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Avalanche diodes (commonly encountered as high voltage Zener diodes) are constructed to break down at a uniform voltage and to avoid current crowding during breakdown. These diodes can indefinitely sustain a moderate level of current during breakdown. The voltage at which the breakdown occurs is called the breakdown voltage.
The Zener effect is distinct from avalanche breakdown. Avalanche breakdown involves minority carrier electrons in the transition region being accelerated, by the electric field, to energies sufficient for freeing electron-hole pairs via collisions with bound electrons. The Zener and the avalanche effect may occur simultaneously or independently ...
In an avalanche, one carrier collides with other atoms and knocks free new carriers. The result is that for each carrier that starts across a barrier, several carriers synchronously arrive. The result is a wide-bandwidth high-power source. Conventional diodes can be used in breakdown. The avalanche breakdown also has multistate noise.
A subsurface Zener diode, also called a buried Zener, is a device similar to the surface Zener, but the doping and design is such that the avalanche region is located deeper in the structure, typically several micrometers below the oxide. Hot carriers then lose energy by collisions with the semiconductor lattice before reaching the oxide layer ...
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 ...
Avalanche breakdown can also exhibit multi-state noise. The generated output noise appears to switch between two or more distinct levels. This noise has a 1/f characteristic. The effect can be minimized. Motchenbacher & Fitchen (1973, pp. 291–292) describe a noise source using a Zener diode (also suitable for an avalanche diode).
Download as PDF; Printable version; ... Avalanche breakdown; B. Breakdown voltage; Brush discharge; C. ... Zener effect This page was last ...
A plasma begins with a rare natural 'background' ionization event of a neutral air molecule, perhaps as the result of photoexcitation or background radiation.If this event occurs within an area that has a high potential gradient, the positively charged ion will be strongly attracted toward, or repelled away from, an electrode depending on its polarity, whereas the electron will be accelerated ...