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When the light increases, the reverse current in a photo-diode______.
Increases
Decreases
Is unaffected
None
Increases
A photodiode operates in reverse bias mode, where the reverse saturation current is directly proportional to the intensity of incident light. When light strikes the depletion region, it creates electron-hole pairs, which are swept by the junction electric field, thereby increasing the reverse current.
A photodiode operates in reverse bias mode, where the reverse saturation current is directly proportional to the intensity of incident light. When light strikes the depletion region, it creates electron-hole pairs, which are swept by the junction electric field, thereby increasing the reverse current.
ItotalтАЛ=IsтАЛ+IphтАЛ тАФ where IsтАЛ is dark current and IphтАЛ is photocurrent
IphтАЛ=R├ЧP тАФ where R is responsivity and P is optical power
In the absence of light, only a small thermally generated leakage current (dark current) flows. When incident photons with energy EgтАЛ>h╬╜ enter the depletion region, they generate charge carriers (electron-hole pairs). The high reverse-bias potential accelerates these carriers across the junction, significantly increasing the current flow as intensity increases.
Photodiodes are operated in reverse bias because the depletion width is wider, leading to better photon absorption and faster response.
The dark current IsтАЛ is independent of light intensity and depends only on temperature.
The photocurrent IphтАЛ varies linearly with incident light intensity.
High sensitivity to incident light
Linear response over a wide range of light intensities
Presence of dark current limits the minimum detectable signal
Requires stable reverse bias power supply
Optical communication receivers
Light intensity measurement sensors
Remote control devices (IR receivers)
In forward bias, the photodiode acts like a standard diode and does not exhibit sensitivity to light changes effectively.
Option B is incorrect as the current increases, not decreases, with light.
Option C is incorrect because the junction depletion region is inherently light-sensitive.
A is correct тАФ The reverse current in a photodiode increases linearly with the intensity of incident light due to the generation of more electron-hole pairs.
Always remember that a photodiode acts as a current source that is controlled by light intensity when operated under reverse bias.