If we mix a pentavalent impurity in the crystal lattice of germinium the type of semiconductor formed will be:

Options

A. n-type semiconductor
B. p-type semiconductor
C. Both (1) & (2)
D. None of these

Answer

To determine the type of semiconductor formed when a pentavalent impurity is mixed into the crystal lattice of germanium, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Types of Semiconductors**:
- There are two main types of semiconductors: n-type and p-type.
- N-type semiconductors are formed when a semiconductor (like silicon or germanium) is doped with pentavalent impurities (elements from group 15 of the periodic table).
- P-type semiconductors are formed when a semiconductor is doped with trivalent impurities (elements from group 13).

2. **Identify the Pentavalent Impurity**:
- Pentavalent impurities are elements that have five valence electrons. Examples include phosphorus (P), arsenic (As), and antimony (Sb).
- When these elements are introduced into the crystal lattice of a semiconductor, they contribute extra electrons.

3. **Doping Germanium with Pentavalent Impurities**:
- Germanium (Ge) is a group 14 element that has four valence electrons.
- When a pentavalent impurity like phosphorus is added to germanium, the phosphorus atom will form covalent bonds with four germanium atoms, using four of its five valence electrons.
- The fifth electron from the phosphorus atom becomes free to move within the crystal lattice.

4. **Resulting Charge Carriers**:
- The extra free electron from the pentavalent impurity increases the number of negative charge carriers (electrons) in the semiconductor.
- This results in higher electrical conductivity.

5. **Conclusion**:
- Since the addition of pentavalent impurities leads to an increase in free electrons, the type of semiconductor formed is an n-type semiconductor.

### Final Answer:
The type of semiconductor formed when a pentavalent impurity is mixed in the crystal lattice of germanium is **n-type semiconductor**.

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