Formation of the geometrically controlled carbon coils by manipulating the additive gas (SF6) flow rate

Carbon coils could be synthesized using C2H2/H2 as source gases and SF6 as an incorporated additive gas under the thermal chemical vapor deposition system. The nickel catalyst layer deposition and then hydrogen plasma pretreatment were performed prior to the carbon coils deposition reaction. The flow rate and the injection time of SF6 varied according to the different reaction processes. Geometries of carbon coils developed from embryos to nanosized coils with increasing SF, flow rate from 5 to 35 sccm under the short SF6 flow injection time (5 minutes) condition. The gradual development of carbon coils geometries from nanosized to microsized types could be observed with increasing SF6 flow rate under the full time (90 minutes) SF6 flow injection condition. The flow rate of SF6 for the coil-type geometry formation should be more than or at least equal to the flow rate of carbon source gas (C2H2). A longer injection time of SF6 flow would increase the size of coils diameters from nanometer to micrometer.