The memristor1,2 is a promising building block for next-generation non-volatile memory3, artificial neural networks4,5,6,7 and bio-inspired computing systems8,9. Organizing small memristors into high-density crossbar arrays is critical to meet the ever-growing demands in high-capacity and low-energy consumption, but this is challenging because of difficulties in making highly ordered conductive nanoelectrodes. Carbon nanotubes, graphene nanoribbons and dopant nanowires have potential as electrodes for discrete nanodevices10,11,12,13,14, but unfortunately these are difficult to pack into ordered arrays. Transfer printing, on the other hand, is effective in generating dense electrode arrays15 but has yet to prove suitable for making fully random accessible crossbars. All the aforementioned electrodes have dramatically increased resistance at the nanoscale16,17,18, imposing a significant barrier to their adoption in operational circuits. Here we demonstrate memristor crossbar arrays with a 2-nm feature size and a single-layer density up to 4.5 terabits per square inch, comparable to the information density achieved using three-dimensional stacking in state-of-the-art 64-layer and multilevel 3D-NAND flash memory19. Memristors in the arrays switch with tens of nanoamperes electric current with nonlinear behaviour. The densely packed crossbar arrays of individually accessible, extremely small functional memristors provide a power-efficient solution for information storage and processing.

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This work was supported by the US National Science Foundation (NSF) (ECCS-1253073). Part of the device fabrication work was conducted in the clean room of the Center for Hierarchical Manufacturing (CHM), an NSF Nanoscale Science and Engineering Center (NSEC) located at the University of Massachusetts Amherst. The TEM work used resources of the Center for Functional Nanomaterials, which is a US DOE Office of Science Facility, at Brookhaven National Laboratory under contract no. DE-SC0012704.

Author information


  1. Department of Electrical and Computer Engineering, University of Massachusetts, Amherst, Massachusetts, USA

    • Shuang Pi
    • , Can Li
    • , Hao Jiang
    • , J. Joshua Yang
    •  & Qiangfei Xia
  2. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York, USA

    • Weiwei Xia
    •  & Huolin Xin


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Q.X. conceived and designed the experiments. S.P. fabricated and measured the circuits. C.L., W.X. and H.X. conducted the focused ion beam and TEM characterization. S.P., Q.X., H.J. and J.J.Y. analysed the data. Q.X. and S.P. wrote the manuscript. All authors commented and approved the manuscript.

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The authors declare no competing interests.

Corresponding author

Correspondence to Qiangfei Xia.

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  1. Supplementary Information

    Supplementary Figures 1–22, Supplementary Notes 1–6, Supplementary References

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