
Semiconductor Components
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On the other hand, p-type silicon has a density of free holes (therefore “cti-
tious” free positive charges) equal to the density
N
of acceptors introduced by
doping. It can be said that
N
is normally much bigger than the
n
density of
free carriers naturally present in silicon at room temperature. In addition, it con-
tainsan equal number of xed negative ions. Therefore,
pN p
, but,
N
≫
p
, so
.
8.2.3 Law of Mass Action
When we dope, increasing the concentration of one type of carrier (n or p), the
consequence is that the other type of carrier will reduce in concentration (p orn).
In fact, the probabil ...