By: Wei Xiong
Scientists and engineers over the world have thought for years that the next generation of smaller, more-efficient electronic and photonic devices could be based on the use of carbon nanotubes (CNTs), structures 10,000 times thinner than a human hair but with tremendous potential.
Although significant progress has been made in the carbon nanotube synthesis with various methods such as arc discharge, laser ablation, and chemical vapor deposition (CVD), there is still a big gap between high efficient carbon nanotube synthesis and the fabrication of CNT-based devices. The problem has always been finding a way to precisely integrate carbon nanotubes with other nano-scale structures.
Previous efforts in this area by other research groups tried to use advanced instrumentation to manipulate carbon nanotubes after growth. However, that approach is only good for research purposes but not suitable for large-scale fabrication of CNT-based devices because it is time consuming and expensive.
In the presentation, we will demonstrate a pathway to a solution with little or no manipulation necessary. Our method involves the application of optical near-field effects in a laser-assisted CVD process, by which simultaneous growth of Single Walled Nano Tube (SWNT)-bridge arrays with precise location and orientation control can be achieved at a relatively low temperature. Our study shows that the localized thermal enhancement induced by optical near-field effects and an external electric field enabled the SWNT growth with precise control of growth sites and orientations. Furthermore, laser polarization also shows significant influence on the control of growth site for SWNTs.
Superior to the previous methods that manipulate carbon nanotubes one piece at a time with expensive instrumentation and tedious processes, the new method can make multiple self-aligned SWNT bridges in a one-step process. The laser-based growth process opens up a new route for controlled SWNT integration that can lead to applications in nano-devices such as biosensors, light emitters, photon sensors, molecular motors and memory cells.
Fig. 1 Illustration of laser-assisted chemical vapor deposition for self-aligned growth of a single-walled carbon nanotube bridge using optical near-field effects.
The above brief overview was extracted from its original abstract and paper presented at The International Congress on Applications of Lasers & Electro-Optics (ICALEO) in Orlando, FL. To order a copy of the complete proceedings from this conference click here