How can an n-type semiconductor be obtained from a pure crystal of germanium ?

Explanation

To obtain an n-type semiconductor from a pure crystal of germanium, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Pure Germanium**:
- Pure germanium (Ge) is a semiconductor that has four valence electrons. In its crystalline form, each germanium atom forms covalent bonds with four neighboring germanium atoms.

2. **Identify Doping**:
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