Nanotube transistor has power

The key to faster electronics is making electrical components smaller. Along those lines, researchers are working to make components from carbon nanotubes, which are rolled-up sheets of carbon atoms that can be smaller than a nanometer in diameter.

Researchers from Stanford University, Purdue University and Harvard University have advanced the field with a method for making sub-50-nanometer-long field-effect transistors from carbon nanotubes. The devices' tiny electrodes align automatically, and the transistors can handle the high currents necessary for speedy circuits.

The field-effect transistors could eventually be used in very fast, miniature circuits.

The devices are speedy because they are small enough to provide near-ballistic electron transport at room temperature, and they work with high-k dielectric insulators.

Electrons usually move through a transistor by bouncing off the sides of the electron channel. More efficient ballistic transport occurs when the channel is small enough to allow electrons to travel straight through.

High-k dielectric insulators hold the large amount of charge necessary to drive the gate electrodes that control small transistors.

The researchers' prototype of a string of eight transistors made from a single nanotube and an electrode array yields 150 millionths of an amp, or microamps, according to the researchers.

The researchers are working on several challenges that must be met before the nanotubes can be used as practical transistors, including precisely controlling the structure and alignment of the tiny components on a surface.

The method could be used to make practical electronic components in one or two decades, according to the researchers. The work appeared in the June 23, 2004 issue of Nano Letters.