The GATE Grind

GATE 2026 EC – Question 14

Electronic Devices · P-N Junction and Semiconductor Devices · 1 mark · Multiple choice

Consider carrier transport in a Zener diode in the breakdown region. Which is the dominant transport mechanism for current flow in this case?

  1. Drift
  2. Diffusion
  3. Tunneling
  4. Ballistic transport

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Show answer and explanation

Correct answer: (C) Tunneling

Explanation

In a heavily doped Zener diode the depletion region is very thin. Zener breakdown is band-to-band tunneling under a strong electric field.