Researchers at the U.S. Department of Energy's Lawrence Berkeley National Laboratory and Columbia University have demonstrated that electrical resistance via a molecular junction can be turned "on" or "off" by pushing and pulling the junction, and this feature could potentially be used as a switch in future nanoelectronics. The junction is a nanometer-scale circuit element that contacts gold atoms with a single molecule.
Jeff Neaton with the Molecular Foundry's Theory of Nanostructured Materials Facility says that "for these sub-nanometer scale junctions — just a handful of atoms — theory can be valuable in helping interpret and understand resistance measurements."
At the nanoscale, electrons can travel via quantum tunneling, in which it is possible for a particle to disappear through an energy barrier and suddenly appear on the other side, without any energy expenditure. The researchers recently learned that the conductance of amine-containing molecules in contact with gold electrodes could be reliably measured, and then launched a study of the conductance of a junction between gold electrodes and bipyridine. Neaton and postdoctoral researcher Su Ying Quek put together a hypothesis capable of describing the conductance of junctions arranged vertically between two gold molecules and sandwiched at angles. They discovered that current flow was greater when bonded at an angle compared to a vertical bond, and further investigation revealed that pushing the junction into a vertical configuration activates electrical resistance while pulling the junction into an angled configuration cuts it off. "Organic-inorganic interfaces are everywhere in nanoscience, and developing a better picture of charge transport in hybrid materials systems will certainly lead to the discovery of new and improved electronic devices," Neaton says.
From Berkeley Lab News Center
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