1,721,000 research outputs found
Film-nanostructure-controlled inerasable-to-erasable switching transition in ZnO-based transparent memristor devices: sputtering-pressure dependency
No full textWe found that the write-once-read-many-times (WORM, inerasable)-to-rewritable (erasable) transition phenomenon results from the different structures of the filament, which is determined by the grain orientations of the deposited films. The conduction mechanism of this switching transition and its impact on the synaptic behavior in various ZnO nanostructures are also discussed. Furthermore, our WORM devices have a programmable physical damage function that can be exploited for use in security systems against data theft, hacking, and unauthorized use of software/hardware. This work proposes ZnO-based nonvolatile memory for invisible electronic applications and gives valuable insight into the design of WORM and rewritable memories
Transparent ZnO resistive switching memory fabricated by neutral oxygen beam treatment
No full textIn this work, a Cu/ZnO/ITO resistive random access memory (RRAM) structure in which ZnO films are irradiated with neutral oxygen beams was employed to investigate the effect of neutral oxygen beams as a surface treatment. It was confirmed that the treatment reduced the defect concentration in the sputtered-ZnO film and improved the resistance change characteristics of the device. These results indicate the great potential of neutral oxygen beams in the development of RRAM devices using ZnO films
Influence of rf sputter power on ZnO film characteristics for transparent memristor devices
No full textThe impact of the radio-frequency (rf) sputtering power on the switching characteristics of ZnO-based transparent memristor devices hasbeen investigated. Memristor devices made with a high rf power exhibited excellent switching characteristics; meanwhile, decreasing the rfpower led to less-apparent switching behavior and increased likelihood of device breakdown. However, high rf power memristors exhibiteda reduced switching uniformity as the rf power significantly affected the defect concentration as well as the microstructure of the deposited ZnO films, which determine the switching characteristics and performance of memristor devices
Neutral Oxygen Beam Treated ZnO-Based Resistive Switching Memory Device
No full textThe
room-temperature oxidation process allows irradiation with neutral
oxygen particles onto the resistive layer that leads to the absorption
of oxygen by the surface of the ZnO layer. The irradiation is effective
in controlling the defect concentrations; thus, the ON and OFF resistances
of devices can be significantly increased. These characteristics promote
the occurrence of resistive switching at much lower current compliance
as well as induce switching behavior in very thin ZnO films with thicknesses
of 14–42 nm. The thickness dependence of the transformation
from filamentary to homogeneous switching was also studied using the
neutral beam technique, and the underlying mechanism is discussed
Neutral oxygen irradiation enhanced forming-less ZnO-based transparent analog memristor devices for neuromorphic computing applications
No full textSurface oxidation employing neutral oxygen irradiation significantly improves the switching and synaptic performance of ZnO-based transparent memristor devices. The endurance of the as-irradiated deviceis increased by 100 times, and the operating current can be lowered by 10 times as compared with the as-deposited device. Moreover, the performance-enhanced device has an excellent analog behavior that can exhibit 3-bits per cell nonvolatile multistate characteristics and perform 15 stable epochs ofsynaptic operations with highly linear weight updates. A simulated artificial neural network comprising 1600 synapses confirms the superiority of the enhanced device in processing a 40 × 40 pixels grayscale image. The irradiation effectively decreases the concentration of oxygen vacancy donor defects and promotes oxygen interstitial acceptor defects on the surface of the ZnO films, which consequently modulate the redox process during rupture and rejuvenation of the filament. This work not only proposes the potential of ZnO-based memristor devices for high-density invisible data storage and in-memory computing application but also offers valuable insight in designing high-performance memristor devices, regardless of the oxide system used, by taking advantage of our neutral oxygen irradiation technique
Influence of active electrode impurity on memristive characteristics of ECM devices
Get PDFMemristive devices are promising candidates for the implementation in more than Moore applications. Their functionalities, electrical characteristics, and behavior, such as high scalability and stability at extreme conditions such as low/high temperatures, irradiation with electromagnetic waves and high-energy particles, and fast operation are required for solving current problems in neuromorphic architectures. Electrochemical metallization (ECM)-based memristive devices are among the most relevant in this scenario owing to their low power consumption, high switching speed, showing high HRS/LRS resistance ratio in digital mode, and as well multilevel to analogue-type performance, allowing to be used in wide spectrum of applications, including as artificial neurons and/or synapses in brain-inspired hardware. Despite all the advantages and progressing industrial implementation, effects of materials selection and interactions are not sufficiently explored, and reliable design rules based on materials approach are still to be formulated by the correct choice of structures and materials combinations to ensure desired performance. In this work, we report on the effects of impurities in the copper active electrode on the electrical characteristics of Cu/Ta2O5/Pt ECM devices. The results demonstrate that Cu impurity is modulating the electrochemical behavior and switching speed due to different catalytic activity and redox reaction rates. In addition, stability and variability are improved by decreasing the number of foreign atoms. Our results provide important additional information on the factors needed to be considered for rational device design
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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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