Dissertations / Theses: 'Silicon carbid'

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Skokan, Jan. "Vliv plastifikátoru na technologii zpracování a vlastnosti slinovaného keramického mateiálu na bázi SiC." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231997.

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This master’s thesis deals with an influence of physical properties and machining technology at adjustment to the basic composition granules and production of technical ceramics. Selected series of experiments have been applied to the different phases of production. Composition of the granules vary according to the used plasticizer and ranks to RTP (ready-to-press) materials. The goal of this thesis is recomendation to the production of RTP granules and next experiments.

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Martinelli, Antonio Eduardo. "Diffusion bonding of silicon carbide and silicone nitride to molybdenum." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40191.

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This study focuses on various aspects of solid-state diffusion bonding of two ceramic-metal combinations, namely: silicon carbide-molybdenum (SiC-Mo), and silicon nitride-molybdenum (Si$ rm sb3N sb4$-Mo). Single SiC-Mo and $ rm Si sb3N sb4$-Mo joints were produced using hot-uniaxial pressing. The microstructure of the resulting interfaces were characterized by image analysis, scanning electron microscopy (SEM), electron probe micro-analysis (EPMA), and X-ray diffraction (XRD). The mechanical properties of the joints were investigated using shear strength testing, depth sensing nanoindentation, and neutron diffraction for residual stress measurement.
SiC was solid-state bonded to Mo at temperatures ranging from 1000$ sp circ$C to 1700$ sp circ$C. Diffusion of Si and C into Mo resulted in a reaction layer containing two main phases: $ rm Mo sb5Si sb3$ and Mo$ sb2$C. At temperatures higher than 1400$ sp circ$C diffusion of C into $ rm Mo sb5Si sb3$ stabilized a ternary phase of composition $ rm Mo sb5Si sb3$C. At 1700$ sp circ$C, the formation of MoC$ rm sb{1-x}$ was observed as a consequence of bulk diffusion of C into Mo$ sb2$C. A maximum average shear strength of 50 MPa was obtained for samples hot-pressed at 1400$ sp circ$C for 1 hour. Higher temperatures and longer times contributed to a reduction in the shear strength of the joints, due to the excessive growth of the interfacial reaction layer. $ rm Si sb3N sb4$ was joined to Mo in vacuum and nitrogen, at temperatures between 1000$ sp circ$C and 1800$ sp circ$C, for times varying from 15 minutes to 4 hours. Dissociation of $ rm Si sb3N sb4$ and diffusion of Si into Mo resulted in the formation of a reaction layer consisting, initially, of $ rm Mo sb3$Si. At 1600$ sp circ$C (in vacuum) Mo$ sb3$Si was partially transformed into $ rm Mo sb5Si sb3$ by diffusion of Si into the original silicide, and at higher temperatures, this transformation progressed extensively within the reaction zone. Residual N$ sb2$ gas, which originated from the decomposition of $ rm Si sb3N sb4,$ dissolved in the Mo, however, most of the gas escaped during bonding or remained trapped at the original $ rm Si sb3N sb4$-Mo interface, resulting in the formation of a porous layer. Joining in N$ sb2$ increased the stability of $ rm Si sb3N sb4,$ affecting the kinetics of the diffusion bonding process. The bonding environment did not affect the composition and morphology of the interfaces for the partial pressures of N$ sb2$ used. A maximum average shear strength of 57 MPa was obtained for samples hot-pressed in vacuum at 1400$ sp circ$C for 1 hour.

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Al-ajrash, Saja M. Nabat. "Processing of Carbon–Silicon Carbide Hybrid Fibers." University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1575987386019875.

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Kortegaard, Nielsen Hanne. "Capacitance transient measurements on point defects in silicon and silicol carbide." Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-211.

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Electrically active point defects in semiconductor materials are important because they strongly affect material properties like effective doping concentration and charge carrier lifetimes. This thesis presents results on point defects introduced by ion implantation in silicon and silicon carbide. The defects have mainly been studied by deep level transient spectroscopy (DLTS) which is a quantitative, electrical characterization method highly suitable for point defect studies. The method is based on measurements of capacitance transients and both standard DLTS and new applications of the technique have been used.

In silicon, a fundamental understanding of diffusion phenomena, like room-temperature migration of point defects and transient enhanced diffusion (TED), is still incomplete. This thesis presents new results which brings this understanding a step closer. In the implantation-based experimental method used to measure point defect migration at room temperature, it has been difficult to separate the effects of defect migration and ion channeling. For various reasons, the effect of channeling has so far been disregarded in this type of experiments. Here, a very simple method to assess the amount of channeling is presented, and it is shown that channeling dominates in our experiments. It is therefore recommended that this simple test for channeling is included in all such experiments. This thesis also contains a detailed experimental study on the defect distributions of vacancy and interstitial related damage in ion implanted silicon. Experiments show that interstitial related damage is positioned deeper (0.4 um or more) than vacancy related damage. A physical model to explain this is presented. This study is important to the future modeling of transient enhanced diffusion.

Furthermore, the point defect evolution in low-fluence implanted 4H-SiC is investigated, and a large number of new defect levels has been observed. Many of these levels change or anneal out at temperatures below 300 C, which is not in accordance with the general belief that point defect diffusion in SiC requires high temperatures. This thesis also includes an extensive study on a metastable defect which we have observed for the first time and labeled the M-center. The defect is characterized with respect to DLTS signatures, reconfiguration barriers, kinetics and temperature interval for annealing, carrier capture cross sections, and charge state identification. A detailed configuration diagram for the M-center is presented.

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Li, Tianbo. "Characteristics of Graphite Films on Silicon- and Carbon-Terminated Faces of Silicon Carbide." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14024.

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Ultrathin graphite films, with thickness from 1-30 atomic layers, are grown on the Si-terminated and C-terminated faces of 6H-SiC and 4H-SiC via thermal desorption of silicon in an ultrahigh vacuum (UHV) chamber or in a high-vacuum RF furnace. Graphite LEED patterns and atom-resolved STM images on graphite films prove that epitaxial growth is achieved on both faces of the SiC substrate. The thickness of graphite films is estimated with modeling the Si:C Auger peak intensities. Through LEED and STM investigations of monolayer graphite grown on the Si-face of SiC(0001) surface, we show the existence of a SiC 6R3*6R3 reconstructed layer between graphite films and the SiC substrate. The complicated LEED patterns can be interpreted partially by the kinematic scattering of the interfacial layer and the 6*6 surface corrugation. Further scanning tunneling spectroscopy (STS) measurements indicate that the graphite films remain continuous over the steps between domains. Carbon nanotubes and carbon nanocaps cover about 40% of the graphitized C-face of SiC. The remaining areas are flat graphite films. Graphite ribbons were made through E-beam lithography. After the lithography process, the graphitic features remain on flat region underneath HSQ residues.

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Ahmed, Asher Shafiq. "Characterisation of a silicon carbide coated low density carbon-carbon composite." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501192.

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Wu, Jiali. "Fabrication and characterisation ceramic matrix continuous fibre reinforced composites by sol-gel processing." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387765.

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Colston, Gerard B. "Wafer scale heteroepitaxy of silicon carbon and silicon carbide thin films and their material properties." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/103470/.

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For years now, many have believed the solution to reducing the cost of the wide bandgap compound semiconductor silicon carbide (SiC) is to grow its cubic form (3C-SiC) heteroepitaxially on silicon (Si). This has the potential to reduce cost, increase wafer size and integrate SiC with Si technology. After decades of research, 3C-SiC grown on Si is still yet to penetrate the commercial market as the process is plagued with various issues such as very high growth temperatures, thermal stresses, high cost, poor epitaxial material quality and poor scalability to wafer sizes beyond 100 mm diameter. The first section of this thesis starts with a focus on the traditional, high temperature growth of 3C-SiC carried out in the first industrial type SiC based reduced pressure chemical vapour deposition (RP-CVD) reactor installed in a UK University. After the process demonstrated little promise for mass scale implementation into the semiconductor industry, a radical change in strategy was made. The research pivoted away from SiC and instead focussed on silicon carbon alloys (Si1-yCy) with carbon (C) contents in the range of 1-3%. Si1-yCy has a range of applications in strain engineering and reducing contact resistance, differing from 3C- SiC quite significantly. Crystalline alloys with C contents around 1.5% were achieved using an industry standard Si based RP-CVD growth system. Analysis was carried out on the defects that form due to the saturation of C in higher content alloys. The high temperature annealing of Si1-yCy resulted in out diffusion of C and traces of 3C-SiC growth which presented itself as a potential buffer layer for 3C-SiC epitaxy. Through the careful selection of growth precursors and process optimisation, high crystalline quality 3C-SiC was grown heteroepitaxially on Si within the industry standard Si based RP-CVD and in-depth material characterisation has been carried out using a vast range of techniques. High levels of electrically active dopants were incorporated into the 3C-SiC and its electrical properties were investigated. Various investigations were carried out on suspended 3C-SiC and Si1-yCy films including strain and tilt measurements through micro X-ray diffraction and the effect of thickness and doping on their optical properties. The results led to a greater understanding of suspended films and provide a foundation for a number of applications in microelectromechanical systems (MEMS) and optical devices. Further material growth research was carried out on Si1-yCy multilayers, selective epitaxy of 3C-SiC and the growth of 3C-SiC on suspended growth platforms. Each topic presents an interesting area for further research. The research presented demonstrates new, state of the art 3C-SiC heteroepitaxial material and its basic structural, electrical and optical properties. A new low-cost and scalable process has been developed for the heteroepitaxial growth of 3C-SiC on Si substrates up to 100 mm with a clear path to scaling the technology up to 200 mm and beyond. Not only does the developed technology have a high commercial impact, it also paves the way for many interesting future research topics, some of which have been briefly investigated as part of this work.

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ABEL, JOAO L. "Obtencao do carboneto de silicio pela reducao carbotermica da silica." reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9443.

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Kausar, Rehana. "Surface studies of silicon carbide deposition on carbon and tungsten substrates." Thesis, University of Salford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314000.

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Penugonda, Madhusudhan R. "Alumina - silicon carbide composites from kaolinite-carbon precursors by hot-pressing." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/28509.

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The system kaolinite - carbon black consisting of cheap precursors has been investigated, in terms of its potential to form A1₂ O₃ - SiC composites. The carbothermal reduction process of mullite and silica was studied, in detail, in the range 1275° to 1810° C and over different periods, both under sintering as well as hot-pressing conditions. It was established that the reduction of mullite and silica starts around 1450° C, where the rate of reaction is very slow. Until about 1800° C during the reduction of mullite, SiO₂ gets preferentially reduced, thus forming a composite ceramic consisting of SiC and A1₂ O₃ phases. The kinetics of the formation of SiC + A1₂ O₃ were followed in the range 1590° - 1660° C and it was noted that under hot-pressing conditions they follow a contracting cylinder model. The rate of reaction increased with the increase in temperature and followed a parabolic path with time because of the geometry of the hot-pressed specimens at each temperature. This indicated that the gas diffusion in and out of the system along the edges of the cylindrical specimens is the rate controlling step. The activation energy of the reduction process was calculated to be 922 KJ/mole. The application of pressure prior to the carbothermal reduction process seemed to be not favourable for the formation of SiC and A1₂ O₃, however, when applied after the beginning of soaking period, this greatly improved the densities and formation of SiC and A1₂ O₃. The microstructure of the samples was analysed using SEM and TEM. It was found that the grain size of the composite ceramic was of the order of 0.2μm. SiC was present mainly in the form of fine platelets. Finally, the isothermal compaction behaviour of the system was studied under a constant pressure in the temperature range 1200° C - 1800° C, during which the formation and carbothermal reduction of mullite and silica took place. A mathematical model based on the least squares fitting was used to fit the compaction curves. Due to the complex nature of the compaction data an empirical approach was used to interpret the data and a viscoelastic model was developed. It was found that the interactive-double-Kelvin unit having two elastic and two viscous components explained the type of compaction behaviour observed in the kaolinite + C system. One of the viscous components (η₁) and one of the elastic components (M₁) were found to be temperature sensitive. It is concluded that starting from the cheap precursors (kaolinite and carbon black) a particulate composite of A1₂ O₃,-SiC can be produced by hot-pressing technique. SiC-whisker formation is not encountered in this system. The very fine grain size of the paniculate composite, resulting in a small flaw size, should provide the composite ceramic with good mechanical properties.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate

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Pellegrino, Paolo. "Point Defects in Silicon and Silicon-Carbide." Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3133.

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Razzell, Anthony Gordon. "Silicon carbide fibre silicon nitride matrix composites." Thesis, University of Warwick, 1992. http://wrap.warwick.ac.uk/110559/.

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Silicon carbide fibre/silicon nitride matrix composites have been fabricated using the reaction bonded silicon nitride (RBSN) and sintered reaction bonded silicon nitride (SRBSN) processing routes. A filament winding and tape casting system was developed to produce sheets of parallel aligned fibres within a layer of green matrix ('prepreg') which were cut, stacked and hot pressed to form a plate. This was nitrided and (in the case of SRBSN matrix composites) hot pressed at 1700°C to density the matrix. The magnesia (MgO) and the yttria/alumina (Y2O3/AI2O3) additive SRBSN systems were investigated as matrices for ease of processing and compatibility with the matrix. The MgO additive Si3N4 matrix reacted with the outer carbon rich layer on the surface of the fibres, framing a reaction layer approx. 2pm in thickness. A reaction layer was also observed with the Y2O3/AI2O3 additive matrix, but was thinner (< 0.5um), and was identified as silicon carbide from the electron diffraction pattern. X-ray mapping in the SEM was used to investigate the spatial distribution of elements within the interface region to a resolution < lum, including light elements such as carbon. The 6wt%Y203/ 2wt%Al203 additive SRBSN system was chosen for more detailed investigation, and the majority of characterisation was performed using this composition. Oxidation of composite samples was carried out at temperatures between 1000°C and 1400°C for up to 1000 hours. Little damage was visible after 100 hours for all temperatures, corresponding to a relatively small drop in post oxidation bend strength. After 1000 hours at 1000°C both carbon rich outer layers and the central carbon core of the fibre were removed. Samples were severely oxidised after 1000 hours at 1400°C, having a glass layer on the outer surface and replacement of near surface fibre/matrix interfaces with glass. The post oxidation bend strengths for both conditions were approx.2/3 of the as fabricated strength. Less damage was observed after 1000 hours at 1200°C, and the post oxidation bend strength was higher than the 1000°C and 1400°C samples. Mechanical properties of the SRBSN matrix composite were investigated at room temperature and elevated temperatures (up to 1400°C). The average room temperature values for matrix cracking stress and ultimate strength (in bend) were 651.1 and 713.2 MPa respectively, with corresponding Weibull moduli of 5.7 and 8.7. The stresses are comparable to similar monolithic silicon nitrides. Room temperature tensile matrix cracking and ultimate strength were 232MPa and 413MPa, lower than the bend test results, which were attributed to bending stresses in the sample, lowering the apparent failure stresses. The samples failed in a composite like manner (i.e. controlled rather than catastrophic failure), with a substantially higher woric of fracture than monolithic materials. The average matrix cracking and ultimate bend strength at 1200°C were 516MPa and 554MPa, dropping to 178MPa and 486MPa at 1400°C (the matrix cracking stress was indistinct at 1400°C due to plasticity). The creep and stress rupture properties at 1300°C were investigated in four point bend, using dead-weight loading. The creep rate was KH/s at a stress of 200MPa, lower than a hot pressed silicon nitride with MgO additive, and higher than a hot isostatically pressed Y2O2/SÍO2 additive silicon nitride. A cavitation creep mechanism was deduced from the stress exponent, which was >1. Failure by stress rupture did not have a lower limit, which is also associated with cavitation of the amorphous grain boundary phase.

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Leatherbarrow, Andrew. "Development of carbon fibre reinforced carbon-silicon carbide composites for advanced friction brake applications." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8403.

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In the present study, different origins of recycled carbon fibre and carbon are evaluated against virgin-based alternatives as cost-effective constituents inside carbon fibre/carbon-silicon carbide (Cf/C-SiC) composites. These include: recycled, end-of-life or reclaimed carbon fibre and pyrolytic carbon (pyC), which are investigated inside these composites for potential friction materials to replace or extend the life of current high-end automotive, industrial and aircraft brake discs. The literature review begins by investigating the differences and implications of the applications on the requirements of the carbon fibre inside the composite and documents past and current progress made. The constituents that comprise these composites were investigated and the manufacture routes were reported in terms of their advantages and disadvantages. A three-step process was identified as the most costeffective and promising route to manufacture these new Cf/C-SiC composites with suitably high mechanical properties: 1). Polymer infiltration (PI) and hot pressing (HP) to create a carbon fibre reinforced plastic (CFRP), 2). Pyrolysis to convert the CFRP into a porous Cf/C composite, 3). Liquid silicon infiltration (LSI) to introduce the silicon carbide (SiC) matrix. Beyond this, the aims, feasibility and current progress of recycling carbon fibres were documented. It was found that current recycling technologies are in their infancy, in both academia and industry, although great commercial potential is recognised. Investigations herein revealed the capability to mechanically recycle carbon fibres from waste carbon fibre pre-pregs and CFRP spars, re-use end-of-life carbon fibre pre-pregs and reclaim carbon fibre from existing CFRP spars using pyrolysis. Testing and analysis were split into two stages: firstly, how the pre-preg architecture changes during pyrolysis and secondly, the resulting Cf/C-SiC composites: microstructural evolution after LSI; physical, mechanical and micro-mechanical properties; frictional performance. Pyrolysis of end-of-life pre-pregs revealed no significant difference in comparison to virgin carbon fibre pre-pregs. Instead, any differences were attributed to the: fibre orientation, preform architecture and resin carbon yield. Testing revealed that end-of-life pre-pregs and reclaimed CFRP's were suitable for pyrolysis and further processing toward Cf/C-SiC composites. In addition, the architecture could be either customised or inherited from the original. Physical and mechanical property testing revealed that Cf/C-SiC composites incorporating recycled, end-of-life and re-claimed carbon fibre could achieve comparable densities, open porosities and flexural strengths compared to similarly processed virgin Cf/C-SiC composites. Microstructural examination by optical and electron microscopy revealed that the hierarchy order of the developed microstructure inside these composites by LSI was the same irrespective of the carbon fibre or carbon format. Combined TEM and XRD investigations indicated that the generated SiC and silicon belonged to the same polytypes regardless of the carbon format and that the most likely type was facecentered cubic (FCC) β 3C-SiC and cubic silicon respectively. Small-scale dyno in a disc-on-pad configuration revealed that a Cf/C-SiC composite comprising end-of-life fibre could achieve the required mechanical strength to perform dyno testing and that the surface topography had a significant influence on the coefficient of friction (COF), COF stability and wear rate.

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Beadle, Kendra A. "Chemical vapor deposition of tungsten carbide films on silicon and carbon substrates." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 55 p, 2007. http://proquest.umi.com/pqdweb?did=1338918711&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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Hun, Nicolas. "Mécanismes et cinétiques d'oxydation du SiC à hautes températures et faibles pressions d'oxygène : application au gainage des réacteurs rapides à gaz." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14453/document.

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Les réacteurs rapides à gaz font partie des différents concepts étudiés pour la production d’énergie nucléaire. Les composites SiC/SiC sont des matériaux particulièrement intéressant pour le gainage du combustible, grâce entre autres à leur résistance à la corrosion à haute température.Les mécanismes et les cinétiques d’oxydation du carbure de silicium dans les conditions normales de fonctionnement doivent être identifiés et quantifiés, dans la mesure où la corrosion peut dégrader les propriétés mécaniques du composite. Un système expérimental a été développé pour étudier l’oxydation du SiC à hautes températures et faibles pressions partielles d’oxygène. Il apparaît que dans de telles conditions expérimentales, des mécanismes de réaction interfaciale et de volatilisation viennent s’ajouter à l’oxydation parabolique. Les cinétiques de chaque mécanisme sont déterminées en fonction de la température et de la pression partielle en O2, et sont ensuite utilisées dans un modèle numérique de l’oxydation des composites. Le modèle est utilisé pour prédire la durée de vie du composite dans les conditions normales de fonctionnement d’un réacteur
Gas Fast Reactor (GFR) is one of the different Generation IV concepts under investigation for energy production. SiC/SiC composites are candidates of primary interest for a GFR fuel cladding use, thanks to good corrosion resistance among other properties. The mechanisms and kinetics of SiC oxidation under operating conditions have to be identified and quantified as the corrosion can decrease the mechanical properties of the composite. An experimental device has been developed to study the oxidation of silicon carbide under high temperature and low oxygen partial pressure. The results pointed out that not only parabolic oxidation, but also interfacial reactions and volatilization occur under such conditions. After determining the kinetics of each mechanism, as functions of oxygen partial pressure and temperature, the data are used for the modeling of the composites oxidation. The model will be used to predict the lifetime of the composite in operating conditions

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Godard, Hilary Tony. "Aspects of the silicon carbide filament - silicon interface /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487322984313654.

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Wang, Jue. "Silicon carbide power devices." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/579.

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Fuentes, Ricardo I. "Sintering of silicon carbide." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/14208.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1986.
Vita.
Includes bibliographical references (leaves 152-159).
by Ricardo I Fuentes.
Ph.D.

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Pehlivanoglu, Ibrahim Engin. "SILICON CARBIDE MEMS OSCILLATOR." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1196372276.

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Anthony, Carl John. "Oxide interface studies on silicon and silicon carbide." Thesis, University of Newcastle Upon Tyne, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424150.

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Wu, Huann-Der. "Vapor synthesis of silicon and silicon carbide powders /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487330761217513.

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Zehnder, Thomas. "Deposition of silicon carbide and amorphous carbon films by pulsed laser deposition /." Bern : [s.n.], 1995. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.

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Munbodh, Kineshma. "Evanescent Microwave Characterization of carbon Nanotube Films Grown on Silicon Carbide Substrate." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1183391551.

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Jablonskytė, Lauryna. "Anglies difuzijos silicyje tyrimas." Bachelor's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140716_105123-64848.

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Difuzija – dažniausiai naudojamas procesas, gaminant elektroninius prietaisus. Anglies difuzija iš epitaksinio sluoksnio kristaliniame silicyje gali būti sukelta keliais būdais. Šiame bakalauro darbe nagrinėjame netiesinę difuziją, kai bandiniai veikiami rentgeno spinduliais. Bandymui buvo naudojamos skirtingo storio Cz-Si plokštelės, padengtos plonu dc = 10 µm anglies epitaksiniu sluoksniu. Bandiniai 1 h buvo švitinami DRON-3M difraktometru skirtingos energijos minkštaisiais rentgeno spinduliais. Vario anodo įtampos atitinkamai kiekvienai plokštelei buvo parinktos 10 kV, 20 kV ir 30 kV, o srovės stipris visais atvejais - 20 mA. Šio darbo tikslas - ištirti anglies atomų difuzijos iš epitaksinio sluoksnio į silicį priklausomybę nuo rentgeno spindulių energijos. Spinduliuotės sukelti defektai (priemaišinių anglies atomų absorbcija) buvo matuojami Furje interferometru. Eksperimentas buvo vykdomas kambario temperatūroje. Didžiausią anglies atomų difuzijos koeficientą bei įsiskverbimo gylį gavome prie 10 kV. Gautus rezultatus lyginome su termodifuzijos prie 830 C temperatūros eksperimento rezultatais. Rentgeno spinduliais sukeltos difuzijos koeficientas didesnis , o įsiskverbimo gylis - . Baigiamąjį darbą sudaro 36 puslapiai be priedų, 13 paveikslų ir 1 lentelė.
Diffusion - the most commonly used process in the production of electronic devices. Carbon diffusion in crystalline silicon from epitaxial layer can be induced in several ways. This bachelor thesis is dealing non-linear diffusion of the samples affected by X-rays. In this test were used Cz-Si plates of different thickness, coated with a thin dc = 10 µm layer of carbon epitaxial layer. The samples were irradiated for 1 h with DRON-3M diffractometer at different energy of soft X- rays . Cu anode voltage for each plate were different - 10 kV , 20 kV, 30 kV but a current of all cases - 20 mA . The goal of this test - to investigate the diffusion of carbon into the silicon epitaxial layer dependence on X-ray energy. Defects produced by radiation (carbon impurity absorption) were measured with Fourier interferometer. The experiment were made at room temperature. The largest carbon diffusion coefficient and penetration depth we received at 10 kV. The obtained results were compared with results of thermo diffusion at 830 C temperature. X-rays induced diffusion coefficient higher times, and the depth of penetration - times. The final thesis contains 36 pages, not including appendixes, it includes 13 pictures and 1 table.

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Raghavan, Srikanth. "Comparative studies of 6H-SiC surface preparation." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5766.

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Thesis (M.S.)--West Virginia University, 2008.
Title from document title page. Document formatted into pages; contains xii, 56 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 51-53).

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Choudhury, Arnab. "Process development for a silicon carbide micro four-point probe." Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180116/unrestricted/choudhury%5Farnab%5F200312%5Fms.pdf.

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28

Tatli, Zafer. "Silicon nitride and silicon carbide fabrication using coated powders." Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394640.

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29

Toal, Shane J. "Nanocrystalline silicon carbide growth on silicon using ECR-PACVD." Thesis, London South Bank University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434446.

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30

Nichtawitz, Anthony. "Thermal conductivity of reaction-infiltrated silicon-silicon carbide composites." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41399.

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31

Turan, Servet. "Microstructural characterisation of silicon nitride-silicon carbide particulate composites." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627653.

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32

Gao, Wei. "Oxidation of nitride-bonded silicon carbide (NBSC) and hot rod silicon carbide with coatings." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366751.

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33

Chindanon, Kritsa. "Nitrogen doping in low temperature halo-carbon homoepitaxial growth of 4H-silicon carbide." Master's thesis, Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-07102008-045510.

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34

Wang, Yuan. "Friction surface development and its structure on carbon fibre reinforced silicon carbide disc." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/10003.

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Carbon fibre reinforced ceramic composites (Cf/C-SiC) have been explored as lightweight and durable disc in a friction brake. This composite was manufactured through infiltration of liquid silicon into a Cf/C perform. It has heterogeneous microstructure, composed of three key phases, silicon carbide, Cf/C, and un-reacted residual silicon. The development of the transfer layer on the friction surface of Cf/C-SiC was studied through microstructural image registration of the surface after a range of braking stops on a laboratory-scale dynamometer test rig. When an organic pad was used as the counter face brake pad, it was found that a steady transfer layer was developed in silicon regions right after initial stops; in carbon-fibre/carbon (Cf/C) regions and most of the silicon carbide region, the friction surfaces were unsteady and any possible friction transfer layers were hardly built up. Large voids and cracks/crevices likely became pools to quickly and efficiently collect the transferred materials generated by the friction, but the compacts formed inside the pools were susceptible to be stripped off by further braking operation. Three types of friction surfaces were generalized: type I, the friction transfer layer had a steady relationship with the matrix and respectable longevity; type II, the transfer layer had an unstable relationship with the matrix and poor durability; type III, the friction transfer layer had a steady relationship with the matrix but short lifetime. After testing against organic pads under the laboratory scale dynamometer testing condition, the friction surface of each key phase in Cf/C-SiC composites disc was studied by transmission electron microscopy (TEM). It was found that the transfer layer developed on Si consists of fine particles of metal silicides, silicates and minerals. The substrate damage of Si was not observed, while the precipitates having high oxygen content were found in the substrate. Formation of an interfacial bonding between transfer layer and silicon substrate is believed to be the key factor for the formation of a stable transfer layer on Si. However, the interfacial bonding between transferred materials and SiC was not detected. Kinks are common features developed on the friction surface of SiC. The interface between carbon fibre and carbon matrix was experienced mechanical damage, in form of microcracks, and the transferred material was developed in the interface. Instead of transfer layer, a thin amorphous film, produced by friction induced amorphisation of carbon fibre, was developed on top of carbon fibre.

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35

Dusatko, Tomas A. "Silicon carbide RF-MEM resonators." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100250.

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A low-temperature (<300°C) method to fabricate electrostatically actuated microelectromechanical (MEM) clamped-clamped beam resonators has been developed. It utilizes an amorphous silicon carbide (SiC) structural layer and a thin polyimide spacer. The resonator beam is constructed by DC sputtering a tri-layer composite of low-stress SiC and aluminum over the thin polyimide sacrificial layer, and is then released using a microwave O 2 plasma etch. Deposition parameters have been optimized to yield low-stress films (<50MPa), in order to minimize the chance of stress-induced buckling or fracture in both the SiC and aluminum. Characterization of the deposited SiC was performed using several different techniques including scanning electron microscopy, EDX and XRD.
Several different clamped-clamped beam resonator designs were successfully fabricated and tested using a custom built vacuum system, with measured frequencies ranging from 5MHz to 25MHz. A novel thermal tuning method is also demonstrated, using integrated heaters directly on the resonant structure to exploit the temperature dependence of the Young's modulus and thermally induced stresses.

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36

Iwata, Hisaomi. "Stacking faults in silicon carbide /." Linköping : Univ, 2003. http://www.bibl.liu.se/liupubl/disp/disp2003/tek817s.pdf.

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37

Pedersen, Henrik. "Chloride-based Silicon Carbide CVD." Doctoral thesis, Linköpings universitet, Materiefysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15428.

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Silicon carbide (SiC) is a promising material for high power and high frequency devices due to its wide bandgap, high break down field and high thermal conductivity. The most established technique for growth ofepitaxial layers of SiC is chemical vapor deposition (CVD) at around 1550 °C using silane, SiH4, and lighthydrocarbons e g propane, C3H8, or ethylene, C2H4, as precursors heavily diluted in hydrogen. For high-voltagedevices made of SiC thick (> 100 μm), low doped epilayers are needed. Normal growth rate in SiC epitaxy is~ 5 μm/h, rendering long growth times for such SiC device structures. The main problem when trying to achievehigher growth rate by increasing the precursor flows is the formation of aggregates in the gas phase; for SiCCVD these aggregates are mainly silicon droplets and their formation results in saturation of the growth ratesince if the gas flow does not manage to transport these droplets out of the growth zone, they will eventuallycome in contact with the crystal surface and thereby creating very large defects on the epilayer making theepilayer unusable. To overcome this problem, high temperature- as well as low pressure processes have beendeveloped where the droplets are either dissolved by the high temperature or transported out of the susceptor bythe higher gas flow. A different approach is to use chloride-based epitaxy that uses the idea that the silicondroplets can be dissolved by presence of species that bind stronger to silicon than silicon itself. An appropriatecandidate to use is chlorine since it forms strong bonds to silicon and chlorinated compounds of high purity canbe purchased. In this thesis the chloride-based CVD process is studied by using first a single molecule precursor,methyltrichlorosilane (MTS) that contributes with silicon, carbon and chlorine to the process. Growth of SiCepilayers from MTS is explored in Paper 1 where growth rates up to 104 μm/h are reported together withmorphology studies, doping dependence of growth rate and the influence of the C/Si- and Cl/Si-ratios on thegrowth rate and doping. In Paper 2 MTS is used for the growth of 200 μm thick epilayers at a growth rate of 100μm/h, the epilayers are shown to be of very high crystalline quality and the growth process stable. The growthcharacteristics of the chloride-based CVD process, is further studied in Paper 3, where the approach to add HClgas to the standard precursors silane and ethylene is used as well as the MTS approach. A comparison betweenliterature data of growth rates for different approaches is done and it is found that a precursor molecule withdirect Si-Cl bonds should be more efficient for the growth process. Also the process stability and growth ratedependence on C/Si- and Cl/Si are further studied. In Paper 4 the standard growth process for growth on 4° offaxis substrates is improved in order to get better morphology of the epilayers. It is also shown that the optimizedprocess conditions can be transferred to a chloride-based process and a high growth rate of 28 μm/h wasachieved, using the HCl-approach, while keeping the good morphology. In Paper 5 chloride-based CVD growthon on-axis substrates is explored using both the HCl- and MTS-approaches. The incorporation of dopants in SiCepilayers grown by the chloride-based CVD process is studied in Papers 6 and 7 using the HCl-approach. InPaper 6 the incorporation of the donor atoms nitrogen and phosphorus is studied and in Paper 7 theincorporation of the acceptor atoms boron and aluminum. The incorporation of dopants is found to follow thetrends seen in the standard growth process but it is also found that the Cl/Si-ratio can affect the amount ofincorporated dopants.
Kiselkarbid (SiC) är ett fascinerande material som samtidigt är mycket enkelt och mycketkomplicerat. Det är enkelt eftersom det byggs upp av bara två sorters atomer, kisel och kol.Atomerna bygger upp kristallens struktur genom att bilda Si-C bindningar och man kan beskrivakristallstrukturen som uppbyggd av tetraedrar med en kiselatom (eller kolatom) i mitten och enkolatom (eller kiselatom) i varje hörn på tetraedern. Samtidigt är SiC komplicerat eftersomberoende på hur man staplar dessa tetraedrar kan man få olika varianter på kristallstrukturen, såkallade polytyper. Det finns drygt 200 kända polytyper av kiselkarbid, men det är dock bara enhandfull av dessa polytyper som är tekniskt intressanta. Kiselkarbid är intressant eftersom det ärett hårt material som inte heller påverkas nämnvärt av kemiskt aggressiva miljöer ellertemperaturer upp till 2000 °C; dessutom är SiC en halvledare och tack vare dess tålighet är det ettmycket bra material för elektriska komponenter för högspänningselektronik eller för användningi aggressiva miljöer. För att kunna tillverka dessa komponenter måste man kunna odla kristaller av kiselkarbid. Detfinns i princip två typer av kristallodling; i) odling av bulkkristaller, där stora kristaller odlas föratt sedan kan skivas och poleras till kristallskivor (dessa skivor benämns oftast substrat), och ii)odling av epitaxiella skikt, där man odlar ett tunt lager kristall med mycket hög renhet ovanpå ettsubstrat (ordet epitaxi kommer från grekiskans epi = ovanpå och taxis = i ordning, epitaxiellaskikt odlas alltså ovanpå ett substrat och kopierar den kristallina ordningen hos substratet). I detepitaxiella skiktet, eller epilagret som det även kallas, kan man styra den elektriskaledningsförmågan med mycket hög precision genom att blanda in små mängder orenheter iepilagret, man pratar här om att dopa halvledarkristallen. För att odla epilager av SiC använderman CVD, CVD betyder Chemical Vapor Deposition, någon riktigt bra svensk översättningfinns inte men det är en teknik för att framställa ett tunt lager av ett material genom kemiskareaktioner med gaser som startmaterial. I standard CVD-processen för odling av SiC epilager använder man silan (SiH4) som kiselkälla och lätta kolväten som eten (C2H4) eller propan (C3H8) som kolkälla. Dessa gaser späds kraftigtut i vätgas och man odlar epilagret vid ungefär 1500-1600 °C. Med denna process kan man odlaca 5 mikrometer (mikrometer = miljondelsmeter) epilager på en timme. Men för vissakomponenter behöver man ett epilager som är över 100 mikrometer tjockt, vilket görtillverkningen av sådana komponenter både tidsödande och kostsam. Ett problem som manmåste lösa för att få högre tillväxthastighet i processen är att när man ökar mängden silan,kommer kiseldroppar att bildas i gasfasen och om de kommer i kontakt med substratet blirepilagret förstört. I denna avhandling undersöks ett sätt att lösa problemet med kiseldropparnaoch därmed kunna tillåta höga tillväxthastigheter för SiC epilager. Idén är att man kan lösa uppkiseldropparna genom att tillsätta något i gasblandningen som binder starkare till kisel än kisel.En mycket bra atom att använda för detta ändamål är klor eftersom klor binder mycket starkt tillkisel. Man kallar denna process för klorid-baserad CVD. Till att börja med använde vi molekylen metyltriklorsilan (MTS), som innehåller både kol, kiseloch klor, för klorid-baserad tillväxt av SiC epilager. Genom att använda MTS lyckades vi fåtillväxthastigheter mellan 2 och 104 mikrometer i timmen. Vi har även visat att det är möjligtanvända MTS för att odla 200 mikrometer tjocka epilager med en tillväxthastighet på 100mikrometer i timmen utan att den kristallina kvalitén på epilagren försämras. Ett alternativ till attanvända MTS är att addera saltsyra (HCl) i gasform till standard processen. För att förstå denklorid-baserade processen bättre, jämfördes de olika alternativen med litteraturdata från enprocess där man istället för vanlig silan hade använt triklorsilan (TCS) för att få en klorid-baserad process. Det visade sig att MTS- och TCS-processerna krävde mindre kiselhalt i gasfasen för attfå en hög tillväxthastighet, med andra ord var de mer effektiva. Vi förklarade detta med atteftersom dessa startmolekyler har tre kisel-kol bindningar är det enkelt att bilda SiCl2 molekylen,som har visat sig vara ett viktigt mellansteg i den klorid-baserade processen, eftersom man dåbara behöver bryta kemiska bindningar. Om man istället börjar från silan och saltsyra måstekemiska reaktioner ske för att skapa kisel-kol bindningar och därmed SiCl2. När man odlar kristaller underlättar man tillväxten genom att preparera ytan på substratet medatomära steg. Om man tittar på ytan med atomär förstoring kan säga att ytan liknar en trappa,detta är bra eftersom atomerna som bygger upp epilagret gärna fastnar vid atomära steg eftersomde kan binda in till kristallen både neråt och åt sidan. Vi har optimerat standard processen för attfå bättre morfologi, alltså en finare yta, när man odlar på substrat som har mindre andel atomärasteg på ytan och visat att denna optimering går att överföra till en klorid-baserad process medhög tillväxthastighet . Vi har även visat att man kan använda den klorid-baserade processen föratt odla epilager med hög tillväxthastighet på substrat helt utan atomära steg. Slutligen har vi studerat doping av kiselkarbid vid höga tillväxthastigheter med den kloridbaseradeprocessen, både n-typ doping (där man dopar med ämnen som har fler valenselektronerän kol och kisel så att man får ett överskott av elektroner i materialet) med kväve och fosfor, ochp-typ doping (där man dopar med ämnen som har färre valenselektroner än kol och kisel så attman får ett underskott av elektroner i materialet) med bor och aluminium.

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38

Shih, Chienchung James. "Dynamic deformation of silicon carbide /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9824655.

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39

Lee, Te-Hao. "Silicon Carbide High Temperature Logic." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1283437983.

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40

Thomas, Sarah A. "EPR study of intrinsic near surface defects in SiC." Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2009m/thomas.pdf.

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41

Norén, Olof. "Epitaxial and bulk growth of cubic silicon carbide on off-oriented 4H-silicon carbide substrates." Thesis, Linköpings universitet, Halvledarmaterial, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-121637.

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The growth of bulk cubic silicon carbide has for a long time seemed to be something for the future. However, in this thesis the initial steps towards bulk cubic silicon carbide have been taken. The achievement of producing bulk cubic silicon carbide will have a great impact in various fields of science and industry such as for example the fields of semiconductor technology within electronic- and optoelectronic devices and bio-medical applications. The process that has been used to grow the bulk cubic silicon carbide is a modification of the seeded sublimation growth, and the seeds have been grown by sublimation epitaxy. Selected samples have been characterized with a variety of different methods. The surface morphology of the samples has been examined using optical microscope, atomic force microscope and scanning electron microscope. The crystal structure has been investigated by the methods X-ray diffraction and transmission electron microscopy. The electrical resistance of the grown seeds was evaluated by four probe measurements. High crystal quality seeds have been grown with semiconductor properties and bulk silicon carbide was demonstrated using the seeds.

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42

Åberg, Denny. "Capacitance Spectroscopy of Point Defects in Silicon and Silicon Carbide." Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3205.

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43

Whipple, Steven G. "Fabrication and characterization of hybrid silicon-on-silicon carbide wafers." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3219025.

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44

Simner, Steven Philip. "The reaction bonding of silicon carbide using alloyed silicon infiltrants." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670249.

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45

Yang, Nanying. "Characterization and modeling of silicon and silicon carbide power devices." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/29643.

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Power devices play key roles in the power electronics applications. In order for the power electronics designers to fully utilize the performance advantages of power devices, compact power device models are needed in the circuit simulator (Saber, P-spice, etc.). Therefore, it is very important to get accurate device models. However, there are many challenges due to the development of new power devices with new internal structure and new semiconductor materials (SiC, GaN, etc.). In this dissertation, enhanced power diode model is presented with an improvement in the reverse blocking region. In the current power diode model in the Saber circuit simulator, an empirical approach was used to describe the low-bias reverse blocking region by introducing an effect called â conduction loss,â a parameter that causes a linear relationship between the device voltage and current at low bias voltages with no physics meaning. Furthermore, this term is not sufficient to accurately describe the changes to the device characteristics as the junction temperature is varied. In the enhanced model, an analytical temperature dependent model for the reverse blocking characteristics has been developed for Schottky/JBS diodes by including the thermionic-emission mechanism in the low-bias range. The newly derived model equations have been implemented in Saber circuit simulator using MAST language. An automated parameter extraction software package developed for constructing silicon (Si) and silicon carbide (SiC) power diode models, which is called DIode Model Parameter extrACtion Tools (DIMPACT). This software tool extracts the data necessary to establish a library of power diode component models and provides a method for quantitatively comparing between different types of devices and establishing performance metrics for device development. This dissertation also presents a new Saber-compatible approach for modeling the inter-electrode capacitances of the Si CoolMOSTM transistor. This new approach accurately describes all three inter-electrode capacitances (i.e., gate-drain, gate-source, and drain-source capacitances) for the full operating range of the device. The model is derived using the actual charge distribution within the device rather than assuming a lumped charge or one-dimensional charge distribution. The comparison between the simulated data with the measured results validates the accuracy of the new physical model.
Ph. D.

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46

Kim, Hyoun-Ee. "Gaseous corrosion of silicon carbide and silicon nitride in hydrogen /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487327695622538.

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47

Cheng, Zhe. "Reaction Kinetics and Structural Evolution for the Formation of Nanocrystalline Silicon Carbide via Carbothermal Reduction." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5896.

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Nanocrystalline beta-silicon carbide (ß-SiC) was synthesized at relatively low temperature (<1300C) by carbothermal reduction (CTR) reaction in fine scale carbon/silica mixtures. The fine scale mixing of the reactants (i.e., carbon and silica) was achieved by solution-based processing and subsequent heat treatment. The mechanism of the CTR reaction in the current system was investigated from different aspects. The condensates of the volatile species generated during the CTR reaction was collected and analyzed. The results supported previous investigations which suggested that the CTR reaction is a multi-step process that involves silicon monoxide (SiO) vapor as a reaction intermediate. The kinetics of the CTR reaction was investigated by isothermal weight loss study and by the study which determined the amount of SiC formed via quantitative X- ray diffraction (QXRD) analysis. The results of kinetic study were consistent with the "shrinking-core" model, in which the reaction between SiO vapor and carbon at the carbon surface to produce SiC is the rate-controlling step. In addition, several techniques, including XRD, gas adsorption analysis, laser diffraction particle size analysis, SEM, TEM, etc., had been used to study the structural evolutions of the reaction product of CTR. It was demonstrated that the evolutions of product structure characteristics such as crystallite size, specific surface area, specific pore volume, pore size distribution, particle size distribution, and powder morphology, etc. were consistent with each other and provided support to the reaction mechanism proposed.

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48

Legba, Enagnon Thymour. "SYNTHESIS AND CHARACTERIZATION OF a-SILICON CARBIDE NANOSTRUCTURES." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_theses/494.

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Cubic-phase silicon carbide (andamp;acirc;-SiC) nanostructures were successfully synthesized by the reaction of silicon monoxide (SiO) powder with multi-walled carbon nanotubes (MWCNTs) at high temperatures. Experiments were conducted under vacuum or in the presence of argon gas in a high-temperature furnace and the fabrication parameters of temperature (1300 -1500andamp;deg;C), time, and reactant material mass were varied to optimize the material. The resulting samples were then physically characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD analysis revealed the presence of dominant andamp;acirc;-silicon carbide phases. SEM images depicted morphologies similar to the starting MWCNTs, having relatively larger diameter sizes, shorter lengths and reduced curvature. TEM observations showed the presence of solid and hollow nanostructures with both crystalline and amorphous regions. Additional experiments were performed to investigate de-aggregation and dispersion procedures for the andamp;acirc;-SiC nanostructures fabricated. Optimum results for these experiments were achieved by ultrasonication of 0.01 wt.% andamp;acirc;-SiC in N,N dimethyl formamide (DMF) and dispersion using a spin coater. A methodology for electrical testing of andamp;acirc;-SiC nanostructures was developed using the de-aggregation and dispersion process established. SEM observations revealed that the random nature of the dispersion procedure used was not efficient in forming contacts regions that would allow electrical measurements of andamp;acirc;-SiC nanostructures on the pre-patterned silicon substrate.

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49

Kumbhat, Nitesh. "New Carbon-Silicon Carbide Composite Board Material for High Density and High Reliability Packaging." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7100.

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Current board technologies are inherently performance-limited (FR-4) or cost-prohibitive (Al2O3/AlN). Next-generation high-density packaging applications would necessitate a new base substrate material to achieve ultra-fine pitch solder-joint reliability and multiple layers of fine-line wiring at low cost. The NEMI 2000 roadmap defines the need for 4-8 layers of 5-10 m wiring for future system boards. The 2003 ITRS roadmap calls for organic substrates with less than 100-m area-array pitch in the package or board by year 2010. Solder-joint reliability at such fine-pitch is a matter of concern for the industry. Use of underfills reduces thermal stresses but increases cost and, in addition, their dispensing becomes increasingly more complicated with the shorter gaps required for future interconnects. Therefore, there is a pronounced need to evaluate board materials with CTE close to that of Si for reliable flip-chip on board without underfill. Recently, a novel manufacturing process (using polymeric precursor) has been demonstrated to yield boards that have the advantages of organic boards in terms of large-area processability and machinability at potentially low-cost while retaining the high stiffness (~250 GPa) and Si-matched CTE (~2.5 ppm/㩠of ceramics. This work reports the evaluation of novel SiC-based ceramic composite board material for ultra-fine pitch solder-joint reliability without underfill and multilayer support. FE models were generated to model the behavior of flip-chips assembled without underfill and subjected to accelerated thermal cycling. These models were used to calculate solder-joint strains which have a strong direct influence on fatigue life of the solder. Multilayer structures were also simulated for thermal shock testing so as to assess via strains for microvia reliability. Via-pad misregistration was derived from the models and compared for different boards. Experiments were done to assemble flip-chips on boards without underfill followed by thermal shock testing so as to get the number of cycles to failure. To assess microvia reliability, 2 layer structures containing vias of different diameters were fabricated and subjected to thermal cycling. Via-pad misalignment was also studied experimentally. Modeling and experimental results were corroborated so as to evaluate thermomechanical suitability of C-SiC for high-density packaging requirements.

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50

Miller, Bruno 1974. "Hybrid silicon/silicon carbide microstructures and silicon bond strength tests for the MIT Microengine." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9238.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2000.
Also available online at the MIT Theses Online homepage .
Includes bibliographical references (leaves 109-113).
The Gas Turbine Laboratory (GTL) and the Microsystems Technology Laboratory (MTL) at the Massachusetts Institute of Technology initiated a joint effort to develop a series MEMS-based turbine engines and turbo generators in 1995. This thesis focuses on two independent research topics: first, the use of hybrid silicon/silicon carbide structures to extend the operating envelope of the first generation microengine, and second, a testing technique to measure the toughness of silicon to silicon fusion bonds. Due to the relatively low strength of Si at high temperatures, the all-silicon demonstration device does not yet meet the design specifications. The introduction of limited amounts of SiC in the turbine disc and turbine blades can increase the temperature tolerance of the rotating structure by 150-200K. A turbine disc with a 30% SiC core, and hollow turbine blades with a 300pim tall SiC core yield significant improvements in the microengine performance when compared to the all-silicon baseline design: 30% increase in compressor pressure ratio and fourfold increase in shaft power output. However, more aggressive cooling schemes or re-design of the rotating spool is needed for further improvements. Fabrication of the hybrid structures is compatible with the current microengine process flow, although some key SiC process steps must be developed further. A testing technique has been developed to measure the toughness of Si-Si fusion bonds using bi-layer interfacial notched specimens in a four point bend fixture. The test results confirm the trade-off between annealing time and temperature to achieve similar bond strengths. The experimental results agree with theory and published data. Subsequent experiments should further investigate the effect of different annealing time, surface preparation and contacting atmosphere on bond strength. The technique could also be applied to test bond strength between dissimilar materials, for instance silicon and silicon carbide.
by Bruno Miller.
S.M.

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Dissertations / Theses on the topic 'Silicon carbid'

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