1,720,961 research outputs found
Silicon heterojunction solar cells with p nanocrystalline thin emitter on monocrystalline substrate
No full textIn the framework of plasma deposition of silicon heterojunction solar cells, the issue of depositing, by VHF, a microcrystalline emitter, without affecting the passivating properties of the underlying amorphous buffer layer, is addressed. The sequence Deposition-Exposure to H2 Plasma-Deposition was used to fabricate the microcrystalline emitter. Using High Resolution Transmission Electron Microscopy, we give microscopic evidence of the long range effects of hydrogen, already inferred by large area optical techniques. Upon exposure to H2 plasma, it is observed that silicon nanocrystallites are formed within the amorphous layer. Thinner amorphous layers undergo etching, and epitaxial growth takes place from the substrate. Photovoltaic devices with open circuit voltage up to 638 mV were fabricated
Silicon heterojunction solar cells with microcrystalline emitter
No full textMicrocrystalline n-type emitters, that, compared to a-Si:H ones, ensure better electronic properties and better transparency in the visible, were used to fabricate heterojunction solar cells on crystalline silicon. The substrate surface was passivated by the deposition of a very thin intrinsic a-Si:H buffer layer. The microcrystalline n-type emitters were deposited by radio-frequency (rf) Plasma Enhanced Chemical Vapor Deposition, using a high hydrogen diluted gas mixture. The simulation of optical spectra of n/i double layers on c-Si gives a preliminary evidence that the continuity of the intrinsic a-Si:H buffer layer is preserved after the rf deposition. The photovoltaic devices incorporating microcrystalline emitters exhibit a remarkable increase of short circuit current (Jsc) and efficiency (a factor 1.24 and 1.38 respectively) compared to the case of a-Si:H emitters. Noticeable improvements are observed if the structure is applied to textured substrates
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
Wide band-gap silicon-carbon alloys deposited by very high frequency plasma enhanced chemical vapor deposition
No full textThe use of Very High Frequency (VHF) Plasma Enhanced Chemical Vapour Deposition in a capacitive discharge is investigated to fabricate hydrogenated amorphous silicon carbon alloys, using silane and methane as silicon and carbon precursors respectively and hydrogen dilution of the gas mixture. The properties of samples differ significantly from what normally observed for rf deposition. A wide band gap material is obtained, with a carbon ratio ranging from 0.2 to 0.63. An energy gap up to 3.4 eV is measured, indicating a large sp3 content. The most interesting properties are observed using 90% hydrogen dilution and 350°C as substrate temperature. In this case, a Si-C bond concentration up to 6x1022 cm-3 was measured for stoichiometric samples, associated to a highly crosslinked structure and no detectable Si-CH3 bending signal. The role of hydrogen in determining the optical properties of the film is established and is shown to affect mainly the valence electron concentration.
Basing on the free energy model, hydrogen bonding is observed to lie in between a random and chemically ordered configuration. The results are obtained at a deposition rate much larger than both rf and ECR deposition, and are associated to a limited gas consumption, both aspects being advantageous for practical applications. The large Si-C bond concentration, associated to a limited silicon and carbon hydrogenation, makes the VHF deposited a-SiC:H a good starting material for subsequent crystallisation
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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