1,721,061 research outputs found
Effect of UV-O-2, NF3/H-2 surface preparation on the crystalline defects in silicon homoepitaxy (Part I. A study on photochemical surface preparation in series)
No full textIn this work, the organic residue and oxide on silicon wafer were treated with UV-excited oxygen and trifluoronitrogen gases as a pro-treatment for silicon homoepitaxy. A typical positive photo resist, AZ 1512, was coated as a model organic residue. UV-O-2 cleaning (UVOC) and UV-NF3/H-2 treatment removed the organic residue and native oxide layer, respectively, for silicon epitaxial growth. A study of removal rate showed that the processing temperature is a more critical process parameter than pressure. Besides, hydrogen dilution improves the surface roughness of UV-NF3-treated surface as shown in the atomic force microscope images. (C) 2002 Published by Elsevier Science B.V.This work was supported by the Brain Korea 21 Project
Silicon epitaxial film growth on silicon substrate exposed to UV-excited NF3/H-2 gas for native oxide removal
No full textIn situ UV-excited NF3/H-2 gas phase cleaning for native oxide removal and Si epitaxial him growth experiments were carried out in a load-locked reactor equipped with a UV lamp and PEN heater. The effect of composition of NF3/H-2 and UV exposure on the etching characteristics of native oxide and thermal oxide has been studied. Main etching species were identified as F, NFx and HF. Hydrogen added to NF3 gas alleviates silicon surface pitting to result in the very smooth surface. RMS surface roughness was as low as 0.5 Angstrom at the ratio of H-2/NF3 of 3. Analysis of silicon eptaxial film showed the effectiveness of NF3/H-2 gas phase cleaning as the pretreatment process prior to silicon eptaxial him growth. (C) 1999 Published by Elsevier Science B.V. All rights reserved
Effect of CO ans CO2 addition to CF4/O2 gas system on the etch rate and selectivity of W
No full textInfluence of Lithiation on Nanomechanical Properties of Silicon Nanowires Probed with Atomic Force Microscopy
No full textThe nanomechanical properties of fully lithiated and unlithiated silicon nanowire deposited on silicon substrate have been studied with atomic force microscopy. Silicon nanowires were synthesized using the vapor-liquid-solid process on stainless steel substrates using Au catalyst. Fully lithiated silicon nanowires were obtained by using the electrochemical method, followed by drop-casting on the silicon substrate. The roughness, derived from a line profile of the surface measured in contact mode atomic force microscopy, has a smaller value for lithiated silicon nanowire and a higher value for unlithiated silicon nanowire. Force spectroscopy was utilitzed to study the influence of lithiation on the tip-surface adhesion force. Lithiated silicon nanowire revealed a smaller value than that of the Si nanowire substrate by a factor of two, while the adhesion force of the silicon nanowire is similar to that of the silicon substrate. The Young's modulus obtained from the force-distance curve, also shows that the unlithiated silicon nanowire has a relatively higher value than lithiated silicon nanowire due to the elastically soft amorphous structures. The frictional forces acting on the tip sliding on the surface of lithiated and unlithiated silicon nanowire were obtained within the range of 0.5-4.0 Hz and 0.01-200 nN for velocity and load dependency, respectively. We explain the trend of adhesion and modulus in light of the materials properties of silicon and lithiated silicon. The results suggest a useful method for chemical identification of the lithiated region during the charging and discharging process
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
Transcriptional activation of SHP by PPAR-gamma in liver
No full textThe mechanism of how PPAR gamma decrease gluconeogenic gene expressions in liver is still unclear. Since PPAR gamma is a transcriptional activator, it requires a mediator to decrease the transcription of gluconeogenic genes. Recently, SHP has been shown to mediate the bile acid-dependent down regulation of gluconeogenic gene expression in liver. This led us to explore the possibility that SHP may mediate the antigluconeogenic effect of PPAR gamma. In the present study, we have identified and characterized the presence of functional PPRE in human SHP promoter. We show the binding of PPAR gamma/RXR alpha heterodimer to the PPRE and increased SHP expression by rosiglitazone in primary rat hepatocytes. Taken together with the previous reports about the function of SHP on gluconeogenesis, our results indicate that SHP can mediate the acute antigluconeogenic effect of PPAR gamma. (C) 2007 Elsevier Inc. All rights reserved
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