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Data for 'Impact of ultra-thin Al2O3–y layers on TiO2–x ReRAM switching characteristics'
No full textData accompanying the paper: Prodromakis, Themistoklis; Trapatseli, Maria; Cortese, Simone; Serb, Alexantrou / Improved switching characteristics of TiO2-x ReRAM with embedded ultra-thin 2 Al2O3-y layers.
In: Journal of Applied Physics, 28.03.2017.
Abstract for accompanying paper:
Transition metal-oxide resistive random access memory (RRAM) devices have demonstrated excellent performance in switching speed, versatility of switching and low-power operation. However, this technology still faces challenges like poor cycling endurance, degradation due to high electro-forming switching voltages and low yields. Engineering of the active layer by doping or addition of thin oxide buffer layers, are approaches that have been often adopted to tackle these problems. Here, we have followed a strategy that combines the two; we have used ultra-thin Al2O3-y buffer layers incorporated between TiO2-x thin lms taking into account both 3+/4+ oxidation states of Al/Ti cations. Our devices were tested by DC and pulsed voltage sweeping and in both cases demonstrated improved switching voltages. We believe that the Al2O3-y layers act as reservoirs of oxygen vacancies which are injected during EF, facilitate a lamentary switching mechanism and provide enhanced lament stability as shown by the cycling endurance measurements.</span
On the origin of resistive switching volatility in Ni/TiO2/Ni stacks
No full textData for the paper "Cortese, Simone, Trapatseli, Maria and Khiat, Ali et al. (2016) On the origin of resistive switching volatility in Ni/TiO2/Ni stacks. Journal of Applied Physics"
The file contains all the current versus voltage measurements described in the paper: the resistive switching mechanism curves are presented, as well as subthreshold effects related to the filament instability. The area dependence of the resistances involved is also present in the file.
Data licensed as GNU GPL (http://www.gnu.org/licenses/gpl-2.0.html).</span
A TiO2-based volatile threshold switching selector service with 10^7 non linearity and sub 100 pA Off Current
No full textData for the conference paper:
A TiO2-based volatile threshold Switching Selector Device with 10^7 non linearity and sub 100 pA Off Current.
The file features the Resistive Switching Characteristics of the volatile selector at both polarities, including electroforming step, showing a non linearity of 10^7 between high and low resistance states. Also, the linearity of the low resistance states is presented, showing that the resistance values are the same at both polarities.</span
Engineering the switching dynamics of TiOx-based RRAM with Al doping
No full textTitanium oxide (TiOx) has attracted a lot of attention as an active material for Resistive Random Access Memory (RRAM), due to its versatility and variety of possible crystal phases. Although existing RRAM materials have demonstrated impressive characteristics, like ultra-fast switching and high cycling endurance, this technology still encounters challenges like low yields, large variability of switching characteristics and ultimately device failure. Electroforming (EF) has been often considered responsible for introducing irreversible damage to devices, with high switching voltages contributing to device degradation. In this paper, we have employed Al doping for tuning the resistive switching characteristics of titanium oxide RRAM. The resistive switching (RS) threshold voltages of undoped and Al-doped TiOx thin films were first assessed by Conductive Atomic Force Microscopy (C-AFM). The thin films were then transferred in RRAM devices and tested with voltage pulse sweeping, demonstrating that the Al-doped devices could on average form at lower potentials compared to the undoped ones and could support both analog and binary switching at potentials as low as 0.9 V. This work demonstrates a potential pathway for implementing low-power RRAM systems.
Dataset for:
Trapatseli, Maria, Khiat, Ali and Cortese, Simone et al. (2016) Engineering the switching dynamics of TiOx-based RRAM with Al doping. Journal of Applied Physics, 120, 025108.</span
Doping controlled resistive switching dynamics in transition metal oxide thin films
No full textTransition metal oxide thin films have attracted increasing attention due to their potential in non-volatile resistive random access memory (RRAM) devices, where such thin films are used as active layers in metal-insulator-metal (MIM) configurations. Titanium dioxide is one of the most celebrated oxides among the ones that exhibit resistive switching behaviour due to its wide band gap, high thermal stability, and high dielectric constant. RRAM devices with various materials as active layers, have demonstrated very fast switching performance but also huge potential for miniaturisation, which is the bottleneck of FLASH memory. Nevertheless, these devices very often suffer poor endurance, physical degradation, large variability of switching parameters and low yields. In most cases, the physical degradation stems from high electroforming and switching voltages. Doping of the active layer has been often employed to enhance the performance of RRAM devices, like endurance, OFF/ON ratio, forming voltages, etc. In this work, doping in TiO2-x RRAM devices was used to engineer the electroforming and switching thresholds so that device degradation and failure can be delayed or prevented. Al and Nb were selected with basic criteria the ionic radius and the oxidation state. The doped RRAM devices, showed improved switching performance compared to their undoped counterparts. Alternative approaches to doping were also investigated, like multilayer stacks comprising Al2O3-y and TiO2-x thin films. Furthermore, Al:TiO2-x/Nb:TiO2-x bilayer RRAM devices were fabricated, to prove whether a diode behaviour of the p-n interface inside the RRAM was feasible. The latest would be a particularly interesting finding towards active electronics
A TiO<sub>2</sub>-based volatile threshold Switching Selector Device with 10<sup>7</sup> non linearity and sub 100 pA Off Current
No full textImpact of ultra-thin Al<sub>2</sub>O<sub>3–y</sub> layers on TiO<sub>2–x</sub> ReRAM switching characteristics
No full textTransition metal-oxide resistive random access memory devices have demonstrated excellent performance in switching speed, versatility of switching and low-power operation. However, this technology still faces challenges like poor cycling endurance, degradation due to high electroforming (EF) switching voltages and low yields. Approaches such as engineering of the active layer by doping or addition of thin oxide buffer layers have been often adopted to tackle these problems. Here, we have followed a strategy that combines the two; we have used ultra-thin Al2O3–y buffer layers incorporated between TiO2–x thin films taking into account both 3þ/4þ oxidation states of Al/Ti cations. Our devices were tested by DC and pulsed voltage sweeping and in both cases demonstrated improved switching voltages. We believe that the Al2O3–y layers act as reservoirs of oxygen vacancies which are injected during EF, facilitate a filamentary switching mechanism and provide enhanced filament stability, as shown by the cycling endurance measurements
Spike sorting using non-volatile metal-oxide memristors
No full textElectrophysiological techniques have improved substantially over the past years to the point that neuroprosthetics applications are becoming viable. This evolution has been fuelled by the advancement of implantable microelectrode technologies that have followed their own version of Moore's scaling law. Similarly to electronics, however, excessive data-rates and strained power budgets require the development of more efficient computation paradigms for handling neural data in situ; in particular the computationally heavy task of events classification. Here, we demonstrate how the intrinsic analogue programmability of memristive devices can be exploited to perform spike-sorting on single devices. Leveraging the physical properties of nanoscale memristors allows us to demonstrate that these devices can capture enough information in neural signal for performing spike detection (shown previously) and spike sorting at no additional power cost.</p
Al-doping engineered electroforming and switching dynamics of TiO<sub>x</sub> ReRAM devices
No full textTiO2 thin films have drawn a lot of attention for their application in emerging memory devices, such as resistive random access memory (ReRAM). However, TiO2 ReRAM still faces reliability issues, including poor endurance, large device-to-device and cycle-to-cycle variability of switching parameters and low yields. Moreover, high electroforming voltages have been often associated with irreversible damage to devices. Doping of TiO2 has been employed as a strategy for overcoming these issues. Therefore in this work, we used Al as a dopant in TiO2 thin films to investigate its effect on electroforming and switching voltages of ReRAM devices. Conductive atomic force microscopy (C-AFM) measurements on these thin films, suggested that Al doping decreased the switching voltages compared to the undoped thin films. This result was confirmed by pulse voltage sweeping of ReRAM devices employing the same doped thin films. The Al-doped devices were on average electroforming at -5.7 V, compared to -6.4 V for the undoped ones, and they were switching with potentials as low as ±0.9 V. These findings suggest a potential pathway for implementing low-power ReRAM systems<br/
On the origin of resistive switching volatility in Ni/TiO<sub>2</sub>/Ni stacks
Full text linkResistive switching and resistive random access memories have attracted huge interest for next generation nonvolatile memory applications, also thought to be able to overcome flash memories limitations when arranged in crossbar arrays. A cornerstone of their potential success is that the toggling between two distinct resistance states, usually a High Resistive State (HRS) and a Low Resistive State (LRS), is an intrinsic non-volatile phenomenon with the two states being thermodynamically stable. TiO2 is one of the most common materials known to support non-volatile RS. In this paper, we report a volatile resistive switching in a titanium dioxide thin film sandwiched by two nickel electrodes. The aim of this work is to understand the underlying physical mechanism that triggers the volatile effect, which is ascribed to the presence of a NiO layer at the bottom interface. The NiO layer alters the equilibrium between electric field driven filament formation and thermal enhanced ion diffusion, resulting in the volatile behaviour. Although the volatility is not ideal for non-volatile memory applications, it shows merit for access devices in crossbar arrays due to its high LRS/HRS ratio, which are also briefly discussed
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