1,721,018 research outputs found
Electrical Properties of ITO/Crystalline-Silicon Contact at Different Deposition Temperatures
No full textIn this letter, the effect of deposition temperature on the barrier height between indium tin oxide (ITO) and crystalline silicon (c-Si) is presented. ITO films have been deposited by RF magnetron sputtering in the range between room temperature and 200 degrees C on both p-and n-type doped c-Si substrates. From current-voltage and capacitance-voltage characteristics of the ITO/c-Si junctions, we found that ITO deposited on 1-Omega . cm n-type doped silicon forms a rectifying junction with barrier heights varying from 0.9 to 0.3 eV, while at room temperature, an ohmic behavior on 1-Omega . cm p-type c-Si is obtained
Built-in Enhancement in a-Si:H Solar Cell by Chromium Silicide Layer
No full textTo increase the performances of amorphous silicon n-i-p solar cell, we investigate the possibility to enhance the built-in potential inserting thin high-conductivity chromium silicide layers at interfaces between metal electrodes and doped regions. We found that chromium silicide, formed on top of amorphous doped layer during chromium film evaporation, allows a reduction of activation energy of about 0.225 eV for n- and p-doped amorphous films. The activation energy reduction contributes to both built-in and open-circuit voltage enhancements, as demonstrated by comparing simulated and measured photovoltaic performances of n-i-p amorphous silicon solar cell with and without the chromium silicide layers
Wide energy band gap materials for next generation heterojunction solar cells
Full text linkDue to the increase of energy demand and the growth of atmospheric pollution, in the last few years renewable energy sources had a large growth. Among these, photovoltaic solar cells played a central role, thanks to the reduction of their cost partially due to the wide research developed on them. Currently, silicon crystalline solar cells’ state of the art is based on heterojunction structures that combines crystalline silicon with a wider band gap semiconductor material like hydrogenate amorphous silicon (a-Si:H). This technology detains current efficiency record of 26.7 %.
However, this structure has still certain aspects that can be improved such as the high light absorption of the amorphous silicon layers (a-Si:H), which limits the overall energy that can be converted into current, and their low thermal stability, which does not allow to overcome their deposition temperature (typically 200°C) in the following fabrication steps, limiting and making more difficult and costly their fabrication. Furthermore, during the amorphous silicon layers’ deposition, some highly hazardous and toxic gases are used and it would be desired to find an alternative.
In this work are studied two new materials that can help to overcome the aforementioned drawbacks of amorphous silicon layers. The first material is hydrogenated amorphous Silicon sub-Oxide (a-SiOx:H) which during this work was demonstrated to be more transparent and more thermally stable than a-Si:H, preserving the passivation properties of amorphous silicon layers. Different heterojunction solar cells based both on a-SiOx:H and a-Si:H were made and characterized, confirming the higher transparency and thermal stability of the former set with respect to the latter group. Furthermore it was proved the compatibility between deposition process of a-SiOx:H and a-Si:H, confirming this material as a suitable candidate to replace amorphous silicon layers in industry. Moreover, thanks to the oxygen presence inside the film, the a-SiOx:H layers showed a high chemically compatibility with metal oxides which, may be suitable to replace a-Si:H layers as selective contacts in case they have a high work function. Among these metal oxides it was chosen non-stoichiometric Molybdenum Oxide (MoOx) as a second material to be investigated, since unlike doped a-Si:H layer does not need the use of hazardous and toxic gases during the deposition process. MoOx layer was investigated in terms of material analysis and its characteristics and was developed together with a-SiOx:H layer to obtain high transparency and stability at industrial level. Hence the MoOx layer was successfully experimented in combination with a-SiOx:H buffer inside a complete heterojunction solar cell which was described and characterized, exploiting their high overall transparency allowing the absorption of a wider portion of sunlight spectrum in comparison to heterojunction solar cells based on a-Si:H layers.
The experimental work of my Ph.D. thesis has been mainly carried out at the “ENEA Casaccia” laboratories, some experiments have been performed at “ENEA Portici” laboratories
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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