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Channeling Effects In High-energy Implantation of N+ In Silicon
No full textNitrogen implantation of Si single crystals in the 600 keV to 1.4 MeV energy range in random, and alignment conditions on cut silicon wafers was performed. The 6 x 10(13) - 2 x 10(16) cm-2 fluence range was investigated. The beam alignment along the various axial directions was precisely checked by monitoring the backscattered nitrogen signal. RBS-channeling analysis was performed in order to measure the damage profiles. The nitrogen concentration profiles were analyzed by SIMS in all the implanted samples. The behaviour of the channeled component and the amorphization process was studied as a function of the dose for all the implantation orientations. The energy loss of the channeled ions was also estimated
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
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
Implants of Aluminum In the 50-120 Mev Energy-range Into Silicon
No full textAl ions in the 50-120 MeV energy range were implanted in Si substrates for fluences varying between 1 x 10(14) and 3.5 x 10(15) /cm2. The electrical and chemical Al distributions were obtained by spreading resistance profilometry and secondary ion mass spectroscopy and the two principal moments, R(p) and DELTAR(p), were measured. On low resistivity samples, rho = 0.01 OMEGA cm, the disorder profile induced by the 100 MeV Al implant was determined from the electrical measurement of the inactivated bulk dopant (boron) distribution. The diffusion coefficient of Al implanted into floating-zone silicon was extracted from the electrical profiles after thermal treatments in the 1000-1290-degrees-C temperature range with the result D = 7.4 exp[-3.42(eV)/kT](cm2/s)
Measurements and Applications of High-energy Boron Implants In Silicon
No full textBoron ions were implanted into high resistivity Si wafers at energies in the 15-50 MeV range and doses in the 10(11)-10(16) cm-2 range. The distribution of the implanted ions was analyzed by spreading resistance profilometry and for the high fluences by secondary ion mass spectrometry. Some samples were implanted with the beam normal to the wafer surface to study the channeling effect in a pure electronic stopping power regime of slowing down. The experimental measurements of the projected ranges and of the stragglings are compared with calculations based on the usual LSS and Bethe-Bloch formulas for the stopping power. This classic approach justifies quantitatively the distribution for the samples implanted in a random direction. The I-V characteristic of a diode performed by multiple energy boron implants of 15, 22 and 50 MeV is presented. The obtained breakdown voltage, 5 x 10(3) V, represents a possible application of the high energy implants
Axial Channeling of Boron Ions Into Silicon
No full textChanneling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5 x 10(11) and 1 x 10(15) atoms/cm2 . The axial channeling concentration profiles of implanted B+ were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, S(e), was extracted from the experimental maximum ranges for the [100] and [110] axis. The energy dependence of the electronic stopping power is given by S(e) = KE(p) with p[100] = 0.469 +/- 0.010 and p[110] = 0.554 + 0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles
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