1,721,046 research outputs found
S. Solmi, Promemoria su «La Cultura»
No full textL'articolo commenta uno scritto inedito di S. Solmi, appartenente ai suoi ultimi anni, nel quale ricostruisce le vicende editoriali del periodico "La Cultura" negli anni trenta. L'articolo cerca di valorizzare la testimonianza di Solmi per una storia della rivista
Effects of donor concentration on transient enhanced diffusion of boron in silicon
No full textThe effects of substrate donor concentration on transient enhanced diffusion (TED) of boron implanted into silicon wafers predoped with arsenic or phosphorus have been investigated by using secondary ion mass spectroscopy and theoretical simulations. Boron ions have been implanted at low energy (10–20 keV) and successively annealed in the temperature range 700–1000 °C. No detectable boron TED (TED<10×) has been observed in samples uniformly predoped with P at the concentration of 1.2×1020 cm–3. The B TED is strongly reduced even in the samples predoped with As. However, for the highest As concentration (1.3×1020 cm–3) an exponential high diffusivity tail has been detected in the B profiles at all the examined annealing temperatures. This anomalous effect has been attributed to the interstitials produced by an As clustering reaction occurring during the low temperature annealing. The main effects responsible for the vanishing of the B TED, i.e., ionization of the interstitials (Fermi level effect), competitive behavior of P in the interaction with the interstitials, and donor-acceptor pairing have been examined and discusse
The electrical activation of B in the presence of boron-interstitials clusters
No full textBoron marker-layer structures have been used to analyze the evolution of Boron-Interstitial clusters (BICs) formed during transient enhanced diffusion (TED). Our approach is based on the measure of B activation by spreading resistance profiling (SRP) after annealing of Si implantation damage. We investigated a wide range of implant conditions in terms of defect densities, ranging from a very dilute interstitial cascade up to the amorphization threshold of Si. We found a common behavior of BICs in terms of trapping and release processes of B atoms. The BICs density as a function of time for different concentration ratios of I and B has been determine
Transient enhanced diffusion of arsenic in silicon
No full textThe transient enhanced diffusion (TED) of As in silicon samples implanted at 35 keV with dose 5*1015 cm-2 has been investigated in the temperature range between 750 and 1030 °C by comparing experimental and simulated profiles. For temperatures higher than 900 °C the phenomenon is of modest entity and vanishes after a few seconds, whereas at lower temperatures diffusivity enhancements of some order of magnitude have been observed. The anomalous shift of the junction depth, evaluated at 2*1018 cm-3, is about 12 nm at 900 °C and increases up to 45 nm at 750 °C. It has been verified that the two are the contributions, that generate the interstitial excess responsible for the TED: (i) the implantation damage and (ii) the aggregation in clusters of the As atoms. From an experiment that allows us to separate the two contributions, we estimate that about one third of the TED observed in the first 20 min of annealing at 800 °C is due to the defects produced by clustering. The influence of clustering on the shape of the As profiles after diffusion at different temperatures is also discusse
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
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