Single-walled carbon nanotube synthesis on SiO2/Si substrates at very low pressures by the alcohol gas source method using a Pt catalyst

Abstract

A platinum catalyst was used for single-walled carbon nanotube (SWCNT) growth on SiO2/Si substrates using an alcohol gas source method, a type of cold-wall chemical vapor deposition. Compared to Co, a conventional transition metal catalyst, the optimal ethanol pressure was considerably reduced in the growth at 700°C, and SWCNTs could be grown even at an ambient ethanol pressure of 1×10−5Pa. Raman spectroscopy measurements showed that the G/Si ratios of SWCNTs grown at 700°C with the Pt catalyst under an ethanol pressure between 1×10−4 and 1×10−1Pa was larger than that grown with Co catalyst under optimal conditions (700°C, 1×10−1Pa), indicating that the Pt catalyst is suitable for SWCNT growth under a low ethanol pressure. In addition, the diameter distributions of SWCNTs grown with the Pt catalyst were narrower than those grown with the Co catalyst. Taking into account the results by transmission electron microscopy observation, the diameter reduction was caused by the smaller migration distance of Pt on the substrate. Based on these results, we discuss the growth mechanism of SWCNTs from the Pt catalyst.