1,722,472 research outputs found
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
The Impact of Electrostatic Interactions between Defects on the Characteristics of Random Telegraph Noise
No full textRandom telegraph noise (RTN) is one of the most challenging defect-related reliability concerns in emerging HfO2-based devices due to the higher bulk defect density compared to SiO2. Despite many research efforts, the physical mechanisms determining complex signals (e.g., multilevel, anomalous, temporary RTN) are still unclear and need a deeper investigation. With this driving force, we performed physic-based kinetic Monte Carlo (kMC) simulations in a TiN/HfO2/TiN cell to directly analyze the role of defects which promote RTN, both in steady state and transient regime. The nonmonotonic trends of the ratio of the RTN dwell times with the applied bias frequently found in the literature are found to be caused by changes with the applied voltage of the preferential capture/emission source/destination of traps. The in-depth analysis sheds new light on the conventional methods for defect classification and vertical position estimation. Moreover, such source/destination changes also occur over time due to the dynamics of the local electric field, which varies with the evolution of the surrounding electrostatic landscape. Notably, the local field is given by the overlap of the applied voltage and of the trapped charge contributions, the latter being dominant at low voltages. The analysis of the Markov chains of closely spaced defects shown interdependencies and alterations of the RTN capture and emission times. A new method is proposed to include the impact of electrostatic interactions between defects on RTN
Nascere con la tecnica. Una ricerca sull'accettazione sociale della procreazione artificiale
No full textDi fronte all'innovazione tecnico-scientifica, qual è il caso delle nuove tecnologie riproduttive, i mass media giocano un ruolo fondamentale di diffusione e costruzione di una conoscenza di seconda mano. L'informazione veicolata non trasmette solo la formazione di credenze e atteggiamenti ma anche le categorie concettuali entro cui collocare le informazioni comunicate. La presente ricerca sperimentale misura le reazioni di un campione di partecipanti posti di fronte a un caso di procreazione assistita di cui sono stati modulati diversi livelli rappresentativi (naturale vs artificiale; finalità intervento; procedure di intervento)
Mobile agent solutions for accounting management in mobile computing
No full textThe convergence of mobile tele communications and the Internet global system forces to reconsider traditional client/server solutions for network and systems management. The paper claims that accounting in the mobility-enabled Internet requires support infrastructures hosted in the fixed network, These infrastructures should monitor, control and register resource consumption locally within the domains where users/terminals dynamically move to, without requiring continuous connectivity with remote and centralized accounting home managers. In addition, the paper shows that the Mobile Agent (HA) technology is suitable to overcome the limits of traditional accounting solutions in several mobility-enabled usage scenarios. MAs can maximize locality in accessing monitoring data, can enable accounting even in case of temporary disconnection, can install new monitoring/control behavior dynamically, and can support session-dependent solutions. The paper finally presents the design and implementation of the MA-based Middleware for Mobility Accounting Management (MAM(2)), together with some use cases showing the advantages of the MA adoption
Local electric field perturbations due to trapping mechanisms at defects: What random telegraph noise reveals
Full text linkAs devices scale closer to the atomic size, a complete understanding of the physical mechanisms involving defects in high-kappa dielectrics is essential to improve the performance of electron devices and to mitigate key reliability phenomena, such as Random Telegraph Noise (RTN). In fact, crucial aspects of defects in HfO2 are still under investigation (e.g., the presence of metastable states and their properties), but it is well known that oxygen vacancies (V(+)s) and oxygen ions (O(0)s) are the most abundant defects in HfO2. In this work, we use simulations to gain insights into the RTN that emerges when a constant voltage is applied across a TiN/(4 nm)HfO2/TiN stack. Signals exhibit different RTN properties over bias and, thus, appear to originate from different traps. Yet, we demonstrate that they can be instead promoted by the same O(0)s which change their capture (tau(c)) and emission (tau(e)) time constants with the applied bias, which, in turn, changes the extent of their electrostatic interactions with the traps that assist charge transport (V(+)s). For a certain bias, RTN is given by the modulation of the trap-assisted current at V(+)s induced by trapping/detrapping events at O(0)s, which are, in turn, influenced by the bias itself and by trapped charge at nearby O(0)s. In this work, we demonstrate that accounting for the effect of trapped charge is essential to provide accurate estimation of the RTN parameters, which allow us to retrieve information about traps and to explain key mechanisms behind complex RTN signals
Linking the Intrinsic Electrical Response of Ferroelectric Devices to Material Properties by means of Impedance Spectroscopy
Full text linkFerroelectric devices have gained attention in recent
years as a potential solution for ultra-low power computing due
to their ability to act as memory units and synaptic weights in
brain-inspired architectures. One way to study the behavior of
these devices under different conditions, particularly the
influence of material composition and charge trapping on
ferroelectric switching, is through impedance spectroscopy.
However, the parasitic impedance of the metal lines that contact
the electrodes of the device can affect the measured response and
interpretation of the results. In this study, we examined the
frequency response of ferroelectric tunnel junctions (FTJs) with
a metal-dielectric-ferroelectric-metal (MDFM) stack at various
voltages, starting from the analysis of single layer capacitors
(MFM and MDM) to better interpret FTJ’s results. To
accurately assess the intrinsic response of the device, we
developed a method that estimates and removes the parasitic
access impedance contribution, which was validated by means of
physics-based simulations. This method allows quantifying the
intrinsic device-level variability of FTJs and, for the first time, to
investigate the relation between the thickness of the dielectric
layer, the equivalent phase composition of the ferroelectric
material, and the magnitude of the peak in the frequency
response, often assumed to be related to charge trapping only
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