Aluminum Nanocrescent Plasmonic Antennas Fabricated by Copper Mask Nanosphere Template Lithography

Aluminum plasmonic nanocrescent antennas were fabricated over large substrate areas by incorporating a sacrificial copper layer in nanosphere template lithography (NTL). The addition of the copper mask eliminates the argon ion milling step in the NTL process that is challenging to implement for aluminum nanostructures because of the robust native oxide layer. The aluminum nanocrescents exhibit polarization-dependent localized surface plasmon responses that can be tuned from the near-infrared into the ultraviolet, a region that is difficult to access with more typically used gold and silver. Finite-difference time-domain simulations predict the observed multimodal plasmonic behavior of these aluminum structures. This simple fabrication process will facilitate the implementation of the aluminum nanocrescent antennas in long and short wavelength surface-enhanced spectroscopies, fluorescence lifetime reduction processes, and photocatalysis.