What are p-type and n-type semiconductors?

Answer

### Step-by-Step Solution

1. **Definition of Semiconductors**:
Semiconductors are materials that have electrical conductivity between that of conductors and insulators. They can conduct electricity under certain conditions.

2. **Understanding P-Type Semiconductors**:
- **Majority and Minority Carriers**: In a p-type semiconductor, the majority charge carriers are holes. Holes are created when electrons leave their positions in the valence band, creating a positive charge.
- **Doping with Trivalent Impurities**: P-type semiconductors are formed by doping a pure semiconductor (like silicon) with trivalent impurities (elements with three valence electrons), such as boron or aluminum. This process introduces holes into the material.
- **Energy Levels**: In p-type semiconductors, the acceptor energy level (created by the trivalent impurity) is close to the valence band and far from the conduction band.

3. **Understanding N-Type Semiconductors**:
- **Majority and Minority Carriers**: In an n-type semiconductor, the majority charge carriers are electrons. These electrons are added to the conduction band, increasing the material's conductivity.
- **Doping with Pentavalent Impurities**: N-type semiconductors are created by doping a pure semiconductor with pentavalent impurities (elements with five valence electrons), such as phosphorus, arsenic, or antimony. This process adds extra electrons to the material.
- **Energy Levels**: In n-type semiconductors, the donor energy level (created by the pentavalent impurity) is close to the conduction band and far from the valence band.

4. **Summary of Differences**:
- **P-Type**: Majority carriers are holes, formed by trivalent doping, with acceptor energy levels close to the valence band.
- **N-Type**: Majority carriers are electrons, formed by pentavalent doping, with donor energy levels close to the conduction band.