The emitter region in a PNP-junction transistor is more heavily doped than the base region, so that

Options

A. The flow across the base region will be only because of electrons
B. The flow across the base region will be only because of holes
C. Recombination will be decreased in the base region
D. Base current will be high

Answer

To solve the question regarding the doping levels in a PNP-junction transistor and its implications, we can break down the reasoning step by step:

### Step-by-Step Solution:

1. **Understanding Doping in PNP Transistor**:
- In a PNP transistor, the emitter is made of p-type material, and it is heavily doped with holes (positive charge carriers). The base is also p-type but is lightly doped.

2. **Role of Heavily Doped Emitter**:
- The heavy doping in the emitter means that there is a high concentration of holes available for conduction. This is crucial for the transistor's operation, as it allows for efficient injection of holes into the base region.

3. **Base Region Characteristics**:
- The base region, being lightly doped, has a lower concentration of holes compared to the emitter. This means that when holes are injected from the emitter into the base, there are fewer holes available to recombine with electrons.

4. **Recombination Process**:
- Recombination occurs when holes from the emitter meet electrons in the base. Since the base is lightly doped, the likelihood of recombination is reduced. This means that more holes can travel through the base without recombining.

5. **Conclusion on Recombination**:
- Since the emitter is heavily doped and the base is lightly doped, the number of recombinations in the base region is decreased. This allows for a greater number of holes to reach the collector region, enhancing the transistor's efficiency.

6. **Final Answer**:
- Therefore, the correct answer is that the recombination will be decreased in the base region due to the heavy doping of the emitter compared to the base.