Nagoya Uni team grows Ga₂O₃ on silicon
Researchers at Nagoya University in Japan, in collaboration with university spinout NU-Rei, are presenting six advances in the growth of Ga₂O₃.
The results are being presented at the spring meeting of the Japan Society of Applied Physics (March 15-18, 2026) by a research group from Nagoya University's Centre for Low-temperature Plasma Sciences.
Together, the six results advance the full process stack needed to bring Ga₂O₃ devices closer to manufacturing, and include a world-first heteroepitaxial growth—growing a crystalline layer of Ga₂O₃ on a structurally different substrate — on silicon wafers, a step that could significantly reduce device cost and improve heat dissipation, accorrding to the team.
These results build on a related advance in Ga₂O₃ p-type control reported by Nagoya University in September 2025, and are being commercialised through the company NU-Rei, with the goal of supporting industrial adoption of Ga₂O₃ growth processes for high-voltage, high-frequency, and silicon-integrated device applications.
Central to the work is a newly developed High-Density Oxygen Radical Source (HD-ORS), which doubles the density of atomic oxygen available during thin-film growth compared to conventional sources.
The higher oxygen density strongly promotes the chemical reaction needed to convert gallium suboxide into the desired Ga₂O₃, while suppressing the volatile by-product that would otherwise escape the surface and limit how fast the film can grow. The source is compatible with both MBE and PVD.
Advances across the full process stack
HD-ORS development The new oxygen source uses an ozone-oxygen mixed gas to double atomic oxygen density, making it compatible with both MBE and PVD and establishing a high-efficiency foundation for all subsequent growth work.
High-speed MBE homoepitaxial growth Using HD-ORS, the team achieves homoepitaxial growth of β-Ga₂O₃ on tin-doped Ga₂O₃ substrates at 300°C and a rate of 1µm per hour. Growth on the (001) plane was confirmed using X-ray diffraction (XRD) and reflection high energy diffraction (RHEED). The low growth temperature reduces thermal stress and broadens compatibility with other device components.
High-speed PVD homoepitaxial growth Applying HD-ORS to PVD achieves stable (001)-oriented homoepitaxial films at rates exceeding 1 µm per hour, approaching ten times the rate of conventional MBE and pointing toward industrial-scale production.
Silicon substrate preitreatment For growth on silicon, the team establishes a pretreatment combining wet chemical cleaning with controlled adsorption of a single atomic layer of gallium onto the silicon surface. This prevents re-oxidation during heating and proves essential for subsequent heteroepitaxial growth.
World-first heteroepitaxial growth on silicon The team achieves heteroepitaxial growth of Ga₂O₃ on two-inch Si(100) wafers, with heat treatment confirming single-crystal formation. Silicon substrates are far less expensive than native Ga₂O₃ substrates, and silicon's superior thermal conductivity addresses one of gallium oxide's known material limitations.
p-type formation via NiO diffusion layers Gallium-based semiconductors are difficult to dope into p-type form, which is required to build the pn junctions at the heart of power devices. Using nickel ion implantation followed by annealing, the team forms a graded nickel oxide (NiO) diffusion layer with p-type characteristics, confirming pn-junction behaviour on both Ga₂O₃ and GaN substrates, with twice the current density of a standard nickel Schottky diode.
