The third-generation semiconductor revolution is being driven by silicon carbide (SiC), a wide-bandgap material prized for its ability to operate at high voltages, high frequencies, and elevated temperatures. Among the different categories of SiC substrates, two stand out:

4H-N SiC – the backbone of today’s power electronics.

Semi-insulating (SI) SiC – the enabler for high-frequency RF and microwave applications.

Both are now available in 6-inch wafer sizes, signaling industrial maturity. But as the market evolves, a question emerges: Will demand for 6-inch semi-insulating SiC eventually surpass that of 4H-N SiC?

4H-N SiC: Powering the EV and Energy Era

4H-N SiC substrates are doped with nitrogen, resulting in low resistivity and high conductivity. They are the essential building block for:

SiC MOSFETs – widely adopted in electric vehicle inverters, boosting efficiency and extending driving range.

Schottky barrier diodes (SBDs) – improving power density in fast chargers and solar inverters.

IGBTs and power modules – enabling compact, reliable, and energy-efficient industrial drives.

Market drivers:

EV boom: Each EV requires dozens of SiC chips for its traction inverter, OBC, and DC/DC converters. Analysts estimate the SiC device market for EVs will exceed $10B by 2030.

Green energy: Solar and wind systems increasingly rely on SiC inverters to improve grid efficiency.

Industrial adoption: Robotics, data centers, and smart factories are migrating to SiC-based power modules.

With multiple global manufacturers (Wolfspeed, Rohm, Infineon, STMicroelectronics, and Chinese players) expanding 6-inch SiC capacity aggressively, conductive 4H-N substrates currently account for the largest share of SiC wafer demand worldwide.

Semi-Insulating SiC: The Future of RF and Beyond

Semi-insulating (SI) SiC wafers are engineered to have extremely high resistivity (typically >10⁹ Ω·cm). This makes them an ideal platform for GaN-on-SiC epitaxy, where high-power RF and microwave devices are fabricated.

Key applications：

5G base stations: Power amplifiers built on GaN-on-SiC can handle higher frequencies and reduce power loss.

Satellite communications: Constellations of LEO satellites require compact, reliable RF components with high thermal conductivity—an area where SI SiC excels.

Defense and radar: X-band and Ka-band radar systems leverage SI SiC substrates for high output power and signal fidelity.

Emerging 6G networks: With frequencies pushing toward terahertz, SI SiC is expected to be a foundational material.

Market drivers:

The rollout of 5G infrastructure, with more than 100 countries deploying or planning networks.

Satellite internet projects (e.g., Starlink, OneWeb, and China’s “GW” constellation), which demand thousands of RF front-end modules.

Growing defense budgets worldwide, particularly in advanced radar and electronic warfare.

Although SI SiC represents a smaller market today, its compound annual growth rate (CAGR) is projected to be higher than conductive SiC, thanks to 5G and aerospace momentum.

Manufacturing & Technical Challenges

Conductive 4H-N SiC: Production of 6-inch wafers has become relatively mature, with yields improving and defect density decreasing. Costs are falling as more fabs scale up.

Semi-insulating SiC: More difficult to manufacture. Maintaining high resistivity while minimizing defects (such as micropipes and basal plane dislocations) requires precise control of compensation doping. Costs remain higher, and large-volume supply is still limited.

Will SI SiC Overtake 4H-N SiC?

Looking at both the technical and market perspectives:

Short to Medium Term (3–5 years)

Conductive 4H-N SiC will dominate by volume, driven by the EV and renewable energy megatrends.

SI SiC demand will grow but remain smaller, concentrated in telecom, satellite, and defense.

Long Term (5–10 years)

SI SiC will become increasingly strategic, especially with 6G networks, massive satellite constellations, and advanced radar.

However, given the massive scale of the automotive and energy sectors, 4H-N SiC is unlikely to be surpassed in overall demand.

Conclusion

The real answer is not about one technology replacing the other—it’s about complementary growth.

4H-N SiC will continue to be the growth engine for mass-market power electronics.

Semi-insulating SiC will expand as a high-value enabler for RF, aerospace, and next-generation communication.

Rather than a competition, the two substrates represent parallel tracks, each powering critical industries of the future.

In other words:

Conductive SiC fuels the electric age.

Semi-insulating SiC fuels the connected age.

Both are indispensable pillars in shaping the semiconductor landscape of the next decade.