Which of the following materials would be best suited for use as a semiconductor?

• A. Silicon
• B. Copper
• C. Wood
• D. Glass

Answer: (A)

Semiconductors are materials whose ability to conduct electricity can be controlled, sitting between conductors and insulators. Silicon fits this role because its pure form has a moderate band gap, allowing a small number of charge carriers, and its conductivity can be precisely adjusted by adding impurities (doping) to create regions with surplus electrons or holes. This tunable behavior enables the formation of p–n junctions, which are essential for diodes, transistors, and many devices, plus silicon takes well to reliable oxide layers (SiO2) for insulation in complex circuits.

Copper is a metal with many free electrons, so its conductivity is high and not easily controlled. Wood and glass are insulators that resist current strongly and don’t provide the controllable conductivity required for semiconductor devices.