Silicon Carbide and Gallium Nitride Power Semiconductors
Silicon has been the default material for power electronics for over 50 years. IGBTs and MOSFETs built on silicon handle everything from motor drives to power supplies to grid infrastructure. But silicon is approaching its theoretical limits for power conversion, and two wide-bandgap materials — silicon carbide (SiC) and gallium nitride (GaN) — are taking over applications where efficiency, size, and thermal performance matter. I've been following this transition closely, and it's one of the most consequential shifts in the semiconductor industry right now.
The Physics Behind the Hype
The key difference is the bandgap — the energy required to move an electron from the valence band to the conduction band. Silicon's bandgap is 1.1 eV. Silicon carbide (specifically the 4H polytype used in power devices) is 3.26 eV. Gallium nitride is 3.4 eV. This matters because a wider bandgap means:
- Higher breakdown voltage per unit thickness — a SiC device can block 10x the voltage of a silicon device with the same drift region thickness
- Higher operating temperature — SiC devices can function at 200+ C junction temperatures where silicon would fail
- Lower on-resistance at the same voltage rating — this translates directly to lower conduction losses
- Faster switching — smaller devices with less charge storage means less energy wasted during switching transitions
In concrete terms, replacing a 1200V silicon IGBT with a 1200V SiC MOSFET in a motor drive can improve system efficiency by 2-5 percentage points. That sounds small, but for an EV drivetrain consuming 100 kW, it means 2-5 kW less heat to dissipate, which means a smaller cooling system, and more range per charge.
Silicon Carbide: The EV Revolution
SiC's biggest market driver is electric vehicles. Tesla was the first major automaker to adopt SiC MOSFETs, using STMicroelectronics' devices in the Model 3 traction inverter starting in 2018. This was a watershed moment — it proved that SiC could meet automotive reliability requirements at volume.
Today, SiC traction inverters are used by BYD, Hyundai, Lucid, Rivian, Mercedes, BMW, and many others. The key suppliers of SiC power devices include:
We covered a related topic in Yield Engineering: Why Chip Manufacturing Yield Matters More.
- STMicroelectronics — the largest SiC revenue generator, supplying Tesla and many other OEMs. They manufacture on 200mm (8-inch) SiC wafers at their Catania, Italy fab.
- Wolfspeed (formerly Cree's Wolfspeed division) — the largest SiC substrate manufacturer and a major device supplier. They're building the world's largest SiC fab in Siler City, North Carolina, targeting 200mm wafer production.
- Infineon — acquired Siltectra for laser-based SiC wafer splitting technology, reducing material waste. Their CoolSiC MOSFET family is widely used in industrial applications.
- onsemi — supplies SiC to major EV OEMs and has made big investments in vertical integration, from substrate growth to device fabrication.
- Rohm Semiconductor — a Japanese SiC pioneer, supplying devices for automotive and industrial customers.
The SiC supply chain has a unique bottleneck: substrate manufacturing. Growing SiC crystals is incredibly difficult. The material grows at about 0.3 mm per hour (compared to 30+ mm/hour for silicon crystal growth), and defect densities are much higher. A single 150mm SiC substrate costs $500-1,000, compared to $10-20 for a silicon wafer. The transition to 200mm wafers is happening now, which should improve cost per die by 40-60%, but it's a challenging process.
Gallium Nitride: Speed and Density
GaN power devices target a different sweet spot than SiC. While SiC dominates at high voltages (900V-3300V) and high power (kilowatts to megawatts), GaN excels at lower voltages (100V-650V) where switching speed matters most.
The most common GaN power device is the HEMT (High Electron Mobility Transistor), which uses a two-dimensional electron gas (2DEG) at the interface between GaN and aluminum gallium nitride (AlGaN). This 2DEG has extremely high electron mobility, enabling fast switching with very low on-resistance.
Here's what makes GaN compelling for power conversion:
For a related perspective, see ASML and the EUV Monopoly: Why One Company Controls Advanced.
- Switching frequencies of 1-10 MHz are practical, compared to 50-200 kHz typical for silicon MOSFETs. Higher frequency means smaller inductors and capacitors, which shrinks the power supply dramatically.
- Zero reverse recovery charge — GaN HEMTs don't have a body diode with stored charge, eliminating a significant loss mechanism in switching converters.
- GaN-on-silicon epitaxy — unlike SiC, which needs expensive SiC substrates, GaN power devices are grown on standard silicon wafers (typically 200mm), making them compatible with existing fab infrastructure.
The GaN power market is led by a few key players:
- GaN Systems (acquired by Infineon in 2023) — pioneered high-current GaN transistors for automotive and industrial use
- EPC (Efficient Power Conversion) — led by Alex Lidow, a veteran of the power semiconductor industry. EPC makes enhancement-mode GaN FETs on silicon substrates. Their parts dominate the high-frequency, low-to-mid power market.
- Texas Instruments — integrates GaN transistors into complete power IC solutions (driver + GaN switch in one package), which dramatically simplifies design. Their LMG341x family is popular for server power supplies.
- Navitas Semiconductor — developed GaNFast ICs that integrate GaN power transistors with GaN logic and driver circuits on a single chip. They've shipped over 200 million units, mostly in fast chargers for phones and laptops.
- Power Integrations — integrates GaN switches into their PowiGaN product line for AC-DC adapters.
Where Each Technology Fits
I find it useful to think about the application space in terms of voltage and power:
At 30-100V: Silicon MOSFETs are still king for most applications, but GaN is competitive for very high frequency converters (48V data center power, lidar drivers, Class-D audio).
At 100-650V: GaN is taking share rapidly. USB-C fast chargers are almost universally GaN now — Apple, Samsung, Anker, and others all use GaN transistors in their adapters. The typical 65W GaN charger is less than half the size and weight of an equivalent silicon design. Server and telecom power supplies are transitioning to GaN for similar reasons.
See also: Chip Ô Tô Tự Lái 2026: Tesla vs Qualcomm vs Mobileye.
At 650-1700V: SiC dominates. EV traction inverters (typically 400V or 800V bus), solar inverters, EV charging stations, and industrial motor drives are the primary applications.
At 1700V-3300V+: SiC is starting to replace silicon IGBTs in traction (trains, metros), medium-voltage drives, and grid applications. This is still early but growing fast.
Cost Trajectories and Adoption
The cost premium for wide-bandgap devices is shrinking but still significant. A rough comparison for equivalent ratings:
- A 650V/30A silicon superjunction MOSFET might cost $2-4
- An equivalent GaN HEMT costs $3-8
- A 1200V/40A silicon IGBT module costs $15-30
- An equivalent SiC MOSFET module costs $30-80
But these numbers miss the system-level savings. Smaller magnetics, reduced heatsinking, lower energy costs over the product lifetime, and higher power density often make the total system cost competitive or favorable for wide-bandgap designs even at today's premiums.
I think GaN below 650V will reach cost parity with silicon within 2-3 years for most applications. SiC at 1200V+ will take longer — maybe 5-7 years — because the substrate cost is structurally higher. The 200mm transition will help, but SiC wafers will never be as cheap as silicon wafers.
Both technologies are essential to the energy transition. Without SiC, EVs would be less efficient and have shorter range. Without GaN, our chargers and power supplies would be bigger, heavier, and waste more electricity. The power semiconductor industry's quiet revolution doesn't get the attention of AI chips, but its impact on daily life is arguably larger.