1,721,013 research outputs found
Novel devices and methods for quantum resistance and impedance metrology
Full text linkL'abstract è presente nell'allegato / the abstract is in the attachmen
Ottimizzazione del processo di produzione e di caratterizzazione elettrica di dispositivi in grafene
No full textL'obiettivo di questo report è di riassumere i recenti sviluppi che la produzione di dispositivi in grafene ha avuto all'interno dei laboratori INRiM. Lo studio è stato effettuato su grafene di origine commerciale realizzato attraverso la tecnica della Chemical Vapor Deposition (CVD) su rame e poi successivamente trasferito su un supporto isolante (SiO2). Migliorando alcuni aspetti del processo è stato osservato , per la prima volta in istituto su grafene da CVD su rame, il punto di inversione di portatori di carica in dispositivi prodotti nei laboratori del QR e in Nanofacility. Il processo ottimizzato è stato poi testato preliminarmente (i risultati infatti non saranno inseriti in questo resoconto) su campioni prodotti in INRiM tramite CVD su cobalto, lasciando presagire che i risultati non siano dovuti al materiale utilizzato ma al miglioramento del processo. The aim of this report is to summarize the recent developments that the production of graphene devices has had in the INRiM laboratories. The study was carried out on commercial graphene grown by Chemical Vapor Deposition (CVD) on Cu and then transferred on an insulating support (SiO2). The Dirac point has been measured, for the first time in INRiM on CVD grown graphene devices produced in the QR laboratories and in Nanofacility Piemonte. The optimized process was then tested previously (in fact, the results will not be included in this report) on samples produced in INRiM via CVD on Co. As a consequence the results seems not to be due to the material used, but to the improvements of the process
A correlation noise spectrometer for flicker noise measurement in graphene samples
Full text linkWe present a high-resolution digital correlation spectrum analyzer for the measurement of low frequency resistance fluctuations in graphene samples. The system exploits the cross-correlation method to reject the amplifiers' noise. The graphene sample is excited with a low-noise DC current. The output voltage is fed to two two-stage low-noise amplifiers connected in parallel; the DC signal component is filtered by a high-pass filter with a cutoff frequency of 34 mHz. The amplified signals are digitized by a two-channel synchronous ADC board; the cross-periodogram, which rejects uncorrelated amplifiers' noise components, is computed in real time. As a practical example, we measured the noise cross-spectrum of graphene samples in the frequency range from 0.153 Hz to 10 kHz, both in two- and four-wire configurations, and for different bias currents. We report here the measurement setup, the data analysis and the error sources
Bridge on a chip: realization of a Kelvin bridge based on quantum Hall elements for resistance calibration
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Realizzazione dell’Ohm e di una Scala di Resistenza Elettrica: Metodi di Misura a Confronto
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
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
Longitudinal Impedance Measurements on Graphene QHE Devices
Full text linkThis paper addresses the challenges associated with accurately measuring longitudinal impedance in a quantum Hall device. A novel bridge design capable of measuring both real and imaginary components of longitudinal impedance is introduced and applied for the first time. The measured inductance appears to be independent of both carrier density and mobility. Additionally, the inductance remains constant over the frequency range from 600 Hz to 50 kHz
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