Element used to make semi-conductures

Answer 1

The most commonly used semiconductor element now is Silicon, sometimes Germanium is used. Selenium used to be used as a semiconductor in power rectifiers, its only remaining use as a semiconductor is the photosensitive coating on photocopier and laser printer drums. There is much hope that carbon (either in the form of vapor deposited diamond film or nanotubes) can be used as a semiconductor.

For special applications bi-elemental semiconductors are in use: boron-nitride, aluminum-phosphide, gallium-arsenide, indium-antimonide. Other combinations of these are possible too (e.g. indium-phosphide, boron-arsenide) depending on the exact properties wanted. These tend to be most common in very high speed devices (gallium-arsenide) or in various colored LEDs (e.g. aluminum-indium-phosphide).

Many other semiconductors exist composed of various compounds: Galena (Lead Sulfide), the organic compounds used in making OLEDs (Organic Light Emitting Diodes), Copper Oxide, etc.