Memristive switching mechanism for metal/oxide/metal nanodevices


Nanoscale metal/oxide/metal switches have the potential to transform the market for nonvolatile memory and could lead to novel forms of computing. However, progress has been delayed by difficulties in understanding and controlling the coupled electronic and ionic phenomena that dominate the behaviour of nanoscale oxide devices. An analytic theory of the ‘memristor’ (memory-resistor) was first developed from fundamental symmetry arguments in 1971, and we recently showed that memristor behaviour can naturally explain such coupled electron–ion dynamics. Here we provide experimental evidence to support this general model of memristive electrical switching in oxide systems. We have built micro- and nanoscale TiO2 junction devices with platinum electrodes that exhibit fast bipolar nonvolatile switching. We demonstrate that switching involves changes to the electronic barrier at the Pt/TiO2 interface due to the drift of positively charged oxygen vacancies under an applied electric field. Vacancy drift towards the interface creates conducting channels that shunt, or short-circuit, the electronic barrier to switch ON. The drift of vacancies away from the interface annilihilates such channels, recovering the electronic barrier to switch OFF. Using this model we have built TiO2 crosspoints with engineered oxygen vacancy profiles that predictively control the switching polarity and conductance.

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Figure 1: Bipolar reversible and nonvolatile switching of nanoscale TiO2−x devices.
Figure 2: Junctions on single-crystal TiO2 show the role of the interfaces in determining the electrical behaviour.
Figure 3: Switching is local and occurs at the Pt/TiO2 interface.
Figure 4: Thin-film TiO2−x devices with controlled oxygen vacancy profiles verify the switching mechanism.


  1. 1

    Vogel, E. M. Technology and metrology of new electronic materials and devices. Nature Nanotech. 2, 25–32 (2007).

    Article  Google Scholar 

  2. 2

    Szot, K. et al. Switching the electrical resistance of individual dislocations in single-crystalline SrTiO3 . Nature Mater. 5, 312–320 (2006).

    Article  Google Scholar 

  3. 3

    Aono, M. et al. Quantized conductance atomic switch. Nature 433, 47–50 (2005).

    Article  Google Scholar 

  4. 4

    Moore, G. E. Cramming more components onto integrated circuits. Electronics 38, 114–116 (1965).

    Google Scholar 

  5. 5

    Mead, C. Analog VLSI and Neural Systems (Addison-Wesley, Reading, MA, 1989).

    Google Scholar 

  6. 6

    Boahen, K. Neuromorphic microchips. Sci. Am. 292, 56–63 (2005).

    Article  Google Scholar 

  7. 7

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

    Article  Google Scholar 

  8. 8

    Watanabe, Y. et al. Current-driven insulator–conductor transition and nonvolatile memory in chromium-doped SrTiO3 single crystals. Appl. Phys. Lett. 78, 3738–3740 (2001).

    Article  Google Scholar 

  9. 9

    Chopra, K. L. Avalanche-induced negative resistance in thin oxide films. J. Appl. Phys. 36, 184–187 (1965).

    Article  Google Scholar 

  10. 10

    Simmons, J. G. & Verderber, R. R. New conduction and reversible memory phenomena in thin insulating films. Proc. R. Soc. Lond. A 301, 77–102 (1967).

    Article  Google Scholar 

  11. 11

    Rozenberg, M. J., Inoue, I. H. & Sánchez, M. J. Nonvolatile memory with multilevel switching: a basic model. Phys. Rev. Lett. 92, 178302 (2004).

    Article  Google Scholar 

  12. 12

    Chen, X., Wu, N., Strozier, J. & Ignatiev, A. Spatially extended nature of resistive switching in perovskite oxide thin films. Appl. Phys. Lett. 89, 063507 (2006).

    Article  Google Scholar 

  13. 13

    Fors, R., Khartsev, S. I. & Grishin, A. M. Giant resistance switching in metal–insulator–manganite junctions: evidence for Mott transition. Phys. Rev. B 71, 045305 (2005).

    Article  Google Scholar 

  14. 14

    Rohde, C. et al. Identification of a determining parameter for resistive switching of TiO2 thin films. Appl. Phys. Lett. 86, 262907 (2005).

    Article  Google Scholar 

  15. 15

    Liu, S. Q.,Wu, N. J. & Ignatiev, A. Electric-pulse-induced reversible resistance change effect in magnetoresistive films. Appl. Phys. Lett. 76, 2749–2751 (2000).

    Article  Google Scholar 

  16. 16

    Nian, Y. B., Strozier, J., Wu, N. J., Chen, X. & Ignatiev, A. Evidence for an oxygen diffusion model for the electric pulse induced resistance change effect in transition-metal oxides. Phys. Rev. Lett. 98, 146403 (2007).

    Article  Google Scholar 

  17. 17

    Jeon, S. H., Park, B. H., Lee, J., Lee, B. & Han, S. First-principles modeling of resistance switching in perovskite oxide material. Appl. Phys. Lett. 89, 042904 (2006).

    Article  Google Scholar 

  18. 18

    Jameson, J. R. et al. Field-programmable rectification in rutile TiO2 crystals. Appl. Phys. Lett. 91, 112101 (2007).

    Article  Google Scholar 

  19. 19

    Sawa, A., Fujii, T., Kawasaki, M. & Tokura, Y. Hysteretic current–voltage characteristics and resistance switching at a rectifying Ti/Pr0.7Ca0.3MnO3 interface. Appl. Phys. Lett. 85, 4073–4075 (2004).

    Article  Google Scholar 

  20. 20

    Tsui, S., Wang, Y. Q., Xue, Y. Y. & Chu, C. W. Mechanism and scalability in resistive switching of metal-Pr0.7Ca0.3MnO3 interface. Appl. Phys. Lett. 89, 123502 (2006).

    Article  Google Scholar 

  21. 21

    Baikalov, A. et al. Field-driven hysteretic and reversible resistive switch at the Ag–Pr0.7Ca0.3MnO3 interface. Appl. Phys. Lett. 83, 957–959 (2003).

    Article  Google Scholar 

  22. 22

    Kim, K. M., Choi, B. J., Shin, Y. C., Choi, S. & Hwang, C. S. Anode-interface localized filamentary mechanism in resistive switching of TiO2 thin films. Appl. Phys. Lett. 91, 012907 (2007).

    Article  Google Scholar 

  23. 23

    Fujii, T., Kawasaki, M., Sawa, A. & Akoh, H. Hysteretic current–voltage characteristics and resistance switching at an epitaxial oxide Schottky junction SrRuO3/SrTi0.99Nb0.01O3 . Appl. Phys. Lett. 86, 012107 (2005).

    Article  Google Scholar 

  24. 24

    Tsunoda, K. et al. Bipolar resistive switching in polycrystalline TiO2 films. Appl. Phys. Lett. 90, 113501 (2007).

    Article  Google Scholar 

  25. 25

    Lee, D. et al. Resistance switching of copper doped MoOx films for nonvolatile memory applications. Appl. Phys. Lett. 90, 122104 (2007).

    Article  Google Scholar 

  26. 26

    Jung, G. Y. et al. Fabrication of a 34 × 34 crossbar structure at 50 nm half-pitch by UV-based nanoimprint lithography. Nano Lett. 4, 1225–1229 (2004).

    Article  Google Scholar 

  27. 27

    Jung, G. Y. et al. Circuit fabrication at 17 nm half-pitch by nanoimprint lithography. Nano Lett. 6, 351–354 (2006).

    Article  Google Scholar 

  28. 28

    Szot, K., Speier, W. & Eberhardt, W. Microscopic nature of the metal to insulator phase transition induced through electroreduction in single-crystal KNbO3 . Appl. Phys. Lett. 60, 1190–1192 (1992).

    Article  Google Scholar 

  29. 29

    Knauth, P. & Tuller, H. L. Electrical and defect thermodynamic properties of nanocrystalline titanium dioxide. J. Appl. Phys. 85, 897–902 (1999).

    Article  Google Scholar 

  30. 30

    Rhoderick, E. H. & Williams, R. H. Metal–Semiconductor Contacts, 2nd edn (Oxford Science Publications, Oxford 1988).

    Google Scholar 

  31. 31

    Weibel, A., Bouchet, R. & Knauth, P. Electrical properties and defect chemistry of anatase (TiO2). Solid State Ionics 177, 229–236 (2006).

    Article  Google Scholar 

  32. 32

    Choi, B. J. et al. Resistive switching mechanism of TiO2 thin films grown by atomic-layer deposition. J. Appl. Phys. 98, 033715 (2005).

    Article  Google Scholar 

  33. 33

    Chua, L. O. Memristor — missing circuit element. IEEE Trans. Circuit Theory CT-18, 507–519 (1971).

    Article  Google Scholar 

  34. 34

    Strukov, D. B., Snider, G. S., Stewart, D. R. & Williams, R. S. The missing memristor found. Nature 453, 80–83 (2008).

    Article  Google Scholar 

  35. 35

    Ohdomari, I. & Tu, K. N. Parallel silicide contacts. J. Appl. Phys. 51, 3735–3739 (1980).

    Article  Google Scholar 

  36. 36

    Tung, R. T. Electron transport at metal–semiconductor interfaces: General theory. Phys. Rev. B 45, 13509–13523 (1992).

    Article  Google Scholar 

  37. 37

    Talin, A. A., Williams, R. S., Morgan, B. A., Ring, K. M. & Kavanagh, K. L. Nanometer-resolved spatial variations in the Schottky barrier height of a Au/n-type GaAs diode. Phys. Rev. B 49, 16474–16479 (1994).

    Article  Google Scholar 

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The authors are grateful to HP colleagues W. Tong, J. Borghetti, Feng Miao and Zhiyong Li for valuable assistance with experiments, and D. Strukov and P. Kuekes for insightful discussions about the TiO2 switching mechanisms. This research was supported in part by Intelligence Advanced Research Projects Activity.

Author information




J.Y. and D.S. conceived and designed the experiments. J.Y. performed the experiments. J.Y., M.P., D.S. and R.W. analysed the data. D.O. and X.L. contributed materials/analysis tools. J.Y., D.S. and R.W. co-wrote the paper.

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Correspondence to Duncan R. Stewart.

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Yang, J., Pickett, M., Li, X. et al. Memristive switching mechanism for metal/oxide/metal nanodevices. Nature Nanotech 3, 429–433 (2008).

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