RF sputtering deposition of Ag/ITO coatings at room temperature

Indium tin oxide (ITO) thin films were deposited on unheated polyester and glass substrates by RF sputtering from ceramic ITO and metal targets. ITO films deposited on polyester substrates showed resistivities of 6×10−6 Ω·m and square resistances of 16 Ω/□ as well as optical transmittances of 70%. Highest conductivities were achieved using low Ar pressures of 0.4 Pa (without oxygen), and high power densities of 2×104 W m−2. Glass and polyester substrates exhibited different growth rates and samples deposited onto glass substrates showed better adhesion of the film. The addition of silver layers in the ITO films resulted in lowering their electrical resistivity with a slight reduction of their optical transmittance. These films have been produced using a simple sputtering system at room temperature and can be deposited homogeneously on large area elastic substrates with square resistances (R□) on the order of 20 Ω/□. Electrical and optical properties of ITO samples have been studied by electrical, Hall mobility and optical transmittance (UV–visible range) measurements. The results are discussed in terms of their application as transparent electrodes in large area electrochromic devices.