1,721,024 research outputs found
Quantum effects in accumulated MOS thin dielectric structures
No full textThe role of quantum effects, strongly modifying the physics of SiSiO2 interfaces in accumulated thin-oxide MOS structures, is reviewed and discussed. The main differences with respect to the classical case are analysed: in particular, it is shown that the semiconductor voltage drop and the oxide barrier height for Fowler-Nordheim tunnel injection are largely modified by the quantization of the accumulation layers. The dependence of the barrier height on the oxide field has a remarkable impact on the modelling of thin oxides: in particular, the Fowler-Nordheim current is shown to be correctly estimated only if quantum effects are correctly taken into account. © 1994
On the Determination of the Si-SiO2 Barrier Height from the Fowler-Nordheim Plot
No full textIn this paper it is shown that, even considering a field-dependent Si–SiO2 barrier height for electron tunneling as predicted by the quantum-mechanical (QM) modeling of Si–SiO2 interfaces, the Fowler–Nordheim (F-N) plot is linear. It is proven that the “equivalent” barrier height extracted from the graph slope is not representative of the actual field-dependent barrier. The problem of correctly estimating the oxide field to be used in F-N plots is also addressed. © 1991 IEE
Quantum-Mechanical Modeling of Accumulation Layers in MOS Structures
No full textAn original method is used for the quantum-mechanical modeling of n-type silicon accumulation layers. Contrarily to previous methods, which were only valid near 4.2 K, our approach is valid up to room temperature and beyond. The obtained self-consistent results are compared with those of the standard classical model for the accumulation layer, and the differences between them are found to be relevant for the modeling of important device applications. In particular, it is shown that the semiconductor voltage drop and the oxide barrier height for Fowler-Nordheim (F-N) tunnel injection are largely modified by the quantization of the accumulation layer. The dependences of these two magnitudes (accumulation voltage drop and effective F-N barrier height) on oxide electric field and substrate doping are reported. Experimental F-N current-voltage characteristics of production-quality -Si(n)/Si02/poly-Si(n+) MOS capacitors are used to validate the presented quantum ..
Temperature Dependence of Fowler-Nordheim Injection from Accumulated n-type Silicon into Silicon Dioxide
No full textThe temperature dependence of the Fowler-Nordheim (F-N) injection of electrons from accumulated n-Si to SiO2 is analyzed. The F-N current-voltage characteristics of thin-oxide (8.5 nm) 〈100〉-Si(n)/SiO2/poly-Si(n+) MOS capacitors have been measured at different temperatures ranging from 90 to 473 K. The obtained results are explained treating the accumulation layer quantum-mechanically, i.e., taking into account the injection of electrons from quantized energy subbands. In order to facilitate the use of the presented results in compact device simulators, simple analytical expressions which give the F-N current as a function of temperature have been derived from our self-consistent quantum-mechanical calculations. © 1993 IEE
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
Simulation of the time-dependent breakdown characteristics of heavy ion irradiated gate oxides using a mean-reverting poisson-gaussian process
No full textIn this work, a compact mathematical representation of the time-dependent breakdown dynamics of heavy ion irradiated thin oxides subjected to electrical stress is investigated. The model is formulated as a stochastic differential equation for the gate leakage current consisting of a deterministic term and two random terms. The first one deals with the short transient and evolution toward the steady state conduction level after the triggering of the breakdown event, the second one simulates the noisy behavior between the arrival of events and the third term represents the opening of successive breakdown paths across the dielectric film. Ion hits are assumed to cause a finite number of latent damaged sites distributed throughout the oxide area, which manifest, as the electrical stress proceeds, in the long-run saturating behavior of the current-time characteristics. A non-homogeneous Poisson counting process is used to describe the switching from latent to active spot while a gaussian process is considered for the low-level fluctuations
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
Transient simulation of the erase cycle of floating gate EEPROMs
No full textThe validity of a steady-state approach to the simulation of the WRITE/ERASE cycles of floating gate EEPROM cells is discussed. It is shown that, while the WRITE cycle can be always accurately modeled in such a framework, the simulation of the ERASE cycle sometimes requires a transient analysis to correctly account for the deep depletion of the drain during the leading edge of the ERASE pulse. An approximate method for the fast transient simulation of the ERASE cycle is presented. A comparison of experiments and simulations demonstrates the relevance of the non-steady-state effects, and supports the validity of the presented transient solution. In addition, it is shown that an accurate simulation of WRITE/ERASE cycles requires a reliable model for Fowler-Nordheim injection from an accumulated semiconductor
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