What are intrinsic and extrinsic semiconductors ?

The semiconductors are of mainly two types-

(i) intrinsic semiconductor - A semiconductor, which is in its extremely pure form , is known as an intrinsic (or pure) semiconductor. The nature of semiconductors 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 small .
The silicon and germanium are two most widely used intrinsic semiconductors.

(i) Extrinsic semiconductors- When a small quantity of impurity is mixed in a pure or intrinsic semiconductor is called the extrinsic semiconductors. 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 of two types-
    (a) N- type or doner
    (a) P- type or acceptor.