Zener breakdown occurs in a p-n junction having p and n both :

Options

A. lightly doped and have wide depletion layer.
B. heavily doped and have narrow depletion layer.
C. lightly doped and have narrow depletion layer.
D. heavily doped and have wide depletion layer.

Answer

To solve the question regarding Zener breakdown in a p-n junction, let's break down the explanation step-by-step.

### Step-by-Step Solution:

1. **Understanding the p-n Junction**:
- A p-n junction is formed by joining p-type and n-type semiconductors. The p-side has an abundance of holes (positive charge carriers), while the n-side has an abundance of electrons (negative charge carriers).

2. **Depletion Layer**:
- At the junction of the p-type and n-type materials, a depletion layer is formed. This layer is neutral, meaning the number of holes and electrons is equal, but it is characterized by a lack of mobile charge carriers.

3. **Doping Levels**:
- Zener breakdown occurs when both the p-side and n-side are heavily doped. Heavy doping increases the concentration of charge carriers (holes in p-side and electrons in n-side), which leads to a significant increase in the density of charge carriers in the depletion layer.

4. **Thin Depletion Layer**:
- Due to heavy doping, the depletion layer becomes very thin. This thin layer is crucial because it allows for a stronger electric field to develop across it when a potential difference is applied.

5. **Applying Potential Difference**:
- When a potential difference is applied across the p-n junction, an electric field is established in the depletion layer. The strength of this electric field is given by the formula \( E = \frac{V}{d} \), where \( V \) is the potential difference and \( d \) is the thickness of the depletion layer.

6. **High Electric Field Effects**:
- The thin nature of the depletion layer, combined with the high electric field, leads to the excitation of electrons and holes. This results in the formation of electron-hole pairs, which is the mechanism behind Zener breakdown.

7. **Conclusion**:
- Therefore, Zener breakdown occurs in a p-n junction that is heavily doped on both sides, leading to a narrow depletion layer. This allows for a high electric field to be established, facilitating the breakdown process.

### Final Answer:
Zener breakdown occurs in a p-n junction that is heavily doped on both sides, resulting in a narrow depletion layer.