Roughly a tenth of the world's electricity is lost as heat during power conversion. Gallium oxide is one of the materials being lined up to shrink that number.

In December 2025, FLOSFIA, a Kyoto University spinoff, said it had completed verification of the manufacturing process for 4-inch wafers, the step that makes volume production possible. By the company's account, substrate costs run up to 50 times lower than SiC, and crystal growth equipment costs less than a tenth as much.

What Is Gallium Oxide? The "Ultimate Material" for Power Semiconductors

Power semiconductors are essential components that convert and control electrical power. While silicon (Si) has dominated for decades, next-generation materials like silicon carbide (SiC) and gallium nitride (GaN) are gaining traction.

Gallium oxide (Ga2O3) sits beyond both. Material suitability is measured by the Baliga figure of merit. Set silicon at 1: SiC scores around 500, GaN around 930. Gallium oxide varies by crystal structure, with the beta form at 3,444 and the alpha form, the corundum structure FLOSFIA works with, at 6,726. The company describes its alpha material as roughly 7,000 times silicon and about 20 times SiC.

There is a catch. Gallium oxide conducts heat an order of magnitude worse than Si, SiC or GaN, so heat generated in operation is harder to move out. Thermal design is a precondition, not an afterthought.

FLOSFIA's Technical Breakthrough

On December 24, 2025, FLOSFIA announced it had completed verification of manufacturing technology for 4-inch α-Ga2O3 wafers, hitting the target it had set out a year earlier of finishing during 2025.

The reliability problem that had dogged its Schottky barrier diodes (SBDs) also moved toward resolution. The company had been dealing with inconsistent reliability traced to surface processing of α-Ga2O3; it narrowed the cause to two factors, microscopic surface roughness and a particular class of crystal defect, and built detection methods for each.

Measured results:

  • 600V breakdown voltage, 10A-class devices successfully prototyped
  • Leakage current under reverse voltage reduced to less than 1/1000th of previous levels
  • Devices survived 1,500 hours of continuous reverse bias testing at 150°C

Three Reasons for the Dramatic Cost Advantage

What draws attention to FLOSFIA's approach is cost before performance.

1. Sapphire Substrate Utilization

Substrates account for 48% of SiC device manufacturing cost. α-Ga2O3 devices grow their crystal on sapphire, which is widely available and cheap, cutting substrate cost by up to a factor of 50. Sapphire wafers trade at roughly a tenth to a fiftieth the price of same-size SiC.

2. Proprietary "Mist Dry Method"

FLOSFIA uses Mist Dry, its own development of the Mist CVD technique created at Kyoto University. Raw materials are atomized and sprayed onto a heated substrate, where the crystal grows. Because no vacuum system is required, equipment investment comes in below a tenth of the MOCVD and HVPE crystal growth systems used for SiC.

3. Existing Factory Compatibility

Process equipment already installed in GaN-LED and SiC fabs can be reused, which lowers the bar for stepping into volume production.

Applications and Market Outlook

The target applications sit wherever high voltage and high current meet: EV power control units, data center power supplies, solar inverters, industrial robot drives. In EVs, where range and charging time are the live constraints, lower conversion loss translates directly.

Yano Research Institute puts the global market for wide-bandgap semiconductor single crystals, on a manufacturer shipment basis, at 286.9 billion yen in 2025 and 829.8 billion yen in 2035. Power semiconductors for battery EVs, rolling stock and industrial equipment are expected to drive that growth.

Implications for Japan's Semiconductor Industry

The SiC market currently faces intense price competition due to slowing EV demand and massive investment by Chinese manufacturers. Japanese companies maintain technological advantages but struggle with cost competitiveness.

FLOSFIA has filed more than 700 patents around α-Ga2O3, making the material technology itself the barrier to entry.

Its shareholders include DENSO, Mitsubishi Heavy Industries, Daikin Industries, Yaskawa Electric and JSR. Joint development runs with DENSO on automotive applications and with Mitsubishi Heavy on industrial equipment.

Future Prospects and Challenges

FLOSFIA plans to extend breakdown voltage from 600V to 1,200V and 1,700V, with current ratings rising from 10A into the hundreds. In its December 2025 announcement, the company said it would accelerate work on production technology for MOSFETs, which account for more than 70% of the power device market, and for JBS diodes. Yield and process knowledge earned on SBDs carries over to both.

The technical obstacles have not gone away. Gallium oxide resists P-type layer formation, which narrows the range of workable device structures. FLOSFIA developed a P-type material, iridium gallium oxide (α-(IrGa)2O3), to attack that constraint, but establishing it at production scale is still ahead.

Context worth keeping: in December 2024 the company announced it was revising the SBD mass production start it had originally set for 2024, saying it needed more time to clear reliability testing. The verification just completed is the recovery from that pause.

Japan is betting on gallium oxide as the post-SiC material. How far along is next-generation power semiconductor development where you are?

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