If only its purpose is to create an additional electron-hole pair,then why would it be made reverse biased.We can good amount of current in forward biased condition.


The whole point of a photodiode is to detect light, and it does this by measuring the effect the light has on the current.

If we forward bias the photodiode then there is already a high current flowing and the extra current caused by the light is small and hard to measure. If we reverse bias the photodiode then (almost) no current is flowing and now the extra current caused by the light is very easily measureable.

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  • $\begingroup$ Adding a reverse bias also increases the thickness of the depletion layer, increasing the active volume where electron-hole generation will result in current out of the device. $\endgroup$ – Jon Custer Nov 19 '15 at 13:42

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