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January 31, 2007

Electronic Devices Based on Purified Carbon Nanotubes

Danvers Johnston, an Integrative Graduate Education and Research Traineeship (IGERT) program fellow, is seen here working in the lab at the Nano/Bio Interface Center at the University of Pennsylvania.

The oven pictured here reaches temperatures exceeding 1000 degrees Celsius and is used for chemical vapor deposition growth of single-walled carbon nanotubes. Johnston creates the nanotubes by reacting methane and hydrogen gas with nanometer-diameter iron catalyst particles. These nanotubes are approximately 1 nanometer in diameter and many thousands of nanometers in length. They have excellent electrical conducting and semiconducting properties for use in high-performance transistors and sensors.

This work is significant because it may be an important step on the way to using carbon nanotubes in electronics. Traditionally, carbon nanotubes are grown directly on a substrate, such as a silicon chip. However, this method yields a certain percentage of nanotubes without the desirable properties for electronic devices. In the method used by Johnston, et al, commercially available raw nanotube material is first purifed and then suspended in water. Then, a functionalized silicon chip is dipped in the solution. The important point is that the creation of a stable suspension of purified nanotubes opens the door for other solution-based methods that could one day be used to sort the nanotubes and select those that exhibit desired properties.

Tests on the chip show that the nanotubes "retain the unique electronic properties that make them leading candidates for nanoelectronic devices," according to the letter in Nature Materials. Commercial use of carbon nanotubes in electronics is probably a decade or more in the future, but the potential of these tiny materials to impact many industries is there.

This research was supported by National Science Foundation grants DMR 04-25780 and DGE 02-21664. To learn more about the NSF IGERT Program, visit the IGERT Home page. (Date of Image: Oct. 14, 2005)

Credit: The Nano/Bio Interface Center at the University of Pennsylvania

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