The filled circles ( ) represent electrons
and empty circles ( ) represent holes Rationalised 2023-24
Physics
330
(ii) Trivalent (valency 3); like Indium (In),
Boron (B), Aluminium (Al), etc We shall now discuss how the doping
changes the number of charge carriers (and
hence the conductivity) of semiconductors Si or Ge belongs to the fourth group in the
Periodic table and, therefore, we choose the
dopant element from nearby fifth or third
group, expecting and taking care that the
size of the dopant atom is nearly the same as
that of Si or Ge