What is dopent.  How does dopent …

Dopant: A substance used to produce a desired electrical characteristic in a semiconductor.

Dopant increses the conductivity of semiconductor by creating new donor level near to conduction band or acceptor level near to valence band.

Doping is nothing but adding N or P type impurities to a pure semiconductor. So these impurities will contain electrons or holes based on their impurity. When these kind of doping takes place in semiconductors and voltage is applied, these electrons will conduct electricity. In case of holes, electrons due to potential excitation jump from their original positions to these holes and form immobile ions at that point, whereas equal amount of holes are created from where these electrons jumped. Thus conductivity increases due to doping.