Japanese boffins slice semiconductors from diamonds – with lasers!

Scientists at Japan's Chiba University claim they've developed a method that uses lasers to create diamond wafers that could one day power next-gen semiconductors.

Silicon remains the prime material for semiconductors, but diamonds are attractive because carbon in diamond form has a rather wide bandgap.

A wide bandgap allows semiconductors to function more efficiently at higher voltages, frequencies, and temperatures than is possible using silicon alone. The desirability of a wide bandgap is one of the reasons that Silicon Carbide (SiC) components have become such a hot commodity as electric vehicle adoption has accelerated.

Diamond has an even wider bandgap than SiC. That's great news if you want to build ultra-efficient power circuitry. The bad news is, diamonds are rather brittle and hard to work with.

That may seem counterintuitive – there's a reason they say "diamonds are forever." They're famously hard. But it's that very hardness that makes them tricky – when they crack, they crack in very particular ways. And those ways aren't ideal for making semiconductor wafers.

Because of this, diamond wafers have had to be synthesized – a process that's prohibitively expensive compared to working with alternative materials, as the researchers explained in a recent blog post.

Hirofumi Hidai, a professor at the Chiba University School of Engineering, and associates have been exploring ways to get around this using lasers to influence the way a diamond cracks along a chosen plane. Their work was detailed in an article published in the journal Diamond & Related Materials.

"Diamond slicing enables the production of high-quality wafers at low cost and is indispensable to fabricate semiconductor devices," Hidai explained in a statement. "This research brings us closer to realizing diamond semiconductors for various applications in our society such as improving the power conversion ratio in electric vehicles and trains."

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According to Hidai, the process involves using laser light to transform regions of the diamond into amorphous carbon, which has a lower density than the rest of the diamond and is less inclined to crack.

Controlling the formation of cracks through the diamond, so that they form along the desired plane, is key to creating a viable wafer. To do this, the researchers used the laser to create a grid-like pattern of crack-prone regions. These regions help to guide the propagation of cracks along the desired path. To remove the slice — or wafer, if you prefer — a tungsten needle is against the side of the diamond until it breaks free.

Hidai and the University of Chiba are far from the only ones looking to harness diamond's dense lattice of carbon atoms to power next-gen computing and communications technologies.

In April, Amazon Web Services teamed up with De Beers subsidiary Element Six to develop synthetic diamonds for use in quantum key distribution. The idea there is to engineer defects into the diamond – called color centers – which can absorb photons containing quantum information, then re-emit them. Amazon hopes to harness this phenomenon to create repeaters capable of extending the reach of quantum key distribution to its global network.

In an earlier interview, Antia Lamas-Linares, who leads the AWS Center for Quantum Networking, told The Register that quantum networks were just a handful of years away. ®