Improved infrared emissivity of diamond-like carbon sandwich structure with titanium nitride metallic interlayer

Abstract

In this study, a novel titanium nitride (TiNx) based low-emissivity (low-e) coating of which dielectric layer is a diamond-like carbon (DLC) film deposited as a three-layer stack on a glass substrate using direct current (DC) magnetron sputtering technique. For TiNx thin films, the sputtering power was changed between 25 W and 135 W. Influences of the sputtering power on phase, microstructure, bonding properties, resistivity, optical properties and infrared emissivity of the films were characterized by UV–VIS–NIR spectrophotometery, XRD, SEM, AFM, XPS, four-point probe and FTIR, respectively. It was observed that the metallic character, crystallinity, stoichiometry, reflectance in visible region as well as infrared emissivity of TiNx films were significantly affected by sputtering power. TiNx films deposited at higher plasma power had a more significant negative real part of dielectric function, exhibited better crystallinity, were more stoichiometric, had a lower resistivity and a lower infrared emissivity. The emissivity of the films decreased from 0.52 to 0.17 with increased sputtering power from 25 W to 135 W. The designed low-e coating with a structure of DLC/TiNx/DLC in the current study had an emissivity of 0.49. This coating had an optical transmission of approximately 45% over the visible spectra. These results suggest that the DLC/TiNx/DLC structure could be a good candidate for being used in low-e applications on glasses.