A carbon nanotube (CNT) computer has been built for the first time, by a team of Stanford School of Engineering researchers, the university said today.
The technology promises electronic devices that run faster and use less energy than those made with silicon chips.
Until now however, it has been difficult to achieve consistent production of CNTs, with some tubes not growing in straight lines and others behaving like metallic wires instead of like semiconductors.
Now the researchers say methods to burn up and get rid of the metallic CNTs, which conduct electricity all the time, have been devised along with an algorithm to map out a circuit layout that works even though some tubes are askew.
The team, led by professors Subhasish Mitra and H S Philip Wong built a basic computer out of CNTs, with 178 transistors, as many as are possible with Stanford's limited chip fabrication laboratory.
Fully functional, the CNT computer can run the MIPS instruction set from the early 1980s.
There are several efforts underway to find a replacement technology for today's silicon-based semiconductors, as they reach the practical end of shrinking sizes and consume too much energy.
Graphene, or carbon atoms set in a honeycomb pattern, holds promise as a semiconductor material to replace silicon. Stanford Engineering school researchers Zhenan Bao, Anatolyi Sokolov and Fung Ling Yap are working on using deoxyribonucleic acid (DNA) strands to grow narrow ribbons of graphene, so as to assemble transistors.
The graphene ribbons are just one atom thick and 20 to 50 atoms wide, making assembly "a significant challenge," according to Sokolov.
However, by using a silicon support substrate into a solution of DNA derived from bacteria and using the molecule, which containts the blueprint for how all known living organisms develop and function, the researchers were able to construct a chemical process that created carbon ribbons.
According to Yap, the DNA-based fabrication method is highly scalable, with high resolution and low manufacturing cost.