Which among the following atom is donor impurity?

Options

A. A1
B. B
C. Ga
D. P

Answer

To determine which atom among the given options is a donor impurity, we need to analyze the valence electrons of each element listed.

### Step-by-Step Solution:

1. **Identify the Elements**: The question provides four options: Aluminum, Boron, Gallium, and Phosphorus.

2. **Determine the Group**:
- Aluminum (Al), Boron (B), and Gallium (Ga) are all part of Group 13 of the periodic table, also known as the Boron family.
- Phosphorus (P) is part of Group 15.

3. **Count Valence Electrons**:
- Aluminum (Al) has 3 valence electrons.
- Boron (B) has 3 valence electrons.
- Gallium (Ga) has 3 valence electrons.
- Phosphorus (P) has 5 valence electrons.

4. **Identify Donor and Acceptor Impurities**:
- Donor impurities are typically elements that have more valence electrons than the semiconductor material (like silicon, which has 4 valence electrons). These elements can donate extra electrons to the conduction band.
- In this case, Phosphorus, with its 5 valence electrons, can donate an extra electron when doped into silicon, making it a donor impurity.

5. **Conclusion**: Among the given options, Phosphorus (P) is the donor impurity.

### Final Answer:
Phosphorus (P) is the donor impurity.

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