Pulsed plasma polymerization of tetramethyltin: Nanoscale compositional control of film chemistry

The pulsed plasma polymerization of tetramethyltin monomer was studied as a function of the radio frequency (rf) duty cycle employed, all other plasma variables being held constant. Progressive increases in the relative tin content of the plasma deposited films were observed with systematic decreases in the rf duty cycles employed during film formation. The variations in tin content of these films were documented by XPS, FT-IR, TEM, AFM, and electrochemical analyses. A particularly interesting aspect of this work is the microstructure of the films which reveals spherical tin particles of essentially uniform diameters (20-30 nm) independent of the duty cycle during deposition. The increasing metal content in these films with decreasing duty cycle corresponds' to increased aggregation of these nanosized particles into progressively larger sized clusters. The results obtained are supportive of the use of the variable duty cycle pulsed plasma deposition technique as a new route to improved nanoscale film chemistry control in the synthesis of organometallic composite films.