Investigation of SF6 injection during cyclic C2H2/SF6 flow for the formation of geometrically controlled carbon coils.

Carbon coils could be synthesized using C2H2/H2 as source gases along with SF6 as an incorporated additive gas using a thermal chemical vapor deposition (CVD) system. To obtain geometrically controlled carbon coils, a cyclic process, namely the turning on and off of C2H2 or SF6 flow during the initial reaction stage, was carried out. According to the different reaction processes, different interruption/injection times of C2H2 or SF6 flow and different injection sequences of the gas flow were investigated while maintaining the identical overall injection time of C2H2 and/or SF6 flow.

Dominant formation of the microsized carbon coils by a short time SF6 flow incorporation during the initial deposition stage.

By SF6 gas incorporation for relatively short time during the initial deposition stage, carbon coils could be formed on nickel catalyst layer-deposited silicon oxide substrate using C2H2 and H2 as source gases under thermal chemical vapor deposition system. The characteristics (formation density and morphology) of as-grown carbon coils were investigated as a function of SF6 flow injection time. 5-min SF6 flow injection time is appropriate to produce the dominant microsized geometry for carbon coils without the appearance of the nanosized carbon coils.

Developing aspect of carbon coils formation during the beginning stage of the process.

Carbon coils could be synthesized using C2H2/H2 as source gases and SF6 as an incorporated additive gas under thermal chemical vapor deposition system. The surface morphologies of samples were investigated step by step during the beginning stage of the process. After finishing the substrate temperature set to 750 degrees C, the formation of circular-type nickel clusters were observed in places.

Effect of gas phase composition cycling on/off modulation numbers of C2H2/SF6 flows on the formation of geometrically controlled carbon coils.

Carbon coils can be synthesized using C2H2/H2 as source gases and SF6 as an incorporated additive gas under a thermal chemical vapor deposition system. In this study, nickel catalyst layer deposition and then hydrogen plasma pretreatment were performed prior to the carbon coils deposition reaction. To obtain geometrically controlled carbon coils, source gases and SF6 were manipulated as the cycling on/off modulation numbers of C2H2/SF6 flows.

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.