Simulation and Fabrication of Nanoscale Spirals Based on Dual-Scale Self-Assemblies.

Archimedean spirals in nanometer scale have shown remarkable plasmonic responses derived from their linear and rotational asymmetry. Despite the unique optical properties of nanoscale spirals, their applications have been limited due to the difficulty in fabricating large-scale arrays with uniform and systematic control of the morphology. Here, we report simulation results of spiral morphologies, which are used to design a scalable fabrication process for nanoscale spirals and predict their plasmonic responses. First, self-consistent field theory (SCFT) simulations were performed to design optimal templates to guide self-assembly into spiral morphologies. Using the SCFT results, we developed a scalable fabrication process, which is based on the micron-scale assembly of microspheres combined with glancing angle deposition and nanoscale assembly of block copolymers, to induce the formation of uniform nanospirals with diverse size, handedness, orientation, and winding number. Finally, finite-difference time-domain simulation results show linear dichroism and electric field intensity enhancement effects of these nanospirals, which are highly dependent on the winding number of the spirals, indicating the importance of precise control of the structural parameters.