PN junctions and diodes
When a reverse bias is applied to an abrupt PN junction, where is the electric field strongest?
- AAt the junction interface where p-type meets n-type
- BAt the edges of the depletion layer
- CAt the contacts with the electrodes
Show answer and explanation
Answer: A. At the junction interface where p-type meets n-type
The field in the depletion layer is built up by integrating the charges of the ionized impurities; it is zero at the depletion layer edges and maximum at the metallurgical junction. Avalanche breakdown occurs when this maximum field reaches the critical field.
- A. Correct. The field peaks at the junction interface.
- B. The field is zero at the edges of the depletion layer.
- C. There is almost no field in the neutral regions near the electrodes.