PN junctions and diodes
How does the depletion width of a one-sided abrupt junction depend on the reverse bias voltage V (when V is much larger than the built-in potential)?
- AIt is proportional to V
- BIt is proportional to V squared
- CIt is roughly proportional to the square root of V
Show answer and explanation
Answer: C. It is roughly proportional to the square root of V
The depletion width of a one-sided abrupt junction is W ∝ √(Vbi + V), so for large V it is roughly proportional to √V. The junction capacitance therefore decreases roughly as 1/√V. The lower the doping on the lightly doped side, the wider the depletion layer.