Microstructure and infrared reflectance modulation properties in DC-sputtered tungsten oxide films

Tungsten oxide (WO3) films were deposited on indium tin oxide glass by reactive DC magnetron sputtering of a tungsten target in an oxygen and argon atmosphere at different substrate temperatures. Infrared reflectance modulation properties of the films were investigated in the wavelength range of 2.5-25 mu m. The morphology and structure of the films are strongly dependent on the substrate temperature, and therefore have a great influence on infrared reflectance modulation properties. The charge capacity and diffusion coefficient of H+ ions in WO3 films decrease, and the infrared reflectance modulation and color efficiency first increase and then decrease with increasing the deposition temperature. The values achieve a maximum of 40% and 18.5 cm(2) C-1, respectively, at 9 mu m and 250 A degrees C.