Synthesis of carbon clusters and thin films by low temperature plasma chemical vapor deposition under atmospheric pressure

Abstract

We have developed a torch-type plasma generator to make low temperature material processings possible in open air conditions. The cylindrical plasma CVD apparatus is composed of a metal needle acting as the cathode at the center and a grounded cylindrical anode. The inner surface of the anode was lined by a thin insulator nozzle. A low temperature homogenous plasma was generated by applying rf voltage to the needle cathode under a constant flow of atmospheric pressure He or Ar. The plasma generated in the insulator nozzle was released to open air. This cold plasma torch has been verified to be applicable for various plasma processings. Fullerene was found to be formed by the analyses with HPLC and TOP-MS in the soot produced by introducing a vaporized aromatic hydrocarbon into the after-glow region of the plasma with Te and Tg at about 1.9eV and 400°C, respectively. Different from the conventionally employed arc-plasma, which decompose graphite into fullerenes at much higher temperatures, this is a polycondensation reaction that wraps up small molecules into a large molecule. We examined the possibility of using this plasma for encapsulating or incorporating hetero-atom(s) in the fullerene. The plasma was successfully employed for the deposition of such inorganic thin films as glassy carbon, SiO2, and TiO2 in open air environment.