Very basic questions about photodiode

[gusts]

Hello all,

I know the basic terms regarding a photodiode - quantum efficiency, photosensitivity, short-circuit current etc. But I don't understand several things about photosensitivity and photocurrent.
1) Is photosensitivity (A/W) almost the same for all Si photodiodes?
2) If photosensitivity of two photodiodes is the same why does photocurrent differ so much (microamps for one diode, but even 500 mA for another)?
3) What does the photocurrent depends on?
4) Why is it so that two photodiodes with the same active area and equal photosensitivity have so different photocurrents?
5) Is short-circuit current the same photocurrent measured under specific conditions?

Thanks and best regards and sorry for the questions
gusts

 

[FvM]

1) Is photosensitivity (A/W) almost the same for all Si photodiodes?

The answer is related to qunatum effiency. Regular photodiodes don't involve charge carrier multiplication and thus have < 1 Q.E. by nature. Most photo diodes have a quantum efficiency in a 0.3 to 0.9 range which results in a typical A/W versus λ characteristic. In so far most photo diodes have the same A/W order of of magnitude. I presume you understand that A/W depends on λ by working of Planck's law. See e.g. **broken link removed**

Regarding other questions, I don't understand what you are comparing. Obviously the irradiation and diode area must be the same when comparing photo diode sensitivity. Maximum diode current would be a different parameter that's no directly related to sensitivity.