In situ observation of nanostructural changes of embedded silver and indium nanoparticles

Thin plasma polymer films with embedded silver or indium nanoparticles were deposited by simultaneous plasma polymerization and metal evaporation as multilayer systems. The multilayer consists of a first plasma polymer layer and the metal particles are embedded completely. At these plasma polymer films with embedded metal nanoparticles, the nanostructure changes during thermal annealing and artificially structured materials can be realized with laser irradiation and focused electron beam exposure. The topic of this paper is to identify the physical processes which cause nanostructural changes in polymer films with embedded metal particles. Only in situ investigations can give information about the diffusion processes which are responsible for the nanostructural changes. During annealing in situ in the transmission electron microscope, large nearly spherical silver particles were formed. These recrystallization is a result of atomic diffusion along the particle surface and along the gra in boundaries. Furthermore, during in situ study of coalescence of neighboring silver particles, orientation changes of the atomic planes were observed. At a multilayer system with well-seperated silver particles, very small particles d <= 10 nm disappear during annealing, but no significant changes of the size and shape of large 20nm <= d <=60 nm particles were found. These was interpreted as a result of atomic diffusion of silver through the polymer matrix. At plasma polymer films with embedded indium particles, the formation of very small indium oxide particles was observed and no reshaping or coalescence was found