semiconductor devices

Asked by deepak.embedded | 28th Apr, 2010, 05:32: PM

Expert Answer:

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.

Answered by  | 29th Apr, 2010, 02:46: PM

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