December 9, 2022

Keeping cool with quantum wells

University of Tokyo researchers have announced a new approach for electrical cooling without the need for moving parts. By applying a bias voltage to quantum wells made of the semiconductor aluminum gallium arsenide, electrons can be made to shed some of their heat in a process called “evaporative cooling.”

Quantum wells are nanoscale structures small enough to trap electrons. The type of quantum well used in this research is called an 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 tunneling 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.

Devices based on this principle may be added to electronic circuit boards using conventional semiconductor fabrication methods to help smartphones and laptops avoid performance issues caused by high temperatures. It might also help quantum circuit design and optimization. (University of Tokyo)

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