Hybrid nanowire makes transistor

One challenge in making minuscule electronic devices from nanoscale components is wiring the components together.

Conventional lithography techniques cannot produce metal contacts much smaller than 100 nanometers. These are an order of magnitude larger than components made from nanowires and nanotubes. A nanometer is one millionth of a millimeter, or the span of 10 hydrogen atoms.

Researchers from Harvard University have found a way to transform sections of semiconducting silicon nanowires into metallic, or conducting, nickel silicide. They used the process to produce hybrid semiconducting/metallic nanowires. Regular semiconducting nanowires can be used as transistors. The combination makes for a transistor complete with source and drain electrode contacts.

Closely-spaced nanowire lattices could lead to ultra-dense memory and logic circuits, according to the researchers.

The researchers used a perpendicular nanowire as a shadow mask to make a hybrid nanowire with a particularly short semiconductor section. The transistor's 20-nanometer long channel is comparable to the smallest channel that is possible to make using today's state-of-the-art chip-making techniques, according to the researchers.

The device's contact between semiconductor and wire is very precise -- an atomically-defined junction between silicon and nickel silicide. This will make for more consistent devices, and will also enable fundamental physics studies of electrical flow in nanostructures with atomic-level interfaces, according to the researchers.

The method could be used practically within a decade, according to the researchers. The work appeared in the July 1, 2004 issue of Nature.