Characterization of oxide gas barrier films

摘要

The aim of this study was to investigate the microstructure and the gas barrier performance of AlO_x layers of varying thickness (23 to 34nm), deposited by mangetron sputtering on polyethylene terephthalate substrates. The gas barrier properties of the films were found to be good, as expected for the thickness range selected. A variety of techniques were used to mcrostructurally characterise the oxide coatings. Atomic force microscopy showed that the barrier layers had grown densely with an average grain size of 40nm. also, it was shown that the coating surface were smotth, a feature that is beieved to facilitiate good water vapour barrier properties. High resolution electron microscopy showed that the barrier layers are amorphous and feature a small number of micro-pores up to 1 nm diameter size. A combination of the compactness, low surface roungness of the narrier coating together with few macro-scale defects are thought to be responsible for the good barrier properties shown by these films.