1,720,986 research outputs found
Amorphous silicon photodectors for optical inegrated cicuits
No full textThe first successful attempt to integrate on-chip optical waveguides based on oxidized porous silicon and amorphous silicon photodetectors have been demonstrated. Buried channel waveguides were performed by thermal oxidation of porous silicon. Amorphous silicon photodetectors were fabricated on the waveguides. Different device structures as well as their performance attributes are exhibited. The devices were demonstrated to have photocurrent characteristics promising for optoelectronic applications
Oxidized porous silicon waveguides losses
No full textThe Oxidized Porous Silicon Waveguides (OPSWG) present the chance to realize waveguide in the visible range compatible with integrated circuit (IC) fabrication technology. In OPSWG the light is confined in dense silica surrounded by a buffer of porous oxidized silicon. In this paper some of the results of the European project OLSI N degrees 28.934 are discussed. The waveguides were fabricated using p-doped (100) and n-doped (100) and (111) silicon wafers to investigate the influence of the doping type and of silicon crystal orientation on the guiding properties and the thickness of the buffer layer was varied from 1 mum to 2.5 mum changing the anodization regimes and the propagation losses were measured. Two different topology of mask have been used to determine propagation and planar bending losses. Buried OPSWG. realized depositing one micron poly-silicon layer on top of waveguides, have been thermally treated and measurements have not shown a great difference in terms of propagation losses with surface OPSWG
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No full textOpto-electronics Silicon On Insulator integrated circuits by porous silicon technology
No full textThis work reports on the CMOS-SOI devices based on porous silicon technology (PST) opening the possibility of wafer scale integration realizing on-chip optoelectronic integrated circuits by the PST. Silicon On Insulator (SOI) structure based on the preferential anodization of n+ layer within n-/n+/n- were realized. Standard n-type Si (100) have been used as initial substrates. N+ layer have been formed by Sb ion implantation into the front and backside of the substrates followed by annealing. Then an epitaxial layer has been grown on the front of the wafers and projection photolithography using reactive ion etching of both the mask and the epitaxial layer has been used to define three dimensional pattern of islands wherein device components are formed. Characteristics and device layout are presented for partially depleted devices used to build ring oscillator showing that a 1.2 micron resolution in SOI porous silicon technology is comparable with a 0.5 micron CMOS technology
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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