1,721,169 research outputs found
Hybrid circuit analysis of a suspended-gate silicon nanodot memory (SGSNM) cell
No full textWe report a hybrid numerical analysis of the suspended gate silicon nanodot memory (SGSNM) which co-integrates nano-electromechanical systems (NEMS) with silicon MOSFET technology. We propose a new hybrid equivalent circuit model for the SGSNM, in which a parallel-connected variable gate capacitance and variable tunnel resistance model the suspended gate pull-in/pull-out operation and the electron tunnelling process through the tunnelling oxide layer. The signals for the programming, erasing and reading processes are successfully achieved in the circuit level simulation. The programming/erasing speed is found 2.5 ns which is a combination between the mechanical SG pull-in (0.8 ns) and the tunnelling process (1.7 ns). Those characteristics and the fact that the SGSNM does not use exotic materials but Si-based materials, makes the SGSNM a serious candidate for non-volatile random access memory applications
Suspended Gate Silicon Nanodot Memory
No full textThe non-volatile memory market has been driven by Flash memory since its invention more than three decades ago. Today, this non-volatile memory is used in a wide variety of devices and systems from pen drives, mp3 players to cars, planes and satellites. However,the conventional floating gate memory technology in use for flash memory is facing a serious scalability issue, the tunnel oxide thickness cannot be reduced to less than 7nm as pointed out in the latest international technology roadmap for semiconductors (ITRS2010) [1]. The limit imposed on the tunnel oxide layer reduces the programming and erasing times, the scalability and endurance among other parameters. To overcome those inherent issues, this research is focused on the co-integration of nano-electromechanical systems (NEMS) with metal-oxide-semiconductor (MOS) technology in order to generate a new non-volatile and high speed memory. The memory device that we are proposing is a high-speed non-volatile memory structure called the Suspended Gate Silicon Nanodot Memory (SGSNM) cell. This non-volatile memory device features a MOSFET as a readout element, a silicon nanodot (SiNDs) monolayer as the floating gate and a movable suspended control gate isolated from the floating gate by an oxide layer and by an air-gap. The fundamental component in this novel device is the introduction of a doubly-clamped beam as a movable control gate, in which through this element, the programming and erasing operations take place. To understand the behaviour of the doubly-clamped beam structure, it is analysed by using analytical models such as the doubly-plate capacitor model and also by using two- and three-dimensional (2D and 3D) finite element method (FEM) analysis. The programming and erasing operations within the SGSNM occur when the suspended control gate is in contact with the tunnel oxide layer. This is the point at which the quantum-mechanical tunnelling mechanism (Fowler-Nordheim) takes place. Through this mechanism, the electrons are allowed to tunnel from the suspended control gate into the memory node and vice versa as a function of the applied voltage (bias). The tunnelling process is numerically analysed by implementing the Tsu-Esaki equation and the transfer matrix method within a homemade program which calculates the current density as a function of the tunnel oxide material and thickness. Both the suspended control gate and tunnelling process are implemented as analog behavioural models within the SGSNM cell that is simulated by using a commercial circuit simulator. From a transient analysis of the suspended control gate, it was found that the suspended control gate takes 0.8 nsec in pull-in on the tunnel oxide layer for a 1 ?m-long doubly-clamped structure. In contrast, the time that the memory node takes in charge and discharge is 1.7 nsec. Hence, the programming and erasing times are a combination between the mechanical pull-in and the charging time, which is 2.5 nsec due the fact that to both operations are symmetrical. Moreover, the suspended control gate was successfully fabricated and suspended. This process was performed by depositing a thin layer of aluminium (500 nm) over the sacrificial layer (poly-Si) by using an e-beam evaporator, which was patterned with doubly-clamped beam features through the photolithographic process. By using a combination of wet and dry etching processes, the aluminium and the sacrificial layer were successfully removed without affecting the substrate (Si-based) or the suspended control gate beam. In addition, Capacitance - Voltage measurements were performed on a set of doubly-clamped beams from which the pull-in effect was successfully obtained. Finally, the footprints for the memory device fabrication process were developed and sketched within the document as well as the design of three photomask
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
Suspended Gate Silicon Nanodots memory
No full textThis paper proposes a new non-volatile semiconductor memory which features a suspended gate integrated with silicon nanocrystals dots as a floating gate and the MOSFET as a readout. Performing three-dimensional finite element simulations combined with an analytical plate-capacitor model, we clarify the pull-in/pull-out operation of the suspended gate. We also show the dependence of the hysteresis cycle characteristics on material and structural parameters
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