1,720,973 research outputs found
Electrical properties of heavily doped μc-Si:H
No full textWe have investigated the conduction in heavily doped μc‐Si:H samples grown by glow discharge by measuring the conductivity and the Hall coefficient in a wide temperature range. We show that the conductivity of these materials cannot be satisfactorily interpreted using the models already present in the literature. We put forward a model in which the material is considered composed of small crystalline grains embedded in an amorphous tissue and in which potential barriers exist between adjacent grains due to the band discontinuities. A comparison between detailed calculations and transport data shows that the tunneling (probably aided by the presence of localized states) is the fundamental conduction mechanism
A critical assessment of different models of the metastability in a-Si:H.
No full textWe have studied the light degradation and the thermal annealing of a-Si:H at different light intensities and temperatures monitoring both the defect density and the photoconductivity. This large set of data is used as a benchmark for the models of the metastability in a-Si:H. We show that an entire class of these models (which predict stretched exponential kinetics) is not in good agreement with our data. We discuss the mathematical and physical basis of these models pointing out some weak points that could explain these failures. The data are in better agreement with the “recombination induced bond breaking" models if an accurate description of annealing processes is included. The annealing rate must be computed considering a broad distribution of energy barriers. It must be also taken into account that the energy barrier for the annealing of a metastable defect can be reduced by a monomolecular trapping event at the defect itself. Our calculations show that this reduction amounts to an energy of about half the gap and lasts for a time of the order of 1 ps
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
Evaluation of Hydrogen plasma effect in a-Si:H/c-Si interface by means of Surface Photovoltage measurement and FTIR spectroscopy
No full textThe amorphous/crystalline silicon technology has demonstrated its potentiality leading to high efficiency solar cells. To enhance the interface quality we investigate the effect of hydrogen plasma and thermal annealing treatments performed on thin amorphous silicon layer deposited over crystalline silicon surface. To this aim we use surface photovoltage technique, as a contact-less tool for the evaluation of the energetic distribution of the state density at amorphous/crystalline silicon interface, and FTIR spectroscopy of the same samples to evaluate the evolution of Si-H and Si-H2 bonds. The surface photovoltage technique results to be very sensitive to the different experimental treatments, and therefore it can be considered a precious tool to monitor and improve the interface electronic quality. We found that thermal annealing produces a metastable state which goes back to the initial state after just 48 hours, while the effect of hydrogen plasma post-treatment results more stable. In particular the latter reduces the defect density of one order of magnitude and keeps constant also after one month. The hydrogen plasma is able to reduce the defect density but at the same time increases the surface charge within the a-Si:H film due to the H+ ions accumulated during the plasma exposure, leading to a more stable configuration
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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