1,721,003 research outputs found
Electrical characterization of nanostructures
No full textIn this chapter we will describe a selection of electrical characterization methods based on electrical and optical excitation of carriers.
Current-voltage and capacitance-voltage characterization investigate the mechanisms of charge transport and distribution, but a deep insight about the electrically active defect population and their properties is obtained by spectroscopic methods (thermal and photo-induced spectroscopy).
While the majority of the presented methods are widely assessed in heterostructure investigation, their successful application to nanostructures is currently at the state of the art level, as shown in the case studies on GaN nanowires
Defect characterization in GaN: Possible influence of dislocations in the yellow-band features
No full textElectric field distribution in irradiated silicon detectors
No full textParticle irradiation causes dramatic changes in bulk properties of p (+)-n-n(+) silicon structures operating as particle detectors. Several attempts to model and justify such variations have been proposed in the last few years. The main unsolved problem remains in the determination of the electric field and depletion layer distributions as key-parameters to estimate the collection efficiency of the detector. By using optical beam induced current (OBIC) and surface potential (SP) measurements we determined the behavior of the electric field and confirmed the existence of a double-junction structure appearing after irradiation. (C) 2002 Elsevier Science B.V. All rights reserved
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
Charge carrier recombination and generation analysis in materials and devices by electron and optical beam microscopy
No full textElectron beam induced current (EBIC) and optical beam induced current (OBIC) methods of scanning
microscopy are here described in view of their applications in the analysis of recombination and generation
of carriers in devices and materials. These analyses allow to evidence peculiarities in the charge carriers
transport and/or failure in devices charge collection, measuring electrical parameters in the
micrometer range, such as potential distribution within the sample, diffusion length and surface recombination
velocity. This review will illustrate some case studies relevant to devices and material investigations
in the two geometrical configurations: normal and planar. Literature results are reviewed in
order to show capabilities and effectiveness of these methods in the investigation of the defect electrical
activity and resulting localized minority carrier recombination and generation in devices under operating
conditions, as well as in native semiconductor materials such as silicon, gallium arsenide and gallium
nitride
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
Double-junction effect in proton-irradiated silicon diodes
No full textThis article concerns the existence of a double-junction effect in proton-irradiated silicon p(+)-nu-n(+) (pin) diodes demonstrated by surface potential and optical-beam-induced current (OBIC) investigations. By increasing the diode biasing, the junctions existing at both ends in the irradiated devices move towards each other up to join, hence, causing a full depletion of the diodes. Due to the inhomogeneity of the electric field, however, the charge-carrier collection is strongly dependent on the position. The extent of the diode depletion layers at both ends and the shape of the electric field within the p(+)-nu-n(+) diodes are determined as a function of the bias applied. Three-dimensional photocurrent maps obtained by OBIC profiles allow for imaging the double junction. The deep level analysis evidences the presence of irradiation-induced defects, which are responsible for the double-junction effect
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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