The conclusion of the thinking below had been summarized in Appendix 3 and Appendix 2. Please read them carefully. The good news is that they are merely a summary of the lecture notes 15 and 16. However, they may be re-emphasizing clearly what to consider and what not to have to struggle with too much.

I have been thinking about the photo-voltaic effect a bit more.

I think N. had a point in saying that while the electron that gets sucked into the depletion region causes the current, obviously, the hole that gets left over by it also causes current! In fact, I think N. had it right and I was misleading in saying that the hole did not contribute to the current!

So, let us get this one straight.

The question is -- an electron and a hole get split on the p side, and the electron gets sucked into the depletion region and gets deposited into the n side. My new claim is that both of these actually cause the current. This makes much more sense!

Related to this is the fact, even the electron hole pairs that are temporarily created deep within the quasi-neutral region and die sometime later will give rise to the current before recombining! (That is what we call the normal photo-conductivity.)

Another thing – the magnitude of the electric field in the depletion region is not so important. I uploaded an appendix for this, just now.