Zak Blumer1 Martin Kordesch1

1, Ohio University, Athens, Ohio, United States

Metal nanostructures are capable of plasmonic selective absorption in specific regimes of the electromagnetic spectrum, consequently leading to a higher ratio of absorption to re-radiation than that of a blackbody absorber. Selective absorbers are candidates for solar thermal energy generation, especially those materials with a large imaginary part of their dielectric function, such as gold. Titanium nitride (TiN) is a ceramic metal that absorbs in the visible and near-infrared range, with a large imaginary part of its dielectric constant—similar to gold and an ideal characteristic for absorption. It is also significantly less expensive, more chemically stable, and more thermally resistant than both gold and silver. TiN thin film shells (100-300 nm) have been grown on glass microbeads (3-10 μm diameter) on a heated boro-aluminosilicate glass substrate (300-600 K) by radio frequency (RF) sputtering physical vapor deposition (PVD) at 7 mTorr (ρAr = 6, ρN = 0.5 mTorr) for 3-24 hours. Raman spectra for the films show consistent peaks at 210, 310, and 550 rel. cm-1. X-ray diffraction (XRD) spectra confirmed crystallization of TiN at higher temperatures, with two peaks representing the (200) and (220) orientations. An analysis of the optical properties of the TiN nanoshells, obtained by spectroscopic ellipsometry (SE), will be presented.