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Robust resistive memory devices using solution-processable metal-coordinated azo aromatics

A Corrigendum to this article was published on 19 December 2017

This article has been updated

Abstract

Non-volatile memories will play a decisive role in the next generation of digital technology. Flash memories are currently the key player in the field, yet they fail to meet the commercial demands of scalability and endurance. Resistive memory devices, and in particular memories based on low-cost, solution-processable and chemically tunable organic materials, are promising alternatives explored by the industry. However, to date, they have been lacking the performance and mechanistic understanding required for commercial translation. Here we report a resistive memory device based on a spin-coated active layer of a transition-metal complex, which shows high reproducibility (350 devices), fast switching (≤30 ns), excellent endurance (1012 cycles), stability (>106 s) and scalability (down to 60 nm2). In situ Raman and ultraviolet–visible spectroscopy alongside spectroelectrochemistry and quantum chemical calculations demonstrate that the redox state of the ligands determines the switching states of the device whereas the counterions control the hysteresis. This insight may accelerate the technological deployment of organic resistive memories.

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Figure 1: Structure and device characteristics.
Figure 2: Device statistics.
Figure 3: Device performance.
Figure 4: Detection of redox states by in situ spectroscopy.
Figure 5: Correlation between Raman peaks and film conductance.
Figure 6: Effect of counterion.

Change history

  • 04 December 2017

    In the version of this Article originally published, the x-axis units of Fig. 3a were incorrectly given as ms, and should have read μs. This has now been corrected. Two places in the text also needed amending to reflect this change: the penultimate sentence of Fig. 3c,d caption now starts 'Microsecond pulses are used', and the penultimate sentence of the second paragraph of 'Device performance' has been changed to begin 'Device A was measured continuously over 230 days with microsecond write–read pulses'. All have now been corrected in the online versions of the Article.

References

  1. 1

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

    CAS  Article  Google Scholar 

  2. 2

    Yang, J. J., Strukov, D. B. & Stewart, D. R. Memristive devices for computing. Nat. Nanotech. 8, 13–24 (2013).

    CAS  Google Scholar 

  3. 3

    Prezioso, M. et al. Training and operation of an integrated neuromorphic network based on metal-oxide memristors. Nature 521, 61–64 (2015).

    CAS  Google Scholar 

  4. 4

    Kim, K. M. et al. Voltage divider effect for the improvement of variability and endurance of TaOx memristor. Sci. Rep. 6, 20085 (2016).

    CAS  Google Scholar 

  5. 5

    Wedig, A. et al. Nanoscale cation motion in TaO(x), HfO(x) and TiO(x) memristive systems. Nat. Nanotech. 11, 67–74 (2016).

    CAS  Google Scholar 

  6. 6

    Lee, M.-J. et al. A fast, high-endurance and scalable non-volatile memory device made from asymmetric Ta2O5−x/TaO2−x bilayer structures. Nat. Mater. 10, 625–630 (2011).

    CAS  Google Scholar 

  7. 7

    Sangwan, V. K. et al. Gate-tunable memristive phenomena mediated by grain boundaries in single-layer MoS2 . Nat. Nanotech. 10, 403–406 (2015).

    CAS  Google Scholar 

  8. 8

    Yoshida, M., Suzuki, R., Zhang, Y., Nakano, M. & Iwasa, Y. Memristive phase switching in two-dimensional 1T-TaS2 crystals. Sci. Adv. 1, e1500606 (2015).

    Google Scholar 

  9. 9

    Lin, W. P., Liu, S. J., Gong, T., Zhao, Q. & Huang, W. Polymer-based resistive memory materials and devices. Adv. Mater. 26, 570–606 (2014).

    CAS  Google Scholar 

  10. 10

    Hu, B. et al. Inorganic–organic hybrid polymer with multiple redox for high-density data storage. Chem. Sci. 5, 3404–3408 (2014).

    CAS  Google Scholar 

  11. 11

    Bandyopadhyay, A., Sahu, S. & Higuchi, M. Tuning of nonvolatile bipolar memristive switching in Co (III) polymer with an extended azo aromatic ligand. J. Am. Chem. Soc. 133, 1168–1171 (2011).

    CAS  Google Scholar 

  12. 12

    Cho, B., Song, S., Ji, Y., Kim, T. W. & Lee, T. Organic resistive memory devices: performance enhancement, integration, and advanced architectures. Adv. Funct. Mater. 21, 2806–2829 (2011).

    CAS  Google Scholar 

  13. 13

    Miao, S. et al. Molecular length adjustment for organic azo-based nonvolatile ternary memory devices. J. Mater. Chem. 22, 16582–16589 (2012).

    CAS  Google Scholar 

  14. 14

    Miao, S. et al. Tailoring of molecular planarity to reduce charge injection barrier for high-performance small-molecule-based ternary memory device with low threshold voltage. Adv. Mater. 24, 6210–6215 (2012).

    CAS  Google Scholar 

  15. 15

    Paul, N. D., Rana, U., Goswami, S., Mondal, T. K. & Goswami, S. Azo anion radical complex of rhodium as a molecular memory switching device: isolation, characterization, and evaluation of current-voltage characteristics. J. Am. Chem. Soc. 134, 6520–6523 (2012).

    CAS  Google Scholar 

  16. 16

    Gilbert, N., Zhang, Y., Dinh, J., Calhoun, B. & Hollmer, S. A 0.6 V 8 pJ/write non-volatile CBRAM macro embedded in a body sensor node for ultra low energy applications. VLSI Circuits (VLSIC), 2013 Symp. C204–C205 (IEEE, 2013).

    Google Scholar 

  17. 17

    Lin, W. P., Liu, S. J., Gong, T., Zhao, Q. & Huang, W. Polymer—based resistive memory materials and devices. Adv. Mater. 26, 570–606 (2014).

    CAS  Google Scholar 

  18. 18

    Forrest, S. R. The path to ubiquitous and low-cost organic electronic appliances on plastic. Nature 428, 911–918 (2004).

    CAS  Google Scholar 

  19. 19

    Xiang, D., Wang, X., Jia, C., Lee, T. & Guo, X. Molecular-scale electronics: from concept to function. Chem. Rev. 116, 4318–4440 (2016).

    CAS  Google Scholar 

  20. 20

    Nijhuis, C. A., Reus, W. F. & Whitesides, G. M. Molecular rectification in metal–SAM–metal oxide–metal junctions. J. Am. Chem. Soc. 131, 17814–17827 (2009).

    CAS  Google Scholar 

  21. 21

    Zhao, C., Zhao, C. Z., Taylor, S. & Chalker, P. R. Review on non-volatile memory with high-k dielectrics: flash for generation beyond 32 nm. Materials 7, 5117–5145 (2014).

    Google Scholar 

  22. 22

    Miao, S. et al. Tailoring of molecular planarity to reduce charge injection barrier for high-performance small-molecule-based ternary memory device with low threshold voltage. Adv. Mater. 24, 6210–6215 (2012).

    CAS  Google Scholar 

  23. 23

    Gu, P. Y. et al. Synthesis, characterization, and nonvolatile ternary memory behavior of a larger heteroacene with nine linearly fused rings and two different heteroatoms. J. Am. Chem. Soc. 135, 14086–14089 (2013).

    CAS  Google Scholar 

  24. 24

    Goswami, S., Mukherjee, R. & Chakravorty, A. Chemistry of ruthenium. 12. Reactions of bidentate ligands with diaquabis [2-(arylazo) pyridine] ruthenium (II) cation. Stereoretentive synthesis of tris chelates and their characterization: metal oxidation, ligand reduction, and spectroelectrochemical correlation. Inor. Chem. 22, 2825–2832 (1983).

    CAS  Google Scholar 

  25. 25

    Ielmini, D. & Waser, R. Resistive Switching: From Fundamentals of Nanoionic Redox Processes to Memristive Device Applications (John Wiley, 2015).

    Google Scholar 

  26. 26

    Padma, N., Betty, C. A., Samanta, S. & Nigam, A. Tunable switching characteristics of low operating voltage organic bistable memory devices based on gold nanoparticles and copper phthalocyanine thin films. J. Phys. Chem. C 121, 5768–5778 (2017).

    CAS  Google Scholar 

  27. 27

    Kim, W. T., Jung, J. H., Kim, T. W. & Son, D. I. Current bistability and carrier transport mechanisms of organic bistable devices based on hybrid Ag nanoparticle-polymethyl methacrylate polymer nanocomposites. Appl. Phys. Lett. 96, 253301 (2010).

    Google Scholar 

  28. 28

    Choi, B. J., Chen, A. B., Yang, X. & Chen, I. W. Purely electronic switching with high uniformity, resistance tunability, and good retention in Pt—dispersed SiO2 thin films for ReRAM. Adv. Mater. 23, 3847–3852 (2011).

    CAS  Google Scholar 

  29. 29

    Zou, X. et al. Charge trapping-detrapping induced resistive switching in Ba0.7Sr0.3TiO3 . AIP Adv. 2, 032166 (2012).

    Google Scholar 

  30. 30

    Han, H., Kim, Y., Alexe, M., Hesse, D. & Lee, W. Nanostructured ferroelectrics: fabrication and structure–property relations. Adv. Mater. 23, 4599–4613 (2011).

    CAS  Google Scholar 

  31. 31

    Au, V. K.-M., Wu, D. & Yam, V. W.-W. Organic memory devices based on a bis-cyclometalated alkynylgold (III) complex. J. Am. Chem. Soc. 137, 4654–4657 (2015).

    CAS  Google Scholar 

  32. 32

    Hong, E. Y.-H., Poon, C.-T. & Yam, V. W.-W. A phosphole oxide-containing organogold (III) complex for solution-processable resistive memory devices with ternary memory performances. J. Am. Chem. Soc. 138, 6368–6371 (2016).

    CAS  Google Scholar 

  33. 33

    Strachan, J. P., Torrezan, A. C., Medeiros-Ribeiro, G. & Williams, R. S. Measuring the switching dynamics and energy efficiency of tantalum oxide memristors. Nanotechnology 22, 505402 (2011).

    Google Scholar 

  34. 34

    Liu, Z., Yasseri, A. A., Lindsey, J. S. & Bocian, D. F. Molecular memories that survive silicon device processing and real-world operation. Science 302, 1543–1545 (2003).

    CAS  Google Scholar 

  35. 35

    Lindsey, J. S. & Bocian, D. F. Molecules for charge-based information storage. Acc. Chem. Res. 44, 638–650 (2011).

    CAS  Google Scholar 

  36. 36

    Liu, Y.-C., Hwang, B.-J., Jian, W.-J. & Santhanam, R. In situ cyclic voltammetry-surface-enhanced Raman spectroscopy: studies on the doping–undoping of polypyrrole film. Thin Solid Films 374, 85–91 (2000).

    CAS  Google Scholar 

  37. 37

    Kaliginedi, V. et al. Layer-by-layer grown scalable redox-active ruthenium-based molecular multilayer thin films for electrochemical applications and beyond. Nanoscale 7, 17685–17692 (2015).

    CAS  Google Scholar 

  38. 38

    Wu, H. L., Huff, L. A. & Gewirth, A. A. In situ Raman spectroscopy of sulfur speciation in lithium-sulfur batteries. ACS Appl. Mater Interfaces 7, 1709–1719 (2015).

    CAS  Google Scholar 

  39. 39

    Gu, M. & Lu, H. P. Raman mode-selective spectroscopic imaging of coenzyme and enzyme redox states. J. Raman Spectrosc. 47, 801–807 (2016).

    CAS  Google Scholar 

  40. 40

    van Reenen, S., Kemerink, M. & Snaith, H. J. Modeling anomalous hysteresis in perovskite solar cells. J. Phys. Chem. Lett. 6, 3808–3814 (2015).

    CAS  Google Scholar 

  41. 41

    Niiyama, T., Okushima, T., Ikeda, K. S. & Shimizu, Y. Size dependence of vacancy migration energy in ionic nano particles: a potential energy landscape perspective. Chem. Phys. Lett. 654, 52–57 (2016).

    CAS  Google Scholar 

  42. 42

    Gao, P. et al. Revealing the role of defects in ferroelectric switching with atomic resolution. Nat. Commun. 2, 591 (2011).

    Google Scholar 

  43. 43

    Samanta, S., Ghosh, P. & Goswami, S. Recent advances on the chemistry of transition metal complexes of 2-(arylazo) pyridines and its arylamino derivatives. Dalton Trans. 41, 2213–2226 (2012).

    CAS  Google Scholar 

  44. 44

    Seo, K., Konchenko, A. V., Lee, J., Bang, G. S. & Lee, H. Molecular conductance switch-on of single ruthenium complex molecules. J. Am. Chem. Soc. 130, 2553–2559 (2008).

    CAS  Google Scholar 

  45. 45

    Lee, J. et al. Nitronyl nitroxide radicals as organic memory elements with both n- and p-type properties. Angew. Chem. Int. Ed. 50, 4414–4418 (2011).

    CAS  Google Scholar 

  46. 46

    Campbell, N., Henderson, A. W. & Taylor, D. 257. Geometrical isomerism of azo-compounds. J. Chem. Soc. 0, 1281–1285 (1953).

    CAS  Google Scholar 

  47. 47

    Ghosh, P. et al. Introducing a New Azoaromatic Pincer Ligand. Isolation and characterization of redox events in its ferrous complexes. Inor. Chem. 53, 4678–4686 (2014).

    CAS  Google Scholar 

  48. 48

    Lin, J. C. et al. Control of the metal–insulator transition at complex oxide heterointerfaces through visible light. Adv. Mater. 28, 764–770 (2016).

    CAS  Google Scholar 

  49. 49

    Yuan, Y. et al. Ultra-high mobility transparent organic thin film transistors grown by an off-centre spin-coating method. Nat. Commun. 5, 3005 (2014).

    Google Scholar 

  50. 50

    Mayer, M. SIMNRA, a simulation program for the analysis of NRA, RBS and ERDA. The 15th Int. Conf. Appl. Accelerators Res. Industry 541–544 (AIP Publishing, 1999).

    Google Scholar 

  51. 51

    Feldman, L. C. & Mayer, J. W. Fundamentals of Surface and Thin Film Analysis (North-Holland, 1986).

    Google Scholar 

  52. 52

    Becke, A. D. Density-functional exchange-energy approximation with correct asymptotic behavior. Phys. Rev. A 38, 3098 (1988).

    CAS  Google Scholar 

  53. 53

    Weigend, F. & Ahlrichs, R. Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: design and assessment of accuracy. Phys. Chem. Chem. Phys. 7, 3297–3305 (2005).

    CAS  Google Scholar 

  54. 54

    Frisch, M. J. et al. Gaussian 09, Revision A. 1 (Gaussian, 2009).

    Google Scholar 

Download references

Acknowledgements

T.V. would like to acknowledge support from the National Research Foundation under Competitive Research Program (NRF2015NRF_CRP001_015) and (NRF-CRP10-2012-02). Sreebrata Goswami would like to acknowledge the financial support of SERB, India through grants SR/S2/JCB-09/2011 and EMR/2014/000520. V.S.B. acknowledges supercomputing time from NERSC and from the Yale High Performance Computing Center and support by the Air Force Office of Scientific Research (AFOSR) through grant #FA9550-13-1-0020. Sreetosh Goswami is supported by NUS Graduate School for Integrative Science and Engineering (NGS). A.J.M. is supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1122492. C.A.N. acknowledges the Minister of Education (MOE) for supporting this research under award No. MOE2015-T2-1-050. J.M. is supported by the National Research Foundation, Prime Minister’s Office, Singapore under its Medium sized centre programme. We would like to thank Centre of Integrated Circuit and Failure Analysis (CICFAR) for providing the AFM facility. We thank S. B. Ogale, M. Reed and C. Jingsheng for their comments on the work and the manuscript. Sreebrata Goswami thanks A. Llobet, ICIQ for spectroelectrochemical data.

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Sreetosh Goswami devised the project, fabricated the devices, and did the J(V) measurements and the in situ spectroscopies. S.Saha helped Sreetosh Goswami with the in situ Raman measurement technique and data analysis. A.J.M. and S.H. built the theoretical models and performed the DFT calculations. S.P.R. and D.S. synthesized and characterized the compounds in solution. M.A. did the c-AFM measurements and analysis. A.P. did the AFM measurement and participated in discussions. Siddhartha Ghosh participated in J(V) measurement, analysis and strategic discussions. H.J., S.Sarkar helped Sreetosh Goswami. to fabricate NP devices. M.R.M. conducted the Rutherford Back Scattering (RBS) measurements. J.M. analysed the transport data and guided Sreetosh Goswami for experimental planning and data interpretation. C.A.N. provided guidance in experimental designs and understanding the phenomena. V.S.B. supervised the theoretical contributions. Sreebrata Goswami introduced the materials and supervised their synthesis and characterization. T.V. supervised the entire research programme. All the authors participated in manuscript writing.

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Correspondence to Sreebrata Goswami or Victor S. Batista or T. Venkatesan.

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Goswami, S., Matula, A., Rath, S. et al. Robust resistive memory devices using solution-processable metal-coordinated azo aromatics. Nature Mater 16, 1216–1224 (2017). https://doi.org/10.1038/nmat5009

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