Jul 13, 2010
Route to high-density horizontal CNT bundles
The use of carbon nanotubes in nanoelectronic devices and circuits often requires that the material is grown in a specific location and aligned in a particular direction. Progress has been made recently on the growth of well aligned carbon nanotubes on quartz or sapphire with a coverage of ~10 per micrometre, and scientists have been busy exploring other substrates.
Researchers from the Department of Electronic and Computer Engineering at Hong Kong University of Science and Technology (HKUST) have developed a technique to grow high-density horizontal carbon nanotubes on silicon. As shown in the image, the carbon nanotubes are well aligned in the horizontal direction. The scientists have demonstrated the growth of carbon nanotubes ranging from 12 to 103 tubes per micrometre by controlling the catalyst thickness. This growth technique has major ramifications on the use of carbon nanotubes for nanoelectronics, including next-generation integrated circuit interconnects and field effect transistors.
The HKUST team used the plasma-induced electric-field to guide the direction of the carbon nanotube growth. The plasma charging during PECVD growth created a plasma-induced electric-field at the interface between the substrate surface and plasma. The induced field is typically vertical relative to the substrate surface. To create a horizontal electric-field, the HKUST researchers designed micro-structures with insulating sidewalls.
More details can be found in the journal Nanotechnology.
About the author
Dr Yang Chai is a research associate at Hong Kong University of Science and Technology. He currently is working on the fabrication of carbon-related materials and carbon-based devices, including the testing and characterization of resulting prototypes. Dr Zhiyong Xiao and Prof. Philip C H Chan, the leader of the research group, also contributed to this research.