Nucleation of Carbonaceous Nanoparticles in a Low Pressure Ar/C₂H₂ Plasma with C₂H₄ Impurity

Computer simulations of one-dimensional multi-fluid equations are used to study the effects of C₂H₄ addition on the plasma chemistry and formation of nanoparticles in a capacitively coupled Ar/C₂H₂ plasma. The results indicate that the most important effect is an enhanced production of hydrogen-rich species, especially C₄H₄. Regarding the effect of C₂H₄ inlet on different routes of nanoparticles nucleation, it was found that the nucleation via growth of neutral molecules is significantly suppressed, while the radicals and anions remain almost unaffected. As C₂H₄ participates in many cationic reactions, the concentrations of hydrogen-rich cations are largely enhanced, whereas those of carbon-rich cations are reduced. The numerical results also suggest that the main mechanism behind the production of C₆H₆ is the insertion of the C₂H₃ radical into C₄H₄. The concentrations of the precursors species of C₆H₆ are increased with an increase in the pressure but are reduced with the applied RF voltage.