Optical Properties of Reactive Sputtered Tungsten Oxide Thin Films

Tungsten oxide thin films play a major role in electrochromism and it¿s the most investigated electrochromic material. Studies have shown that structural, electrical and optical properties of tungsten oxide thin films depend on deposition conditions and preparation techniques. In this work, the optical properties of tungsten oxide thin films prepared in reactive dc magnetron sputtering of tungsten target with argon in oxygen atmosphere have been studied. The optical properties of films prepared at different sputtering power from 300 watts to 400 watts and sputtering pressure in the range (0.65 ¿ 0.90) Pa were investigated through the transmittance spectra recorded by optical spectroscopy measurements in the wavelength range 300-800 nm. The experimental curves of transmittance are reproduced by simulations to determine the band gap energy, refractive index, extinction coefficient, and film thickness of tungsten oxide films.