Control of optical properties of TiN_xO_y films and application for high performance solar selective absorbing coatings

TiN_xO_y films with controllable optical properties have been fabricated by reactive mid-frequency magnetron sputtering from titanium nitride target. The optical and electrical properties were studied as a function of the reactive gas flow and were correlated with the film stoichiometry. The results showed that the behavior of TiN_xO_y films can be adjusted from metallic to dielectric by increasing oxygen content, which is of great significance to their extensive applications. Owing to the accurate control of optical properties, a TiN_xO_y based solar selective absorbing coating has been designed and prepared with the aid of TiO₂/Si₃N₄/SiO₂ antireflection layers. Its solar absorbance is as high as 97.5% and thermal emissivity is 4.3% with total thickness of 230 nm. The solar absorbance can maintain above 90% for a broad incident angle range from 0° to 65°.