Lecture 3. Zener Region. As the reverse voltage increases the diode can avalanche-breakdown (zener breakdown). Zener breakdown occurs when the electric field near the junction becomes large enough to excite valence electrons directly into the conduction band and generate carriers.
Figure 1.33Determining the ac resistance at a Q-point.
For the characteristics of Fig. 1.34:
Figure 1.35 determining the average ac resistance between indicated limit