Indium-tin-oxide thin films deposited on polyethylene-terephthalate substrates by substrate-biased RF magnetron sputtering

Indium-tin-oxide (ITO) thin films were deposited on the polyethylene terephthalate (PET) substrates at low temperature (70°C) by RF magnetron sputtering. In order to increase the adatoms mobility at the low growth temperature, the substrate was biased up to -120V in order to increase the kinetic energy of the incoming ions. A series of experiments were carried out to study the influences of the substrate biases on the structural, electrical, and optical properties of the grown films. The results showed that the ITO films grown under the bias exhibited higher crystallinity than those deposited without a bias. The transmittance and electrical properties were also enhanced for the biased films. The lowest resistivity (6.66×10^-4Ω-cm) was achieved under the bias of -40V. The X-ray photoelectron spectroscopy revealed that with the application of substrate bias the Sn⁴⁺/Sn²⁺ ratio was increased, while the portion of the amorphous phase was reduced.