Sandwich-Style Semiconductors Powered by Exciton-Polaritons Could Dramatically Boost Efficiency

Designed to replace existing electronics with "excitronics," the novel technique creates a device that doesn't waste any energy as heat.

Gareth Halfacree
11 days agoHW101

A team of scientists have come up with a new "sandwich-style" construction technique for semiconductors that, they say, could lead to a future of ultra-low-power electronics which run on exciton-polaritons.

Exciton-polaritons are a hybrid of light and matter, and unlike electrons are capable of flowing in a semiconductor without loss of energy — in principle, at least. The only difficulty: Coming up with an ultra-thin semiconductor in which they could flow — which is where the research project comes in.

The team was able to create an atomically-thin material capable of coupling excitons at room temperature — and proved that long-distance propagation without energy loss is possible, thanks to a clever sandwich-style construction technique which traps a single-atom-thick semiconductor layer between two mirrors to create an optical microcavity.

“The choice of the atomically-thin material in which the excitons travel is far less important [than its construction]. We found that construction of that microcavity was the key," explains lead author Matthias Wurdack, "And while we used tungsten sulfide (WS2) in this particular experiment, we believe any other atomically-thin TMDC material would also work."

The creation of the microcavity, however, owes much to an accident which created an air gap between the two mirrors, knocking them out of alignment. That slope, a failure in the fabrication process, turned out to be key to allowing the device to conserve energy — and could be how future electronics boost their efficiency while generating zero waste heat.

"This demonstration, for the first time, of ballistic transport of room-temperature polaritons in atomically-thin TMDCs [Transition Metal Dichalcogenides] is a significant step towards future, ultra-low energy exciton-based electronics," claims Elena Ostrovskaya, professor at the Australian National University, of the work.

The team's work has been published under open-access terms in the journal Nature Communications, but there has not yet been a public announcement of a roadmap to commercialization.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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