| Intrinsic semiconductor | Extrinsic semiconductor |
| (i). It is a pure semiconducting material and no impurity atoms are added to it. | (i). It is prepared by doping a small quantity of impurity atoms to the pure semiconducting material |
| (ii). Examples are crystalline forms of pure silicon and germanium. | (ii). Examples are silicon and germanium crystals with impurity atoms of arsenic, antimony, phosphorous etc. or indium, boron, aluminum etc |
| (iii). The no. of free electrons in conduction band and the number of holes in valence band is exactly equal and very small indeed. | (iii). The number of free electrons and holes are never equal. There is excess of electrons in n-type semiconductors and excess of holes in p-type semiconductors |
| (iv). Its electrical conductivity is low. | (iv). Its electrical conductivity is low. |
