Nano-wrinkling of diamond-like carbon thin films on amorphous polycarbonate and semicrystalline polyethylene terephthalate
Publication from Materials
4th International Congress in advances in applied physics and materials science (APMAS 2014) (Vol. 1653, No. 1, p. 020064) AIP Publishing , 3/2015
The current work explains the influence of semi-crystalline polymers on the topography formation of nano-wrinkled thin diamond-like carbon films. The nano-wrinkling effect is based on relaxation of high intrinsic thin film stresses by a common deformation of a soft substrate surface and a hard thin film. Wrinkles form either in domed or in sinusoidal topography, which is mainly influenced by the polymer substrate, especially the orientation of macromolecular chains. High energetic deposition conditions, like in direct deposition from ion sources, result in high compressive film stresses. While crystalline segments in amorphous polymeric matrix in polyethylene terephthalate favors the formation of sinusoidal wrinkle shape under high energetic conditions, film growth on mostly amorphous polymers (like polycarbonate) is influenced by linear stretching of polymer chains, occurring during polymer manufacturing by foil extrusion. Low energetic deposition conditions, being found in pulsed direct current magnetron sputtering, lead to much lower intrinsic film stress. The lower depth of interaction with the polymer macromolecules for stress relaxation shifts the main influence on wrinkling from the bulk structure to the surface inhomogeneities (like micro-scratches).