What is Avalanche Breakdown
Minority carriers, under reverse biased conditions, flowing through the junction acquires a kinetic energy that increases with increase in reverse voltage. At a sufficiently high reverse voltage (say 5v or more), kinetic energy of minority carriers becomes so large that they knock out electrons from the covalent bonds of semiconductor material. As a result of collision, liberated electrons in turn liberate more electrons and current becomes very large leading the breakdown of crystal structure itself. This phenomenon is known as Avalanche Breakdown.