Plasma polymerization of allyltrimethylsilane with single-filament dielectric-barrier discharges—Evidence of cationic surface processes

Atmospheric-pressure plasma-enhanced film deposition with single-filament dielectric-barrier discharges (DBDs) in argon was investigated using allyltrimethylsilane (ATMS) as a precursor. Nonionic deposition in the discharge zone is largely precluded by a rapid cross-flow of the source gas, containing between 50 and 2000 ppm of ATMS. The performed experimental studies show a surprisingly large deposited film mass per transferred elementary charge between 220 and 540 amu. Film growth experiments, mass-spectrometric studies, and kinetic considerations led to the conclusion that the deposition process is a cationic surface polymerization, initiated by ions produced in the DBD by energy transfer from long-lived excited Ar species and propagated by addition of ATMS monomer molecules.