PULSED-LASER DEPOSITION OF CRYSTALLINE TEFLON (PTFE) FILMS

Thin films of crystalline polytetrafluoroethylene (PTFE) were prepared by pulsed-laser deposition using 248 nm UV-excimer-laser radiation. P ressed powder pellets and bulk PTFE have been employed as target mater ial. The films were analyzed by means of optical polarization microsco py, stylus profilometry, capacity measurements, XRD, and IR spectrosco py. The effect of substrate temperature T-s on the morphology and crys tallinity of the films was studied. Films deposited from pressed powde r targets at sufficiently high T-s consist mainly of spherulite-like m icrocrystallites. These films are continuous, pinhole-free, well adher ent to the substrate, and have a composition which is similar to that of the target material. It is suggested that film formation is based o n laser-assisted material transfer with subsequent melting and crystal lization. They are superior to films deposited from PTFE bulk targets, cut from a solid rod, with respect to film morphology, deposition rat e, film cohesion, and optical and electrical properties. (C) 1998 Else vier Science B.V.