AVS 50th International Symposium
    Nanotubes Thursday Sessions
       Session NT-ThM

Invited Paper NT-ThM3
Growth & Control Mechanisms for Directed Assembly of Vertically Aligned Carbon Nanofibers: Fundamental Studies and Nanotech. Applications

Thursday, November 6, 2003, 9:00 am, Room 317

Session: Nanotube Growth and Processing
Presenter: D.H. Lowndes, ORNL
Authors: D.H. Lowndes, ORNL
V.I. Merkulov, ORNL
A.V. Melechko, ORNL, U. Tennessee
M.A. Guillorn, ORNL
M.L. Simpson, ORNL, U. Tennessee
H. Cui, ORNL
J. Liu, Duke U.
J.B.O. Caughman, ORNL
M.J. Doktycz, ORNL
T.E. McKnight, ORNL
L. Zhang, ORNL, U. Tennessee
X. Yang, ORNL, U. Tennessee
D.K. Hensley, ORNL
Correspondent: Click to Email
Although vertically aligned carbon nanofibers (VACNFs) are structurally quite imperfect in comparison to single-wall carbon nanotubes (SWNTs), their synthesis and assembly is highly controllable using a DC plasma-enhanced method and--unlike SWNTs-- they can be precisely positioned in large arrays. VACNFs grow simultaneously by two mechanisms, catalytically controlled vertical growth and defect-mediated lateral growth, and the morphology of isolated VACNFs is readily controlled. Their growth rate can be increased by changing the feedstock transport from diffusive to forced flow, and their growth mode can be altered from 'base-type' to 'tip-type' without changing the type of substrate or catalyst. Their alignment angle relative to the substrate also can be controlled via the direction of local plasma electric-field lines, so that deliberately tilted or kinked CNFs can be grown. Recent extensions to grow VACNFs using radio frequency (RF) PECVD and from nanometer-scale metal catalyst particles also will be described. Phenomenological models that explain important aspects of VACNF growth will be presented and validated with experimental results. Potential nanotechnology applications of VACNFs will be demonstrated, including multi-electrode vacuum nanoelectronic devices using field emitting VACNF cathodes; tubular nanopipes that can be deterministically positioned using VACNFs as templates; the use of VACNFs as an intracellular interface for monitoring and controlled biochemical manipulation of phenomena within viable cells; and their use to form semi-permeable membranes that mimic some features of biological cells, in combination with microfluidic and electronic structures.