Question

Please explain whether ,the donor 'ions' and acceptor 'ions' ,in a PN junction diode are formed after the flow of electrons from n side to p side during the formation of depletion layer or do they exist even before the flow of electrons ?

Answer 1

The donor and acceptor atoms/ions are what causes the deplete region to form. Without the doping there would be no electron/hole current flowing in the semiconductor. The semiconductor, lets say its silicon, sits there by itself and will not be useful until it is doped with the donor/acceptor atoms, which causes the depletion region to form