What it meansEdit
It is a form of electric current multiplication that can allow very large currents to flow within materials which are otherwise good insulators.
Avalanche breakdown can occur within insulating or semiconducting solids, liquids, or gases when the electric field in the material is great enough to accelerate free electrons to the point that, when they strike atoms in the material, they can knock other electrons free. This phenomenon is usefully employed in special purpose semiconductor devices such as the avalanche diode, the avalanche photodiode and the avalanche transistor, as well as in some gas filled tubes.
When an avalanche-like effect occurs without connecting two electrodes, it is referred to as an electron avalanche. Although there are some superficial similarities to Zener breakdown, the physical origins of the two phenomena are very different.
If the current is not externally limited, the process normally destroys the device where it has started, and in situations such as power line insulators, this can take the form of an explosive breakdown of the insulator. In avalanche diodes, this effect is mainly used to construct over voltage protection circuits and voltage reference circuits.
As a matter of fact, avalanche breakdown and Zener breakdown are jointly present in each avalanche diode, depending on breakdown voltage, which is the leading contributing process to the avalanche current.
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