Crystals of Silicon and Germanium are doped using two types of dopants:
1. The impurities for obtaining n-type semiconductor from intrinsic semiconductor are pentavalent impurity; like Arsenic (As), Antimony (Sb), Phosphorous (P), etc.
2. The impurities for obtaining p-type semiconductor from intrinsic semiconductor are trivalent impurity; like Indium (In), Boron (B), Aluminum (Al), etc.