2D and 2.5D plasmonic metastructures for surface-enhanced infrared absorption applications: fabrication and properties

Abstract

Metamaterials possesses novel electromagnetic properties and have great potential for applications. Different type of nanosized plasmonic antennas considered to be effective functional materials in infrared spectrum. Still, strict requirements on dimensions and periodicity of nanostructures limits their practical implementation. Here, we have fabricated 2D and 2.5D different topology arrays of nanosized plasmonic antennas using e-beam and direct laser writing (DLW) lithography techniques. Appling the DLW method we created periodic polymer structures that act as a template for creating plasmonic nanoantennas with metallization and lift-off techniques. Improvement of the morphological parameters of such structures is possible due to STED-DLW (STimulated Emission Depletion assisted Direct Laser Writing) compatible photoresist. With e-beam lithography and lift-off techniques we obtained arrays of gold plasmonic nanoantennas. Using standard Fourier-transform microscopy we measure the spectral properties of fabricated nanostructures. We show that observed position, intensity and Q-factor of the collective surface plasmon resonance are directly conditioned by fabrication process. Thus, the studied structures can be applied as substrates for surface-enhanced infrared absorption (SEIRA). SEIRA antenna arrays in its turn possess considerable potential in real-world applications such as chemical and biological vibrational sensing.