Physics - Semiconductors Question with Solution | TestHub

In photo–diode, the diode is connected in reverse bias, so initially the current will be very small. If the light is incident on the diode, its photons produce more minority charge carriers, which are called photo-generated charge carriers, due to which the reverse current increases.

In reverse bias, the width of the depletion region is more and the current is already very small, So the fractional charge in the current due to the light will be large.