Hello Forum, trivial questions: physics phenomena are usually explained via simple models. In DC electronics the water analogy is often adopted but breaks down when we move to AC. When a simple diode is forward biased DC current is able to flow in the circuit powered by a constant voltage source. Holes meet the electrons and continue to recombine. Naively, I would wonder if at one point in time all the excess electrons available in the N doped part of the diode would meet up with the excess holes in the P-doped part and the process of electrical conduction would stop since there is no more movement of charge carriers. I know that physically that does not happen and the diode continues to work as a closed switch. What is wrong with the low level explanation of holes-electron recombination? Why does conduction not stop? Doping is the addition of a finite number of charge carriers. thanks!