Nanoionics-based resistive switching memories


Many metal–insulator–metal systems show electrically induced resistive switching effects and have therefore been proposed as the basis for future non-volatile memories. They combine the advantages of Flash and DRAM (dynamic random access memories) while avoiding their drawbacks, and they might be highly scalable. Here we propose a coarse-grained classification into primarily thermal, electrical or ion-migration-induced switching mechanisms. The ion-migration effects are coupled to redox processes which cause the change in resistance. They are subdivided into cation-migration cells, based on the electrochemical growth and dissolution of metallic filaments, and anion-migration cells, typically realized with transition metal oxides as the insulator, in which electronically conducting paths of sub-oxides are formed and removed by local redox processes. From this insight, we take a brief look into molecular switching systems. Finally, we discuss chip architecture and scaling issues.

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Figure 1: Classification of the switching characteristics in a voltage sweeping experiment.
Figure 2: Sketch of filamentary conduction in MIM structures.

© 1998 WILEY

Figure 3: Cross-section of a vertical type of MIM switch using Ag+ conducting solid electrolyte.

© 2005 IEEE

Figure 4: Scanning electron micrograph of an atomic switch and its operating mechanism32.
Figure 5: Three-terminal solid electrolyte switch.

© 2006 OUP

Figure 6: Multilevel switching in a Cr-doped SrZrO3 MIM cell operated at 77 K.

© 2000 AIP

Figure 7: Conductance of individual dislocations in SrTiO3.
Figure 8: Area-wide switching of an epitaxial 10-nm SrTiO3 thin film by C-AFM.

© 2007 WILEY

Figure 9: Filamentary structure induced by electroformation in an undoped SrTiO3 single crystal.
Figure 10: Infrared thermal micrograph of a planar Cr-doped SrTiO3 single-crystal cell.

© 2007 WILEY


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We thank J. G. Bednorz (IBM Research, Zurich), U-In Chung, I. G. Baek and S. O. Park (Samsung Electronics), Y. Zhang (Intel, Santa Clara), R. Bruchhaus (Qimonda, Munich), V. Zhirnov (SRC), and K. Szot and R. Dittmann (Research Center Jülich) for valuable comments.

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Correspondence to Rainer Waser.

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Waser, R., Aono, M. Nanoionics-based resistive switching memories. Nature Mater 6, 833–840 (2007).

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