Low-temperature synthesis of single-walled carbon nanotubes by alcohol gas source growth in high vacuum

Carbon nanotube (CNT) growth was carried out on SiO2/Si substrates with a Co catalyst using an alcohol gas source method in an ultra-high vacuum chamber. The resulting CNTs were characterized by scanning electron microscopy (SEM), Raman spectroscopy and transmission electron microscopy (TEM). Reducing the ethanol pressure decreased the optimum growth temperature for maximum yield, enabling single-walled carbon nanotube (SWNT) growth at 400 degrees C. By employing an Al2Ox buffer layer, SWNT yield increased several times, even at 400 degrees C. Under TEM observation, the Co particle size on the Al2Ox layers did not show a significant dependence on the growth temperature between 400 and 700 degrees C. Raman and TEM results confirmed activation of Co particles with larger diameter (>1 nm) by the Al2Ox buffer layer.