Dendrimer-Assisted Low-Temperature Growth of Carbon Nanotubes by Plasma-Enhanced Chemical Vapor Deposition
Placidus B. Amama1, Oluwaseyi Ogebule2, Matthew R. Maschmann3, Timothy D. Sands3, and Timothy S. Fisher3. (1) Materials & Manufacturing Directorate, UTC/ Wright Patterson Air Force Research Laboratory, 2941 Hobson Way, Dayton, OH 45433, (2) Department of Chemistry, Alabama A&M University, Normal, AL 35762, (3) Purdue University, 1205 W. State Street, West Lafayette, IN 47907-2057
For applications of carbon nanotubes (CNTs) in certain areas of microelectronics and biomolecular electronics, it is desirable to be able to grow CNTs on sensitive substrates such as plastics. This requires the growth of CNTs at temperatures lower than the conventional temperature range for CVD systems (600 – 1000 °C). Using a shielded growth approach with plasma power in the range of 200 – 500 W, single-wall carbon nanotubes (SWNTs) / multiwall carbon nanotubes (MWNTs) and carbon nanofibers (CNFs) were successfully grown by microwave plasma-enhanced CVD (PECVD) from naked Fe2O3 catalyst supported on SiO2/Si substrates at 400 and 200 °C, respectively. The catalyst composed of nearly monodispersed Fe2O3 nanoparticles synthesized by interdendritic encapsulation and stabilization of Fe3+ species within fourth generation poly (amidoamine) (PAMAM) dendrimers. Mild calcination of the composite yielded naked Fe2O3 nanoparticles that showed high selectivity to CNTs at low temperatures, when shielded from the plasma.