level Conduction band Valence band Si + Si + Si + Si + Si + Si + Hole Si + Si + + (a) Conduction band Valence band (b) Acceptor energy levels Figure . p -type extrinsic semiconductor (a) Hole generated by the dopant (b) Representation of acceptor energy level - - - - - - - - Unit electronics and Communication there is no net electric current across the junction. Thus, a p-n junction is formed. ii) Junction potential or barrier potential The movement of charge carriers across the junction takes place only to a certain point beyond which the depletion layer acts like a barrier to further diffusion of free charges across the junction.
This is due to the fact that the immobile ions on both sides establish an electric potential difference across the junction.