In a p -n junction, a) new holes and conduction electrons are produced continuously throughout the material b) new holes and conduction electrons are produced continuously throughout the material except in the depletion region c) holes and conduction electrons recombine continuously throughout the material d) holes and conduction electrons recombine continuously throughout the material except in the depletion region.

Options

A. Only a and d are correct
B. Only b and c are correct
C. Only a, b and c are correct
D. All are correct

Answer

To solve the question regarding the behavior of holes and conduction electrons in a p-n junction, we will analyze each statement provided and determine their validity based on our understanding of semiconductor physics.

### Step-by-Step Solution:

1. **Understanding the p-n Junction**:
- A p-n junction consists of a p-type semiconductor (which has an abundance of holes) and an n-type semiconductor (which has an abundance of electrons). Between these two regions, there exists a depletion region where no free charge carriers are present.

2. **Analyzing Statement A**:
- **Statement A**: "New holes and conduction electrons are produced continuously throughout the material."
- **Analysis**: In a semiconductor, holes and electrons are indeed generated continuously due to thermal excitation. Therefore, this statement is **true**.

3. **Analyzing Statement B**:
- **Statement B**: "New holes and conduction electrons are produced continuously throughout the material except in the depletion region."
- **Analysis**: While it is true that holes and electrons are produced throughout the material, the depletion region is devoid of free charge carriers due to recombination. However, generation still occurs in the material surrounding the depletion region. Thus, this statement is **false**.

4. **Analyzing Statement C**:
- **Statement C**: "Holes and conduction electrons recombine continuously throughout the material."
- **Analysis**: Holes and electrons do recombine, but this recombination does not occur uniformly throughout the material. It is particularly significant in the regions outside the depletion zone. Therefore, this statement is **false**.

5. **Analyzing Statement D**:
- **Statement D**: "Holes and conduction electrons recombine continuously throughout the material except in the depletion region."
- **Analysis**: This statement is accurate because recombination does not occur in the depletion region, where there are no free charge carriers. Thus, this statement is **true**.

6. **Conclusion**:
- The correct statements are A and D. Therefore, the answer to the question is that statements A and D are true.

### Final Answer:
The correct statements are:
- A) New holes and conduction electrons are produced continuously throughout the material. (True)
- D) Holes and conduction electrons recombine continuously throughout the material except in the depletion region. (True)