Why are photodiodes preferably operated under reverse bias when the current in the forward bias is known to be more than that in reverse bias?

Question

(a) Why are photodiodes preferably operated under reverse bias when the current in the forward bias is known to be more than that in reverse bias?

(b) The two optoelectronic devices: - Photodiode and solar cell, have the same working principle but differ in terms of their process of operation. Explain the difference between the two devices in terms of (i) biasing, (ii) junction area and (iii) I-V characteristics.

Answer 1

(a) The fractional change in majority charge carriers is very less compared to the fractional change in minority charge carriers on illumination.

(b) The difference in the working of two devices:

	Photodiode	Solar cell
Biasing	Used in Reverse biasing	No external biasing is given
Junction Area	Small	Large for solar radiation to be incident on it.
I-V characteristics