Temperature-dependent optical properties of titanium nitride

Abstract

The refractory metal titanium nitride is promising for high-temperature nanophotonic and plasmonic applications, but its optical properties have not been studied at temperatures exceeding 400 C. Here, we perform in-situ high-temperature ellipsometry to quantify the permittivity of TiN films from room temperature to 1258 C. We find that the material becomes more absorptive at higher temperatures but maintains its metallic character throughout visible and near infrared frequencies. X-ray diffraction, atomic force microscopy, and mass spectrometry confirm that TiN retains its bulk crystal quality and that thermal cycling increases the surface roughness, reduces the lattice constant, and reduces the carbon and oxygen contaminant concentrations. The changes in the optical properties of the material are highly reproducible upon repeated heating and cooling, and the room-temperature properties are fully recoverable after cooling. Using the measured hightemperature permittivity, we compute the emissivity, surface plasmon polariton propagation length, and two localized surface plasmon resonance figures of merit as functions of temperature. Our results indicate that titanium nitride is a viable plasmonic material throughout the full temperature range explored.

The Quest for Zero Loss: Unconventional Materials for Plasmonics

“…An intermediate form of TiN, as produced conveniently by reactive magnetron sputtering onto a room temperature surface has a dielectric function that is comparable to that of Cu from the point‐of‐view of sustaining surface plasmons in spheres and other equiaxed shapes. Although the optical properties of TiN become slightly more lossy at elevated temperatures due to increased electron scattering, useful functionality for both LSPR excitation and photothermal heat generation can be maintained to temperatures in excess of 1200 °C . The relatively low cost of TiN, combined with its chemical inertness and refractory nature, suggests that it may find many applications in the plasmonics field.…”

Optimization of a perfect absorber multilayer structure by genetic algorithms

“…This procedure is repeated for all the genes by changing randomly p 1 and p 2 . In this example the fitness of the sons (414, 358) is higher than the ones of their parents (74,63). In general after reproduction a new population of children is generated (see Table 3), which statistically has an average fitness better than the previous one (see Table 2), thanks to the selection rules, and to the general assumption that good parents generate good children.…”

“…In addition TiN has also good mechanical hardness, high corrosion resistance, low frictional constant, thermodynamic stability, relatively good thermal conductivity (≈20 W/m K), low thermal emissivity (< 0.2), very high melting temperature of 2930°C, and a thermal expansion of 9.3 × 10 − 6 K − 1 that that is lower than for gold (14 × 10 − 6 K − 1 ) and silver (18 × 10 − 6 K − 1 ). These properties makes it suitable for applications such as thermal radiation engineering and thermophotovoltaics [62,63]. In our case the TiN layers are alternated with transparent Indium tin oxide layers (ITO) so to design the ITO/ TiN multilayer structure made of M layers as shown in Fig.…”

“…The hemispherical total emissivity should be kept as small as possible (< 0.2) to minimize the radiation losses. The calculation is done by using the literature values for the infrared properties of TiN, ITO, SiO 2 , and silver [61][62][63][64].…”

“…[60], and by taking the optical properties of the materials found in Refs. [47,[61][62][63][64]. No additional supporting information or data are necessary.…”