If a small amount of antimony is added to germanium crystal

Options

A. the antimony becomes an acceptor atom
B. three will be more free electrons than holes in the semiconductor
C. its resistance is increased
D. it becomes a p-type semiconductor

Answer

To solve the question of what happens when a small amount of antimony is added to a germanium crystal, we can follow these steps:

### Step 1: Understand the Types of Semiconductors
- **Germanium (Ge)** is a tetravalent semiconductor, meaning it has four valence electrons and can form four covalent bonds with neighboring atoms.
- **Antimony (Sb)** is a pentavalent element, meaning it has five valence electrons.

**Hint:** Remember the difference between tetravalent and pentavalent elements and how they bond.

### Step 2: Analyze the Doping Process
- When antimony is introduced into the germanium crystal lattice, it replaces some of the germanium atoms.
- Each antimony atom can form bonds with four neighboring germanium atoms, but it has one extra electron that does not participate in bonding.

**Hint:** Visualize the crystal structure and how antimony fits into the lattice of germanium.

### Step 3: Determine the Effect on Electron Concentration
- The extra electron from each antimony atom becomes a free electron in the conduction band of the semiconductor.
- This means that for every antimony atom added, there is an increase in the number of free electrons available for conduction.

**Hint:** Consider how the addition of free electrons affects the electrical properties of the material.

### Step 4: Classify the Type of Semiconductor
- Since the addition of antimony results in more free electrons than holes (which are the absence of electrons), this type of doping is known as n-type doping.
- In n-type semiconductors, the majority carriers are electrons, while holes are the minority carriers.

**Hint:** Recall the definitions of n-type and p-type semiconductors and how they relate to the majority and minority charge carriers.

### Step 5: Conclusion
- Therefore, when a small amount of antimony is added to germanium, it becomes an n-type semiconductor due to the increased concentration of free electrons.

**Final Answer:** The germanium crystal becomes an n-type semiconductor.

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