Ionic Diffusion In Functional Coatings On Flat Glass & Thin Film Properties

Diffusion reactions in functional coatings on glass are most often accompanied by degradation effects. A well known example is the contamination of functional films by thermally activated sodium diffusion from the glass substrate, which raises the resistivity in case of transparent conductive oxides (TCO). Sodium incorporation in the liquid crystal of LCD's degrades device characteristics. As a consequence, both TCO's and LCD's require either glasses with low sodium outlet or a reliable surface passivation in case of soda lime glass. The examples show that the evaluation of diffusion reactions in thin films on glass depends on the application and that diffusion is controlled by thin film properties.