SiC vs GaN

COMPARISON · AI POWER SEMICONDUCTORS

SiC vs GaN for AI power: complementary not competing

Silicon carbide (SiC) and gallium nitride (GaN) are the two wide-bandgap semiconductor materials that matter for AI data centre power. Both offer higher switching frequency, higher efficiency, and higher operating temperature than traditional silicon. But they operate at different voltage classes and different points in the power delivery chain. Choosing between them for a specific application is usually straightforward once the voltage + power + frequency envelope is defined.

01Bottom-line verdict

Complementary. SiC for MV + HV (500V+). GaN for LV switching (<=650V, especially high-frequency). In an AI facility both are typically used: SiC in the solid-state transformer at Layer 2; GaN in Layer 4 rack-level DC-DC conversion; specific silicon-plus-GaN hybrids at Layer 5-6. The two are complementary rather than substitutable, with each mapped to a different voltage class in the stack.

02Comparison table

	SiC (silicon carbide)	GaN (gallium nitride)
Voltage range (practical)	600V to 15kV+	30V to 650V (some pushing higher)
Switching frequency	Up to ~200 kHz typical	Up to ~1 MHz+ typical
Power handling per device	Up to 100s of kW per module	Up to ~10 kW per device
Primary applications in AI	Solid-state transformers (Layer 2); MV-to-LV converters	Rack-level 800V-to-48V (Layer 4); POL adjacent (Layer 6)
Cost trajectory (2026)	Falling from 3-4x Si toward 1.5-2x Si	Falling from 5-8x Si toward 2-3x Si
Supply chain	Wolfspeed + Coherent + STMicro + Rohm; SiC substrate + epi	Navitas + EPC + Infineon + Innoscience (CN); GaN-on-Si epi
Substrate constraint	Concentrated (Wolfspeed + Coherent) but expanding	GaN-on-silicon uses standard Si wafers
Reliability at high temperature	Excellent (>200C junction)	Excellent (>150C junction)
Regulatory + export exposure	BIS export controls do not typically apply	BIS export controls apply to some HEMT products

03Decision framework

Choose SiC (silicon carbide) when

Voltage above 650V. GaN is not commercially available at this voltage class
Solid-state transformer application. SiC is the reference silicon; Amperesand + others use SiC
MV grid interface (utility, EV charging). SiC dominates the MV power electronics market
Long-term reliability under continuous MV stress. SiC has decades of MV field data

Choose GaN (gallium nitride) when

LV switching at high frequency. GaN's frequency advantage compounds efficiency + reduces magnetics size
Rack-level 800V-to-48V conversion. GaN + hybrid GaN/SiC at this voltage class is optimal
Point-of-load + integrated silicon. GaN pairs with silicon POL for direct-to-die architectures (Navitas 800V-to-6V)
Size/weight critical (aerospace, edge). GaN's frequency advantage enables smaller magnetics

04Deep-dive research

Related essays

05Primary sources

Sources consulted

06Frequently asked

Is SiC or GaN more cost-effective for a specific AI power application?

Depends on voltage + frequency envelope. Above 650V: SiC always. Below 200V high-frequency: GaN usually. In the 200-650V range: GaN if frequency matters, SiC if reliability/thermal margin matters.

Why did Wolfspeed restructure if SiC is core to AI power?

Capex-demand timing mismatch. Auto/EV demand softened before AI-power demand ramped. See Wolfspeed retrospective for full analysis.

Is Chinese GaN (Innoscience) competitive?

Yes, and materially cheaper for LV applications. Global availability constrained by US + adjacent export controls; strong domestic + SEA + emerging-market presence.

Where does the 48V bus fit?

48V is the in-rack busbar standard, distinct from the SiC/GaN device question. Both SiC + GaN can be used in DC-DC converters that FEED or CONSUME the 48V bus.

Definition Silicon carbide (SiC) and gallium nitride (GaN) are wide-bandgap semiconductors used in AI data centre power systems. SiC is used in high-voltage stages of 400V to 1200V, covering grid-tie, HVDC and mid-bus conversion. GaN is used in low-voltage high-frequency stages from 12V to 100V, at the point-of-load conversion stage close to the GPU package.

SiC vs GaN in AI power semiconductor comparison
Dimension	SiC (Silicon Carbide)	GaN (Gallium Nitride)
Voltage class (production, 2026)	650V to 1700V (1200V dominant for AI DC)	60V to 650V (100V-200V dominant for point-of-load)
Switching frequency	50 kHz to 500 kHz typical	500 kHz to 5+ MHz typical
Conduction loss vs Si IGBT	30-50% lower at 1200V	40-60% lower at 100V
AI DC application layer	Grid-tie, MV switchgear, 800V bus rectification	48V→1V and 800V→48V point-of-load
Top merchant vendors	STMicroelectronics, Infineon, onsemi, Wolfspeed, ROHM	Navitas, EPC, Innoscience, GaN Systems (Infineon), Power Integrations
Foundry / wafer economics	150mm SiC wafers dominant (200mm ramping 2026-2028)	150mm silicon-substrate GaN (cost-competitive with Si)
Vendor consolidation status	Wolfspeed Chapter 11 restructuring (2026); positioning open	Infineon acquired GaN Systems (Oct 2023, $830M)
2026-2030 growth driver	800V DC data centre + EV + industrial	800V DC data centre point-of-load + consumer fast-charging