Aluminum Nanowire Arrays via Soft Nanoimprint Lithography

We have previously reported a method to fabricate freestanding, vertically-oriented, and lithographically-ordered Al nanowire arrays via directed assembly, and demonstrated their utility as a plasmonic waveguide\footnote{N. T. Nesbitt, J. M. Merlo, A. H. Rose, Y. M. Calm, K. Kempa, M. J. Burns, \& M. J. Naughton, \textit{Nano Lett.} \textbf{15}, 7294-7299 (2015)}. However, the process, a variation on the preparation of anodized aluminum oxide (AAO), involved imprinting Al with a hard stamp, which wore down the stamp and had a low yield of Al NWs. Here we show a new nanoimprint lithography (NIL) technique that uses a soft stamp to pattern a mask on the Al; it provides a greater yield of Al NWs and is less destructive to the stamp, providing a path to applications that require NW arrays over macroscopic areas.