To get a n- type semiconductor from silicon , it should be doped with a substance with valency

Options

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

Answer

To determine the correct valency of the substance needed to dope silicon to create an n-type semiconductor, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Semiconductors**:
- A semiconductor is a material that has electrical conductivity between that of a conductor and an insulator. Silicon (Si) is a commonly used semiconductor.

2. **Types of Semiconductors**:
- There are two types of semiconductors: n-type and p-type.
- N-type semiconductors are formed when silicon is doped with elements that have more valence electrons than silicon.

3. **Valency of Silicon**:
- Silicon has a valency of 4, meaning it has four valence electrons.

4. **Doping Silicon**:
- To create an n-type semiconductor, we need to introduce an impurity that has more than four valence electrons. This will provide extra electrons to the silicon lattice.

5. **Choosing the Right Dopant**:
- The options given are valencies of 2, 1, 3, and 5.
- We need to select a dopant with a valency greater than 4.

6. **Identifying Suitable Dopants**:
- Elements such as phosphorus (P) and arsenic (As) are commonly used as dopants for silicon to create n-type semiconductors.
- Both phosphorus and arsenic have a valency of 5.

7. **Conclusion**:
- Therefore, to get an n-type semiconductor from silicon, it should be doped with a substance that has a valency of 5.

### Final Answer:
To get an n-type semiconductor from silicon, it should be doped with a substance with valency **5**.

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