In 2011, the world held its breath as the Fukushima Daiichi nuclear plant in Japan went into failure with its cooling systems — just a day after the country was hit by a 9.0-magnitude earthquake and tsunami. The worry was justified: the meltdown that followed — during which highly radioactive material spread in all directions — became one of the worst nuclear-related disasters ever.

More than a decade later, the cleanup is still under way. Last month, the Japanese government launched a testing process to clear out radioactive debris in and around the plant - a major step in the decommissioning process of the plant, which is expected to complete its process by 2051.

An interesting participant in that process is Ookuma Diamond Device (ODD), a remarkable Japanese startup-a second, using diamond chips to clean up radioactive debris; a third, powering amplifiers with diamond chips. It has just raised 4 billion yen, or about $27 million, to construct the world's first diamond semiconductor manufacturing facility in the town of Ookuma, a little out of Fukushima.

ODD's plans are to construct the factory in January 2025 and have it operational by Summer 2026.

Why use diamond chips rather than traditional silicon-based semiconductors?

Diamond is known as a WBG semiconductor material — other examples include SiC (silicon carbide) and GaN (gallium nitride). WBG materials are thought to have superior power conversion efficiency and extraordinary thermal management.

Unfeatured silicon-based CPUs, GPUs, and NPUs, the diamond-based chip doesn't have circuitry. Diamond semiconductors act more like potent control devices rather than tiny sources of electricity, Coral Capital partner Ken Nishimura said TechCrunch. According to him, the semiconductor made of diamond will be used in bigger buildings, such as those of nuclear power plants that need super high temperatures and radiation levels that silicon-based chips cannot support.

The National Institute of Advanced Industrial Science and Technology and Hokkaido University facilities have produced successful prototyped diamond semiconductor amplifiers which can work under 300°C.

Fundamentally, diamond semiconductors we create differ from traditional silicon-based chips because of the superior material properties, said Yuhei Nagai, CFO, Ookuma Diamond Device in an exclusive interview with TechCrunch. Compared to other advanced semiconductors like SiC and GaN, the power conversion efficiency of diamond semiconductors is superior, while next-generation technologies such as 6G, space, defense, and nuclear get superior thermal management.

Of course, noteworthy is the fact that diamond chips can be produced from methane gas, which in itself could make full production possible in Japan. This is in contrast to GaN, wherein sourcing materials is highly controlled by China.

Odds are rather working on "pure diamond semiconductors" than making GaN semiconductors on a diamond substrate, as said by Nagai. Diamond materials for chips is still projected to reach $10 billion by 2032, and from what we know as of 2023, that figure is $113.7 million. This was according to a recent report.

This is a startup that spun out from Japan's National Institute of Advanced Industrial Science and Technology, or AIST, and Hokkaido University, formed particularly in 2021 to assist the decommissioning process at Fukushima Daiichi Nuclear Power Plant.

Two co-founders, Dr. Junichi Kaneko and Dr. Hitoshi Umezawa, have researched diamond chips for more than 20 years. Once the disaster occurred, the work they were doing was thrown into public attention, more resources for R&D, and eventually, the startup was founded. In 2021, ODD constructed the very first practical diamond chip in the world.

The jumps, however between theory, chip, and actual product are still huge. Two founders also lead the much broader national project of the Japanese government, that makes an actual product which has the potential to extract radioactive debris from natural disasters.

"The [ODD's] prototypes represent a world-first achievement—no one else has been able to develop functioning diamond semiconductor amplifiers to this point," said Nagai.

Some global companies are even also working on diamond semiconductors, such as Diamfab of France, Element Six of U.K., and A.L.M.T. in Japan, a subsidiary of Sumitomo Electric Industries.
ODD is singular because it boasts of being the only company with end-to-end know-how from substrate to packaging, which enables this world's prototype of a diamond semiconductor amplifier.

This week, the company is also in discussions with more than 10 potential customers globally in the nuclear power plant, aerospace, and telco industries, said Nagai. The area was given more attention after it was found this week that Google inked a deal to collaborate on powering data centers using nuclear power.

The company raised the funding led by Globis Capital, bringing its total raised to about $45 million (6.7 billion yen) since inception with participation from Coral Capital, aSTART, Green Co-Investment Investment, Japan Post Bank Spiral Regional Innovation Fund, Mitsui Sumitomo Insurance venture capital, SMBC Venture Capital and among others.

It has also received around $15 million in government grants from the Cabinet Office, METI, MIC, ATLA, and the Reconstruction Agency. Presently it employs 27 people.