ELECTRONIC PRINCIPLES - OD1647 - LESSON 1/TASK 2
generated by this current converts the material nearest the
point of contact to a Ptype material as shown in figure 78,
view B.
j. PN Junction Operation. P and Ntype materials, how these
materials are joined together to form a diode, and the function
of the diode, have now been introduced. But before we can
understand how the PN junction works, we must first consider
current flow in the materials that make up the junction and then
what happens initially within the junction when these two
materials are joined together.
FIGURE 78. POINTCONTACT TYPE OF DIODE CONSTRUCTION.
(1) Current Flow in the NType Material. Current flow in an
Ntype material is similar to conduction in a copper wire. That
is, with voltage applied across the material, electrons will
move through the crystal toward the positive terminal just as
current flows in a copper wire (figure 79 on the following page).
(2) Current Flow in the PType Material. Current flow in a P
type material is by positive holes, instead of negative
electrons. Unlike the electron, the hole moves from the
positive terminal of the P material to the negative terminal
(figure 80 on the following page).
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