Structure of a Molecular-Scale Circuit Component

As technology becomes more and more advanced, many electronic gadgets that define the modern world have become steadily smaller and more powerful. Digital music players, computers, cellular phones — all have become more compact and better performing as researchers learn to make tinier, faster circuits. Now, many scientists, including a team of researchers at Brookhaven, are beginning to learn how to make remarkably small molecular-scale circuit components.

The BNL team has determined the molecular structure of an experimental, organic compound-based circuit component that is only a few nanometers (billionths of a meter) in dimension. Their work may help scientists understand how the structure of these components, known as “molecular electronic junctions,” relates to their performance and function. Moreover, in the longer term, this work may help incorporate these and other molecular-scale devices into a new generation of electronics-based technologies.

A New Frontier

“Molecular electronics is a very exciting developing field, since these extremely small circuits, based on organic molecules rather than metal, have a potentially greater circuit density than conventional silicon-based technology. This means that more circuits could fit on one circuit board, leading to electronic devices that are much smaller than those currently produced,” said one of the study’s lead scientists, Brookhaven physicist Julian Baumert (pictured on left in photo above). “We’re interested in the structure of the junction — how the molecules are oriented and packed together — because it is linked to the function and performance of the circuit.”

In conventional circuits, junctions are commonly made of two different types of silicon that, when layered together, allow electric current to flow in one direction only. Here, the junction under study consists of two very thin layers of two different organic compounds — “alkyl-thiol” and “alkyl-silane.” They are sandwiched on one side by a layer of solid silicon and on the other side by a layer of liquid mercury, which serve as electrodes. Alkyl-thiol and alkyl-silane molecules have simple structures (making them fairly easy to study) and the potential to be good insulating materials (a desirable property in many junctions).

EDITOR’S NOTE: In June 2006, Brookhaven scientist Julian Baumert died of melanoma at the age of 31.