What Are Diodes Made Out Of?

What Are Diodes Made Out Of?

• Silicon (Si) and Germanium (Ge) are the two most common single elements that are used to make Diodes.  A compound that is commonly used is Gallium Arsenide (GaAs), especially in the case of LEDs because of it’s large band gap.

The diagram above shows the 2D structure of the Si crystal.  The light green lines represent the electronic bonds made when the valence electrons are shared.  Each Si atom shares one electron with each of its four closest neighbors so that its valence band will have a full 8 electrons.

• Silicon and Germanium are both group 4 elements, meaning they have  4 valence electrons.  Their structure allows them to grow in a shape called the diamond lattice.
• Gallium is a group 3 element while Arsenide is a group 5 element.  When put together as a compound, GaAs creates a zincblend lattice structure.
• In both the diamond lattice and zincblend lattice, each atom shares its valence electrons with its four closest neighbors.  This sharing of electrons is what ultimately allows diodes to be build.  When dopants from groups 3 or 5 (in most cases) are added to Si, Ge or GaAs it changes the properties of the material so we are able to make the P- and N-type materials that become the diode.