Analysis of V<sub>th</sub> variability in NbO<sub>x</sub>-based threshold switches

Slesazeck, Stefan; Herzig, Melanie; Mikolajick, Thomas; Ascoli, Alon; Weiher, Martin; Tetzlaff, Ronald

doi:10.1109/nvmts.2016.7781515

Cited by 7 publications

(9 citation statements)

References 7 publications

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“…When no parallel capacitor was used, only negligible instable oscillations could be experimentally observed (see figure 3(a)). Furthermore, a minimum parallel electrical capacitance is necessary to ensure that the product between electrical resist ance and electrical capacitance in the oscillator circuit (R ser C par ) is significantly larger than the product between thermal capacitance and thermal resistance of the threshold switching device (R th C th with R th = 1/Γ th ) [13,14]. If the latter condition is not fulfilled the internal heating and cooling rate of the filament at a given Joule heating is not Table 1.…”

Section: Correlations Between Dynamic Behavior Of the Threshold Switc...mentioning

confidence: 99%

Multiple slopes in the negative differential resistance region of NbO_x-based threshold switches

Herzig

Weiher

Ascoli

et al. 2019

J. Phys. D: Appl. Phys.

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Niobium oxide devices exhibit threshold switching behavior which enables their use as selectors in memory arrays or as locally active devices for neuromorphic computing. Among the basic dynamical phenomena appearing in non-linear circuits, the oscillations generated in a relaxation oscillator, which is making use of the negative differential resistance (NDR) effect of a threshold switching device, are of special significance for the design of neuromorphic electronic systems. Here, the necessary requirements for the emergence of oscillations of this kind in a simple relaxation oscillator circuit and their influence on the shape of the measured quasi-static I– characteristic of the threshold switch are examined. In the corresponding experiments multiple NDR regions were found to appear in the quasi-static I– characteristic of the threshold switch concurrently with the occurrence of oscillations. The observed ‘multiple NDR phenomenon’ is therefore merely a measurement artefact due to the averaging effect associated to the operating principles of the source measure unit (SMU) utilized to measure the device current and voltage. In this work, we analyzed how the emergence of oscillatory behavior in the relaxation oscillator depends upon the device layer stack composition. The probability of the appearance of oscillations within a large current range can be increased by decreasing the oxygen content in the sub-stoichiometric bottom layer of a niobium oxide bi-layer stack. It is shown that this trend is caused by the resulting decrease in the value of the product between thermal capacitance and thermal resistance of the threshold switching device. Furthermore, the changed stack composition reduces the variability and changes the forming voltage, which goes hand in hand with a change of the threshold voltage.

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Section: Correlations Between Dynamic Behavior Of the Threshold Switc...mentioning

confidence: 99%

Multiple slopes in the negative differential resistance region of NbO_x-based threshold switches

Herzig

Weiher

Ascoli

et al. 2019

J. Phys. D: Appl. Phys.

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“…10 Memristive devices based on NbO x have been also largely studied for their threshold switching properties, useful as a selector in memory arrays. [11][12][13][14][15][16][17][18][19][20][21][22][23] In all these works, the niobium oxide switching medium is obtained using conventional deposition techniques such as RF sputtering both starting from a NbO x target and from a pure Nb target in an oxygen atmosphere to control its stoichiometry and also by using pulsed laser deposition (PLD), ALD and sol-gel methods. [24][25][26][27][28][29] Recently, anodic oxidation has been proposed as a promising alternative low-cost and easy-to-use technique in the realization of RS devices with high performances.…”

Section: Introductionmentioning

confidence: 99%

“…10 Memristive devices based on NbO x have been also largely studied for their threshold switching properties, useful as a selector in memory arrays. 11–23 In all these works, the niobium oxide switching medium is obtained using conventional deposition techniques such as RF sputtering both starting from a NbO x target and from a pure Nb target in an oxygen atmosphere to control its stoichiometry and also by using pulsed laser deposition (PLD), ALD and sol–gel methods. 24–29…”

Section: Introductionmentioning

confidence: 99%

Resistive switching and role of interfaces in memristive devices based on amorphous NbO_x grown by anodic oxidation

Leonetti

Fretto

Olivetti

et al. 2023

Phys. Chem. Chem. Phys.

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“…However, if higher currents are let flow through the device, the latter is found to feature distinct resistive levels for no input (Mähne et al, 2013) besides maintaining an abrupt switching behavior upon excitation. For modeling the NbO memristor accurately under these circumstances, the dynamic law of another non-volatile memory state needs to be specified (Slesazeck et al, 2016). Since the device was operated in the low current regime during all the experimental investigations associated to this research, a volatile memristor model is adopted non-linear dynamics of a micro-scale NbO volatile resistance switching memory from NaMlab was found to be captured accurately by a voltage-controlled generic memristor model, reading as the DAE set (3) and ( 4), where the state evolution and memductance functions are respectively, expressed by…”

Section: Application Of a Non-linear System Identification Technique For Modeling A Nbo Volatile Memristormentioning

confidence: 99%

On Local Activity and Edge of Chaos in a NaMLab Memristor

et al. 2021

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Local activity is the capability of a system to amplify infinitesimal fluctuations in energy. Complex phenomena, including the generation of action potentials in neuronal axon membranes, may never emerge in an open system unless some of its constitutive elements operate in a locally active regime. As a result, the recent discovery of solid-state volatile memory devices, which, biased through appropriate DC sources, may enter a local activity domain, and, most importantly, the associated stable yet excitable sub-domain, referred to as edge of chaos, which is where the seed of complexity is actually planted, is of great appeal to the neuromorphic engineering community. This paper applies fundamentals from the theory of local activity to an accurate model of a niobium oxide volatile resistance switching memory to derive the conditions necessary to bias the device in the local activity regime. This allows to partition the entire design parameter space into three domains, where the threshold switch is locally passive (LP), locally active but unstable, and both locally active and stable, respectively. The final part of the article is devoted to point out the extent by which the response of the volatile memristor to quasi-static excitations may differ from its dynamics under DC stress. Reporting experimental measurements, which validate the theoretical predictions, this work clearly demonstrates how invaluable is non-linear system theory for the acquirement of a comprehensive picture of the dynamics of highly non-linear devices, which is an essential prerequisite for a conscious and systematic approach to the design of robust neuromorphic electronics. Given that, as recently proved, the potassium and sodium ion channels in biological axon membranes are locally active memristors, the physical realization of novel artificial neural networks, capable to reproduce the functionalities of the human brain more closely than state-of-the-art purely CMOS hardware architectures, should not leave aside the adoption of resistance switching memories, which, under the appropriate provision of energy, are capable to amplify the small signal, such as the niobium dioxide micro-scale device from NaMLab, chosen as object of theoretical and experimental study in this work.

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Analysis of V_th variability in NbO_x-based threshold switches

Cited by 7 publications

References 7 publications

Multiple slopes in the negative differential resistance region of NbO_x-based threshold switches

Multiple slopes in the negative differential resistance region of NbO_x-based threshold switches

Resistive switching and role of interfaces in memristive devices based on amorphous NbO_x grown by anodic oxidation

On Local Activity and Edge of Chaos in a NaMLab Memristor

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Analysis of Vth variability in NbOx-based threshold switches

Cited by 7 publications

References 7 publications

Multiple slopes in the negative differential resistance region of NbOx-based threshold switches

Multiple slopes in the negative differential resistance region of NbOx-based threshold switches

Resistive switching and role of interfaces in memristive devices based on amorphous NbOx grown by anodic oxidation

On Local Activity and Edge of Chaos in a NaMLab Memristor

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Analysis of V_th variability in NbO_x-based threshold switches

Multiple slopes in the negative differential resistance region of NbO_x-based threshold switches

Multiple slopes in the negative differential resistance region of NbO_x-based threshold switches

Resistive switching and role of interfaces in memristive devices based on amorphous NbO_x grown by anodic oxidation