Concept:In lightly doped diodes with wider depletion layers, minority carriers accelerated by the reverse electric field acquire high kinetic energy. When they collide with lattice atoms, they knock valence electrons free (impact ionization), creating new electron-hole pairs that accelerate and collide with more atoms, initiating an avalanche multiplication process.
Formula:$$\text{Avalanche Multiplication: } M = \frac{1}{1 - (V_r / V_{BR})^n}$$
Solution:- Minority carriers gain sufficient kinetic energy: \(E_k = q E \lambda\).
- High-energy collisions break covalent bonds (impact ionization).
- This creates a cascading chain reaction of carrier multiplication called Avalanche breakdown.
Why other options are incorrect:- Option A: Direct band-to-band tunneling describes Zener breakdown in heavily doped junctions.
- Option B: Avalanche breakdown is an electrical collision process, not a chemical reduction reaction.
- Option D: Fixed ions remain in the lattice; carrier multiplication is responsible for the current surge.
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