Question

current in forward bias is known to be more than current in reverse bias why then does the photodiode operate under the reverse bias?

Answer 1

The incident light in photodiode converts to electric current “converts more effectively in reverse bias condition than in the forward bias condition”.

“In reverse biased “pn” junction”, the depletion regions width increases according to the “increase in the applied reverse bio voltage across the diode”.  Larger voltage converts more of incident photons into electric current.  In other words, the efficiency increases.

 

Answer 2

Answer:

at the junction, the new electrons and holes are generated but the hole move towards p type and elctron move towards n side.

Hence a reverse current is obtained which Is directly proportional to the intensity of incident light , due to it photo diode is used at reverse biasing.