Organic transistors get small

Organic thin film transistors are cheaper and more flexible than the silicon transistors used in today's computer chips. Researchers are working to make organic transistors smaller and more efficient for use in applications like smart tags and computer displays.

Researchers from Cornell University have shown that it is possible to fabricate useful organic thin film transistors that have a channel length as small as 30 nanometers. The smaller the channel, the faster the transistor.

Previous attempts at making smaller organic thin film transistors were limited to about 100 nanometer channel lengths, or a little larger than the channel length of today's standard silicon transistor; below this size organic transistor performance tended to degrade, according to the researchers. A nanometer is the span of 10 hydrogen atoms.

A transistor turns on when electric current flows from a source electrode through a channel to a drain electrode. A third, gate electrode controls the flow.

The researchers made the tiny organic transistor from pentacene using electron beam lithography, which employs chemicals and streams of electrons to etch minuscule shapes. Electron beam lithography is a relatively expensive process, but the work shows that organic transistors can be scaled to small sizes.

Organic thin film transistors could be used in practical applications in five to ten years, according to the researchers. The work appeared in the October 2, 2003 issue of Advanced Materials.