Progress Report FY 1987: Development of TiN Low-E Coatings

Titanium nitride (TiN) shows promise as a low-emittance coating for windows because it possesses both the optical properties of a metal and the hardness and inertness of a ceramic. Titanium dioxide (TiO₂) is a convenient choice for a matching layer to enhance the solar transparency. TiN and TiO₂ films have been deposited on glass by reactive dc magnetron sputtering, which is a standard technique used for production of window coatings. The composition of these films was determined by X-ray photoelectron spectroscopy (XPS). Incorporation of N and O appears to follow the Langmuir adsorption isotherm at low partial pressures. Structure was determined by x-ray diffraction, using both Seemann-Bohlin and conventional Bragg-type geometries. Nonequilibrium phase diagrams have been prepared from this information for various deposition conditions. The properties of these films depend strongly on the sputtering conditions, especially gas pressures, substrate temperature, and bias voltage. Emittance values have been achieved that are much lower than those of TiN films produced commercially. Multilayer coatings have been deposited with greatly improved spectral selectivity.