Define intrinsic and extrinsic semiconductor.

    A semiconductor, which is in its extremely pure form, is known as an intrinsic (or pure) semiconductor. The nature of semiconductor is such that even a small amount of certain impurities can change their electrical properties drastically. It is due to this fact, that a semiconductor would not be called truly intrinsic, unless the impurity level is very low.

    When a small quantity of impurity is mixed in a pure or intrinsic semiconductor, the conductivity of semiconductor increases. Such an impure semiconductor is called the extrinsic semiconductor. The conductivity of resultant crystal  depends on the nature and quantity of the impurity added.Depending upon the nature of impurity added in intrinsic semiconductor.

The extrinsic semiconductor are two types-

   (i) N- type or donor

   (ii) P-type or acceptor.