Three-dimensional architecture of inorganic nanoarrays electrodeposited through a surface-layer protein mask

Transmission electron microscopy was used to analyze the three-dimensional (3D) architecture of cuprous oxide electrochemically deposited through the pores of the hexagonally packed intermediate surface-layer protein from Deinococcus radiodurans SARK. Imaging at multiple tilt angles and averaging from five different samples allowed approximately 3 nm computed 3D reconstructions of the inorganic deposit and protein template. We show that the electrodeposition process used here was able to fully access the pore structure that penetrates the protein layer, allowing the fabrication of a polycrystalline nanoarray with 18 nm periodicity and lateral interconnectivity among the pores with 3-fold symmetry. At the resolution of the reconstruction, the 6-fold symmetry pores also appear filled but are not connected laterally to the rest of the deposit. These results show that electrochemical deposition can produce interconnected 3D structures at dimensions an order of magnitude smaller than the most advanced integrated circuits (IC), boding well for continued down-scaling of electrodeposition to meet the needs for future generations of IC device interconnects.