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Artykuły w czasopismach na temat "Silicide concentration"
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Pretorius, R., i J. W. Mayer. "Silicide formation by concentration controlled phase selection". Journal of Applied Physics 81, nr 5 (marzec 1997): 2448–50. http://dx.doi.org/10.1063/1.364252.
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De Avillez, R. R., L. A. Clevenger, C. V. Thompson i K. N. Tu. "Quantitative investigation of titanium/amorphous-silicon multilayer thin film reactions". Journal of Materials Research 5, nr 3 (marzec 1990): 593–600. http://dx.doi.org/10.1557/jmr.1990.0593.
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Growth of amorphous-titanium-silicidc and crystalline C49 TiSi2 in titanium/amorphous-silicon multilayer films was investigated using a combination of differential scanning calorimetry (DSC), thin film x-ray diffraction, Auger depth profiling, and cross-sectional transmission electron microscopy. The multilayer films had an atomic concentration ratio of 1Ti to 2Si and a modulation period of 30 nm. In the as-deposited condition, a thin amorphous-titanium-silicide layer was found to exist between the titanium and silicon layers. Heating the multilayer film from room temperature to 700 K caused the release of an exothermic heat over a broad temperature range and an endothermic heat over a narrow range. The exothermic hump was attributed to thickening of the amorphous-titanium silicide layer, and the endothermic step was attributed to the homogenization and/or densification of the amorphous-silicon and amorphous-titanium-silicide layers. An interpretation of previously reported data for growth of amorphous-titanium-silicide indicates an activation energy of 1.0 ± 0.1 eV and a pre-exponential coefficient of 1.9 × 10−7 cm2/s. Annealing at high temperatures caused formation of C49 TiSi2 at the amorphous-titanium-silicide/amorphous-silicon interfaces with an activation energy of 3.1 ± 0.1 eV. This activation energy was attributed to both the nucleation and the early stages of growth of C49 TiSi2. The heat of formation of C49 TiSi2 from a reaction of amorphous-titanium-silicide and crystalline titanium was found to be –25.8 ± 8.8 kJ/mol and the heat of formation of amorphous-titanium-silicide was estimated to be –130.6 kJ/mol.
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HOU, Q. R., Z. M. WANG i Y. J. HE. "THE EFFECT OF OXYGEN ON THE FORMATION OF MANGANESE SILICIDE". Modern Physics Letters B 16, nr 28n29 (20.12.2002): 1135–42. http://dx.doi.org/10.1142/s0217984902004664.
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The behavior of oxygen impurities during thermal annealing of manganese-silicon diffusion couples and reactive deposition of MnSi 1.7 films has been studied. Samples were prepared by reactive deposition or thermal evaporation of manganese on silicon (100) substrates, which were then annealed in vacuum. The investigation techniques included depth profiling using Auger electron spectroscopy and electrical resistance measurements. The oxygen contamination originated from the preparation chamber or exposing the sample to air before thermal annealing. The oxygen diffused into the manganese film and blocked the silicide formation. For reactive deposition of the MnSi 1.7 films, the competition between silicide formation and oxygen diffusion resulted in the formation of silicide films with oxygen concentration of about 5 at% or the diffusion of oxygen in the manganese film with oxygen concentration of about 35 at%. The presence of a higher concentration of oxygen in the manganese layer prevented any silicide formation.
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Nakamura, Kozo, i Junsuke Tomioka. "Effect of Oxygen Precipitates on the Surface-Precipitation of Nickel on Cz-Silicon Wafers". Solid State Phenomena 108-109 (grudzień 2005): 103–8. http://dx.doi.org/10.4028/www.scientific.net/ssp.108-109.103.
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This paper presents a model for the analysis of the surface nucleation and growth of Ni silicide on silicon wafers contaminated by Ni. The model can additionally be used to characterize the gettering reaction of Ni induced by oxygen precipitates. We also discuss the relation between the surface precipitation of Ni silicide and the gettering ability of oxygen precipitate. The surface precipitation of Ni silicide depends on the total surface area of oxide precipitates. When the total surface area of the oxide precipitates exceeds the critical value, the surface precipitation is rapidly suppressed. Our model can explain the phenomenon of the gettering threshold in the following manner. 1) The gettering of Ni by oxygen precipitates is a reaction-limited process at the interface between oxygen precipitate and silicon, as Sueoka proposed. 2) The residual Ni concentration in this reaction-limited gettering process continuously decreases as the total surface area of the oxide precipitates increases. 3) The surface precipitation of Ni silicide is rapidly suppressed when the residual Ni concentration falls below the critical concentration. Our calculation results correspond well with the experimental results.
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Vantomme, A., S. Degroote, J. Dekoster, G. Langouche i R. Pretorius. "Concentration-controlled phase selection of silicide formation during reactive deposition". Applied Physics Letters 74, nr 21 (24.05.1999): 3137–39. http://dx.doi.org/10.1063/1.124090.
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Shenai, Krishna. "Thermal stability of TiSi2 films on single crystal and polycrystalline silicon". Journal of Materials Research 6, nr 7 (lipiec 1991): 1502–11. http://dx.doi.org/10.1557/jmr.1991.1502.
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The stability of selectively formed TiSi2 films on single crystal and polycrystalline silicon layers at elevated process temperatures is reported. Extensive electrical and analytical studies were performed to understand the high-temperature stability of TiSi2 films as a function of (i) substrate dopant concentration, (ii) titanium silicide thickness, (iii) silicide formation sequence, and (iv) silicide post-processing steps. It is shown that all four process variations have a profound influence on the thermal stability of TiSi2 films. It is observed that titanium silicide films formed on single crystal silicon are stable at higher processing temperatures compared to those formed on polysilicon substrates under similar conditions. The degradation of high-temperature stability of TiSi2 films on polycrystalline silicon can be related to increased number of defects and grain boundaries. It is shown that TiSi2 films can be successfully used in silicon integrated circuit applications where the post-silicide processing temperatures do not exceed 1000 °C.
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Celano, Umberto, Lennaert Wouters, Alexis Franquet, Valentina Spampinato, Paul van der Heide, Marc Schaekers, Abhijeet Joshi i Bulent M. Basol. "Dopant Activation Depth Profiling for Highly Doped Si:P By Scanning Spreading Resistance Microscopy (SSRM) and Differential Hall Effect Metrology (DHEM)". ECS Transactions 108, nr 5 (20.05.2022): 9–15. http://dx.doi.org/10.1149/10805.0009ecst.
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Heavily P-doped epitaxial Si layers were deposited over counter-doped Si substrates. P dopant activation was studied as a function of various processes used to prepare the samples. For electrical characterization, depth profiles of carrier concentration values were obtained using SSRM and DHEM techniques. Samples studied included an in-situ doped sample, a sample that was spike annealed at 1000ºC, a sample that was first coated with a Ti/TiN stack and then annealed for silicide formation before the Ti/TiN stack was removed, and a sample that was spike annealed + coated with Ti/TiN + annealed for silicide formation before the removal of the Ti/TiN stack. DHEM analysis showed substantial increase in dopant activation for spike annealed samples. SSRM results suggested lower carrier concentration values and more limited degree of activation. Formation of Ti/TiN contacts and its removal did not affect the carrier concentration values for the as-deposited epi layer. Sample that was first spike annealed and then subjected to contact formation process displaced a reduction in carrier concentration values as measured by DHEM.
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Liu, Wei-Di, Xiao-Lei Shi, Raza Moshwan, Qiang Sun, Lei Yang, Zhi-Gang Chen i Jin Zou. "Effectively restricting MnSi precipitates for simultaneously enhancing the Seebeck coefficient and electrical conductivity in higher manganese silicide". Journal of Materials Chemistry C 7, nr 24 (2019): 7212–18. http://dx.doi.org/10.1039/c9tc01937e.
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Introducing Mg2Si into higher manganese silicide synthesis successfully suspended the precipitation of MnSi, leading to reduced effective mass, reduced optimized carrier concentration, and enhanced figure of merit, zT.
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Topuria, T., N. D. Browning i Z. Ma. "Characterization of the Source/Drain Region in Mos Devices by Scanning Transmission Electron Microscopy". Microscopy and Microanalysis 7, S2 (sierpień 2001): 210–11. http://dx.doi.org/10.1017/s1431927600027124.
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The advancement of metal-oxide-semiconductor (MOS) technology towards sub- 100nm device dimensions presents several technical difficulties. Nanoscaling in MOS devices is specifically governed by difficulties in the formation of ultrashallow junctions for the source/drain regions with the requirement of low resistance and low leakage currents. The use of a silicide (forming Schottky contacts at the source and drain) instead of the conventional ion implanted Si for the contacts allows a reduction in the contact area to be made, due to lower serial resistance per unit area of the silicide. According to the specific contact resistance dependence on the Schottky barrier height (ΦSB) and active dopant concentration (ND),
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Суворова, Е. И., Ф. Ю. Соломкин, Н. А. Архарова, Н. В. Шаренкова i Г. Н. Исаченко. "Микроструктура и фазовый состав сплава дисилицидов железа и хрома". Физика и техника полупроводников 56, nr 2 (2022): 187. http://dx.doi.org/10.21883/ftp.2022.02.51960.33.
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The phase composition, microstructure, and interphase interfaces of the disordered CrSi2-FeSi2 solid solution obtained by spontaneous crystallization (before and after annealing) have been investigated by scanning, transmission electron microscopy, electron diffraction, and X-ray energy dispersive spectrometry. The as-grown samples contained the phases of CrSi2 with the P6422 hexagonal structure and FeSi2 with the P4/mmm tetragonal structure. Annealing of the samples led to the phase transformation of tetragonal FeSi2 into the orthorhombic modification Cmca. Precipitates of cubic iron monosilicide FeSi with space group P213, nano-precipitates of Si and silicon silicide Cr5Si3 with a tetragonal structure I4/mcm were observed inside the FeSi2 grains. Impurities of interstitial Cr atoms with a concentration up to 2.0 at% are found in iron (di)silicides grains in all samples. The structure of the CrSi2 phase remains unchanged after annealing; the concentration of impurity iron atoms is about 0.7 at%. Orientation relationships between the crystal lattices of the phases are established and strains due to the mismatch of the crystal lattices are determined.
Rozprawy doktorskie na temat "Silicide concentration"
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Emeraud, Thierry. "Etude et modélisation d'un générateur photovoltai͏̈que à forte concentration pour cellules au silicium : contribution à la caractérisation in situ des cellules solaires à concentration". Aix-Marseille 3, 1989. http://www.theses.fr/1989AIX30082.
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L'etude realisee concerne le marche de la production d'electricite photovoltaique sur des installations d'une puissance crete superieures ou egale a 100 kw et sur des sites a fort ensoleillement direct. Les possibilites technico-economiques de la filiere haute concentration sur silicium sont evaluees a court et moyen termes par rapport aux modules plans au si multicristallin. La nature du dispositif optique de concentration et du systeme de refroidissement est definie pour des cellules au si de surface active superieure a 0,5 cm#2 et un taux de concentration superieur a 200 x. Chaque composante est optimisee a partir de mesures experimentales et de modeles analytiques propres. Les options ainsi definies ont ete adaptees a la conception et la realisation d'un banc de mesures de photopiles sous eclairement naturel concentre permanent. Visant a garantir fiabilite et polyvalence maximales, ce dispositif permet la caracterisation de cellules de nature, geometrie et taille diverses. La mise au point du banc est effectuee dans le cadre de l'experimentation de deux cellules si de geometrie carree (surface active: 0,64 cm#2) et a structure de contacts interdigites sur la face arriere (ibc). Le fonctionnement des cellules dans des conditions representatives de leur contexte d'utilisation est analyse au travers de l'obtention de ses parametres externes, et de l'etude de l'evolution de ces parametres en fonction du niveau de flux lumineux incident et de la temperature de jonction
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Liu, Yanan 1981. "Sulfur concentration at sulfide saturation in anhydrous silicate melts at crustal conditions". Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98753.
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The sulfur concentration in silicate melts at sulfide saturation (SCSS) was experimentally investigated in a temperature range from 1250ºC to 1450ºC and a pressure range from 500 MPa to 1 GPa in a piston-cylinder apparatus. The investigated melt compositions varied from rhyolitic to basaltic. All experiments were saturated with a FeS melt. Temperature was confirmed to have a positive effect on the SCSS and no measurable pressure effect was observed. Oxygen fugacity was controlled to be either near the carbon-carbon monoxide buffer or one log unit above the nickel-nickel oxide buffer, and found to positively affect the SCSS. A series of models were constructed to predict the SCSS as a function of temperature, pressure, melt composition, oxygen fugacity and sulfur fugacity of the system. The coefficients were obtained by the regression of experimental data from this study and from data in the literature. The best model found for the prediction of the SCSS is: lnSppm =-996T+9.875+0.997lnMFM+0.1901lnf O2-0.0722&parl0;PT &parr0;-0.115lnfS2 where P is in bar, T is in K, and MFM is a compositional parameter describing the melt based upon cation mole fractions: MFM=Na+K+2 Ca+Mg+Fe2+Six Al+Fe3+.This model predicts the SCSS in anhydrous silicate melts from rhyolitic to basaltic compositions at crustal conditions from 1 bar to 1.25 GPa, temperatures from ~1200 to 1400ºC, and oxygen fugacities between approximately two log units below the fayalite-quartz-magnetite buffer and one log unit above the nickel-nickel oxide buffer. For cases where the oxygen and sulfur fugacities cannot be adequately estimated a simpler model also works acceptably: lnSppm =-5328T+8.431+1.244 lnMFM-0.01704P T+lnaFeS where aFes is the activity of FeS in the sulfide melt and is well approximated by a value of 1. Additional experiments were performed on other basalts in a temperature range from 1250ºC to 1450ºC at 1 GPa to test the models. The model predictions and the measurements of the SCSS agree within 5%. Although I cannot fix exactly the stoichiometric coefficients of the reaction controlling sulfur dissolution, my experiments and models suggest that the solution reaction for sulfur in melts saturated with sulfide is similar to: 8FeSsulfide +3FeOsilicate+4O2-silicat e+2O2gas ⇔4S2-silicate+2S 2gas+11FeOsulfide where the subscripts indicate the phase and O 2- represents "free" oxygens in the silicate melt.
Keywords. sulfur, solubility model, dissolution mechanism, silicate melts
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Serrari, Allal. "Etude de la nitruration thermique, à pression atmosphérique, de l'oxyde de silicium et du silicium". Paris 11, 1989. http://www.theses.fr/1989PA112404.
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Le silicium et l'oxyde de silicium nitrurés présentent de meilleures propriétés diélectriques que l'oxyde de silicium utilisé dans la technologie M. O. S. (métal-oxyde-silicium), d'où l'intérêt de les étudier. La nitruration a été effectuée à pression atmosphérique sous NH3 à haute température (900°C-1100°C) et pendant une durée variant de quelques secondes à 1 ou 2 heures. Pour comprendre le mécanisme de nitruration, nous avons étudié l'influence de plusieurs paramètres de nitruration sur la composition chimique des couches réalisées. La caractérisation physico-chimique a été effectuée par plusieurs technique d'analyse complémentaires telles que : l'analyse par réaction nucléaire, les spectrométries d'électrons Auger et de photoélectrons, la spectroscopie de masse d'ions secondaires et l'ellipsométrie. Nous avons montré que la nitruration du silicium conduit à des couches contenant de l'oxygène. L'épaisseur de ces dernières augmente avec le temps et la température de nitruration mais saturent après une heure (80 A à 1100°C). L'oxyde de silicium nitruré (oxynitrure) présente une surface riche en azote par rapport au volume avec l'existence d’un pic d'azote près de l'inter- face avec le silicium. Nous avons observé ce pic dès 30 secondes pour un oxyde de 450 A, ce qui signifie un coefficient de diffusion de 3. 10-13 cm2/s. Le coefficient de diffusion diminue rapidement, atteint 10-15 cm2/s dès 10 minutes de nitruration. L'incorporation de l'azote dans la couche d'oxyde s'accompagne d'une diminution de la quantité d'oxygène. Le mécanisme de transport atomique de l'oxygène pendant la nitruration a été étudié en utilisant des oxydes isotopiques. Un modèle du mécanisme de nitruration a été proposé. Les mesures capacité-tension à 1 MHZ ont permis de déterminer l'évolution de la tension de bande plate et de la quantité de charges dans la couche. Nous avons mis en évidence les propriétés de barrière à l'oxydation des oxynitrures réalisésThermal nitridation of silicon and oxidized silicon provides best dielectric properties than thin silicon dioxide used in M. O. S. Technology, that is the interest to study them. The nitridation was performed at atmospheric pressure in a furnace under NH3 at high temperature (900°C-1100°C) for various times between 5 secondes and 2 heures. In order to understand the mechanism of nitridation, the influence of several parameters on the chemical composition of the resulting layers has been studied. The physico-chemical characterization was carried-out throught complementary analysis technics such as: nuclear reaction analysis, Auger electron and Xray spectrometries, secondary ion mass spectrometry and ellipsometry. It has been shown that the nitridation of silicon gives layers containing oxygen. Their thickness increases with time and temperature but saturates after one hour (80 A at 1100°C). Nitrided silicon dioxide (oxinitride) is inhomogenous with a nitrogen-rich surface layer and a pile-up of nitrogen at the interface oxinitride/silicon. This pile-up was observed for a 30 secondes nitridation of a 450 A oxide/ that mean a diffusion coefficient of 3. 10-13 cm2/s. The diffusion coefficient decreases rapidly with nitridation time, reach 10-15cm2 /s for 10 minutes. The nitrogen incorporation in the oxide film is accompagned with a de- crease of the oxygen amount. The atomic transport mecanism of oxygen during the nitridation was studied by using isotopique oxides. A model for the nitridation mechanism has been proposed. High frequency (1 MHZ) capacitance-voltage measurements were used in order to determine the flatband voltage and fixed charges in the formed layers. The properties of oxidation-resistance revealed by the layer have been pointed-out
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Benabbas, Tarik. "Activité électrique de bicristaux de silicium élaborés avec un gradient de concentration en aluminium". Paris 11, 1992. http://www.theses.fr/1992PA112473.
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Le but de ce travail est d'aborder l'aspect semi-quantitatif de la recombinaison aux joints de grains dans le silicium, en relation avec leur microstructure. Nous avons pour cela elabore par croissance directionnelle h. E. M. (heat exchange method), en collaboration avec le c. E. C. M. De vitry, des bicristaux de silicium de purete electronique, dotes d'un gradient de concentration en aluminium. Il a ete montre que l'aluminium present en concentration importante dans le semiconducteur, diminue la longueur de diffusion des porteurs minoritaires en se placant sur des sites autres que les sites accepteurs. Precisons tout de meme que l'objectif principal de cette recherche n'est pas tant l'etude du role de l'aluminium dans le silicium, ce sujet ayant fait l'objet de nombreuses etudes, mais plutot, de tenter d'etablir une correspondance, a l'echelle la plus fine possible, entre la microstructure liee a la presence d'une impurete, et l'activite electrique des joints de grains. Nous avons dans ce but entrepris une serie d'observations en microscopie electronique en transmission des joints de grains afin de suivre l'evolution de la microstructure des defauts en relation avec le gradient de concentration en impurete. La microstructure des joints est ensuite correlee a leur comportement electrique au moyen d'une technique d'injection de porteurs sur diodes minces. Cette technique developpee au laboratoire, a permis de montrer avec une resolution spatiale de l'ordre de 100 nm que la recombinaison des porteurs au niveau des joints speciaux dans le silicium, est localisee au niveau des precipites intergranulaires. L'activite electrique des joints de grains est donc essentiellement a caractere extrinseque
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Couderc, Romain. "Etude du comportement thermique et électrique des cellules photovoltaïques en silicium cristallin sous concentration". Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0054/document.
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Le silicium est très utilisé dans la production de cellules photovoltaïques mais très peu pour les applications sous concentration. Il possède pourtant un fort potentiel sous concentration grâce à son faible coût et la maturité de sa filière industrielle. De plus, il est possible d'avoir recours à la cogénération pour augmenter fortement les rendements énergétiques du système. La concentration et la cogénération impliquent un fonctionnement de la cellule à une température plus élevée que les conditions standards de test des cellules photovoltaïques. Cela engendre le besoin de connaître le comportement thermique et électrique de la cellule en fonction de sa température de fonctionnement. La variation de celle-ci, en conditions réelles, est pourtant souvent ignorée. Pour remédier à cette lacune, nous présentons un modèle électro-thermo-radiatif pour les cellules photovoltaïques en silicium cristallin. Il réalise le couplage de l'ensemble des phénomènes physiques prenant place dans une cellule photovoltaïque sous éclairement. Grâce à de nombreuses analyses effectuées dans le cadre des travaux de cette thèse, l'importance du comportement thermique d'une cellule photovoltaïque pour sa conception est mise en évidence. Entre autres, la variation de la température de la cellule avec sa tension que nous avons confirmé expérimentalement grâce à des mesures de température différentes de 2°C entre le Mpp et le Voc. Un des paramètres majeurs influençant le comportement électrique et thermique d’une cellule photovoltaïque en silicium est la densité de porteurs de charge intrinsèque du silicium, ni. Le développement du modèle électro-thermo-radiatif nous a amené à proposer une nouvelle expression semi-empirique de sa variation en fonction de la température. En complément de ces avancées théoriques, la réalisation de cellules photovoltaïques à contacts arrière interdigités implantées ioniquement (3IBC) a été menée. Nous avons diminué le nombre d'étapes nécessaires à sa réalisation et amélioré sa métallisation grâce à un empilement Si/Ti/Ag permettant d'espérer un gain absolu pour le Jsc de 0.72 mA.cm-2. Un rendement de 14.6% a été obtenu sous 1 soleil avec une cellule 3IBC dont la résistance série est de seulement 0.4 Ω.cm2 ce qui confirme le potentiel des cellules 3IBC pour la concentration linéaireSilicon is largely used to produce solar cells but not for applications under concentration. Nevertheless, it has a great potential under concentration thanks to its low cost and the maturity of its industry. Moreover, it is possible to cogenerate electric and thermal power in order to increase the energy output. Cogeneration and concentration imply a higher operating temperature than under standard conditions. Thus, it is interesting to understand the thermal and électrical behavior of the cell as a functiton of its temperature. However the variation of the operating temperature is often ignored. In order to change this, we propose an electro-thermo-radiative model for crystalline silicon solar cells. It couples all phenomenon taking place in an illuminated solar cell. Thanks to this thesis, the importance of the thermal behavior is outlined. For example, the temperature variation as a function of the voltage that we confirmed experimentaly thanks to mesures of the cell temperature at Mpp and at Voc. One of the most important parameters in a silicon solar cell is the intrinsic carrier density, ni. The work on the electro-thermo-radiative model led us to propose a new semi-empirical temperature variation of ni. In addition to these theoretical analysis, we realized ionically implanted interdigitated back contacts solar cells (3IBC). Thanks to this work fewer process steps are needed and the improved metallization (Si/Ti/Ag) possibly lead an absolute Jsc gain of 0.72 mA.cm-2. The efficiency of the best 3IBC cell is 14.6% under 1 sun illumination with a particularly low series resistance (0.4 Ω.cm2) which confirm the potential of such cells for linear concentration
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Crampette, Laurent. "Contribution à la réalisation de cellules photovoltaïques à concentration à base de silicium monocristallin". Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20102/document.
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Les cellules LGBC (Laser Grooves Buried Contact) ont été inventées et développées par M. GRENN au sein de l'UNSW. Elles présentent des contacts métal/silicium enterrés permettant d'optimiser le contact métal/silicium sans augmenter le taux d'ombrage de la cellule. Dans ce manuscrit nous étudierons toutes les étapes clefs nécessaires à la réalisation de ce type de cellules de façon à les rendre industrialisables. Dans un premier temps nous étudierons la réalisation de tranchées dans le silicium via deux lasers (vert & IR). Les paramètres de ces tranchées seront comparées pour sélectionner les plus adaptées à notre technologie en nous assurant qu'il est possible de réaliser une diffusion thermique dans ces tranchées. Nous développerons ensuite deux techniques pour réaliser des émetteurs sélectifs, par double diffusion et par diffusion à travers une couche de nitrure de silicium. Enfin nous étudierons deux méthodes de dépôt de nickel par voie chimique une électrolytique et un electrolessLGBC (Laser Grooved Buried Contact) solar cells was invented and developed by M.GREEN at UNSW. Grooved contact allow to reach a good serial resistivity without incresing the shadowing of the solar cell. In this report we will study the different step necessarry to build this kind of photovoltaic cells. Fisrt we will see the impact of laser effects on silicon and the different parameters to adapte red and green laser for grooved contct. The we will study to way to create selective emitter, on by two diffusion and the second one by diffusion throught a silicon nitride layer. Then we will develope two nickel metallisation one electrolytique and one electroless
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Vandenbossche, Eric. "Contribution à la modélisation de la diffusion des dopants en fortes concentrations dans le silicium". Lille 1, 1994. http://www.theses.fr/1994LIL10158.
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Les phenomenes de diffusion des dopants dans le silicium ont une importance grandissante dans les technologies actuelles et futures. En effet, les budgets thermiques diminuent avec les dimensions des dispositifs, et des phenomenes de diffusion transitoire apparaissent lors de la fabrication de jonctions ultra-courtes p#+/n et n#+/p. Ce memoire traite essentiellement des mecanismes de diffusion, bases sur les reactions entre dopants et defauts ponctuels, lesquels sont les interstitiels (atomes de silicium en site interstitiel) et les lacunes (site substitutionnel vacant). La sursaturation des defauts ponctuels, generee au cours des etapes technologiques (bombardements ioniques, oxydations, nitrurations), gouverne la diffusion transitoire des dopants. Un modele general de diffusion des dopants, incluant l'ensemble des mecanismes entre dopants et defauts ponctuels en non-equilibre, constitue la base de cette etude. Ce modele est presente en detail pour l'arsenic, le phosphore et le bore. Trois applications sur la diffusion du bore et du phosphore sont presentees montrant clairement la contribution des defauts ponctuels a la diffusion transitoire de ces dopants observee experimentalement. L'originalite de ce manuscrit consiste en l'etude des phenomenes de diffusion en fortes concentrations, plus precisement appliquee au bore et dans des conditions de preamorphisation. En effet, le bore presente des phenomenes de diffusion anormaux beaucoup plus marques par rapport aux autres dopants. Trois axes d'etudes constituent le traitement presente dans ce memoire: a) modelisation des conditions initiales pour la simulation en terme de concentrations des defauts ponctuels et activation du profil de dopage implante, b) modelisation des effets des boucles de dislocations generees par les etapes d'amorphisation, ces dislocations jouent le role de puit pour les interstitiels, et c) modelisation de la precipitation du bore, par le phenomene de nucleation derive pour la premiere fois dans un modele general de diffusion.
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Guillo, Lohan Benoit. "Modélisation, élaboration et caractérisation de cellules photovoltaïques à base de silicium cristallin pour des applications sous concentration". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI093/document.
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Les performances électriques des cellules photovoltaïques à base de silicium sont fortement dégradées lorsque leur température augmente. Cette problématique, pourtant bien connue, n’est pas suffisamment prise en considération dans l’industrie du photovoltaïque. Pour parer à cette dégradation, deux voies d’améliorations peuvent être explorées : diminuer la température de fonctionnement des cellules ou réduire leurs coefficients de dégradation en température. Cette étude est d’autant plus importante pour les applications sous concentrations, un éclairement élevé favorisant l’échauffement des cellules. Pour les facteurs de concentration élevés, l’utilisation de systèmes de refroidissement actifs réduit drastiquement la température de fonctionnement. Pour les faibles éclairements, le refroidissement passif est préféré, bien moins coûteux en énergie. Ce travail de thèse est focalisé sur l’étude du comportement thermo-électrique des cellules sous faible concentration du rayonnement incident. Un banc de caractérisation innovant développé dans cette thèse a rendu possible la quantification des variations de la température de la cellule avec la tension de polarisation sous différents facteurs de concentration. Avec l’augmentation de la polarisation, une évolution du facteur d’émission thermique est observée du fait des variations de la concentration de porteurs de charge minoritaires. Le refroidissement radiatif est minimal au courant de court-circuit et est maximal à la tension de circuit ouvert : la température atteinte au point de court-circuit est supérieure à celle atteinte en circuit ouvert. Pour une cellule donnée, sous un éclairement de 3 soleils, un écart de température de 6.2 °C a pu être mesuré entre ces deux points. La fabrication de cellules avec des propriétés différentes nous a permis de confirmer l’importance du dopage de la base et de l’architecture sur l’augmentation du refroidissement radiatif avec la polarisation. De plus, la comparaison du comportement thermo-électrique des cellules de type de dopages différents a mis en avant de plus faibles coefficients de dégradation en température de la tension en circuit ouvert pour les cellules ayant un substrat de type n. Par exemple, pour une température de et sous un éclairement de 1 soleil, un coefficient de dégradation en température du Voc de −0.45% %·°C-1 a été mesuré sur une cellule de type n contre −0.49%·°C-1 pour une cellule de type pThe electrical performances of silicon based solar cells strongly degrade when increasing their temperature. However, such a well-known issue is too scarcely considered in the phovoltaic industry. To prevent the degradation of silicon based solar cells, two ways of improvement can be explored : one can either decrease the cells’ functionning temperature or either reduce the temperature degradation coefficient. As light intensity tends to favor cell heating, the study is even more important under concentrated sunlight. Regarding high light intensities, active cooling systems can be used to drastically reduce the cell temperature. For low light intensities, passive cooling systems, such as radiative cooling, are more energetically savy. The thesis aims at studying the electro-thermal behavior of cells under low light intensities. An innovative experimental set-up has been developped during this thesis to quantify the variation of the cell temperature with the applied bias voltage. When increasing the bias, an evolution of the cell emissivity is observed because of a variation of the minorities carrier concentration. The radiative cooling is at its lowest at the short circuit current and peaks its highest value at the open circuit voltage : as a result, the reached temperature is higher at the short circuit current than at the open circuit voltage. For a given solar cell, under 3 suns, a temperature shift of 6.2 °C was measured between these two points. The control of the fabrication process gives the opportunity to analyse the influence of the base doping and cell architecture on the evolution of the radiative cooling with the applied bias. Furthermore, the comparison between the electro-thermal behaviors of solar cells, which are related to their type of doping, has shown a lower thermal degradation coefficient of the open circuit voltage for n-type based dope solar cells. For example, at 60°C and under 1 sun, we measured a thermal degradation coefficient BVoc = −0.45% %·°C-1 for a n type solar cell whereas the p type solar cell recorded BVoc = −0.49% %·°C-1
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Pavlov, Marko. "Modélisation numérique du couplage thermique-photoélectrique pour des modules photovoltaïques sous faible concentration". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS361/document.
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La faible exploitation de l'irradiation inter-rangée limite la production des modules photovoltaïques (PV). Le projet "Aleph" explore l'intérêt d'ajouter des réflecteurs plans entre les rangées pour augmenter la production, et dégage des règles claires permettant l'optimisation géométrique de l'ensemble. Ce travail présente une modélisation multiphysique du système, des simulations numériques de son comportement, et la comparaison avec des données expérimentales. Deux technologies de module PV sont considérées : silicium amorphe (a-Si) et silicium polycristallin (p-Si). Les mesures montrent des gains énergétiques importants grâce aux réflecteurs. Les gains sont plus importants pour les modules a-Si que p-Si. La modélisation associe un modèle optique de lancers de rayons par méthode Monté-Carlo sous EDStaR, un modèle photoélectrique sous SPICE, et un modèle thermique empirique. Le modèle complet est calibré avec des données expérimentales en utilisant un algorithme évolutif. Une fois calibré, le modèle démontre une bonne performance en simulant la puissance générée par les modules en fonction des données atmosphériques et radiativesThe poor utilisation of the inter-row irradiation limits the production of photovoltaic (PV) modules. The "Aleph" project explores the potential of adding inter-row planar reflectors to increase the system yield, and defines clear rules for optimal settings of such systems in a given location and under a given climate. This work presents a multiphysics model of the system, numerical simulations of its behaviour, and the comparison with experimental data. Two PV module technologies are tested: amorphous silicon (a-Si) and polycrystalline silicon (p-Si). The experimental data show significant gains in produced energy brought by the reflectors. The gains are higher for a-Si modules compared to p-Si. The modelling work combines a Monte-Carlo ray-tracing optical model (EDStaR), a photo-electric model (SPICE), and an empirical thermal model. The complete model is calibrated with measurements using an evolutionary algorithm. Once calibrated, the model demonstrates good performance in predicting the module power output as a function of atmospheric and irradiance data
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Vahanian, Elina. "Développement de couches antireflets à base de nanoparticules de silice pour des systèmes photovoltaïques à haute concentration". Doctoral thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/28212.
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Le sujet d’étude de cette thèse porte sur la recherche et le développement d’une couche antireflet (ARC) qu’il serait possible de déposer sur des surfaces à structure particulière (non plane). Plus spécifiquement, il s’agit de surfaces d’éléments optiques utilisés dans des systèmes de concentrateurs photovoltaïques (CPV). Ce projet de recherche a été initié par la compagnie Opsun Technologies Inc. suite à un constat de phénomène de réflexion introduite à l’ajout d’éléments optiques hautement focalisant dans leur système de CPV (que l’on va appeler HCPV par la suite). En effet, pour concentrer le rayonnement solaire sur une cellule photovoltaïque (PV), il est nécessaire d’ajouter une lentille focalisant le rayonnement (lentille de Fresnel). De plus, afin de se garantir une réception de tout le rayonnement nécessaire à la cellule PV, une composante de type guide d’onde est ajoutée. A la fois pour l’homogénéisation du rayonnement incident sur la cellule, mais surtout (dans le cas d’Opsun) pour avoir un angle d’acceptance (du rayonnement focalisé) plus large (±3.2° au lieu des ±0,5° à ±1° usuels). Ainsi, le phénomène de réflexion qui se produit à la surface de cet élément optique, lui enlève toute propriété pour laquelle il a été prévu. Le but du projet consiste alors en l’élimination de ces réflexions en utilisant une méthode de production et de déposition d’ARC, qui soit industrialisable. Dans un premier temps, différents moyens de production et de déposition d’ARC déjà existant ont été investigués. Toujours gardant en tête qu’ils doivent pouvoir être appliqués sur des surfaces particulières tout en restant industrialisables par la suite. Nos études nous ont montrées que ces méthodes classiques ne remplissent pas la condition exigée. Il a alors été décidé de rechercher des moyens de production d’ARC basées sur l’utilisation de nanostructures (NS) ou encore des couches à base de nanoparticules (NP). Dans un deuxième temps, une ARC composée de NS (fournit par l’institut Fraunhofer) a été étudiée en condition de laboratoire afin de connaître ses propriétés optiques (transmission, réflexion, diffusion). Ceci fait, la NS a été introduite dans le système HCPV et des mesures de rendement électrique ont alors été réalisées en temps réel. La NS a bien démontré une diminution de la réflexion sur l’ensemble de la longueur d’onde que nous visions (380-1500nm) qui a augmenté de 91,6% (sans AR) à 98,7% , ce qui s’est également traduit en une augmentation du rendement du système HCPV qui étaient de 5%. La NS reste néanmoins encore une méthode de laboratoire et demande beaucoup de conditions particulières afin d’être produite sur les surfaces que nous avons, augmentant considérablement son coût de production (voir en Annexe 8.1). Il a alors été décidé d’investiguer des ARC à base de NP, qui démontrent une meilleure satisfaction des exigences mentionnées précédemment. Ainsi, une troisième étape a consisté en la production et l’utilisation de NP de silice afin de produire des couches AR. En effet, une méthode bien connue de production de particules de silice a été utilisée pour l’obtention des NP, qu’est la méthode sol-gel. Par la suite, la suspension de NP produite a été déposée sur des surfaces de verre et de PMMA en utilisant une méthode de revêtement par immersion (angl. : dip coating (DC)) et leurs propriétés optiques ont été étudiées. Dans le cas présent, nous avons constaté que selon l’épaisseur d’ARC, nous avons une réflexion qui a été diminuée sur l’ensemble de la bande de longueur d’onde observé (380-1500nm). Il est à noter que, bien que l’on ait une certaine diminution sur la bande mentionnée, l’on observe une diminution maximale de la réflexion plus remarquable sur une bande de longueur d’onde spécifique. De plus, si l’on augmente l’épaisseur de l’ARC, il y a un décalage de cette diminution maximale vers les grandes longueurs d’onde. Si nous comparons les bandes de longueurs d’onde où la diminution est maximale (principalement dans le visible, entre 400nm et 800nm), nous pouvons constater que celle-ci augmente de 92,1% (sans AR) jusqu’à 99,2% suivant les épaisseurs d’ARC. Ces couches AR ont ensuite été ajoutés dans le système HCPV. Il a été observé que le rendement des HCPV ne suit pas une augmentation graduelle suivant l’augmentation de l’épaisseur de l’ARC, contrairement à ce qui été attendu. En effet, il atteint un maximum pour une épaisseur particulière (dans ce cas-ci environ 130nm (ARC4 dans Chapitre 3)) avant de diminuer à nouveau. La valeur du rendement maximal mesuré est comparable à ce qui était obtenu précédemment en utilisant les ARC à base de NS (5%). La variation des valeurs de rendement en fonction de l’épaisseur est due aux propriétés des cellules PV (multijonctions (MJ)) qui sont utilisées dans les HCPV (voir Chapitre 3 pour l’explication). Ainsi, dépendamment de l’ARC que nous pouvons produire et de la cellule MJ choisie, il sera possible d’optimiser le rendement des systèmes HCPV, selon leurs conditions d’utilisations. Pour finaliser ce projet, des tests environnementaux (accélérés) ont également été réalisés sur les ARC dans le but de connaître leur résistance mécanique, environnementale (température) ainsi qu’aux rayonnements UV, pour la même période de garantie du HCPV. Les résultats obtenus démontraient une diminution de l’efficacité de l’ARC de l’ordre de 3% en fin de test environnemental et une diminution de 1,5% pour les tests UV sur les petites longueurs d’onde (< 500nm). Ce qui reste bien inférieur aux pertes de rendement de systèmes CPV prévus par les tests standards, qui est de 20% en 25ans.The subject of this thesis is to focus on the research and development of an antireflective coating (ARC) to coat surfaces with specific structuration (not plane). The surfaces in question are those of optical components used in high concentrating photovoltaic (HCPV) systems. This project has been initiated by Opsun Technologies Inc. after they were experiencing reflection phenomena when the concentrating optical components were added in the system. Indeed, to concentrate light on a photovoltaic (PV) cell, it is essential to use a lens (Fresnel lens). Furthermore, to ensure reception of all the incident wavelengths, a second optical component is added in the HCPV system. It can be assimilated to a waveguide, which is aimed to homogenize the rays. More importantly, it has the property to increase the angular aperture of the received light (±3.2° instead of the usual ±0,5° à ±1°). Thus, adding this second optical component, added a reflection phenomenon due to the extra interface, preventing the component to be used for its initial property. The aim of this project is thus to produce an ARC and coat these surfaces with a specific method, the whole processes must be industrializable at the same time. Hence, a first step was aimed to investigate different existing ARC production and coating methods that can correspond to our required properties. Classical ARC production methods have quickly been considered as non-eligible, therefore new methods have been explored such as nanostructured (NS) ARC or coatings based on nanoparticles (NP). In a second part of the work, a NS (kindly provided by the Fraunhofer institute), was studied in laboratory conditions, to know its optical properties (transmission, reflection, scattering). Afterwards, it was introduced in the HCPV system to get real-time studies of the electrical performance. The NS did show an increase in the optical transmission, on the whole wavelength ranges we are interested in (350-1500nm), which increased from 91,6% (without AR) up to 98,7% , which resulted in a direct increase of the electrical performance of the HCPV that was about 5%. Anyways, the NS is still a method developed and used on a laboratory level and requires a lot of specific production conditions, increasing its final coast (see Appendix 8.1). Thus, it was decided that coatings based on NP needed also to be investigated. A third step of this work was then to produce ARC based on silica NP using a well-known production method, which is the sol-gel process. The obtained NP were then deposed by a homemade dip coating (DC) method on glass and PMMA slides and their optical properties were studied (on a wavelength band varying from 380 to 1500nm). In this case, we also noticed an increase in the transmission, which was totally dependent on the ARC thicknesses. Indeed, a shift of the maximum transmission towards higher wavelengths was observed when the ARC thickness increased. It is important to mention that, even though a certain transmission increase on the considered wavelengths was obtained, a maximum increase on a specific wavelength (in the visible wavelengths, from 400nm to 800nm) band was observed for each ARC (or thickness). Those maximum transmissions of the different ARC, when compared, showed an increase from 92,1% (without AR) up to 99,2% depending on the ARC thickness. When the ARC were added in the HCPV system, the response of the electrical performance did not increase gradually, depending of the increase of the coating thickness, which was our expectation. Instead, it reached a maximum for a specific thickness (around 130nm (ARC4 in Chapitre 3)), before it decreased when higher thicknesses were used. The maximum electrical output value obtained has been found to be comparable to the results obtained using the NS (5%). This phenomenon can be explained by the specific properties of the PV cells (multijunction (MJ), see Chapitre 3 for the explanation). Thus, for a specific PV cell a specific ARC can be produced to optimize the electrical yield of the HCPV system, depending on the conditions they are used in. An ultimate step consisted in the environmental testing (accelerated tests) of our obtained ARC, to have information about their resistance in terms of mechanical deterioration, temperature and UV variation, for the same lifetime warranty of CPV systems. The results obtained showed a decrease of the ARC efficiency that was about 3% at the end of the temperature tests and a 1,5% variation of the transmission was observed after the UV tests for small wavelengths (< 500nm). This is relatively low compared to the warranty of CPV system efficiencies that are expected to decrease about 20% in 25 year lifetime.
Książki na temat "Silicide concentration"
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B, Lowenstern Jacob, i Geological Survey (U.S.), red. Major-element, trace-element, and volatile concentrations in silicate melt inclusions from the tuff of Pine Grove, Wah Wah Mountains, Utah. [Menlo Park, Calif.?]: U.S. Dept. of the Interior, U.S. Geological Survey, 1994.
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B, Lowenstern Jacob, i Geological Survey (U.S.), red. Major-element, trace-element, and volatile concentrations in silicate melt inclusions from the tuff of Pine Grove, Wah Wah Mountains, Utah. [Menlo Park, Calif.?]: U.S. Dept. of the Interior, U.S. Geological Survey, 1994.
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B, Lowenstern Jacob, i Geological Survey (U.S.), red. Major-element, trace-element, and volatile concentrations in silicate melt inclusions from the tuff of Pine Grove, Wah Wah Mountains, Utah. [Menlo Park, Calif.?]: U.S. Dept. of the Interior, U.S. Geological Survey, 1994.
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B, Lowenstern Jacob, i Geological Survey (U.S.), red. Major-element, trace-element, and volatile concentrations in silicate melt inclusions from the tuff of Pine Grove, Wah Wah Mountains, Utah. [Menlo Park, Calif.?]: U.S. Dept. of the Interior, U.S. Geological Survey, 1994.
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B, Lowenstern Jacob, i Geological Survey (U.S.), red. Major-element, trace-element, and volatile concentrations in silicate melt inclusions from the tuff of Pine Grove, Wah Wah Mountains, Utah. [Menlo Park, Calif.?]: U.S. Dept. of the Interior, U.S. Geological Survey, 1994.
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Low earth durability evaluation of protected silicone for advanced refractive photovoltaic concentrator arrays. [Washington, DC]: National Aeronautics and Space Administration, 1994.
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Thermal history effects on electrical relaxation and conductivity for potassium silicate glass with low alkali concentrations. [Washington, DC: National Aeronautics and Space Administration, 1993.
Znajdź pełny tekst źródłaCzęści książek na temat "Silicide concentration"
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Moodley, M. K., K. Bharuth-Ram, H. De Waal i R. Pretorius. "CEMS Investigations of Fe-Silicide Phases Formed by the Method of Concentration Controlled Phase Selection". W Industrial Applications of the Mössbauer Effect, 589–95. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0299-8_64.
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Caullet, P., i J. L. Guth. "Observed and Calculated Silicate and Aluminosilicate Oligomer Concentrations in Alkaline Aqueous Solutions". W ACS Symposium Series, 83–97. Washington, DC: American Chemical Society, 1989. http://dx.doi.org/10.1021/bk-1989-0398.ch006.
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Yan, Peng, Guifang Zhang, Bo Li, Lei Gao, Zhe Shi, Hua Wang i Yindong Yang. "Experimental Study of Pre-concentration from Silicate Containing Rare Earth Ore with Scandium by Magnetic Separation". W Light Metals 2019, 1415–20. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05864-7_177.
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Tchero, Huidi. "Management of Scars in Skin of Color". W Textbook on Scar Management, 371–77. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-44766-3_43.
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AbstractKeloids and hypertrophic scars are abnormal scars, produced by an odd wound-healing response to trauma with a higher incidence in pigmented skin patients. They could be painful or itchy, producing functional and/or cosmetic disability. This chapter focuses on defining scars especially in pigmented skin and the different methods for treating keloids that have been investigated in the literature. Up to the present time, the ideal treatment method has not been defined, although numerous modalities have been designated. We will represent the variances among different scar types and their management methods, concentrating on their indications, modes of action, uses, safety, and efficiency of the following therapies: intralesional steroid, injections of silicone gel/sheet, radiotherapy, photodynamic therapy, electrical stimulation, surgical excision and adjuvant therapy, and cryosurgery. Combination therapies have also shown some value. Still, there is a shortage of randomized clinical trials (RCTs) evaluating such treatment modalities. Management of scar in pigmented (colored) skin is clinically challenging. Therefore, strategic assessment and targeted therapy with focus on deterring recurrence are most needed. The quality of evidence is crucial to select efficient treatments for patients with colored skin, presenting with keloid.
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Sadeghi, Hatef, i Sara Sangtarash. "Silicene Nanoribbons and Nanopores for Nanoelectronic Devices and Applications". W Handbook of Research on Nanoelectronic Sensor Modeling and Applications, 39–69. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-0736-9.ch003.
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Given the compatibility of silicene with existing semiconductor techniques, and a need for new materials to continue Moore's low, it is natural to ask if this material can form a platform as field effect transistor. Here we provide analytical models to study the electrical properties of two dimensional silicene such as electrical conductance, carrier concentration, mobility and magneto-conductance. Furthermore, we show that silicene nanoribbons and nanopores can be used as a discriminating sensor for DNA sequencing and for efficient thermoelectric power generation.
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Gharzouni, Ameni, Clément Alizé i Sylvie Rossignol. "Fire Resistant Geopolymers Based on Several Clays Mixtures". W Clay and Clay Minerals [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98566.
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This chapter aims to highlight the effect of clay mixture mineral composition and alkali concentration of potassium alkaline solutions on the thermal behavior of geopolymer materials. For this, three mixtures composed of kaolin (pure, impure kaolin or mixture of both), calcium carbonate, sand and potassium feldspar and three potassium alkaline silicate solutions with different concentrations were used (5, 6 and 7 mol.L−1). At first, the effect of rotary calcination parameters at 750°C such as the dwell time (30, 60, 120 and 180 min) and weight powder (100, 400 and 500 g) was investigated. It was demonstrated that the kaolin dehydroxylation is quasi complete (> 90%) and do not significantly depend on the dwell time and powder weight. Whereas the carbonate decomposition degree increases with the increase of dwell time and the decrease of powder weight but still not complete (<80%). These differences influence the feasibility of consolidated materials. Indeed, a flash setting occurs for samples based mixtures with high calcium carbonate decomposition degree (> 50%) and low wettability values (500 μL/g) for the three used alkaline solutions. The thermal behavior at 1000°C depends on the chemical composition of the aluminosilicate source and the concentration of alkaline solution. A conservation of the compressive strength at 43 MPa after thermal treatment at 1000°C of geopolymers based on mixture of pure and impure kaolin and a low potassium concentration solution (5 mol.L−1) was evidenced.
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Ahmad, Ijaz, Jeremy P. Richards, D. Graham Pearson, Jingao Liu, Sarah-Jane Barnes, Pedro J. Jugo, Muhammad T. Shah, Matthew Leybourne i Oliver Jagoutzs. "Fractionation of Sulfide Phases Controls the Chalcophile Metal Budget of Arc Magmas: Evidence from the Chilas Complex, Kohistan Arc, Pakistan". W Tectonomagmatic Influences on Metallogeny and Hydrothermal Ore Deposits: A Tribute to Jeremy P. Richards (Volume II), 297–310. Society of Economic Geologists, 2021. http://dx.doi.org/10.5382/sp.24.16.
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Abstract Some arc magmas lead to the formation of porphyry deposits in the relatively shallow upper crust (<5 km). Porphyry deposits are major sources of Cu and an important Au source but lack significant amounts of platinum group elements (PGE). Sulfide phases control the behavior of chalcophile elements and affect the potential to form ore deposits either by remaining in the mantle residue or by fractionating from arc magmas at lower crustal levels, although in detail the role of sulfide saturation in the lower crust remains poorly understood. Lower crustal cumulate rocks from the 85 Ma Chilas Complex of the Kohistan arc, Pakistan, provide insight into processes that occur at depth in arcs. Here we provide Cu, Ni, Au, and PGE concentrations and Os isotope ratios of the Chilas Complex in order to constrain the extent of sulfide saturation in the lower crust and the effect of sulfide saturation on the metal budget of evolved melts that ascend to the upper crust. The Chilas rock suite contains less than 0.17 wt % sulfides and low PGE concentrations. In situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) measurements of the sulfide inclusions in silicate minerals show enrichment in several chalcophile elements (up to 34 wt % Cu, 23 ppm Au, 245 ppm Pd, and 20 ppm Pt), whereas iridium group PGE (IPGE- Os, Ir, Ru) are mainly below detection limits. The metal content of the parental melt was modeled based on the elemental concentrations of the sulfides. The modeled parental arc magmas contain 70 to 140 ppm Cu, 0.2 to 1.5 ppb Au, and 1.2 to 8 ppb Pd, but low concentrations of IPGE, suggesting that IPGE were likely retained in the mantle source. Mass balance calculations show that segregation of a sulfide melt in the lower crust could further deplete the melt by more than 95% in Pd and Pt, 33 to 85% in Au, and 13 to 60% in Cu. Thus, magmas that ascend to the upper crust would contain very low concentrations of Au (< 0.2 ppb) and Pd (< 0.04 ppb), but they would retain sufficient concentration of Cu (~45–57 ppm) to form porphyry Cu deposits upon emplacement in the upper crust, as is commonly observed in arc settings.
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Alexander, Earl B., Roger G. Coleman, Todd Keeler-Wolfe i Susan P. Harrison. "Mineralogy and Petrology of Serpentine". W Serpentine Geoecology of Western North America. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195165081.003.0006.
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“Serpentine” is used both as the name of a rock and the name of a mineral. Mineralogists use “serpentine” as a group name for serpentine minerals. Petrologists refer to rocks composed mostly of serpentine minerals and minor amounts of talc, chlorite, magnetite, and brucite as serpentinites. The addition of “-ite” to mineral names is common practice in petrologic nomenclature. For instance, quartzite is a name for a rock made up mostly of quartz. Serpentinites are rocks that form as a result of metamorphism or metasomatism of primary magnesium–iron silicate minerals. This entails the replacement of the primary silicate minerals by magnesium silicate serpentine minerals and the concentration of excess iron in magnetite. “Mafic” is a euphonious term derived from magnesium and ferric that is used for dark colored rocks rich in ferromagnesian silicate minerals. “Ultramafic” is used when the magnesium–ferrous silicate minerals compose >90% of the total rock. Olivine, clinopyroxene, and orthopyroxene are the minerals in primary ultramafic rocks, with minor amounts of plagioclase, amphibole, and chromite. Ultrabasic has been used by some geologists in referring to ultramafic rocks. The most common ultramafic rocks are harzburgite, containing <75% olivine and 25% orthopyroxene; dunite, with 100% olivine; and lherzolite, which has 75% olivine, 15% orthopyroxene, and >10% clinopyroxene, with or without plagioclase. Very small amounts of chromite are present in all of the mantle ultramafic rocks (Coleman 1971). The alteration of primary ultramafic rocks to serpentine mineral assemblages is incremental due to episodic invasion of water into the ultramafic rock. It is difficult to distinguish and map the gradations from primary ultramafic rock to serpentinite. Because of this difficulty in distinction, we prefer to use the term ultramafic or serpentinized peridotite for all gradations to serpentinite. Pedologists and botanists commonly group serpentinites with primary ultramafic rocks and refer to these substrates as serpentine because all of them have similar chemical compositions. As will become apparent later, there is great variability in the mineralogical compositions of these rocks and the soils derived from them.
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Onutai, Sujitra, Sirithan Jiemsirilers i Takaomi Kobayashi. "Geopolymer Sourced with Fly Ash and Industrial Aluminum Waste for Sustainable Materials". W Applied Environmental Materials Science for Sustainability, 165–85. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-1971-3.ch008.
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Geopolymer is alumino-silicate material which can apply for many applications due to that geopolymers have several attractive properties of high strength, low permeability, high acid resistance, hazardous materials, and immobilization of toxic materials. This chapter presents synthesis of the dense and the porous structures of geopolymer by using fly ash and industrial waste as the raw materials. Aluminum hydroxide waste (Al-waste) and fly ash (FA) were used to synthesis the dense geopolymers for cement materials. The Al-waste based geopolymer influenced the geopolymer strength, when sodium hydroxide (NaOH) concentration was changed at different curing temperatures. As preliminary microwave oven was exposed in the lower NaOH paste of geopolymer, the successful synthesis of geopolymer cement was obtained. In addition, porous fly ash geopolymers was achieved using a household microwave oven. The geopolymer paste was cured within 1 min by using a microwave oven at different output power. Porous geopolymers were formed immediately as ued at 850 W power of the microwave oven.
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Onutai, Sujitra, Sirithan Jiemsirilers i Takaomi Kobayashi. "Geopolymer Sourced with Fly Ash and Industrial Aluminum Waste for Sustainable Materials". W Waste Management, 676–96. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-1210-4.ch032.
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Geopolymer is alumino-silicate material which can apply for many applications due to that geopolymers have several attractive properties of high strength, low permeability, high acid resistance, hazardous materials, and immobilization of toxic materials. This chapter presents synthesis of the dense and the porous structures of geopolymer by using fly ash and industrial waste as the raw materials. Aluminum hydroxide waste (Al-waste) and fly ash (FA) were used to synthesis the dense geopolymers for cement materials. The Al-waste based geopolymer influenced the geopolymer strength, when sodium hydroxide (NaOH) concentration was changed at different curing temperatures. As preliminary microwave oven was exposed in the lower NaOH paste of geopolymer, the successful synthesis of geopolymer cement was obtained. In addition, porous fly ash geopolymers was achieved using a household microwave oven. The geopolymer paste was cured within 1 min by using a microwave oven at different output power. Porous geopolymers were formed immediately as ued at 850 W power of the microwave oven.
Streszczenia konferencji na temat "Silicide concentration"
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Foresi, James S., Rick Hoffman, David King i Patrick Ponsardin. "Performance of silicone-on-glass Fresnel lenses in EMCORE's Gen 3 high-concentration concentrator photovoltaic system". W SPIE Solar Energy + Technology, redaktorzy Kaitlyn VanSant i Adam P. Plesniak. SPIE, 2012. http://dx.doi.org/10.1117/12.929348.
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Gehring, Brian, i Fletcher Miller. "Modeling of a High-Temperature Latent Heat Thermal Storage Module for Brayton Cycle Applications". W ASME 2012 6th International Conference on Energy Sustainability collocated with the ASME 2012 10th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/es2012-91237.
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Concentrating solar power (CSP) plants with thermal energy storage offer several advantages to plants without storage. Thermal energy storage (TES) allows CSP plants to produce power for longer periods of time each day, making them produce energy more like traditional, fossil fuel power plants. TES also gives the ability to time shift production of energy to times of peak demand, allowing the plant to sell the energy when prices are highest. A CSP plant with storage can increase turbine performance and reach higher levels of efficiency by load leveling production and can remain productive through cloud transients. Power tower CSP plants are capable of producing extremely high temperatures, as they have the ability to oversize their solar field and achieve a greater concentration ratio. Studies have been conducted on variable working fluids, leading to higher working temperatures. This theoretically allows power towers to use more efficient, higher temperature cycles including the recuperated air Brayton cycle, although none currently exist on a commercial scale. This research focuses on developing a model of a high temperature TES system for use with an air Brayton cycle for a power tower CSP plant. In this research we model one module of a latent heat TES system designed to meet the thermal needs of a recuperated Brayton engine of 4.6 MWe capacity for six hours. A metal alloy, aluminum-silicide (AlSi), is considered as the phase change medium. The storage tank is approximately 161 m3, or a cylinder with a 5 m diameter that is 8 m tall filled with AlSi with several air pipes throughout the volume. We model the volume around a single pipe in a 2-D cylindrical coordinate system, for a module size of 0.2 m in diameter and 8 m long. The advantages of using AlSi alloys is that they have variable melting temperatures depending on the relative concentration of the two metals, from 577 C for the eutectic composition of 12.6% silicon to 1411 C for 100% silicon. This attribute is taken advantage of by the TES model as the composition of the AlSi alloy will vary axially. This will allow a cascaded type storage system within one tank and with one material. The use of FLUENT to model this problem is first validated by several analytical solutions including Neumann’s exact solution for a one-dimensional Cartesian geometry and the Quasi-Steady Approximation in a 1-D cylindrical geometry. The model developed will establish charge/discharge times for the storage system, round-trip efficiency of the system, ability of the system to meet the demand of the Brayton cycle, and the validity of using off-eutectic metal alloys in a cascade as a latent heat TES medium.
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Sasagawa, Tsuyoshi, Taiji Chida i Yuichi Niibori. "Effects of Temperature on Deposition Rate of Supersaturated Silicic Acid on Ca-Type Bentonite". W 2016 24th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icone24-60468.
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For the disposal system of high-level radioactive waste in Japan, Na-type bentonite is used as one of backfilling and buffer materials for preventing the migration of groundwater and radionuclide. However, the alteration to Ca-type bentonite will cause the degradation of the barrier performance. On the other hand, silicate minerals around the repository dissolve under the high alkaline condition of groundwater (about pH 13) altered by alkaline components leaching from cementitious materials used for the construction of the repository. Such high-concentration silicic acid becomes supersaturated with the decrease in pH by mixing with natural downstream groundwater (pH 8) because of the change in the solubility of silicic acid. So far, the authors have examined the deposition rates of supersaturated silicic acid on Ca-type bentonite under the condition of room temperature, showing the clogging effect of flow-paths with the deposition. However, the dynamic behaviors of silicic acid are much sensitive to temperature change. Therefore, the present study focuses on the effect of temperature on the deposition rate of silicic acid on Ca-type bentonite. As a result, in the range up to 323 K, the deposition of supersaturated silicic acid on Ca-type bentonite was promoted with the increase in temperature. This suggests that the deposition of silicic acid will clog the flow-paths in Ca-type bentonite in this temperature range.
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Nageno, Y., Jae H. Kyung i N. M. Lawandy. "Efficient Photo-induced Second Harmonic Generation in Ternary Barium Borosilicate and Pure Binary Lead-silicate Glasses". W Photosensitivity and Quadratic Nonlinearity in Glass Waveguides. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/pqn.1995.sac.4.
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Most studies of photo-induced efficient second harmonic generation (SHG) in bulk glass systems are currently being performed with commercial glasses which are highly impure. The existence of impurities, even trace amounts, can significantly affect the photo-induced SHG characteristics in glasses as demonstrated in experiments performed on Ce-doped lead germanate glasses [1]. In fact, it was shown that Ce concentration as low as 0.2% was enough to cause a significant increase in SHG in these glasses. Therefore, it is advantageous to study glass systems that are devoid of impurities and consistent in composition in order to gain a better insight into the role of the glass matrix in photo-induced SHG. In a series of experiments performed by Dianov, et al [2], the effect of PbO concentration on SHG was studied using commercial lead-silicate glasses with different lead-oxide concentrations. They found a peaked correlation between lead concentration and SHG power at approximately 21 mol % PbO. However, the effects due to the presence of impurities and variations in composition in different lead-silicate glasses were not addressed. In this study, we measured compositional dependence on SHG characteristics on pure binary lead-silicate and pure ternary barium borosilicate glass systems.
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Cui, Sifang, Nicholas Lyons, Kyung-Jo Kim i Robert A. Norwood. "Silicone optical elements for cost-effective solar concentration". W Optics for Solar Energy. Washington, D.C.: OSA, 2018. http://dx.doi.org/10.1364/ose.2018.ow3d.3.
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Carlton, Hayden, Ange Iradukunda, David Huitink, Sarah Myane, Noah Akey, Asif Imran i Fang Luo. "Multifunctional Magnetic Nanocomposite Encapsulant for EMI Shielding in Power Electronics". W ASME 2020 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/ipack2020-2576.
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Abstract As power densities and switching frequencies dramatically increase, a potential area of advancement for encapsulant technologies is to utilize them to mitigate electromagnetic interference, which directly impacts device efficiency at high switching frequencies; one promising topic involves the creation of magnetic nanoparticle-enhanced encapsulants, with intrinsic sensitivity to electromagnetic fields that could provide additional noise shielding for power electronic devices. A nanocomposite encapsulant was created by directly incorporating magnetic iron oxide nanoparticles into a silicone matrix. The nanoparticles, with an average size of 100 nm, achieved excellent dispersion in the silicone polymer, even at high concentrations, with no additive or surfactants needed to improve stability. Material testing, including thermo mechanical analysis and thermal conductivity measurements were performed to determine if the addition of the nanoparticles altered the thermal or mechanical properties of the base silicone. The nanocomposites at different concentrations observed thermal conductivities of 0.5 W/m-K and coefficient of thermal expansions of 280 ppm/°C, which resembles that of normal silicone; however, the addition of the iron oxide reduced the dielectric breakdown strength of the silicone matrix exponentially with respect to concentration from 20 kV/mm to 3 kV/mm. Further efforts to optimize the dielectric properties of the nanocomposites with respect to the nanoparticle loading is necessary in order to directly apply this technology; however, the results indicate magnetic nanocomposites could be a potential avenue towards mitigating electromagnetic interference in power devices.
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Velderrain, Michelle, Frank Dimroth, Sarah Kurtz, Gabriel Sala i Andreas W. Bett. "Choosing a Silicone Encapsulant for Photovoltaic Applications". W 7TH INTERNATIONAL CONFERENCE ON CONCENTRATING PHOTOVOLTAIC SYSTEMS: CPV-7. AIP, 2011. http://dx.doi.org/10.1063/1.3658299.
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Okuhara, Yoshiki, Tomohiro Kuroyama, Daisaku Yokoe, Takeharu Kato, Masasuke Takata, Takuhito Tsutsui i Kazuto Noritake. "Solar selective absorbers consisting of semiconducting silicide absorbing layers with thermally stabilized Ag base". W SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5117631.
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Tiedemann, K. H. "Time Series Modeling of Silicate Concentration and Silicate Flux in the Lower Yangtze River, 1963-1987". W Modelling and Simulation. Calgary,AB,Canada: ACTAPRESS, 2010. http://dx.doi.org/10.2316/p.2010.699-002.
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Liu, Fang. "Extraordinary Enhancement of Forced Convective Heat Transfer in Dilute Oil-in-Water Emulsions". W ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23035.
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Abstract In this study, flow and heat transfer characteristics of the dilute oil-in-water emulsions containing micrometer-sized dimethyl silicone oil droplets with different concentrations are investigated experimentally in a helically coiled tube. Forced convective heat transfer of emulsions can be enhanced significantly by low-concentration oil droplets although thermal conductivity of oil is much lower than that of water. Pressure drop of low-concentration emulsions can be lower than that of the water base fluid in laminar flow region. Early onset of transition to turbulence for oil-in-water emulsions occurs compared to pure water in a heated tube. The largest thermal performance factor is 1.044 at oil mass fraction of 0.5% and at Re around 3500. This study could be helpful for exploring a new heat transfer media with large heat transfer enhancement at a slight or even negative increase of pumping energy consumption by adding low-concentration oil droplets.