(Left) Nanotube transistor image (Right) Nanotube transistor concept (via IBM)
Carbon Nanotubes (CN) is a material that will foster a technological shift in the coming years. More recently CNs have been used to create flexible circuit boards, advanced sensors, a 9 nanometer transistor, and they were even applied with a pencil. When giants such as IBM look into fabrication of the material, it is time to listen.
As physical limitations are being reached as to how small silicon transistors can be made, a dream in the scientific community is to figure out how to use these incredible nanotubes to make faster and smaller transistors. Using new chip design architectures, nanotube transistors will offer less resistance to electrons and could be manufactured in the atomic scale. IBM demonstrated this year that carbon transistors are successful and can be smaller than 10nm (less than half the size of a silicon transistor).
IBM researcher Hongsik Park holding different solutions of carbon nanotubes (via IBM)
To achieve a CN transistor, we must find a way to make and precisely orient billions of ultra pure nanotubes (currently only about a hundred can be placed at one time). IBM developed a method that uses ion-exchange chemistry to do this. The CNs are first isolated in a solution of surfactant, a kind of soap to make them water-soluble. They made a substrate that contains “trenches” made of chemically modified hafnium oxide (HfO2) and surrounded by silicon oxide (SiO2). This substrate is then submerged in the carbon nanotube solution and the individual nanotubes align as they bond to the HfO2 trenches only.
Using this method, IBM researchers precisely deposited over 10,000 nanotubes at a time which will give densities of a billion per cm^2.
IBM’s arsenal of resources is apt to tackle the development of carbon nanotube transistors. They stated that the rapid testing of thousands of devices could be done using regular characterization tools, due to their nanotube process is compatible with standard commercial processes. This is certainly timely news for carbon transistors, although there is no timetable yet, the industry is headeeed in that direction rapidly.