Carbon Nanotubes in Nanoelectronics

Carbon nanotubes hold promise as basic components for nanoelectronics—they can be conductors, semiconductors and insulators. In 2001 IBM made the most basic logic element, a NOT gate, out of a single nanotube, and researchers in Holland created a variety of more complex structures out of collections of tubes, including memory elements. Recently IBM created nanotube transistors that outperformed the best silicon devices available. There are two big hurdles to overcome for nanotube-based electronics. One is connectibility—it's one thing making a nanotube transistor, it's another to connect millions of them up together. The other is the ability to ramp up to mass production. Traditional lithographic techniques are based on very expensive masks that can then be used to print vast numbers of circuits, bringing the cost per transistor down to one five-hundredth of a US cent. Current approaches to nanotube electronics are typically one-component-at-a-time, which cannot prove economical. Molecular electronics (which, strictly speaking, includes nanotubes) faces similar scaling hurdles. There are some possible solutions, however.