Tunable Silver Nanocap Superlattice Arrays for Surface-Enhanced Raman Scattering

We report on a convenient nanotechnique to fabricate large-area silver nanocap superlattice arrays templated by the base of porous anodic alumina membranes as robust and cost-efficient surface-enhanced Raman scattering substrate. The topography can be tuned to optimize the enhancement factor by adjusting anode voltages or the time of silver magnetron sputtering. Our technique is especially promising considering their easy fabrication and evenly distributed plasmonic fields to cm-dimensions featuring high average enhancement factor, thereby boding well for application in the sensing device.