MNM-4A-4 大気圧プラズマによる単層カーボンナノチューブ成長促進(セッション 4A ナノ材料と熱工学)

概要

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Carbon nanotube (CNT) growth mechanism in plasma enhanced chemical vapor deposition (PECVD) is presented. Plasma-induced decomposition of CH_4, as an initial feed stock, was investigated by quadrupole mass spectrometry and gas chromatography analysis, showing that 30% of initial CH_4 was converted to C_2H_6, C_2H_4 and a trace amount of C_2H_2. Higher hydrocarbons such as C_3 and C_4 components were not detected. A trace amount of C_2H_2 (ca. 100 ppm) enables single-walled CNTs in the thermal CVD regime only when CH_4 is supplied simultaneously : C_2H_6 and C_2H_4 did not grow CNTs in the same way. CH_4 works as an etchant and eliminates amorphous carbon efficiently ; however, CH_4 does not contribute as carbon source because CNT growth rate was not accelerated in the C_2H_2/CH_4 system. H_2 is necessary to grow SWCNTs in the PECVD regime because H_2 suppresses C_2H_2 formation due to plasma-induced decomposition of CH_4: Hydrogen seems not to contribute amorphous carbon elimination even if H2/C_2H_2 ratio is as high as 400.
2010-10-12