In an intrinsic semiconductor at room temperature, number of electrons and holes are

Options

A. unequal
B. equal
C. infinite
D. zero

Answer

To solve the question regarding the number of electrons and holes in an intrinsic semiconductor at room temperature, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Intrinsic Semiconductors**:
- An intrinsic semiconductor is a pure semiconductor material without any significant dopant species present. Common examples include silicon (Si) and germanium (Ge).

2. **Valency of Semiconductor Atoms**:
- The atoms in intrinsic semiconductors have a valency of four. This means each atom can form four covalent bonds with neighboring atoms.

3. **Behavior at Absolute Zero**:
- At absolute zero (0 Kelvin), all the valence electrons are in the valence band and are tightly bound to their respective atoms. Therefore, there are no free charge carriers (electrons or holes) available for conduction.

4. **Effect of Temperature**:
- As the temperature increases (like at room temperature), thermal energy causes some valence electrons to gain enough energy to break free from their bonds. This process creates free electrons in the conduction band.

5. **Creation of Holes**:
- When a valence electron leaves its bond, it creates a "hole" in the valence band. This hole acts as a positive charge carrier.

6. **Equal Number of Electrons and Holes**:
- In intrinsic semiconductors, the number of free electrons generated is equal to the number of holes created. This is because each electron that becomes free leaves behind a hole.

7. **Conclusion**:
- Therefore, at room temperature in an intrinsic semiconductor, the number of electrons (n) is equal to the number of holes (p). This can be expressed as n = p.

### Final Answer:
At room temperature, the number of electrons and holes in an intrinsic semiconductor are equal.