Power semiconductors

What is the main advantage of the trench gate structure in power MOSFETs, in which the gate is buried in a groove etched into the silicon?

  1. AThe gate capacitance becomes zero
  2. BThe breakdown voltage always doubles
  3. CCells can be packed densely to increase channel width and lower on-resistance
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Answer: C. Cells can be packed densely to increase channel width and lower on-resistance

In a trench gate structure, the channel forms vertically along the trench sidewalls, so more cells fit per unit area than in a planar device. This increases the total channel width and eliminates the resistance between adjacent cells (the JFET resistance), lowering on-resistance.

  • A. The gate capacitance does not disappear; it actually tends to increase.
  • B. The breakdown voltage is set mainly by the drift layer and does not double from the structure alone.
  • C. Correct. Denser cells lower the on-resistance.
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More Power semiconductors questions

  1. Which correctly describes the typical division of use between silicon MOSFETs and IGBTs?
  2. What is the main purpose of a snubber circuit in a power device switching circuit?
  3. When one switch of an inverter turns on, which loss increases due to the reverse recovery of the diode in the opposite arm?
  4. Among soft-switching techniques for power converters, which correctly describes ZVS (zero-voltage switching)?
  5. When a power MOSFET's gate is charged with a constant current, why does the gate voltage stay flat for a while (the Miller plateau)?