The dopant has to be such that it does not distort the original pure
semiconductor lattice It occupies only a very few of the original
semiconductor atom sites in the crystal A necessary condition to attain
this is that the sizes of the dopant and the semiconductor atoms should
be nearly the same There are two types of dopants used in doping the tetravalent Si
or Ge:
(i)
Pentavalent (valency 5); like Arsenic (As), Antimony (Sb), Phosphorous
(P), etc