*Question E6A04:
What is the name given to an impurity atom that adds holes to a semiconductor crystal structure?*  

*Correct Answer is  C: Acceptor impurity*  

### AI Response: (may contain errors)  

In semiconductor physics, impurities are intentionally added to a semiconductor to change its electrical properties. These impurities are known as dopants, and they can create either an excess of electrons or an excess of holes in the semiconductor material.

### Correct Answer: C: Acceptor impurity

1. **Why the correct answer is correct:**
   - An **acceptor impurity** is an impurity atom that, when added to a semiconductor, creates "holes" in the crystal structure. These holes are essentially the absence of an electron and can move through the lattice, allowing the semiconductor to conduct electricity. Acceptor impurities are typically elements from Group III of the periodic table, such as boron, which have one less valence electron than the semiconductor material (usually silicon or germanium).

### Why the other choices are incorrect:

2. **A: Insulator impurity**
   - An insulator impurity would not contribute to the conductivity of the semiconductor. Instead, it would increase the resistance, which is not the purpose of doping in semiconductors.

3. **B: N-type impurity**
   - An N-type impurity is the opposite of an acceptor impurity. It donates extra electrons to the semiconductor, creating an excess of negative charge carriers (electrons). N-type impurities are typically elements from Group V of the periodic table, such as phosphorus.

4. **D: Donor impurity**
   - A donor impurity is another term for an N-type impurity. It donates electrons to the semiconductor, increasing the number of free electrons available for conduction.

### Summary

- **Acceptor impurities** add holes, making the semiconductor P-type.
- **Donor impurities** add electrons, making the semiconductor N-type.

Understanding the role of acceptor and donor impurities is crucial for manipulating the electrical properties of semiconductors in electronic devices.