p11
Banned
In case of photodiode as reverse voltage increases , the width of depletion region increases , so sensitivity of the device increases . Now what is sensitivity ? I think that by this term they mean that when light falls on the device then , the electron hole pairs that are produced can fully contribute to current . Otherwise for narrow depletion layer , they may have a chance to recombine .so , if for a reverse bias voltage of 4v , the width of the depletion layer is x , then if 21 electrons are produced , out of which only 11 may contribute to current assuming that 10 are lost due to recombination . But if reverse bias voltage increases then , width of the depletion layer increases , so for the same light intensity if 21 electrons are produced , then i think more than 11 electrons can contribute current as less recombine .. so current should increase . But VI characterestics show that the photocurrent is almost independent of the reverse voltage .. plz explain ....