Thickness dependence of electrical properties of ITO film deposited on a plastic substrate by RF magnetron sputtering

Indium tin oxide (ITO) films with various thicknesses in range of 40–280 nm were prepared onto a plastic substrate (PMMA). Deposition was carried out with RF magnetron sputtering method and the substrate temperature was held at 70 8C, in lack of the thermal damage to the polymer substrate. Changes in microstructure and electrical properties of ITO films according to their thicknesses were investigated. It was found that amorphous layer with thickness of 80 nm was formed at the interface on the polymer substrate and polycrystalline ITO could be obtained above the thickness. Conductivity of ITO films was found to be strongly dependent on the crystallinity. Consequently, it is suggested that crystallinity of the deposited films should be enhanced at the initial stage of deposition and the thickness of amorphous region be reduced in order to prepare high quality ITO thin films on polymer substrates