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 FIGURE 14 6 (a)  An intrinsic semiconductor at T = 0 K
behaves like insulator (b)  At T > 0 K, four thermally generated
electron-hole pairs