Page 954 - Basic Electrical Engineering

Figure 14.4 P-type semiconductor material

One position is left vacant which we call a hole. Similar to n-type material,
p-type material is also electrically neutral. The total number of electrons in
the orbits is equal to the total number of protons in the nucleus of the atoms.

Although the amount of impurity material added is small, the total number of
atoms being large produce a large number of holes in the crystal. Thus a p-

type material will have plenty of holes and an n-type material will have
plenty of free electrons. Electrons and holes constitute charge carriers. In a p-
type material the holes are the majority charge carriers. When temperature is

raised there will be creation of free electrons and holes. These thermally
generated electrons will be the minority charge carriers because of their being

small in numbers.

14.4.3 The p–n Junction

A p-type semiconductor can be represented by holes as the majority charge

carriers. The trivalent impurities that produce a p-type semiconductor are
called acceptor impurities because the holes are ready to accept any free

electrons. A free electron coming from elsewhere occupying a hole in a p-