Semiconductor Materials | @IEEEorg
What are the most used semiconductor materials?
The most used semiconductor materials are silicon, germanium, and gallium arsenide. Of the three, germanium was one of the earliest semiconductor materials used. Germanium has four valence electrons, which are electrons located on the outer shell of the atom.
The number of valence electrons in a semiconductor material determines its conductivity. While an important step in the evolution of semiconductor materials, germanium has largely fallen into disuse in favor of the current king of semiconductor materials—silicon.
Silicon has seen extensive use as a semiconductor material since the 1950s. The most abundant element on earth after carbon, silicon has four valence electrons and melts at a higher temperature than germanium (1,414 degrees Celsius in comparison to germanium’s 938.3 degrees Celsius).
Silicon is abundantly available in quartzite. Extraction, purification, and crystallization processes for silicon are both efficient and economical. The element crystallizes in a diamond form for a relatively robust bond, giving silicon crystals strong mechanical properties.
Gallium arsenide is the second most common semiconductor in use today. Unlike silicon and germanium, gallium arsenide is a compound, not an element, and is made by combining gallium, with its three valence electrons, with arsenic, which has five valence electrons.
Eight valence electrons make gallium-arsenide devices respond quickly to electric signals, making the compound well suited for amplifying the high-frequency signals seen in television satellites. Gallium arsenide has some limitations, however: the compound is more difficult to manufacture en masse than silicon, and the chemicals used in gallium arsenide production are quite toxic.
What are the most effective semiconductor materials?
In addition to gallium arsenide, the compound silicon dioxide has characteristics superior to silicon, allowing it to be used as an insulator, passivation layer, and a building layer in metal-oxide silicon (MOS) devices, a type of insulated-gate field-effect transistor. Silicon dioxide has a high dielectric strength and wider band gap than silicon, making it an effective insulator, and the compound is easily deposited on other materials.