What is meant by doping?
Doping: Semiconductors in its extremely pure form are termed as intrinsic semiconductor such intrinsic semiconductor to which several suitable impurities is added in extremely small amount are termed as extrinsic semiconductor. That process is termed as doping and impurities are as termed as doping agent. Generally the doping agents are pentavalent atom as arsenic, antimony or trivalent atom as indium, gallium and aluminium.