Question

The current in the forward bias is know to be more (~ mA) than the current in the reverse bias (~ $\mu$A). What the reason, then to operate the photodiode in reverse bias?

Answer 1

1. The photodiode is operated in reversed biased because in reversed bias the width of the depletion layer increases.

2. this reduces the junction capacitance and thereby by response time, this causes faster response times for the photodiode is reversed biased.

3. Even though the current in the forward bias is known to be more $(\sim mA)$ than the current in reverse bias $(\sim \mu A)$

4. Since, in forward bias, the width of depletion reduces, so only a small portion of the incident photons gets converted to electric current.