XPS depth profiles and optical properties of plasma polymer multilayers with embedded metal particles

XPS depth profile of plasma polymer thin films with various embedded metal particles (gold, silver, copper and indium) were used to determine the vertical distribution of the metal particle in the plasma polymer film and to investigate the chemical composition of the films. For plasma polymer gold composite films deposited by simultaneous plasma polymerization of perfluoropropane and gold sputtering, a very homogeneous depth profile of the embedded gold particle was found. Otherwise, multilayer systems consisting of a plasma polymer metal composite film between a bottom and a top plasma polymer film were deposited by plasma polymerization of benzene or styrene and simultaneous or alternating evaporation of gold, silver, copper or indium. The XPS depth profiles demonstrate that the multilayer systems were not destroyed by thermal annealing up to 480 K or by appropriate laser annealing. Except for multilayers with embedded indium particles, oxygen was only adsorbed at the surface and not detected after some monolayers were etched. The optical properties of multilayer systems with embedded gold or silver particles change substantially after thermal annealing. The spectral position of the plasma resonance absorption of the metal particle shifts to higher wave numbers. Based on XPS depth profiles it was demonstrated, that these changes in the optical spectra are only a result of metal particle reshapening and coalescence.