Controlled Geometry Formation of the Carbon Coils by the Substrate Pretreatment

Carbon coils could be synthesized using C2H2/H2 as source gases and SF6 as an incorporated additive gas under thermal chemical vapor deposition system. Prior to the carbon coils deposition reaction, the supporting substrates were pretreated using various methods. Among the methods, the thermal etching pretreatment of Ni-SiO2 substrate with SF6 leads to the exclusive formation of the nanosized carbon coils. The diamond powders pretreatment of Si substrate gives rise to the dominant formation of the microsized carbon coils after 10 minutes reaction time. The geometry selectivity for the carbon coils in a specific pretreatment method was discussed in association with the peeled-off Ni layers by the thermal etching pretreatment with SF6 and the remained carbon particles on Si substrate by the diamond powders pretreatment.