To get `n`-type doped semiconductor, impurity to be added to silicon should have the following number of valence electrons

Options

A. 2
B. 5
C. 3
D. 1

Explanation

To determine the number of valence electrons required for an impurity to be added to silicon to create an n-type doped semiconductor, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Doping**:
- Doping is the process of adding impurities to a semiconductor to change its electrical properties. In the case of silicon, which has four valence electrons, we can add impurities to create either n-type or p-type semiconductors.

2. **Identify n-type Semiconductor**:
- An n-type semiconductor is formed when a pentavalent impurity is added to silicon. Pentavalent means that the impurity has five valence electrons.

3. **Determine the Valence Electrons of Silicon**:
- Silicon (Si) has four valence electrons in its outer shell.

4. **Identify the Type of Impurity for n-type Doping**:
- Pentavalent impurities are typically elements from Group 15 of the periodic table, such as phosphorus (P), arsenic (As), or antimony (Sb). These elements have five valence electrons.

5. **Conclusion**:
- To create an n-type semiconductor, the impurity added to silicon must have five valence electrons. Therefore, the correct answer is 5.

### Final Answer:
The impurity to be added to silicon to get an n-type doped semiconductor should have **5 valence electrons**.

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