Photodiode related enquiries

[torud]

i have some questions regarding photodiodes, made obvious by my title, so here it is:

- is it true that when a photodiode is in forward biased, it acts just like a normal diode? If so, then does it still receive photons from outside sources? if so, then does the photons received affected the forward- biased photodiode in any way?

-In a reverse biased photodiode, is there still a voltage drop in the diode itself? if so, why is there a voltage drop, since the dark current is generated by the photons itself?

-In a reverse-biased photodiode, what happens when no outside light source is shining on to the photodiode? does it act like a normal reverse-biased diode?

 

[jbsteele]

Yes, when a photodiode is in forward biased it acts just like a normal diode and can still receive photons from outside sources. The photons received can affect the forward-biased photodiode by generating a photocurrent, which can be used to detect the presence of light. In a reverse biased photodiode, there is a voltage drop due to the built-in potential of the diode. This is because the diode is designed to allow current to flow in only one direction. When no outside light source is shining on the photodiode, it acts like a normal reverse-biased diode and no current will flow.