Avalanche Photodiodes

Avalanche Photodiodes

These avalanche photodiodes (APDs) are silicon photodiodes with an internal gain mechanism. As with a conventional photodiode, absorption of incident photons creates electron-hole pairs. A high reverse bias voltage creates a strong internal electric field, which accelerates the electrons through the silicon crystal lattice and produces secondary electrons by impact ionization. The resulting electron avalanche can produce gain factors up to several hundred.

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