Large-Aperture and Grain-Boundary Engineering through Template-Assisted Metal Dewetting for Resonances in the Short Wave Infrared

We extend the fabrication method of template-assisted metal dewetting (TeAMeD) to create near-infrared resonant nanostructures in an Au film without the need for etching or lift-off. TeAMeD has previously been used to generate high aspect-ratio sub-10 nm apertures, but struggles to generate larger apertures (>100 nm). In this work, we introduce a method to create larger apertures using templates consisting of fin-like patterns with radial symmetry. We also report evidence of grain boundary engineering, through the template pinning effect. Our three-dimensional phase field model of TeAMeD predicts both the grain-boundary pinning and aperture opening effects that agree well with experiments. Combined with simulation design, TeAMeD can be established as a grain engineering platform, allowing grain shape and boundary position to be controlled. Variations of template motif produce larger grains and numerous possible outcomes, including suspended Au nanodisks and triangular apertures.