IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Nanotubes: Science and Applications Topical Conference Thursday Sessions
       Session NT+EL+NS-ThM

Paper NT+EL+NS-ThM1
Control of Carbon Nanofiber Growth: "Base" versus "Tip" Growth Regimes

Thursday, November 1, 2001, 8:20 am, Room 133

Session: Nanotubes: Growth, Functionalization, and Sensors
Presenter: A.V. Melechko, University of Tennessee
Authors: A.V. Melechko, University of Tennessee
V.I. Merkulov, Oak Ridge National Lab
M.A. Guillorn, University of Tennesse and Oak Ridge National Lab
D.H. Lowndes, Oak Ridge National Lab
M.L. Simpson, University of Tennesse and Oak Ridge National Lab
Correspondent: Click to Email
Carbon nanofibers (CNF) show promise for many applications in such new areas as nanoelectronics and nanobiotechnology. It is very important to have a precise control of the position, orientation, and shape of the CNFs to maximize their utility for these applications. Recently it became possible to achieve such deterministic growth by nanopatterning catalyst and using Plasma Enhanced Chemical Vapor Deposition (PECVD). PECVD is a complex process that involves control of many interdependent parameters such as pressure, mass flow ratio (C2H2/NH3), substrate temperature, substrate material, plasma intensity and bias. Two different CNF growth regimes have been observed. One is when the catalyst particle is detached from the substrate surface and located at the tip of the CNF ("tip-growth" regime). Another regime is when the catalyst particle stays attached to the substrate ("base-growth" regime). We present an experimental study of the parameter space of a DC PECVD process for different regimes of CNF growth: "base-growth", "tip-growth", and intermediate regimes, where both types of CNFs were observed simultaneously. The mechanisms, which are responsible for the competition of these different growth phases, such as catalyst-substrate interaction and interdiffusion, formation of amorphous carbon film, and kinetics of catalysis and carbon diffusion through catalyst particle will be discussed.