In summary the physics book describes it's operation as this:
- Gate = OFF = No potential difference applied to gate. This allows electrons to drift through the n channel (which is already there at the beginning). Current is maintained because of applied potential difference between source and drain.
- Gate = ON = Potential difference is applied to the gate, in such away that repels the electrons in the n channel into the p substrate. This reverse bias causes the depletion zone between the p-n junction to increase, causing the n-channel to decrease, and the current to stop due to a low amount of charge carriers.
mosfet that I'm used to (taken from a digital design book)
- Gate = OFF = No current due to no conduction path.
- Gate = ON = Electrons attracted to the gate, forming a n channel path for electrons to drift through, so current flows.