I'm doing a course in solid state electronics and we just started PN junctions etc. I'm a bit confused.
So here is what I know so far:
Initially the P and N regions are separated by a a PN junction. At 300K as the acceptor atoms on the P side and donor atoms on the N side are ionised, there is a very high concentration of holes on the P side and electrons on the N side.
Diffusion occurs. Holes go to N side. Electrons go to P side. As the holes go to the N side they leave behind negatively charged acceptor atoms. And the electrons from the N side leave behind positvely charged donor atoms. So at this point there is a large concentration of negatively charged acceptor atoms near the junction and a large conc. of positvely charged donor atoms near the junction. This area is known as the depletion layer.
Now here is my question relating to this diagram:
In my notes it says that concentration of acceptor atoms in the neutral region of the P side(i.e excl the depletion layer) is Na. However that's clearly a contradiction because some of those Na acceptor atoms are now in the depletion layer. So shouldn't Na be the total number of acceptor atoms in the entire P region including the part of the depletion layer which is in the P side. Same for N side.