IGBT vs Power MOSFET: Which to Use for What

Both are voltage-controlled power switches with an insulated gate, but they conduct differently. A power MOSFET carries current with one type of carrier and behaves like a resistor, so it is fast and efficient at low and medium voltage. An IGBT adds a bipolar output stage that floods the device with carriers, which keeps conduction loss low at high voltage and current, but makes turn-off slower. The usual split is MOSFETs below a few hundred volts or at high frequency, and IGBTs at high voltage and power.

AspectPower MOSFETIGBT
StructureUnipolar: majority carriers only, controlled by a MOS gateMOS gate driving a bipolar output stage, so both electrons and holes take part
Typical voltage rangeFrom a few volts up to about 900 V (silicon); SiC MOSFETs reach several kVAbout 600 V up to several kV
On-state lossResistive (RDS(on)); rises steeply as the voltage rating increasesNearly fixed saturation voltage (about 1.5 to 3 V); lower loss at high voltage and high current
Switching speedFast: tens or hundreds of kHz, and higherSlower: usually up to a few tens of kHz
Turn-off tail currentNoneYes: stored minority carriers keep current flowing briefly
Body diodeBuilt inNone: a separate antiparallel diode is added in the package
Parallel operationEasy: on-resistance rises with temperature, so current spreads outPossible, but needs more care
Gate driveVoltage-driven, with gate charge to supply at each switching eventVoltage-driven, about 15 V typically
Typical usesSwitching power supplies, DC-DC converters, chargers, low-voltage motor drivesElectric-vehicle inverters (silicon IGBTs), industrial motor drives, trains, welding, grid equipment

Figures are typical orders of magnitude and vary by process generation and product.

When to use which

Power MOSFET
When switching frequency is high and the voltage is not too high: power supplies, converters, battery-powered motor drives.
IGBT
When voltage and current are high and frequency is moderate: traction inverters, industrial drives, heavy equipment.
Trend
SiC MOSFETs are taking over part of the IGBT range, offering high voltage with fast switching and low loss.

FAQ

When should I choose an IGBT over a MOSFET?

At high voltage and high current (roughly 600 V and above) with a moderate switching frequency, where the low and nearly fixed conduction voltage of an IGBT gives lower loss.

Why is an IGBT slower at turn-off?

Stored minority carriers keep current flowing for a short time after the gate turns off. This tail current limits the switching frequency.

Does an IGBT have a body diode?

No. A separate antiparallel diode is added in the package to carry reverse current.

Are SiC MOSFETs replacing IGBTs?

Partly. SiC MOSFETs offer high voltage with fast switching and low loss, so they are taking over part of the IGBT range, such as electric-vehicle inverters.

Check your understanding

Which correctly describes an IGBT?

  1. AA two-terminal device with only two PN junctions
  2. BA device driven by a MOS gate that achieves a low on-state voltage through conductivity modulation from bipolar operation
  3. CA thyristor turned on by light
Show answer and explanation

Answer: B. A device driven by a MOS gate that achieves a low on-state voltage through conductivity modulation from bipolar operation

An IGBT combines a MOSFET input with a bipolar output, adding a p+ layer on the drain side of a MOSFET-like structure. It is voltage-driven, simplifying gate drive, and when on, holes injected from the p+ layer sharply reduce drift-layer resistance (conductivity modulation), keeping on-voltage low even at 600 V to 6.5 kV ratings. It is the workhorse of EV, rail and industrial inverters, though tail current makes it unsuitable for high frequencies.

Which correctly describes the typical division of use between silicon MOSFETs and IGBTs?

  1. AMOSFETs suit fast switching at relatively low voltages, while IGBTs suit high voltages of several hundred volts or more and large currents
  2. BIGBTs suit low voltage and small current, while MOSFETs suit high voltage and large current
  3. CBoth can only be used for the same applications
Show answer and explanation

Answer: A. MOSFETs suit fast switching at relatively low voltages, while IGBTs suit high voltages of several hundred volts or more and large currents

Silicon MOSFETs use only majority carriers and switch fast, but on-resistance soars at high voltage, so they serve mostly below a few hundred volts, especially in low-voltage supplies. IGBTs keep on-voltage low at high voltage through conductivity modulation, suiting high-current uses above 600 V (EVs, industrial inverters, rail), though tail current slows them. SiC MOSFETs are now displacing both in the mid-to-high-voltage range.

At IGBT turn-off, what is the phenomenon called in which the current does not drop to zero immediately but trails off because of stored minority carriers?

  1. AInrush current
  2. BTail current
  3. CDark current
Show answer and explanation

Answer: B. Tail current

An IGBT lowers drift resistance by injecting minority carriers (holes) when on, so at turn-off current continues until they recombine or are swept out—the tail current. Because it flows while the voltage is already high, it is a major source of turn-off loss and limits IGBT switching frequency to tens of kHz or less. Lifetime control and field-stop structures shorten it. MOSFETs have no tail current.

  1. Which correctly describes the difference in how bipolar transistors and MOSFETs are controlled?
  2. Power MOSFETs are easy to use in parallel. Which statement about the temperature dependence of on-resistance explains why?
  3. Why is a negative gate voltage (for example, −3 to −5 V) sometimes applied to SiC MOSFETs or IGBTs in the off state?

Practice Power semiconductors questions

Key terms explained

IGBT
Insulated-gate bipolar transistor. Driven by a MOS gate, it achieves a low on-state voltage even at high voltage ratings through conductivity modulation.
Power MOSFET
A MOSFET built to handle large currents and voltages. It switches quickly and is widely used in power supply circuits and the like.
Super-junction MOSFET
A power MOSFET whose drift layer has alternating p-type and n-type pillars. It allows higher drift-layer doping without losing breakdown voltage, achieving on-resistance below the conventional silicon limit.
Gate driver
A circuit that receives control signals and drives a power device's gate with the right voltage and enough current. Many include isolation or level shifting to drive high-side switches.

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