1,721,030 research outputs found
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
Atomic layer deposition : from reaction mechanisms to 3D-integrated micro-batteries
Get PDFOne major difficulty in maintaining the size reduction in electronic devices is the controlled deposition of high-quality thin films with the right film properties. Besides this trend of miniaturization in information processing technology, i.e., the "More-Moore" trend, there has been another trend for non-digital technology which is designated as "More-than-Moore". "More-than-Moore" is the trend towards diversification within electronic devices, in which multiple functionalities are integrated into a single unit of the device. All-solid-state 3D-integrated micro-batteries are a good example of the More-than-Moore approach as they integrate energy storage, which is a traditionally macroscopic non-semiconductor technology, into a chip-size unit using techniques compatible with semiconductor technology. In all-solid-state 3D-integrated microbatteries, the various battery materials have to be deposited as thin films. Furthermore, to achieve a high capacity per footprint area on the chip surface, the thin films have to be deposited in high-aspect-ratio structures etched in the Si substrate. Controlled deposition of high-quality films with the right film properties is therefore also a challenge in this research field. A thin-film deposition technique which typically exhibits a high material quality, a high uniformity, precise growth control, and an excellent conformality is atomic layer deposition (ALD). ALD has the potential to be an enabling technology for a wide range of applications. To be able to develop new ALD processes and materials, detailed understanding of the reaction mechanisms and the ALD process itself are essential. Besides the conventional thermallydriven ALD processes, the usage of energy-enhanced methods is considered, i.e., plasma-assisted and ozone-based processes. Plasma-assisted ALD can for instance facilitate deposition of conductive films. Furthermore, oxygen plasma and ozone gas are well-suited to grow oxide thin films even at low substrate temperatures. The reactive reactants used can, however, recombine at surfaces which could complicate deposition in 3D structures. In this thesis new energy-enhanced ALD processes are developed and further understanding is obtaned on their reaction mechanisms. Also the ability of energy-enhanced ALD processes to conformally coat 3D structures is investigated. Moreover, the application of ALD in energy technologies is further explored by focussing on solid-state 3D-integrated batteries. The use of ALD in Li-ion battery synthesis is relatively unexplored and therefore the potential of ALD for Li-ion batteries is reviewed in this work. Not only the More-than-Moore application of all-solid-state 3D-integrated microbatteries is considered, but also larger-scale Li-ion battery concepts that can benefit from ALD as well. Nanostructuring is targeted as a solution to achieve the improvements required for implementing batteries in a wide range of applications. The potential of ALD is discussed for three battery concepts that can be distinguished, i.e., particle-based electrodes, 3D-structured electrodes, and 3D solid-state micro-batteries. It is discussed that a large range of materials can be deposited by ALD and recent demonstrations of improvements in battery technology by ALD are used to exemplify its large potential. Conformal deposition of conductive materials is needed in a variety of More-than-Moore applications, e.g., for electrodes and current collectors. TiN and TaN deposited by plasma-assisted ALD were demonstrated to serve as Li barrier and anode current collector for micro-batteries and also as Cu diffusion barrier in advanced interconnect technology for 3D-integration. Furthermore, conformal deposition of TiN films by plasma-assisted ALD was demonstrated. For some electrodes, such as the cathode current collector, a highly-chemically-stable conductive material is needed. A plasma-assisted ALD process was developed for the deposition of Pt films with excellent material properties in terms of density and resistivity. By using an additional H2-gas reduction-step, the deposition of Pt at low temperatures with good material properties was achieved, which can be of interest for deposition of Pt on plastics. Furthermore, using longer plasma exposure times, PtO2 could be deposited which is difficult to obtain by ALD. Using mass spectrometry, the reaction mechanism of plasma-assisted ALD of TaNx was investigated. For this process the reaction products released from the surface during the plasma step were found to interact with the plasma. Furthermore, the material properties of TaNx are influenced to a large extent by this interaction. Interaction of ALD reaction products with the plasma is expected to be of general significance for plasma-assisted ALD processes. The reaction products of the thermal ALD process for Pt were quantified using insitu gas-phase infrared spectroscopy and a reaction mechanism was proposed. The film growth was found to be ruled by the surface coverage of dissociatively chemisorbed oxygen with which the precursor molecules interact. The capability of plasma-assisted ALD to deposit in 3D structures was investigated using Monte Carlo simulations. It was found that deposition in 3D structures can be classified in three regimes: i.e., reaction-limited, diffusionlimited, and recombination-limited. For low values of the recombination probability, or, conformal deposition in high-aspect-ratio structures can still be achieved, as also experimentally observed for several metal oxides. For high values of the recombination probability, r, as appears to be the case for many metals, achieving a reasonable conformality becomes challenging, especially for aspect ratios >10. Sufficient conformal deposition was demonstrated for both the TiN and the Pt plasma-assisted ALD processes. For the medium aspect ratios targeted for the Li-ion micro-batteries, plasma-assisted ALD should be able to conformally deposit all materials. Similarly the loss of O3 in 3D structures was investigated where the loss of O3 on several materials was tested. To determine O3 recombination probabilities over a wide range, a method was developed using high-aspect-ratio capillaries at the inlet to a mass spectrometer. O3 typically has higher loss on materials such as MnOx and Co3O4, which can also be considered as battery materials. Several material systems were investigated and a considerable amount of fundamental understanding in ALD was generated. In particular, understanding of energy-enhanced ALD processes and understanding of their ability to coat 3D structures conformally are essential for many new application fields in which these techniques will be required
ALD, ALE and 2D Materials: atomic scale processing for optoelectronics applications
Get PDFMany applications are seeing a trend towards miniaturization and utilization of nanoscale effects. In this presentation atomic-scale processing techniques offered by Oxford Instruments will be discussed and possible benefits for optoelectronics applications are highlighted
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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