Answer: Zener breakdown (quantum tunneling across thin depletion region).
- A Avalanche breakdown, which dominates instead in lightly doped junctions
- B Zener breakdown (quantum tunneling across thin depletion region)
- C Thermal breakdown caused by excessive self-heating of the junction
- D Ohmic breakdown caused by simple resistive heating at high current
Correct answer: B. Zener breakdown (quantum tunneling across thin depletion region)
Explanation: Zener breakdown: occurs in heavily doped junctions with thin depletion layer. Electrons tunnel from valence to conduction band. At < 5-6V typically.
Conductors have overlapping bands, semiconductors have a small energy gap that can be bridged by heat or doping, and insulators have a large gap that blocks conduction.
Concept context
Band theory, p-n junction, diodes, transistors, logic gates, and integrated circuits.