Negative resistance characteristics of Zener diode at onset of avalanche breakdown

In a low current region (∼100μA) within a narrow voltage near the onset of primary breakdown, a negative resistance effect has been observed in a 4 kV high-voltage Zener diode. The region is much lower than ihe secondary breakdown region (∼ 100 mA) where negative resistance phenomena have previously been reported for Zener diodes. Measured I—V and oscillation characteristics of high-and low-voltage (<200 V) Zener diodes in the low current region are described, confirming the presence of negative resistance.