Depletion layer consists of

Options

A. electrons
B. protons
C. mobile charge
D. immobile ions

Answer

To answer the question "What does the depletion layer consist of?", we can break down the explanation step by step:

### Step-by-Step Solution:

1. **Understanding the Depletion Layer**:
- The depletion layer is formed at the junction of p-type and n-type semiconductors. It is a region where mobile charge carriers (electrons and holes) are depleted.

2. **Charge Carriers in Semiconductors**:
- In p-type semiconductors, holes are the majority charge carriers, while in n-type semiconductors, electrons are the majority charge carriers.

3. **Formation of the Depletion Region**:
- When a p-n junction is formed, electrons from the n-region diffuse into the p-region and recombine with holes. This recombination reduces the number of free charge carriers in the vicinity of the junction, leading to the formation of the depletion region.

4. **Immobile Charge Carriers**:
- The depletion region consists of ionized donor and acceptor atoms. In the p-region, the acceptor atoms (which create holes) become positively charged after losing their electrons. In the n-region, the donor atoms (which provide electrons) become negatively charged after donating their electrons.

5. **Characteristics of the Depletion Layer**:
- The depletion layer is characterized by the presence of immobile charge carriers, which are the ionized atoms left behind after the charge carriers have recombined. These immobile ions create an electric field that affects the movement of charge carriers in the junction.

6. **Conclusion**:
- Therefore, the depletion layer consists of immobile charge carriers, specifically the ionized donor and acceptor atoms that remain after the mobile charge carriers have recombined.

### Final Answer:
The depletion layer consists of immobile charge carriers, specifically the ionized donor and acceptor ions.