1,720,968 research outputs found
Light sensitivity of gate lag and current DLTS as a tool to investigate the origin of dc-to-RF dispersion effects in GaAs heterostructure FETs
No full textThe light sensitivity of gate-lag transients and current-DLTS signals is experimentally analyzed in AlGaAs-GaAs HFETs and reproduced by 2D device simulations attributing the observed behaviors to the hole-trap performance of surface deep levels
Experimental/numerical investigation of the physical mechanisms behind dc-to-RF dispersion effects in GaAs-based HFET’s
No full textA consistent set of experimental and numerical results are presented, addressing to dc-to-RF dispersion effects in AlGaAs-GaAs heterostructure FET's (HFET's). Results are presented from gate-lag, transconductance (gm) frequency dispersion and current deep level transient spectroscopy (I-DLTS) experiments, allowing consistent indications about energy and location of deep-level traps to be inferred. Experimental data are fully explained by numerical device simulations, pointing out that surface traps act differently from conventionally assumed, i.e. behave as hole traps interacting with holes attracted at the ungated surface by negatively-ionized levels and consequent band bending
Light sensitivity of current DLTS and its implications on the physics of DC-to-RF dispersion in AlGaAs-GaAs HFETs
No full textThe light sensitivity of current deep-level transient spectroscopy (I-DLTS) is analyzed with the aim of gaining insight about the physics of surface-trap related dc-to-RF dispersion effects in AlGaAs-GaAs heterostructure field-effect transistors. I-DLTS experiments under dark reveals three surface-trap levels with activation energies 0.44 eV (h1), 0.59 eV (h2), and 0.85 eV (W), as well as a bulk trap with activation energy 0.45 eV (e1). While the I-DLTS signal peaks associated with the two shallower surface traps h1 and h2 are suppressed by optical illumination with energy larger than the AlGaAs bandgap, that which is associated with the deepest surface trap h3 is nearly unaffected by light up to the highest intensity adopted. Two-dimensional device simulations assuming that surface traps behave as hole traps provide an interpretation for the observed different light sensitivity of surface traps, explaining it as the result of the temperature dependence of surface hole concentration and negative trap-charge density, making trap-charge modulation at increasing temperature less and less sensitive to excess carriers generated by light
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
Energetic and spatial localisation of deep-level traps responsible for DC-to-RF dispersion effects in AlGaAs-GaAs HFETs
No full textResults are presented from gate-lag, transconductance (g(m)) frequency dispersion and current deep level transient spectroscopy (I-DLTS) experiments, allowing consistent indications about energy, location, and physical behaviour of deep-level traps in AlGaAs-GaAs hetero-structure field-effect transistors (HFETs) to be inferred. Traps responsible for DC-to-RF dispersion effects at operational temperatures are in particular localised and characterised
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
- …
