ELECTRONIC PRINCIPLES - OD1647 - LESSON 1/TASK 2
The holes in the collector are filled by electrons that flow
from the negative terminal of the battery, other electrons in
the base break their covalent bonds and enter the positive
terminal of the battery. Although there is only minority
current flow in tile reversebiased junction, it is still very
small due to the limited number of minority current carriers.
FIGURE 94. REVERSEDBIASED JUNCTION IN A PNP TRANSISTOR.
(3) PNP Junction Interaction. The interaction between the
forward and reversebiased junctions in a PNP transistor is
very similar to that in an NPN transistor, except that in the
PNP transistor, the majority current. carriers are holes. In
the PNP transistor shown in figure 95 on the following page, the
positive voltage on the emitter repeats the holes toward the
base. Once in the base, the holes combine with the base
electrons. However, the base region is made very thin to
prevent the recombination of holes with electrons. Therefore,
well over 90 percent of the holes that enter the base become
attracted to the large negative collector voltage rand pass
right through the base. However, for each electron and hole
that combine in the base region, another electron leaves the
negative terminal of the base battery (VBB} and
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