Photodiodes are PN junctions designed for detecting light and are used in cameras, intruder detectors, etc. Photodiodes are used to detect fast pulses of near-infrared light such as in a light meter. There are two oeprating modes of electronic photodiodes, photovoltaic and photoconductive. In the former, a small current flows when the diode is not illuminated (known as the ‘dark current’ and a higer current will flow when the photodiode is lit. In the latter, No current flows when it the photodiode is not lit, but current flows when it is illuminated. The diode is reverse-biased.
Types of photodiodes
Small Area photodiodes: These have fast response times when they are used in the reverse-biased photoconductive mode.
Large Area photodiodes: These have a slower response time, but are more sensitive due to their larger area.
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