1,721,362 research outputs found
Modeling and Characterization of Metal/SiC Interface for Power Device Application
Full text linkSilicon carbide is a wide band-gap semiconductor widely considered
to be an excellent material for the fabrication of power devices
able to operate in extreme environmental conditions. Its superior
properties such as wide energy bandgap, high hardness, chemical
inertness, high electrical field breakdown strength and high thermal
conductivity enable electronic devices, based on it, to operate at
high temperatures, high voltages and high frequencies and make it
an attractive semiconducting material for the power electronics industry.
Since 1999 a number of electronic devices based on silicon
carbide are commercially available such as Schottky barrier diodes
with voltage rating of 300 - 1700 V (as of 2011) which often show
non-ideal electrical behavior.
Non-ideal electrical behavior is manifested in the abnormal current-voltage characteristics and greater than unity ideality factors.
Various theories exist as to the origin of these non-idealities some attribute
them to different conduction mechanisms such as generation-recombination
and edge-related currents and others to the inhomogeneous
Schottky barrier. We have considered the approach,
taken by Tung, which can explain all the non-ideal behaviors with
thermionic emission theory alone by assuming the Schottky barrier
height to be inhomogeneous. Inhomogeneous Schottky barrier implies
spatially varying isolated low barrier height regions existing
alongside a homogeneous high Schottky barrier. These regions are
supposed to interact, in case of being situated together, resulting in
the region with low barrier height to be pinched-off. If the pinch-off
occurs the low barrier height region (or patch depending on the
shape) has a Schottky barrier height equal to the 'saddle point potential'
in front of that patch or low barrier region. Whole Schottky
barrier is assumed to be composed of numerous such low barrier
height patches. These patches are considered to be embedded into
the high background Schottky barrier and define the overall current
transport through the Schottky barrier diode. A similar model is
the parallel conduction model presented by D. Defives et al. which
instead of considering the Schottky barrier to be composed of various
small patches, divides the Schottky barrier into two major parts
each with different Schottky barrier height and both existing simultaneously
within one Schottky barrier diode. Though accurate to
some extent, this model considers the two Schottky barrier heights
to be electrically independent of each other; which is not true in all situations. After applying Tung's theoretical model it was possible
to extract nearly correct value of Richardson constant for the Schottky
diodes with titanium and molybdenum Schottky contacts on 4H
silicon carbide. It was also possible to fit the experimental data correctly
with Tung's theoretical model. Note: The diodes used in this
research work were fabricated during a research project involving
Vishay and Politecnico di Torino
The effect of Rice husk ash (RHA) additions on corrosion of steel in OPC mortars in chloride environments
No full textThe effect of rice husk ash (RHA) addition on the corrosion of steel in ordinary Portland cement (OPC) mortars was studied. RHA was prepared from the rice husk that is a waste material in the rice producing countries. The rice husk was fired at 500 °C for 5 hours. The XRD analyses of the ash shows it to be amorphous silica (87%) with a blain specific gravity of 2.57
Modeling, Simulations and Property Parameter Sensitivity Analysis of Carbon Dioxide Capture Process
No full text
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
Fabrication of Ni/Ti/Al Schottky contact to n-type 4H-SiC under various annealing conditions
Full text linkForward I-V characteristics of a silicon carbide Schottky diode, with triple layer metallization Ni/Ti/Al as Schottky contact, are presented. Effects of different annealing conditions on the Schottky barrier height and ideality factor are discussed. The diodes were annealed in inert Ar atmosphere for 30 minutes at temperatures ranging from 600 °C to 800 °C. The ideality factors of the four diodes, chosen out of 20 diodes, range from 1.02 to 1.13 and the Schottky barrier heights range from 1.47 eV to 3.17 e
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