Photodiode

Photodiode characteristic curve

Photodiodes are semi-Conductor components in which light waves can fall on a p-n junction and cause a change in current. A photodiode can be operated in three different ways:

• As a photovoltaic element: In the case of a voltage $V > 0$ at the Diode, the photodiode produces electrical energy on exposure to light and thus works like a Solar cell.
• In short-circuit mode: The diode produces a current in the reverse direction with linear dependence on the irradiance.
• In the off-state region: An off-state current flows with linear dependence on the light at a voltage $V < 0$. This mode of operation is used above all in integrated CMOS sensors.