This two-terminal device generates a photocurrent when photons strike its active area, knocking electrons loose. It typically operates in reverse bias to increase the depletion region width, which lowers junction capacitance and improves response time. Engineers use them in fiber optic receivers, smoke detectors, and solar cells.
We need a faster photodiode for the receiver if we want to hit the gigabit spec.
The dark current specification tells you how much noise the diode produces when completely shielded from light.
Do not mix it up with
- Phototransistor: A photodiode only generates a small current from light, while a phototransistor amplifies that current internally.
Related terms
Phototransistor
A bipolar junction transistor that uses incident light instead of an electrical signal to control its base current.
Photoresistor
A passive component whose electrical resistance drops when exposed to light.
Diode
A two-terminal semiconductor component that restricts electrical current to flow in only one direction.