In a `p-n` junction diode, the barrier potential opposes diffusion of

Options

A. minority carrier in both regions only
B. majority carriers only
C. electrons in p region
D. holes in p region

Explanation

To solve the question regarding the barrier potential in a p-n junction diode, we can break down the explanation into clear steps:

### Step-by-Step Solution:

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

2. **Diffusion of Charge Carriers**:
- When the p-n junction is formed, holes from the p-region tend to diffuse into the n-region, and electrons from the n-region tend to diffuse into the p-region due to concentration gradients. This movement is called diffusion.

3. **Recombination**:
- As holes and electrons diffuse across the junction, they can recombine. This recombination leads to a depletion of charge carriers in the junction area, creating a region devoid of free charge carriers known as the depletion region.

4. **Formation of Barrier Potential**:
- The depletion region creates an electric field due to the fixed charges left behind (ionized donors in the n-region and ionized acceptors in the p-region). This electric field establishes a potential difference known as the barrier potential.

5. **Opposition to Further Diffusion**:
- The barrier potential acts to oppose further diffusion of charge carriers across the junction. It prevents majority carriers (holes in the p-region and electrons in the n-region) from moving freely across the junction.

6. **Conclusion**:
- Therefore, the barrier potential specifically opposes the further movement of majority carriers only, which leads us to conclude that the correct answer to the question is "majority carriers only".

### Final Answer:
The barrier potential in a p-n junction diode opposes the diffusion of **majority carriers only**.

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