NIST 'Sandwich' Brings Molecular Switches Closer

Microprocessor architects have hoped for a long time that a day will come when molecule-sized electronic components will become readily available and fit for implementation in next-gen devices. Scientists at the National Institute for Standards and Technology (NIST) have recently developed a new, small-scale “sandwich,” made up of organic molecules, silicon and metal, which brings that day a little closer. Their innovation is explained in the August 11th issue of the respected Journal of the American Chemical Society.

The experts, joined by colleagues from the University of Maryland, may have just created the ultimate electronic component for the industry, authorities in the field say. Molecular switches represent the last level of miniaturization in the current technology, they add. The devices are able to carry more information than their silicon counterparts, and do so faster and with less power requirements. The only thing that has prevented their introduction until now has been a key step in the production process, when forces needed to apply them to electrical contact damaged the organic components substantially.

In order for the metal to be deposited onto the circuits, it first has to be heated to high temperatures, until it evaporates. Then, it is allowed to slowly settle on the contacts in the desired quantities. But the enormous temperatures wrecked havoc in the organic molecules. “Imagine what hot steam would do to your arm. Evaporated metal is much hotter, and organic switching molecules are very fragile – they can’t stand the heat,” NIST materials scientist Mariona Coll Bau explains.

Bau's team found an ingenious way of moving past these difficulties. The researchers attached a non-sticky material to the basic surface of the circuit. Then, they followed the usual process to deposit gold on top of it. Once the temperatures dropped to acceptable levels, the non-sticky material, with the laminated gold on top of it, was peeled off, exposing the layer underneath. Organic molecules were then added to the underside of the material, which was afterwards placed in its original position. This resulted in a sandwich-like structure, with the organic molecule caught between the original layer and the laminated gold.

The work was made possible by a new pressing machine, which is able to deliver the exact requirements of working with small and delicate components. “The machine allows us to press the three layers together so the organic molecules contact both the silicon and gold, but without smashing or otherwise degrading them,” Bau explains. “The technique may prove useful as a fabrication paradigm. It’s hard to make small things, and this might be an easier way to make them,” she concludes.