Question

In the depletion region of an unbiased PN junction diode there are _______

• A. Only electrons
• B. Only holes
• C. Both electrons and holes
• D. Only fixed ions

Answer 1

The correct option is D

Only fixed ions

P-N junction:

1. A P-N junction is formed when a P-type semiconductor is mixed with an N-type semiconductor.
2. There is a very thin region called the depletion region in the middle.
3. In this region, all the holes and the electrons from both sides combine together, and hence only ions remain.

Explanation for the correct option:

Option D:

1. As only fixed ions are present in the depletion region, this is the correct option.

Explanation for the incorrect options:

Option A:

1. Other option states that only electrons or only holes or both electron or holes are present in the depletion region.
2. But the electrons combine with the holes and form fixed ions.
3. Hence, this option (A), (B) and (C) are incorrect.

Hence, option D is the correct option.