Hyper-cold Electrons Could Mean Drastic Energy Savings

Scientists in Texas have found a method of cooling electrons to nearly absolute zero, and they’ve done it at room temperature. Their discovery could lead to electronic devices that need only about one-tenth as much energy as they do today, thereby dramatically reducing the size and weight of batteries.

“We are the first to effectively cool electrons at room temperature,” said Seong Jin Koh, an associate professor at the Materials Science and Engineering Department at the University of Texas (UT) at Arlington. “Researchers have done electron cooling before, but only when the entire device is immersed into an extremely cold cooling bath.”

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Now, Koh says, there’s no need for using liquid nitrogen or liquid helium in the process. In fact, he says, electrons in a chip, for instance, can undergo a natural process of thermal excitation, which heats them up, at an ambient temperature of about 70 degrees Fahrenheit, or room temperature. Likewise, he says, a room-temperature chip can cool them down too.

The chip in question is equipped with a nanoscale structure with several microscopic components, including what’s known as a “quantum well,” to suppress the excitation of the electrons, cooling them off.

Koh says cold electrons are the pathway to a new kind of transistor that requires very little energy to operate, and he adds, “Implementing our findings to fabricating energy-efficient transistors is currently under way.”

The team’s research, published Sept. 10 in Nature Communications, explains that a quantum well is a minuscule gap between two semiconducting materials. Electrons moving along the semiconductors reach this gap and try to enter it. But to do so they must have very low energy, that is, they must be very, very cold. Warmer electrons cannot enter the well.

The electrons that are admitted to the quantum well aren’t merely very cold; their temperature has been brought down to -378.4 degrees Fahrenheit, or a mere 81.29 degrees Fahrenheit above absolute zero, the temperature at which all molecular activity slams to a halt.

A quantum well carrying a stream of electrons can now take on added elements like transistors. The researchers at UT Arlington created some transistors with just one electron, called single-electron transistors (SETs), attached them to the quantum well, and the SETs worked, thanks to the ultra-cold electrons in the well.

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“These research findings could potentially reduce energy consumption of electronic devices by more than 10 times compared to the present technology,” says Usha Varshney, the program director in the National Science Foundation’s Directorate for Engineering, which funded the research. “Personal electronic devices such as smart phones … can last much longer before recharging.”

Varshney says today’s batteries also can be reduced in size and weight, two of their most significant liabilities. This would make the UT Arlington research valuable not only for consumer devices but also for military applications such as drones, remote sensors and even complex computing in remote locations.

By Andy Tully of Oilprice.com

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