Large-area arrays of gold nanotructures from azopolymer templates (Conference Presentation)

Subwavelength-sized, periodically arranged holes in an opaque metal film have gained much attention since 1998, when Ebbesen et al. first reported the phenomenon of enhanced transmission of light through such a hole-array structure. Certain wavelengths show distinctly higher transmission than what would be expected based simply on the number of holes and the transmission of a single subwavelength hole, a phenomenon commonly attributed to different plasmonic modes in nanohole arrays. Traditionally, nanoscale holes and slits in metal films have been fabricated via electron-beam lithography or focused ion beam milling. Typically, finite hole arrays up to 50 μm in size with high control over hole size, shape, periodicity and resolution can be created with these methods. However, EBL and FIB become very costly and time-consuming to make larger-sized hole arrays and are not suitable for low-cost mass production. Herein, we exploit surface patterns on azopolymer films for making highly ordered and uniform arrays of nanoholes and nanoislands in thin gold films. The nanostructures can be created by employing azopolymer surface patterns as a template for metal deposition, after which the metal surface is subjected to large-area ion milling. Azopolymer-based surface patterning provides an easy way to vary the size and periodicity of the structures, which are manufactured homogeneously over large areas. The largest possible size of the structures depends merely on the size of the optical inscription beam and the used ion milling apparatus.