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Techniques Pave Way for Carbon Nanotubes in Electronic Devices

Carbon nanotubes offer promising applications in fields ranging from electronics to biotechnology. Photo by Swastik Kar
A Rensselaer team recently reported two new techniques for placing carbon nanotube patterns on metal surfaces of just about any shape and size. Their methods could help overcome some of the key hurdles to using carbon nanotubes in computer chips, displays, sensors, and many other electronic devices.

The super-tiny cylinders offer promising applications in fields ranging from electronics to biotechnology, but since many of these applications are based on the superior conductivity of carbon nanotubes, good contact between nano-tubes and conducting metal components is essential.

As chip makers seek to continually increase computing power, they are looking to shrink the dimensions of chip components to the nanometer scale. Communication between components becomes increasingly difficult at this incredibly small scale, making carbon nanotubes a natural choice to replace metal wires, according to the researchers. Both of the newly developed techniques could bring the use of nanotubes as interconnects on computer chips closer to reality.

The first technique — dubbed “floating catalyst chemical vapor deposition” — involves heating a carbon-rich compound at extremely high temperatures until the material vaporizes. As the system cools, carbon deposits directly on the metal surface in the form of nanotube arrays.

In the single-step process, nanotubes attach to the surface with much greater strength, and excellent electrical contact is established between the two materials. Chemical vapor deposition is a high-temperature process, however, which makes it incompatible with some sensitive electronic applications.

The Rensselaer team worked with a staff research engineer in the Components Research Division at Intel Corporation to develop an alternative procedure that mimics the way photographs are printed from a film negative. They first grow patterns of carbon nanotubes on silicon surfaces using chemical vapor deposition, and then the nanotubes are transferred to metal surfaces that are coated with solder — a metal alloy that is melted to join metallic surfaces together. The nanotubes stick in the solder, maintaining their original arrangement on the new surface.

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