Controlled-growth of single-walled carbon nanotubes using optical near-field effects

Controlled growth of self-aligned single-walled carbon nanotubes (SWNTs) was realized using optical near-field effects in a laser-assisted chemical vapor deposition (LCVD) process. Electronic devices containing ultrashort suspended SWNT channels were successfully fabricated at relatively low substrate temperatures. According to the numerical simulations using High Frequency Structure Simulator (HFSS), significant local-heating enhancement occurred at electrode tip apexes under laser irradiation, which was about ten times higher than the rest part of the electrodes. Experimental results revealed that the localized heating enhancement at the electrode tip apexes significantly stimulates the growth of SWNTs at a significantly reduced substrate temperature compared with the conventional LCVD process. The near-field enhancement dependence on metallic film thickness and laser polarization was investigated through numerical simulation using HFSS, which provided a guideline for further optimization of maximum near-field enhancement. This technique suggests a viable laser-based strategy for fabricating SWNT-based devices at relatively low substrate temperatures in a precisely controlled manner using the nanoscale optical near-field effects, which paves the way for the mass production of SWNT-based devices using expanded laser beams.