Concept:Exceeding the reverse breakdown voltage provides minority carriers with sufficient kinetic energy to break covalent bonds via impact ionization, triggering carrier multiplication.
Formula:$$P_{\text{dissipated}} = V_{\text{breakdown}} \times I_{\text{reverse}} > P_{\text{max}}$$
Solution:- High electric fields accelerate minority carriers to high velocities.
- Collisions with lattice atoms create additional electron-hole pairs (avalanche multiplication).
- This causes reverse current to increase sharply. Without a series resistor to limit current, excessive power dissipation (\( P = V I \)) can cause thermal runaway and destroy the device.
Why other options are incorrect:- Option A: Breakdown increases reverse carrier multiplication under high field conditions; it does not narrow the depletion layer into forward bias.
- Option B: Reverse current increases rapidly rather than dropping to zero.
- Option D: The space-charge polarity remains unchanged; breakdown is an electrical conduction phenomenon.
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