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Individually addressable epitaxial ferroelectric nanocapacitor arrays with near Tb inch−2 density


Ferroelectric materials have emerged in recent years as an alternative to magnetic and dielectric materials for nonvolatile data-storage applications1,2,3,4,5. Lithography is widely used to reduce the size of data-storage elements in ultrahigh-density memory devices6,7,8,9. However, ferroelectric materials tend to be oxides with complex structures that are easily damaged by existing lithographic techniques, so an alternative approach is needed to fabricate ultrahigh-density ferroelectric memories. Here we report a high-temperature deposition process that can fabricate arrays of individually addressable metal/ferroelectric/metal nanocapacitors with a density of 176 Gb inch−2. The use of an ultrathin anodic alumina membrane as a lift-off mask makes it possible to deposit the memory elements at temperatures as high as 650 °C, which results in excellent ferroelectric properties.

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Figure 1: Fabrication of the nanocapacitors.
Figure 2: MFM nanocapacitor.
Figure 3: Ferroelectric properties.
Figure 4: High-resolution X-ray diffraction patterns of epitaxial PZT nanoislands grown on Pt/MgO(100).


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H. Han is grateful for the award of a fellowship of the German Academic Exchange Service (DAAD) and for support by DFG and KRF. Financial support from the Volkswagen Foundation (Project I/80897) and partly from the Brain Korea 21 Program is also acknowledged. We are thankful to S. Swatek and N. Schammelt for TEM sample preparation. We also thank R. Hillebrand for discussions on statistical analyses for the size distribution and 2D ordering of ferroelectric nanocapacitors.

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Correspondence to Woo Lee.

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Lee, W., Han, H., Lotnyk, A. et al. Individually addressable epitaxial ferroelectric nanocapacitor arrays with near Tb inch−2 density. Nature Nanotech 3, 402–407 (2008).

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