Optical and electrical properties of TiO₂/Au/TiO₂ multilayer coatings in large area deposition at room temperature

TiO₂/Au/TiO₂ multilayer thin films were deposited at polymer substrate at room temperature using dc (direct current) magnetron sputtering method. By varying the thickness of each layer, the optical and electrical properties of the TiO₂/Au/TiO₂ multilayer films can be tailored to suit different applications. The thickness and optical properties of the Au layer and the quality of the Au-dielectric interfaces are critical for the electrical and optical performance of the Au-dielectric multilayer thin films. At the thickness of 8 nm, the Au layer forms a continuous structure having the lowest resistivity and it must be thin for high transmittance. The multilayer stack can be optimized to have a sheet resistance of 6 Ω/sq. at a transmittance over 80% at 680 nm in wavelength. The peak transmittance shifts towards the long wavelength region when the thickness of the two TiO₂ (upper and lower) layers increases. When the film thickness of the two TiO₂ film is 45 nm, a high transmittance value is obtained for the entire visible light wavelength region.