Method tests molecular devices

Smaller electrical components enable smaller, faster computers and new devices like microscopic sensors. One long-term approach to finding ways to make electronic components smaller is to make them from single molecules.

Components made from molecules are likely to be smaller than those that can be made using today's chip fabrication methods, and they can potentially self-assemble, which would make for inexpensive manufacturing processes.

Researchers from Purdue University have taken a step toward molecular components with a method for evaluating the room-temperature efficiency of transistors made from molecules.

When electrical devices are scaled down to the dimensions of molecules, their behavior often differs radically from their larger counterparts. The researchers' method makes it possible to understand exactly how a transistor may function and what its limitations are in order to figure out ways around those limitations.

The researchers' method provides a consistent way to evaluate the conductance of different mechanisms in molecular transistors. A single module can be used as the semiconductor channel in a field-effect transistor in three ways: using an electric field to change the molecule's conductance, which is how silicon transistors work; reversibly changing the molecule's shape to break contact with electrodes; and changing the molecule's shape to alter its internal conductance. All of the approaches involve trade-offs.

The evaluation method could be used to design devices like molecular sensors within ten years, according to the researchers. The work appeared in the April 14, 2004 issue of Nano Letters.