In a doped semiconductor, the impurity level is 40 meV above the valence band. The semicoductor is

Options

A. n-type
B. p-type
C. intrinsic
D. extrinsic

Answer

To determine the type of semiconductor based on the given impurity level of 40 meV above the valence band, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Energy Bands**: In a semiconductor, the energy bands are divided into the valence band (where electrons are present) and the conduction band (where electrons can move freely). The energy gap between these bands is known as the bandgap.

2. **Identify the Impurity Level**: The question states that the impurity level is 40 meV above the valence band. This means that the energy level introduced by the dopant is close to the valence band.

3. **Determine the Type of Doping**:
- **p-type Semiconductor**: In a p-type semiconductor, acceptor impurities are added, which create energy levels just above the valence band. Electrons from the valence band can jump to these acceptor levels, leaving behind holes in the valence band.
- **n-type Semiconductor**: In an n-type semiconductor, donor impurities are added, which create energy levels just below the conduction band. These donor levels provide extra electrons that can easily move to the conduction band.

4. **Analyze the Given Energy Level**: Since the impurity level is 40 meV above the valence band, it suggests that this is an acceptor level. Electrons can easily jump from the valence band to this level, creating holes in the valence band.

5. **Conclusion**: Since the impurity level is above the valence band, the semiconductor is p-type.

### Final Answer:
The semiconductor is **p-type**.

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