The promise of carbon nanotubes become realized when these small cylinders are attached to electrically conductive surfaces. To date this has not been the case: researchers have only been able to create high-resistance interfaces between nanotubes and substrates. How things change. A team from Rensselaer Polytechnic Institute has developed two techniques that places carbon nanotube patterns on metal surfaces.
The first method is called “floating catalyst chemical vapor deposition” where a carbon-rich compound is heated to very high temperatures until the material vaporizes. When the vapor cools, carbon is deposited directly on a Inconel (a nickel-based super alloy with good electrical conductivity) substrate in the form of nanotube arrays. This simple, single-step process allows nanotubes to attach to the surface with tremendous strengh, the electrical contact established between the two materials are excellent, and nanotubes can be grown on substrates with any shape.
The second method does not rely on such a high temperature process that can be incompatible with substrates that are not as temperature resilient as Inconel. The process involves contact printing methods. First, carbon nanotube patterns are grown on silicon surfaces using chemical vapor deposition and then transferred to a solder-coated metail surface. Solder, a metal alloy, is used to join metallic surfaces and has a low melting point. The nanotube patterns stick to the solder at relatively low temperatures.
Not only can carbon nanotubes be used for interconnects, they have a field emission property where electrons are pulled out from the surface when a voltage is applied. The field emission property of carbon nanotubes combined with metals can potentially lead to electronic displays.
For more information: Photonics Online