Unlocking Ultra-High Voltage Capabilities for Next-Generation Power Electronics

Gallium oxide (Ga₂O₃) power devices outperform traditional silicon (Si) and even silicon carbide (SiC) power devices in terms of breakdown voltage, specific on-resistance, and material availability-critical for ultra-high voltage (UHV) power conversion applications. According to the IEEE Power Electronics Society 2025 Technical Report, Ga₂O₃ exhibits an ultra-wide bandgap of 4.9 eV, which is 1.7 times wider than SiC (3.2 eV) and 3.5 times wider than Si (1.1 eV). This enables Ga₂O₃ devices to achieve a breakdown electric field of 8 MV/cm, surpassing SiC (3 MV/cm) and Si (0.3 MV/cm) by significant margins. Additionally, Ga₂O₃-based Schottky barrier diodes (SBDs) demonstrate a specific on-resistance (Rₒₙ,ₛₚₑᶜ) of 0.5 mΩ·cm² at 2 kV, which is 60% lower than SiC SBDs (1.25 mΩ·cm²) and two orders of magnitude lower than Si-based IGBTs (50 mΩ·cm²), enabling higher power density and lower conduction losses.

A Japanese research team announced a major breakthrough in Ga₂O₃ single-crystal growth in Q1 2026, published in Applied Physics Letters. By optimizing the edge-defined film-fed growth (EFG) process with a high-purity Ga₂O₃ source (99.9999%), the team successfully fabricated 6-inch β-Ga₂O₃ single-crystal substrates with a defect density of 2×10⁴ cm⁻²-75% lower than conventional 4-inch substrates (8×10⁴ cm⁻²). This improvement significantly enhances the device's reliability, with the resulting Ga₂O₃ MOSFETs exhibiting a breakdown voltage of 5 kV and a lifetime of 5,000 hours under continuous operation, a 300% improvement over previous generations.

Meanwhile, a U.S.-based semiconductor firm developed a novel recessed-gate structure for Ga₂O₃ MOSFETs. By integrating a high-κ HfO₂ dielectric layer via atomic layer deposition (ALD) and optimizing the gate recess depth to 150 nm, the company achieved a threshold voltage of 3.2 V and a transconductance of 25 mS/mm-performance metrics that surpass planar-gate Ga₂O₃ MOSFETs by 45%. The recessed-gate structure also reduces gate leakage current to 1×10⁻¹² A/mm, meeting the stringent requirements for UHV power electronics. According to the 2026 International Symposium on Power Semiconductor Devices and ICs (ISPSD) Technical Report, the fabricated Ga₂O₃ MOSFETs achieve an efficiency of 99.6% in a 3 kV power conversion system, outperforming SiC-based systems (99.2%).

In the ultra-high voltage power grid sector, Ga₂O₃ power devices are being explored for 500 kV and above AC/DC conversion systems. A Chinese power equipment manufacturer developed a Ga₂O₃-based 500 kV rectifier module, which reduces the module volume by 40% and power loss by 25% compared to SiC-based modules. This enables more compact and efficient power grid infrastructure, critical for integrating large-scale renewable energy sources (e.g., wind, solar) into the grid. For electric vehicles (EVs) with 1200 V high-voltage platforms, a South Korean automaker integrated Ga₂O₃ SBDs into the on-board charger (OBC), reducing the OBC size by 35% and improving charging efficiency from 96% to 98.5%, enabling faster charging and extended driving range.

In the aerospace industry, Ga₂O₃ devices' high voltage capability and lightweight properties make them ideal for satellite power systems. A European aerospace firm integrated Ga₂O₃ power modules into a geostationary satellite, reducing the power system weight by 30% and improving energy conversion efficiency by 18% compared to traditional Si-based systems. Additionally, in industrial power supplies (e.g., 10 kV DC power supplies for semiconductor manufacturing), Ga₂O₃ devices enable a power density of 10 kW/L-double that of SiC-based power supplies (5 kW/L)-significantly reducing equipment footprint and energy consumption.

The commercialization of Ga₂O₃ power devices is hindered by three core challenges: material defect density, low carrier mobility, and limited large-scale fabrication capability. Despite recent breakthroughs, the carrier mobility of Ga₂O₃ (200 cm²/V·s for electrons) is still lower than SiC (1000 cm²/V·s) and Si (1400 cm²/V·s), limiting the switching speed of high-power devices. High defect density in large-area substrates also leads to inconsistent device performance, with a uniformity error of 12% across 6-inch wafers-higher than the industry target of 5%.

Market-wise, global Ga₂O₃ power device production is in the early R&D to pilot production stage, accounting for less than 1% of the global power semiconductor market in Q1 2026. Major manufacturers such as Panasonic, Fujitsu, and Northrop Grumman are investing heavily in scaling up production, but mass commercialization is expected to start in 2030. Supply chain constraints also exist-high-purity Ga₂O₃ raw materials and specialized EFG growth equipment are dominated by a few Japanese and U.S. suppliers, leading to a 18-week delivery cycle and a 50% cost premium compared to SiC devices. Additionally, there is a lack of unified international standards for Ga₂O₃ device performance testing (e.g., breakdown voltage, long-term reliability), which hinders market acceptance and cross-industry collaboration.