...............is used to prepare semiconductor grade silicon or germanium.

Answer

**Step-by-Step Solution:**

1. **Identify the Process**: The question asks for a method used to prepare semiconductor-grade silicon or germanium. The correct process is known as "zone refining."

2. **Understanding Zone Refining**: Zone refining is a purification technique that is particularly effective for materials like silicon and germanium, which are used in semiconductor applications.

3. **Process Description**:
- **Heating**: The material (silicon or germanium) along with its impurities is subjected to strong heating. This causes the material to melt.
- **Cooling**: After melting, the material is cooled down. As it cools, the pure material begins to crystallize.
- **Separation of Impurities**: During the crystallization process, the impurities do not crystallize and remain in the molten state. This allows for the separation of the pure semiconductor material from the impurities.

4. **Outcome**: The end result of the zone refining process is the production of high-purity silicon or germanium, suitable for semiconductor applications.

5. **Final Answer**: Therefore, the answer to the question is "Zone refining."

---