Enhanced barrier performance of SiO_x-modified polymer substrates: Some morphological considerations

The morphological features of thin SiO_x films deposited on polystyrene and polycarbonate substrates were studied using atomic force microscopy and transmission electron microscopy. Preliminary evidence for additional morphology/permeability relationships was provided. The permeance of SiO_x-coated polymers depended strongly on both the film roughness and thickness, decreasing with a reduction in roughness or an increase in thickness. To a lesser extent, the barrier performance also depended on the deposition power level, suggesting that an optimal power level may exist.