SOLUTION

• The majority carriers in a p-type semiconductor are holes acquired by the doping process. and the minority carrier is free electrons produced by the thermally generated electron-hole pair.
• These electron-hole pairs are thermally produced because the electron has acquired enough energy from external heat to break away from its atom.
• A free electron will eventually lose energy and fall back into a hole. This is called recombination. Electron-hole pairs are continuously being thermally generated so there are always free electrons in the material.
• The minority carriers are thermally produced and they exist only for a short time after which they recombine and neutralize each other.
• In the meantime, other minority carriers have been produced and this process goes on and on. The number of these electron-hole pairs that exist at any one time depends upon the temperature.
• The number of majority carriers is, however, fixed depending on the number of impurity atoms available.
• But it is to be noted that the minority carrier concentration in the doped semiconductors is smaller than that of intrinsic one because the presence of excess majority carriers in extrinsic semiconductors ‘kills’ some of the minority carriers by recombination process.