Effect of the on/off Cycling Modulation Time Ratio of C₂H₂/SF₆ Flows on the Formation of Geometrically Controlled Carbon Coils

Figure 1

Different reaction processes: the steady injection process without incorporating the cycling modulation process for C₂H₂ + H₂ flows (process I, sample A) and C₂H₂ + H₂ + SF₆ flows (process VI, sample F), the cycling on/off modulation of C₂H₂/SF₆ flows having the higher growing/etching time ratio (180/30 s) for two cycles (process II, sample B) and for sixteen cycles (process IV, sample D), the cycling on/off modulation of C₂H₂/SF₆ flows having the lower growing/etching time ratio (30/180 s) for two cycles (process III, sample C) and for sixteen cycles (process V, sample E).