AVALANCHE

If a diode is reverse-biased and the voltage becomes high enough, the p-n junction will conduct. This is known as avalanche effect. The reverse current, which is near zero at lower voltages, rises dramatically. The avalanche voltage varies among different kinds of diodes. Figure 1 is a graph of the characteristic current-versus-voltage curve for a typical semiconductor diode showing the avalanche point. The avalanche voltage is considerably greater than and is of the opposite polarity from the forward breakover voltage. A Zener diode makes use of avalanche effect. Zener diodes are specially manufactured to have precise avalanche voltages. They form the basis for voltage regulation in dc power supplies

Fig. 1. Characteristic curve for a semiconductor diode..