Novel phenomenon of avalanche breakdown saturation with negative resistance in a bipolar transistor

A breakdown saturation phenomenon of negative resistance has been observed in a bipolar transistor. The collector current becomes saturated and reaches a critical current (I_CC) after avalanche breakdown. At this critical current, a negative resistance appears. I_CC is determined by the thermal condition of the transistor, as obtained from pulse measurements and temperature dependence. For the multiplication factor (M), it is clear that there are two distinct regions: 1) low voltage (Region I) and 2) higher voltage (Region II). In Region I, the multiplication factor begins to increase with increasing applied voltage and is fixed almost constant for temperature, whereas in Region II, the multiplication factor decreases with increasing temperature. As a result, (∂M/∂V) _T≃0 is realized at about 20 V and 124°C, corresponding to the saturation of avalanche breakdown