Solution:

• Process of adding impurity to a pure semiconductor is called doping.

• Depending on the type of impurities added, the semiconductor can be classified into p-type or n-type.

• When the p-n junction is formed a few electrons from the n-type diffuse through the junction and combines with the holes in the p-side to form negative ions and leaves behind positive ions in the n-side. This results in the formation of the depletion layer, which acts as the barrier and does not allow any further flow of electrons from the n region to the p region.

• As doping increases,width of depletion layer decreases.