Single-Walled Carbon Nanotube Growth in High Vacuum Using Pt Catalyst in Alcohol Gas Source Method

Growth of single-walled carbon nanotubes (SWNTs) was carried out on SiO2/Si substrates at 700 degrees C with Pt catalysts using an alcohol gas source method in a high vacuum. Scanning electron microscopy observations and Raman spectroscopy measurements showed the optimal ethanol pressure to be 1 x 10(-4) Pa, which was much smaller than that used in the SWNT growth with a Co catalyst. Raman spectra measured with various excitation wavelengths showed that the G/Si ratios of the SWNTs grown with the Pt catalyst at 1 x 10(-4) Pa was fairly larger than those grown with the Co catalyst at 1 x 10(-1) Pa, indicating that the SWNT yield of the former was higher than that of the latter, in spite of the lower ethanol pressure. These results indicate that by using the Pt catalyst, the optimal ethanol pressure was considerably reduced, compared to the conventional Co catalyst. The usefulness of Pt catalyst for SWNT growth under low pressure was demonstrated for the first time.