Nagoya University and NU-Rei Report First Gallium Oxide Thin-Film Epi Growth on Silicon

Why It Matters

By marrying Ga₂O₃’s ultra‑wide bandgap with inexpensive silicon, the technology could slash power‑device costs and overcome thermal limitations, accelerating adoption in electric‑vehicle and aerospace markets.

Key Takeaways

• First Ga2O3 heteroepitaxy on silicon wafers
• New HD-ORS doubles atomic oxygen density for faster growth
• Growth rates exceed 1 µm/h, tenfold MBE improvement
• Silicon substrate reduces cost and improves heat dissipation
• P-type NiO diffusion enables Ga2O3 p‑n junctions

Pulse Analysis

Gallium oxide (Ga₂O₃) has emerged as a leading candidate for next‑generation power semiconductors because of its ultra‑wide bandgap of 4.8 eV, high breakdown field, and ability to operate at temperatures exceeding 500 °C. These attributes make it attractive for electric‑vehicle inverters, high‑efficiency power converters, and radiation‑hard space electronics. However, the material’s commercial rollout has been hampered by the lack of low‑cost, thermally conductive substrates and by slow, temperature‑intensive deposition techniques that limit scalability. The material’s high breakdown field enables devices that can block voltages above 5 kV, a threshold unattainable with silicon carbide.

The Nagoya‑NU‑Rei team solved two of these bottlenecks with a High‑Density Oxygen Radical Source (HD‑ORS) that supplies roughly twice the atomic‑oxygen flux of conventional sources. This richer oxygen environment accelerates the conversion of gallium sub‑oxide to crystalline β‑Ga₂O₃, enabling homoepitaxial growth rates above 1 µm h⁻¹ for both molecular‑beam epitaxy and physical‑vapor deposition. Most notably, the researchers demonstrated the first heteroepitaxial Ga₂O₃ layer on a 2‑inch Si(100) wafer, leveraging a single‑atom gallium seed layer to prevent re‑oxidation and achieve single‑crystal quality.

Integrating Ga₂O₃ with silicon not only slashes substrate costs but also exploits silicon’s superior thermal conductivity, addressing one of the oxide’s key reliability concerns. The same research group also introduced a nickel‑oxide diffusion process that yields p‑type Ga₂O₃, completing the p‑n junction toolkit essential for high‑voltage converters. Together, these advances compress the technology‑to‑market timeline, positioning Ga₂O₃ as a viable alternative to silicon carbide and gallium nitride in power‑dense platforms. Industry players are likely to monitor NU‑Rei’s licensing strategy as the first commercial‑scale production lines could appear within the next two years.