The global silicon (Si) cycle is of fundamental importance for the global carbon cycle. Diatom growth in the oceans is a major sequestration pathway for carbon on a global scale (often referred to as the biological pump). Patterns of diatoms preserved in marine sediment records can reveal both natural and anthropogenic driven environmental change, which can be used to understand silicon dynamics and climate change. Si isotopes have been shown to have great potential in order to understand the Si cycle by revealing both past and present patterns of dissolved Si (DSi) utilization, primarily when diatoms form their siliceous frustules (noted as biogenic silica, BSi). However, studies using Si isotopes are still scarce and only a few studies exist where stable Si isotopes are used to investigate the biogeochemical Si cycle in aquatic systems. Therefore, this thesis focuses on developing analytical methods for studying BSi and DSi and also provides tools to understand the observed Si isotope distribution, which may help to understand impacts of climate change and human perturbations on marine ecosystems. The Baltic Sea, one of the biggest estuarine systems in the world, was chosen as the study site. BSi samples from a sediment core in Bothnian Bay, the most northern tip of the Baltic Sea, and diatom samples from the Oder River, draining into the southern Baltic Sea were measured and reported in Paper II and III, after establishing a method for Si isotope measurements (Paper I). Si isotope fractionation during diatom production and dissolution was also investigated in a laboratory-controlled experiment (Paper IV) to validate the observations from the field. The major result is that Si isotope signatures in BSi can be used as an historical archive for diatom growth and also related to changes in climate variables. There is isotopic evidence that the Si cycle has been significantly altered in the Baltic Sea catchment by human activities. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>

Two methods for refining metallurgical grade silicon to solar grade silicon have been investigated. The first method involved the reduction of impurities from metallurgical grade silicon by high temperature vacuum refining. The concentrations of analyzed elements were reduced several times. The main steps in the second refining method include alloying with copper, solidification, grinding and heavy media separation. A metallographic study of the Si-Cu alloy showed the presence of only two microconstituents, mainly pure silicon dendrites and the Cu3Si intermetallic. SEM analysis showed a distinct boundary between the silicon and the Cu3Si phases, with a large concentration of microcracks along the boundary, which allowed for efficient separation. After alloying and grinding, a heavy media liquid was used to separate the light silicon phase from the heavier Cu3Si phase. Cu3Si residues together with the remaining impurities were found to be located at the surface of the pure silicon particles, and should be efficiently removed by acid leaching. Thirty elements were analyzed by the Inductively Coupled Plasma Mass Spectrometry (ICP) chemical analysis technique. ICP revealed a several times higher impurity level in the Cu3Si intermetallic than in the pure silicon; furthermore, the amounts of 22 elements in the refined silicon were reduced below the detection limit where the concentrations of 7 elements were below 1ppmw and 6 elements were below 2ppmw. The results showed that the suggested method is efficient in removing impurities from metallurgical grade silicon with great potential for further development.

Two methods for refining metallurgical grade silicon to solar grade silicon have been investigated. The first method involved the reduction of impurities from metallurgical grade silicon by high temperature vacuum refining. The concentrations of analyzed elements were reduced several times. The main steps in the second refining method include alloying with copper, solidification, grinding and heavy media separation. A metallographic study of the Si-Cu alloy showed the presence of only two microconstituents, mainly pure silicon dendrites and the Cu3Si intermetallic. SEM analysis showed a distinct boundary between the silicon and the Cu3Si phases, with a large concentration of microcracks along the boundary, which allowed for efficient separation. After alloying and grinding, a heavy media liquid was used to separate the light silicon phase from the heavier Cu3Si phase. Cu3Si residues together with the remaining impurities were found to be located at the surface of the pure silicon particles, and should be efficiently removed by acid leaching. Thirty elements were analyzed by the Inductively Coupled Plasma Mass Spectrometry (ICP) chemical analysis technique. ICP revealed a several times higher impurity level in the Cu3Si intermetallic than in the pure silicon; furthermore, the amounts of 22 elements in the refined silicon were reduced below the detection limit where the concentrations of 7 elements were below 1ppmw and 6 elements were below 2ppmw. The results showed that the suggested method is efficient in removing impurities from metallurgical grade silicon with great potential for further development.

Since the traditional CRT(Cathode Ray Tube) replaced by FPD(Flat Panel Display), e.g. LCD¡BOLED¡BPDP, FPD industry is regarded as the important one of global industry following Semi-conductor industry. The main stream of Large-Area Displays is TFT-LCD(Thin Film Transistor-Liquid Crystal Display) and it¡¦s applied a-Si:H TFT (the hydrogenated Amorphous Silicon Thin Film Transistor) as pixel-switch device on LCD. In a-Si:H TFT Cell process, the active region material(a-Si:H) with higher Photoconductivity results into higher off-state current under light illumination and that causes color performance discrepancy as incomplete On/Off operation of pixel-switch devices. As long as the introduction of F into a-Si:H modify the density of states in the gap of a-Si:H(:F), that may result the shift of the Fermi level toward the valence band edge and The density-of-states increasing. It¡¦s effective to decrease the photo leakage current. Due to electro-optical properties of liquid crystal(LC), to drive Pixel-switch device in TFT-LCD shall force On/Off voltage to change Twist Angle of LC is corresponding to have Stress on TFT device. According to DC Stress experiment results, it¡¦s found TFT device with SiF4 dopant can reach better reliability. This issue is aimed to research the photo leakage current variation of a-Si:H TFT at low temperature and ON/Off state effect by stress on TFT device.

This diploma thesis presents experimental evidence of a theoretical concept which predicts the self-organization of delta-layers of silicon nanoclusters in the buried oxide of a MOS-like structure. This approach of "bottom-up" structuring might be of eminent importance in view of future semiconductor memory devices. Unconventionally, a 15nm thin SiO2 layer, which is enclosed by a 50nm poly-Si capping layer and the Si substrate, is irradiated with Si+ ions. Ion impact drives the system to a state far from thermodynamic equilibrium, i.e. the local composition of the target is modified to a degree unattainable in common processes. A region of SiOx (x<2) - where x is a function of depth - is formed which is not stable. During annealing, the system relaxes towards equilibrium, i.e. phase separation (via spinodal decomposition and nucleation) sets in. Within a certain time window of annealing, the structure of the system matches with a structure similar to the multidot non-volatile memory device, the principal character of which is a 2D layer of Si nanoclusters of ~3nm in diameter which is embedded in a 3D SiO2 matrix at a distance of ~3nm from the Si substrate. The physical mechanisms of ion mixing of the two Si-SiOx interfaces and subsequent phase separation, which result in the desired sample structure, are elucidated from the viewpoint of computer simulation. In addition, experimental evidence is presented based on various methods, including TEM, RBS, and SIMS. Of particular importance is a novel method of Si nanocluster decoration which applies Ge as contrast enhancing element in TEM studies of tiny Si nanoclusters.

We have developed continuous random network (CRN) model based Metropolis Monte Carlo simulation tools which are capable of predicting the structural properties of amorphous semiconductor and oxide materials as well as their interface. To bolster the reliability of the CRN model, we have developed force fields based on gradient corrected density functional theory (DFT) calculations. Our in-house CRN-MMC tools have been massively parallelized, which allows us to create fairly large model structures within a reasonable computational time. Using the integrated CRN-MMC tools, we have elucidated the complex growth and structure of self-interstitial and vacancy clusters in silicon and the effect of strain on the structure and stability of the defect clusters. Our work for vacancy clusters suggests that small vacancy defects exclusively favor fourfold-coordination thermodynamically with no significant kinetic limitation rather than void-like structure formation, which has widely been adapted to explain the behavior and properties of vacancy defects. Our results also highlight the identification of stable high-symmetry fourfold-coordinated V₁₂ and V₃₂ clusters that could be expected to exist to a large extent in a vacancy rich region although its direct characterization appears impractical at present. Our work for self-interstitial clusters provides the first theoretical support for earlier experiments which suggest a shape transition from compact to elongated structures around n = 10. When the cluster size is smaller than 10, the stable I₄ and I₈ compact clusters are found to inhibit the formation of elongated defects, whereas the newly discovered fourfold-coordinated I₁₂ state is found to serve as an effective nucleation center for large extended defects. Our CRN-MMC approach also enabled us to elucidate the underlying mechanisms of synthesis and manipulation of Si rich insulators as well as the fundamental understanding of the relationship between the atomic structure and properties. We developed a valence force field based on a modified Keating model for the structure and energetics of amorphous Si rich oxide materials. In particular, our work emphasizes the importance of correctly describing the wide Si-O-Si angle distribution. Our work also suggests that the relative rigidity between Si and SiO₂ matrices is critical in determination of the Si/SiO₂ interface structure. The present potential model coupled with the CRN-MMC method can be used to create structural models (free of coordination defects) for complex a-SiO[subscript x]-based materials, which will further allow thorough studies of the properties of these materials. / text

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"El Ser para-otro sartreano" está estructurada en cuatro partes que corresponden a un común denominador: el análisis del Otro. El otro aparece descrito en su génesis, ejemplificado en la creación literaria, en su dimensión marxistas y finalmente en la ética.Que el Otro en la filosofía de Sartre es una evidencia, es innegable. Pero, ¿cómo actúa específicamente? ¿Qué genera?La respuesta a estas dos preguntas es la tesis que se afirma en este trabajo: creemos que el otro en la filosofía sartreana actúa como una permanente dialéctica cosificadora y genera un sin fin de relaciones las cuales precisan de una moral debidamente articulada para hacer posible que esas relaciones sean lo más amigables posible. Es decir, el análisis del Otro nos lleva a la necesidad de crear una moral que satisfaga las necesidades individuales y sociales.Para demostrarlo he seguido el siguiente procedimiento:1. Un análisis ontológico del Otro desde tres perspectivas: la mirada, cómo está anclado y cómo estás descrito.2. Un recorrido metódico por las obras literarias deteniéndome en el Teatro y enfatizando la acción del prójimo como dialéctica cosificadora.3. Una exposición sobre cómo el Otro al abrirse a la exterioridad se relaciona con los Otros. Aquí he tenido en cuenta la aproximación sartreana al marxismo y en consecuencia trato temas como la rareza, la praxis y materialidad. 4. Finalmente, expongo de qué forma la moral es el elemento regulador entre el Otro y Yo, cómo se fundamenta esa moral y pongo de manifiesto la necesidad de un equilibrio entre el Yo y el Otro. Las conclusiones que extraemos son las siguientes:1. El Otro actúa como una permanente dialéctica cosificadora.2. El Otro genera un sin fin de relaciones las cuales precisan de una moral debidamente articulada para hacer posible que esas relaciones sean lo más armoniosas posibles.3. El análisis del Otro nos lleva a la necesidad de crear una moral que satisfaga las relaciones sociales en todas sus vertientes.4. Finalmente, el ser para-otro es el responsable de que esa moral regule las relaciones sociales e individuales.

Les technologies de films minces sur isolant apparaissent comme des solutions fiables pour la nano électronique. Elles permettent de dépasser les limites des technologies sur substrat silicium massif, en autorisant de faibles tensions d’utilisation et un gain en énergie significatif. En effet, les transistors à semi-conducteurs à grille métallique (MOSFET) avec un substrat totalement déplété (FDSOI) conduisent à des courants de fuites faible et améliorent la variabilité ce qui permet de diminuer les tensions d’alimentation en particulier pour les applications SRAM. A partir du nœud 14 nm, les transistors peuvent intégrer un canal SiGe, le diélectrique high-k et la grille métallique. Tous ces nouveaux modules de procédés technologiques rendent l’analyse électrique des transistors MOS ainsi que sa corrélation avec la technologie plus compliquées. Ce travail de thèse propose plusieurs nouvelles méthodologies d’extraction automatique et statistique de paramètres pour les empilements MOS FDSOI avancées. Ces méthodologies sont toutes basées sur des mesures de capacité par rapport à la tension (C-V) rendant compte du couplage capacitif entre grille métallique, canal et substrat face arrière. Avec de telles caractéristiques C-V, des méthodologies fiables sont proposées pour l’épaisseur d’oxyde de grille équivalente (EOT), le travail effectif de la grille métallique FDSOI (WFeff), ainsi que d’autres paramètres comme les épaisseurs du canal (tch) et de l’oxyde enterré (tbox) ainsi que l’affinité électronique efficace (Xeff) du substrat face arrière qui inclut les différents effets électrostatique à l’œuvre dans l’oxyde enterré et à ses interfaces. Ces différentes méthodologies ont été validées par des simulations quantiques. La force de l’analyse expérimentale a été de contrôler la cohérence des extractions obtenues sur tout un ensemble de transistors MOS obtenus à partir de variation sur les différentes briques de base et de contrôler la cohérence des paramètres extraits. / .Thin film technologies appear as reliable solutions for Nano electronics to go beyond bulk silicon technology limits, allowing lower power bias and thus energy harvesting. Indeed, Metal Oxide Semiconductors transistors (MOSFETs) with fully depleted substrate (FDSOI for ’Fully Depleted Silicon On Insulator’) allow low static off-currents and variability improvement that enable the use of power supply biases lower than with bulk silicon, especially for SRAMs. From 14nm nodes, FDSOI generations are including SiGe channel, high-k dielectric and metal gate. All these new process modules required for technology improvement also significantly increase the complexity of the MOS devices electrical analysis and meanwhile its correlation with technology. This PhD study propose different novel methodologies for automatic and statistical parameter extraction of advanced FDSOI MOS gate stack. These methodologies are all based on capacitance versus voltage (C-V) characteristics, obtained for the capacitive coupling between metal gate, channel and back side. With such C-V characteristics, reliable methodologies are proposed, leading to the extractions of the equivalent oxide thicknesses (EOT), the effective work function of the FDSOI metal gate (WFeff), but also other parameters such as channel and buried oxide thicknesses (tch, tbox) and an effective electron affinity of the substrate well (Xeff) that includes all electrostatic effects in the buried oxide and at its interfaces. Moreover, quantum simulations are considered in order to validate the different methodologies. For experimental analysis, the study has considered coherence and complementarity of different test structures as well as the impact of back substrate polarization

Submitted by Andrea Hayashi (deachan@gmail.com) on 2016-06-22T19:16:13Z No. of bitstreams: 1 dissertacao-flavia-milene-ribeiro-da-silva.pdf: 720783 bytes, checksum: 5f78705b52c32b135d4dbc694a90aa78 (MD5) / Approved for entry into archive by Andrea Hayashi (deachan@gmail.com) on 2016-06-23T12:02:14Z (GMT) No. of bitstreams: 1 dissertacao-flavia-milene-ribeiro-da-silva.pdf: 720783 bytes, checksum: 5f78705b52c32b135d4dbc694a90aa78 (MD5) / Made available in DSpace on 2016-06-23T12:02:14Z (GMT). No. of bitstreams: 1 dissertacao-flavia-milene-ribeiro-da-silva.pdf: 720783 bytes, checksum: 5f78705b52c32b135d4dbc694a90aa78 (MD5) Previous issue date: 2014-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Le présent travaille a par but presenter une analyse des concepts des être-Pour-soi et êtrePour-autrui. Aprés ça, nous recherchons quel rôle le être-pour-autrui pourrait avoir dans la constituition du être-pour-soi, c’est-à-dire, comment l’autre est présent dans la subjetivite de l’homme par dedans. Ceux concepts sont des concepts clés dans la oeuvre sartrien L’être et le néant au fur et à la mesure que ceux concepts sont notre conscience, notre subjetivité. Pour elucider ça, on commence notre recherche par le mode de opération de la conscience strictu sensu à partir de la recherche phénoménologique sartreienne présent dans La transcendance de l’Ego, et aprés on essaye suivre la démarche de la pensée sartrienne. / O presente trabalho tem por objetivo apresentar uma análise dos conceitos de ser-Para-si e ser-Para-outro e a possível influência que o para-outro possa exercer na constituição do para-si ou seja, na subjetividade do homem. Esses conceitos são de fundamental importância na obra sartreana o Ser e o Nada, estando presente em toda a obra, isso porque esses conceitos nada mais são do que a nossa consciência, envolvendo a nossa subjetividade. Entretanto, para tentar elucidar o modo de operação da consciência a partir da fenomenologia passaremos pela obra a Transcendência do Ego, assim a visão do pensamento sartreano acerca da consciência torna-se mais completa.