Dissertations / Theses: 'Silicon'

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Martinez, Nelson Yohan Reidy Richard F. "Wettability of silicon, silicon dioxide, and organosilicate glass." [Denton, Tex.] : University of North Texas, 2009. http://digital.library.unt.edu/ark:/67531/metadc12161.

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2

Savchyn, Oleksandr. "Silicon-sensitized erbium excitation in silicon-rich silica for integrated photonics." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4642.

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It is widely accepted that the continued increase of processor performance requires at least partial replacement of electronic interconnects with their photonic counterparts. The implementation of optical interconnects requires the realization of a silicon-based light source, which is challenging task due to the low emission efficiency of silicon. One of the main approaches to address this challenge is the use of doping of silicon based matrices with optical centers, including erbium ions. Erbium ions incorporated in various hosts assume the trivalent state (Er[super]3+) and demonstrate a transition at 1.54 micrometer], coinciding with optical transmission windows in both silicon and silica. Due to the low absorption cross-section and discrete energy levels of the Er[super]3+ ion, indirect excitation is necessary. In late 90s it was demonstrated that the incorporation of excess silicon in erbium-doped silica results in strong erbium sensitization, leading to an increase of the effective absorption cross-section by orders of magnitude. The sensitization was considered to occur via silicon nanocrystals that formed at high annealing temperatures. While a large increase of the absorption cross-section was demonstrated, the incorporation of Si nanocrystals was found to result in a low concentration of excited erbium, as well as silicon related free-carrier absorption. The focus of this dissertation is the investigation of the nature of the sensitization mechanism of erbium in silicon-rich silica. The results presented in the dissertation demonstrate that erbium in silicon-rich silica is predominantly excited by silicon-excess-related luminescence centers, as opposed to the commonly considered silicon nanocrystals. This is a remarkable conclusion that changes the view on the exact origin of erbium sensitization, and that resolves several technical challenges that exist for nanocrystal-based sensitization.; The work shows that in order to sensitize erbium ions in silicon-rich silica there is no need for the presence of silicon nanocrystals, and consequently lower fabrication temperatures can be used. More importantly, the results strongly suggest that higher gain values can be acquired in samples annealed at lower temperature (without silicon nanocrystals) as compared to samples annealed at high temperatures (with silicon nanocrystals). In addition, the maximum gain is predicted to be relatively independent of excitation wavelength, significantly relaxing the requirements on the pump source. Based on the experimental results it is predicted that relatively stable performance of erbium-doped silicon-rich silica is possible up to typical processor operating temperatures of ~ 80 - 90[degrees]C making it a viable material for on-chip devices. The results suggest that low temperature annealed erbium-doped silicon-rich silica is a preferable material for on-chip photonic devices as compared with its high temperature annealed counterpart.; The work shows that the density of indirectly excited erbium ions is significantly larger in samples without silicon nanocrystals (annealed at T[less than]1000[degrees]C) as opposed to samples with silicon nanocrystals (annealed at T[greater than]1000[degrees]C). The density of indirectly excited erbium ions, defining the maximum achievable gain, was demonstrated to be approximately excitation wavelength independent, while the effective erbium absorption cross-section was shown to significantly depend on the excitation wavelength. The excitation mechanism of erbium by luminescence centers was shown to be fast (less than] 30 ns) and capable of erbium sensitization to different energy levels. This multilevel nature of erbium excitation was demonstrated to result in two different mechanisms of the excitation of the first excited state of erbium: fast (less than]30 ns) direct excitation by the luminescence centers, and slow (greater than]2.3 microseconds]) excitation due to the relaxation of erbium ions excited into higher energy levels to the first excited state. Based on photoluminescence studies conducted in the temperature range 15-300K it was shown that the relaxation efficiency of erbium from the second excited state to the first excited state (responsible for the slow excitation mechanism) is temperature independent and approaches unity. The relative stability of the optical properties demonstrated in the temperature range 20-200[degrees]C, implies that relatively stable optical gain can be achieved under realistic on-chip operating conditions. The optimum Si excess concentration corresponding to the highest density of sensitized Er[super]3+ ions is shown to be relatively insensitive to the presence of Si nanocrystals and is ~ 14.5 at.% and ~ 11.5 at.% for samples without and with Si nanocrystals respectively. The presented results and conclusions have significant implications for silicon photonics and the industrial application of Er-doped SiO[sub]2. The work shows that in order to sensitize erbium ions in silicon-rich silica there is no need for the presence of silicon nanocrystals, and consequently lower fabrication temperatures can be used. More importantly, the results strongly suggest that higher gain values can be acquired in samples annealed at lower temperature (without silicon nanocrystals) as compared to samples annealed at high temperatures (with silicon nanocrystals). In addition, the maximum gain is predicted to be relatively independent of excitation wavelength, significantly relaxing the requirements on the pump source. Based on the experimental results it is predicted that relatively stable performance of erbium-doped silicon rich silica is possible up to typical processor operating temperatures of ~ 80 - 90[degrees]C making it a viable material for on-chip devices. The results suggest that low temperature annealed erbium doped silicon-rich silica is a preferable material for on-chip photonic devices as compared with its high temperature annealed counterpart.
ID: 029094291; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references.
Ph.D.
Doctorate
Optics and Photonics

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3

WHITLOCK, PATRICK W. "SILICON-BASED MATERIALS IN BIOLOGICAL ENVIRONMENTS." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1116264213.

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4

Martinez, Nelson. "Wettability of Silicon, Silicon Dioxide, and Organosilicate Glass." Thesis, University of North Texas, 2009. https://digital.library.unt.edu/ark:/67531/metadc12161/.

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Wetting of a substance has been widely investigated since it has many applications to many different fields. Wetting principles can be applied to better select cleans for front end of line (FEOL) and back end of line (BEOL) cleaning processes. These principles can also be used to help determine processes that best repel water from a semiconductor device. It is known that the value of the dielectric constant in an insulator increases when water is absorbed. These contact angle experiments will determine which processes can eliminate water absorption. Wetting is measured by the contact angle between a solid and a liquid. It is known that roughness plays a crucial role on the wetting of a substance. Different surface groups also affect the wetting of a surface. In this work, it was investigated how wetting was affected by different solid surfaces with different chemistries and different roughness. Four different materials were used: silicon; thermally grown silicon dioxide on silicon; chemically vapor deposited (CVD) silicon dioxide on silicon made from tetraethyl orthosilicate (TEOS); and organosilicate glass (OSG) on silicon. The contact angle of each of the samples was measured using a goniometer. The roughness of the samples was measured by atomic force microscopy (AFM). The chemistry of each of the samples were characterized by using X-ray photoelectron spectroscopy (XPS) and grazing angle total attenuated total reflection Fourier transform infrared spectroscopy (FTIR/GATR). Also, the contact angle was measured at the micro scale by using an environmental scanning electron microscope (ESEM).

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5

Walters, Robert Joseph Atwater Harry Albert. "Silicon nanocrystals for silicon photonics /." Diss., Pasadena, Calif. : California Institute of Technology, 2007. http://resolver.caltech.edu/CaltechETD:etd-06042007-160130.

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6

Yeh, Jen-Yu. "Electron-beam biased reactive evaporation of silicon, silicon oxides, and silicon nitrides /." Online version of thesis, 1991. http://hdl.handle.net/1850/11106.

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7

Durham, Simon J. P. "Carbothermal reduction of silica to silicon nitride powder." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74221.

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The processing conditions for carbothermal reduction of silica to silicon nitride was found to be sensitive to several key processing parameters: namely the intimacy of mixing of carbon and silica, the temperature, the specific high surface area of carbon, the nitrogen gas purity and the action of the nitrogen gas passing through the reactants.
Sol-gel processing was found to provide superior mixing conditions over dry mixing, which allowed for complete conversion to silicon nitride at optimum carbon:silica ratios of 7:1. The ideal reaction temperature was found to be in the range of 1500$ sp circ$C to 1550$ sp circ$C. Suppression of silicon oxynitride and silicon carbide was achieved by ensuring that: (a) the nitrogen gas was gettered of oxygen, and (b) that the gas passed through the reactants. Thermodynamic modelling of the Si-O-N-C system showed that ordinarily the equilibrium conditions for the formation of silicon nitride are very delicate. Slight deviations away from equilibrium leads to the formation of non-equilibrium species such as silicon carbide caused by the build-up of carbon monoxide. Reaction conditions such as allowing nitrogen gas to pass through the reactants beneficially moves the reaction equilibrium well away from the silicon carbide and silicon oxynitride stability regions.
The particle size of silicon nitride produced from carbon and silica precursors was of the order of 2-3 $ mu$m and could only be reduced to sub-micron range by seeding with ultra-fine silicon nitride. It was shown that the mechanism of nucleation and growth of unseeded reactants was first nucleation on the carbon by the reaction between carbon, SiO gas and nitrogen (gas-solid reaction), and then growth of the particles by the gas phase reaction (CO, SiO, N$ sb2$).

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8

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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9

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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10

Tayarani-Najaran, M. H. "Traps at the silicon/silicon-dioxide heterojunction." Thesis, University of Bradford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278879.

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11

Mehonić, Adnan. "Resistive switching in silicon-rich silicon oxide." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1420436/.

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Over the recent decade, many different concepts of new emerging memories have been proposed. Examples of such include ferroelectric random access memories (FeRAMs), phase-change RAMs (PRAMs), resistive RAMs (RRAMs), magnetic RAMs (MRAMs), nano-crystal floating-gate flash memories, among others. The ultimate goal for any of these memories is to overcome the limitations of dynamic random access memories (DRAM) and flash memories. Non-volatile memories exploiting resistive switching – resistive RAM (RRAM) devices – offer the possibility of low programming energy per bit, rapid switching, and very high levels of integration – potentially in 3D. Resistive switching in a silicon-based material offers a compelling alternative to existing metal oxide-based devices, both in terms of ease of fabrication, but also in enhanced device performance. In this thesis I demonstrate a redox-based resistive switch exploiting the formation of conductive filaments in a bulk silicon-rich silicon oxide. My devices exhibit multi-level switching and analogue modulation of resistance as well as standard two-level switching. I demonstrate different operational modes (bipolar and unipolar switching modes) that make it possible to dynamically adjust device properties, in particular two highly desirable properties: non-linearity and self-rectification. Scanning tunnelling microscopy (STM), atomic force microscopy (AFM), and conductive atomic force microscopy (C-AFM) measurements provide a more detailed insight into both the location and the dimensions of the conductive filaments. I discuss aspects of conduction and switching mechanisms and we propose a physical model of resistive switching. I demonstrate room temperature quantisation of conductance in silicon oxide resistive switches, implying ballistic transport of electrons through a quantum constriction, associated with an individual silicon filament in the SiOx bulk. I develop a stochastic method to simulate microscopic formation and rupture of conductive filaments inside an oxide matrix. I use the model to discuss switching properties – endurance and switching uniformity.

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12

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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13

Loudon, Alison Young. "Investigation of silicon/silicon germanium multiple quantum well layers in silicon avalanche photodiodes." Thesis, Heriot-Watt University, 2002. http://hdl.handle.net/10399/489.

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14

Moskowitz, Steven. "Atomic force miscroscopy [sic] study of SiO₂/Si(111)--(7x7) grown via atomic oxygen plasma /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/11556.

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15

Kah, Masamba. "Comparative study of boron activation in silicon, silicon-on-insulator and silicon-germanium substrates." Thesis, University of Surrey, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540711.

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16

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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17

Griffin, N. "Low-dimensional systems in silicon/silicon-germanium heterostructures." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599710.

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Recent advances in epitaxial growth technology have made the formation of high-quality, strained-layer heterostructures in the silicon-germanium material system possible. This thesis presents an overview of a range of low-temperature measurements of some of these structures. As the materials are relatively new, the processing techniques for making samples are not well-established, so the thesis discusses the methods used, and in particular, it describes a variety of attempts to fabricate gated devices. Transport measurements of a high-mobility two-dimensional hole gas at low temperatures are described and analysed. Effective mass, quantum lifetime and phase-coherence times are extracted, with the temperature-dependence of the latter following a power-law, the exponent of which indicates a relatively clean system. This exponent predicts the scaling exponents around quantum Hall effect to Hall insulator transitions which are also measured. Screening is shown to cause a strong temperature-dependence of the conductivity. Transport measurements of ungated and Schottky-gated samples of high-quality two-dimensional electron gases at low temperatures are also presented. General features are discussed, including a strong overshoot associated with odd-numbered Hall plateaux and an accompanying asymmetry in the valley-spilt Shubnikov-de Haas peaks. A possible explanation in terms of strong inter-valley scattering is put forward. A range of new behaviours is shown to arise when the carrier density is varied by means of a gate. An anomalous quenching of the valley splitting at a filling factor of 3, resistivity fluctuations at high fields and other effects are presented and discussed. Finally, the thesis describes far infrared measurements of a range of electron gas samples. Cyclotron resonance frequencies of ungated samples deviated from the expected proportionality to the magnetic field. This is explained as resulting from a disorder potential coupled with electron-electron interactions, leading to an apparent lateral confinement.

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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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McLaughlin, J. C. "Fracture of silicon wafers and silicon beam transducers." Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384463.

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Stolfi, Michael Anthony. "Optical properties of nanostructured silicon-rich silicon dioxide." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37583.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.
Includes bibliographical references (p. 190-195).
We have conducted a study of the optical properties of sputtered silicon-rich silicon dioxide (SRO) thin films with specific application for the fabrication of erbium-doped waveguide amplifiers and lasers, polarization sensitive devices and devices to modify the polarization state of light. The SRO thin films were prepared through a reactive RF magnetron sputtering from a Si target in an O2/Ar gas mixture. The film stoichiometry was controlled by varying the power applied to the Si target or changing the percentage of 02 in the gas mixture. A deposition model is presented which incorporates the physical and chemical aspects of the sputtering process to predict the film stoichiometry and deposition rate for variable deposition conditions. The as-deposited films are optically anisotropic with a positive birefringence (nTM > nTE) that increases with increasing silicon content for as-deposited films. The dependence of the birefringence on annealing temperature is also influenced by the silicon content. After annealing, samples with high silicon content (>45 at%) showed birefringence enhancement while samples with low silicon content (<45 at%) showed birefringence reduction. A birefringence of more than 3% can be generated in films with high silicon content (50 at% Si) annealed at 11000C.
(cont.) We attribute the birefringence to the columnar film morphology achieved through our sputtering conditions. Er was incorporated through reactive co-sputtering from Er and Si targets in the same O2/Ar atmosphere in order to investigate the energy-transfer process between SRO and Er for low annealing temperatures. By studying the photoluminescence (PL) intensity of Er:SRO samples annealed in a wide range of temperatures, we demonstrated that the Er sensitization efficiency is maximized between 600°C and 700°C. Temperature-resolved PL spectroscopy on SRO and Er:SRO samples has demonstrated the presence of two different emission sensitizers for samples annealed at 6000C and 1 100°C. This comparative study of temperature-resolved PL spectroscopy along with energy Filtered Transmission Electron Microscopy (EFTEM) has confirmed that the more efficient emission sensitization for samples annealed at 6000C occurs through localized centers within the SRO matrix without the nucleation of Si nanocrystals. Er-doped SRO slab waveguides were fabricated to investigate optical gain and loss for samples annealed at low temperatures.
(cont.) Variable stripe length gain measurements show pump dependent waveguide loss saturation due to stimulated emission with a maximum modal gain of 3 ± 1.4 cm-1 without the observation of carrier induced losses. Pump and probe measurements on ridge waveguides also confirms the presence of SRO sensitized signal enhancement for samples annealed at 6000C. Transmission loss measurements demonstrate a significant loss reduction of 1.5 cm-1or samples annealed at 600°C compared to those annealed at 1000°C. These results suggest a possible route for the fabrication of compact, high-gain planar light sources and amplifiers with a low thermal budget for integration with standard Si CMOS processes.
by Michael Anthony Stolfi.
Ph.D.

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21

Yi, Jae Hyung. "Silicon rich nitride for silicon based laser devices." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44315.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.
Page 214 blank.
Includes bibliographical references.
Silicon based light sources, especially laser devices, are the key components required to achieve a complete integrated silicon photonics system. However, the fundamental physical limitation of the silicon material as light emitter and the limited understanding of tli~ excitation mechanism of Er in dielectric media by optical and electrical pumping methods impedes the progress of the research activities in this area. Silicon rich nitride (SRN) has been investigated as a strong candidate for silicon based laser devices. SRN has many advantages over other Si-based materials systems. These advantages include a high electrical injection level at low voltages, a low annealing temperature for Si nanocluster (Si-nc) formation and a large refractive index for strong optical confinement. Strong light emission from localized states in Si-nc embedded in SRN was demonstrated with a PLQE (Photoluminescence Quantum Efficiency) of 7%. This effect was confirmed through several experiments and first principle calculations. Thue Morse aperiodic structures were fabricated with light emitting SRN and SiO2 materials, for the first time. Through the resonance phenomena achieved using this approach an emission enhancement of a factor of 6 was demonstrated experimentally. A sequential annealing technique was investigated to enhance the light emission from the Si-nc based light emitter. Electrical injection was greatly improved with annealing treatments of SRN based devices. In particular, bipolar electrical injection into SRN led to electroluminescence which was comparable to photoluminescence in peak shape and spectral position. Er doped SRN (Er:SRN) was fabricated through a co-sputter technique to achieve light emission at the wavelength of 1.54 [mu]m.
(cont.) Energy transfer from SRN td Er was confirmed and shown to have a strong dependence on Si content. Si racetrack resonator structures with a low loss value of 2.5 dB/cm were fabricated through a Local Oxide (LOCOS) process and coupled with an Er:SRN layer to investigate gain behavior. Electrical injection properties into the Er:SRN layer were investigated and the electroluminescent device was fabricated. A detailed discussion on optical and electrical excitation of Er is provided to clarify the difference of the Er excitation mechanisms. A comparison of key simulation parameters used within the two level equations for optical and electrical excitation of Er atoms is provided to explain how the parameters contribute to each excitation mechanism. The most significant differences between the parameters and excitation mechanisms are also explained. Finally a summary of important factors to achieve a silicon based laser is provided and discussed for future investigation based on the experimental data and the investigation presented in this work.
by Jae Hyung Yi.
Ph.D.

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22

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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23

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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24

Saripalli, Satya. "Transport properties in nanocrystalline silicon and silicon germanium." [Ames, Iowa : Iowa State University], 2008.

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25

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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Wosinski, Lech. "Technology for photonic components in silica/silicon material structure." Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3556.

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The main objectives of this thesis were to develop a lowtemperature PECVD process suitable for optoelectronicintegration, and to optimize silica glass composition forUV-induced modifications of a refractive index in PECVDfabricated planar devices. The most important achievement isthe successful development of a low temperature silicadeposition, which for the first time makes it is possible tofabricate good quality low loss integrated components whilekeeping the temperature below 250oC during the entirefabrication process. Two strong absorption peaks thatappear at1.5 mm communication window due to N-H and Si-H bonds have beencompletely eliminated by process optimization. This openspossibilities for monolithic integration with other,temperature sensitive devices, such as semiconductor lasers anddetectors, or polymer-based structures on the common siliconplatform. PECVD technology for low loss amorphous silicon inapplication to SiO2/Si based photonic crystal structures hasbeen also optimized to remove hydrogen incorporated during thedeposition process, responsible for the porosity of thedeposited material and creation of similar to silica absorptionbands.

Change of the refractive index of germanium doped silicaunder UV irradiation is commonly used for fabrication of UVinduced fiber Bragg gratings. Here we describe our achievementsin fabrication of fiber Bragg gratings and their application todistributed sensor systems. Recently we have built up a laserlab for UV treatment in application to planar technology. Wehave demonstrated the high photosensitivity of PECVD depositedGe-doped glasses (not thermally annealed) even without hydrogenloading, leading to a record transmission suppression of 47dBin a Bragg grating photoinduced in a straight buried channelwaveguide. We have also used a UV induced refractive indexchange to introduce other device modifications or functions,such as phase shift, wavelength trimming and control ofpolarization birefringence.The developed low temperature technology and the UVprocessing form a unique technology platform for development ofnovel integrated functional devices for optical communicationsystems.

A substantial part of the thesis has been devoted tostudying different plasma deposition parameters and theirinfluence on the optical characteristics of fabricatedwaveguides to find the processing window giving the besttrade-off between the deposition rate,chamber temperatureduring the process, optical losses and presence of absorptionbands within the interesting wavelength range. The optimalconditions identified in this study are low pressure (300-400mTorr), high dilution of silane in nitrous oxide and high totalflow (2000 sccm), low frequency (380 KHz) RF source and high RFpower levels (800-1000 W).

The thesis provides better understanding of the plasmareactions during the deposition process. RF Power is the keyparameter for increasing the rate of surface processes so as toaccommodate each atomic layer in the lowest energy statepossible. All the process conditions which favor a moreenergetic ion bombardment (i.e. low pressure, low frequency andhigh power) improve the quality of the material, making it moredense and similar to thermal oxide, but after a certain pointthe positive trend with increasing power saturates. As theenergy of the incoming ion increases, a competing effect setsin at the surface: ion induced damage and resputtering.

Finally, the developed technologies were applied for thefabrication of some test and new concept devices for opticalcommunication systems including multimode interference (MMI)-based couplers/splitters, state-of-the-art arrayed waveguidegrating-based multi/ demultiplexers, the first Bragg gratingassisted MMI-based add-drop multiplexer, as well as moreresearch oriented devices such as a Mach-Zehnder switch basedon silica poling and a Photonic Crystal-based coupler.

Keywords:silica-on-silicon technology, PECVD, plasmadeposition, photonic integrated circuits, planar waveguidedevices, UV Bragg gratings, photosensitivity, arrayed waveguidegratings, multimode interference couplers, add-dropmultiplexers.

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Pettersson, Per-Olov McGill T. C. "Silicon heterojunctions /." Diss., Pasadena, Calif. : California Institute of Technology, 1996. http://resolver.caltech.edu/CaltechETD:etd-09112006-145849.

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Wiszniewski, Witold Roman. "Silicon transducers." Thesis, The University of Sydney, 1994. https://hdl.handle.net/2123/26700.

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The thesis presents a work on micromechanical transducers: infrared detectors and a light modulator; fabricated on a silicon chip using SLMOX (Separation by IMplantation of OXygen) implantation. The devices are built using a double supported beam of typical dimensions: length 100 um; width 7 pm; thickness 0.5 pm and air gap 0.4 um; composed of silicon nitride and SIMOX silicon layers. The high tensile stress of Si3N4 provides stability of the beam. The one-dimensional, analytical analysis of the beam shows that the first resonance frequency and pull-in (collapse) voltage are determined not by a flexural rigidity, but by the tension in the beam. The infrared detectors with a thermocouple, or p—n junction are proposed. The first device consists of p+ SIMOX silicon—platinum thermocouples connected into a thermopile, built in a multibeam structure. The device is a thermal detector, in which a radiant power is transformed to heat by the platinum thin film thermal absorber. Due to the high thermal resistance of the beam, the heat generation increases the beam temperature which is sensed by the thermopile. The analytical model is developed, including the thermal analysis of the illuminated beam and the quantification of the thermoelectric effect. Calculated values of the responsivity, specific detectivity and time constant are in good agreement with experimental values, which for the 20 thermocouple detector are: 3 VW“; 6xl05 cmHz'le"; 4x10'5 sec; respectively. The junction detector consists of one beam with the p-n junction built into it. The device operates as a thermal detector, in which the junction acts like a thermocouple and as a quantum detector, where infrared photons are absorbed directly on post—oxygen implant defects. Due to the complexity of the device, its parameters are not calculated; instead a simplified model is given. The measured parameters at 800 K are: responsivity 2800 VW“; specific detectivity 4x106 cmHsz"; time constant 3.1x104 sec. The last device, the light modulator is a mechanical interferometer, in which electrostatically induced beam deflections changes the reflected light intensity due to variable interference occurring in the air gap. The theoretical analysis of the device includes the analysis of the beam deflection under the electrostatic force and the calculation of the device reflectance. The device shows a depth of modulation of 30% and a fundamental resonant frequency of 2.3 MHZ. All devices were fabricated using purchased SIMOX wafers and standard IC technology.

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Gómez, Martínez Rodrigo. "Intracellular Silicon chips." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/400152.

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Los chips de silicio intracelulares se definen como dispositivos fabricados a partir de las microy nanotecnologías basadas en el silicio y son lo suficientemente pequeños para poder ser introducidos dentro de células vivas, y que podrían ser usados para futuras aplicaciones en ciencias de la vida. Esta tesis se centra en el desarrollo de cuatro desafíos como pruebas de concepto: desde el desarrollo de chips pasivos (micropartículas y códigos de barras) hasta chips como sensores (bioquímicos y de presión). Todos estos prototipos presentan diferentes formas, tamaños y materiales. La optimización de procesos dentro de las micro- y nanotecnologías basadas en el silicio y con técnicas fotolitográficas, permiten la obtención de dispositivos con dimensiones laterales dentro de la micro- y nanoescala, que se internalizan fácilmente en células ya sea para análisis de una única célula o de una población de células. Este trabajo plantea objetivos específicos en los que se describe el diseño, el desarrollo tecnológico, la caracterización y validación biológica de diferentes chips intracelulares. Los primeros dispositivos reportados son chips intracelulares preliminares, y chips como códigos de barras para el marcaje y seguimiento intracelular, siendo dispositivos pasivos, donde se describe su diseño, su desarrollo tecnológico, su caracterización y su validación biológica. Las capacidades tecnológicas de la microfabricación permite la definición de patrones de diseño para obtener un código de barras para aplicaciones a nivel intracelular. Por otra parte, el concepto de funcionalización química se aplica a nuestros chips intracelulares, lo que permite una nueva línea de investigación para reconocimiento bioquímico intracelular. Por último, se consigue diseñar, desarrollar, caracterizar y validar chips intracelulares más funcionales y con mayor número de aplicaciones. Estos chips se diseñan como chips para medidas de presión intracelular dentro de una sola célula, basado en un sistema de medida OptoMecánico. Resumiendo, las amplias capacidades de los chips de silicio intracelulares presentados en el presente trabajo involucran un amplio número de aplicaciones para biología celular, tales como el etiquetado, rastreo celular, y un sofisticado sistema de medida intracelular, tanto químico como físico.
Intracellular silicon chips are defined as devices small enough to be internalized inside single living cells for future applications in life science, where silicon based micro- and nanotechnologies have been used to achieve this purpose. This thesis is focused in the development of four different challenges, from passive chips (microparticles and barcodes) to biochemical and pressure sensors, as a proof of concept. All these prototypes present different shapes, sizes, and materials. Standard photolithographic and silicon-based technologies, which allow the obtaining of devices with lateral dimensions within the micro- and nanoscale to be internalized easily by the cell for single studies or ever by the study of each single cell in a population of cells. This work addresses specific objectives where the design, technological development, characterization and biological validation as intracellular chips inside living cells are described. The first demonstrators show dummy intracellular chips and intracellular barcodes for single cell labeling and tracking, as passive devices, where the design, technological development, characterization and biological validation are described. Technological capabilities of the definition of patterned chips are applied to obtain the intracellular barcodes code design. Furthermore, the chemical functionalization concept is applied to our intracellular devices, enabling a new line of applications for intracellular biochemical recognition. Finally, and going one step forward, and with the main objective of achieving even more functional intracellular chips, the design, technological development, characterization and validation of an intracellular pressure sensor inside a single cell is described. Being this device the first silicon-based NanoOptoMechanical System (NOMS) inside a living cell. Summarizing, the extensive capabilities of the presented intracellular silicon chips imply a broad number of applications in cell biology, such as cell labeling and tracking, and sophisticated intracellular cell sensing.

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Thomas, Mikkel Andrey. "Integrated optical interferometric sensors on silicon and silicon cmos." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26674.

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The main objective of this research is to fabricate and characterize an optically integrated interferometric sensor on standard silicon and silicon CMOS circuitry. An optical sensor system of this nature would provide the high sensitivity and immunity to electromagnetic interference found in interferometric based sensors in a lightweight, compact package capable of being deployed in a multitude of situations inappropriate for standard sensor configurations. There are several challenges involved in implementing this system. These include the development of a suitable optical emitter for the sensor system, the interface between the various optically embedded components, and the compatibility of the Si CMOS with heterogeneous integration techniques. The research reported outlines a process for integrating an integrated sensor on Si CMOS circuitry using CMOS compatible materials, integration techniques, and emitter components.

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Chen, Wan Lam Florence Photovoltaics &amp Renewable Energy Engineering Faculty of Engineering UNSW. "PECVD silicon nitride for n-type silicon solar cells." Publisher:University of New South Wales. Photovoltaics & Renewable Energy Engineering, 2008. http://handle.unsw.edu.au/1959.4/41277.

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The cost of crystalline silicon solar cells must be reduced in order for photovoltaics to be widely accepted as an economically viable means of electricity generation and be used on a larger scale across the world. There are several ways to achieve cost reduction, such as using thinner silicon substrates, lowering the thermal budget of the processes, and improving the efficiency of solar cells. This thesis examines the use of plasma enhanced chemical vapour deposited silicon nitride to address the criteria of cost reduction for n-type crystalline silicon solar cells. It focuses on the surface passivation quality of silicon nitride on n-type silicon, and injection-level dependent lifetime data is used extensively in this thesis to evaluate the surface passivation quality of the silicon nitride films. The thesis covers several aspects, spanning from characterisation and modelling, to process development, to device integration. The thesis begins with a review on the advantages of using n-type silicon for solar cells applications, with some recent efficiency results on n-type silicon solar cells and a review on various interdigitated backside contact structures, and key results of surface passivation for n-type silicon solar cells. It then presents an analysis of the influence of various parasitic effects on lifetime data, highlighting how these parasitic effects could affect the results of experiments that use lifetime data extensively. A plasma enhanced chemical vapour deposition process for depositing silicon nitride films is developed to passivate both diffused and non-diffused surfaces for n-type silicon solar cells application. Photoluminescence imaging, lifetime measurements, and optical microscopy are used to assess the quality of the silicon nitride films. An open circuit voltage of 719 mV is measured on an n-type, 1 Ω.cm, FZ, voltage test structure that has direct passivation by silicon nitride. Dark saturation current densities of 5 to 15 fA/cm2 are achieved on SiN-passivated boron emitters that have sheet resistances ranging from 60 to 240 Ω/□ after thermal annealing. Using the process developed, a more profound study on surface passivation by silicon nitride is conducted, where the relationship between the surface passivation quality and the film composition is investigated. It is demonstrated that the silicon-nitrogen bond density is an important parameter to achieve good surface pas-sivation and thermal stability. With the developed process and deeper understanding on the surface passivation of silicon nitride, attempts of integrating the process into the fab-rication of all-SiN passivated n-type IBC solar cells and laser doped n-type IBC solar cells are presented. Some of the limitations, inter-relationships, requirements, and challenges of novel integration of SiN into these solar cell devices are identified. Finally, a novel metallisation scheme that takes advantages of the different etching and electroless plating properties of different PECVD SiN films is described, and a preliminary evalua-tion is presented. This metallisation scheme increases the metal finger width without increasing the metal contact area with the underlying silicon, and also enables optimal distance between point contacts for point contact solar cells. It is concluded in this thesis that plasma enhanced chemical vapour deposited silicon nitride is well-suited for n-type silicon solar cells.

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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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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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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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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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Lu, Meijun. "Silicon heterojunction solar cell and crystallization of amorphous silicon." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 295 p, 2009. http://proquest.umi.com/pqdweb?did=1654494651&sid=3&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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Sheriff, Bonnie Ann Collier C. Patrick Heath James M. "Silicon nanowires and silicon/molecular interfaces for nanoscale electronics /." Diss., Pasadena, Calif. : California Institute of Technology, 2009. http://resolver.caltech.edu/CaltechETD:etd-06302008-165534.

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Shah, M. "Excitation mechanisms in erbium-doped silicon-rich silicon oxide." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1420212/.

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Since the invention of the first silicon transistor in 1947, the electronics industry has grown at a rapid rate, famously predicted and guided by Moore’s law. However, it has recently become apparent that satisfying Moore’s law is becoming increasingly difficult; we are now approaching the fundamental limits of device miniaturization and device speed, and alternative solutions for this problem are continuously being pursued. Over the past couple of decades, silicon photonics has emerged as a promising alternative solution. By carrying data through photons instead of electrons, many of the problems faced in an electronic device become irrelevant in an equivalent photonic device. The challenge of silicon photonics is to demonstrate lasing in a material that is compatible with existing CMOS processing technology, namely silicon. Light emission from silicon, however, is very inefficient, due to its indirect electronic bandgap. Silicon nanostructures, on the other hand, exhibit far higher light emission efficiencies, which has been attributed to quantum confinement effects. Erbium is one of the most interesting rare earth impurities for optical functionality, as it emits photons at 1.54µm, the wavelength that corresponds to minimum attenuation in silica fibres. However, erbium has a relatively low excitation cross section, and narrow excitation bands, necessitating expensive lasers for amplifier operation. It has been found that, by co-doping erbium with silicon-nanocrystals (Si-ncs), far higher excitation efficiencies of erbium can be attained, along with broadband excitation, through energy transfer from excited Si-ncs. To date, a clear understanding of the physics involved in the excitation mechanism is lacking. In this thesis, I identify erbium excitation processes in the Er doped silicon rich silicon oxide material, through photoluminescence (PL) spectroscopy. In particular, time resolved decay data of erbium emission is analysed through exponential fitting and rate equation modelling. The significance of Purcell enhanced radiative emission, and Er ion-ion interactions are highlighted. Furthermore, a characterisation study of Er doped silicon rich silicon oxide thin films will be carried out, revealing the significance and differences between defect, Si- nanocluster, and Si-nanocrystal sensitisation of Er ions. The prospects of device fabrication will also be discussed.

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Marconi, Alessandro. "Silicon Nanocrystal Based Light Emitting Devices for Silicon Photonics." Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/369171.

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This thesis presents experimental work developing silicon nanocrystal based light emitting devices for silicon photonics. The chapters are organized as follows: In chapter 2, fabrication and characterization of silicon nanocrystal based devices are presented. In collaboration with Intel Corporation and Bruno Kessler Foundation and thanks to the support of European Commission through the project No. ICT-FP7-224312 HELIOS and through the project No. ICT-FP7-248909 LIMA, it is shown that layers and devices containing silicon nanocrystals can be formed in a production silicon-fab on 4 and 8 inch silicon substrates via PECVD and subsequent thermal annealing. Devices produced by single layer and multilayer deposition are studied and compared in terms of structural properties, conduction mechanisms and electroluminescence properties. Power efficiency is evaluated and studied in order to understand the relation between exciton recombination and electrical conduction. A band gap engineering method is proposed in order to better control carrier injection and light emission in order to enhance the electroluminescence power efficiency. In chapter 3, the power efficiency of silicon nanocrystal light-emitting devices is studied in alternating current regime. An experimental method based on impedance spectroscopy is proposed and an electrical model based on the constant phase element (CPE) is derived. It is, then, given a physical interpretation of the electrical model proposed by considering the disordered composition of the active material. The electrical model is further generalized for many kinds of waveforms applied and it is generalized for the direct current regime. At the end, time-resolved electroluminescence and carrier injection in alternate current regime are presented. In chapter 4, erbium implanted silicon rich oxide based devices are presented. The investigation of opto-electrical properties of LED in direct current and alternate current regime are studied in order to understand the injection mechanism and estimate the energy transfer between silicon nanocrystals and erbium. At the end a device layout and process flow for an erbium doped silicon nanocrystal based laser structure are shown. In chapter 5, some other applications of silicon nanocrystal are presented. An example of all-silicon solar cell is shown. The photovoltaic properties and carrier transport of silicon nanocrystal based solar are studied. At the end, the combination of emitting and absorbing properties of silicon nanocrystal based LED are used to develop an all-silicon based optical transceiver.

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Marconi, Alessandro. "Silicon Nanocrystal Based Light Emitting Devices for Silicon Photonics." Doctoral thesis, University of Trento, 2011. http://eprints-phd.biblio.unitn.it/630/1/Tesi_PhD_Marconi_Alessandro.pdf.

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This thesis presents experimental work developing silicon nanocrystal based light emitting devices for silicon photonics. The chapters are organized as follows: In chapter 2, fabrication and characterization of silicon nanocrystal based devices are presented. In collaboration with Intel Corporation and Bruno Kessler Foundation and thanks to the support of European Commission through the project No. ICT-FP7-224312 HELIOS and through the project No. ICT-FP7-248909 LIMA, it is shown that layers and devices containing silicon nanocrystals can be formed in a production silicon-fab on 4 and 8 inch silicon substrates via PECVD and subsequent thermal annealing. Devices produced by single layer and multilayer deposition are studied and compared in terms of structural properties, conduction mechanisms and electroluminescence properties. Power efficiency is evaluated and studied in order to understand the relation between exciton recombination and electrical conduction. A band gap engineering method is proposed in order to better control carrier injection and light emission in order to enhance the electroluminescence power efficiency. In chapter 3, the power efficiency of silicon nanocrystal light-emitting devices is studied in alternating current regime. An experimental method based on impedance spectroscopy is proposed and an electrical model based on the constant phase element (CPE) is derived. It is, then, given a physical interpretation of the electrical model proposed by considering the disordered composition of the active material. The electrical model is further generalized for many kinds of waveforms applied and it is generalized for the direct current regime. At the end, time-resolved electroluminescence and carrier injection in alternate current regime are presented. In chapter 4, erbium implanted silicon rich oxide based devices are presented. The investigation of opto-electrical properties of LED in direct current and alternate current regime are studied in order to understand the injection mechanism and estimate the energy transfer between silicon nanocrystals and erbium. At the end a device layout and process flow for an erbium doped silicon nanocrystal based laser structure are shown. In chapter 5, some other applications of silicon nanocrystal are presented. An example of all-silicon solar cell is shown. The photovoltaic properties and carrier transport of silicon nanocrystal based solar are studied. At the end, the combination of emitting and absorbing properties of silicon nanocrystal based LED are used to develop an all-silicon based optical transceiver.

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Burrows, Michael Z. "Role of silicon hydride bonding environment in alpha-silicon hydrogen films for c-silicon surface passivation /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 152 p, 2008. http://proquest.umi.com/pqdweb?did=1654501711&sid=3&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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Deng, Xin, and 鄧欣. "Positron studies of silicon and germanium nanocrystals embedded in silicon dioxide." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B41508749.

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Deng, Xin. "Positron studies of silicon and germanium nanocrystals embedded in silicon dioxide." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B41508749.

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Kewes, Eloi. "Silicon grinding and fine particles : generation and behavior of metallurgical-grade silicon fine particles during grinding for the silicones industry." Thesis, Ecully, Ecole centrale de Lyon, 2015. http://www.theses.fr/2015ECDL0030/document.

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La poudre de silicium métallurgique (MG-Si, pureté 99 %) ont été étudiées, en se focalisant particulièrement sur les particules fines (taille comprise entre 1 et 10 μm) Ce matériau est utilisé dans l’industrie siliconière pour la synthèse directe du diméthyldichlorosilane et est obtenu par broyage de blocs de silicium. Les propriétés de cette poudre sont cruciales pour le procédé industriel, à la fois en termes de surface spécifique, composition chimique et coulabilité. Comprendre l’influence des particules fines, qui dégradent la coulabilité, et leur origine au cours du broyage est donc d’une importance cruciale. Une nouvelle caractérisation, chimique et cristallographique, des poudres de MG-Si montre que les particules fines sont en moyennes moins chargées en éléments d’alliage que les particules plus grosses. La structure cristalline du silicium est inchangée au cours du broyage, sauf pour les particules superfines (taille inférieure à 1 μm). Celles-ci présentent des zones amorphes : cela montre qu’elles sont soumises à des contraintes plus importantes au cours du broyage, comme cette transformation étant obtenue au-delà d’un seuil de pression. Le comportement du MG-Si en broyage a été étudié pour la première fois. A l’échelle de la particule unique, il est confirmé que les fissures suivent une propagation transgranulaire. De plus, des particules fines peuvent être produites au cours d’un unique événement de broyage, en raison de l’activation simultanée de multiples systèmes de fissures qui peuvent brancher entre elles. La taille critique en-deçà de laquelle la déformation plastique est énergétiquement plus favorable que la propagation de fissure a été estimée à environ 1 μm par une méthode basée sur l’indentation. Ces deux résultats sont cohérents avec la répartition des éléments d’alliages en fonction de la taille de particule. A l’échelle multiparticulaire, une étude pilote en broyeur à tambour tournant a été menée. Les résultats de cette étude ne sont pas disponibles dans cette version publique du manuscrit. Veuillez vous reporter au manuscrit complet. Les conséquences sur la coulabilité de la présence de particules fines dans la poudre de MG-Si produite par broyage ont été caractérisées par mesures d’angle de repos, de dynamique de compaction et en fluidisation. En particulier, un nouveau comportement d’élutriation a été identifié et décrit : l’élutriation séquentielle se produit lorsque des particules fines sont initialement présentes dans le lit fluidisé et se caractérise par l’envolement d’abord des inférieures à environ 30 μm puis seulement des particules de taille supérieure. Ce comportement n’est pas observé en l’absence de fines dans le lit initial. L’explication de ce phénomène pourrait se trouver dans la formation de clusters polydisperses, formés seulement en présence de particules fines. En parallèle de l’élutriation séquentielle, des mesures électrostatiques avec un électromètre externe à la colonne ont montré la présence de potentiels très importants (10 kV), dont le signe correspond à la gamme de taille de particules envolées. Ceci suggère que l’adhésion au sein des clusters pourrait être électrostatique
Metallurgical-grade silicon (MG-Si, 99 %) powders were extensively investigated, particularly focusing on the fine particles (whose size is between 1 and 10 μm) comprised in these powders. This material is a reactant widely used in the silicones industry for the Direct Synthesis and is obtained by size reduction of millimetric silicon lumps. Powder properties are major stakes of the industrial process. Smaller sizes favor high specific surfaces and high rates of production, but can decrease the lowability, thus inducing poor heat evacuation resulting in hot spots and a decrease in selectivity. Such lowability issues are particularly associated with fine particles, hence understand the generation of these particles during grinding is of critical importance. New chemical and crystallographic characterization of MG-Si is presented, showing that fine particles contain on average less alloying elements than larger particles, yet their crystallographic structure is preserved through grinding. On the contrary, superfine particles (smaller than 1 μm) exhibit amorphous zones: this transformation is pressure induced, showing that these particles experience larger stresses during the grinding step. The behavior of MG-Si in grinding mills has been studied for the first time. At the single particle level, it has been confirmed that transgranular fracture is preferred in MG-Si. Moreover, fine particles can be produced from a single fracture event, due to multiple crack propagation and branching. The critical size under which plastic deformation preferentially occurs over fracture has been evaluated to be approximately 1 μm. These two facts are consistent with a lower level of impurities in fines, yet remaining crystalline, and with superfines exhibiting amorphous areas. At the multiple particle level, pilot scale batch milling experiments have been performed. The results are not included in this public version of the manuscript, please refer to the full manuscript. The consequences of the presence of fine particles in ground MG-Si powder on lowability has been assessed by means of angle of repose, compaction tests and fluidization experiments. A new elutriation behavior has been observed and characterized: for naturally ground MS-Si powders (including fine particles), particles smaller than 30 μm are entrained first, then only larger particles. This was not the case in absence of fine particles. The explanation may probably lie within the presence of polydisperse clusters, formed only in presence of fine particles. Parallel to this elutriation behavior, electrostatic measurements with an external electrometer showed that high potential with sign correlated with the type of particle elutriated are attained during elutriation. This may suggest that electrostatics is responsible for cluster formation

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Senior, Laura. "Diatom silicon transporters : from protein function to biomimetic silica synthesis." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.682342.

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Biomineralisation is the synthesis of inorganic materials in biological systems. Many biominerals - such as bone! teeth, and shells - are high-performance composites synthesised with extreme precision under physiological conditions. Understanding biomineralisation is expected to inspire 'green' methods for the manufacture of novel materials. Diatoms are eukaryotic algae that mineralise an external cell wall, or frustule, composed of hydrated silica. Silicification depends upon the uptake of soluble silicon (silicic acid) from the local environment by specific silicic acid transport proteins (SITs). This unusual family of integral membrane proteins are relatively uncharacterised. This project aimed to express and purify 5113 from the diatom Thalassiosira pseudonana (TpSIT3) for further characterisation in vitro, and to explore whether synthetic SIT3 proteoliposomes could be used as a model mineralisation system with potential applications in nanotechnology. TpSIT3 was successfully overexpressed in yeast and purified in the solubilising detergents Fos-choline 12 and octyl glucoside. The purified protein was successfully reconstituted into synthetic liposomes and silicic acid uptake was assessed using two fluorescent assays including a novel method which utilised zinc silicate fluorescence. This method was used to determine that silicic acid transport by TpSIT3 displayed Michaelis-Menten kinetics with a Km of 6.1 ± 2.7 μM, similar to silicic acid uptake studies in diatom cultures. The structure and function of a silicifying cationic peptide were also characterised for the first time. Peptide-mediated silicification only proceeded at ≥2 mM silicic acid when pH was >6.4 and peptide concentration was ≥2.5 mM. These results underpinned efforts to synthesise silica within the int erior lumen of peptide-loaded SIT proteoliposomes. Preliminary electron microscopy and elemental analysis suggested that such an approach was feasible. This thesis thus establishes a series of novel methods that can be used to study silicic acid transport and silica mineralisation in vitro

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46

Pettigrew, Katherine Ann. "Solution synthesis and characterization of silicon and silicon/germanium nanoparticles /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.

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47

Alba, Martín María. "Silicon dioxide microstructures based on macroporous silicon for biomedical applications." Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/285331.

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En aquesta tesi hem desenvolupat materials microestructurats basats en silici macroporós, centrant-nos en la producció de microestructures per la seva aplicació en biomedicina. El silici macroporós es forma per atac electroquímic de silici en electròlits basats en àcid fluorhídric. Es fabriquen mostres de silici macroporós ordenat i aleatori. Amb un procés litogràfic, es pot crear un patró predisenyat en el silici, i així definir els punts de nucleació i aconseguir porus amb un creixement ordenat i un diàmetre uniforme. L’oxidació tèrmica del silici macroporós permet la formació de noves estructures, com micropilars de SiO2. El SiO2 es normalment acceptat com un material biocompatible. Tot i això, utilitzem l’espectroscòpia infraroja per realitzar una caracterització exhaustiva i una modificació adequada de la química de superfície orientada cap a la conjugació de biomolècules. La peculiar arquitectura d’aquests substrats va permetre la creació de partícules multifuncionals amb una doble funcionalització selectiva en les cares interior i exterior. Aquestes microestructures van ser concebudes com a materials per al transport de fàrmacs. Així doncs, aquestes micropartícules de SiO2 van ser proposades com a sistemes d’alliberament de fàrmacs per control de pH quan es combinen amb polielectròlits sensibles al pH. Finalment, la doble funcionalització va ser explotada per crear micropartícules multifuncionals per l’alliberament de fàrmacs dirigida cap a cèl•lules diana. La viabilitat del sistema va ser provada amb cèl•lules cancerígenes in vitro.
En esta tesis hemos desarrollado materiales microestructurados basados en silicio macroporoso, centrándonos en la producción de plataformas y partículas para su aplicación en biomedicina. El silicio macroporoso se forma por ataque electroquímico de silicio en electrolitos basados en ácido fluorhídrico. Se fabricaron muestras de silicio macroporoso ordenado y aleatorio. Con un proceso litográfico, se puede crear un patrón prediseñado en el silicio, y así definir los puntos de nucleación y conseguir poros con un crecimiento ordenado y un diámetro uniforme. La óxidación térmica del silicio macroporoso permite la formación de nuevas estructuras, como micropilares de SiO2. El SiO2 es normalmente aceptado como un material biocompatible. A pesar de esto, utilizamos la espectroscopía infraroja para realizar una caracterización exhaustiva y una modificación adecuada de la química de superficie orientada hacia la conjugación de biomoleculas. La peculiar arquitectura de estos sustratos permitió la creación de partículas multifuncionales con una doble functionalización selectiva en las caras interior y exterior. Estas microestructuras fueron concebidas como materiales para el transporte de fármacos. Así pues, estas micropartículas de SiO2 fueron propuestas como sistemas de liberación de fármacos por control de pH cuando se combinan con polielectrolitos sensibles al pH. Finalmente, la doble funcionalización fue explotada para crear micropartículas multifunctionales para la liberación de fármacos dirigida hacia células diana. La viabilidad del sistema fue probada con células cancerígenas in vitro.
This thesis has explored the fabrication of silicon oxide (SiO2) microstructures based on macroporous silicon (macro-pSi), with a focus on producing suitable platforms and particles for application in biomedicine. Macroporous silicon was formed by the electrochemical etching of low doped p-type silicon in hydrofluoric acid based solutions. Both random and ordered structures were fabricated. A patterning lithography prior etching led to an ordered pore nucleation and consequently tubular structures of uniform size were produced. Thermal oxidation of macro-pSi allowed the formation of novel structures such as SiO2 micropillars, with identical arrangement and dimensions of those in the preceding macro-pSi. SiO2 is generally accepted as a biocompatible material; nevertheless, a methodical study of the surface chemistry and its modification was performed by infrared (IR) spectroscopy to generate surfaces capable of interfacing with living cells. The particular architecture of these substrates allowed creating multifunctional particles with a selective dual functionality in nanometrically separated internal and external sides. We also foresaw these microstuctured materials as drug carriers. Thus, SiO2 microparticles were proposed as pH-controlled drug delivery system when they are combined with pH-responsive polyelectrolytes. Finally, a dual-functionalization of the inner/outer sides was employed for creating multifunctional microparticles, which were demonstrated to be cancer-targeted in in vitro tests.

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48

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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49

Famiyeh, Lord. "Electrodeposition of Silicon in Fluoride Melts : Production of Silicon Films." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16344.

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There has been considerable interest in electrodeposition of silicon from fluoride melts on a suitable substrate for its application in thin film solar cells. The goal of this work is to produce a high purity silicon films from LiF-KF-K2SiF6 (mol %) that could be suitable for solar grade applications, and to study electrodeposition of silicon in the same melt by performing electrochemical measurements. Cyclic voltammetry was carried out both in pure melt LiF-KF and LiF-KF-K2SiF6 (0.13mol/kg) at 750oC on Ag electrode to study the reduction mechanism of fluorosilicate. The reduction mechanism was found to be mass transport diffusion controlled. The diffusion coefficient was estimated to be 1.1x10-5cm2/s from Randles-Sevcik equation.Chronoamperometry was also carried out in LiF-KF-K2SiF6 (0.13mol/kg) at 750oC on Ag electrode at different cathodic potentials and the current-time response, reduction mechanism of silicate ion was studied. It was also found again that the reduction mechanism of fluorosilicate is diffusion controlled. The diffusion coefficient was calculated to be 4.6x10-4cm2/s using the Cottrell equation. The influence of electrolytic parameters such as temperature, concentration of the electroactive species K2SiF6, and current density on the morphology and purity of the deposits and the current efficiency of the electrolytic process was studied. Effect of temperature and concentration was studied on Ag substrate and current density on both Ag and Si substrate. The influence of the substrate (silver and silicon) was also studied. Before the start of each electrodeposition experiment pre-electrolysis was carried out to remove moisture and reduce impurities concentration to ppm level. The deposits obtained were cleaned in ultrasonic bath to get rid of salt inclusions. It was observed that not all the salt inclusions were completely removed and therefore the current efficiency calculated was described to be apparent (not accurate). A few selected deposits were characterized using scanning electron microscope and energy dispersive spectroscopy, the results are shown below. It was observed that at a temperature of 800oC the deposit was dense, coherent, good adhesion to the silver substrate and with less impurities and salt inclusions but at 550oC the deposit was powdered or dendritic with high content of impurities and salt inclusions. At 5mol% of K2SiF6 the deposit consists of homogeneous structure with less impurities and salt but at 20mol% on the microstructure seems to be elongated and contain high content of impurities and salts. On silicon substrate, at current density 101.5mAcm-2 the deposit was dendritic with no grains, weakly adhered to the silicon substrate and also contains more impurities and salts but at 35.5mAcm-2 the deposit contains large grains with columnar microstructure and less impurities and salts. On silver substrate, at 83.8mAcm-2 the deposit consists of fine microstructure with high content of impurities and salts but at 42.9mAcm-2 the deposit consists of bigger and elongated with high porosity and small content of impurities and salts. For the influence of the substrate, it was observed that on sliver the deposit was insoluble with fine microstructure but on silicon it was soluble and weakly adhered with non uniform microstructure which is powdered and dendritic. The deposit obtained on both silver and silicon contains high content of impurities and salts because of the high current density applied (83.8mAcm-2 on Ag and 80.5mAcm-2 on Si).

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50

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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Dissertations / Theses on the topic 'Silicon'

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