Reduction of the forming voltage through tailored oxygen non-stoichiometry in tantalum oxide ReRAM devices

Skaja, Katharina; Andrä, Michael; Rana, Vikas; Waser, Rainer; Dittmann, Regina; Baeumer, Christoph

doi:10.1038/s41598-018-28992-9

Cited by 45 publications

(32 citation statements)

References 42 publications

(36 reference statements)

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“…The XPS survey spectra of representative CoF‐2 and CoF‐3 samples reveal the O/Co ratios to be 2.28 and 2.48, respectively, which correspond to 43 and 38 % O defects, respectively. Our method of O defect estimation is different from that employed by Skaja et al., in which oxygen nonstoichiometry was induced by Ar/O 2 flow rates and binding energy shifts were monitored to estimate the oxygen deficiency . The Rietveld refinement and XPS data are duly corroborated by Raman spectroscopy analysis, which shows a shift of the E g mode to longer wavenumbers for CoF‐2 and CoF‐3, indicating predominant lattice distortion in these two catalysts.…”

Section: Resultsmentioning

confidence: 86%

Oxygen‐Defect‐Rich Cobalt Ferrite Nanoparticles for Practical Water Electrolysis with High Activity and Durability

et al. 2020

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The scope of any metal oxide as a catalyst for driving electrocatalytic reactions depends on its electronic structure, which is correlated to its oxygen‐defect density. Likewise, to transform a spinel oxide, such as cobalt ferrite (CoFe2O4), into a worthy universal‐pH, bifunctional electrocatalyst for the hydrogen and oxygen evolution reactions (HER and OER, respectively), oxygen defects need to be regulated. Prepared by coprecipitation and inert calcination at 650 °C, CoFe2O4 nanoparticles (NPs) require 253 and 300 mV OER overpotentials to reach current densities of 10 and 100 mA cm−2, respectively, if nickel foam is used as a substrate. With cost‐effective carbon fiber paper, the OER overpotential increases to 372 mV at 10 mA cm−2 at pH 14. The NPs prepared at 550 °C require HER overpotentials of 218, 245, and 314 mV at −10 mA cm−2 in alkaline, acidic, and neutral pH, respectively. The intrinsic activity is reflected from turnover frequencies of >3 O2 s−1 and >5 H2 s−1 at overpotentials of 398 and 259 mV, respectively. If coupled for overall water splitting, the extremely durable two‐electrode electrolyzer requires a cell potential of only 1.63 V to reach 10 mA cm−2 at pH 14. The homologous couple also splits seawater at impressively low cell voltages of 1.72 and 1.47 V at room temperature and 80 °C, respectively.

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Section: Resultsmentioning

confidence: 86%

Oxygen‐Defect‐Rich Cobalt Ferrite Nanoparticles for Practical Water Electrolysis with High Activity and Durability

et al. 2020

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“…To determine the variation of oxygen vacancy content, an XPS analysis was carried out. [29], respectively. By increasing the P O2 , the portion of oxygen vacancy was gradually decreased.…”

Section: Methodsmentioning

confidence: 97%

“…deconvoluted to two main peaks centred at around ~530 eV and 531.0~531.5 eV. The peaks at ~530 eV and 531.0-531.5 eV represent the oxygen species in metal-oxygen-metal (M-O-M) and near the oxygen vacancy (O-M-Ovac) [29], respectively. By increasing the PO2, the portion of oxygen vacancy was gradually decreased.…”

Section: Methodsmentioning

confidence: 99%

The Effect of Multi-Layer Stacking Sequence of TiOx Active Layers on the Resistive-Switching Characteristics of Memristor Devices

et al. 2020

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The oxygen vacancies in the TiOx active layer play the key role in determining the electrical characteristics of TiOx–based memristors such as resistive-switching behaviour. In this paper, we investigated the effect of a multi-layer stacking sequence of TiOx active layers on the resistive-switching characteristics of memristor devices. In particular, the stacking sequence of the multi-layer TiOx sub-layers, which have different oxygen contents, was varied. The optimal stacking sequence condition was confirmed by measuring the current–voltage characteristics, and also the retention test confirmed that the characteristics were maintained for more than 10,000 s. Finally, the simulation using the Modified National Institute of Standards and Technology handwriting recognition data set revealed that the multi-layer TiOx memristors showed a learning accuracy of 89.18%, demonstrating the practical utilization of the multi-layer TiOx memristors in artificial intelligence systems.

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“…[ 1 , 2 , 3 , 4 ]. So far, RRAM has been reported in a variety of material systems, including organic materials [ 5 ], complex composition materials [ 6 ], and binary transition metal oxide materials [ 7 , 8 ]. In addition, compared with the other material systems, various new types of metal-oxide based RRAM devices are being devised, attributable to their potential advantages [ 9 , 10 ], as well as excellent compatibility with the current complementary metal oxide semiconductor (CMOS) technology [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Li-Doping Effect on Characteristics of ZnO Thin Films Resistive Random Access Memory

et al. 2020

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In this study, a Pt/Ag/LZO/Pt resistive random access memory (RRAM), doped by different Li-doping concentrations was designed and fabricated by using a magnetron sputtering method. To determine how the Li-doping concentration affects the crystal lattice structure in the composite ZnO thin films, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) tests were carried out. The resistive switching behaviors of the resulting Pt/Ag/LZO/Pt devices, with different Li-doping contents, were studied under direct current (DC) and pulse voltages. The experimental results showed that compared with the devices doped with Li-8% and -10%, the ZnO based RRAM device doped by 5% Li-doping presented stable bipolar resistive switching behaviors with DC voltage, including a low switching voltage (<1.0 V), a high endurance (>103 cycles), long retention time (>104 s), and a large resistive switching window. In addition, quick switching between a high-resistance state (HRS) and a low-resistance state (LRS) was achieved at a pulse voltage. To investigate the resistive switching mechanism of the device, a conduction model was installed based on Ag conducting filament transmission. The study of the resulting Pt/Ag/LZO/Pt devices makes it possible to further improve the performance of RRAM devices.

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Reduction of the forming voltage through tailored oxygen non-stoichiometry in tantalum oxide ReRAM devices

Cited by 45 publications

References 42 publications

Oxygen‐Defect‐Rich Cobalt Ferrite Nanoparticles for Practical Water Electrolysis with High Activity and Durability

Oxygen‐Defect‐Rich Cobalt Ferrite Nanoparticles for Practical Water Electrolysis with High Activity and Durability

The Effect of Multi-Layer Stacking Sequence of TiOx Active Layers on the Resistive-Switching Characteristics of Memristor Devices

Li-Doping Effect on Characteristics of ZnO Thin Films Resistive Random Access Memory

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