Tin-doped indium oxide thin film deposited on organic substrate using oxygen ion beam assisted deposition

Tin-doped indium oxide (ITO) thin films were deposited on polyethylene terephthalate (PET) at room temperature by oxygen ion beam assisted evaporator system and the effects of oxygen gas flow rate on the properties of room temperature ITO thin films were investigated. The increase of oxygen gas flow rate to the ion gun at a fixed rf power consistently decreased not only the oxygen ion densities in the ion gun measured by OES but also the oxygen ion flux to the substrate measured by Faraday cup while the atomic oxygen radical measured by OES showed a maximum at 6 sccm of O2 with the increase of oxygen flow rate in our experimental conditions. The increase of oxygen flow rate to the ion gun generally increased the optical transmittance of the deposited ITO up to 6 sccm of O2 and the further increase of oxygen flow rate appears to saturate the optical transmittance. In the case of electrical property, the resistivity showed a minimum at 6 sccm of O2 with the increase of oxygen flow rate. Therefore, the improved ITO properties at 6 sccm of O2 appear to be more related to the incorporation of low-energy oxygen radicals to deposited ITO film rather than the irradiation of high-energy oxygen ions to the substrate. At an optimal deposition condition, ITO thin films deposited on PET substrates showed a resistivity of 6.6×10−4 Ω cm and optical transmittance of above 90%.