At Intel Corporation, we want to hire those with at least a basic understanding of semiconductors. Why are some semiconductors made of silicon?
The interviewer is testing your basic industry knowledge. The better you understand a topic, the more clearly you should be able to answer a question like this. Keep your answer concise. 'I don't know' is never an acceptable answer. Be transparent with the interviewer that you are unsure of the solution but offer any piece of knowledge that you may have.
"From my understanding, some semiconductors are made of silicon because silicon can be altered to match the exact amount of energy that is needed to pass through a circuit. Silicon can handle high temperatures, which helps keep electronics stable and conserve energy. Additionally, silicon is used because it is more widely available and cheaper than other semiconductor sources."
"I am not confident on why some semiconductors are made of silicon; however, I believe that silicon is good for higher heat, so perhaps that is why. I would love to learn more if you would give me the opportunity."
Remember to include your knowledge of why silicon makes sense to use from a business perspective in addition to its practicality in engineering. For example, you might point out that the Earth has large silicon deposits, and it is fairly cheap to harvest compared to other semiconductors.