Avalanche Breakdowm

In case of reverse biasing when the reverse bias voltage is made sufficient high,the electric field across the depletion region increased.

           V=Ed

The high electric field across the juction applies force on the minority charge carriers in the n-side and in the p-side.

When the energetic free electrons collide with the atoms of the crystal in the charge depletion region,then the covalent bond breaks and electron-hole pairs are produced.

These free electrons further help in creating more electron- hole pairs by participating in the collision process with the other atoms of the crystal creating large number of electron-hole pairs.

This process is known as avalanche breakdown