Análise de processos de oxidação com Trans-LC para fabricação de células solares

Apesar do filme para passivação padrão da indústria de células solares atual ser SiNx, as últimas tendências do mercado fazem com que seja necessário reavaliar o SiO2 para passivação das superfícies de células solares. Para crescer estes óxidos, no entanto, são necessárias etapas de processamento em altas temperaturas, que deixam as lâminas de silício suscetíveis a contaminações metálicas. Para evitar essa contaminação, o composto orgânico Trans-LC é utilizado para limpeza do tubo de oxidação. O objetivo deste trabalho é avaliar a eficácia deste composto para limpeza dos tubos e determinar a qualidade da passivação que os óxidos produzidos desta forma proporcionam para as lâminas de Si. Observou-se que as limpezas realizadas não foram capazes de prevenir a contaminação de lâminas de Si de alto tempo de vida inicial. Porém, o Trans-LC foi suficientemente eficaz para oxidações realizadas em lâminas de baixo tempo de vida dos portadores minoritários.Even though the standard film for passivation currently utilized in the silicon solar cell industry is SiNx, the late tendencies of the market make it necessary to reevaluate the SiO2 for surface passivation of solar cells. In order to grow these oxides, however, high-temperature processing steps are necessary, which leave the wafers susceptible to metallic contamination. To avoid this contamination, the organic compound Trans-LC is used to clean the oxidation tube. The goal of this work is to evaluate the efficacy of this compound for the tube cleaning and determine the passivation quality that the oxides produced this way provide to the Si wafers. It was observed that the cleanings were not capable to prevent the contamination of high initial lifetime Si wafers. However, the Trans-LC was sufficiently effective for oxidations realized on wafers with low initial minority carrier lifetime.Tema 4: Energía solar, conversión fotovoltaica.Facultad de Arquitectura y Urbanism

Análise de processos de oxidação com Trans-LC para fabricação de células solares

Apesar do filme para passivação padrão da indústria de células solares atual ser SiNx, as últimas tendências do mercado fazem com que seja necessário reavaliar o SiO2 para passivação das superfícies de células solares. Para crescer estes óxidos, no entanto, são necessárias etapas de processamento em altas temperaturas, que deixam as lâminas de silício suscetíveis a contaminações metálicas. Para evitar essa contaminação, o composto orgânico Trans-LC é utilizado para limpeza do tubo de oxidação. O objetivo deste trabalho é avaliar a eficácia deste composto para limpeza dos tubos e determinar a qualidade da passivação que os óxidos produzidos desta forma proporcionam para as lâminas de Si. Observou-se que as limpezas realizadas não foram capazes de prevenir a contaminação de lâminas de Si de alto tempo de vida inicial. Porém, o Trans-LC foi suficientemente eficaz para oxidações realizadas em lâminas de baixo tempo de vida dos portadores minoritários.Even though the standard film for passivation currently utilized in the silicon solar cell industry is SiNx, the late tendencies of the market make it necessary to reevaluate the SiO2 for surface passivation of solar cells. In order to grow these oxides, however, high-temperature processing steps are necessary, which leave the wafers susceptible to metallic contamination. To avoid this contamination, the organic compound Trans-LC is used to clean the oxidation tube. The goal of this work is to evaluate the efficacy of this compound for the tube cleaning and determine the passivation quality that the oxides produced this way provide to the Si wafers. It was observed that the cleanings were not capable to prevent the contamination of high initial lifetime Si wafers. However, the Trans-LC was sufficiently effective for oxidations realized on wafers with low initial minority carrier lifetime.Tema 4: Energía solar, conversión fotovoltaica.Facultad de Arquitectura y Urbanism

Influência do tempo de difusão de boro no campo retrodifusor seletivo de alumínio e boro em células solares de silício

O campo retrodifusor seletivo em células solares possibilita aumentar a eficiência e evita o abaulamento. O objetivo deste trabalho é analisar a influência do tempo de difusão de boro na formação do campo retrodifusor seletivo de alumínio e boro em células solares processadas em lâminas de silício Czochralski tipo p, grau solar. A difusão de boro foi implementada em toda a face posterior da lâmina e por serigrafia foi depositada a pasta de alumínio, somente nas trilhas metálicas. O processo de queima das pastas metálicas foi realizado em forno de esteira. Variou-se o tempo de difusão de boro de 10 a 30 minutos para a temperatura de difusão de 950 a 970 °C. Constatou-se que o melhor tempo de difusão depende da temperatura de difusão de boro e que a maior eficiência média, de (15,6 ± 0,1) %, foi obtida para a temperatura de 970 °C e tempo de difusão de 30 minutos.The selective back surface field in solar cells enables to increase the efficiency and avoid the bowing. The objective of this study is to analyze the influence of boron diffusion time in the formation of boron/aluminum selective back surface field. The solar cells were processed in solar grade Si-Cz wafers. The boron diffusion was performed in the whole rear face of the silicon wafer and the aluminum paste was deposited by screen printing, only in the metal fingers. The firing process of the metal pastes was performed in a belt furnace. The boron diffusion time was ranged from 10 to 30 minutes for the diffusion temperature from 950 °C to 970 °C. It was found that the better diffusion time depends on the boron diffusion temperature and the highest average efficiency of solar cells, of (15.6 ± 0.1) %, was obtained with the temperature of 970 °C and the diffusion time of 30 minutes.Tema 4: Energía solar, conversión fotovoltaica.Facultad de Arquitectura y Urbanism

Análise de processos de oxidação com Trans-LC para fabricação de células solares

Apesar do filme para passivação padrão da indústria de células solares atual ser SiNx, as últimas tendências do mercado fazem com que seja necessário reavaliar o SiO2 para passivação das superfícies de células solares. Para crescer estes óxidos, no entanto, são necessárias etapas de processamento em altas temperaturas, que deixam as lâminas de silício suscetíveis a contaminações metálicas. Para evitar essa contaminação, o composto orgânico Trans-LC é utilizado para limpeza do tubo de oxidação. O objetivo deste trabalho é avaliar a eficácia deste composto para limpeza dos tubos e determinar a qualidade da passivação que os óxidos produzidos desta forma proporcionam para as lâminas de Si. Observou-se que as limpezas realizadas não foram capazes de prevenir a contaminação de lâminas de Si de alto tempo de vida inicial. Porém, o Trans-LC foi suficientemente eficaz para oxidações realizadas em lâminas de baixo tempo de vida dos portadores minoritários.Even though the standard film for passivation currently utilized in the silicon solar cell industry is SiNx, the late tendencies of the market make it necessary to reevaluate the SiO2 for surface passivation of solar cells. In order to grow these oxides, however, high-temperature processing steps are necessary, which leave the wafers susceptible to metallic contamination. To avoid this contamination, the organic compound Trans-LC is used to clean the oxidation tube. The goal of this work is to evaluate the efficacy of this compound for the tube cleaning and determine the passivation quality that the oxides produced this way provide to the Si wafers. It was observed that the cleanings were not capable to prevent the contamination of high initial lifetime Si wafers. However, the Trans-LC was sufficiently effective for oxidations realized on wafers with low initial minority carrier lifetime.Tema 4: Energía solar, conversión fotovoltaica.Facultad de Arquitectura y Urbanism

Influência do tempo de difusão de boro no campo retrodifusor seletivo de alumínio e boro em células solares de silício

O campo retrodifusor seletivo em células solares possibilita aumentar a eficiência e evita o abaulamento. O objetivo deste trabalho é analisar a influência do tempo de difusão de boro na formação do campo retrodifusor seletivo de alumínio e boro em células solares processadas em lâminas de silício Czochralski tipo p, grau solar. A difusão de boro foi implementada em toda a face posterior da lâmina e por serigrafia foi depositada a pasta de alumínio, somente nas trilhas metálicas. O processo de queima das pastas metálicas foi realizado em forno de esteira. Variou-se o tempo de difusão de boro de 10 a 30 minutos para a temperatura de difusão de 950 a 970 °C. Constatou-se que o melhor tempo de difusão depende da temperatura de difusão de boro e que a maior eficiência média, de (15,6 ± 0,1) %, foi obtida para a temperatura de 970 °C e tempo de difusão de 30 minutos.The selective back surface field in solar cells enables to increase the efficiency and avoid the bowing. The objective of this study is to analyze the influence of boron diffusion time in the formation of boron/aluminum selective back surface field. The solar cells were processed in solar grade Si-Cz wafers. The boron diffusion was performed in the whole rear face of the silicon wafer and the aluminum paste was deposited by screen printing, only in the metal fingers. The firing process of the metal pastes was performed in a belt furnace. The boron diffusion time was ranged from 10 to 30 minutes for the diffusion temperature from 950 °C to 970 °C. It was found that the better diffusion time depends on the boron diffusion temperature and the highest average efficiency of solar cells, of (15.6 ± 0.1) %, was obtained with the temperature of 970 °C and the diffusion time of 30 minutes.Tema 4: Energía solar, conversión fotovoltaica.Facultad de Arquitectura y Urbanism

Influência do tempo de difusão de boro no campo retrodifusor seletivo de alumínio e boro em células solares de silício

O campo retrodifusor seletivo em células solares possibilita aumentar a eficiência e evita o abaulamento. O objetivo deste trabalho é analisar a influência do tempo de difusão de boro na formação do campo retrodifusor seletivo de alumínio e boro em células solares processadas em lâminas de silício Czochralski tipo p, grau solar. A difusão de boro foi implementada em toda a face posterior da lâmina e por serigrafia foi depositada a pasta de alumínio, somente nas trilhas metálicas. O processo de queima das pastas metálicas foi realizado em forno de esteira. Variou-se o tempo de difusão de boro de 10 a 30 minutos para a temperatura de difusão de 950 a 970 °C. Constatou-se que o melhor tempo de difusão depende da temperatura de difusão de boro e que a maior eficiência média, de (15,6 ± 0,1) %, foi obtida para a temperatura de 970 °C e tempo de difusão de 30 minutos.The selective back surface field in solar cells enables to increase the efficiency and avoid the bowing. The objective of this study is to analyze the influence of boron diffusion time in the formation of boron/aluminum selective back surface field. The solar cells were processed in solar grade Si-Cz wafers. The boron diffusion was performed in the whole rear face of the silicon wafer and the aluminum paste was deposited by screen printing, only in the metal fingers. The firing process of the metal pastes was performed in a belt furnace. The boron diffusion time was ranged from 10 to 30 minutes for the diffusion temperature from 950 °C to 970 °C. It was found that the better diffusion time depends on the boron diffusion temperature and the highest average efficiency of solar cells, of (15.6 ± 0.1) %, was obtained with the temperature of 970 °C and the diffusion time of 30 minutes.Tema 4: Energía solar, conversión fotovoltaica.Facultad de Arquitectura y Urbanism

Generalized stochastic Schroedinger equations for state vector collapse

A number of authors have proposed stochastic versions of the Schr\"odinger equation, either as effective evolution equations for open quantum systems or as alternative theories with an intrinsic collapse mechanism. We discuss here two directions for generalization of these equations. First, we study a general class of norm preserving stochastic evolution equations, and show that even after making several specializations, there is an infinity of possible stochastic Schr\"odinger equations for which state vector collapse is provable. Second, we explore the problem of formulating a relativistic stochastic Schr\"odinger equation, using a manifestly covariant equation for a quantum field system based on the interaction picture of Tomonaga and Schwinger. The stochastic noise term in this equation can couple to any local scalar density that commutes with the interaction energy density, and leads to collapse onto spatially localized eigenstates. However, as found in a similar model by Pearle, the equation predicts an infinite rate of energy nonconservation proportional to $\delta^3(\vec 0)$, arising from the local double commutator in the drift term.Comment: 24 pages Plain TeX. Minor changes, some new references. To appear in Journal of Physics

Genotyping-by-Sequencing and Ecological Niche Modeling Illuminate Phylogeography, Admixture, and Pleistocene Range Dynamics in Quaking Aspen (Populus Tremuloides)

Populus tremuloides is the widest‐ranging tree species in North America and an ecologically important component of mesic forest ecosystems displaced by the Pleistocene glaciations. Using phylogeographic analyses of genome‐wide SNPs (34,796 SNPs, 183 individuals) and ecological niche modeling, we inferred population structure, ploidy levels, admixture, and Pleistocene range dynamics of P. tremuloides, and tested several historical biogeographical hypotheses. We found three genetic lineages located mainly in coastal–Cascades (cluster 1), east‐slope Cascades–Sierra Nevadas–Northern Rockies (cluster 2), and U.S. Rocky Mountains through southern Canadian (cluster 3) regions of the P. tremuloides range, with tree graph relationships of the form ((cluster 1, cluster 2), cluster 3). Populations consisted mainly of diploids (86%) but also small numbers of triploids (12%) and tetraploids (1%), and ploidy did not adversely affect our genetic inferences. The main vector of admixture was from cluster 3 into cluster 2, with the admixture zone trending northwest through the Rocky Mountains along a recognized phenotypic cline (Utah to Idaho). Clusters 1 and 2 provided strong support for the “stable‐edge hypothesis” that unglaciated southwestern populations persisted in situ since the last glaciation. By contrast, despite a lack of clinal genetic variation, cluster 3 exhibited “trailing‐edge” dynamics from niche suitability predictions signifying complete northward postglacial expansion. Results were also consistent with the “inland dispersal hypothesis” predicting postglacial assembly of Pacific Northwestern forest ecosystems, but rejected the hypothesis that Pacific‐coastal populations were colonized during outburst flooding from glacial Lake Missoula. Overall, congruent patterns between our phylogeographic and ecological niche modeling results and fossil pollen data demonstrate complex mixtures of stable‐edge, refugial locations, and postglacial expansion within P. tremuloides. These findings confirm and refine previous genetic studies, while strongly supporting a distinct Pacific‐coastal genetic lineage of quaking aspen

ELPIS-JP: a dataset of local-scale daily climate change scenarios for Japan

We developed a dataset of local-scale daily climate change scenarios for Japan (called ELPIS-JP) using the stochastic weather generators (WGs) LARS-WG and, in part, WXGEN. The ELPIS-JP dataset is based on the observed (or estimated) daily weather data for seven climatic variables (daily mean, maximum and minimum temperatures; precipitation; solar radiation; relative humidity; and wind speed) at 938 sites in Japan and climate projections from the multi-model ensemble of global climate models (GCMs) used in the coupled model intercomparison project (CMIP3) and multi-model ensemble of regional climate models form the Japanese downscaling project (called S-5-3). The capability of the WGs to reproduce the statistical features of the observed data for the period 1981–2000 is assessed using several statistical tests and quantile–quantile plots. Overall performance of the WGs was good. The ELPIS-JP dataset consists of two types of daily data: (i) the transient scenarios throughout the twenty-first century using projections from 10 CMIP3 GCMs under three emission scenarios (A1B, A2 and B1) and (ii) the time-slice scenarios for the period 2081–2100 using projections from three S-5-3 regional climate models. The ELPIS-JP dataset is designed to be used in conjunction with process-based impact models (e.g. crop models) for assessment, not only the impacts of mean climate change but also the impacts of changes in climate variability, wet/dry spells and extreme events, as well as the uncertainty of future impacts associated with climate models and emission scenarios. The ELPIS-JP offers an excellent platform for probabilistic assessment of climate change impacts and potential adaptation at a local scale in Japan

KK Parity in Warped Extra Dimension

We construct models with a Kaluza-Klein (KK) parity in a five- dimensional warped geometry, in an attempt to address the little hierarchy problem present in setups with bulk Standard Model fields. The lightest KK particle (LKP) is stable and can play the role of dark matter. We consider the possibilities of gluing two identical slices of 5D AdS in either the UV (IR-UV-IR model) or the IR region (UV-IR-UV model) and discuss the model-building issues as well as phenomenological properties in both cases. In particular, we find that the UV-IR-UV model is not gravitationally stable and that additional mechanisms might be required in the IR-UV-IR model in order to address flavor issues. Collider signals of the warped KK parity are different from either the conventional warped extra dimension without KK parity, in which the new particles are not necessarily pair-produced, or the KK parity in flat universal extra dimensions, where each KK level is nearly degenerate in mass. Dark matter and collider properties of a TeV mass KK Z gauge boson as the LKP are discussed.Comment: 35 pages, 11 figure