Development of the geometry of carbon microcoils from carbon nanofilaments

Carbon coils were deposited on a SiO2 substrate using C2H2/H2 as the source gases and SF6 as the additive gas using a thermal chemical vapor deposition system. The formation of carbon microcoils was investigated during the deposition of the carbon coils. During the early stage of the reaction, carbon nanofilaments were formed on a specific point on the sample. Further deposition reaction increased the density of carbon nanofilaments. At this step, some of the carbon nanofilaments were observed to have a twin formation, namely, two similar shaped carbon nanofilaments attached to each other. The twin carbon nanofilaments transformed into nanosized wave-like carbon coils with increasing length. After further deposition time, the formation of double helix-type geometry of microsized carbon coils was observed, originating from the nanosized wave-like carbon coils. Based on the investigation of the point of transformation from carbon nanocoils into carbon microcoils, the detailed development of the double helix-type carbon microcoils is proposed and discussed.