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Presenter: Badr Omrane, Ph.D. Candidate
Supervisor: Dr. Chris Papadopoulos

Date: Tue, December 8, 2009
Time: 14:00:00 - 15:00:00
Place: ECS 660

ABSTRACT

Abstract:

Despite the fact that much progress has been made during the last decade in understanding carbon nanotube growth mechanisms and in controlling their orientation through the use of different techniques, many problems still need to be addressed. Up to now, it remains highly challenging to precisely control nanotube orientation on Si and Si/SiO2 even when using an external electric field or gas flow. In addition, controlling carbon nanotube location, catalyst geometry and its effect on periodicity of the nanotube location and orientation have not been fully understood.

Two novel techniques were introduced for the controlled growth and assembly of carbon nanotubes as a way to address some of these challenges. Colloidal lithography using 450 nm diameter polystyrene nanospheres and direct-writing via nanopipettes were used to pattern carbon nanotube catalyst. Chemical vapor deposition of the produced structures using methane feedstock at 900 oC show single-walled carbon nanotubes in the patterned regions. These techniques allow precise nanoscale catalyst patterns to be directly defined for carbon nanotube growth in a simple and inexpensive manner suitable for device prototyping and applications. Two-terminal I-V measurements on the post-growth colloidal lithography and nanowriting samples were performed. Based on the numerical and experimental data, device performance has been attributed primarily to the contact resistance that includes Schottky barrier resistances and an interface resistance. The electronic transport results on colloidal lithography and nanowriting samples show the efficiency of these techniques for CNT device fabrication.