Explain n-type and p-type semiconductors.

n - Type semiconductor: If small amount of pentavalent impurity (group V elements) is added to a pure semiconductor giving a large number of free electrons in this, the extrinsic semiconductor hence formed is called n- type semiconductor. This addition of pentavalent impurities as like arsenic and antimony offer a large number of free electrons in the semiconductor crystal. These type impurities, which create n- type semiconductors, are called donor impurities as each atom of them donates one free electron to conduction band in the semiconductor crystal.

p - Type semiconductor: If small amount of trivalent impurity group III elements is added to a pure semiconductor giving a huge number of holes in this, the extrinsic semiconductor thus formed is called p- type semiconductor. This addition of trivalent impurities as like gallium and indium give a large number of holes in the semiconductor crystal. These type impurities, that produce p- type semiconductors, are called acceptor impurities as each atom of them creates one hole, into valence band, that can accept one electron.