2-4
Figure 2-3.—Transistor representations.
Another point you should keep in mind is that the arrow always points in the direction of hole flow, or
from the P to N sections, no matter whether the P section is the emitter or base. On the other hand, electron
flow is always toward or against the arrow, just like in the junction diode.
CONSTRUCTION
The very first transistors were known as point-contact transistors. Their construction is similar to the
construction of the point-contact diode covered in chapter 1. The difference, of course, is that the
point-contact transistor has two P or N regions formed instead of one. Each of the two regions constitutes an
electrode (element) of the transistor. One is named the emitter and the other is named the collector, as shown
in figure 2-4, view A.
