Optical properties of niobium nitride plasmonic nanoantennas for the near- and mid-infrared spectral range

Abstract

Investigating new materials plays a very important role for advancing the field of nanofabrication and nanoplasmonics. Even though niobium nitride (NbN) is mainly known for its superconducting properties when fabricating superconducting nanowire single-photon detectors, we demonstrate that it is also a material for plasmonic nanoantenna applications. In this work we measure physical properties of thin NbN films, such as permittivity and superconductivity, and demonstrate the feasibility and tuning of the plasmonic nanoantenna resonance throughout the near- and mid-infrared spectral range. Therefore, we fabricate NbN structures, using electron beam lithography in combination with Ar ion-beam etching. Additionally, we determine the refractory properties of the NbN nanoantennas, namely their high temperature stability. We find that they are stable up to 500°C under ambient conditions. These aspects make them attractive for a multitude of plasmonic applications ranging from refractory emitters/absorbers to candidates for plasmonically improved superconducting single-photon detectors.