Q.Distinguish between avalanche and zener breakdown.

If the reverse bias on a p-n junction is increased enough, the junction 'breaks down' and reverse current rises sharply, via one of two distinct mechanisms depending on doping level. ZENER breakdown occurs in HEAVILY doped junctions with very narrow depletion layers ($<10^{-6}$ m): even a modest reverse voltage creates an extremely strong field (order $3\times10^7\ \text{V m}^{-1}$) strong enough to directly rupture covalent bonds in the lattice, generating electron-hole pairs (also called internal field emission). AVALANCHE breakdown occurs in LIGHTLY doped junctions with wide depletion layers, where the field alone is too weak to rupture bonds directly; instead, thermally generated minority carriers are accelerated by the field, collide with lattice atoms, and break bonds on impact, and the newly freed carriers a …