I've been reading various explanations for a number of hours, and I'm still completely confused. I'll refer to an explanation from Wikipedia, but do point me to a better one if you know one. What does the depletion zone have to do with current flow? Looking at Figure A (see link above), there are plenty of charge carriers throughout the depletion layer, mostly holes on the left and mostly electrons on the right. And they are in equilibrium, so there is no net force stopping them. If a potential difference is applied either way, why won't current flow through the depletion zone like in a normal conductor, with the oncoming electrons filling the oncoming holes? In case it helps with pinpointing my source of confusion, I have (or should have) roughly high-school-level physics and chemistry knowledge (no such claims about understanding), I visualise free electrons as tiny charged balls that obey Newtonian physics and Coulomb's law and nothing more, and I don't understand how non-ionic chemical bonds work.