IBM Marks Breakthrough in Molecular Electronics

By Roy Mark  |  Posted 2009-06-12 Print this article Print

IBM scientists directly measure charge states of atoms using an atomic force microscope armed with a sensitive tuning fork tip to attain a milestone that opens up new possibilities in molecular electronics. The results hold potential to also impact a variety of fields such as catalysis or photovoltaics.

IBM scientists have demonstrated the ability to measure the charge state of individual atoms using non-contact atomic force microscopy. By measuring with the precision of a single electron charge and nanometer lateral resolution, researchers succeeded in distinguishing neutral atoms from positively or negatively charged ones.

The milestone, developed in collaboration with the University of Regensburg, Germany, and Utrecht University, Netherlands,  opens up new possibilities in the exploration of nanoscale structures and devices at the ultimate atomic and molecular limits. The results hold potential to impact a variety of fields such as molecular electronics, catalysis or photovoltaics.

To conduct the experiments, researchers used a combined STM (scanning tunneling microscope) and AFM (atomic force microscope) operated in vacuum at very low temperature (minus 451 degrees Fahrenheit) to achieve the high stability necessary for the measurements. The AFM uses a sharp tip mounted on one prong of a common tuning fork with the other prong being fixed to measure the attractive forces between the tip and the atoms on a substrate.

Molecular electronics, which aims at using molecules as functional building blocks for future computing devices, as well as for single-electron devices, an insulating substrate is needed in order to avoid the leakage of electrons. This makes non-contact atomic force microscopy the investigation method of choice. Scientists predict future computing elements will be vastly smaller, faster and more energy-efficient than today's processors and memory devices.

To study the charge transfer in molecule complexes, scientists think single atoms could be connected with molecules to form metal-molecular networks. Using the tuning fork tip for charging these atoms, scientists could then inject electrons into the system and measure their distribution directly with the non-contact AFM.

"The AFM with single-electron-charge sensitivity is a powerful tool to explore the charge transfer in molecule complexes, providing us with crucial insights and new physics to what might one day lead to revolutionary computing devices and concepts," Gerhard Meyer, who leads the STM- and AFM-related research efforts at IBM's Zurich Research Laboratory, said in a statement.

IBM researcher Leo Gross told eWEEK the milestone also holds promise for other areas of impact beyond nanoscale computing.

"The charge state and charge distribution are critical in catalysis and photoconversion. Mapping the charge distribution on the atomic scale might deliver insight into fundamental processes in these fields," Gross said.

The IBM breakthrough continues Big Blue's continuing work in the nanotechnology field.

IBM Fellows Gerd Binnig and Heinrich Rohrer at IBM's Zurich Research Laboratory won the 1986 Nobel Prize in Physics for using the STM to image and manage individual atoms. The AFM, an offspring of the STM and widely regarded as the instrument that opened the door to nanotechnology, was developed by Binnig in 1986.


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