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Origin of the OFF state variability in ReRAM cells

Origin of the OFF state variability in ReRAM cells
Origin of the OFF state variability in ReRAM cells
This work exploits the switching dynamics of nanoscale Resistive Random Access Memory (ReRAM) cells with particular emphasis on the origin of the observed variability when consecutively cycled/programmed at distinct memory states. It is demonstrated that this variance is a common feature of all ReRAM elements and is ascribed to the formation and rupture of conductive filaments that expand across the active core, independently of the material employed as the active switching core, the causal physical switching mechanism, the switching mode (bipolar/unipolar) or even the unit cells’ dimensions. Our hypothesis is supported through both experimental and theoretical studies on TiO2 and In2O3:SnO2 (ITO) based ReRAM cells while programmed at three distinct resistive states. Our prototypes employed TiO2 or ITO active cores over 5×5 µm2 and 100x100 µm2 cells’ areas, with all tested devices demonstrating both unipolar and bipolar switching modalities. In the case of TiO2-based cells, the underlying switching mechanism is based on the non-uniform displacement of ionic species that foster the formation of conductive filaments. On the other hand, the resistive switching observed in the ITO-based devices is considered to be due to a phase change mechanism. The selected experimental parameters allowed us to demonstrate that the observed programming variance is a common feature of all ReRAM devices, proving that its origin is dependent upon randomly oriented local disorders within the active core that have a substantial impact in the overall state variance particularly for high-resistive states.
0022-3727
1-10
Salaoru, I.
e3ef4b52-c1df-4ecc-ad0f-472836857407
Khiat, A.
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Berdan, R.
082f1f5b-eaee-48a6-b728-414fc65f72bd
Quingjian, L.
801900bb-987f-499a-8ff4-3559f6d39930
Papavassiliou, C.
5faf408a-ca30-47e5-8283-4a65536f91ff
Prodromakis, T.
d58c9c10-9d25-4d22-b155-06c8437acfbf
Salaoru, I.
e3ef4b52-c1df-4ecc-ad0f-472836857407
Khiat, A.
bf549ddd-5356-4a7d-9c12-eb6c0d904050
Berdan, R.
082f1f5b-eaee-48a6-b728-414fc65f72bd
Quingjian, L.
801900bb-987f-499a-8ff4-3559f6d39930
Papavassiliou, C.
5faf408a-ca30-47e5-8283-4a65536f91ff
Prodromakis, T.
d58c9c10-9d25-4d22-b155-06c8437acfbf

Salaoru, I., Khiat, A., Berdan, R., Quingjian, L., Papavassiliou, C. and Prodromakis, T. (2014) Origin of the OFF state variability in ReRAM cells. Journal of Physics D: Applied Physics, 47 (14), 1-10. (doi:10.1088/0022-3727/47/14/145102).

Record type: Article

Abstract

This work exploits the switching dynamics of nanoscale Resistive Random Access Memory (ReRAM) cells with particular emphasis on the origin of the observed variability when consecutively cycled/programmed at distinct memory states. It is demonstrated that this variance is a common feature of all ReRAM elements and is ascribed to the formation and rupture of conductive filaments that expand across the active core, independently of the material employed as the active switching core, the causal physical switching mechanism, the switching mode (bipolar/unipolar) or even the unit cells’ dimensions. Our hypothesis is supported through both experimental and theoretical studies on TiO2 and In2O3:SnO2 (ITO) based ReRAM cells while programmed at three distinct resistive states. Our prototypes employed TiO2 or ITO active cores over 5×5 µm2 and 100x100 µm2 cells’ areas, with all tested devices demonstrating both unipolar and bipolar switching modalities. In the case of TiO2-based cells, the underlying switching mechanism is based on the non-uniform displacement of ionic species that foster the formation of conductive filaments. On the other hand, the resistive switching observed in the ITO-based devices is considered to be due to a phase change mechanism. The selected experimental parameters allowed us to demonstrate that the observed programming variance is a common feature of all ReRAM devices, proving that its origin is dependent upon randomly oriented local disorders within the active core that have a substantial impact in the overall state variance particularly for high-resistive states.

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Published date: 20 March 2014
Organisations: Nanoelectronics and Nanotechnology

Identifiers

Local EPrints ID: 362461
URI: https://eprints.soton.ac.uk/id/eprint/362461
ISSN: 0022-3727
PURE UUID: 2e58252a-0508-4ab2-986e-0f4908916d25
ORCID for T. Prodromakis: ORCID iD orcid.org/0000-0002-6267-6909

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Date deposited: 25 Feb 2014 10:27
Last modified: 06 Jul 2018 00:29

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Contributors

Author: I. Salaoru
Author: A. Khiat
Author: R. Berdan
Author: L. Quingjian
Author: C. Papavassiliou
Author: T. Prodromakis ORCID iD

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