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Nanotubular metal–insulator–metal capacitor arrays for energy storage

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Nanostructured devices have the potential to serve as the basis for next-generation energy systems that make use of densely packed interfaces and thin films1. One approach to making such devices is to build multilayer structures of large area inside the open volume of a nanostructured template. Here, we report the use of atomic layer deposition to fabricate arrays of metal–insulator–metal nanocapacitors in anodic aluminium oxide nanopores. These highly regular arrays have a capacitance per unit planar area of 10 µF cm−2 for 1-µm-thick anodic aluminium oxide and 100 µF cm−2 for 10-µm-thick anodic aluminium oxide, significantly exceeding previously reported values for metal–insulator–metal capacitors in porous templates2,3,4,5,6. It should be possible to scale devices fabricated with this approach to make viable energy storage systems that provide both high energy density and high power density.

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Figure 1: SEM cross-sections of MIM capacitors.
Figure 2: TEM of MIM capacitors.
Figure 3: Relationship between MIM nanotubular structure and the parameters used to calculate total capacitance.
Figure 4: Process sequence to prepare MIM capacitors.

Change history

  • 31 March 2009

    In the version of this Letter initially published online, the x axes in Fig. 2b were incorrect. This error has been corrected for all versions.


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This work was partially supported by the Laboratory for Physical Sciences and by the UMD-NSF-MRSEC under grant no. DMR 05-20471. The authors would like to thank E. Smela for providing facilities for anodic bonding of aluminium on glass, W.-A. Chiou for helpful discussions, the NanoCenter and the NISP Lab at the University of Maryland for materials processing and characterization, and MKS Instruments and Inficon Inc. for continued support of research activities in the laboratory.

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I.P. carried out anodic bonding and anodic aluminium oxidation of the substrates. L.H.-L. performed the dielectric deposition of ALD Al2O3. ALD TiN deposition, process integration, materials and electrical characterization were carried out by P.B. Data analysis was done by P.B., S.B.L. and G.W.R. All authors discussed the results and contributed to the manuscript.

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Correspondence to Sang Bok Lee or Gary W. Rubloff.

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Banerjee, P., Perez, I., Henn-Lecordier, L. et al. Nanotubular metal–insulator–metal capacitor arrays for energy storage. Nature Nanotech 4, 292–296 (2009).

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