PN junctions and diodes
Which correctly describes the mechanism of avalanche breakdown?
- ACarriers accelerated by a high field collide with the lattice and create new electron-hole pairs, which multiply in a chain reaction
- BElectrons tunnel quantum-mechanically through a thin barrier
- CThe junction melts as the temperature rises
Show answer and explanation
Answer: A. Carriers accelerated by a high field collide with the lattice and create new electron-hole pairs, which multiply in a chain reaction
In avalanche breakdown, carriers accelerated by the strong field in the depletion layer collide with atoms and create electron-hole pairs (impact ionization); these are accelerated in turn and collide again, so the current grows like an avalanche. It tends to occur in junctions with relatively low doping and wide depletion layers.