In a transistor

Options

A. emitter is more highly doped than collector
B. collector is more highly doped than emitter
C. both are equally doped
D. none of these

Answer

To solve the question regarding the doping levels in a transistor, we need to understand the structure and doping characteristics of the three regions in a bipolar junction transistor (BJT): the emitter, base, and collector.

### Step-by-Step Solution:

1. **Understand the Structure of a Transistor**:
A bipolar junction transistor (BJT) consists of three regions: the emitter, base, and collector. The emitter is responsible for injecting charge carriers into the base, while the collector collects these carriers.

2. **Doping Levels**:
- The **emitter** is heavily doped to ensure a high concentration of charge carriers (either electrons or holes, depending on the type of transistor).
- The **base** is lightly doped and thin to allow for efficient carrier transport.
- The **collector** is moderately doped, which is less than the emitter but more than the base.

3. **Analyze the Options**:
- **Option A**: Emitter is more highly doped than collector. This is true because the emitter has a higher doping concentration compared to the collector.
- **Option B**: Collector is more highly doped than emitter. This is false as established earlier.
- **Option C**: Both are equally doped. This is also false since the emitter is more heavily doped.
- **Option D**: None of these. This is incorrect as option A is true.

4. **Conclusion**:
Based on the doping characteristics of the transistor, the correct answer is **Option A**: Emitter is more highly doped than collector.

### Final Answer:
**Option A**: Emitter is more highly doped than collector.

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