. The experimental conditions and parameters have been systematically studied and optimized, and the resulting particle preparations have been thoroughly characterized using varius measurements, including dynamic light scattering (DLS), TEM, SEM, zeta potential, turbidity, FTIR, MP-AES determination of silicon, solid-state Si NMR, determinations of PVA and NO contents, as well as NO release. Remarkably, the as-prepared SiNPs shows dented or buckled morphology on the surface under the eletron microscopy after drying. The surface buckling resulted in the formation of apple-like, or even donut-like structures. The NO release kinetics for SiNPs prepared via the one-pot PVA route was characterized and the result shows faster NO release compared with SNO-SiNPs prepared from our pevious approach. Cytotoxicity studies show inhibitory effects and weak chemosensitizing effects against breast cancer cell lines. In conclusion, a novel, one-pot, solvent-free approach for rapid synthesis of NO-releasing SiNPs has been developed. The formed NPs have intriguing surface morphology that warrants further studies. Notably, the proposed method is in line with the concept of green chemistry.
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Yang, Jian-jhe, and 楊建哲. "Synthesis and applications of nitroxide radical polymer brushes grafted onto silica nanoparticles and Fe3O4@SiO2 core-shell nanoparticles." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/88968600508672208541.
Full textAbstract:
碩士國立中山大學
化學系研究所
100
Nitroxide radical groups grafted on silica have been synthesized. The catalytic oxidation of alcohols to aldehydes and ketones using the nitroxide radical groups as a catalyst was also investigated. The results of scanning electron microscopy, infrared spectroscopy, and X-ray photoelectron spectroscopy confirmed that the nitroxide radical groups are successfully grafted onto silica. The yield of the catalytic oxidation using the catalysts is higher than 99%. The catalysts are easily recovered. Furthermore, the reused catalysts still keep high performance in the catalytic oxidation.
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Rogler, Daniela. "Entwicklung einer lichtbogengestützten PECVD-Technologie für die Synthese siliziumbasierter Schichtsysteme unter Atmosphärendruck – Untersuchung des diffusionslimitierten Wachstumsregimes." Doctoral thesis, 2011. https://tud.qucosa.de/id/qucosa%3A26167.
Full textAbstract:
Atmosphärendruckplasmen sind aufgrund ihrer vergleichsweise einfachen Anlagentechnik, potentiell geringen Betriebs- und Investitionskosten sowie ihrer Flexibilität bezüglich Substratgröße seit vielen Jahren von großem Interesse. Die Nutzung von Plasmaquellen mit hoher Precursoranregungseffizienz und ausgedehnter Beschichtungszone ist in diesem Zusammenhang besonders vorteilhaft. In der vorliegenden Arbeit wird deshalb erstmals eine neuartige Langlichtbogenplasmaquelle vom Typ LARGE (Long Arc Generator) zur plasmagestützten Synthese von Schichten bei AP (Atmosphärendruck) eingesetzt. Bei der Remoteaktivierung des Precursors erweisen sich insbesondere sauerstoff- sowie stickstoffhaltige Plasmagase als geeignet, um einen signifikanten Anteil der Plasmaenergie in den Remotebereich zu transferieren. Die entwickelte bogenbasierten PECVD (Plasma Enhanced Chemical Vapour Deposition) unter Atmosphärendruckbedingungen ist durch die Erzeugung hochenergetischer Plasmen gekennzeichnet, der Precursor wird stark fragmentiert und ursprüngliche Bindungen des Precursormoleküls werden vollkommen aufgebrochen.
Die Ergebnisse der Gasphasencharakterisierung mittels optischer Emissions- sowie Infrarotspektroskopie lassen beim Prozess der Precursorfragmentierung im Remoteplasma auf eine zentrale Bedeutung metastabiler sowie dissoziierter Spezies schließen. Weiterhin sind hohe Plasmaleistungen, Molekulargasanteile im Plasmagas und große Plasmagasflüsse für eine wirkungsvolle Remoteaktivierung des Precursors von Vorteil. Einen wichtigen Aspekt des Verfahrens stellt darüber hinaus die Möglichkeit der Synthese sauerstofffreier Schichtmaterialien dar. Es konnte gezeigt werden, dass sowohl der genutzte Atmosphärendruckreaktoraufbau mit seinem Gasschleusenkonzept, als auch die Gasreinheit des verwendeten Prozessgases zu keiner nennenswerten Einlagerung von Sauerstoff in die Schicht führt. Die Schichthärte synthetisierter Siliziumnitrid-Schichten lässt sich ohne zusätzliche Substratheizung durch Prozessparameteroptimierung bis auf eine Härte von 17 GPa steigern. Die dynamische Abscheiderate ist mit 39 nm∙mm/s ebenfalls für eine technische Anwendung ausreichend hoch. Eine eingehende Analyse aller Daten legt den Schluss nahe, dass das Schichtwachstum bei der Atmosphärendruck Remote-PECVD häufig kinetisch gehemmt ist und nicht im thermodynamischen Gleichgewicht stattfindet. Der Wachstumsprozess ist in diesem Fall durch das Phänomen des DLG (Diffusion Limited Growth) gekennzeichnet. Homogennukleation bzw. Gasphasennukleation spielt anders als bislang angenommen auch bei Atmosphärendruckbedingungen keine bzw. eine nur untergeordnete Rolle und ist damit nicht limitierend für die erzielbare mechanische und chemische Stabilität der gebildeten Schichten. Mit steigender Diffusionslimitierung des Schichtbildungsvorganges wird eine Zunahme der Schichtrauheit beobachtet, daraus und aus dem Zuwachs an strained sowie dangling Bonds in der Schicht resultiert eine gesteigerte Affinität der synthetisierten Schichten gegenüber Sauerstoff. Als Schlüsselparameter bezüglich Schichtmorphologie sowie Topographie wird der DLG-Quotient angesehen, welcher das Verhältnis aus Oberflächendiffusionskoeffizient und Auftreffrate schichtbildender Spezies auf dem Substrat darstellt. Damit wurden im Rahmen dieser Arbeit die entscheidenden und verfahrenslimitierenden Aspekte identifiziert und die Grundlage für die weitere Optimierung dieses und anderer Remote-AP-PECVD-Verfahren geschaffen. In ähnlicher Weise wie dies auch durch die Bereitstellung einer verbesserten thermischen Aktivierung des Diffusionsprozesses schichtbildender Spezies auf der Substratoberfläche geschieht, lässt sich mit Hilfe eines niedrigen Stickingkoeffizienten eine Diffusionslimitierung des Schichtbildungsvorgangs bei AP-PECVD unterdrücken. In diesem Zusammenhang besitzt insbesondere Ammoniak im Remotegas einen günstigen Einfluss auf die entstehende Schichtmorphologie und Konformalität der Beschichtung.