1,720,980 research outputs found
Ultra-Short Pulses Improving Performance and Reliability in Flash memories2006 21st IEEE Non-Volatile Semiconductor Memory Workshop
No full textData retention after heavy ion exposure of Floating Gate memories: analysis and simulation
No full textFloating Gate (FG) memories are the most important of nowadays nonvolatile memory technologies. We are investigating the long-term retention issues in advanced Flash memory technologies submitted to heavy ion irradiation. Long tails appears in threshold voltage distribution of cells hit by ions after they have been reprogrammed. This phenomenon is more pronounced in devices with smaller gate area. Results are explained by a new physics-based model of the leakage current flowing through the damaged oxides of FG memory cells. The model calculates the trap assisted tunneling current through a statistically distributed set of defects by using electron coupling to oxide phonons. The model is used to fit experimental data and to discuss retention properties after heavy ions exposure of future devices, featuring thinner tunnel oxide
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Radiation effects on floating-gate memory cells
No full textWe have addressed the problem of threshold voltage (VTH) variation in Flash memory cells after heavy ion irradiation by using specially designed array structures and test instruments. After irradiation, low VTH tails appear in VTH distributions, growing with ion LET and fluence. In particular, high LET ions, such as Iodine used in this work, can produce a bit flip. Since the existing models cannot account for large charge losses from the Floating Gate, we propose a new mechanism, based on the excess of positive charge produced by a single ion, temporarily lowering the tunnel oxide barrier (Positive charge Assisted Leakage Current, PALC) and enhancing the tunneling current. This mechanism fully explains experimental data we presen
Monte-Carlo Simulations of Flash Memory Array Retention
No full textOne of the major scalability limitations of flash memories is anomalous SILC, which strongly endangers device reliability and data retention. Therefore, an accurate evaluation of SILC statistics on large arrays is crucial for reliability predictions and new Flash technology development. In the last years, oxide leakage currents were deeply investigated and modeled, neglecting SILC statistics and effects on large Flash arrays. More recently, analytical models relating Flash statistical threshold voltage (VT) distributions to defect statistics and leakage current were proposed. However, these models rely on several simplifying assumptions such as the equivalent cell concept and an uniform defect population. Still, these models do not account for the initial VT distribution and neglect the role played by trap energy and effective field. In this scenario, the purpose of this paper is to present a Monte-Carlo (MC) simulator reproducing flash VT distribution, which overcomes the above model limitations. We will show that this model can be used to 1) investigate effects of defect features and technology parameters on VT distribution, and 2) analyze the impact of temperature and voltage accelerated stresses on final VT distribution
Drain-accelerated degradation of tunnel oxides in Flash memories
No full textA new technique for separating the oxide damage due to program/erase (P/E) cycling and of parasitic hot-hole injection due to bitline biasing in Flash memories is presented. The technique is based on an analysis of the spatial distribution of anomalous tail cells in the array subjected to P/E cycling. We show that electron and hole injection have different dependences on the number of P/E cycles, with the latter becoming the dominating mechanism for large cyclin
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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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