PN junctions and diodes
How does the built-in (diffusion) potential of a PN junction relate to the doping on each side?
- AIt is constant, independent of doping
- BIt decreases as doping increases
- CIt increases as doping increases
Show answer and explanation
Answer: C. It increases as doping increases
The built-in potential is Vbi = (kT/q) ln(NA × ND / ni²), so it increases with the doping on both sides. For silicon PN junctions it is typically about 0.6–0.9 V.