What are solid-state devices that fall between conductors and insulators called?

Solid-state devices that fall between conductors and insulators are called semiconductors. Semiconductors possess unique electrical properties that allow them to conduct electricity under certain conditions, typically when subjected to specific temperatures, voltages, or doping with impurities. This property enables them to be very useful in various electronic applications, including transistors, diodes, and integrated circuits, which are essential components in modern electronics.

In contrast, conductors allow the free flow of electrons, providing low resistance to electrical current, while insulators block the flow of electricity entirely and exhibit high resistance. Superconductors are materials that can conduct electricity without resistance under particular conditions, but they do not fit the intermediate classification between conductors and insulators. Therefore, semiconductors are correctly identified as the category that occupies this critical range in electrical conductivity.