Energy Band Diagram

Energy band diagram in qualitative form is sketched by following the following process:

1. The semiconductor device is supposed to be made by bringing together the several distinct semiconductor layers, metals or insulators of that it is composed. The starting point is hence the energy band diagram of all the constituent layers.

2. The  band  diagram  of  the  composite  device  is  sketched  by using  the  fact  that after equilibrium, the Fermi energy is similar everywhere in the system. The equalization of the Fermi energy is accompanied along with transfer of electrons from regions of higher Fermi energy to area of lower Fermi energy and viceversa for holes.

3. The redistribution of charges effects in electric field and creation of potential barriers in the system. These influences however are confined only close to the interface among the layers. The regions that are far from the interface remain as they were before the equilibrium.