Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Design and fabrication of memory devices based on nanoscale polyoxometalate clusters

Abstract

Flash memory devices—that is, non-volatile computer storage media that can be electrically erased and reprogrammed—are vital for portable electronics, but the scaling down of metal–oxide–semiconductor (MOS) flash memory to sizes of below ten nanometres per data cell presents challenges. Molecules have been proposed to replace MOS flash memory1, but they suffer from low electrical conductivity, high resistance, low device yield, and finite thermal stability, limiting their integration into current MOS technologies. Although great advances have been made in the pursuit of molecule-based flash memory2, there are a number of significant barriers to the realization of devices using conventional MOS technologies3,4,5,6,7. Here we show that core–shell polyoxometalate (POM) molecules8 can act as candidate storage nodes for MOS flash memory. Realistic, industry-standard device simulations validate our approach at the nanometre scale, where the device performance is determined mainly by the number of molecules in the storage media and not by their position. To exploit the nature of the core–shell POM clusters, we show, at both the molecular and device level, that embedding [(Se(iv)O3)2]4− as an oxidizable dopant in the cluster core allows the oxidation of the molecule to a [Se(v)2O6]2− moiety containing a {Se(v)–Se(v)} bond (where curly brackets indicate a moiety, not a molecule) and reveals a new 5+ oxidation state for selenium. This new oxidation state can be observed at the device level, resulting in a new type of memory, which we call ‘write-once-erase’. Taken together, these results show that POMs have the potential to be used as a realistic nanoscale flash memory. Also, the configuration of the doped POM core may lead to new types of electrical behaviour9,10,11. This work suggests a route to the practical integration of configurable molecules in MOS technologies as the lithographic scales approach the molecular limit12.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Structure and electrochemical properties of compound 1a.
Figure 2: Image of the flash memory device and the drain current behaviour with an applied voltage to the control gate.
Figure 3: Scheme depicting the formation of the Se(v)–Se(v) bond within the cluster cage.
Figure 4: The write-once-erase device.
Figure 5: Device modelling simulations of compounds 1a and 2.

Accession codes

Data deposits

Atomic coordinates for the reported crystal structures have been deposited with the Cambridge Structural Database under the accession codes 997534 (compound precursor), 997535 (compound 1a), 997536 (compound 1c) and 997537 (compound 1d), and full synthetic, electrochemical, device theory, device modelling and electronic device data is given in the Supplementary Information.

References

  1. Joachim, C., Gimzewski, J. K. & Aviram, A. Electronics using hybrid-molecular and mono-molecular devices. Nature 408, 541–548 (2000)

    Article  ADS  CAS  Google Scholar 

  2. Shaw, J. T. et al. Integration of self-assembled redox molecules in flash memories. IEEE Trans. Electron. Dev. 58, 826–834 (2011)

    Article  ADS  CAS  Google Scholar 

  3. Zhu, H. et al. Non-volatile memory with self-assembled ferrocene charge trapping layer. Appl. Phys. Lett. 103, 53102–53104 (2013)

    Article  Google Scholar 

  4. Chen, P.-C., Shen, G. & Zhou, C. Chemical sensors and electronic noses based on 1-D metal oxide nanostructures. IEEE Trans. Nanotechnol. 7, 668–682 (2008)

    Article  ADS  Google Scholar 

  5. Shaw, J., Xu, Q., Rajwade, S., Hou, T.-H. & Kan, E. C. Redox molecules for a resonant tunneling barrier in nonvolatile memory. IEEE Trans. Electron. Dev. 59, 1189–1198 (2012)

    Article  ADS  CAS  Google Scholar 

  6. Seol, M.-L., Choi, S.-J., Kim, C.-H., Moon, D.-I. & Choi, Y.-K. Porphyrin-silicon hybrid field-effect transistor with individually addressable top-gate structure. ACS Nano 6, 183–189 (2012)

    Article  CAS  Google Scholar 

  7. Tans, S. J., Verschueren, A. R. M. & Dekker, C. Room-temperature transistor based on a single carbon nanotube. Nature 393, 49–52 (1998)

    ADS  CAS  Google Scholar 

  8. Long, D. L. & Cronin, L. Towards polyoxometalate integrated nanosystems. Chem. Eur. J. 12, 3698–3706 (2006)

    Article  CAS  Google Scholar 

  9. Lehmann, J., Gaita-Arino, A., Coronado, E. & Loss, D. Spin qubits with electrically gated polyoxometalate molecules. Nature Nanotechnol. 2, 312–317 (2007)

    Article  ADS  CAS  Google Scholar 

  10. Li, H. et al. Layer-by-layer assembly and UV photoreduction of graphene–polyoxometalate composite films for electronics. J. Am. Chem. Soc. 133, 9423–9429 (2011)

    Article  CAS  Google Scholar 

  11. Fleming, L. et al. Surface-mediated reversible electron transfer reactions within a molecular metal oxide nano-cage. Nature Nanotechnol. 3, 229–233 (2008)

    Article  CAS  Google Scholar 

  12. Bonfiglio, V. & Iannaccone, G. Sensitivity-based investigation of threshold voltage variability in 32-nm flash memory cells and MOSFETs. Solid-State Electron. 84, 127–131 (2013)

    Article  ADS  CAS  Google Scholar 

  13. Vilà-Nadal, L. et al. Polyoxometalate {W18O56XO6} clusters with embedded redox-active main-group templates as localized inner-cluster radicals. Angew. Chem. Int. Ed. 52, 9695–9699 (2013)

    Article  Google Scholar 

  14. Vilà-Nadal, L. et al. Towards polyoxometalate-cluster-based nano-electronics. Chem. Eur. J. 19, 16502–16511 (2013)

    Article  Google Scholar 

  15. Gallon, C. et al. Electrical analysis of mechanical stress induced by STI in short MOSFETs using externally applied stress. IEEE Trans. Electron. Dev. 51, 1254–1261 (2004)

    Article  ADS  CAS  Google Scholar 

  16. Simmons, J. G. Generalized formula for the electric tunnel effect between similar electrodes separated by a thin insulating film. J. Appl. Phys. 34, 1793–1803 (1963)

    Article  ADS  Google Scholar 

  17. Fowler, R. H. & Nordheim, L. Electron emission in intense electric fields. Proc. R. Soc. Lond. A 119, 173–181 (1928)

    Article  ADS  CAS  Google Scholar 

Download references

Acknowledgements

We gratefully acknowledge financial support from the EPSRC for funding (grants EP/H024107/1, EP/I033459/1 and EP/J015156/1), the COST Action CM1203 (PoCheMoN), the Royal Society Wolfson Foundation for a Merit Award, and the University of Glasgow. V.P.G. and A.A. thank S. Markov and S. M. Amoroso for discussions.

Author information

Authors and Affiliations

Authors

Contributions

L.C. conceived the idea, designed the project and coordinated the efforts of the research team. J.Y. synthesised the clusters and conducted the first electrochemistry experiments and structural characterization with D.-L.L. H.N.M., C.B., L.V.-N., and L.C. helped to characterize the physical properties of the clusters. C.B. did the electron paramagnetic resonance, electrochemistry and spectroscopic measurements. L.V.-N., L.C., V.P.G. and A.A. designed the theory-to-modelling strategy. L.V.-N., with J.M.P., did the DFT calculations. V.P.G. and A.A. did the device simulation. R.H.P. and N.G. fabricated and characterized the electrode arrays, produced the devices, made the measurements and characterized the data. M.M.M. and D.J.P. designed the nanowire arrays and M.M.M. fabricated the electrodes and optimized the data with D.J.P., who helped analyse the results. C.B., L.V.-N. and L.C. co-wrote the paper with input from all the authors.

Corresponding author

Correspondence to Leroy Cronin.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Text and Data, Supplementary Figures 1-14, Supplementary Tables 1-8 and Supplementary References. (PDF 3238 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Busche, C., Vilà-Nadal, L., Yan, J. et al. Design and fabrication of memory devices based on nanoscale polyoxometalate clusters. Nature 515, 545–549 (2014). https://doi.org/10.1038/nature13951

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature13951

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing