Depletion layer in the p-n junction consists of

Options

A. electrons
B. holes
C. positive and negative ions fixed in their position
D. both electron and holes

Answer

To solve the question regarding the composition of the depletion layer in a p-n junction, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding p-n Junction**:
- A p-n junction is formed by joining p-type and n-type semiconductors.
- In p-type semiconductors, the majority charge carriers are holes (positive charge carriers), while in n-type semiconductors, the majority charge carriers are electrons (negative charge carriers).

2. **Charge Carrier Movement**:
- When the p-n junction is formed, holes from the p-type region diffuse into the n-type region, and electrons from the n-type region diffuse into the p-type region.
- This movement occurs because of the concentration gradient, where charge carriers move from a region of higher concentration to a region of lower concentration.

3. **Recombination of Charge Carriers**:
- As holes and electrons diffuse across the junction, they recombine. A hole from the p-type region can recombine with an electron from the n-type region, effectively neutralizing each other.
- This recombination process leads to the formation of a depletion region, where there are very few free charge carriers.

4. **Formation of the Depletion Layer**:
- The depletion layer is characterized by a lack of free charge carriers (both holes and electrons) because they have recombined.
- The region becomes depleted of mobile charge carriers, hence the name "depletion layer."

5. **Conclusion**:
- The depletion layer in a p-n junction consists of fixed ionized donor and acceptor atoms. The p-type side has negatively charged acceptor ions (due to the absence of holes), and the n-type side has positively charged donor ions (due to the absence of electrons).
- Therefore, the depletion layer is formed from the ionized atoms of the p-type and n-type materials, not from free electrons or holes.

### Final Answer:
The depletion layer in the p-n junction consists of fixed ionized donor and acceptor atoms.