AVS 51st International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS1-WeM

Paper PS1-WeM11
Gas-Phase Synthesis of Single-Walled Carbon Nanotubes by Hot-Filament-Assisted Plasma Chemical Vapor Deposition and Its Analysis by Mass Spectroscopy

Wednesday, November 17, 2004, 11:40 am, Room 213A

Session: Plasma in Nanoscale Applications
Presenter: Y. Hayashi, Kyoto Institute of Technology, Japan
Authors: Y. Hayashi, Kyoto Institute of Technology, Japan
Y. Morimoto, Kyoto Institute of Technology, Japan
Y. Kogawara, Kyoto Institute of Technology, Japan
S. Nishino, Kyoto Institute of Technology, Japan
Correspondent: Click to Email
Single-Walled Carbon Nanotubes (SWNTs) have been successfully synthesized in gas phase by Hot-Filament-Assisted Plasma Chemical Vapor Deposition. Hot filaments were used for heating a reaction zone and for the assistance of generation and stabilization of DC plasma. Ethylene diluted 30 % in hydrogen was flowed through a pipe into a stainless chamber to the direction of the hot filaments. The vapor of ferrocene was included into the reaction gas before introduction to the chamber. Three tungsten wires were stretched and they were heated 1800-2000 °C. The pressure in the chamber was maintained 3.33 kPa (25 Torr). At 25 mm downstream of gas flow from the hot filaments, a cupper plate was placed perpendicular to the flow. DC voltage of +300 V with the current of 150 mA was applied to the cupper plate with the hot filaments and the chamber grounded. Glow discharge plasma was generated between the hot filaments and the cupper plate for about one hour. Carbon fine particles collected on the plate as well as on another plate put under the plasma on the bottom of the chamber were evaluated by Raman spectroscopy and they were confirmed to be SWNTs. The diameter of the SWNTs were observed by transmission electron microscopy to be 1 to 2 nm. The fact that more SWNTs were obtained on the bottom plate than on the downstream plate suggests their synthesis in gas phase. Quadrupole mass spectrometry was carried out for the analysis of molecules during the synthesis. The evolution of partial pressure of benzene corresponded well with the evaporation of ferrocene while that of iron did not. The results support that iron clusters were formed in gas phase through the decomposition of ferrocene and that large amount of SWNTs were grown on them being suspended in the glow discharge plasma for a long time.