1,720,987 research outputs found
Effects of the deposition temperature on the transport property, chemical composition and conduction band structure of CaRuO3-delta thin films directly grown on Si (100) substrates
No full textThe transport properties, chemical composition and energy band structure of directly integrated CaRuO3-delta thin films on a Si substrate were investigated by resistance - temperature ( R - T) measurement, x-ray photoelectron spectroscopy ( XPS) and near edge x-ray absorption fine structure ( NEXAFS) spectroscopy of oxygen K-edge. At high deposition temperatures, the metallic characteristic of CaRuO3-delta thin film is susceptible, with a clear preference for ( 1 1 0) crystallite formation, which induces delocalized charge carrier migration. At low deposition temperatures, CaRuO3-delta thin film takes on semiconductor behaviour responsible for current path localization causing weakening of Ru 4d-O 2p-Ca 3d orbital overlapping due to the imperfect crystalline growth. Even though there was different crystallite formation according to deposition temperature, the relative compositional difference of each element was negligible, which was supported by XPS and wavelength dispersive x-ray spectroscopy ( WDXS) analysis. Thus, the change in conductivity from semiconducting to metallic is caused by the fine crystallite nature of CaRuO3-delta at low deposition temperature which induces charge carrier localization by utilizing the incorporation of Ca-O bonding weakening, reducing the conduction energy bandwidth W and expansion of the local conduction energy band separation Delta
Material and Photonic Engineering on Lead Selenide Nanocrystal Films for Mid-infrared Emitter Development
No full textLead selenide (PbSe) is a IV-VI semiconductor material and is known to have a high absorption coefficient. This property comes from its narrow band gap (0.27eV) and strong interaction with light within the material. This means that it efficiently absorbs a significant amount of light relative to its thickness. The high absorption coefficient makes it a promising material also for solar cell absorbers, as it efficiently converts light into electrical current over a broad wavelength range. Research on PbSe has been ongoing for nearly a century, with continuous advancements in understanding its properties and potential applications. The full extent of its physical properties remains underutilized in practical devices. Despite significant advancements in recent technologies, there is still considerable potential for improving the performance and cost-efficiency of miniaturized MIR gas sensing systems. This thesis aims to develop a narrowband mid-infrared emitter by leveraging photonic engineering techniques applied to lead selenide (PbSe) nanocrystals. A key challenge lies in the inherently low radiative efficiency of PbSe, particularly at room temperature, where non-radiative processes, most notably Auger recombination tend to dominatecarrier dynamics. The first chapter of the thesis presents an overview of the properties of Lead Selenide (PbSe) and High Contrast Gratings (HCG) in the context of mid-infrared photodetection. It examines various PbSe growth techniques, emphasizing the relevance of the Chemical Bath Deposition method. Furthermore, it introduces a novel approach known as Oriented Attachment, underscoring its role in improving the material characteristics of PbSe. Chapter two of the thesis focused on deposition PbSe using Chemical Bath Deposition method, which allow the cost-effective and scalable fabrication of MIR photonic devices. In this study, I employed the water bath method to grow uniform PbSe nanocrystals using the Oriented Attachment technique on amorphous substrates. Different parameters were varied during the growth process and their effects were critically analysed. In chapter three, I studied about the annealing effects on PbSe sample. After annealing with nitrogen at different temperatures, photo luminesce significantly improved.Surface morphologies before and after the annealing of PbSe thin films were studied by Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD). The chapter four of this thesis explores the nanostructure design simulated using RSoft software, followed by the fabrication methods applied to lead selenide samples which includes the photolithography process. This work contributes to the goal of developing compact, cost-effective, low-power, and highly efficient on-chip MIR narrowband emitter for chemical sensing applications. This work explores methods to enhance PbSe film quality, along with the design and fabrication of photonic structures on PbSe samples, potentially improving the performance of PbSe-based MWIR sensingplatforms. Additionally, the potential future work aimed at enhancing the performance of PbSe emitters and photodetectors will be discussed in the concluding section of the thesis
PULSED LASER DEPOSITION AND OPTIMIZATION OF LSGM AND LSCF THIN FILMS FOR SOLID OXIDE FUEL CELL APPLICATIONS
No full textThe performance and durability of solid oxide fuel cells (SOFCs) are critically governed by the structural and chemical coherency of the hetero-interfaces between oxygen ion-conducting electrolytes and electronically conducting electrodes. In particular, realizing coherent and chemically stable interfaces between La₀.₈Sr₀.₂Ga₀.₈Mg₀.₂O₃−δ (LSGM), a fast oxygen-ion conductor, and (La₀.₆Sr₀.₄)₀.₉₅Co₀.₂Fe₀.₈O₃−δ (LSCF), a mixed ionic-electronic conductor, is critical for minimizing interfacial resistance and enabling high-efficiency energy conversion.A major challenge in solid-state fuel cells arises from the potential interdiffusion of cations across electrolyte/electrode interfaces, which can lead to the formation of undesired secondary phases and degraded ionic/electronic transport properties. Therefore, precise interface engineering is essential to preserve the functional stability of both layers. Despite the technological importance, detailed experimental studies remain lacking, especially on the epitaxial growth and hetero-interface structure of LSGM and LSCF heterostructures using Pulsed Laser Deposition (PLD). In this work, we systematically optimized PLD growth conditions for single-crystalline LSGM and LSCF thin films on SrTiO₃ (001) substrates, aiming to establish a coherent and well-defined hetero-interface suitable for fundamental studies of interfacial phenomena under the fuel cell operating condition. X-ray diffraction (XRD) analysis revealed that LSGM films grown at 800 °C and 150 mTorr of oxygen partial pressure exhibited a lattice parameter of 3.909 Å (0.017) with a full-width-at-half-maximum (FWHM) of 0.169°, while LSCF films grown under optimized conditions showed a lattice parameter of 3.916 Å (0.021) and an FWHM of 0.072°, indicating high crystallinity and epitaxial alignment. As a result, the successful fabrication of LSGM/LSCF heterostructure exhibited distinct XRD peaks from both layers, suggesting layered epitaxial growth without significant interdiffusion or secondary phase formation under the optimized conditions. This study provides a reproducible route for the coherent integration of LSGM electrolytes and LSCF electrodes via PLD, offering a model platform for exploring interfacial transport, defect chemistry, and long-term stability — essential aspects for the development of next-generation, high-performance SOFC devices
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
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
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