Tuesday, May 25, 2010

US Patent 7719032 - MWCNT transistor


Multiwall carbon nanotubes tend to have metallic rather than semiconductor electronic properties and thus have conventionally been considered inappropriate to form transistor channels. However, this patent from Sony teaches a way to use the inner carbon shell as the electrode contact and the outer carbon shell as a semiconductor channel which may allow multiwall carbon nanotube transistors (although mass production could be problematic).
Claim 5 reads:

5. An electronic device including a multi-walled carbon nanotube having at least two layers, the electronic device comprising:

a field effect transistor comprising:

an outer carbon nanotube having semiconductivity;

an inner carbon nanotube that is partially included in the outer carbon nanotube;

a current-input terminal that inputs current to the outer carbon nanotube;

a current-output terminal that outputs current from the outer carbon nanotube; and

an electrode in contact with the inner carbon nanotube and applying voltage to the inner carbon nanotube to control operation of a conduction channel of the field effect transistor formed in the outer carbon nanotube between the current-input terminal and the current-output terminal.