semiconductor

A semiconductor is a material with electrical conductivity intermediate in magnitude between that of a conductor and an insulator. Semiconductor materials are the foundation of modern electronics, including radio, computers, telephones, and many other devices. Such devices include transistors, solar cells, many kinds of diodes including the light-emitting diode (LED), the silicon controlled rectifier, photo-diode, and digital and analog integrated circuits. Semiconductor solar photovoltaic panels directly convert light energy into electricity. In a metallic conductor, current is carried by the flow of electrons.

Common semiconducting materials are crystalline solids—chips, but amorphous and liquid semiconductors are also known. These include hydrogenated amorphous silicon and mixtures of arsenic, selenium and tellurium in a variety of proportions. Such compounds share with better known semiconductors intermediate conductivity and a rapid variation of conductivity with temperature, as well as occasional negative resistance.