Figure 2-51C.Point-contact diode. CUT AWAY VIEW.
Figure 2-51D.Point-contact diode. SCHEMATIC SYMBOL.
The pointed wire is used instead of a flat metal plate to produce a high-intensity electric field at the
point contact without using a large external source voltage. It is not possible to apply large voltages across
the average semiconductor because of the excessive heating.
The end of the catwhisker is one of the terminals of the diode. It has a low-resistance contact to the
external circuit. A flat metal plate on which the crystal is mounted forms the lower contact of the diode
with the external circuit. Both contacts with the external circuit are low-resistance contacts.
The characteristics of the point-contact diode under forward and reverse bias are somewhat different
from those of the junction diode.