In the middle of the depletion layer of reverse biased pn junction, which of the following is true?

potential is maximum

The correct answer is option 4: potential is maximum

In a reverse biased p–n junction, the depletion region widens because the majority carriers move away from the junction. The uncovered positive and negative ions in the depletion region create an electric field across the junction.

This electric field is strongest at the middle of the depletion layer (near the metallurgical junction) and gradually decreases towards the edges of the depletion region. Therefore, the electric field is maximum in the middle of the depletion region.

The confusion often arises between electric field and electric potential:

• The electric field is maximum at the center.
• The potential does not become maximum at the center; it changes continuously across the depletion region.