1,720,963 research outputs found
An analysis of a "dead layer" in the emitter of n<sup>+</sup>pp<sup>+ </sup>solar cells
No full textIn this paper, the results obtained from fabrication and characterizations of n+pp+ solar cells are presented. The existence of a dead layer in the emitter was inferred regarding to the poor quantum efficiency of the cells under short wavelength region. The effects of this layer on the solar cell performance have been analyzed using the theoretical model and demonstrated in the term of low collection efficiency near the top surface of the emitter and high front surface recombination velocity
A new masking technology for deep glass etching and its microfluidic application
No full textA new masking technology for wet etching of glass, to a depth of more than 300µm, is reported. Various mask materials, which can be patterned by standard photolithography and metal etching processes, were investigated for glass etching in concentrated hydrofluoric acid (HF). A multilayer of metal, Cr/Au/Cr/Au, in combination with thick SPR220-7 photoresist, was found to be ideal for this purpose. Through holes etched from both sides of a 500µm thick Pyrex glass wafer were obtained. Pinholes, created in the glass by failure of simple metal masking when subjected to HF etching, were successfully eliminated using the new masking technology. In addition, the lateral undercutting of glass caused by the under-etching of the Cr mask was minimized to 27% of the etching depth. With these advantages, this newly developed masking method was successfully applied to fabricate microfluidic components for a micro-peristaltic pump to be integrated in a micro polymerase chain reaction (PCR) device. These components include through holes for liquid accessing and electrical contacting and a 200µm thick pump diaphragm. This new masking technology also adds to the methods available to fabricate the microfluidic devices in glass substrates
Third order Bragg grating filters in small SOI waveguides
No full textThird order grating filters fabricated in small Silicon-on-Insulator rib waveguides are demonstrated. Variations in grating etch depth and duty cycle are considered, and a maximum experimental reflection of 42% is demonstrated for gratings of 1500 µm in length, with a grating period of approximately 689nm and an etch depth of 200nm. Agreement with modeling is shown to be good
Characterisation of PZT thin film micro-actuators using a silicon micro-force sensor
Full text linkThis paper reports on the measurements of displacement and blocking force of piezoelectric micro-cantilevers. The free displacement was studied using a surface profiler and a laser vibrometer. The experimental data were compared with an analytical model which showed that the PZT thin film has a Young's modulus of 110 GPa and a piezoelectric coefficient d31,f of 30 pC/N. The blocking force was investigated by means of a micro-machined silicon force sensor based on the silicon piezoresistive effect. The generated force was detected by measuring a change in voltage within a piezoresistors bridge. The sensor was calibrated using a commercial nano-indenter as a force and displacement standard. Application of the method showed that a 700 μm long micro-cantilever showed a maximum displacement of 800 nm and a blocking force of 0.1 mN at an actuation voltage of 5 V, within experimental error of the theoretical predictions based on the known piezoelectric and elastic properties of the PZT film
Fabrication of improved piezoresistive silicon cantilever probe for the atomic force microscope
No full textThis paper describes an improved design for a monolithic silicon atomic force microscope (AFM) probe using piezoresistive sensing. The probe is V shaped, with a sharp tip at the free end and two piezoresistors at the root, and is fabricated using silicon-on-insulator (SOI) starting material. The maximum sensitivity of the AFM probe is measured to be 4.0(± 0.1) × 10-7 Å-1, which is larger than that of the previous parallel-arm piezoresistive AFM probe. The measured results are in reasonable agreement with the values predicted by theory. The minimum detectable force and minimum detectable deflection of the AFM probes are predicted to be 1.0 × 10-10 N and 0.29 Å r.m.s., respectively, using a Wheatstone bridge arrangement biased at a voltage of ± 5 V and bandwidth of 10 Hz – 1kHz
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
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