Dielectric properties and resistance to fatigue failure of different barrier layers prepared on flexible stainless-steel foils by ion-beam assisted deposition

A stainless-steel foil is an attractive candidate for the substrate of flexible display devices and integrated solar modules. For electrical insulation and ion diffusion reduction, a barrier layer should be coated on the stainless-steel foil surface. In this study, different barrier layers such as SiOx, TaOx, TiOx and TaOx/SiOx were prepared on the flexible stainless-steel foils (SUS 304) by ion-beam assisted deposition. The dielectric properties of the barrier layers, including resistance, reactance, leakage current density, breakdown field strength and performance index, were investigated. The resistance to fatigue failure of the barrier layers was evaluated by insulating tests after the specimen foils were flattened. The results show that the dielectric properties and the resistance to fatigue failure of the TaOx/SiOx composite barrier layer are better than those of the SiOx or the TaOx barrier layer. The best dielectric properties and resistance to fatigue failure are achieved with the 4-mu m thick TaOx/SiOx composite barrier layer.