Avalanche diode

Avalanche diodes are optimized for avalanche effect, so they exhibit small but significant voltage drop under breakdown conditions, unlike Zener diodes that always maintain a voltage higher than breakdown.

[dubious – discuss] This feature provides better surge protection than a simple Zener diode and acts more like a gas-discharge tube replacement.

[2][dubious – discuss] The voltage after breakdown varies only slightly with changing current.

A common application is to protect electronic circuits against damaging high voltages.

They are commonly used as noise sources in radio equipment and hardware random number generators.

These are made from doped silicon and depend on the avalanche breakdown effect to detect even single photons.

In this regime, electron–hole pairs generated by the incident photons take a large amount of energy from the electric field, which creates more secondary charge carriers.