Inn-Cnea-Conicet

ABSTRACT An equivalent circuit representation for the conduction characteristics of TiO??-based resistive switches based on the generalized diode equation is reported. The proposed model consists of two antiparallel diodes with series and parallel resistances representing the filamentary current pathway spanning the oxide layer and the possible parasitic conduction effects. The model accounts for the pulse-induced hysteretic behavior exhibited by the I-V characteristic after electroforming. Three different approaches, each one of them with increased complexity, are assessed: 1) constant; 2) nanowire-like; and 3) sigmoidal diode amplitude. In all cases, the logarithmic conductance of the diodes is modeled using a logistic-type threshold function.

ABSTRACT We studied La0.325Pr0.300Ca0.375MnO3-Ag memristive interfaces. We present a pulsing/measuring protocol capable of registering both quasi-static i-v data and non-volatile remnant resistance. This protocol allowed distinguishing two different electronic transport mechanisms coexisting at the memristive interface, namely space charge limited current and thermionic emission limited current. We introduce a 2-element electric model that accounts for the obtained results and allows predicting the quasi-static i-v relation of the interface by means of a simple function of both the applied voltage and the remnant resistance value. Each element of the electric model is associated to one of the electronic transport mechanisms found. This electric model could result useful for developing time-domain simulation models of metal-manganite memristive interfaces.

ABSTRACT We explore different resistance states of La0.325Pr0.300Ca0.375MnO3-Ti interfaces as prototypes of non-volatile memory devices at room temperature. In addition to high and low resistance states accessible through bipolar pulsing with one pulse, higher resistance states can be obtained by repeatedly pulsing with a single polarity. The accumulative action of successive pulsing drives the resistance towards saturation, the time constant being a strong function of the pulsing amplitude. The experiments reveal that the pulsing amplitude and the number of applied pulses necessary to reach a target high resistance value appear to be in an exponential relationship, with a rate that results independent of the resistance value. Model simulations confirm these results and provide the oxygen vacancy profiles associated to the high resistance states obtained in the experiments.

ABSTRACT We report the resistive switching (RS) characteristics of Al/TiO2/Au memristive cells fabricated in a crossbar array. The measured R-V curves suggest that RS takes place essentially at the Au/TiO2 interface. We propose a model based on the electric field enhanced migration of oxygen vacancies at that interface which reproduces the main features of the experimental data, namely the remnant resistance states and the degradation process. Obtained vacancy profiles at the active region of the junction give insight for the design of improved devices.

ABSTRACT We study the electric pulse induced resistance switching of TiO2-Ag contacts at room temperature, exploring both unipolar and bipolar switching modes. Initially we observed unipolar response. After hundred pulsing cycles the unipolar switching response vanishes but the device can still be operated in bipolar switching regime. The underlying mechanism for resistance switching is modeled in terms of formation and rupture of filament, and movement of oxygen vacancies. (C) 2012 Elsevier B.V. All rights reserved

ABSTRACT We probe the resistive switching response of Au/TiO2/Cu junctions, on samples initialized using both polarities electroforming. A conductive path is formed in both cases: a copper metallic filament for negative electroforming and a titanium dioxide possibly Magneli phase based filament for the positive case. We measured the resistance response of formed samples and studied their remanent resistance states. Bi (tri) stable resistance states were obtained for negative (positive) electroformed samples. The temperature dependence of the resistance discloses the underlying different nature of the associated filaments. In addition, we performed ab initio calculations to estimate the observed electroforming threshold voltages.

ABSTRACT An equivalent electrical circuit model for the switching conduction characteristics of TiO2-based metal-insulator-metal structures is proposed. The model consists of two antiparallel diodes in combination with series and parallel resistances, which represent the filamentary current pathway spanning the oxide layer and the possible parasitic conduction effects, respectively. The diode parameters are expressed by sigmoidal-type threshold functions which account for the transition between the low and high resistance states.

Version 0.10 This is a major release of Panel, with a slew of new features and enhancements, plus a wide array of minor fixes and improvements to the documentation, and website. Many thanks to the people who contributed to this release, including @philippjfr, @MarkSkovMadsen (alert pane, templates, docs), @xavArtley (VTK improvements, templates, input/spinner widgets), @maximlt (panel serve), @jbednar (docs, reviewing), @kebowen (templates), @ahuang11 (datepicker), @nghenzi (react template, bugfixes), @nritsche (panel serve), @ltalirz (autocomplete input), @BoBednar (docs), @tmikolajczyk, @halilbay, @Hoxbro, and @ceball (testing and automation). Features: Add <code>Card</code> and <code>Accordion</code> layout (#1262, #1266, #1267, #1616, #1619) Location component (#1150, #1297, #1357, #1407, #1498, #1519, #1532, #1638, #1658) VTK improvements: colorbars (#1270), synchronization (#1248, #1637), orientation widget (#1635), volume controller (#1631), serializat...