What is Band Gap Theory? - Electronics

What is Band Gap Theory?

The Band Gap Theory gives us a useful way to visualize the difference between conductors, insulators and semiconductors.

-A plot is made between the available energy levels for electrons in the materials. The available energy states form discrete energy levels instead of a continuous spectra.

-Crucial to the conduction process is whether or not there are electrons in the conduction band.

-In insulators the electrons in the valence band are separated by a large gap from the conduction band.

-In conductors like metals the valence band overlaps the conduction band.

-In semiconductors there is a small enough gap between the valence and conduction bands that thermal or other excitations can bridge the gap.

-An important parameter is the Fermi level energy. The position of the Fermi level with the relation to the conduction band is a crucial factor in determining electrical properties.