What is meant by 'doping' in a semiconductor ?

Explanation

### Step-by-Step Text Solution

1. **Definition of Doping**: Doping in semiconductors refers to the process of intentionally adding impurities to an intrinsic (pure) semiconductor material to enhance its electrical conductivity.

2. **Purpose of Doping**: The primary purpose of doping is to increase the number of charge carriers (electrons or holes) in the semiconductor, which improves its ability to conduct electricity.

3. **Types of Doping**: Doping can be classified into two main types based on the nature of the impurity added:
- **N-type Doping**: In this process, a pentavalent impurity (such as phosphorus) is added to the semiconductor (like silicon). Phosphorus has five valence electrons, while silicon has four. The extra electron from phosphorus becomes a free charge carrier, increasing the conductivity of the semiconductor.
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