Figure 4. Effect of nanopillar periodicity on fabrication outcome.

SEM micrographs of the templates, the samples after gold deposition and the samples after dewetting are shown for nanopillar periodicities (A) p = 30 nm, (B) p = 50 nm, and (C) p = 150 nm. Phase field simulation results were also shown for all three periodicities. At p = 30 nm, after gold deposition, the neighboring gold caps were joined due to the small spacing. Thermal treatment did not yield nanoaperture array at this periodicity. At p = 50 nm and larger, the gold caps dewet off nanopillars, resulting in clear nanoapertures. We note that the positions of the gold caps after gold deposition appeared to deviate from the regularity of the nanopillars arrays. These positional jitters appeared to be partially removed with thermal treatment, resulting in nanoapertures with more regular periodicities.