• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.481-487
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• 2009

To control the diameter size of the carbon nanofilaments (CNFs), SF6 was incorporated in the source gases ($C_2H_2/H_2$) during the initial deposition stage. The source gases and $SF_6$ were manipulated as the cyclic on/off modulation of $C_2H_2/H_2/SF_6$ flow in a thermal chemical vapor deposition system. The characteristics of the CNFs formation on the substrate were investigated according to the different cyclic modulation processes and the substrate temperatures. By $SF_6\;+\;H_2$ flow injection during the cycling etching interval time, the diameter size of CNFs was extremely decreased. The cause for the decrease in the diameter size of the individual CNFs by the cyclic on/off modulation process of $C_2H_2/H_2/SF_6$ flow was discussed in association with the slightly enhanced etching ability by the incorporation of $SF_6$.

• Journal of the Korean Vacuum Society
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• v.21 no.3
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• pp.178-184
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• 2012

Carbon coils could be synthesized on nickel catalyst layer-deposited silicon oxide substrate using $C_2H_2$ and $H_2$ as source gases and $SF_6$ as an additive gas under thermal chemical vapor deposition system. The characteristics (formation density and morphology) of as-grown carbon coils were investigated as functions of additive gas flow rate and the cycling on/off modulation of $C_2H_2/SF_6$ flows. Even in the lowest $SF_6$ flow rate (5 sccm) in this work, the cycling on/off modulation injection of $SF_6$ flow for 2 minutes could give rise to the formation of nanosized carbon coils, whereas the continuous injection of $SF_6$ flow for 5 minutes could not give rise to the carbon coils formation. With increasing $SF_6$ flow rates from 5 to 30 sccm, the cycling on/off modulation injection of $SF_6$ flow confines the geometry for the carbon coils to the nanosized ones. Fluorine's role of $SF_6$ during the reaction was regarded as the main cause for the confinement of carbon coils geometries to the nano-sized ones.

• Journal of the Korean Chemical Society
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• v.48 no.6
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• pp.663-666
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• 2004