CBSE Class 12-science Answered

Dear student,

Zener breakdown is due to the high electric field present at the junction.Because of the high E , a sufficiently 
strong force exerted on a bound electron by the field to tear it out of its covalent bond . The new holeelectron pair
created increases the reverse current.(for highly doped diodes)
 
 Avalanche breakdown is due to collisions .   A thermally generated carrier falls down the junction barrier and 
acquires energy from the applied potential . This carrier collides with a crystal ion and imparts sufficient energy
to disrupt a covalent bond . In addition to original carrier a new electron-hole pair is generated . This cumulative

process is referred to as avalanche multiplication.

Team

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