World’s Smallest Single-Atom Transistor Functions at Room Temperature, Sans Semiconductor

August 23, 2018 by David Jones

Researchers from the Karlsruhe Institute of Technology in Germany have announced a working single-atom transistor that operates at room temperature without a semiconductor present.

Researchers have created a transistor that uses no semiconducting material and operates at room temperature—at just one silver atom across.

Researchers at the Karlsruhe Institute of Technology (KIT) in Germany announced what they say is a breakthrough in micro-electronics, creating a single-atom transistor that they claim is the smallest in the world.

The transistor, which operates in a gel electrolyte, works at room temperature and operates on extremely low energy consumption, according to the research team led by Dr. Thomas Schimmel, a physicist at the Institute of Applied Physics at Karlsruhe (APH).

“This quantum electronics element enables switching energies smaller than those of conventional silicon technologies by a factor of 10,000,” Schimmel, an expert in physics and nanotechnology, said in a statement.


The transistor and the gel electrolyte are shown above. Image used courtesy of Professor Thomas Schimmel / KIT


Schimmel, who does research at the APH, the Institute of Nanotechnology, and the Material Research Center for Energy Systems (MZE) of KIT is widely considered the pioneer of single atom electronics. Earlier this year, he was named co-director of the Center for Single-Atom Electronics and Phonetics, a center established in partnership between KIT and ETH Zurich.

The researchers said the single atom transistor works using an entirely new technical approach, as no semiconductors are used and the transistor is made entirely of metal, which they say allows very low electrical voltage and low power consumption.

This is a continuation of research done by Schimmel and others for KIT, announced as a single-atom transistor based on silver in 2010.


A representation of a concept from Schimmel's 2010 research on the single-atom transistor using a silver atom. Image used courtesy of KIT.


Atom-Level Transistors at Room Temperature

Gerhard Klimech, a professor of electrical and computer engineering at Purdue University, said the potential breakthrough here would be the fact researchers were able to achieve these results without using subfreezing temperatures.

“If it’s true they are doing this at room temperature, its a huge achievement,” he said.

In 2012,  Klimeck was part of an international team of researchers, including Purdue, the University of New South Wales, the University Melbourne, and the University of Sydney, who developed what was then considered the world’s smallest transistor using a single phosphorus atom. At that time, the single-atom transistor had to be kept in a state of extreme cold, or the equivalent of liquid nitrogen, at minus 391 degrees Fahrenheit (minus 196 degrees Celsius).

At the time, Intel’s most advanced chip, called the Sandy Bridge, used a manufacturing process that placed 2.3 billion transistors 32 nanometers apart. The single phosphorus atom, however, was only 0.1 nanometers across.

Klimeck, however, did raise questions about exactly how much more computing you could do because of the way single atoms charge.

Scott Dunham, a professor of electrical engineering at the University of Washington, questioned whether the announcement actually overhyped the work done by the researchers. He says the claim that you can get a factor of 10,000 power, you would have to reduce the voltage by a factor of 100.

“The current device is far from single-atom,” he said. “The other thing is their switching times are in seconds, which is pretty absurd.”

Rob Enderle, principal analyst with the Enderle Group, says the announcement could eventually lead to dramatic changes in everything from sensors to mainframes, but cautioned that any tangible updates in these products remain years into the future.

“This is a proof of concept, which typically would mean production would be at least five, but more likely 10 years or more out in products that you could buy,” he wrote in an email.

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