1,720,982 research outputs found
Influence of doping elements on the formation rate of silicon nanowires by silver-assisted chemical etching
No full textMetal-assisted chemical etching (MACE) has gained great interest for the preparation of vertically aligned silicon nanowires (SiNWs); however, the process mechanism has not yet been identified. In this study, the influence of doping elements on the formation rate of SiNWs prepared by silver-assisted chemical etching was investigated. Two n-type silicon substrates, bulk silicon and silicon-on-insulator (SOI) samples, containing different dopant concentrations (from 1011 to 1019 atoms cm− 3) and species (phosphorous and arsenic), were considered. The SiNW formation rates increase with dopant concentration and are influenced by the dopant species. The use of SOI samples allowed highlighting the remarkable loss of the starting device layer in conventional process conditions, never previously observed; such occurrence limits the most achievable SiNW length. The study of the gas evolution both from bulk and SOI samples allowed for the first time the in situ H2 detection as well as to identify one definite overall process reaction
Composition/Structure Relationships in Monolithic Borophosphosilicate Glasses Obtained by the Sol-Gel Route
No full textElectron paramagnetic resonance characterization of silica-dispersed copper molybdate obtained by sol-gel and impregnation methods
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Electrically Detected Magnetic Resonance of Donors and Interfacial Defects in Silicon Nanowires
No full textWe report our work on the characterization by electrically detected magnetic resonance (EDMR) measurements of silicon nanowires (SiNWs) produced by different top-down processes. SiNWs were fabricated starting from SOI wafers using standard e-beam lithography and anisotropic wet etching or by metal-assisted chemical etching. Further oxidation was used to reduce the wire cross section. Different EDMR implementations were used to address the electronic wave function of donors (P) and to characterize point defects at the SiNWs/SiO(2) interface. The EDMR spectra of as produced SiNWs with high donor concentration ([P]= 10(18) cm(-3)) show a single line related to delocalized electrons. SiNWs produced on substrates with lower donor concentration ([P] < 10(16) cm(-3)) reveal the doublet related to substitutional P in Si, as well as lines related to interfacial defects such as Pb(0), Pb, E', and E'-like. The EDMR spectra of samples produced by metal-assisted chemical etching exposed to post production oxidation reveal a disordered and defective interface and the disappearance of the P related signal. Forming gas annealing, on the other hand, reduces the contribution of interfacial defects and allows a better resolution of the P related doublet
Silica Copper molybdate catalysts prepared by sol-gel and impregnation methods: reactivity and spectroscopic studies
No full textGoing 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
Slica-copper molybdate catalysts prepared by sol-gel and impregnation methods: reactivity and spectroscopic studies.
No full textAppropriate 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
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