selenium (Se)

Selenium (Se) is a chemical element that has atomic number 34 in the periodic table of elements. It has semiconductor properties and was used in rectifiers and bridge rectifiers in the last century.

Selenium was increasingly replaced by silicon( Si) as a semiconductor in the 1970s. The band gap between conduction band and valence band is 1.74 electron volts( eV).

Selenium is sensitive to light, as evidenced by the conductivity of electrons at different spectral frequencies. It is therefore used in combination with other semiconductor materials such as gallium( Ga) and indium( In) in photovoltaics, for example in photodiodes and photoresistors. Selenium exists in various modifications as black, gray and red selenium, of which gray selenium has the most stable properties.