Grants and Contracts Details
Description
Although carbon nanotubes (CNTs) have emerged as a viable nano-material, it is still difficult to utilize
them for fabrication of nanoelectronic devices and nano-electromechanical system (NEMS), because most
nanotubes are grown as random and entangled strings on substrates. Recently, successful growth of
vertically aligned multi-walled nanotubes (MWNTs) through the anodized aluminum oxide (AAO) nanoporous
template has attracted engineers' interests. This is because both the diameter and the length of
nanotubes are controllable by using the template and also the Ah03 template provides a perfect insulating
material for isolation of conductive nanotubes from each other. Very recently, we successfully grew
vertically aligned MWNTs on silicon substrates through the AAO template. However, no method exists
for synthesis of horizontally aligned CNTsfrom AAO nano-templates on silicon substrates.
In this exploratory research proposal, building upon our vertically aligned CNTs, we aim to achieve
growth of horizontally aligned CNTs through Ah03 nano-porous template, where arrays of cylindrical
nano-pores are horizontally aligned on silicon substrate. The eventual goal is to achieve a onedimensional
(I-D) array of CNTs horizontally aligned on substrate. There are two thrusts in this research.
In the first thrust, fabrication of horizontal arrays of cylindrical pores by anodic oxidation of aluminum
will be carried out through geometric and electric field modulation. To achieve horizontal nano-pores,
anodization happens at one side of the aluminum film and penetrates into aluminum horizontally. If the
thickness of aluminum is adjusted to the size of a single cell (- a few hundred nanometers), formation of a
I-D array of nano porous channels is expected. In the second thrust of research, growth of CNTs can be
carried out using the horizontally aligned nano-pores as templates and eventually a I-D array of CNTs
horizontally aligned on silicon substrate can be achieved. Study of mechanisms for the pore and cell
formation suggests that the well-organized porous structure is caused by the non-uniform electric field
across the barrier layer due to its scallop shape. In the steady state, the field-assisted dissolution rate of the
pore base equals the field-assisted growth rate of oxide at the Allbarrier-Iayer boundary, so that the pore
formation propagates steadily with constant barrier thickness. In the steady state, the electric field forces
the radius of pores, the barrier layer and the angle of the scallop to be constant through "Self-Adjusting
Effect". Further analysis of electric fields in the sandwiched aluminum film suggests the feasibility for
growth of a I-D array of nanopores, and thus growth of a I-D array of CNTs.
The proposed research will improve the capability for basic and applied research, enhance
multidisciplinary research, and educate tomorrow's scientists and engineers in nanotechnology. The
research proposed here would lay a foundation for carbon nanotube-based nano-electromechanical system
(NEMS) that integrates the carbon nanotube-based devices with microcircuits and carbon nanotube-based
nanoelectronic devices. The outcome of this research may lead to revolutionary fabrication technology for
transistors, molecular electronic devices, and quantum devices.
Status | Finished |
---|---|
Effective start/end date | 11/1/03 → 4/30/05 |
Funding
- KY Science and Technology Co Inc: $14,926.00
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