MOSFETs use this to their advantage. The "Body" of the MOSFET is powered negatively, which widens the depletion region, since the holes are filled with the new electrons, so the opposite force to the electrons on the N side becomes much larger. The "Source" of the MOSFET is powered negatively, which shrinks the depletion zone in the N type entirely, since there are enough electrons to fulfill the positive depletion zone. The "Drain" has a positive power. When the "Gate" is supplied with positive power, it will make a small electromagnetic field, which will remove the depletion zone directly below the gate, since there will be a "spray" of holes, which will make something called an "N-Channel". The N-Channel is a temporary region of the P-Type silicon area where there is no depletion zone. The positive electric field will neutralize all of the spare electrons that make up the depletion zone. The electrons in the source area will then have a clear way to move to the "Drain", which would make electricity flow from source to drain.