New way to cool micro-electronic devices

May 18, 2015 by Bob Yirka, Phys.org report

New way to cool micro-electronic devices
Credit: Yoan Léger/Institut national des sciences appliquées de Rennes
(Phys.org)—A team of researchers working at the University of Grenoble has developed a new way to cool solids at the micro level. In their paper published in Physical Review Letters, the team describes how they used laser light to remove vibrational heat from a semiconductor material.

Scientists have known for some time that it is possible to cool a solid by shooting it with a laser beam, a technique known as anti-Stokes fluorescence (ASF)—the creates an electron-hole pair, aka an exciton, which in turn absorbs thermal energy, aka phonons. When the exciton decays, it forms into a photon, which escapes as light. One problem with this approach has been a tendency for some excitons to decay in a way that allows the heat to return to the material. In this new effort, the researchers found a way around this problem.

The new approach involves the use of polaritons instead of excitons—polaritons are formed when photons interact with excitons. To make use of polaritons, the researchers had to force them to be confined in a semiconducting sandwich cavity (partially transparent mirrors keep them from escaping) preventing them from decaying via just phonons. The result is a method for using a light beam to cool very tiny solid materials, such as those perhaps, that are used in electronic devices.

The researchers note that in addition to being an improvement over conventional ASF schemes, their technique should work the same way at extremely low temperatures, (because the polaritons interact with phonons and polaritons allowing for absorption of phonons over a large range of energies.)

The team acknowledges that their technique has a long way to go before it could be used to create actual device coolers, but insist that in the end it should work, and further suggest when that occurs, the polaritons could offer their cooling in two different ways, fast, or slow. The fast approach would allow for quicker cooling, but would result in more heat being returned to the material. The slow approach on the other hand would take longer but would be more efficient. The team plans to next build a "polariton refrigerator" that should be able to actually cool very small objects.

Explore further: Researchers take a step towards development of optical single-phonon detector

More information: Exciton-Polariton Gas as a Nonequilibrium Coolant, Phys. Rev. Lett. 114, 186403 – Published 5 May 2015. dx.doi.org/10.1103/PhysRevLett.114.186403 . On Arxiv: arxiv.org/abs/1412.2630

ABSTRACT
Using angle-resolved Raman spectroscopy, we show that a resonantly excited ground-state exciton-polariton fluid behaves like a nonequilibrium coolant for its host solid-state semiconductor microcavity. With this optical technique, we obtain a detailed measurement of the thermal fluxes generated by the pumped polaritons. We thus find a maximum cooling power for a cryostat temperature of 50 K and below where optical cooling is usually suppressed, and we identify the participation of an ultrafast cooling mechanism. We also show that the nonequilibrium character of polaritons constitutes an unexpected resource: each scattering event can remove more heat from the solid than would be normally allowed using a thermal fluid with normal internal equilibration.

Related Stories

Spiral laser beam creates quantum whirlpool

November 17, 2014

(Phys.org) —Physicists at Australian National University have engineered a spiral laser beam and used it to create a whirlpool of hybrid light-matter particles called polaritons.

Researchers demonstrate laser cooling of a semiconductor

January 28, 2013

(Phys.org)—A team of physicists working in Singapore has, for the first time, demonstrated the cooling of a semiconductor using a laser. To achieve this feat, the team, as they describe in their paper published in the journal ...

The power of light-matter coupling

February 5, 2015

A theoretical study shows that strong ties between light and organic matter at the nanoscale open the door to modifying these coupled systems' optical, electronic or chemical properties.

Recommended for you

Engineers invent groundbreaking spin-based memory device

December 7, 2018

A team of international researchers led by engineers from the National University of Singapore (NUS) have invented a new magnetic device to manipulate digital information 20 times more efficiently and with 10 times more stability ...

Multichannel vectorial holographic display and encryption

December 7, 2018

Holography is a powerful tool that can reconstruct wavefronts of light and combine the fundamental wave properties of amplitude, phase, polarization, wave vector and frequency. Smart multiplexing techniques (multiple signal ...

A new 'spin' on kagome lattices

December 7, 2018

Like so many targets of scientific inquiry, the class of material referred to as the kagome magnet has proven to be a source of both frustration and amazement. Further revealing the quantum properties of the kagome magnet ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.