Infrared Plasmonics with Conductive Ternary Nitrides.

Conductive transition metal nitrides are emerging as promising alternative plasmonic materials that are refractory and CMOS-compatible. In this work, we show that ternary transition metal nitrides of the B1 structure and consisting of a combination of group-IVb transition metal, such as Ti or Zr, and group III (Sc, Y, Al) or group II (Mg, Ca) elements can have tunable plasmonic activity in the infrared range in contrast to Ta-based ternary nitrides, which exhibit plasmonic performance in the visible and UV ranges. We consider the intrinsic quality factors of surface plasmon polariton for the ternary nitrides, and we calculate the dispersion of surface plasmon polariton and the field enhancement at the vicinity of nitride/silica interfaces. Based on these calculations, it is shown that among these nitrides the most promising are TixSc1-xN and TixMg1-xN. In particular, TixSc1-xN can have plasmonic activity in the usual telecom bands at 850, 1300, and 1550 nm. Still, these nitrides exhibit substantial electronic losses mostly due to fine crystalline grains that deteriorate the plasmonic field enhancement. This unequivocally calls for improved growth processes that would enable the fabrication of such ternary nitrides of high crystallinity.

Self-assembled plasmonic templates produced by microwave annealing: applications to surface-enhanced Raman scattering.

Perhaps the simplest method for creating metal nanoparticles on a substrate is by driving their self-assembly with the thermal annealing of a thin metal film. By properly tuning the annealing parameters one hopes to discover a recipe that allows the pre-determined design of the NP arrangement. However, thermal treatment is known for detrimental effects and is not really the manufacturer's route of choice when it comes to large-scale applications. An alternative method is the use of microwave annealing, a method that has never been applied for metal processing, due to the high reflectance of microwave radiation at the surface of a metal. However, in this work we challenge the widely used nanostructuring methods by proving the microwave's annealing ability to produce plasmonic templates, out of extremely thin metal films, by simply using a domestic microwave oven apparatus. We show that this process is generic and independent of the deposition method used for the metal and we further quantify the suitability of these plasmonic templates for use in surface-enhanced Raman scattering applications.