A dopant, also called a doping agent, is a trace impurity element that is inserted into a substance (in very low concentrations) in order to alter the electrical properties or the opticalproperties of the substance. In the case of crystalline substances, the atoms of the dopant very commonly take the place of elements that were in the crystal lattice of the material. These materials are very commonly either crystals of a semiconductor (silicon, germanium, etc.), for use in solid-state electronics; or else transparent crystals that are used to make lasers of various types.
An intentional impurity such as Nitrogen or Boron added to the silicon carbide to engineer or alter the resistivity.which cause n-type dopant and p type dopant. As the dopant increases in concentration per cubic cm the resistivity is reduced.