Power semiconductors

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
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Answer: B. Tail current

An IGBT injects minority carriers into the drift layer to lower its resistance when on, so at turn-off current keeps flowing until those carriers disappear. This is the tail current, which causes turn-off loss. MOSFETs have no minority-carrier storage, so they have no tail current.

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