metalloid

Metalloids, also called semimetals, are elements with properties that are intermediate between those of metals and nonmetals. They typically have a brittle, crystalline solid form, show metallic luster, and exhibit electrical conductivity that lies between that of metals and nonmetals. The conductivity of metalloids can be modified by temperature, impurities, or light, making them useful as semiconductors in electronic devices.

Commonly classified metalloids include boron, silicon, germanium, arsenic, antimony, and tellurium. They lie near the boundary between metals and nonmetals on the periodic table, often along or near the diagonal staircase that separates the two categories. Some classifications also count polonium, astatine, selenium, or other elements as metalloids depending on the criteria used.

Metalloids typically exhibit a mixture of metallic and nonmetallic chemical behaviors, with several showing amphoteric oxides and multiple common oxidation states. They tend to form covalent bonds and often form compounds with properties that are useful in industry, such as silicon dioxide in glass and silicon-based electronics. Their electrical properties are especially important, as they are widely used as semiconductors and in doped materials to control conductivity.

Applications include silicon as the primary material in most integrated circuits and solar cells; germanium as an early semiconductor material; boron used in glass and as a dopant; arsenic and antimony used as dopants in semiconductors; and tellurium used in several alloys and in certain photovoltaic materials.