The neutral region formed at P-n junction due to recombination of electrons and holes is

Options

A. Fermi layer
B. Depletion layer
C. Acceptor layer
D. All the above

Answer

To solve the question regarding the neutral region formed at a P-N junction due to recombination of electrons and holes, 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. The P-type semiconductor has an abundance of holes (positive charge carriers), while the N-type semiconductor has an abundance of electrons (negative charge carriers).

**Hint**: Remember that P-type has holes and N-type has electrons.

2. **Recombination Process**:
- When the P-N junction is formed, electrons from the N-side move towards the P-side and recombine with holes. This recombination leads to the formation of fixed ions at the junction.

**Hint**: Think about how electrons and holes interact at the junction.

3. **Formation of the Depletion Region**:
- As electrons recombine with holes, they leave behind charged ions (positive ions on the P-side and negative ions on the N-side). This creates a region around the junction that is devoid of free charge carriers, known as the depletion region.

**Hint**: Focus on the concept of charge neutrality and how it changes at the junction.

4. **Characteristics of the Depletion Region**:
- The depletion region is characterized by the absence of free electrons and holes, leading to a built-in electric field due to the fixed ions. This region acts as an insulator and prevents further movement of charge carriers across the junction.

**Hint**: Consider the role of the electric field in the depletion region.

5. **Identifying the Correct Term**:
- The question asks for the term that describes the neutral region formed at the P-N junction due to recombination. The correct term for this region is the "depletion layer".

**Hint**: Recall the terminology used in semiconductor physics.

### Final Answer:
The neutral region formed at the P-N junction due to the recombination of electrons and holes is called the **depletion layer**.