Transport and condensation of soft a-C:H film thermal decomposition products

Thermal destruction of soft a-C:H films obtained on a wall of a cylindrical quartz reactor during CH4 dissociation in inductively coupled RF discharge (T=300 K) has been investigated. The films were sublimated in argon or methane (pressure of 10–100 Pa). A sublimation rate of a-C:H films increased with temperature rise from 450 to 700 K or an increase in a gas-carrier (Ar or CH4) flow rate in the range of 0.003–0.1 Pa m3/s. Sublimation products (volatile hydrocarbon molecules) were transported along the tube towards lower temperature regions. Fractional temperature-spatial condensation of hydrocarbons occurred during the transport of sublimation products. A high amount (30–100%) of the sublimated hydrocarbons was involved in condensation depending on the transport conditions (flow rate, sublimation and condensation temperatures).