Near-Zero Negative Real Permittivity in Far Ultraviolet: Extending Plasmonics and Photonics with B1-MoN_x

Abstract

CMOS-compatible, refractory conductors are emerging as the materials that will advance novel concepts into real, practical plasmonic technologies. From the available pallet of materials, those with negative real permittivity at very short wavelengths are extremely rare; importantly they are vulnerable to oxidationupon exposure to far UV radiationand nonrefractory. Epitaxial, substoichiometric, cubic MoN (B1-MoNx) films exhibit resistivity as low as 250 cm and negative real permittivity for experimental wavelengths as short as 155 nm, accompanied with unparalleled chemical and thermal stability, are reported herein. Finite-difference time domain calculations suggest that B1-MoNx operates as an active plasmonic element deeper in the UV (100-200 nm) than any other known material, apart from Al, while being by far more stable and abundant than any other UV plasmonic conductor. Unexpectedly, the unique optical performance of B1-MoNx is promoted by nitrogen vacancies, thus changing the common perception on the role of defects in plasmonic materials.

Tunable Infrared Plasmonic Properties of Epitaxial Ti1–xMgxN(001) Layers

“…1,2 They affect polarization and screening within a material and amplify external fields at interfaces. 3 Of particular interest are surface plasmon polaritons (SPP) and localized surface plasmon resonances (LSPR) which extend along planar boundaries for the former and at the surface of metallic nanoparticles for the latter 4 and are studied because of their diverse potential applications in micro-electronics, 5 biosensing, 6 photodetection, 7 metamaterials, 8 solar energy harvesting, 9 telecommunications, 10 and optical information storage. 11 An ideal plasmonic material exhibits a real permittivity ε 1 with a steep transition from negative to positive values at the desired plasmonic response frequency and an imaginary permittivity ε 2 that is small over the entire spectrum to minimize optical losses.…”

Structure, stress, and mechanical properties of Mo-Al-N thin films deposited by dc reactive magnetron cosputtering: Role of point defects

“…[20][21][22][23][24][25][26] The optical properties of an epitaxial cubic MoN x film (x = 0.69) are also very appealing for ultraviolet technologies, as this compound exhibits negative and near-zero real permittivity combined with room temperature resistivity as low as 250 μΩ cm. 27 The presence of nitrogen vacancies in MoN x is believed to impart its unique optical performance. MoN is also a suitable coating candidate to enhance the tribological properties over common hard coatings due to its low friction coefficient and reduced wear rate at temperatures lower than 500°C.…”

Spectrally Tailored Light‐Matter Interaction in Lithography‐Free Functional Nanomaterials

“…It is shown that some of these materials may present a negative ε 1 in the visible, thanks (at least in part) to strong interband transitions: Pt, Zn, Cd, Ru. The fact that such properties are not limited to p block materials is supported by their recent observation for the CuFeS 2 chalcopyrite (where intermediate bands play a key role in establishing the plasmonic properties) and very recently for the substoichiometric oxide MoN x . This latter work brings the very interesting idea that electronic bands generated upon introducing defects in the crystal lattice can enable interband transitions strong enough to induce a negative ε 1 in the visible.…”

“…The fact that such properties are not limited to p block materials is supported by their recent observation for the CuFeS 2 chalcopyrite (where intermediate bands play a key role in establishing the plasmonic properties) and very recently for the substoichiometric oxide MoN x . This latter work brings the very interesting idea that electronic bands generated upon introducing defects in the crystal lattice can enable interband transitions strong enough to induce a negative ε 1 in the visible. Negative ε 1 values were reported in the visible at the short wavelength side of strong absorption bands in TiO x N y compounds; however, this was attributed to effective medium effects resulting from the granular structure of the material (TiN nanoparticles in a TiO x N y matrix) .…”