Introduction / Context:
The reverse-bias behavior of a p-n junction diode is central to semiconductor device physics. Above a critical reverse voltage, the junction can undergo breakdown due to avalanche multiplication (or Zener tunneling at lower voltages in heavily doped junctions).
Given Data / Assumptions:
- Device: p-n junction diode.
- Bias: high reverse voltage applied.
- Possible breakdown mechanisms: avalanche effect, Zener effect.
Concept / Approach:
In avalanche breakdown, minority carriers accelerated by a strong electric field gain sufficient energy to ionize atoms by impact, creating new electron-hole pairs and triggering a chain reaction that sharply increases current.
Step-by-Step Solution:
Step 1: Apply large reverse voltage across the junction.Step 2: Depletion region electric field increases substantially.Step 3: Carriers gain kinetic energy and cause impact ionization.Step 4: Carrier multiplication produces avalanche breakdown.Step 5: Therefore, A is true and R correctly explains A.
Verification / Alternative check:
Compare with Zener breakdown (field emission) at lower voltages for heavily doped junctions; for higher voltages and lighter doping, avalanche dominates, matching the assertion.
Why Other Options Are Wrong:
B: R is directly causative, not merely correlated.C: R is not false.D: A is not false; avalanche breakdown is real.E: Both statements are not false.
Common Pitfalls:
Confusing avalanche with Zener breakdown; ignoring doping dependence of the dominant mechanism.
Final Answer:
Both A and R are true and R is correct explanation of A
Discussion & Comments