What is a SiC MOSFET?

A silicon carbide (SiC) MOSFET is a power semiconductor device that uses silicon carbide as its base material to switch and control electrical power. Like a conventional MOSFET, it turns current on and off through a gate voltage. The difference lies in the material: silicon carbide is a wide-bandgap semiconductor, meaning it can withstand higher electric fields and temperatures than ordinary silicon.

This wide bandgap (3.26 eV), roughly three times that of silicon, gives a SiC MOSFET device the ability to block high voltages across a thinner, more conductive layer. This single material property cascades into a set of performance advantages that silicon cannot replicate, regardless of how well the device is engineered.

Infineon's CoolSiC™ MOSFET family spans 650 V to 1700 V and delivers best-in-class RDS(on), switching performance, and reliability for the most demanding power conversion applications. Built on Infineon's proprietary trench gate cell technology, CoolSiC™ devices achieve lower conduction losses and superior gate oxide reliability compared to planar SiC designs. For automotive applications, Infineon offers a dedicated AEC-Q101-qualified discrete lineup for voltages of 400 V to 2000 V and automotive-grade power modules.

Explore Infineon’s CoolSiC™ MOSFET Portfolio

How does a SiC MOSFET work?

A MOSFET is a three-terminal device (gate, drain, and source) that acts as an electrically controlled switch. Applying a voltage to the gate creates a conductive channel between drain and source, allowing current to flow. 

The role of Kelvin pin in CoolSiC™ MOSFETs

Although MOSFETs are commonly described as three-terminal devices, most Infineon CoolSiC™ MOSFETs are 4-pin devices. The fourth pin is the Kelvin pin, an isolated gate control pin that helps improve gate control during fast switching.

Close-up of a semiconductor wafer used to produce advanced SiC MOSFETs and power devices for industrial, automotive, and energy applications.

Silicon carbide (SiC) semiconductor wafer

Remove that gate voltage and the channel disappears, blocking current. The transistor is either fully on or fully off, and the speed and efficiency of that switching action defines the performance of the entire power conversion system.

Because silicon carbide conducts heat about three times better than silicon and tolerates electric fields nearly ten times stronger, a SiC MOSFET can be designed with a much thinner drift region. A thinner region means lower on-resistance (RDS(on)), which translates directly into reduced conduction losses. The device also switches faster, cutting the energy lost during each on-off transition.

Why choose a SiC MOSFET? Features and benefits explained

The performance gap between SiC and silicon is rooted in physics, not manufacturing. Silicon carbide's material properties allow device designers to achieve what silicon fundamentally cannot.

  • Higher breakdown electric field: SiC withstands electric fields ~10× stronger than silicon before avalanche breakdown. This allows thinner, more heavily doped drift layers for a given voltage rating.
    The advantage grows with voltage: at 200 V and below, silicon remains competitive; above 650 V, the SiC drift layer advantage becomes decisive, enabling RDS(on) values that silicon devices at equivalent voltage ratings simply cannot match.
  • Higher operating temperature: Where silicon is limited to 150–175°C junction temperature, Infineon’s CoolSiC™ MOSFET Gen2 devices are rated for a maximum virtual junction temperature. This supports reliable operation in thermally demanding environments and helps designers optimize cooling requirements in applications such as automotive under-hood systems and industrial power systems.
  • Higher thermal conductivity: At ~490 W/m·K versus silicon's ~150 W/m·K, SiC removes heat from the junction roughly 3× faster, reducing thermal runaway risk and enabling higher power density in the same package footprint
  • Higher switching frequency: Lower parasitic capacitances allow SiC MOSFETs to switch at up to 300–500 kHz, compared to silicon's practical ~100 kHz limit at high voltage. Higher frequency means smaller inductors, capacitors, and transformers, which leads to smaller, lighter systems

Bottom Line: The numbers tell a clear story: SiC's 10× higher breakdown field and 3× better thermal conductivity are not incremental improvements, they are material-level advantages that compound into dramatically better system efficiency, power density, and thermal performance, particularly above 650 V.

Should I choose SiC for my design?

It depends primarily on voltage and switching frequency. If your system operates below 600 V at moderate frequencies, silicon MOSFETs remain cost-effective and well-proven.

Above 650 V, particularly where switching frequency, efficiency, power density, or operating temperature are being pushed, SiC delivers system-level advantages that silicon cannot match. Factor in total cost of ownership, not just device price: the efficiency gains from SiC typically reduce heatsink size, passive component size, and energy losses over the product's lifetime, often offsetting the higher upfront device cost in medium- to high-power applications.

Want to know if it is the right time to adopt SiC?

Discover when to move to SiC in this blog

How does a SiC MOSFET compare to an IGBT?

The most relevant comparison for engineers designing high-voltage power systems is not SiC vs. silicon MOSFET — it is SiC MOSFET vs. IGBT. For decades, the insulated gate bipolar transistor (IGBT) was the device of choice for high-voltage, high-current applications. SiC MOSFETs are now displacing IGBTs across a growing range of use cases.

SiC MOSFET vs IGBT: key differences

Why is the SiC MOSFET 1200 V so widely used?

The SiC MOSFET 1200 V is one of the most popular SiC devices because its voltage rating matches the needs of many high-power applications. It fits the DC-link voltages common in electric vehicles, solar inverters, and industrial motor drives.

At 1200 V, silicon alternatives struggle with high losses and slow switching. A 1200 V SiC MOSFET delivers the blocking capability these systems require while keeping efficiency high and components compact.

Worth noting

A SiC MOSFET 1200 V can achieve on-resistance values that would require a silicon device roughly ten times larger in die area to match. That size reduction translates directly into smaller packages, lower capacitances, faster switching, and higher power density.

Frequently asked questions about SiC MOSFET

1. What are the key design challenges when using SiC MOSFETs?

While designing with SiC MOSFETs, the main challenges are managing fast switching speeds, minimizing EMI, optimizing PCB layout, and selecting the appropriate gate driver.

1200 V SiC MOSFETs match the voltage requirements of modern EV powertrains while delivering higher efficiency, longer driving range, and reduced cooling requirements.

Use a multimeter to verify the body diode and gate integrity, then perform switching tests such as a double-pulse test to evaluate dynamic performance.

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