Carbon Nanotubes (CNT) may one day replace the silicon we use for semiconductors. Although it is roughly 15 years since the first CNT transistor was demonstrated they have not been successfully fabricated on a wafer scale until now. The reason it has taken so long is that semiconducting CNTs are not as well behaved as silicon. Firstly when they are grown it is difficult to get them to line up in a regular grid pattern which is essential for correct interconnectivity. Secondly during fabrication some of the semiconducting elements become metallic so they effectively act as a short to the supply rails.


A team of Engineers at Stanford University have managed to reduce the incidence of misaligned cells to just 0.5 % and to eradicate metallic elements by turning off all the good transistors and applying a voltage across the supply rails to vaporize them.


They went on to use the wafer to build a rudimentary processor using just 178 transistors. It performs counting and number sorting and as a demonstration of its potential, the researchers showed that it could run MIPS, a commercial instruction set developed in the early 1980s.