Quantum wells could keep electronics cool

October 03, 2019 //By Peter Clarke
Quantum wells could keep electronics cool
Researchers at the Univeristy of Tokyo have demonstrated how a new approach to the cooling of electronic substrates can be achieved by moving electrons through compound semiconductor quantum wells.

The work, reported in Nature Communications , has shown quantum well cooling effects of up 50 degrees centigrade.

It operates by applying a bias voltage to quantum wells made of the semiconductor aluminium-gallium-arsenide (AlGaAs). Electrons trapped in the quantum well can be made to shed some of their heat in a process called "evaporative cooling." Devices that exploit this principle could in theory be added to circuit boards, and integrated circuits using conventional semiconductor manufacturing processes to cool dense products that are prone to high temperatures – such as smartphones and laptop computers.

The technology is akin to the already well-understood thermionic cooling but is novel phenomenon that exploits the nanoscale structure of an electron-trapping quantum well known as the asymmetric double-barrier heterostructure.

In these devices, very narrow gallium arsenide wells are separated by layers of aluminum gallium arsenide. When the applied bias voltage is equal to energy of the quantum level inside the well, electrons can use resonant tunnelling to easily pass through a barrier. However, only the electrons with high kinetic energies will be able to continue past a second barrier. Since the "hotter" fast-moving electrons escape, while the "cooler" slow electrons become trapped, the device becomes colder.

This "evaporative cooling" is analogous to the process that makes you feel cold when you step out of a swimming pool. The water molecules with the most thermal energy are the first to evaporate off your skin, taking their heat with them.

"We have achieved electron cooling of up to 50 degrees centigrade under ambient conditions. These results make our quantum well devices promising for comprehensive heat management in smart devices," said senior author Kazuhiko Hirakawa, in a statement.

"Future smartphones may come with internal circuit boards packed with even more components, as long as they also have some of these cooling quantum wells."

Related links and articles:

www.u-tokyo.ac.jp

Nature Communications paper "Evaporative electron cooling in asymmetric double barrier


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