Controlled syntheses of Ag-polytetrafluoroethylene nanocomposite thin films by co-sputtering from two magnetron sources

Co-sputtering from two independent magnetron sources was used to prepare polymer-metal nanocomposite films. Both gradient films with increasing metal fraction and homogeneous composite films were produced from polytetrafluoroethylene (PTFE) and silver targets using a rotatable sample holder. The structure of the pure sputtered polymer as well as the composite structure was studied. Electrical properties of the composite material near the percolation threshold show the expected, sharp change in the resistivity from 10(7) Omega cm at small silver content to 10(-3) Omega cm after percolation. The optical absorption in the visible region due to surface plasmon resonances also has a strong dependence on the metal content, showing a red shift of the absorption peak from 405 nm to more than 500 nm at higher silver content.