Technical note

GaN or SiC: choosing the device for your drive

Bitstream Dynamics

Gallium nitride and silicon carbide are both wide-bandgap semiconductors, and both beat silicon on switching speed and efficiency. That shared headline hides real structural differences that decide which one belongs in your design. Here is the short version, and the straight answer.

GaN: lateral, fast, low voltage

A GaN HEMT carries current sideways through a two-dimensional electron gas near the surface of the device. It is very fast, has very low switching loss, and, crucially, has no p-n body diode, so it does not suffer the reverse-recovery penalty that slows silicon and, to a lesser degree, SiC. Its comfort zone is lower voltage, roughly the tens of volts up to about 650 V. That makes it the natural fit for drone and robotics propulsion, servos, and other efficiency-driven, higher-frequency drives where the bus is modest and every watt of loss matters.

SiC: vertical, rugged, high voltage

A SiC MOSFET carries current straight down through a thick drift region that holds off the blocking voltage. That vertical structure is what lets it stand up to hundreds or thousands of volts, from 650 V into the multi-kilovolt range. It brings an intrinsic body diode, which is convenient for some topologies and a design consideration in others. Its home is high-voltage, high-power conversion: traction, industrial drives, high-voltage defense and aerospace systems, and the higher-voltage propulsion architectures on the horizon.

The straight answer

If your bus is below about 650 V and you are chasing efficiency, size, or switching speed, start with GaN. If your bus is above that, or you need serious power-handling and ruggedness, SiC is the device. The crossover around 650 V is genuinely contested today, and the right call there depends on cost, thermals, and the specific converter, which is exactly the kind of trade-off a short study resolves.

One thing that does not change with the device: the control. Our soft-switching and sensorless-control work is deliberately device-agnostic. The same loop that runs a GaN drive today ports to a SiC power stage as the voltage climbs, so the choice of switch does not lock you into a control architecture, or into us.

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